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Avoid recursing into already substituted expressions #836

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Merged
phofl merged 2 commits into from
Feb 2, 2024
Merged

Avoid recursing into already substituted expressions #836

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1642a04
Avoid recursing into already substituted expressions
fjetter Feb 2, 2024
bbddff7
move to private method
fjetter Feb 2, 2024
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10 changes: 8 additions & 2 deletions dask_expr/_core.py
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Original file line number Diff line number Diff line change
Expand Up @@ -461,7 +461,11 @@ def substitute(self, old, new) -> Expr:
>>> (df + 10).substitute(10, 20)
df + 20
"""
return self._substitute(old, new, _seen=set())

def _substitute(self, old, new, _seen):
if self._name in _seen:
return self
# Check if we are replacing a literal
if isinstance(old, Expr):
substitute_literal = False
Expand All @@ -476,7 +480,7 @@ def substitute(self, old, new) -> Expr:
update = False
for operand in self.operands:
if isinstance(operand, Expr):
val = operand.substitute(old, new)
val = operand._substitute(old, new, _seen)
if operand._name != val._name:
update = True
new_exprs.append(val)
Expand All @@ -491,7 +495,7 @@ def substitute(self, old, new) -> Expr:
# do so for the `Fused.exprs` operand.
val = []
for op in operand:
val.append(op.substitute(old, new))
val.append(op._substitute(old, new, _seen))
if val[-1]._name != op._name:
update = True
new_exprs.append(val)
Expand All @@ -508,6 +512,8 @@ def substitute(self, old, new) -> Expr:

if update: # Only recreate if something changed
return type(self)(*new_exprs)
else:
_seen.add(self._name)
return self

def substitute_parameters(self, substitutions: dict) -> Expr:
Expand Down