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# sqlglot.optimizer.simplify

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       1from __future__ import annotations
       2
       3import datetime
       4import logging
       5import functools
       6import itertools
       7import typing as t
       8from collections import deque, defaultdict
       9from functools import reduce
      10
      11import sqlglot
      12from sqlglot import Dialect, exp
      13from sqlglot.helper import first, merge_ranges, while_changing
      14from sqlglot.optimizer.scope import find_all_in_scope, walk_in_scope
      15
      16if t.TYPE_CHECKING:
      17    from sqlglot.dialects.dialect import DialectType
      18
      19    DateTruncBinaryTransform = t.Callable[
      20        [exp.Expression, datetime.date, str, Dialect, exp.DataType], t.Optional[exp.Expression]
      21    ]
      22
      23logger = logging.getLogger("sqlglot")
      24
      25# Final means that an expression should not be simplified
      26FINAL = "final"
      27
      28# Value ranges for byte-sized signed/unsigned integers
      29TINYINT_MIN = -128
      30TINYINT_MAX = 127
      31UTINYINT_MIN = 0
      32UTINYINT_MAX = 255
      33
      34
      35class UnsupportedUnit(Exception):
      36    pass
      37
      38
      39def simplify(
      40    expression: exp.Expression,
      41    constant_propagation: bool = False,
      42    dialect: DialectType = None,
      43    max_depth: t.Optional[int] = None,
      44):
      45    """
      46    Rewrite sqlglot AST to simplify expressions.
      47
      48    Example:
      49        >>> import sqlglot
      50        >>> expression = sqlglot.parse_one("TRUE AND TRUE")
      51        >>> simplify(expression).sql()
      52        'TRUE'
      53
      54    Args:
      55        expression: expression to simplify
      56        constant_propagation: whether the constant propagation rule should be used
      57        max_depth: Chains of Connectors (AND, OR, etc) exceeding `max_depth` will be skipped
      58    Returns:
      59        sqlglot.Expression: simplified expression
      60    """
      61
      62    dialect = Dialect.get_or_raise(dialect)
      63
      64    def _simplify(expression, root=True):
      65        if (
      66            max_depth
      67            and isinstance(expression, exp.Connector)
      68            and not isinstance(expression.parent, exp.Connector)
      69        ):
      70            depth = connector_depth(expression)
      71            if depth > max_depth:
      72                logger.info(
      73                    f"Skipping simplification because connector depth {depth} exceeds max {max_depth}"
      74                )
      75                return expression
      76
      77        if expression.meta.get(FINAL):
      78            return expression
      79
      80        # group by expressions cannot be simplified, for example
      81        # select x + 1 + 1 FROM y GROUP BY x + 1 + 1
      82        # the projection must exactly match the group by key
      83        group = expression.args.get("group")
      84
      85        if group and hasattr(expression, "selects"):
      86            groups = set(group.expressions)
      87            group.meta[FINAL] = True
      88
      89            for e in expression.selects:
      90                for node in e.walk():
      91                    if node in groups:
      92                        e.meta[FINAL] = True
      93                        break
      94
      95            having = expression.args.get("having")
      96            if having:
      97                for node in having.walk():
      98                    if node in groups:
      99                        having.meta[FINAL] = True
     100                        break
     101
     102        # Pre-order transformations
     103        node = expression
     104        node = rewrite_between(node)
     105        node = uniq_sort(node, root)
     106        node = absorb_and_eliminate(node, root)
     107        node = simplify_concat(node)
     108        node = simplify_conditionals(node)
     109
     110        if constant_propagation:
     111            node = propagate_constants(node, root)
     112
     113        exp.replace_children(node, lambda e: _simplify(e, False))
     114
     115        # Post-order transformations
     116        node = simplify_not(node)
     117        node = flatten(node)
     118        node = simplify_connectors(node, root)
     119        node = remove_complements(node, root)
     120        node = simplify_coalesce(node)
     121        node.parent = expression.parent
     122        node = simplify_literals(node, root)
     123        node = simplify_equality(node)
     124        node = simplify_parens(node)
     125        node = simplify_datetrunc(node, dialect)
     126        node = sort_comparison(node)
     127        node = simplify_startswith(node)
     128
     129        if root:
     130            expression.replace(node)
     131        return node
     132
     133    expression = while_changing(expression, _simplify)
     134    remove_where_true(expression)
     135    return expression
     136
     137
     138def connector_depth(expression: exp.Expression) -> int:
     139    """
     140    Determine the maximum depth of a tree of Connectors.
     141
     142    For example:
     143        >>> from sqlglot import parse_one
     144        >>> connector_depth(parse_one("a AND b AND c AND d"))
     145        3
     146    """
     147    stack = deque([(expression, 0)])
     148    max_depth = 0
     149
     150    while stack:
     151        expression, depth = stack.pop()
     152
     153        if not isinstance(expression, exp.Connector):
     154            continue
     155
     156        depth += 1
     157        max_depth = max(depth, max_depth)
     158
     159        stack.append((expression.left, depth))
     160        stack.append((expression.right, depth))
     161
     162    return max_depth
     163
     164
     165def catch(*exceptions):
     166    """Decorator that ignores a simplification function if any of `exceptions` are raised"""
     167
     168    def decorator(func):
     169        def wrapped(expression, *args, **kwargs):
     170            try:
     171                return func(expression, *args, **kwargs)
     172            except exceptions:
     173                return expression
     174
     175        return wrapped
     176
     177    return decorator
     178
     179
     180def rewrite_between(expression: exp.Expression) -> exp.Expression:
     181    """Rewrite x between y and z to x >= y AND x <= z.
     182
     183    This is done because comparison simplification is only done on lt/lte/gt/gte.
     184    """
     185    if isinstance(expression, exp.Between):
     186        negate = isinstance(expression.parent, exp.Not)
     187
     188        expression = exp.and_(
     189            exp.GTE(this=expression.this.copy(), expression=expression.args["low"]),
     190            exp.LTE(this=expression.this.copy(), expression=expression.args["high"]),
     191            copy=False,
     192        )
     193
     194        if negate:
     195            expression = exp.paren(expression, copy=False)
     196
     197    return expression
     198
     199
     200COMPLEMENT_COMPARISONS = {
     201    exp.LT: exp.GTE,
     202    exp.GT: exp.LTE,
     203    exp.LTE: exp.GT,
     204    exp.GTE: exp.LT,
     205    exp.EQ: exp.NEQ,
     206    exp.NEQ: exp.EQ,
     207}
     208
     209
     210def simplify_not(expression):
     211    """
     212    Demorgan's Law
     213    NOT (x OR y) -> NOT x AND NOT y
     214    NOT (x AND y) -> NOT x OR NOT y
     215    """
     216    if isinstance(expression, exp.Not):
     217        this = expression.this
     218        if is_null(this):
     219            return exp.null()
     220        if this.__class__ in COMPLEMENT_COMPARISONS:
     221            return COMPLEMENT_COMPARISONS[this.__class__](
     222                this=this.this, expression=this.expression
     223            )
     224        if isinstance(this, exp.Paren):
     225            condition = this.unnest()
     226            if isinstance(condition, exp.And):
     227                return exp.paren(
     228                    exp.or_(
     229                        exp.not_(condition.left, copy=False),
     230                        exp.not_(condition.right, copy=False),
     231                        copy=False,
     232                    )
     233                )
     234            if isinstance(condition, exp.Or):
     235                return exp.paren(
     236                    exp.and_(
     237                        exp.not_(condition.left, copy=False),
     238                        exp.not_(condition.right, copy=False),
     239                        copy=False,
     240                    )
     241                )
     242            if is_null(condition):
     243                return exp.null()
     244        if always_true(this):
     245            return exp.false()
     246        if is_false(this):
     247            return exp.true()
     248        if isinstance(this, exp.Not):
     249            # double negation
     250            # NOT NOT x -> x
     251            return this.this
     252    return expression
     253
     254
     255def flatten(expression):
     256    """
     257    A AND (B AND C) -> A AND B AND C
     258    A OR (B OR C) -> A OR B OR C
     259    """
     260    if isinstance(expression, exp.Connector):
     261        for node in expression.args.values():
     262            child = node.unnest()
     263            if isinstance(child, expression.__class__):
     264                node.replace(child)
     265    return expression
     266
     267
     268def simplify_connectors(expression, root=True):
     269    def _simplify_connectors(expression, left, right):
     270        if left == right:
     271            if isinstance(expression, exp.Xor):
     272                return exp.false()
     273            return left
     274        if isinstance(expression, exp.And):
     275            if is_false(left) or is_false(right):
     276                return exp.false()
     277            if is_null(left) or is_null(right):
     278                return exp.null()
     279            if always_true(left) and always_true(right):
     280                return exp.true()
     281            if always_true(left):
     282                return right
     283            if always_true(right):
     284                return left
     285            return _simplify_comparison(expression, left, right)
     286        elif isinstance(expression, exp.Or):
     287            if always_true(left) or always_true(right):
     288                return exp.true()
     289            if is_false(left) and is_false(right):
     290                return exp.false()
     291            if (
     292                (is_null(left) and is_null(right))
     293                or (is_null(left) and is_false(right))
     294                or (is_false(left) and is_null(right))
     295            ):
     296                return exp.null()
     297            if is_false(left):
     298                return right
     299            if is_false(right):
     300                return left
     301            return _simplify_comparison(expression, left, right, or_=True)
     302
     303    if isinstance(expression, exp.Connector):
     304        return _flat_simplify(expression, _simplify_connectors, root)
     305    return expression
     306
     307
     308LT_LTE = (exp.LT, exp.LTE)
     309GT_GTE = (exp.GT, exp.GTE)
     310
     311COMPARISONS = (
     312    *LT_LTE,
     313    *GT_GTE,
     314    exp.EQ,
     315    exp.NEQ,
     316    exp.Is,
     317)
     318
     319INVERSE_COMPARISONS: t.Dict[t.Type[exp.Expression], t.Type[exp.Expression]] = {
     320    exp.LT: exp.GT,
     321    exp.GT: exp.LT,
     322    exp.LTE: exp.GTE,
     323    exp.GTE: exp.LTE,
     324}
     325
     326NONDETERMINISTIC = (exp.Rand, exp.Randn)
     327AND_OR = (exp.And, exp.Or)
     328
     329
     330def _simplify_comparison(expression, left, right, or_=False):
     331    if isinstance(left, COMPARISONS) and isinstance(right, COMPARISONS):
     332        ll, lr = left.args.values()
     333        rl, rr = right.args.values()
     334
     335        largs = {ll, lr}
     336        rargs = {rl, rr}
     337
     338        matching = largs & rargs
     339        columns = {m for m in matching if not _is_constant(m) and not m.find(*NONDETERMINISTIC)}
     340
     341        if matching and columns:
     342            try:
     343                l = first(largs - columns)
     344                r = first(rargs - columns)
     345            except StopIteration:
     346                return expression
     347
     348            if l.is_number and r.is_number:
     349                l = l.to_py()
     350                r = r.to_py()
     351            elif l.is_string and r.is_string:
     352                l = l.name
     353                r = r.name
     354            else:
     355                l = extract_date(l)
     356                if not l:
     357                    return None
     358                r = extract_date(r)
     359                if not r:
     360                    return None
     361                # python won't compare date and datetime, but many engines will upcast
     362                l, r = cast_as_datetime(l), cast_as_datetime(r)
     363
     364            for (a, av), (b, bv) in itertools.permutations(((left, l), (right, r))):
     365                if isinstance(a, LT_LTE) and isinstance(b, LT_LTE):
     366                    return left if (av > bv if or_ else av <= bv) else right
     367                if isinstance(a, GT_GTE) and isinstance(b, GT_GTE):
     368                    return left if (av < bv if or_ else av >= bv) else right
     369
     370                # we can't ever shortcut to true because the column could be null
     371                if not or_:
     372                    if isinstance(a, exp.LT) and isinstance(b, GT_GTE):
     373                        if av <= bv:
     374                            return exp.false()
     375                    elif isinstance(a, exp.GT) and isinstance(b, LT_LTE):
     376                        if av >= bv:
     377                            return exp.false()
     378                    elif isinstance(a, exp.EQ):
     379                        if isinstance(b, exp.LT):
     380                            return exp.false() if av >= bv else a
     381                        if isinstance(b, exp.LTE):
     382                            return exp.false() if av > bv else a
     383                        if isinstance(b, exp.GT):
     384                            return exp.false() if av <= bv else a
     385                        if isinstance(b, exp.GTE):
     386                            return exp.false() if av < bv else a
     387                        if isinstance(b, exp.NEQ):
     388                            return exp.false() if av == bv else a
     389    return None
     390
     391
