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sqlglot.optimizer.canonicalize

  1from __future__ import annotations
  2
  3import itertools
  4
  5from sqlglot import exp
  6
  7
  8def canonicalize(expression: exp.Expression) -> exp.Expression:
  9    """Converts a sql expression into a standard form.
 10
 11    This method relies on annotate_types because many of the
 12    conversions rely on type inference.
 13
 14    Args:
 15        expression: The expression to canonicalize.
 16    """
 17    exp.replace_children(expression, canonicalize)
 18
 19    expression = add_text_to_concat(expression)
 20    expression = replace_date_funcs(expression)
 21    expression = coerce_type(expression)
 22    expression = remove_redundant_casts(expression)
 23    expression = ensure_bool_predicates(expression)
 24    expression = remove_ascending_order(expression)
 25
 26    return expression
 27
 28
 29def add_text_to_concat(node: exp.Expression) -> exp.Expression:
 30    if isinstance(node, exp.Add) and node.type and node.type.this in exp.DataType.TEXT_TYPES:
 31        node = exp.Concat(expressions=[node.left, node.right])
 32    return node
 33
 34
 35def replace_date_funcs(node: exp.Expression) -> exp.Expression:
 36    if isinstance(node, exp.Date) and not node.expressions and not node.args.get("zone"):
 37        return exp.cast(node.this, to=exp.DataType.Type.DATE)
 38    if isinstance(node, exp.Timestamp) and not node.expression:
 39        return exp.cast(node.this, to=exp.DataType.Type.TIMESTAMP)
 40    return node
 41
 42
 43def coerce_type(node: exp.Expression) -> exp.Expression:
 44    if isinstance(node, exp.Binary):
 45        _coerce_date(node.left, node.right)
 46    elif isinstance(node, exp.Between):
 47        _coerce_date(node.this, node.args["low"])
 48    elif isinstance(node, exp.Extract):
 49        if node.expression.type.this not in exp.DataType.TEMPORAL_TYPES:
 50            _replace_cast(node.expression, "datetime")
 51    return node
 52
 53
 54def remove_redundant_casts(expression: exp.Expression) -> exp.Expression:
 55    if (
 56        isinstance(expression, exp.Cast)
 57        and expression.to.type
 58        and expression.this.type
 59        and expression.to.type.this == expression.this.type.this
 60    ):
 61        return expression.this
 62    return expression
 63
 64
 65def ensure_bool_predicates(expression: exp.Expression) -> exp.Expression:
 66    if isinstance(expression, exp.Connector):
 67        _replace_int_predicate(expression.left)
 68        _replace_int_predicate(expression.right)
 69
 70    elif isinstance(expression, (exp.Where, exp.Having)):
 71        _replace_int_predicate(expression.this)
 72
 73    return expression
 74
 75
 76def remove_ascending_order(expression: exp.Expression) -> exp.Expression:
 77    if isinstance(expression, exp.Ordered) and expression.args.get("desc") is False:
 78        # Convert ORDER BY a ASC to ORDER BY a
 79        expression.set("desc", None)
 80
 81    return expression
 82
 83
 84def _coerce_date(a: exp.Expression, b: exp.Expression) -> None:
 85    for a, b in itertools.permutations([a, b]):
 86        if (
 87            a.type
 88            and a.type.this == exp.DataType.Type.DATE
 89            and b.type
 90            and b.type.this not in (exp.DataType.Type.DATE, exp.DataType.Type.INTERVAL)
 91        ):
 92            _replace_cast(b, "date")
 93
 94
 95def _replace_cast(node: exp.Expression, to: str) -> None:
 96    node.replace(exp.cast(node.copy(), to=to))
 97
 98
 99def _replace_int_predicate(expression: exp.Expression) -> None:
100    if expression.type and expression.type.this in exp.DataType.INTEGER_TYPES:
101        expression.replace(exp.NEQ(this=expression.copy(), expression=exp.Literal.number(0)))
def canonicalize( expression: sqlglot.expressions.Expression) -> sqlglot.expressions.Expression:
 9def canonicalize(expression: exp.Expression) -> exp.Expression:
10    """Converts a sql expression into a standard form.
11
12    This method relies on annotate_types because many of the
13    conversions rely on type inference.
14
15    Args:
16        expression: The expression to canonicalize.
17    """
18    exp.replace_children(expression, canonicalize)
19
20    expression = add_text_to_concat(expression)
21    expression = replace_date_funcs(expression)
22    expression = coerce_type(expression)
23    expression = remove_redundant_casts(expression)
24    expression = ensure_bool_predicates(expression)
25    expression = remove_ascending_order(expression)
26
27    return expression

Converts a sql expression into a standard form.

This method relies on annotate_types because many of the conversions rely on type inference.

Arguments:
  • expression: The expression to canonicalize.
def add_text_to_concat(node: sqlglot.expressions.Expression) -> sqlglot.expressions.Expression:
30def add_text_to_concat(node: exp.Expression) -> exp.Expression:
31    if isinstance(node, exp.Add) and node.type and node.type.this in exp.DataType.TEXT_TYPES:
32        node = exp.Concat(expressions=[node.left, node.right])
33    return node
def replace_date_funcs(node: sqlglot.expressions.Expression) -> sqlglot.expressions.Expression:
36def replace_date_funcs(node: exp.Expression) -> exp.Expression:
37    if isinstance(node, exp.Date) and not node.expressions and not node.args.get("zone"):
38        return exp.cast(node.this, to=exp.DataType.Type.DATE)
39    if isinstance(node, exp.Timestamp) and not node.expression:
40        return exp.cast(node.this, to=exp.DataType.Type.TIMESTAMP)
41    return node
def coerce_type(node: sqlglot.expressions.Expression) -> sqlglot.expressions.Expression:
44def coerce_type(node: exp.Expression) -> exp.Expression:
45    if isinstance(node, exp.Binary):
46        _coerce_date(node.left, node.right)
47    elif isinstance(node, exp.Between):
48        _coerce_date(node.this, node.args["low"])
49    elif isinstance(node, exp.Extract):
50        if node.expression.type.this not in exp.DataType.TEMPORAL_TYPES:
51            _replace_cast(node.expression, "datetime")
52    return node
def remove_redundant_casts( expression: sqlglot.expressions.Expression) -> sqlglot.expressions.Expression:
55def remove_redundant_casts(expression: exp.Expression) -> exp.Expression:
56    if (
57        isinstance(expression, exp.Cast)
58        and expression.to.type
59        and expression.this.type
60        and expression.to.type.this == expression.this.type.this
61    ):
62        return expression.this
63    return expression
def ensure_bool_predicates( expression: sqlglot.expressions.Expression) -> sqlglot.expressions.Expression:
66def ensure_bool_predicates(expression: exp.Expression) -> exp.Expression:
67    if isinstance(expression, exp.Connector):
68        _replace_int_predicate(expression.left)
69        _replace_int_predicate(expression.right)
70
71    elif isinstance(expression, (exp.Where, exp.Having)):
72        _replace_int_predicate(expression.this)
73
74    return expression
def remove_ascending_order( expression: sqlglot.expressions.Expression) -> sqlglot.expressions.Expression:
77def remove_ascending_order(expression: exp.Expression) -> exp.Expression:
78    if isinstance(expression, exp.Ordered) and expression.args.get("desc") is False:
79        # Convert ORDER BY a ASC to ORDER BY a
80        expression.set("desc", None)
81
82    return expression