source: code/trunk/vendor/google.golang.org/protobuf/reflect/protodesc/desc.go@ 822

// Copyright 2018 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 protodesc provides functionality for converting
// FileDescriptorProto messages to/from protoreflect.FileDescriptor values.
//
// The google.protobuf.FileDescriptorProto is a protobuf message that describes
// the type information for a .proto file in a form that is easily serializable.
// The protoreflect.FileDescriptor is a more structured representation of
// the FileDescriptorProto message where references and remote dependencies
// can be directly followed.
package protodesc

import (
        "google.golang.org/protobuf/internal/errors"
        "google.golang.org/protobuf/internal/filedesc"
        "google.golang.org/protobuf/internal/pragma"
        "google.golang.org/protobuf/internal/strs"
        "google.golang.org/protobuf/proto"
        "google.golang.org/protobuf/reflect/protoreflect"
        "google.golang.org/protobuf/reflect/protoregistry"

        "google.golang.org/protobuf/types/descriptorpb"
)

// Resolver is the resolver used by NewFile to resolve dependencies.
// The enums and messages provided must belong to some parent file,
// which is also registered.
//
// It is implemented by protoregistry.Files.
type Resolver interface {
        FindFileByPath(string) (protoreflect.FileDescriptor, error)
        FindDescriptorByName(protoreflect.FullName) (protoreflect.Descriptor, error)
}

// FileOptions configures the construction of file descriptors.
type FileOptions struct {
        pragma.NoUnkeyedLiterals

        // AllowUnresolvable configures New to permissively allow unresolvable
        // file, enum, or message dependencies. Unresolved dependencies are replaced
        // by placeholder equivalents.
        //
        // The following dependencies may be left unresolved:
        //      • Resolving an imported file.
        //      • Resolving the type for a message field or extension field.
        //      If the kind of the field is unknown, then a placeholder is used for both
        //      the Enum and Message accessors on the protoreflect.FieldDescriptor.
        //      • Resolving an enum value set as the default for an optional enum field.
        //      If unresolvable, the protoreflect.FieldDescriptor.Default is set to the
        //      first value in the associated enum (or zero if the also enum dependency
        //      is also unresolvable). The protoreflect.FieldDescriptor.DefaultEnumValue
        //      is populated with a placeholder.
        //      • Resolving the extended message type for an extension field.
        //      • Resolving the input or output message type for a service method.
        //
        // If the unresolved dependency uses a relative name,
        // then the placeholder will contain an invalid FullName with a "*." prefix,
        // indicating that the starting prefix of the full name is unknown.
        AllowUnresolvable bool
}

// NewFile creates a new protoreflect.FileDescriptor from the provided
// file descriptor message. See FileOptions.New for more information.
func NewFile(fd *descriptorpb.FileDescriptorProto, r Resolver) (protoreflect.FileDescriptor, error) {
        return FileOptions{}.New(fd, r)
}

// NewFiles creates a new protoregistry.Files from the provided
// FileDescriptorSet message. See FileOptions.NewFiles for more information.
func NewFiles(fd *descriptorpb.FileDescriptorSet) (*protoregistry.Files, error) {
        return FileOptions{}.NewFiles(fd)
}

// New creates a new protoreflect.FileDescriptor from the provided
// file descriptor message. The file must represent a valid proto file according
// to protobuf semantics. The returned descriptor is a deep copy of the input.
//
// Any imported files, enum types, or message types referenced in the file are
// resolved using the provided registry. When looking up an import file path,
// the path must be unique. The newly created file descriptor is not registered
// back into the provided file registry.
func (o FileOptions) New(fd *descriptorpb.FileDescriptorProto, r Resolver) (protoreflect.FileDescriptor, error) {
        if r == nil {
                r = (*protoregistry.Files)(nil) // empty resolver
        }