     392def remove_complements(expression, root=True):
     393    """
     394    Removing complements.
     395
     396    A AND NOT A -> FALSE
     397    A OR NOT A -> TRUE
     398    """
     399    if isinstance(expression, AND_OR) and (root or not expression.same_parent):
     400        ops = set(expression.flatten())
     401        for op in ops:
     402            if isinstance(op, exp.Not) and op.this in ops:
     403                return exp.false() if isinstance(expression, exp.And) else exp.true()
     404
     405    return expression
     406
     407
     408def uniq_sort(expression, root=True):
     409    """
     410    Uniq and sort a connector.
     411
     412    C AND A AND B AND B -> A AND B AND C
     413    """
     414    if isinstance(expression, exp.Connector) and (root or not expression.same_parent):
     415        flattened = tuple(expression.flatten())
     416
     417        if isinstance(expression, exp.Xor):
     418            result_func = exp.xor
     419            # Do not deduplicate XOR as A XOR A != A if A == True
     420            deduped = None
     421            arr = tuple((gen(e), e) for e in flattened)
     422        else:
     423            result_func = exp.and_ if isinstance(expression, exp.And) else exp.or_
     424            deduped = {gen(e): e for e in flattened}
     425            arr = tuple(deduped.items())
     426
     427        # check if the operands are already sorted, if not sort them
     428        # A AND C AND B -> A AND B AND C
     429        for i, (sql, e) in enumerate(arr[1:]):
     430            if sql < arr[i][0]:
     431                expression = result_func(*(e for _, e in sorted(arr)), copy=False)
     432                break
     433        else:
     434            # we didn't have to sort but maybe we need to dedup
     435            if deduped and len(deduped) < len(flattened):
     436                expression = result_func(*deduped.values(), copy=False)
     437
     438    return expression
     439
     440
     441def absorb_and_eliminate(expression, root=True):
     442    """
     443    absorption:
     444        A AND (A OR B) -> A
     445        A OR (A AND B) -> A
     446        A AND (NOT A OR B) -> A AND B
     447        A OR (NOT A AND B) -> A OR B
     448    elimination:
     449        (A AND B) OR (A AND NOT B) -> A
     450        (A OR B) AND (A OR NOT B) -> A
     451    """
     452    if isinstance(expression, AND_OR) and (root or not expression.same_parent):
     453        kind = exp.Or if isinstance(expression, exp.And) else exp.And
     454
     455        ops = tuple(expression.flatten())
     456
     457        # Initialize lookup tables:
     458        # Set of all operands, used to find complements for absorption.
     459        op_set = set()
     460        # Sub-operands, used to find subsets for absorption.
     461        subops = defaultdict(list)
     462        # Pairs of complements, used for elimination.
     463        pairs = defaultdict(list)
     464
     465        # Populate the lookup tables
     466        for op in ops:
     467            op_set.add(op)
     468
     469            if not isinstance(op, kind):
     470                # In cases like: A OR (A AND B)
     471                # Subop will be: ^
     472                subops[op].append({op})
     473                continue
     474
     475            # In cases like: (A AND B) OR (A AND B AND C)
     476            # Subops will be: ^     ^
     477            subset = set(op.flatten())
     478            for i in subset:
     479                subops[i].append(subset)
     480
     481            a, b = op.unnest_operands()
     482            if isinstance(a, exp.Not):
     483                pairs[frozenset((a.this, b))].append((op, b))
     484            if isinstance(b, exp.Not):
     485                pairs[frozenset((a, b.this))].append((op, a))
     486
     487        for op in ops:
     488            if not isinstance(op, kind):
     489                continue
     490
     491            a, b = op.unnest_operands()
     492
     493            # Absorb
     494            if isinstance(a, exp.Not) and a.this in op_set:
     495                a.replace(exp.true() if kind == exp.And else exp.false())
     496                continue
     497            if isinstance(b, exp.Not) and b.this in op_set:
     498                b.replace(exp.true() if kind == exp.And else exp.false())
     499                continue
     500            superset = set(op.flatten())
     501            if any(any(subset < superset for subset in subops[i]) for i in superset):
     502                op.replace(exp.false() if kind == exp.And else exp.true())
     503                continue
     504
     505            # Eliminate
     506            for other, complement in pairs[frozenset((a, b))]:
     507                op.replace(complement)
     508                other.replace(complement)
     509
     510    return expression
     511
     512
     513def propagate_constants(expression, root=True):
     514    """
     515    Propagate constants for conjunctions in DNF:
     516
     517    SELECT * FROM t WHERE a = b AND b = 5 becomes
     518    SELECT * FROM t WHERE a = 5 AND b = 5
     519
     520    Reference: https://www.sqlite.org/optoverview.html
     521    """
     522
     523    if (
     524        isinstance(expression, exp.And)
     525        and (root or not expression.same_parent)
     526        and sqlglot.optimizer.normalize.normalized(expression, dnf=True)
     527    ):
     528        constant_mapping = {}
     529        for expr in walk_in_scope(expression, prune=lambda node: isinstance(node, exp.If)):
     530            if isinstance(expr, exp.EQ):
     531                l, r = expr.left, expr.right
     532
     533                # TODO: create a helper that can be used to detect nested literal expressions such
     534                # as CAST(123456 AS BIGINT), since we usually want to treat those as literals too
     535                if isinstance(l, exp.Column) and isinstance(r, exp.Literal):
     536                    constant_mapping[l] = (id(l), r)
     537
     538        if constant_mapping:
     539            for column in find_all_in_scope(expression, exp.Column):
     540                parent = column.parent
     541                column_id, constant = constant_mapping.get(column) or (None, None)
     542                if (
     543                    column_id is not None
     544                    and id(column) != column_id
     545                    and not (isinstance(parent, exp.Is) and isinstance(parent.expression, exp.Null))
     546                ):
     547                    column.replace(constant.copy())
     548
     549    return expression
     550
     551
     552INVERSE_DATE_OPS: t.Dict[t.Type[exp.Expression], t.Type[exp.Expression]] = {
     553    exp.DateAdd: exp.Sub,
     554    exp.DateSub: exp.Add,
     555    exp.DatetimeAdd: exp.Sub,
     556    exp.DatetimeSub: exp.Add,
     557}
     558
     559INVERSE_OPS: t.Dict[t.Type[exp.Expression], t.Type[exp.Expression]] = {
     560    **INVERSE_DATE_OPS,
     561    exp.Add: exp.Sub,
     562    exp.Sub: exp.Add,
     563}
     564
     565
     566def _is_number(expression: exp.Expression) -> bool:
     567    return expression.is_number
     568
     569
     570def _is_interval(expression: exp.Expression) -> bool:
     571    return isinstance(expression, exp.Interval) and extract_interval(expression) is not None
     572
     573
     574@catch(ModuleNotFoundError, UnsupportedUnit)
     575def simplify_equality(expression: exp.Expression) -> exp.Expression:
     576    """
     577    Use the subtraction and addition properties of equality to simplify expressions:
     578
     579        x + 1 = 3 becomes x = 2
     580
     581    There are two binary operations in the above expression: + and =
     582    Here's how we reference all the operands in the code below:
     583
     584          l     r
     585        x + 1 = 3
     586        a   b
     587    """
     588    if isinstance(expression, COMPARISONS):
     589        l, r = expression.left, expression.right
     590
     591        if l.__class__ not in INVERSE_OPS:
     592            return expression
     593
     594        if r.is_number:
     595            a_predicate = _is_number
     596            b_predicate = _is_number
     597        elif _is_date_literal(r):
     598            a_predicate = _is_date_literal
     599            b_predicate = _is_interval
     600        else:
     601            return expression
     602
     603        if l.__class__ in INVERSE_DATE_OPS:
     604            l = t.cast(exp.IntervalOp, l)
     605            a = l.this
     606            b = l.interval()
     607        else:
     608            l = t.cast(exp.Binary, l)
     609            a, b = l.left, l.right
     610
     611        if not a_predicate(a) and b_predicate(b):
     612            pass
     613        elif not a_predicate(b) and b_predicate(a):
     614            a, b = b, a
     615        else:
     616            return expression
     617
     618        return expression.__class__(
     619            this=a, expression=INVERSE_OPS[l.__class__](this=r, expression=b)
     620        )
     621    return expression
     622
     623
     624def simplify_literals(expression, root=True):
     625    if isinstance(expression, exp.Binary) and not isinstance(expression, exp.Connector):
     626        return _flat_simplify(expression, _simplify_binary, root)
     627
     628    if isinstance(expression, exp.Neg) and isinstance(expression.this, exp.Neg):
     629        return expression.this.this
     630
     631    if type(expression) in INVERSE_DATE_OPS:
     632        return _simplify_binary(expression, expression.this, expression.interval()) or expression
     633
     634    return expression
     635
     636
     637NULL_OK = (exp.NullSafeEQ, exp.NullSafeNEQ, exp.PropertyEQ)
     638
     639
     640def _simplify_integer_cast(expr: exp.Expression) -> exp.Expression:
     641    if isinstance(expr, exp.Cast) and isinstance(expr.this, exp.Cast):
     642        this = _simplify_integer_cast(expr.this)
     643    else:
     644        this = expr.this
     645
     646    if isinstance(expr, exp.Cast) and this.is_int:
     647        num = this.to_py()
     648
     649        # Remove the (up)cast from small (byte-sized) integers in predicates which is side-effect free. Downcasts on any
     650        # integer type might cause overflow, thus the cast cannot be eliminated and the behavior is
     651        # engine-dependent
     652        if (
     653            TINYINT_MIN <= num <= TINYINT_MAX and expr.to.this in exp.DataType.SIGNED_INTEGER_TYPES
     654        ) or (
     655            UTINYINT_MIN <= num <= UTINYINT_MAX
     656            and expr.to.this in exp.DataType.UNSIGNED_INTEGER_TYPES
     657        ):
     658            return this
     659
     660    return expr
     661
     662
     663def _simplify_binary(expression, a, b):
     664    if isinstance(expression, COMPARISONS):
     665        a = _simplify_integer_cast(a)
     666        b = _simplify_integer_cast(b)
     667
     668    if isinstance(expression, exp.Is):
     669        if isinstance(b, exp.Not):
     670            c = b.this
     671            not_ = True
     672        else:
     673            c = b
     674            not_ = False
     675
     676        if is_null(c):
     677            if isinstance(a, exp.Literal):
     678                return exp.true() if not_ else exp.false()
     679            if is_null(a):
     680                return exp.false() if not_ else exp.true()
     681    elif isinstance(expression, NULL_OK):
     682        return None
     683    elif is_null(a) or is_null(b):
     684        return exp.null()
     685
     686    if a.is_number and b.is_number:
     687        num_a = a.to_py()
     688        num_b = b.to_py()
     689
     690        if isinstance(expression, exp.Add):
     691            return exp.Literal.number(num_a + num_b)
     692        if isinstance(expression, exp.Mul):
     693            return exp.Literal.number(num_a * num_b)
     694
     695        # We only simplify Sub, Div if a and b have the same parent because they're not associative
     696        if isinstance(expression, exp.Sub):
     697            return exp.Literal.number(num_a - num_b) if a.parent is b.parent else None
     698        if isinstance(expression, exp.Div):
     699            # engines have differing int div behavior so intdiv is not safe
     700            if (isinstance(num_a, int) and isinstance(num_b, int)) or a.parent is not b.parent:
     701                return None
     702            return exp.Literal.number(num_a / num_b)
     703
     704        boolean = eval_boolean(expression, num_a, num_b)
     705
     706        if boolean:
     707            return boolean
     708    elif a.is_string and b.is_string:
     709        boolean = eval_boolean(expression, a.this, b.this)
     710
     711        if boolean:
     712            return boolean
     713    elif _is_date_literal(a) and isinstance(b, exp.Interval):
     714        date, b = extract_date(a), extract_interval(b)
     715        if date and b:
     716            if isinstance(expression, (exp.Add, exp.DateAdd, exp.DatetimeAdd)):
     717                return date_literal(date + b, extract_type(a))
     718            if isinstance(expression, (exp.Sub, exp.DateSub, exp.DatetimeSub)):
     719                return date_literal(date - b, extract_type(a))
     720    elif isinstance(a, exp.Interval) and _is_date_literal(b):
     721        a, date = extract_interval(a), extract_date(b)
     722        # you cannot subtract a date from an interval
     723        if a and b and isinstance(expression, exp.Add):
     724            return date_literal(a + date, extract_type(b))
     725    elif _is_date_literal(a) and _is_date_literal(b):
     726        if isinstance(expression, exp.Predicate):
     727            a, b = extract_date(a), extract_date(b)
     728            boolean = eval_boolean(expression, a, b)
     729            if boolean:
     730                return boolean
     731
     732    return None
     733
     734
     735def simplify_parens(expression):
     736    if not isinstance(expression, exp.Paren):
     737        return expression
     738
     739    this = expression.this
     740    parent = expression.parent
     741    parent_is_predicate = isinstance(parent, exp.Predicate)
     742
     743    if (
     744        not isinstance(this, exp.Select)
     745        and not isinstance(parent, exp.SubqueryPredicate)
     746        and (
     747            not isinstance(parent, (exp.Condition, exp.Binary))
     748            or isinstance(parent, exp.Paren)
     749            or (
     750                not isinstance(this, exp.Binary)
     751                and not (isinstance(this, (exp.Not, exp.Is)) and parent_is_predicate)
     752            )
     753            or (isinstance(this, exp.Predicate) and not parent_is_predicate)
     754            or (isinstance(this, exp.Add) and isinstance(parent, exp.Add))
     755            or (isinstance(this, exp.Mul) and isinstance(parent, exp.Mul))
