You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: build.go
    path of file: ./repos/plumber/vendor/google.golang.org/protobuf/internal/filetype
    
    the code of the file until where you have to start completion: // Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package filetype provides functionality for wrapping descriptors
// with Go type information.
package filetype

import (
	"reflect"

	"google.golang.org/protobuf/internal/descopts"
	"google.golang.org/protobuf/internal/filedesc"
	pimpl "google.golang.org/protobuf/internal/impl"
	"google.golang.org/protobuf/reflect/protoreflect"
	"google.golang.org/protobuf/reflect/protoregistry"
)

// Builder constructs type descriptors from a raw file descriptor
// and associated Go types for each enum and message declaration.
//
// # Flattened Ordering
//
// The protobuf type system represents declarations as a tree. Certain nodes in
// the tree require us to either associate it with a concrete Go type or to
// resolve a dependency, which is information that must be provided separately
// since it cannot be derived from the file descriptor alone.
//
// However, representing a tree as Go literals is difficult to simply do in a
// space and time efficient way. Thus, we store them as a flattened list of
// objects where the serialization order from the tree-based form is important.
//
// The "flattened ordering" is defined as a tree traversal of all enum, message,
// extension, and service declarations using the following algorithm:
//
//	def VisitFileDecls(fd):
//		for e in fd.Enums:      yield e
//		for m in fd.Messages:   yield m
//		for x in fd.Extensions: yield x
//		for s in fd.Services:   yield s
//		for m in fd.Messages:   yield from VisitMessageDecls(m)
//
//	def VisitMessageDecls(md):
//		for e in md.Enums:      yield e
//		for m in md.Messages:   yield m
//		for x in md.Extensions: yield x
//		for m in md.Messages:   yield from VisitMessageDecls(m)
//
// The traversal starts at the root file descriptor and yields each direct
// declaration within each node before traversing into sub-declarations
// that children themselves may have.
type Builder struct {
	// File is the underlying file descriptor builder.
	File filedesc.Builder

	// GoTypes is a unique set of the Go types for all declarations and
	// dependencies. Each type is represented as a zero value of the Go type.
	//
	// Declarations are Go types generated for enums and messages directly
	// declared (not publicly imported) in the proto source file.
	// Messages for map entries are accounted for, but represented by nil.
	// Enum declarations in "flattened ordering" come first, followed by
	// message declarations in "flattened ordering".
	//
	// Dependencies are Go types for enums or messages referenced by
	// message fields (excluding weak fields), for parent extended messages of
	// extension fields, for enums or messages referenced by extension fields,
	// and for input and output messages referenced by service methods.
	// Dependencies must come after declarations, but the ordering of
	// dependencies themselves is unspecified.
	GoTypes []interface{}

	// DependencyIndexes is an ordered list of indexes into GoTypes for the
	// dependencies of messages, extensions, or services.
	//
	// There are 5 sub-lists in "flattened ordering" concate
    
func (tb Builder) Build() (out Out) {
	// Replace the resolver with one that resolves dependencies by index,
	// which is faster and more reliable than relying on the global registry.
	if tb.File.FileRegistry == nil {
		tb.File.FileRegistry = protoregistry.GlobalFiles
	}
	tb.File.FileRegistry = &resolverByIndex{
		goTypes:      tb.GoTypes,
		depIdxs:      tb.DependencyIndexes,
		fileRegistry: tb.File.FileRegistry,
	}

	// Initialize registry if unpopulated.
	if tb.TypeRegistry == nil {
		tb.TypeRegistry = protoregistry.GlobalTypes
	}

	fbOut := tb.File.Build()
	out.File = fbOut.File

	// Process enums.
	enumGoTypes := tb.GoTypes[:len(fbOut.Enums)]
	if len(tb.EnumInfos) != len(fbOut.Enums) {
		panic("mismatching enum lengths")
	}
	if len(fbOut.Enums) > 0 {
		for i := range fbOut.Enums {
			tb.EnumInfos[i] = pimpl.EnumInfo{
				GoReflectType: reflect.TypeOf(enumGoTypes[i]),
				Desc:          &fbOut.Enums[i],
			}
			// Register enum types.
			if err := tb.TypeRegistry.RegisterEnum(&tb.EnumInfos[i]); err != nil {
				panic(err)
			}
		}
	}

