protobuf: Index | Files

package filetype

import ""

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


Package Files


type Builder Uses

type Builder struct {
    // File is the underlying file descriptor builder.
    File fdesc.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" concatenated back-to-back:
    //	0. Message field dependencies: list of the enum or message type
    //	referred to by every message field.
    //	1. Extension field targets: list of the extended parent message of
    //	every extension.
    //	2. Extension field dependencies: list of the enum or message type
    //	referred to by every extension field.
    //	3. Service method inputs: list of the input message type
    //	referred to by every service method.
    //	4. Service method outputs: list of the output message type
    //	referred to by every service method.
    // The offset into DependencyIndexes for the start of each sub-list
    // is appended to the end in reverse order.
    DependencyIndexes []int32

    // EnumInfos is a list of enum infos in "flattened ordering".
    EnumInfos []pimpl.EnumInfo

    // MessageInfos is a list of message infos in "flattened ordering".
    // If provided, the GoType and PBType for each element is populated.
    // Requirement: len(MessageInfos) == len(Build.Messages)
    MessageInfos []pimpl.MessageInfo

    // ExtensionInfos is a list of extension infos in "flattened ordering".
    // Each element is initialized and registered with the protoregistry package.
    // Requirement: len(LegacyExtensions) == len(Build.Extensions)
    ExtensionInfos []pimpl.ExtensionInfo

    // TypeRegistry is the registry to register each type descriptor.
    // If nil, it uses protoregistry.GlobalTypes.
    TypeRegistry interface {
        RegisterMessage(pref.MessageType) error
        RegisterEnum(pref.EnumType) error
        RegisterExtension(pref.ExtensionType) error

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.

func (Builder) Build Uses

func (tb Builder) Build() (out Out)

type Out Uses

type Out struct {
    File pref.FileDescriptor

Out is the output of the builder.

Package filetype imports 6 packages (graph) and is imported by 2 packages. Updated 2020-09-11. Refresh now. Tools for package owners.