     756            or (isinstance(this, exp.Mul) and isinstance(parent, (exp.Add, exp.Sub)))
     757        )
     758    ):
     759        return this
     760    return expression
     761
     762
     763def _is_nonnull_constant(expression: exp.Expression) -> bool:
     764    return isinstance(expression, exp.NONNULL_CONSTANTS) or _is_date_literal(expression)
     765
     766
     767def _is_constant(expression: exp.Expression) -> bool:
     768    return isinstance(expression, exp.CONSTANTS) or _is_date_literal(expression)
     769
     770
     771def simplify_coalesce(expression):
     772    # COALESCE(x) -> x
     773    if (
     774        isinstance(expression, exp.Coalesce)
     775        and (not expression.expressions or _is_nonnull_constant(expression.this))
     776        # COALESCE is also used as a Spark partitioning hint
     777        and not isinstance(expression.parent, exp.Hint)
     778    ):
     779        return expression.this
     780
     781    if not isinstance(expression, COMPARISONS):
     782        return expression
     783
     784    if isinstance(expression.left, exp.Coalesce):
     785        coalesce = expression.left
     786        other = expression.right
     787    elif isinstance(expression.right, exp.Coalesce):
     788        coalesce = expression.right
     789        other = expression.left
     790    else:
     791        return expression
     792
     793    # This transformation is valid for non-constants,
     794    # but it really only does anything if they are both constants.
     795    if not _is_constant(other):
     796        return expression
     797
     798    # Find the first constant arg
     799    for arg_index, arg in enumerate(coalesce.expressions):
     800        if _is_constant(arg):
     801            break
     802    else:
     803        return expression
     804
     805    coalesce.set("expressions", coalesce.expressions[:arg_index])
     806
     807    # Remove the COALESCE function. This is an optimization, skipping a simplify iteration,
     808    # since we already remove COALESCE at the top of this function.
     809    coalesce = coalesce if coalesce.expressions else coalesce.this
     810
     811    # This expression is more complex than when we started, but it will get simplified further
     812    return exp.paren(
     813        exp.or_(
     814            exp.and_(
     815                coalesce.is_(exp.null()).not_(copy=False),
     816                expression.copy(),
     817                copy=False,
     818            ),
     819            exp.and_(
     820                coalesce.is_(exp.null()),
     821                type(expression)(this=arg.copy(), expression=other.copy()),
     822                copy=False,
     823            ),
     824            copy=False,
     825        )
     826    )
     827
     828
     829CONCATS = (exp.Concat, exp.DPipe)
     830
     831
     832def simplify_concat(expression):
     833    """Reduces all groups that contain string literals by concatenating them."""
     834    if not isinstance(expression, CONCATS) or (
     835        # We can't reduce a CONCAT_WS call if we don't statically know the separator
     836        isinstance(expression, exp.ConcatWs) and not expression.expressions[0].is_string
     837    ):
     838        return expression
     839
     840    if isinstance(expression, exp.ConcatWs):
     841        sep_expr, *expressions = expression.expressions
     842        sep = sep_expr.name
     843        concat_type = exp.ConcatWs
     844        args = {}
     845    else:
     846        expressions = expression.expressions
     847        sep = ""
     848        concat_type = exp.Concat
     849        args = {
     850            "safe": expression.args.get("safe"),
     851            "coalesce": expression.args.get("coalesce"),
     852        }
     853
     854    new_args = []
     855    for is_string_group, group in itertools.groupby(
     856        expressions or expression.flatten(), lambda e: e.is_string
     857    ):
     858        if is_string_group:
     859            new_args.append(exp.Literal.string(sep.join(string.name for string in group)))
     860        else:
     861            new_args.extend(group)
     862
     863    if len(new_args) == 1 and new_args[0].is_string:
     864        return new_args[0]
     865
     866    if concat_type is exp.ConcatWs:
     867        new_args = [sep_expr] + new_args
     868    elif isinstance(expression, exp.DPipe):
     869        return reduce(lambda x, y: exp.DPipe(this=x, expression=y), new_args)
     870
     871    return concat_type(expressions=new_args, **args)
     872
     873
     874def simplify_conditionals(expression):
     875    """Simplifies expressions like IF, CASE if their condition is statically known."""
     876    if isinstance(expression, exp.Case):
     877        this = expression.this
     878        for case in expression.args["ifs"]:
     879            cond = case.this
     880            if this:
     881                # Convert CASE x WHEN matching_value ... to CASE WHEN x = matching_value ...
     882                cond = cond.replace(this.pop().eq(cond))
     883
     884            if always_true(cond):
     885                return case.args["true"]
     886
     887            if always_false(cond):
     888                case.pop()
     889                if not expression.args["ifs"]:
     890                    return expression.args.get("default") or exp.null()
     891    elif isinstance(expression, exp.If) and not isinstance(expression.parent, exp.Case):
     892        if always_true(expression.this):
     893            return expression.args["true"]
     894        if always_false(expression.this):
     895            return expression.args.get("false") or exp.null()
     896
     897    return expression
     898
     899
     900def simplify_startswith(expression: exp.Expression) -> exp.Expression:
     901    """
     902    Reduces a prefix check to either TRUE or FALSE if both the string and the
     903    prefix are statically known.
     904
     905    Example:
     906        >>> from sqlglot import parse_one
     907        >>> simplify_startswith(parse_one("STARTSWITH('foo', 'f')")).sql()
     908        'TRUE'
     909    """
     910    if (
     911        isinstance(expression, exp.StartsWith)
     912        and expression.this.is_string
     913        and expression.expression.is_string
     914    ):
     915        return exp.convert(expression.name.startswith(expression.expression.name))
     916
     917    return expression
     918
     919
     920DateRange = t.Tuple[datetime.date, datetime.date]
     921
     922
     923def _datetrunc_range(date: datetime.date, unit: str, dialect: Dialect) -> t.Optional[DateRange]:
     924    """
     925    Get the date range for a DATE_TRUNC equality comparison:
     926
     927    Example:
     928        _datetrunc_range(date(2021-01-01), 'year') == (date(2021-01-01), date(2022-01-01))
     929    Returns:
     930        tuple of [min, max) or None if a value can never be equal to `date` for `unit`
     931    """
     932    floor = date_floor(date, unit, dialect)
     933
     934    if date != floor:
     935        # This will always be False, except for NULL values.
     936        return None
     937
     938    return floor, floor + interval(unit)
     939
     940
     941def _datetrunc_eq_expression(
     942    left: exp.Expression, drange: DateRange, target_type: t.Optional[exp.DataType]
     943) -> exp.Expression:
     944    """Get the logical expression for a date range"""
     945    return exp.and_(
     946        left >= date_literal(drange[0], target_type),
     947        left < date_literal(drange[1], target_type),
     948        copy=False,
     949    )
     950
     951
     952def _datetrunc_eq(
     953    left: exp.Expression,
     954    date: datetime.date,
     955    unit: str,
     956    dialect: Dialect,
     957    target_type: t.Optional[exp.DataType],
     958) -> t.Optional[exp.Expression]:
     959    drange = _datetrunc_range(date, unit, dialect)
     960    if not drange:
     961        return None
     962
     963    return _datetrunc_eq_expression(left, drange, target_type)
     964
     965
     966def _datetrunc_neq(
     967    left: exp.Expression,
     968    date: datetime.date,
     969    unit: str,
     970    dialect: Dialect,
     971    target_type: t.Optional[exp.DataType],
     972) -> t.Optional[exp.Expression]:
     973    drange = _datetrunc_range(date, unit, dialect)
     974    if not drange:
     975        return None
     976
     977    return exp.and_(
     978        left < date_literal(drange[0], target_type),
     979        left >= date_literal(drange[1], target_type),
     980        copy=False,
     981    )
     982
     983
     984DATETRUNC_BINARY_COMPARISONS: t.Dict[t.Type[exp.Expression], DateTruncBinaryTransform] = {
     985    exp.LT: lambda l, dt, u, d, t: l
     986    < date_literal(dt if dt == date_floor(dt, u, d) else date_floor(dt, u, d) + interval(u), t),
     987    exp.GT: lambda l, dt, u, d, t: l >= date_literal(date_floor(dt, u, d) + interval(u), t),
     988    exp.LTE: lambda l, dt, u, d, t: l < date_literal(date_floor(dt, u, d) + interval(u), t),
     989    exp.GTE: lambda l, dt, u, d, t: l >= date_literal(date_ceil(dt, u, d), t),
     990    exp.EQ: _datetrunc_eq,
     991    exp.NEQ: _datetrunc_neq,
     992}
     993DATETRUNC_COMPARISONS = {exp.In, *DATETRUNC_BINARY_COMPARISONS}
     994DATETRUNCS = (exp.DateTrunc, exp.TimestampTrunc)
     995
     996
     997def _is_datetrunc_predicate(left: exp.Expression, right: exp.Expression) -> bool:
     998    return isinstance(left, DATETRUNCS) and _is_date_literal(right)
     999
    1000
    1001@catch(ModuleNotFoundError, UnsupportedUnit)
    1002def simplify_datetrunc(expression: exp.Expression, dialect: Dialect) -> exp.Expression:
    1003    """Simplify expressions like `DATE_TRUNC('year', x) >= CAST('2021-01-01' AS DATE)`"""
    1004    comparison = expression.__class__
    1005
    1006    if isinstance(expression, DATETRUNCS):
    1007        this = expression.this
    1008        trunc_type = extract_type(this)
    1009        date = extract_date(this)
    1010        if date and expression.unit:
    1011            return date_literal(date_floor(date, expression.unit.name.lower(), dialect), trunc_type)
    1012    elif comparison not in DATETRUNC_COMPARISONS:
    1013        return expression
    1014
    1015    if isinstance(expression, exp.Binary):
    1016        l, r = expression.left, expression.right
    1017
    1018        if not _is_datetrunc_predicate(l, r):
    1019            return expression
    1020
    1021        l = t.cast(exp.DateTrunc, l)
    1022        trunc_arg = l.this
    1023        unit = l.unit.name.lower()
    1024        date = extract_date(r)
    1025
    1026        if not date:
    1027            return expression
    1028
    1029        return (
    1030            DATETRUNC_BINARY_COMPARISONS[comparison](
    1031                trunc_arg, date, unit, dialect, extract_type(r)
    1032            )
    1033            or expression
    1034        )
    1035
    1036    if isinstance(expression, exp.In):
    1037        l = expression.this
    1038        rs = expression.expressions
    1039
    1040        if rs and all(_is_datetrunc_predicate(l, r) for r in rs):
    1041            l = t.cast(exp.DateTrunc, l)
    1042            unit = l.unit.name.lower()
    1043
    1044            ranges = []
    1045            for r in rs:
    1046                date = extract_date(r)
    1047                if not date:
    1048                    return expression
    1049                drange = _datetrunc_range(date, unit, dialect)
    1050                if drange:
    1051                    ranges.append(drange)
    1052
    1053            if not ranges:
    1054                return expression
    1055
    1056            ranges = merge_ranges(ranges)
    1057            target_type = extract_type(*rs)
    1058
    1059            return exp.or_(
    1060                *[_datetrunc_eq_expression(l, drange, target_type) for drange in ranges], copy=False
    1061            )
    1062
    1063    return expression
    1064
    1065
    1066def sort_comparison(expression: exp.Expression) -> exp.Expression:
    1067    if expression.__class__ in COMPLEMENT_COMPARISONS:
    1068        l, r = expression.this, expression.expression
    1069        l_column = isinstance(l, exp.Column)
    1070        r_column = isinstance(r, exp.Column)
    1071        l_const = _is_constant(l)
    1072        r_const = _is_constant(r)
    1073
    1074        if (l_column and not r_column) or (r_const and not l_const):
    1075            return expression
    1076        if (r_column and not l_column) or (l_const and not r_const) or (gen(l) > gen(r)):
    1077            return INVERSE_COMPARISONS.get(expression.__class__, expression.__class__)(
    1078                this=r, expression=l
    1079            )
    1080    return expression
    1081
    1082
    1083# CROSS joins result in an empty table if the right table is empty.
    1084# So we can only simplify certain types of joins to CROSS.
    1085# Or in other words, LEFT JOIN x ON TRUE != CROSS JOIN x
    1086JOINS = {
    1087    ("", ""),
    1088    ("", "INNER"),
    1089    ("RIGHT", ""),
    1090    ("RIGHT", "OUTER"),
    1091}
    1092
    1093
    1094def remove_where_true(expression):
    1095    for where in expression.find_all(exp.Where):
    1096        if always_true(where.this):
    1097            where.pop()
    1098    for join in expression.find_all(exp.Join):
    1099        if (
    1100            always_true(join.args.get("on"))
    1101            and not join.args.get("using")
    1102            and not join.args.get("method")
    1103            and (join.side, join.kind) in JOINS
    1104        ):
    1105            join.args["on"].pop()
    1106            join.set("side", None)
    1107            join.set("kind", "CROSS")
    1108
    1109
    1110def always_true(expression):
    1111    return (isinstance(expression, exp.Boolean) and expression.this) or isinstance(
    1112        expression, exp.Literal
    1113    )
    1114
    1115
    1116def always_false(expression):
    1117    return is_false(expression) or is_null(expression)
    1118
    1119
    1120def is_complement(a, b):
    1121    return isinstance(b, exp.Not) and b.this == a
    1122
    1123
    1124def is_false(a: exp.Expression) -> bool:
    1125    return type(a) is exp.Boolean and not a.this
    1126
    1127
    1128def is_null(a: exp.Expression) -> bool:
    1129    return type(a) is exp.Null
    1130
    1131
    1132def eval_boolean(expression, a, b):
    1133    if isinstance(expression, (exp.EQ, exp.Is)):
    1134        return boolean_literal(a == b)
    1135    if isinstance(expression, exp.NEQ):
    1136        return boolean_literal(a != b)
    1137    if isinstance(expression, exp.GT):
    1138        return boolean_literal(a > b)
    1139    if isinstance(expression, exp.GTE):
    1140        return boolean_literal(a >= b)
    1141    if isinstance(expression, exp.LT):
    1142        return boolean_literal(a < b)
    1143    if isinstance(expression, exp.LTE):