	// Process messages.
	messageGoTypes := tb.GoTypes[len(fbOut.Enums):][:len(fbOut.Messages)]
	if len(tb.MessageInfos) != len(fbOut.Messages) {
		panic("mismatching message lengths")
	}
	if len(fbOut.Messages) > 0 {
		for i := range fbOut.Messages {
			if messageGoTypes[i] == nil {
				continue // skip map entry
			}

			tb.MessageInfos[i].GoReflectType = reflect.TypeOf(messageGoTypes[i])
			tb.MessageInfos[i].Desc = &fbOut.Messages[i]

			// Register message types.
			if err := tb.TypeRegistry.RegisterMessage(&tb.MessageInfos[i]); err != nil {
				panic(err)
			}
		}

		// As a special-case for descriptor.proto,
		// locally register concrete message type for the options.
		if out.File.Path() == "google/protobuf/descriptor.proto" && out.File.Package() == "google.protobuf" {
			for i := range fbOut.Messages {
				switch fbOut.Messages[i].Name() {
				case "FileOptions":
					descopts.File = messageGoTypes[i].(protoreflect.ProtoMessage)
				case "EnumOptions":
					descopts.Enum = messageGoTypes[i].(protoreflect.ProtoMessage)
				case "EnumValueOptions":
					descopts.EnumValue = messageGoTypes[i].(protoreflect.ProtoMessage)
				case "MessageOptions":
					descopts.Message = messageGoTypes[i].(protoreflect.ProtoMessage)
				case "FieldOptions":
					descopts.Field = messageGoTypes[i].(protoreflect.ProtoMessage)
				case "OneofOptions":
					descopts.Oneof = messageGoTypes[i].(protoreflect.ProtoMessage)
				case "ExtensionRangeOptions":
					descopts.ExtensionRange = messageGoTypes[i].(protoreflect.ProtoMessage)
				case "ServiceOptions":
					descopts.Service = messageGoTypes[i].(protoreflect.ProtoMessage)
				case "MethodOptions":
					descopts.Method = messageGoTypes[i].(protoreflect.ProtoMessage)
				}
			}
		}
	}

	// Process extensions.
	if len(tb.ExtensionInfos) != len(fbOut.Extensions) {
		panic("mismatching extension lengths")
	}
	var depIdx int32
	for i := range fbOut.Extensions {
		// For enum and message kinds, determine the referent Go type so
		// that we can construct their constructors.
		const listExtDeps = 2
		var goType reflect.Type
		switch fbOut.Extensions[i].L1.Kind {
		case protoreflect.EnumKind:
			j := depIdxs.Get(tb.DependencyIndexes, listExtDeps, depIdx)
			goType = reflect.TypeOf(tb.GoTypes[j])
			depIdx++
		case protoreflect.MessageKind, protoreflect.GroupKind:
			j := depIdxs.Get(tb.DependencyIndexes, listExtDeps, depIdx)
			goType = reflect.TypeOf(tb.GoTypes[j])
			depIdx++
		default:
			goType = goTypeForPBKind[fbOut.Extensions[i].L1.Kind]
		}
		if fbOut.Extensions[i].IsList() {
			goType = reflect.SliceOf(goType)
		}

		pimpl.InitExtensionInfo(&tb.ExtensionInfos[i], &fbOut.Extensions[i], goType)

		// Register extension types.
		if err := tb.TypeRegistry.RegisterExtension(&tb.ExtensionInfos[i]); err != nil {
			panic(err)
		}
	}

	return out
}