        // Handle the file descriptor content.
        f := &filedesc.File{L2: &filedesc.FileL2{}}
        switch fd.GetSyntax() {
        case "proto2", "":
                f.L1.Syntax = protoreflect.Proto2
        case "proto3":
                f.L1.Syntax = protoreflect.Proto3
        default:
                return nil, errors.New("invalid syntax: %q", fd.GetSyntax())
        }
        f.L1.Path = fd.GetName()
        if f.L1.Path == "" {
                return nil, errors.New("file path must be populated")
        }
        f.L1.Package = protoreflect.FullName(fd.GetPackage())
        if !f.L1.Package.IsValid() && f.L1.Package != "" {
                return nil, errors.New("invalid package: %q", f.L1.Package)
        }
        if opts := fd.GetOptions(); opts != nil {
                opts = proto.Clone(opts).(*descriptorpb.FileOptions)
                f.L2.Options = func() protoreflect.ProtoMessage { return opts }
        }

        f.L2.Imports = make(filedesc.FileImports, len(fd.GetDependency()))
        for _, i := range fd.GetPublicDependency() {
                if !(0 <= i && int(i) < len(f.L2.Imports)) || f.L2.Imports[i].IsPublic {
                        return nil, errors.New("invalid or duplicate public import index: %d", i)
                }
                f.L2.Imports[i].IsPublic = true
        }
        for _, i := range fd.GetWeakDependency() {
                if !(0 <= i && int(i) < len(f.L2.Imports)) || f.L2.Imports[i].IsWeak {
                        return nil, errors.New("invalid or duplicate weak import index: %d", i)
                }
                f.L2.Imports[i].IsWeak = true
        }
        imps := importSet{f.Path(): true}
        for i, path := range fd.GetDependency() {
                imp := &f.L2.Imports[i]
                f, err := r.FindFileByPath(path)
                if err == protoregistry.NotFound && (o.AllowUnresolvable || imp.IsWeak) {
                        f = filedesc.PlaceholderFile(path)
                } else if err != nil {
                        return nil, errors.New("could not resolve import %q: %v", path, err)
                }
                imp.FileDescriptor = f

                if imps[imp.Path()] {
                        return nil, errors.New("already imported %q", path)
                }
                imps[imp.Path()] = true
        }
        for i := range fd.GetDependency() {
                imp := &f.L2.Imports[i]
                imps.importPublic(imp.Imports())
        }

        // Handle source locations.
        f.L2.Locations.File = f
        for _, loc := range fd.GetSourceCodeInfo().GetLocation() {
                var l protoreflect.SourceLocation
                // TODO: Validate that the path points to an actual declaration?
                l.Path = protoreflect.SourcePath(loc.GetPath())
                s := loc.GetSpan()
                switch len(s) {
                case 3:
                        l.StartLine, l.StartColumn, l.EndLine, l.EndColumn = int(s[0]), int(s[1]), int(s[0]), int(s[2])
                case 4:
                        l.StartLine, l.StartColumn, l.EndLine, l.EndColumn = int(s[0]), int(s[1]), int(s[2]), int(s[3])
                default:
                        return nil, errors.New("invalid span: %v", s)
                }
                // TODO: Validate that the span information is sensible?
                // See https://github.com/protocolbuffers/protobuf/issues/6378.
                if false && (l.EndLine < l.StartLine || l.StartLine < 0 || l.StartColumn < 0 || l.EndColumn < 0 ||
                        (l.StartLine == l.EndLine && l.EndColumn <= l.StartColumn)) {
                        return nil, errors.New("invalid span: %v", s)
                }
                l.LeadingDetachedComments = loc.GetLeadingDetachedComments()
                l.LeadingComments = loc.GetLeadingComments()
                l.TrailingComments = loc.GetTrailingComments()
                f.L2.Locations.List = append(f.L2.Locations.List, l)
        }