    1144        return boolean_literal(a <= b)
    1145    return None
    1146
    1147
    1148def cast_as_date(value: t.Any) -> t.Optional[datetime.date]:
    1149    if isinstance(value, datetime.datetime):
    1150        return value.date()
    1151    if isinstance(value, datetime.date):
    1152        return value
    1153    try:
    1154        return datetime.datetime.fromisoformat(value).date()
    1155    except ValueError:
    1156        return None
    1157
    1158
    1159def cast_as_datetime(value: t.Any) -> t.Optional[datetime.datetime]:
    1160    if isinstance(value, datetime.datetime):
    1161        return value
    1162    if isinstance(value, datetime.date):
    1163        return datetime.datetime(year=value.year, month=value.month, day=value.day)
    1164    try:
    1165        return datetime.datetime.fromisoformat(value)
    1166    except ValueError:
    1167        return None
    1168
    1169
    1170def cast_value(value: t.Any, to: exp.DataType) -> t.Optional[t.Union[datetime.date, datetime.date]]:
    1171    if not value:
    1172        return None
    1173    if to.is_type(exp.DataType.Type.DATE):
    1174        return cast_as_date(value)
    1175    if to.is_type(*exp.DataType.TEMPORAL_TYPES):
    1176        return cast_as_datetime(value)
    1177    return None
    1178
    1179
    1180def extract_date(cast: exp.Expression) -> t.Optional[t.Union[datetime.date, datetime.date]]:
    1181    if isinstance(cast, exp.Cast):
    1182        to = cast.to
    1183    elif isinstance(cast, exp.TsOrDsToDate) and not cast.args.get("format"):
    1184        to = exp.DataType.build(exp.DataType.Type.DATE)
    1185    else:
    1186        return None
    1187
    1188    if isinstance(cast.this, exp.Literal):
    1189        value: t.Any = cast.this.name
    1190    elif isinstance(cast.this, (exp.Cast, exp.TsOrDsToDate)):
    1191        value = extract_date(cast.this)
    1192    else:
    1193        return None
    1194    return cast_value(value, to)
    1195
    1196
    1197def _is_date_literal(expression: exp.Expression) -> bool:
    1198    return extract_date(expression) is not None
    1199
    1200
    1201def extract_interval(expression):
    1202    try:
    1203        n = int(expression.this.to_py())
    1204        unit = expression.text("unit").lower()
    1205        return interval(unit, n)
    1206    except (UnsupportedUnit, ModuleNotFoundError, ValueError):
    1207        return None
    1208
    1209
    1210def extract_type(*expressions):
    1211    target_type = None
    1212    for expression in expressions:
    1213        target_type = expression.to if isinstance(expression, exp.Cast) else expression.type
    1214        if target_type:
    1215            break
    1216
    1217    return target_type
    1218
    1219
    1220def date_literal(date, target_type=None):
    1221    if not target_type or not target_type.is_type(*exp.DataType.TEMPORAL_TYPES):
    1222        target_type = (
    1223            exp.DataType.Type.DATETIME
    1224            if isinstance(date, datetime.datetime)
    1225            else exp.DataType.Type.DATE
    1226        )
    1227
    1228    return exp.cast(exp.Literal.string(date), target_type)
    1229
    1230
    1231def interval(unit: str, n: int = 1):
    1232    from dateutil.relativedelta import relativedelta
    1233
    1234    if unit == "year":
    1235        return relativedelta(years=1 * n)
    1236    if unit == "quarter":
    1237        return relativedelta(months=3 * n)
    1238    if unit == "month":
    1239        return relativedelta(months=1 * n)
    1240    if unit == "week":
    1241        return relativedelta(weeks=1 * n)
    1242    if unit == "day":
    1243        return relativedelta(days=1 * n)
    1244    if unit == "hour":
    1245        return relativedelta(hours=1 * n)
    1246    if unit == "minute":
    1247        return relativedelta(minutes=1 * n)
    1248    if unit == "second":
    1249        return relativedelta(seconds=1 * n)
    1250
    1251    raise UnsupportedUnit(f"Unsupported unit: {unit}")
    1252
    1253
    1254def date_floor(d: datetime.date, unit: str, dialect: Dialect) -> datetime.date:
    1255    if unit == "year":
    1256        return d.replace(month=1, day=1)
    1257    if unit == "quarter":
    1258        if d.month <= 3:
    1259            return d.replace(month=1, day=1)
    1260        elif d.month <= 6:
    1261            return d.replace(month=4, day=1)
    1262        elif d.month <= 9:
    1263            return d.replace(month=7, day=1)
    1264        else:
    1265            return d.replace(month=10, day=1)
    1266    if unit == "month":
    1267        return d.replace(month=d.month, day=1)
    1268    if unit == "week":
    1269        # Assuming week starts on Monday (0) and ends on Sunday (6)
    1270        return d - datetime.timedelta(days=d.weekday() - dialect.WEEK_OFFSET)
    1271    if unit == "day":
    1272        return d
    1273
    1274    raise UnsupportedUnit(f"Unsupported unit: {unit}")
    1275
    1276
    1277def date_ceil(d: datetime.date, unit: str, dialect: Dialect) -> datetime.date:
    1278    floor = date_floor(d, unit, dialect)
    1279
    1280    if floor == d:
    1281        return d
    1282
    1283    return floor + interval(unit)
    1284
    1285
    1286def boolean_literal(condition):
    1287    return exp.true() if condition else exp.false()
    1288
    1289
    1290def _flat_simplify(expression, simplifier, root=True):
    1291    if root or not expression.same_parent:
    1292        operands = []
    1293        queue = deque(expression.flatten(unnest=False))
    1294        size = len(queue)
    1295
    1296        while queue:
    1297            a = queue.popleft()
    1298
    1299            for b in queue:
    1300                result = simplifier(expression, a, b)
    1301
    1302                if result and result is not expression:
    1303                    queue.remove(b)
    1304                    queue.appendleft(result)
    1305                    break
    1306            else:
    1307                operands.append(a)
    1308
    1309        if len(operands) < size:
    1310            return functools.reduce(
    1311                lambda a, b: expression.__class__(this=a, expression=b), operands
    1312            )
    1313    return expression
    1314
    1315
    1316def gen(expression: t.Any) -> str:
    1317    """Simple pseudo sql generator for quickly generating sortable and uniq strings.
    1318
    1319    Sorting and deduping sql is a necessary step for optimization. Calling the actual
    1320    generator is expensive so we have a bare minimum sql generator here.
    1321    """
    1322    return Gen().gen(expression)
    1323
    1324
    1325class Gen:
    1326    def __init__(self):
    1327        self.stack = []
    1328        self.sqls = []
    1329
    1330    def gen(self, expression: exp.Expression) -> str:
    1331        self.stack = [expression]
    1332        self.sqls.clear()
    1333
    1334        while self.stack:
    1335            node = self.stack.pop()
    1336
    1337            if isinstance(node, exp.Expression):
    1338                exp_handler_name = f"{node.key}_sql"
    1339
    1340                if hasattr(self, exp_handler_name):
    1341                    getattr(self, exp_handler_name)(node)
    1342                elif isinstance(node, exp.Func):
    1343                    self._function(node)
    1344                else:
    1345                    key = node.key.upper()
    1346                    self.stack.append(f"{key} " if self._args(node) else key)
    1347            elif type(node) is list:
    1348                for n in reversed(node):
    1349                    if n is not None:
    1350                        self.stack.extend((n, ","))
    1351                if node:
    1352                    self.stack.pop()
    1353            else:
    1354                if node is not None:
    1355                    self.sqls.append(str(node))
    1356
    1357        return "".join(self.sqls)
    1358
    1359    def add_sql(self, e: exp.Add) -> None:
    1360        self._binary(e, " + ")
    1361
    1362    def alias_sql(self, e: exp.Alias) -> None:
    1363        self.stack.extend(
    1364            (
    1365                e.args.get("alias"),
    1366                " AS ",
    1367                e.args.get("this"),
    1368            )
    1369        )
    1370
    1371    def and_sql(self, e: exp.And) -> None:
    1372        self._binary(e, " AND ")
    1373
    1374    def anonymous_sql(self, e: exp.Anonymous) -> None:
    1375        this = e.this
    1376        if isinstance(this, str):
    1377            name = this.upper()
    1378        elif isinstance(this, exp.Identifier):
    1379            name = this.this
    1380            name = f'"{name}"' if this.quoted else name.upper()
    1381        else:
    1382            raise ValueError(
    1383                f"Anonymous.this expects a str or an Identifier, got '{this.__class__.__name__}'."
    1384            )
    1385
    1386        self.stack.extend(
    1387            (
    1388                ")",
    1389                e.expressions,
    1390                "(",
    1391                name,
    1392            )
    1393        )
    1394
    1395    def between_sql(self, e: exp.Between) -> None:
    1396        self.stack.extend(
    1397            (
    1398                e.args.get("high"),
    1399                " AND ",
    1400                e.args.get("low"),
    1401                " BETWEEN ",
    1402                e.this,
    1403            )
    1404        )
    1405
    1406    def boolean_sql(self, e: exp.Boolean) -> None:
    1407        self.stack.append("TRUE" if e.this else "FALSE")
    1408
    1409    def bracket_sql(self, e: exp.Bracket) -> None:
    1410        self.stack.extend(
    1411            (
    1412                "]",
    1413                e.expressions,
    1414                "[",
    1415                e.this,
    1416            )
    1417        )
    1418
    1419    def column_sql(self, e: exp.Column) -> None:
    1420        for p in reversed(e.parts):
    1421            self.stack.extend((p, "."))
    1422        self.stack.pop()
    1423
    1424    def datatype_sql(self, e: exp.DataType) -> None:
    1425        self._args(e, 1)
    1426        self.stack.append(f"{e.this.name} ")
    1427
    1428    def div_sql(self, e: exp.Div) -> None:
    1429        self._binary(e, " / ")
    1430
    1431    def dot_sql(self, e: exp.Dot) -> None:
    1432        self._binary(e, ".")
    1433
    1434    def eq_sql(self, e: exp.EQ) -> None:
    1435        self._binary(e, " = ")
    1436
    1437    def from_sql(self, e: exp.From) -> None:
    1438        self.stack.extend((e.this, "FROM "))
    1439
    1440    def gt_sql(self, e: exp.GT) -> None:
    1441        self._binary(e, " > ")
    1442
    1443    def gte_sql(self, e: exp.GTE) -> None:
    1444        self._binary(e, " >= ")
    1445
    1446    def identifier_sql(self, e: exp.Identifier) -> None:
    1447        self.stack.append(f'"{e.this}"' if e.quoted else e.this)
    1448
    1449    def ilike_sql(self, e: exp.ILike) -> None:
    1450        self._binary(e, " ILIKE ")
    1451
    1452    def in_sql(self, e: exp.In) -> None:
    1453        self.stack.append(")")
    1454        self._args(e, 1)
    1455        self.stack.extend(
    1456            (
    1457                "(",
    1458                " IN ",
    1459                e.this,
    1460            )
    1461        )
    1462
    1463    def intdiv_sql(self, e: exp.IntDiv) -> None:
    1464        self._binary(e, " DIV ")
    1465
    1466    def is_sql(self, e: exp.Is) -> None:
    1467        self._binary(e, " IS ")
    1468
    1469    def like_sql(self, e: exp.Like) -> None:
    1470        self._binary(e, " Like ")
    1471
    1472    def literal_sql(self, e: exp.Literal) -> None:
    1473        self.stack.append(f"'{e.this}'" if e.is_string else e.this)
    1474
    1475    def lt_sql(self, e: exp.LT) -> None:
    1476        self._binary(e, " < ")
    1477
    1478    def lte_sql(self, e: exp.LTE) -> None:
    1479        self._binary(e, " <= ")
    1480
    1481    def mod_sql(self, e: exp.Mod) -> None:
    1482        self._binary(e, " % ")
    1483
    1484    def mul_sql(self, e: exp.Mul) -> None:
    1485        self._binary(e, " * ")
    1486
    1487    def neg_sql(self, e: exp.Neg) -> None:
    1488        self._unary(e, "-")
    1489
    1490    def neq_sql(self, e: exp.NEQ) -> None:
    1491        self._binary(e, " <> ")
    1492
    1493    def not_sql(self, e: exp.Not) -> None:
    1494        self._unary(e, "NOT ")
    1495
    1496    def null_sql(self, e: exp.Null) -> None:
    1497        self.stack.append("NULL")
    1498
    1499    def or_sql(self, e: exp.Or) -> None:
    1500        self._binary(e, " OR ")
    1501
    1502    def paren_sql(self, e: exp.Paren) -> None:
    1503        self.stack.extend(
    1504            (
    1505                ")",
    1506                e.this,
    1507                "(",
    1508            )
    1509        )
    1510
    1511    def sub_sql(self, e: exp.Sub) -> None:
    1512        self._binary(e, " - ")
    1513
    1514    def subquery_sql(self, e: exp.Subquery) -> None:
    1515        self._args(e, 2)
    1516        alias = e.args.get("alias")
    1517        if alias:
    1518            self.stack.append(alias)
    1519        self.stack.extend((")", e.this, "("))
    1520
    1521    def table_sql(self, e: exp.Table) -> None:
    1522        self._args(e, 4)
    1523        alias = e.args.get("alias")
    1524        if alias:
    1525            self.stack.append(alias)
    1526        for p in reversed(e.parts):
    1527            self.stack.extend((p, "."))
    1528        self.stack.pop()
    1529
    1530    def tablealias_sql(self, e: exp.TableAlias) -> None:
    1531        columns = e.columns
    1532
    1533        if columns:
    1534            self.stack.extend((")", columns, "("))
    1535
    1536        self.stack.extend((e.this, " AS "))
    1537
    1538    def var_sql(self, e: exp.Var) -> None:
    1539        self.stack.append(e.this)
    1540
    1541    def _binary(self, e: exp.Binary, op: str) -> None:
    1542        self.stack.extend((e.expression, op, e.this))
    1543
    1544    def _unary(self, e: exp.Unary, op: str) -> None:
    1545        self.stack.extend((e.this, op))
    1546
    1547    def _function(self, e: exp.Func) -> None:
    1548        self.stack.extend(
    1549            (
    1550                ")",
    1551                list(e.args.values()),
    1552                "(",
    1553                e.sql_name(),
    1554            )
    1555        )
    1556
    1557    def _args(self, node: exp.Expression, arg_index: int = 0) -> bool:
    1558        kvs = []
    1559        arg_types = list(node.arg_types)[arg_index:] if arg_index else node.arg_types
    1560
    1561        for k in arg_types or arg_types:
    1562            v = node.args.get(k)
    1563
    1564            if v is not None:
    1565                kvs.append([f":{k}", v])
    1566        if kvs:
    1567            self.stack.append(kvs)
    1568            return True
    1569        return False

