chore: import upstream snapshot with attribution

server/functions/framework/c_function.go

@@ -0,0 +1,90 @@
+// Copyright 2025 Dolthub, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package framework
+
+import (
+	"github.com/dolthub/doltgresql/core/extensions"
+	"github.com/dolthub/doltgresql/core/id"
+	pgtypes "github.com/dolthub/doltgresql/server/types"
+)
+
+// CFunction is the implementation of functions that host their logic in a shared library.
+type CFunction struct {
+	ID                 id.Function
+	ReturnType         *pgtypes.DoltgresType
+	ParameterTypes     []*pgtypes.DoltgresType
+	Variadic           bool
+	IsNonDeterministic bool
+	Strict             bool
+	ExtensionName      extensions.LibraryIdentifier
+	ExtensionSymbol    string
+}
+
+var _ FunctionInterface = CFunction{}
+
+// GetExpectedParameterCount implements the interface FunctionInterface.
+func (cFunc CFunction) GetExpectedParameterCount() int {
+	return len(cFunc.ParameterTypes)
+}
+
+// GetName implements the interface FunctionInterface.
+func (cFunc CFunction) GetName() string {
+	return cFunc.ID.FunctionName()
+}
+
+// GetParameters implements the interface FunctionInterface.
+func (cFunc CFunction) GetParameters() []*pgtypes.DoltgresType {
+	return cFunc.ParameterTypes
+}
+
+// GetReturn implements the interface FunctionInterface.
+func (cFunc CFunction) GetReturn() *pgtypes.DoltgresType {
+	return cFunc.ReturnType
+}
+
+// InternalID implements the interface FunctionInterface.
+func (cFunc CFunction) InternalID() id.Id {
+	return cFunc.ID.AsId()
+}
+
+// IsStrict implements the interface FunctionInterface.
+func (cFunc CFunction) IsStrict() bool {
+	return cFunc.Strict
+}
+
+// NonDeterministic implements the interface FunctionInterface.
+func (cFunc CFunction) NonDeterministic() bool {
+	return cFunc.IsNonDeterministic
+}
+
+// IsCVariadic implements the FunctionInterface interface.
+func (cFunc CFunction) IsCVariadic() bool {
+	// TODO: implement c-language variadic
+	return false
+}
+
+// VariadicIndex implements the interface FunctionInterface.
+func (cFunc CFunction) VariadicIndex() int {
+	// TODO: implement variadic
+	return -1
+}
+
+// IsSRF implements the interface FunctionInterface.
+func (cFunc CFunction) IsSRF() bool {
+	return false
+}
+
+// enforceInterfaceInheritance implements the interface FunctionInterface.
+func (cFunc CFunction) enforceInterfaceInheritance(error) {}