Initial Import

pyproject.toml

@@ -5,7 +5,7 @@ authors = [{name = "Substrait contributors", email = "[email protected]
 license = {text = "Apache-2.0"}
 readme = "README.md"
 requires-python = ">=3.8.1"
-dependencies = ["protobuf >= 3.20"]
+dependencies = ["protobuf >= 3.20", "sqlglot >= 23.10.0"]
 dynamic = ["version"]
 
 [tool.setuptools_scm]

src/substrait/sql/__init__.py

@@ -0,0 +1 @@
+from .extended_expression import parse_sql_extended_expression

src/substrait/sql/extended_expression.py

@@ -0,0 +1,315 @@
+import pathlib
+
+import sqlglot
+import yaml
+
+from substrait import proto
+
+
+SQL_BINARY_FUNCTIONS = {
+    # Arithmetic
+    "add": "add",
+    "div": "div",
+    "mul": "mul",
+    "sub": "sub",
+    # Comparisons
+    "eq": "equal",
+}
+
+
+def parse_sql_extended_expression(catalog, schema, sql):
+    select = sqlglot.parse_one(sql)
+    if not isinstance(select, sqlglot.expressions.Select):
+        raise ValueError("a SELECT statement was expected")
+
+    invoked_functions_projection, projections = _substrait_projection_from_sqlglot(
+        catalog, schema, select.expressions
+    )
+    extension_uris, extensions = catalog.extensions_for_functions(
+        invoked_functions_projection
+    )
+    projection_extended_expr = proto.ExtendedExpression(
+        extension_uris=extension_uris,
+        extensions=extensions,
+        base_schema=schema,
+        referred_expr=projections,
+    )
+
+    invoked_functions_filter, filter_expr = _substrait_expression_from_sqlglot(
+        catalog, schema, select.find(sqlglot.expressions.Where).this
+    )
+    extension_uris, extensions = catalog.extensions_for_functions(
+        invoked_functions_filter
+    )
+    filter_extended_expr = proto.ExtendedExpression(
+        extension_uris=extension_uris,
+        extensions=extensions,
+        base_schema=schema,
+        referred_expr=[proto.ExpressionReference(expression=filter_expr)],
+    )
+
+    return projection_extended_expr, filter_extended_expr
+
+
+def _substrait_projection_from_sqlglot(catalog, schema, expressions):
+    if not expressions:
+        return set(), []
+
+    # My understanding of ExtendedExpressions is that they are meant to directly
+    # point to the Expression that ProjectRel would contain, so we don't actually
+    # need a ProjectRel at all.
+    """
+    projection_sub = proto.ProjectRel(
+        input=proto.Rel(
+            read=proto.ReadRel(
+                named_table=proto.ReadRel.NamedTable(names=["__table__"]),
+                base_schema=schema,
+            )
+        ),
+        expressions=[],
+    )
+    """
+
+    substrait_expressions = []
+    invoked_functions = set()
+    for sqlexpr in expressions:
+        output_names = []
+        if isinstance(sqlexpr, sqlglot.expressions.Alias):
+            output_names = [sqlexpr.output_name]
+            sqlexpr = sqlexpr.this
+        _, substrait_expr = _parse_expression(
+            catalog, schema, sqlexpr, invoked_functions
+        )
+        substrait_expr_reference = proto.ExpressionReference(
+            expression=substrait_expr, output_names=output_names
+        )
+        substrait_expressions.append(substrait_expr_reference)
+
+    return invoked_functions, substrait_expressions
+
+
+def _substrait_expression_from_sqlglot(catalog, schema, sqlglot_node):
+    if not sqlglot_node:
+        return set(), None
+
+    invoked_functions = set()
+    _, substrait_expr = _parse_expression(
+        catalog, schema, sqlglot_node, invoked_functions
+    )
+    return invoked_functions, substrait_expr
+
+
+def _parse_expression(catalog, schema, expr, invoked_functions):
+    # TODO: Propagate up column names (output_names) so that the projections _always_ have an output_name
+    if isinstance(expr, sqlglot.expressions.Literal):
+        if expr.is_string:
+            return proto.Type(string=proto.Type.String()), proto.Expression(
+                literal=proto.Expression.Literal(string=expr.text)