logger = <Logger sqlglot (WARNING)>
FINAL = 'final'
TINYINT_MIN = -128
TINYINT_MAX = 127
UTINYINT_MIN = 0
UTINYINT_MAX = 255
class UnsupportedUnit(builtins.Exception): View Source

    36class UnsupportedUnit(Exception):
    37    pass

Common base class for all non-exit exceptions.

##### Inherited Members

builtins.Exception
  Exception
builtins.BaseException
  with_traceback
  args

def simplify( expression: sqlglot.expressions.Expression, constant_propagation: bool = False, dialect: Union[str, sqlglot.dialects.dialect.Dialect, Type[sqlglot.dialects.dialect.Dialect], NoneType] = None, max_depth: Optional[int] = None): View Source

     40def simplify(
     41    expression: exp.Expression,
     42    constant_propagation: bool = False,
     43    dialect: DialectType = None,
     44    max_depth: t.Optional[int] = None,
     45):
     46    """
     47    Rewrite sqlglot AST to simplify expressions.
     48
     49    Example:
     50        >>> import sqlglot
     51        >>> expression = sqlglot.parse_one("TRUE AND TRUE")
     52        >>> simplify(expression).sql()
     53        'TRUE'
     54
     55    Args:
     56        expression: expression to simplify
     57        constant_propagation: whether the constant propagation rule should be used
     58        max_depth: Chains of Connectors (AND, OR, etc) exceeding `max_depth` will be skipped
     59    Returns:
     60        sqlglot.Expression: simplified expression
     61    """
     62
     63    dialect = Dialect.get_or_raise(dialect)
     64
     65    def _simplify(expression, root=True):
     66        if (
     67            max_depth
     68            and isinstance(expression, exp.Connector)
     69            and not isinstance(expression.parent, exp.Connector)
     70        ):
     71            depth = connector_depth(expression)
     72            if depth > max_depth:
     73                logger.info(
     74                    f"Skipping simplification because connector depth {depth} exceeds max {max_depth}"
     75                )
     76                return expression
     77
     78        if expression.meta.get(FINAL):
     79            return expression
     80
     81        # group by expressions cannot be simplified, for example
     82        # select x + 1 + 1 FROM y GROUP BY x + 1 + 1
     83        # the projection must exactly match the group by key
     84        group = expression.args.get("group")
     85
     86        if group and hasattr(expression, "selects"):
     87            groups = set(group.expressions)
     88            group.meta[FINAL] = True
     89
     90            for e in expression.selects:
     91                for node in e.walk():
     92                    if node in groups:
     93                        e.meta[FINAL] = True
     94                        break
     95
     96            having = expression.args.get("having")
     97            if having:
     98                for node in having.walk():
     99                    if node in groups:
    100                        having.meta[FINAL] = True
    101                        break
    102
    103        # Pre-order transformations
    104        node = expression
    105        node = rewrite_between(node)
    106        node = uniq_sort(node, root)
    107        node = absorb_and_eliminate(node, root)
    108        node = simplify_concat(node)
    109        node = simplify_conditionals(node)
    110
    111        if constant_propagation:
    112            node = propagate_constants(node, root)
    113
    114        exp.replace_children(node, lambda e: _simplify(e, False))
    115
    116        # Post-order transformations
    117        node = simplify_not(node)
    118        node = flatten(node)
    119        node = simplify_connectors(node, root)
    120        node = remove_complements(node, root)
    121        node = simplify_coalesce(node)
    122        node.parent = expression.parent
    123        node = simplify_literals(node, root)
    124        node = simplify_equality(node)
    125        node = simplify_parens(node)
    126        node = simplify_datetrunc(node, dialect)
    127        node = sort_comparison(node)
    128        node = simplify_startswith(node)
    129
    130        if root:
    131            expression.replace(node)
    132        return node
    133
    134    expression = while_changing(expression, _simplify)
    135    remove_where_true(expression)
    136    return expression

Rewrite sqlglot AST to simplify expressions.

###### Example:

>     >>> import sqlglot
>     >>> expression = sqlglot.parse_one("TRUE AND TRUE")
>     >>> simplify(expression).sql()
>     'TRUE'

###### Arguments:

- expression: expression to simplify
- constant_propagation: whether the constant propagation rule should be used
- max_depth: Chains of Connectors (AND, OR, etc) exceeding `max_depth` will be skipped

###### Returns:

> sqlglot.Expression: simplified expression

def connector_depth(expression: sqlglot.expressions.Expression) -> int: View Source

    139def connector_depth(expression: exp.Expression) -> int:
    140    """
    141    Determine the maximum depth of a tree of Connectors.
    142
    143    For example:
    144        >>> from sqlglot import parse_one
    145        >>> connector_depth(parse_one("a AND b AND c AND d"))
    146        3
    147    """
    148    stack = deque([(expression, 0)])
    149    max_depth = 0
    150
    151    while stack:
    152        expression, depth = stack.pop()
    153
    154        if not isinstance(expression, exp.Connector):
    155            continue
    156
    157        depth += 1
    158        max_depth = max(depth, max_depth)
    159
    160        stack.append((expression.left, depth))
    161        stack.append((expression.right, depth))
    162
    163    return max_depth

Determine the maximum depth of a tree of Connectors.

###### For example:

>     >>> from sqlglot import parse_one
>     >>> connector_depth(parse_one("a AND b AND c AND d"))
>     3

def catch(*exceptions): View Source

    166def catch(*exceptions):
    167    """Decorator that ignores a simplification function if any of `exceptions` are raised"""
    168
    169    def decorator(func):
    170        def wrapped(expression, *args, **kwargs):
    171            try:
    172                return func(expression, *args, **kwargs)
    173            except exceptions:
    174                return expression
    175
    176        return wrapped
    177
    178    return decorator

Decorator that ignores a simplification function if any of `exceptions` are raised

def rewrite_between( expression: sqlglot.expressions.Expression) -> sqlglot.expressions.Expression: View Source

    181def rewrite_between(expression: exp.Expression) -> exp.Expression:
    182    """Rewrite x between y and z to x >= y AND x <= z.
    183
    184    This is done because comparison simplification is only done on lt/lte/gt/gte.
    185    """
    186    if isinstance(expression, exp.Between):
    187        negate = isinstance(expression.parent, exp.Not)
    188
    189        expression = exp.and_(
    190            exp.GTE(this=expression.this.copy(), expression=expression.args["low"]),
    191            exp.LTE(this=expression.this.copy(), expression=expression.args["high"]),
    192            copy=False,
    193        )
    194
    195        if negate:
    196            expression = exp.paren(expression, copy=False)
    197
    198    return expression

Rewrite x between y and z to x >= y AND x <= z.

This is done because comparison simplification is only done on lt/lte/gt/gte.

COMPLEMENT_COMPARISONS = {<class 'sqlglot.expressions.LT'>: <class 'sqlglot.expressions.GTE'>, <class 'sqlglot.expressions.GT'>: <class 'sqlglot.expressions.LTE'>, <class 'sqlglot.expressions.LTE'>: <class 'sqlglot.expressions.GT'>, <class 'sqlglot.expressions.GTE'>: <class 'sqlglot.expressions.LT'>, <class 'sqlglot.expressions.EQ'>: <class 'sqlglot.expressions.NEQ'>, <class 'sqlglot.expressions.NEQ'>: <class 'sqlglot.expressions.EQ'>}
def simplify_not(expression): View Source

    211def simplify_not(expression):
    212    """
    213    Demorgan's Law
    214    NOT (x OR y) -> NOT x AND NOT y
    215    NOT (x AND y) -> NOT x OR NOT y
    216    """
    217    if isinstance(expression, exp.Not):
    218        this = expression.this
    219        if is_null(this):
    220            return exp.null()
    221        if this.__class__ in COMPLEMENT_COMPARISONS:
    222            return COMPLEMENT_COMPARISONS[this.__class__](
    223                this=this.this, expression=this.expression
    224            )
    225        if isinstance(this, exp.Paren):
    226            condition = this.unnest()
    227            if isinstance(condition, exp.And):
    228                return exp.paren(
    229                    exp.or_(
    230                        exp.not_(condition.left, copy=False),
    231                        exp.not_(condition.right, copy=False),
    232                        copy=False,
    233                    )
    234                )
    235            if isinstance(condition, exp.Or):
    236                return exp.paren(
    237                    exp.and_(
    238                        exp.not_(condition.left, copy=False),
    239                        exp.not_(condition.right, copy=False),
    240                        copy=False,
    241                    )
    242                )
    243            if is_null(condition):
    244                return exp.null()
    245        if always_true(this):
    246            return exp.false()
    247        if is_false(this):
    248            return exp.true()
    249        if isinstance(this, exp.Not):
    250            # double negation
    251            # NOT NOT x -> x
    252            return this.this
    253    return expression

Demorgan's Law NOT (x OR y) -> NOT x AND NOT y NOT (x AND y) -> NOT x OR NOT y

def flatten(expression): View Source

    256def flatten(expression):
    257    """
    258    A AND (B AND C) -> A AND B AND C
    259    A OR (B OR C) -> A OR B OR C
    260    """
    261    if isinstance(expression, exp.Connector):
    262        for node in expression.args.values():
    263            child = node.unnest()
    264            if isinstance(child, expression.__class__):
    265                node.replace(child)
    266    return expression

A AND (B AND C) -> A AND B AND C A OR (B OR C) -> A OR B OR C

def simplify_connectors(expression, root=True): View Source

    269def simplify_connectors(expression, root=True):
    270    def _simplify_connectors(expression, left, right):
    271        if left == right:
    272            if isinstance(expression, exp.Xor):
    273                return exp.false()
    274            return left
    275        if isinstance(expression, exp.And):
    276            if is_false(left) or is_false(right):
    277                return exp.false()
    278            if is_null(left) or is_null(right):
    279                return exp.null()
    280            if always_true(left) and always_true(right):
    281                return exp.true()
    282            if always_true(left):
    283                return right
    284            if always_true(right):
    285                return left
    286            return _simplify_comparison(expression, left, right)
    287        elif isinstance(expression, exp.Or):
    288            if always_true(left) or always_true(right):
    289                return exp.true()
    290            if is_false(left) and is_false(right):
    291                return exp.false()
    292            if (
    293                (is_null(left) and is_null(right))
    294                or (is_null(left) and is_false(right))
    295                or (is_false(left) and is_null(right))
    296            ):
    297                return exp.null()
    298            if is_false(left):
    299                return right
    300            if is_false(right):
    301                return left
    302            return _simplify_comparison(expression, left, right, or_=True)
    303
    304    if isinstance(expression, exp.Connector):
    305        return _flat_simplify(expression, _simplify_connectors, root)
    306    return expression

LT_LTE = (<class 'sqlglot.expressions.LT'>, <class 'sqlglot.expressions.LTE'>)
GT_GTE = (<class 'sqlglot.expressions.GT'>, <class 'sqlglot.expressions.GTE'>)
COMPARISONS = (<class 'sqlglot.expressions.LT'>, <class 'sqlglot.expressions.LTE'>, <class 'sqlglot.expressions.GT'>, <class 'sqlglot.expressions.GTE'>, <class 'sqlglot.expressions.EQ'>, <class 'sqlglot.expressions.NEQ'>, <class 'sqlglot.expressions.Is'>)
INVERSE_COMPARISONS: Dict[Type[sqlglot.expressions.Expression], Type[sqlglot.expressions.Expression]] = {<class 'sqlglot.expressions.LT'>: <class 'sqlglot.expressions.GT'>, <class 'sqlglot.expressions.GT'>: <class 'sqlglot.expressions.LT'>, <class 'sqlglot.expressions.LTE'>: <class 'sqlglot.expressions.GTE'>, <class 'sqlglot.expressions.GTE'>: <class 'sqlglot.expressions.LTE'>}
NONDETERMINISTIC = (<class 'sqlglot.expressions.Rand'>, <class 'sqlglot.expressions.Randn'>)
AND_OR = (<class 'sqlglot.expressions.And'>, <class 'sqlglot.expressions.Or'>)
def remove_complements(expression, root=True): View Source

    393def remove_complements(expression, root=True):
    394    """
    395    Removing complements.
    396
    397    A AND NOT A -> FALSE
    398    A OR NOT A -> TRUE
    399    """
    400    if isinstance(expression, AND_OR) and (root or not expression.same_parent):
    401        ops = set(expression.flatten())
    402        for op in ops:
    403            if isinstance(op, exp.Not) and op.this in ops:
    404                return exp.false() if isinstance(expression, exp.And) else exp.true()
    405
    406    return expression

Removing complements.

A AND NOT A -> FALSE A OR NOT A -> TRUE

def uniq_sort(expression, root=True): View Source

    409def uniq_sort(expression, root=True):
    410    """
    411    Uniq and sort a connector.
    412
    413    C AND A AND B AND B -> A AND B AND C
    414    """
    415    if isinstance(expression, exp.Connector) and (root or not expression.same_parent):
    416        flattened = tuple(expression.flatten())
    417
    418        if isinstance(expression, exp.Xor):
    419            result_func = exp.xor
    420            # Do not deduplicate XOR as A XOR A != A if A == True
    421            deduped = None
    422            arr = tuple((gen(e), e) for e in flattened)
    423        else:
    424            result_func = exp.and_ if isinstance(expression, exp.And) else exp.or_
    425            deduped = {gen(e): e for e in flattened}
    426            arr = tuple(deduped.items())
    427
    428        # check if the operands are already sorted, if not sort them
    429        # A AND C AND B -> A AND B AND C
    430        for i, (sql, e) in enumerate(arr[1:]):
    431            if sql < arr[i][0]:
    432                expression = result_func(*(e for _, e in sorted(arr)), copy=False)
    433                break
    434        else:
    435            # we didn't have to sort but maybe we need to dedup
    436            if deduped and len(deduped) < len(flattened):
    437                expression = result_func(*deduped.values(), copy=False)
    438
    439    return expression

Uniq and sort a connector.

