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fix: correct if_then and switch_expression type inference calls #128

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Merged
nielspardon merged 3 commits into from
Dec 8, 2025
Merged

fix: correct if_then and switch_expression type inference calls #128

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6422d2a
fix: if_then and switch_expresion calling o infer_expression_type
giospada Nov 21, 2025
f6e7730
fix: added parameter parent_schema to infer_nested_type
giospada Dec 5, 2025
8844534
feat: added some test for infer_expression_type
giospada Dec 5, 2025
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25 changes: 16 additions & 9 deletions src/substrait/type_inference.py
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
import substrait.gen.proto.algebra_pb2 as stalg
import substrait.gen.proto.extended_expression_pb2 as stee
import substrait.gen.proto.type_pb2 as stt
import substrait.gen.proto.plan_pb2 as stp
import substrait.gen.proto.type_pb2 as stt


def infer_literal_type(literal: stalg.Expression.Literal) -> stt.Type:
Expand Down Expand Up @@ -127,7 +127,7 @@ def infer_literal_type(literal: stalg.Expression.Literal) -> stt.Type:
raise Exception(f"Unknown literal_type {literal_type}")


def infer_nested_type(nested: stalg.Expression.Nested) -> stt.Type:
def infer_nested_type(nested: stalg.Expression.Nested, parent_schema) -> stt.Type:
nested_type = nested.WhichOneof("nested_type")

nullability = (
Expand All @@ -139,22 +139,27 @@ def infer_nested_type(nested: stalg.Expression.Nested) -> stt.Type:
if nested_type == "struct":
return stt.Type(
struct=stt.Type.Struct(
types=[infer_expression_type(f) for f in nested.struct.fields],
types=[
infer_expression_type(f, parent_schema)
for f in nested.struct.fields
],
nullability=nullability,
)
)
elif nested_type == "list":
return stt.Type(
list=stt.Type.List(
type=infer_expression_type(nested.list.values[0]),
type=infer_expression_type(nested.list.values[0], parent_schema),
nullability=nullability,
)
)
elif nested_type == "map":
return stt.Type(
map=stt.Type.Map(
key=infer_expression_type(nested.map.key_values[0].key),
value=infer_expression_type(nested.map.key_values[0].value),
key=infer_expression_type(nested.map.key_values[0].key, parent_schema),
value=infer_expression_type(
nested.map.key_values[0].value, parent_schema
),
nullability=nullability,
)
)
Expand Down Expand Up @@ -191,17 +196,19 @@ def infer_expression_type(
elif rex_type == "window_function":
return expression.window_function.output_type
elif rex_type == "if_then":
return infer_expression_type(expression.if_then.ifs[0].then)
return infer_expression_type(expression.if_then.ifs[0].then, parent_schema)
elif rex_type == "switch_expression":
return infer_expression_type(expression.switch_expression.ifs[0].then)
return infer_expression_type(
expression.switch_expression.ifs[0].then, parent_schema
)
elif rex_type == "cast":
return expression.cast.type
elif rex_type == "singular_or_list" or rex_type == "multi_or_list":
return stt.Type(
bool=stt.Type.Boolean(nullability=stt.Type.Nullability.NULLABILITY_NULLABLE)
)
elif rex_type == "nested":
return infer_nested_type(expression.nested)
return infer_nested_type(expression.nested, parent_schema)
elif rex_type == "subquery":
subquery_type = expression.subquery.WhichOneof("subquery_type")

Expand Down
150 changes: 148 additions & 2 deletions tests/test_type_inference.py
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Original file line number Diff line number Diff line change
@@ -1,7 +1,10 @@
import substrait.gen.proto.algebra_pb2 as stalg
import substrait.gen.proto.type_pb2 as stt
from substrait.type_inference import infer_rel_schema

from substrait.type_inference import (
infer_expression_type,
infer_nested_type,
infer_rel_schema,
)

struct = stt.Type.Struct(
types=[
Expand Down Expand Up @@ -312,3 +315,146 @@ def test_inference_join_left_mark():
)