        // Step 1: Allocate and derive the names for all declarations.
        // This copies all fields from the descriptor proto except:
        //      google.protobuf.FieldDescriptorProto.type_name
        //      google.protobuf.FieldDescriptorProto.default_value
        //      google.protobuf.FieldDescriptorProto.oneof_index
        //      google.protobuf.FieldDescriptorProto.extendee
        //      google.protobuf.MethodDescriptorProto.input
        //      google.protobuf.MethodDescriptorProto.output
        var err error
        sb := new(strs.Builder)
        r1 := make(descsByName)
        if f.L1.Enums.List, err = r1.initEnumDeclarations(fd.GetEnumType(), f, sb); err != nil {
                return nil, err
        }
        if f.L1.Messages.List, err = r1.initMessagesDeclarations(fd.GetMessageType(), f, sb); err != nil {
                return nil, err
        }
        if f.L1.Extensions.List, err = r1.initExtensionDeclarations(fd.GetExtension(), f, sb); err != nil {
                return nil, err
        }
        if f.L1.Services.List, err = r1.initServiceDeclarations(fd.GetService(), f, sb); err != nil {
                return nil, err
        }

        // Step 2: Resolve every dependency reference not handled by step 1.
        r2 := &resolver{local: r1, remote: r, imports: imps, allowUnresolvable: o.AllowUnresolvable}
        if err := r2.resolveMessageDependencies(f.L1.Messages.List, fd.GetMessageType()); err != nil {
                return nil, err
        }
        if err := r2.resolveExtensionDependencies(f.L1.Extensions.List, fd.GetExtension()); err != nil {
                return nil, err
        }
        if err := r2.resolveServiceDependencies(f.L1.Services.List, fd.GetService()); err != nil {
                return nil, err
        }

        // Step 3: Validate every enum, message, and extension declaration.
        if err := validateEnumDeclarations(f.L1.Enums.List, fd.GetEnumType()); err != nil {
                return nil, err
        }
        if err := validateMessageDeclarations(f.L1.Messages.List, fd.GetMessageType()); err != nil {
                return nil, err
        }
        if err := validateExtensionDeclarations(f.L1.Extensions.List, fd.GetExtension()); err != nil {
                return nil, err
        }

        return f, nil
}

type importSet map[string]bool

func (is importSet) importPublic(imps protoreflect.FileImports) {
        for i := 0; i < imps.Len(); i++ {
                if imp := imps.Get(i); imp.IsPublic {
                        is[imp.Path()] = true
                        is.importPublic(imp.Imports())
                }
        }
}

// NewFiles creates a new protoregistry.Files from the provided
// FileDescriptorSet message. The descriptor set must include only
// valid files according to protobuf semantics. The returned descriptors
// are a deep copy of the input.
func (o FileOptions) NewFiles(fds *descriptorpb.FileDescriptorSet) (*protoregistry.Files, error) {
        files := make(map[string]*descriptorpb.FileDescriptorProto)
        for _, fd := range fds.File {
                if _, ok := files[fd.GetName()]; ok {
                        return nil, errors.New("file appears multiple times: %q", fd.GetName())
                }
                files[fd.GetName()] = fd
        }
        r := &protoregistry.Files{}
        for _, fd := range files {
                if err := o.addFileDeps(r, fd, files); err != nil {
                        return nil, err
                }
        }
        return r, nil
}
func (o FileOptions) addFileDeps(r *protoregistry.Files, fd *descriptorpb.FileDescriptorProto, files map[string]*descriptorpb.FileDescriptorProto) error {
        // Set the entry to nil while descending into a file's dependencies to detect cycles.
        files[fd.GetName()] = nil
        for _, dep := range fd.Dependency {
                depfd, ok := files[dep]
                if depfd == nil {
                        if ok {
                                return errors.New("import cycle in file: %q", dep)
                        }
                        continue
                }
                if err := o.addFileDeps(r, depfd, files); err != nil {
                        return err
                }
        }
        // Delete the entry once dependencies are processed.
        delete(files, fd.GetName())
        f, err := o.New(fd, r)
        if err != nil {
                return err
        }
        return r.RegisterFile(f)
}