C AND A AND B AND B -> A AND B AND C

def absorb_and_eliminate(expression, root=True): View Source

    442def absorb_and_eliminate(expression, root=True):
    443    """
    444    absorption:
    445        A AND (A OR B) -> A
    446        A OR (A AND B) -> A
    447        A AND (NOT A OR B) -> A AND B
    448        A OR (NOT A AND B) -> A OR B
    449    elimination:
    450        (A AND B) OR (A AND NOT B) -> A
    451        (A OR B) AND (A OR NOT B) -> A
    452    """
    453    if isinstance(expression, AND_OR) and (root or not expression.same_parent):
    454        kind = exp.Or if isinstance(expression, exp.And) else exp.And
    455
    456        ops = tuple(expression.flatten())
    457
    458        # Initialize lookup tables:
    459        # Set of all operands, used to find complements for absorption.
    460        op_set = set()
    461        # Sub-operands, used to find subsets for absorption.
    462        subops = defaultdict(list)
    463        # Pairs of complements, used for elimination.
    464        pairs = defaultdict(list)
    465
    466        # Populate the lookup tables
    467        for op in ops:
    468            op_set.add(op)
    469
    470            if not isinstance(op, kind):
    471                # In cases like: A OR (A AND B)
    472                # Subop will be: ^
    473                subops[op].append({op})
    474                continue
    475
    476            # In cases like: (A AND B) OR (A AND B AND C)
    477            # Subops will be: ^     ^
    478            subset = set(op.flatten())
    479            for i in subset:
    480                subops[i].append(subset)
    481
    482            a, b = op.unnest_operands()
    483            if isinstance(a, exp.Not):
    484                pairs[frozenset((a.this, b))].append((op, b))
    485            if isinstance(b, exp.Not):
    486                pairs[frozenset((a, b.this))].append((op, a))
    487
    488        for op in ops:
    489            if not isinstance(op, kind):
    490                continue
    491
    492            a, b = op.unnest_operands()
    493
    494            # Absorb
    495            if isinstance(a, exp.Not) and a.this in op_set:
    496                a.replace(exp.true() if kind == exp.And else exp.false())
    497                continue
    498            if isinstance(b, exp.Not) and b.this in op_set:
    499                b.replace(exp.true() if kind == exp.And else exp.false())
    500                continue
    501            superset = set(op.flatten())
    502            if any(any(subset < superset for subset in subops[i]) for i in superset):
    503                op.replace(exp.false() if kind == exp.And else exp.true())
    504                continue
    505
    506            # Eliminate
    507            for other, complement in pairs[frozenset((a, b))]:
    508                op.replace(complement)
    509                other.replace(complement)
    510
    511    return expression

absorption: A AND (A OR B) -> A A OR (A AND B) -> A A AND (NOT A OR B) -> A AND B A OR (NOT A AND B) -> A OR B elimination: (A AND B) OR (A AND NOT B) -> A (A OR B) AND (A OR NOT B) -> A

def propagate_constants(expression, root=True): View Source

    514def propagate_constants(expression, root=True):
    515    """
    516    Propagate constants for conjunctions in DNF:
    517
    518    SELECT * FROM t WHERE a = b AND b = 5 becomes
    519    SELECT * FROM t WHERE a = 5 AND b = 5
    520
    521    Reference: https://www.sqlite.org/optoverview.html
    522    """
    523
    524    if (
    525        isinstance(expression, exp.And)
    526        and (root or not expression.same_parent)
    527        and sqlglot.optimizer.normalize.normalized(expression, dnf=True)
    528    ):
    529        constant_mapping = {}
    530        for expr in walk_in_scope(expression, prune=lambda node: isinstance(node, exp.If)):
    531            if isinstance(expr, exp.EQ):
    532                l, r = expr.left, expr.right
    533
    534                # TODO: create a helper that can be used to detect nested literal expressions such
    535                # as CAST(123456 AS BIGINT), since we usually want to treat those as literals too
    536                if isinstance(l, exp.Column) and isinstance(r, exp.Literal):
    537                    constant_mapping[l] = (id(l), r)
    538
    539        if constant_mapping:
    540            for column in find_all_in_scope(expression, exp.Column):
    541                parent = column.parent
    542                column_id, constant = constant_mapping.get(column) or (None, None)
    543                if (
    544                    column_id is not None
    545                    and id(column) != column_id
    546                    and not (isinstance(parent, exp.Is) and isinstance(parent.expression, exp.Null))
    547                ):
    548                    column.replace(constant.copy())
    549
    550    return expression

Propagate constants for conjunctions in DNF:

SELECT * FROM t WHERE a = b AND b = 5 becomes SELECT * FROM t WHERE a = 5 AND b = 5

Reference: https://www.sqlite.org/optoverview.html

INVERSE_DATE_OPS: Dict[Type[sqlglot.expressions.Expression], Type[sqlglot.expressions.Expression]] = {<class 'sqlglot.expressions.DateAdd'>: <class 'sqlglot.expressions.Sub'>, <class 'sqlglot.expressions.DateSub'>: <class 'sqlglot.expressions.Add'>, <class 'sqlglot.expressions.DatetimeAdd'>: <class 'sqlglot.expressions.Sub'>, <class 'sqlglot.expressions.DatetimeSub'>: <class 'sqlglot.expressions.Add'>}
INVERSE_OPS: Dict[Type[sqlglot.expressions.Expression], Type[sqlglot.expressions.Expression]] = {<class 'sqlglot.expressions.DateAdd'>: <class 'sqlglot.expressions.Sub'>, <class 'sqlglot.expressions.DateSub'>: <class 'sqlglot.expressions.Add'>, <class 'sqlglot.expressions.DatetimeAdd'>: <class 'sqlglot.expressions.Sub'>, <class 'sqlglot.expressions.DatetimeSub'>: <class 'sqlglot.expressions.Add'>, <class 'sqlglot.expressions.Add'>: <class 'sqlglot.expressions.Sub'>, <class 'sqlglot.expressions.Sub'>: <class 'sqlglot.expressions.Add'>}
def simplify_equality(expression, *args, **kwargs): View Source

    170        def wrapped(expression, *args, **kwargs):
    171            try:
    172                return func(expression, *args, **kwargs)
    173            except exceptions:
    174                return expression

###### Use the subtraction and addition properties of equality to simplify expressions:

> x + 1 = 3 becomes x = 2

There are two binary operations in the above expression: + and = Here's how we reference all the operands in the code below:

      l     r
    x + 1 = 3
    a   b

def simplify_literals(expression, root=True): View Source

    625def simplify_literals(expression, root=True):
    626    if isinstance(expression, exp.Binary) and not isinstance(expression, exp.Connector):
    627        return _flat_simplify(expression, _simplify_binary, root)
    628
    629    if isinstance(expression, exp.Neg) and isinstance(expression.this, exp.Neg):
    630        return expression.this.this
    631
    632    if type(expression) in INVERSE_DATE_OPS:
    633        return _simplify_binary(expression, expression.this, expression.interval()) or expression
    634
    635    return expression

NULL_OK = (<class 'sqlglot.expressions.NullSafeEQ'>, <class 'sqlglot.expressions.NullSafeNEQ'>, <class 'sqlglot.expressions.PropertyEQ'>)
def simplify_parens(expression): View Source

    736def simplify_parens(expression):
    737    if not isinstance(expression, exp.Paren):
    738        return expression
    739
    740    this = expression.this
    741    parent = expression.parent
    742    parent_is_predicate = isinstance(parent, exp.Predicate)
    743
    744    if (
    745        not isinstance(this, exp.Select)
    746        and not isinstance(parent, exp.SubqueryPredicate)
    747        and (
    748            not isinstance(parent, (exp.Condition, exp.Binary))
    749            or isinstance(parent, exp.Paren)
    750            or (
    751                not isinstance(this, exp.Binary)
    752                and not (isinstance(this, (exp.Not, exp.Is)) and parent_is_predicate)
    753            )
    754            or (isinstance(this, exp.Predicate) and not parent_is_predicate)
    755            or (isinstance(this, exp.Add) and isinstance(parent, exp.Add))
    756            or (isinstance(this, exp.Mul) and isinstance(parent, exp.Mul))
    757            or (isinstance(this, exp.Mul) and isinstance(parent, (exp.Add, exp.Sub)))
    758        )
    759    ):
    760        return this
    761    return expression

def simplify_coalesce(expression): View Source

    772def simplify_coalesce(expression):
    773    # COALESCE(x) -> x
    774    if (
    775        isinstance(expression, exp.Coalesce)
    776        and (not expression.expressions or _is_nonnull_constant(expression.this))
    777        # COALESCE is also used as a Spark partitioning hint
    778        and not isinstance(expression.parent, exp.Hint)
    779    ):
    780        return expression.this
    781
    782    if not isinstance(expression, COMPARISONS):
    783        return expression
    784
    785    if isinstance(expression.left, exp.Coalesce):
    786        coalesce = expression.left
    787        other = expression.right
    788    elif isinstance(expression.right, exp.Coalesce):
    789        coalesce = expression.right
    790        other = expression.left
    791    else:
    792        return expression
    793
    794    # This transformation is valid for non-constants,
    795    # but it really only does anything if they are both constants.
    796    if not _is_constant(other):
    797        return expression
    798
    799    # Find the first constant arg
    800    for arg_index, arg in enumerate(coalesce.expressions):
    801        if _is_constant(arg):
    802            break
    803    else:
    804        return expression
    805
    806    coalesce.set("expressions", coalesce.expressions[:arg_index])
    807
    808    # Remove the COALESCE function. This is an optimization, skipping a simplify iteration,
    809    # since we already remove COALESCE at the top of this function.
    810    coalesce = coalesce if coalesce.expressions else coalesce.this
    811
    812    # This expression is more complex than when we started, but it will get simplified further
    813    return exp.paren(
    814        exp.or_(
    815            exp.and_(
    816                coalesce.is_(exp.null()).not_(copy=False),
    817                expression.copy(),
    818                copy=False,
    819            ),
    820            exp.and_(
    821                coalesce.is_(exp.null()),
    822                type(expression)(this=arg.copy(), expression=other.copy()),
    823                copy=False,
    824            ),
    825            copy=False,
    826        )
    827    )

CONCATS = (<class 'sqlglot.expressions.Concat'>, <class 'sqlglot.expressions.DPipe'>)
def simplify_concat(expression): View Source

    833def simplify_concat(expression):
    834    """Reduces all groups that contain string literals by concatenating them."""
    835    if not isinstance(expression, CONCATS) or (
    836        # We can't reduce a CONCAT_WS call if we don't statically know the separator
    837        isinstance(expression, exp.ConcatWs) and not expression.expressions[0].is_string
    838    ):
    839        return expression
    840
    841    if isinstance(expression, exp.ConcatWs):
    842        sep_expr, *expressions = expression.expressions
    843        sep = sep_expr.name
    844        concat_type = exp.ConcatWs
    845        args = {}
    846    else:
    847        expressions = expression.expressions
    848        sep = ""
    849        concat_type = exp.Concat
    850        args = {
    851            "safe": expression.args.get("safe"),
    852            "coalesce": expression.args.get("coalesce"),
    853        }
    854
    855    new_args = []
    856    for is_string_group, group in itertools.groupby(
    857        expressions or expression.flatten(), lambda e: e.is_string
    858    ):
    859        if is_string_group:
    860            new_args.append(exp.Literal.string(sep.join(string.name for string in group)))
    861        else:
    862            new_args.extend(group)
    863
    864    if len(new_args) == 1 and new_args[0].is_string:
    865        return new_args[0]
    866
    867    if concat_type is exp.ConcatWs:
    868        new_args = [sep_expr] + new_args
    869    elif isinstance(expression, exp.DPipe):
    870        return reduce(lambda x, y: exp.DPipe(this=x, expression=y), new_args)
    871
    872    return concat_type(expressions=new_args, **args)

Reduces all groups that contain string literals by concatenating them.

def simplify_conditionals(expression): View Source

    875def simplify_conditionals(expression):
    876    """Simplifies expressions like IF, CASE if their condition is statically known."""
    877    if isinstance(expression, exp.Case):
    878        this = expression.this
    879        for case in expression.args["ifs"]:
    880            cond = case.this
    881            if this:
    882                # Convert CASE x WHEN matching_value ... to CASE WHEN x = matching_value ...
    883                cond = cond.replace(this.pop().eq(cond))
    884
    885            if always_true(cond):
    886                return case.args["true"]
    887
    888            if always_false(cond):
    889                case.pop()
    890                if not expression.args["ifs"]:
    891                    return expression.args.get("default") or exp.null()
    892    elif isinstance(expression, exp.If) and not isinstance(expression.parent, exp.Case):
    893        if always_true(expression.this):
    894            return expression.args["true"]
    895        if always_false(expression.this):
    896            return expression.args.get("false") or exp.null()
    897
    898    return expression

Simplifies expressions like IF, CASE if their condition is statically known.

def simplify_startswith( expression: sqlglot.expressions.Expression) -> sqlglot.expressions.Expression: View Source

    901def simplify_startswith(expression: exp.Expression) -> exp.Expression:
    902    """
    903    Reduces a prefix check to either TRUE or FALSE if both the string and the
    904    prefix are statically known.
    905
    906    Example:
    907        >>> from sqlglot import parse_one
    908        >>> simplify_startswith(parse_one("STARTSWITH('foo', 'f')")).sql()
    909        'TRUE'
    910    """
    911    if (
    912        isinstance(expression, exp.StartsWith)
    913        and expression.this.is_string
    914        and expression.expression.is_string
    915    ):
    916        return exp.convert(expression.name.startswith(expression.expression.name))
    917
    918    return expression

Reduces a prefix check to either TRUE or FALSE if both the string and the prefix are statically known.