assert infer_rel_schema(rel) == expected


def test_infer_expression_type_literal():
"""Test infer_expression_type with a literal expression."""
expr = stalg.Expression(literal=stalg.Expression.Literal(i64=42, nullable=False))

result = infer_expression_type(expr, struct)

expected = stt.Type(i64=stt.Type.I64(nullability=stt.Type.NULLABILITY_REQUIRED))
assert result == expected


def test_infer_expression_type_selection():
"""Test infer_expression_type with a field selection expression."""
expr = stalg.Expression(
selection=stalg.Expression.FieldReference(
root_reference=stalg.Expression.FieldReference.RootReference(),
direct_reference=stalg.Expression.ReferenceSegment(
struct_field=stalg.Expression.ReferenceSegment.StructField(field=0),
),
)
)

result = infer_expression_type(expr, struct)

# Should return the type of field 0 from the struct (i64)
expected = stt.Type(i64=stt.Type.I64(nullability=stt.Type.NULLABILITY_REQUIRED))
assert result == expected


def test_infer_expression_type_window_function():
"""Test infer_expression_type with a window function expression."""
expr = stalg.Expression(
window_function=stalg.Expression.WindowFunction(
function_reference=0,
output_type=stt.Type(
i64=stt.Type.I64(nullability=stt.Type.NULLABILITY_NULLABLE)
),
)
)

result = infer_expression_type(expr, struct)

expected = stt.Type(i64=stt.Type.I64(nullability=stt.Type.NULLABILITY_NULLABLE))
assert result == expected


def test_infer_nested_type_struct():
"""Test infer_nested_type with a struct nested expression."""
expr = stalg.Expression(
nested=stalg.Expression.Nested(
struct=stalg.Expression.Nested.Struct(
fields=[
stalg.Expression(
literal=stalg.Expression.Literal(i32=1, nullable=False)
),
stalg.Expression(
literal=stalg.Expression.Literal(string="test", nullable=True)
),
]
),
nullable=False,
)
)

result = infer_nested_type(expr.nested, struct)

expected = stt.Type(
struct=stt.Type.Struct(
types=[
stt.Type(i32=stt.Type.I32(nullability=stt.Type.NULLABILITY_REQUIRED)),
stt.Type(
string=stt.Type.String(nullability=stt.Type.NULLABILITY_NULLABLE)
),
],
nullability=stt.Type.NULLABILITY_REQUIRED,
)
)
assert result == expected


def test_infer_nested_type_list():
"""Test infer_nested_type with a list nested expression."""
expr = stalg.Expression(
nested=stalg.Expression.Nested(
list=stalg.Expression.Nested.List(
values=[
stalg.Expression(
literal=stalg.Expression.Literal(fp32=3.14, nullable=False)
),
]
),
nullable=False,
)
)

result = infer_nested_type(expr.nested, struct)

expected = stt.Type(
list=stt.Type.List(
type=stt.Type(
fp32=stt.Type.FP32(nullability=stt.Type.NULLABILITY_REQUIRED)
),
nullability=stt.Type.NULLABILITY_REQUIRED,
)
)
assert result == expected


def test_infer_nested_type_map():
"""Test infer_nested_type with a map nested expression."""
expr = stalg.Expression(
nested=stalg.Expression.Nested(
map=stalg.Expression.Nested.Map(
key_values=[
stalg.Expression.Nested.Map.KeyValue(
key=stalg.Expression(
literal=stalg.Expression.Literal(
string="key", nullable=False
)
),
value=stalg.Expression(
literal=stalg.Expression.Literal(i32=42, nullable=False)
),
),
]
),
nullable=False,
)
)

result = infer_nested_type(expr.nested, struct)

expected = stt.Type(
map=stt.Type.Map(
key=stt.Type(
string=stt.Type.String(nullability=stt.Type.NULLABILITY_REQUIRED)
),
value=stt.Type(i32=stt.Type.I32(nullability=stt.Type.NULLABILITY_REQUIRED)),
nullability=stt.Type.NULLABILITY_REQUIRED,
)
)
assert result == expected