chore: import upstream snapshot with attribution

core/functions/serialization.go

@@ -0,0 +1,118 @@
+// Copyright 2024 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 functions
+
+import (
+	"context"
+
+	"github.com/cockroachdb/errors"
+
+	"github.com/dolthub/doltgresql/core/id"
+	"github.com/dolthub/doltgresql/server/plpgsql"
+	"github.com/dolthub/doltgresql/utils"
+)
+
+// Serialize returns the Function as a byte slice. If the Function is invalid, then this returns a nil slice.
+func (function Function) Serialize(ctx context.Context) ([]byte, error) {
+	if !function.ID.IsValid() {
+		return nil, nil
+	}
+
+	// Write all of the functions to the writer
+	writer := utils.NewWriter(256)
+	writer.VariableUint(3) // Version
+	// Write the function data
+	writer.Id(function.ID.AsId())
+	writer.Id(function.ReturnType.AsId())
+	writer.StringSlice(function.ParameterNames)
+	writer.IdTypeSlice(function.ParameterTypes)
+	writer.Bool(function.Variadic)
+	writer.Bool(function.IsNonDeterministic)
+	writer.Bool(function.Strict)
+	writer.String(function.Definition)
+	// Write the operations
+	writer.VariableUint(uint64(len(function.Operations)))
+	for _, op := range function.Operations {
+		writer.Uint16(uint16(op.OpCode))
+		writer.String(op.PrimaryData)
+		writer.StringSlice(op.SecondaryData)
+		writer.String(op.Target)
+		writer.Int32(int32(op.Index))
+		writer.StringMap(op.Options)
+	}
+	// Write version 1 data
+	writer.String(function.ExtensionName)
+	writer.String(function.ExtensionSymbol)
+	// Write version 2 data
+	writer.String(function.SQLDefinition)
+	writer.Bool(function.SetOf)
+	// Write version 3 data
+	writer.StringSlice(function.ParameterDefaults)
+	// Returns the data
+	return writer.Data(), nil
+}
+
+// DeserializeFunction returns the Function that was serialized in the byte slice. Returns an empty Function (invalid
+// ID) if data is nil or empty.
+func DeserializeFunction(ctx context.Context, data []byte) (Function, error) {
+	if len(data) == 0 {
+		return Function{}, nil
+	}
+	reader := utils.NewReader(data)
+	version := reader.VariableUint()
+	if version > 3 {
+		return Function{}, errors.Errorf("version %d of functions is not supported, please upgrade the server", version)
+	}
+
+	// Read from the reader
+	f := Function{}
+	f.ID = id.Function(reader.Id())
+	f.ReturnType = id.Type(reader.Id())
+	f.ParameterNames = reader.StringSlice()
+	f.ParameterTypes = reader.IdTypeSlice()
+	f.Variadic = reader.Bool()
+	f.IsNonDeterministic = reader.Bool()
+	f.Strict = reader.Bool()
+	f.Definition = reader.String()
+	// Read the operations
+	opCount := reader.VariableUint()
+	f.Operations = make([]plpgsql.InterpreterOperation, opCount)
+	for opIdx := uint64(0); opIdx < opCount; opIdx++ {
+		op := plpgsql.InterpreterOperation{}
+		op.OpCode = plpgsql.OpCode(reader.Uint16())
+		op.PrimaryData = reader.String()
+		op.SecondaryData = reader.StringSlice()
+		op.Target = reader.String()
+		op.Index = int(reader.Int32())
+		op.Options = reader.StringMap()
+		f.Operations[opIdx] = op
+	}
+	if version >= 1 {
+		f.ExtensionName = reader.String()
+		f.ExtensionSymbol = reader.String()
+	}
+	if version >= 2 {
+		f.SQLDefinition = reader.String()
+		f.SetOf = reader.Bool()
+	}
+	if version >= 3 {
+		f.ParameterDefaults = reader.StringSlice()
+	}
+	if !reader.IsEmpty() {
+		return Function{}, errors.Errorf("extra data found while deserializing a function")
+	}
+	// Return the deserialized object
+	return f, nil
+}