###### Example:

>     >>> from sqlglot import parse_one
>     >>> simplify_startswith(parse_one("STARTSWITH('foo', 'f')")).sql()
>     'TRUE'

DateRange = typing.Tuple[datetime.date, datetime.date]
DATETRUNC_BINARY_COMPARISONS: Dict[Type[sqlglot.expressions.Expression], Callable[[sqlglot.expressions.Expression, datetime.date, str, sqlglot.dialects.dialect.Dialect, sqlglot.expressions.DataType], Optional[sqlglot.expressions.Expression]]] = {<class 'sqlglot.expressions.LT'>: <function <lambda>>, <class 'sqlglot.expressions.GT'>: <function <lambda>>, <class 'sqlglot.expressions.LTE'>: <function <lambda>>, <class 'sqlglot.expressions.GTE'>: <function <lambda>>, <class 'sqlglot.expressions.EQ'>: <function _datetrunc_eq>, <class 'sqlglot.expressions.NEQ'>: <function _datetrunc_neq>}
DATETRUNC_COMPARISONS = {<class 'sqlglot.expressions.NEQ'>, <class 'sqlglot.expressions.GTE'>, <class 'sqlglot.expressions.EQ'>, <class 'sqlglot.expressions.LTE'>, <class 'sqlglot.expressions.GT'>, <class 'sqlglot.expressions.LT'>, <class 'sqlglot.expressions.In'>}
DATETRUNCS = (<class 'sqlglot.expressions.DateTrunc'>, <class 'sqlglot.expressions.TimestampTrunc'>)
def simplify_datetrunc(expression, *args, **kwargs): View Source

    170        def wrapped(expression, *args, **kwargs):
    171            try:
    172                return func(expression, *args, **kwargs)
    173            except exceptions:
    174                return expression

Simplify expressions like `DATE_TRUNC('year', x) >= CAST('2021-01-01' AS DATE)`

def sort_comparison( expression: sqlglot.expressions.Expression) -> sqlglot.expressions.Expression: View Source

    1067def sort_comparison(expression: exp.Expression) -> exp.Expression:
    1068    if expression.__class__ in COMPLEMENT_COMPARISONS:
    1069        l, r = expression.this, expression.expression
    1070        l_column = isinstance(l, exp.Column)
    1071        r_column = isinstance(r, exp.Column)
    1072        l_const = _is_constant(l)
    1073        r_const = _is_constant(r)
    1074
    1075        if (l_column and not r_column) or (r_const and not l_const):
    1076            return expression
    1077        if (r_column and not l_column) or (l_const and not r_const) or (gen(l) > gen(r)):
    1078            return INVERSE_COMPARISONS.get(expression.__class__, expression.__class__)(
    1079                this=r, expression=l
    1080            )
    1081    return expression

JOINS = {('RIGHT', 'OUTER'), ('', 'INNER'), ('RIGHT', ''), ('', '')}
def remove_where_true(expression): View Source

    1095def remove_where_true(expression):
    1096    for where in expression.find_all(exp.Where):
    1097        if always_true(where.this):
    1098            where.pop()
    1099    for join in expression.find_all(exp.Join):
    1100        if (
    1101            always_true(join.args.get("on"))
    1102            and not join.args.get("using")
    1103            and not join.args.get("method")
    1104            and (join.side, join.kind) in JOINS
    1105        ):
    1106            join.args["on"].pop()
    1107            join.set("side", None)
    1108            join.set("kind", "CROSS")

def always_true(expression): View Source

    1111def always_true(expression):
    1112    return (isinstance(expression, exp.Boolean) and expression.this) or isinstance(
    1113        expression, exp.Literal
    1114    )

def always_false(expression): View Source

    1117def always_false(expression):
    1118    return is_false(expression) or is_null(expression)

def is_complement(a, b): View Source

    1121def is_complement(a, b):
    1122    return isinstance(b, exp.Not) and b.this == a

def is_false(a: sqlglot.expressions.Expression) -> bool: View Source

    1125def is_false(a: exp.Expression) -> bool:
    1126    return type(a) is exp.Boolean and not a.this

def is_null(a: sqlglot.expressions.Expression) -> bool: View Source

    1129def is_null(a: exp.Expression) -> bool:
    1130    return type(a) is exp.Null

def eval_boolean(expression, a, b): View Source

    1133def eval_boolean(expression, a, b):
    1134    if isinstance(expression, (exp.EQ, exp.Is)):
    1135        return boolean_literal(a == b)
    1136    if isinstance(expression, exp.NEQ):
    1137        return boolean_literal(a != b)
    1138    if isinstance(expression, exp.GT):
    1139        return boolean_literal(a > b)
    1140    if isinstance(expression, exp.GTE):
    1141        return boolean_literal(a >= b)
    1142    if isinstance(expression, exp.LT):
    1143        return boolean_literal(a < b)
    1144    if isinstance(expression, exp.LTE):
    1145        return boolean_literal(a <= b)
    1146    return None

def cast_as_date(value: Any) -> Optional[datetime.date]: View Source

    1149def cast_as_date(value: t.Any) -> t.Optional[datetime.date]:
    1150    if isinstance(value, datetime.datetime):
    1151        return value.date()
    1152    if isinstance(value, datetime.date):
    1153        return value
    1154    try:
    1155        return datetime.datetime.fromisoformat(value).date()
    1156    except ValueError:
    1157        return None

def cast_as_datetime(value: Any) -> Optional[datetime.datetime]: View Source

    1160def cast_as_datetime(value: t.Any) -> t.Optional[datetime.datetime]:
    1161    if isinstance(value, datetime.datetime):
    1162        return value
    1163    if isinstance(value, datetime.date):
    1164        return datetime.datetime(year=value.year, month=value.month, day=value.day)
    1165    try:
    1166        return datetime.datetime.fromisoformat(value)
    1167    except ValueError:
    1168        return None

def cast_value(value: Any, to: sqlglot.expressions.DataType) -> Optional[datetime.date]: View Source

    1171def cast_value(value: t.Any, to: exp.DataType) -> t.Optional[t.Union[datetime.date, datetime.date]]:
    1172    if not value:
    1173        return None
    1174    if to.is_type(exp.DataType.Type.DATE):
    1175        return cast_as_date(value)
    1176    if to.is_type(*exp.DataType.TEMPORAL_TYPES):
    1177        return cast_as_datetime(value)
    1178    return None

def extract_date(cast: sqlglot.expressions.Expression) -> Optional[datetime.date]: View Source

    1181def extract_date(cast: exp.Expression) -> t.Optional[t.Union[datetime.date, datetime.date]]:
    1182    if isinstance(cast, exp.Cast):
    1183        to = cast.to
    1184    elif isinstance(cast, exp.TsOrDsToDate) and not cast.args.get("format"):
    1185        to = exp.DataType.build(exp.DataType.Type.DATE)
    1186    else:
    1187        return None
    1188
    1189    if isinstance(cast.this, exp.Literal):
    1190        value: t.Any = cast.this.name
    1191    elif isinstance(cast.this, (exp.Cast, exp.TsOrDsToDate)):
    1192        value = extract_date(cast.this)
    1193    else:
    1194        return None
    1195    return cast_value(value, to)

def extract_interval(expression): View Source

    1202def extract_interval(expression):
    1203    try:
    1204        n = int(expression.this.to_py())
    1205        unit = expression.text("unit").lower()
    1206        return interval(unit, n)
    1207    except (UnsupportedUnit, ModuleNotFoundError, ValueError):
    1208        return None

def extract_type(*expressions): View Source

    1211def extract_type(*expressions):
    1212    target_type = None
    1213    for expression in expressions:
    1214        target_type = expression.to if isinstance(expression, exp.Cast) else expression.type
    1215        if target_type:
    1216            break
    1217
    1218    return target_type

def date_literal(date, target_type=None): View Source

    1221def date_literal(date, target_type=None):
    1222    if not target_type or not target_type.is_type(*exp.DataType.TEMPORAL_TYPES):
    1223        target_type = (
    1224            exp.DataType.Type.DATETIME
    1225            if isinstance(date, datetime.datetime)
    1226            else exp.DataType.Type.DATE
    1227        )
    1228
    1229    return exp.cast(exp.Literal.string(date), target_type)

def interval(unit: str, n: int = 1): View Source

    1232def interval(unit: str, n: int = 1):
    1233    from dateutil.relativedelta import relativedelta
    1234
    1235    if unit == "year":
    1236        return relativedelta(years=1 * n)
    1237    if unit == "quarter":
    1238        return relativedelta(months=3 * n)
    1239    if unit == "month":
    1240        return relativedelta(months=1 * n)
    1241    if unit == "week":
    1242        return relativedelta(weeks=1 * n)
    1243    if unit == "day":
    1244        return relativedelta(days=1 * n)
    1245    if unit == "hour":
    1246        return relativedelta(hours=1 * n)
    1247    if unit == "minute":
    1248        return relativedelta(minutes=1 * n)
    1249    if unit == "second":
    1250        return relativedelta(seconds=1 * n)
    1251
    1252    raise UnsupportedUnit(f"Unsupported unit: {unit}")

def date_floor( d: datetime.date, unit: str, dialect: sqlglot.dialects.dialect.Dialect) -> datetime.date: View Source

    1255def date_floor(d: datetime.date, unit: str, dialect: Dialect) -> datetime.date:
    1256    if unit == "year":
    1257        return d.replace(month=1, day=1)
    1258    if unit == "quarter":
    1259        if d.month <= 3:
    1260            return d.replace(month=1, day=1)
    1261        elif d.month <= 6:
    1262            return d.replace(month=4, day=1)
    1263        elif d.month <= 9:
    1264            return d.replace(month=7, day=1)
    1265        else:
    1266            return d.replace(month=10, day=1)
    1267    if unit == "month":
    1268        return d.replace(month=d.month, day=1)
    1269    if unit == "week":
    1270        # Assuming week starts on Monday (0) and ends on Sunday (6)
    1271        return d - datetime.timedelta(days=d.weekday() - dialect.WEEK_OFFSET)
    1272    if unit == "day":
    1273        return d
    1274
    1275    raise UnsupportedUnit(f"Unsupported unit: {unit}")

def date_ceil( d: datetime.date, unit: str, dialect: sqlglot.dialects.dialect.Dialect) -> datetime.date: View Source

    1278def date_ceil(d: datetime.date, unit: str, dialect: Dialect) -> datetime.date:
    1279    floor = date_floor(d, unit, dialect)
    1280
    1281    if floor == d:
    1282        return d
    1283
    1284    return floor + interval(unit)

def boolean_literal(condition): View Source

    1287def boolean_literal(condition):
    1288    return exp.true() if condition else exp.false()

def gen(expression: Any) -> str: View Source

    1317def gen(expression: t.Any) -> str:
    1318    """Simple pseudo sql generator for quickly generating sortable and uniq strings.
    1319
    1320    Sorting and deduping sql is a necessary step for optimization. Calling the actual
    1321    generator is expensive so we have a bare minimum sql generator here.
    1322    """
    1323    return Gen().gen(expression)

Simple pseudo sql generator for quickly generating sortable and uniq strings.

Sorting and deduping sql is a necessary step for optimization. Calling the actual generator is expensive so we have a bare minimum sql generator here.

class Gen: View Source

    1326class Gen:
    1327    def __init__(self):
    1328        self.stack = []
    1329        self.sqls = []
    1330
    1331    def gen(self, expression: exp.Expression) -> str:
    1332        self.stack = [expression]
    1333        self.sqls.clear()
    1334
    1335        while self.stack:
    1336            node = self.stack.pop()
    1337
    1338            if isinstance(node, exp.Expression):
    1339                exp_handler_name = f"{node.key}_sql"
    1340
    1341                if hasattr(self, exp_handler_name):
    1342                    getattr(self, exp_handler_name)(node)
    1343                elif isinstance(node, exp.Func):
    1344                    self._function(node)
    1345                else:
    1346                    key = node.key.upper()
    1347                    self.stack.append(f"{key} " if self._args(node) else key)
    1348            elif type(node) is list:
    1349                for n in reversed(node):
    1350                    if n is not None:
    1351                        self.stack.extend((n, ","))
    1352                if node:
    1353                    self.stack.pop()
    1354            else:
    1355                if node is not None:
    1356                    self.sqls.append(str(node))
    1357
    1358        return "".join(self.sqls)
    1359
    1360    def add_sql(self, e: exp.Add) -> None:
    1361        self._binary(e, " + ")
    1362
    1363    def alias_sql(self, e: exp.Alias) -> None:
    1364        self.stack.extend(
    1365            (
    1366                e.args.get("alias"),
    1367                " AS ",
    1368                e.args.get("this"),
    1369            )
    1370        )
    1371
    1372    def and_sql(self, e: exp.And) -> None:
    1373        self._binary(e, " AND ")
    1374
    1375    def anonymous_sql(self, e: exp.Anonymous) -> None:
    1376        this = e.this
    1377        if isinstance(this, str):
    1378            name = this.upper()
    1379        elif isinstance(this, exp.Identifier):
    1380            name = this.this
    1381            name = f'"{name}"' if this.quoted else name.upper()
    1382        else:
    1383            raise ValueError(
    1384                f"Anonymous.this expects a str or an Identifier, got '{this.__class__.__name__}'."
    1385            )
    1386
    1387        self.stack.extend(
    1388            (
    1389                ")",
    1390                e.expressions,
    1391                "(",
    1392                name,
    1393            )
    1394        )
    1395
    1396    def between_sql(self, e: exp.Between) -> None:
    1397        self.stack.extend(
    1398            (
    1399                e.args.get("high"),
    1400                " AND ",
    1401                e.args.get("low"),
    1402                " BETWEEN ",
    1403                e.this,
    1404            )
    1405        )
    1406
    1407    def boolean_sql(self, e: exp.Boolean) -> None:
    1408        self.stack.append("TRUE" if e.this else "FALSE")
    1409
    1410    def bracket_sql(self, e: exp.Bracket) -> None:
    1411        self.stack.extend(
    1412            (
    1413                "]",
    1414                e.expressions,
    1415                "[",
    1416                e.this,
    1417            )
    1418        )
    1419
    1420    def column_sql(self, e: exp.Column) -> None:
    1421        for p in reversed(e.parts):
    1422            self.stack.extend((p, "."))
    1423        self.stack.pop()
    1424
    1425    def datatype_sql(self, e: exp.DataType) -> None:
    1426        self._args(e, 1)
    1427        self.stack.append(f"{e.this.name} ")
    1428
    1429    def div_sql(self, e: exp.Div) -> None:
    1430        self._binary(e, " / ")
    1431
    1432    def dot_sql(self, e: exp.Dot) -> None:
    1433        self._binary(e, ".")
    1434
    1435    def eq_sql(self, e: exp.EQ) -> None:
    1436        self._binary(e, " = ")
    1437
    1438    def from_sql(self, e: exp.From) -> None:
    1439        self.stack.extend((e.this, "FROM "))
    1440
    1441    def gt_sql(self, e: exp.GT) -> None:
    1442        self._binary(e, " > ")
    1443
    1444    def gte_sql(self, e: exp.GTE) -> None:
    1445        self._binary(e, " >= ")
    1446
    1447    def identifier_sql(self, e: exp.Identifier) -> None:
    1448        self.stack.append(f'"{e.this}"' if e.quoted else e.this)
    1449
    1450    def ilike_sql(self, e: exp.ILike) -> None:
    1451        self._binary(e, " ILIKE ")
    1452
    1453    def in_sql(self, e: exp.In) -> None:
    1454        self.stack.append(")")
    1455        self._args(e, 1)
    1456        self.stack.extend(
    1457            (
    1458                "(",
    1459                " IN ",
    1460                e.this,
    1461            )
    1462        )
    1463
    1464    def intdiv_sql(self, e: exp.IntDiv) -> None:
    1465        self._binary(e, " DIV ")
    1466
    1467    def is_sql(self, e: exp.Is) -> None:
    1468        self._binary(e, " IS ")
    1469
    1470    def like_sql(self, e: exp.Like) -> None:
    1471        self._binary(e, " Like ")
    1472
    1473    def literal_sql(self, e: exp.Literal) -> None:
    1474        self.stack.append(f"'{e.this}'" if e.is_string else e.this)
    1475
    1476    def lt_sql(self, e: exp.LT) -> None:
    1477        self._binary(e, " < ")
    1478
    1479    def lte_sql(self, e: exp.LTE) -> None:
    1480        self._binary(e, " <= ")
    1481
    1482    def mod_sql(self, e: exp.Mod) -> None:
    1483        self._binary(e, " % ")
    1484
    1485    def mul_sql(self, e: exp.Mul) -> None:
    1486        self._binary(e, " * ")
    1487
    1488    def neg_sql(self, e: exp.Neg) -> None:
    1489        self._unary(e, "-")
    1490
    1491    def neq_sql(self, e: exp.NEQ) -> None:
    1492        self._binary(e, " <> ")
    1493
    1494    def not_sql(self, e: exp.Not) -> None:
    1495        self._unary(e, "NOT ")
    1496
    1497    def null_sql(self, e: exp.Null) -> None:
    1498        self.stack.append("NULL")
    1499
    1500    def or_sql(self, e: exp.Or) -> None:
    1501        self._binary(e, " OR ")
    1502
    1503    def paren_sql(self, e: exp.Paren) -> None:
    1504        self.stack.extend(
    1505            (
    1506                ")",
    1507                e.this,
    1508                "(",
    1509            )
    1510        )
    1511
    1512    def sub_sql(self, e: exp.Sub) -> None:
    1513        self._binary(e, " - ")
    1514
    1515    def subquery_sql(self, e: exp.Subquery) -> None:
    1516        self._args(e, 2)
    1517        alias = e.args.get("alias")
    1518        if alias:
    1519            self.stack.append(alias)
    1520        self.stack.extend((")", e.this, "("))
    1521
    1522    def table_sql(self, e: exp.Table) -> None:
    1523        self._args(e, 4)
    1524        alias = e.args.get("alias")
    1525        if alias:
    1526            self.stack.append(alias)
    1527        for p in reversed(e.parts):
    1528            self.stack.extend((p, "."))
    1529        self.stack.pop()
    1530
    1531    def tablealias_sql(self, e: exp.TableAlias) -> None:
    1532        columns = e.columns
    1533
    1534        if columns:
    1535            self.stack.extend((")", columns, "("))
    1536
    1537        self.stack.extend((e.this, " AS "))
    1538
    1539    def var_sql(self, e: exp.Var) -> None:
    1540        self.stack.append(e.this)
    1541
    1542    def _binary(self, e: exp.Binary, op: str) -> None:
    1543        self.stack.extend((e.expression, op, e.this))
    1544
    1545    def _unary(self, e: exp.Unary, op: str) -> None:
    1546        self.stack.extend((e.this, op))
    1547
    1548    def _function(self, e: exp.Func) -> None:
    1549        self.stack.extend(
    1550            (
    1551                ")",
    1552                list(e.args.values()),
    1553                "(",
    1554                e.sql_name(),
    1555            )
    1556        )
    1557
    1558    def _args(self, node: exp.Expression, arg_index: int = 0) -> bool:
    1559        kvs = []
    1560        arg_types = list(node.arg_types)[arg_index:] if arg_index else node.arg_types
    1561
    1562        for k in arg_types or arg_types:
    1563            v = node.args.get(k)
    1564
    1565            if v is not None:
    1566                kvs.append([f":{k}", v])
    1567        if kvs:
    1568            self.stack.append(kvs)
    1569            return True
    1570        return False