+            )
+        elif expr.is_int:
+            return proto.Type(i32=proto.Type.I32()), proto.Expression(
+                literal=proto.Expression.Literal(i32=int(expr.name))
+            )
+        elif sqlglot.helper.is_float(expr.name):
+            return proto.Type(fp32=proto.Type.FP32()), proto.Expression(
+                literal=proto.Expression.Literal(float=float(expr.name))
+            )
+        else:
+            raise ValueError(f"Unsupporter literal: {expr.text}")
+    elif isinstance(expr, sqlglot.expressions.Column):
+        column_name = expr.output_name
+        schema_field = list(schema.names).index(column_name)
+        schema_type = schema.struct.types[schema_field]
+        return schema_type, proto.Expression(
+            selection=proto.Expression.FieldReference(
+                direct_reference=proto.Expression.ReferenceSegment(
+                    struct_field=proto.Expression.ReferenceSegment.StructField(
+                        field=schema_field
+                    )
+                )
+            )
+        )
+    elif expr.key in SQL_BINARY_FUNCTIONS:
+        left_type, left = _parse_expression(
+            catalog, schema, expr.left, invoked_functions
+        )
+        right_type, right = _parse_expression(
+            catalog, schema, expr.right, invoked_functions
+        )
+        function_name = SQL_BINARY_FUNCTIONS[expr.key]
+        signature, result_type, function_expression = _parse_function_invokation(
+            function_name, left_type, left, right_type, right
+        )
+        invoked_functions.add(signature)
+        return result_type, function_expression
+    else:
+        raise ValueError(
+            f"Unsupported expression in ExtendedExpression: '{expr.key}' -> {expr}"
+        )
+
+
+def _parse_function_invokation(function_name, left_type, left, right_type, right):
+    signature = f"{function_name}:{left_type.WhichOneof('kind')}_{right_type.WhichOneof('kind')}"
+    try:
+        function_anchor = catalog.function_anchor(signature)
+    except KeyError:
+        # not function found with the exact types, try any1_any1 version
+        signature = f"{function_name}:any1_any1"
+        function_anchor = catalog.function_anchor(signature)
+    return (
+        signature,
+        left_type,
+        proto.Expression(
+            scalar_function=proto.Expression.ScalarFunction(
+                function_reference=function_anchor,
+                arguments=[
+                    proto.FunctionArgument(value=left),
+                    proto.FunctionArgument(value=right),
+                ],
+            )
+        ),
+    )
+
+
+class FunctionsCatalog:
+    STANDARD_EXTENSIONS = (
+        "/functions_aggregate_approx.yaml",
+        "/functions_aggregate_generic.yaml",
+        "/functions_arithmetic.yaml",
+        "/functions_arithmetic_decimal.yaml",
+        "/functions_boolean.yaml",
+        "/functions_comparison.yaml",
+        "/functions_datetime.yaml",
+        "/functions_geometry.yaml",
+        "/functions_logarithmic.yaml",
+        "/functions_rounding.yaml",
+        "/functions_set.yaml",
+        "/functions_string.yaml",
+    )
+
+    def __init__(self):
+        self._declarations = {}
+        self._registered_extensions = {}
+        self._functions = {}
+
+    def load_standard_extensions(self, dirpath):
+        for ext in self.STANDARD_EXTENSIONS:
+            self.load(dirpath, ext)
+
+    def load(self, dirpath, filename):
+        with open(pathlib.Path(dirpath) / filename.strip("/")) as f:
+            sections = yaml.safe_load(f)
+
+        loaded_functions = set()
+        for functions in sections.values():
+            for function in functions:
+                function_name = function["name"]
+                for impl in function.get("impls", []):
+                    argtypes = [t.get("value", "unknown") for t in impl.get("args", [])]
+                    if not argtypes:
+                        signature = function_name
+                    else:
+                        signature = f"{function_name}:{'_'.join(argtypes)}"
+                    self._declarations[signature] = filename
+                    loaded_functions.add(signature)
+
+        self._register_extensions(filename, loaded_functions)
+
+    def _register_extensions(self, extension_uri, loaded_functions):
+        if extension_uri not in self._registered_extensions:
+            ext_anchor_id = len(self._registered_extensions) + 1
+            self._registered_extensions[extension_uri] = proto.SimpleExtensionURI(
+                extension_uri_anchor=ext_anchor_id, uri=extension_uri
+            )
+
+        for function in loaded_functions:
+            if function in self._functions:
+                extensions_by_anchor = self.extension_uris_by_anchor
+                function = self._functions[function]
+                function_extension = extensions_by_anchor[
+                    function.extension_uri_reference
+                ].uri
+                continue
+                raise ValueError(
+                    f"Duplicate function definition: {function} from {extension_uri}, already loaded from {function_extension}"
+                )
+            extension_anchor = self._registered_extensions[
+                extension_uri
+            ].extension_uri_anchor
+            function_anchor = len(self._functions) + 1
+            self._functions[function] = (
+                proto.SimpleExtensionDeclaration.ExtensionFunction(
+                    extension_uri_reference=extension_anchor,
+                    name=function,
+                    function_anchor=function_anchor,
+                )
+            )
+
+    @property
+    def extension_uris_by_anchor(self):
+        return {
+            ext.extension_uri_anchor: ext
+            for ext in self._registered_extensions.values()
+        }
+
+    @property
+    def extension_uris(self):
+        return list(self._registered_extensions.values())
+
+    @property
+    def extensions(self):
+        return list(self._functions.values())
+
+    def function_anchor(self, function):
+        return self._functions[function].function_anchor
+
+    def extensions_for_functions(self, functions):
+        uris_anchors = set()
+        extensions = []
+        for f in functions:
+            ext = self._functions[f]
+            uris_anchors.add(ext.extension_uri_reference)
+            extensions.append(proto.SimpleExtensionDeclaration(extension_function=ext))
+
+        uris_by_anchor = self.extension_uris_by_anchor
+        extension_uris = [uris_by_anchor[uri_anchor] for uri_anchor in uris_anchors]
+        return extension_uris, extensions
+
+
+catalog = FunctionsCatalog()
+catalog.load_standard_extensions(
+    pathlib.Path(__file__).parent.parent / "third_party" / "substrait" / "extensions",
+)
+schema = proto.NamedStruct(
+    names=["first_name", "surname", "age"],
+    struct=proto.Type.Struct(
+        types=[
+            proto.Type(
+                string=proto.Type.String(
+                    nullability=proto.Type.Nullability.NULLABILITY_REQUIRED
+                )
+            ),
+            proto.Type(
+                string=proto.Type.String(
+                    nullability=proto.Type.Nullability.NULLABILITY_REQUIRED
+                )
+            ),
+            proto.Type(
+                i32=proto.Type.I32(
+                    nullability=proto.Type.Nullability.NULLABILITY_REQUIRED
+                )
+            ),
+        ]
+    ),
+)
+
+if __name__ == '__main__':
+    sql = "SELECT surname, age + 1 as next_birthday WHERE age = 32"
+    projection_expr, filter_expr = parse_sql_extended_expression(catalog, schema, sql)
+    print("---- SQL INPUT ----")
+    print(sql)
+    print("---- PROJECTION ----")
+    print(projection_expr)
+    print("---- FILTER ----")
+    print(filter_expr)
+    # parse_extended_expression("INSERT INTO table VALUES(1, 2, 3)")