blob: 59f3fec9e0c401ac478c6358326965a3f1a6fa4e (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
|
from __future__ import annotations
import typing as t
from sqlglot import exp
def expand_laterals(expression: exp.Expression) -> exp.Expression:
"""
Expand lateral column alias references.
This assumes `qualify_columns` as already run.
Example:
>>> import sqlglot
>>> sql = "SELECT x.a + 1 AS b, b + 1 AS c FROM x"
>>> expression = sqlglot.parse_one(sql)
>>> expand_laterals(expression).sql()
'SELECT x.a + 1 AS b, x.a + 1 + 1 AS c FROM x'
Args:
expression: expression to optimize
Returns:
optimized expression
"""
for select in expression.find_all(exp.Select):
alias_to_expression: t.Dict[str, exp.Expression] = {}
for projection in select.expressions:
for column in projection.find_all(exp.Column):
if not column.table and column.name in alias_to_expression:
column.replace(alias_to_expression[column.name].copy())
if isinstance(projection, exp.Alias):
alias_to_expression[projection.alias] = projection.this
return expression
|