stack
sqls
def gen(self, expression: sqlglot.expressions.Expression) -> str: View Source

    1331    def gen(self, expression: exp.Expression) -> str:
    1332        self.stack = [expression]
    1333        self.sqls.clear()
    1334
    1335        while self.stack:
    1336            node = self.stack.pop()
    1337
    1338            if isinstance(node, exp.Expression):
    1339                exp_handler_name = f"{node.key}_sql"
    1340
    1341                if hasattr(self, exp_handler_name):
    1342                    getattr(self, exp_handler_name)(node)
    1343                elif isinstance(node, exp.Func):
    1344                    self._function(node)
    1345                else:
    1346                    key = node.key.upper()
    1347                    self.stack.append(f"{key} " if self._args(node) else key)
    1348            elif type(node) is list:
    1349                for n in reversed(node):
    1350                    if n is not None:
    1351                        self.stack.extend((n, ","))
    1352                if node:
    1353                    self.stack.pop()
    1354            else:
    1355                if node is not None:
    1356                    self.sqls.append(str(node))
    1357
    1358        return "".join(self.sqls)

def add_sql(self, e: sqlglot.expressions.Add) -> None: View Source

    1360    def add_sql(self, e: exp.Add) -> None:
    1361        self._binary(e, " + ")

def alias_sql(self, e: sqlglot.expressions.Alias) -> None: View Source

    1363    def alias_sql(self, e: exp.Alias) -> None:
    1364        self.stack.extend(
    1365            (
    1366                e.args.get("alias"),
    1367                " AS ",
    1368                e.args.get("this"),
    1369            )
    1370        )

def and_sql(self, e: sqlglot.expressions.And) -> None: View Source

    1372    def and_sql(self, e: exp.And) -> None:
    1373        self._binary(e, " AND ")

def anonymous_sql(self, e: sqlglot.expressions.Anonymous) -> None: View Source

    1375    def anonymous_sql(self, e: exp.Anonymous) -> None:
    1376        this = e.this
    1377        if isinstance(this, str):
    1378            name = this.upper()
    1379        elif isinstance(this, exp.Identifier):
    1380            name = this.this
    1381            name = f'"{name}"' if this.quoted else name.upper()
    1382        else:
    1383            raise ValueError(
    1384                f"Anonymous.this expects a str or an Identifier, got '{this.__class__.__name__}'."
    1385            )
    1386
    1387        self.stack.extend(
    1388            (
    1389                ")",
    1390                e.expressions,
    1391                "(",
    1392                name,
    1393            )
    1394        )

def between_sql(self, e: sqlglot.expressions.Between) -> None: View Source

    1396    def between_sql(self, e: exp.Between) -> None:
    1397        self.stack.extend(
    1398            (
    1399                e.args.get("high"),
    1400                " AND ",
    1401                e.args.get("low"),
    1402                " BETWEEN ",
    1403                e.this,
    1404            )
    1405        )

def boolean_sql(self, e: sqlglot.expressions.Boolean) -> None: View Source

    1407    def boolean_sql(self, e: exp.Boolean) -> None:
    1408        self.stack.append("TRUE" if e.this else "FALSE")

def bracket_sql(self, e: sqlglot.expressions.Bracket) -> None: View Source

    1410    def bracket_sql(self, e: exp.Bracket) -> None:
    1411        self.stack.extend(
    1412            (
    1413                "]",
    1414                e.expressions,
    1415                "[",
    1416                e.this,
    1417            )
    1418        )

def column_sql(self, e: sqlglot.expressions.Column) -> None: View Source

    1420    def column_sql(self, e: exp.Column) -> None:
    1421        for p in reversed(e.parts):
    1422            self.stack.extend((p, "."))
    1423        self.stack.pop()

def datatype_sql(self, e: sqlglot.expressions.DataType) -> None: View Source

    1425    def datatype_sql(self, e: exp.DataType) -> None:
    1426        self._args(e, 1)
    1427        self.stack.append(f"{e.this.name} ")

def div_sql(self, e: sqlglot.expressions.Div) -> None: View Source

    1429    def div_sql(self, e: exp.Div) -> None:
    1430        self._binary(e, " / ")

def dot_sql(self, e: sqlglot.expressions.Dot) -> None: View Source

    1432    def dot_sql(self, e: exp.Dot) -> None:
    1433        self._binary(e, ".")

def eq_sql(self, e: sqlglot.expressions.EQ) -> None: View Source

    1435    def eq_sql(self, e: exp.EQ) -> None:
    1436        self._binary(e, " = ")

def from_sql(self, e: sqlglot.expressions.From) -> None: View Source

    1438    def from_sql(self, e: exp.From) -> None:
    1439        self.stack.extend((e.this, "FROM "))

def gt_sql(self, e: sqlglot.expressions.GT) -> None: View Source

    1441    def gt_sql(self, e: exp.GT) -> None:
    1442        self._binary(e, " > ")

def gte_sql(self, e: sqlglot.expressions.GTE) -> None: View Source

    1444    def gte_sql(self, e: exp.GTE) -> None:
    1445        self._binary(e, " >= ")

def identifier_sql(self, e: sqlglot.expressions.Identifier) -> None: View Source

    1447    def identifier_sql(self, e: exp.Identifier) -> None:
    1448        self.stack.append(f'"{e.this}"' if e.quoted else e.this)

def ilike_sql(self, e: sqlglot.expressions.ILike) -> None: View Source

    1450    def ilike_sql(self, e: exp.ILike) -> None:
    1451        self._binary(e, " ILIKE ")

def in_sql(self, e: sqlglot.expressions.In) -> None: View Source

    1453    def in_sql(self, e: exp.In) -> None:
    1454        self.stack.append(")")
    1455        self._args(e, 1)
    1456        self.stack.extend(
    1457            (
    1458                "(",
    1459                " IN ",
    1460                e.this,
    1461            )
    1462        )

def intdiv_sql(self, e: sqlglot.expressions.IntDiv) -> None: View Source

    1464    def intdiv_sql(self, e: exp.IntDiv) -> None:
    1465        self._binary(e, " DIV ")

def is_sql(self, e: sqlglot.expressions.Is) -> None: View Source

    1467    def is_sql(self, e: exp.Is) -> None:
    1468        self._binary(e, " IS ")

def like_sql(self, e: sqlglot.expressions.Like) -> None: View Source

    1470    def like_sql(self, e: exp.Like) -> None:
    1471        self._binary(e, " Like ")

def literal_sql(self, e: sqlglot.expressions.Literal) -> None: View Source

    1473    def literal_sql(self, e: exp.Literal) -> None:
    1474        self.stack.append(f"'{e.this}'" if e.is_string else e.this)

def lt_sql(self, e: sqlglot.expressions.LT) -> None: View Source

    1476    def lt_sql(self, e: exp.LT) -> None:
    1477        self._binary(e, " < ")

def lte_sql(self, e: sqlglot.expressions.LTE) -> None: View Source

    1479    def lte_sql(self, e: exp.LTE) -> None:
    1480        self._binary(e, " <= ")

def mod_sql(self, e: sqlglot.expressions.Mod) -> None: View Source

    1482    def mod_sql(self, e: exp.Mod) -> None:
    1483        self._binary(e, " % ")

def mul_sql(self, e: sqlglot.expressions.Mul) -> None: View Source

    1485    def mul_sql(self, e: exp.Mul) -> None:
    1486        self._binary(e, " * ")

def neg_sql(self, e: sqlglot.expressions.Neg) -> None: View Source

    1488    def neg_sql(self, e: exp.Neg) -> None:
    1489        self._unary(e, "-")

def neq_sql(self, e: sqlglot.expressions.NEQ) -> None: View Source

    1491    def neq_sql(self, e: exp.NEQ) -> None:
    1492        self._binary(e, " <> ")

def not_sql(self, e: sqlglot.expressions.Not) -> None: View Source

    1494    def not_sql(self, e: exp.Not) -> None:
    1495        self._unary(e, "NOT ")

def null_sql(self, e: sqlglot.expressions.Null) -> None: View Source

    1497    def null_sql(self, e: exp.Null) -> None:
    1498        self.stack.append("NULL")

def or_sql(self, e: sqlglot.expressions.Or) -> None: View Source

    1500    def or_sql(self, e: exp.Or) -> None:
    1501        self._binary(e, " OR ")

def paren_sql(self, e: sqlglot.expressions.Paren) -> None: View Source

    1503    def paren_sql(self, e: exp.Paren) -> None:
    1504        self.stack.extend(
    1505            (
    1506                ")",
    1507                e.this,
    1508                "(",
    1509            )
    1510        )

def sub_sql(self, e: sqlglot.expressions.Sub) -> None: View Source

    1512    def sub_sql(self, e: exp.Sub) -> None:
    1513        self._binary(e, " - ")

def subquery_sql(self, e: sqlglot.expressions.Subquery) -> None: View Source

    1515    def subquery_sql(self, e: exp.Subquery) -> None:
    1516        self._args(e, 2)
    1517        alias = e.args.get("alias")
    1518        if alias:
    1519            self.stack.append(alias)
    1520        self.stack.extend((")", e.this, "("))

def table_sql(self, e: sqlglot.expressions.Table) -> None: View Source

    1522    def table_sql(self, e: exp.Table) -> None:
    1523        self._args(e, 4)
    1524        alias = e.args.get("alias")
    1525        if alias:
    1526            self.stack.append(alias)
    1527        for p in reversed(e.parts):
    1528            self.stack.extend((p, "."))
    1529        self.stack.pop()

def tablealias_sql(self, e: sqlglot.expressions.TableAlias) -> None: View Source

    1531    def tablealias_sql(self, e: exp.TableAlias) -> None:
    1532        columns = e.columns
    1533
    1534        if columns:
    1535            self.stack.extend((")", columns, "("))
    1536
    1537        self.stack.extend((e.this, " AS "))

def var_sql(self, e: sqlglot.expressions.Var) -> None: View Source

    1539    def var_sql(self, e: exp.Var) -> None:
    1540        self.stack.append(e.this)