299 Commits

Author SHA1 Message Date
Joe Tsai
f18ab539ab all: make use of the protoapi package in v1
The new v1 protoapi package enables:
* Referencing types in the protoapi package instead of protoV1, which further
reduces the number of situations where we need to depend on protoV1.
This is for the goal of eventually breaking all cases where the v2 implementation
relies on v1, so that in the near future, proto v1 can rely on proto v2 instead.
* Removes the need for legacy_extension_hack.go since that functionality has now
been exported into the protoapi package.

Change-Id: If71002d9ec711bfabfe494636829df9abf19e23e
Reviewed-on: https://go-review.googlesource.com/c/151403
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-29 22:46:29 +00:00
Joe Tsai
25cc69d405 internal/impl: fix legacy logic to know about the new XXX_OneofWrappers method
The XXX_OneofWrappers method is a simplified way to obtain the wrapper structs
compared the previous XXX_OneofFuncs method which returned far more information
that was strictly necessary.

Change-Id: I2670506a2a8f7e8e724846b8c4083e7995371007
Reviewed-on: https://go-review.googlesource.com/c/151679
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-29 08:04:36 +00:00
Joe Tsai
71acbc7b7d internal/detrand: support disabling detrand
Since detrand is an internal package, we can safely provide a function
that can be called to disable its functionality for testing purposes.

Change-Id: I26383e12a5832eb5af01952898a4c73f627d7aa5
Reviewed-on: https://go-review.googlesource.com/c/151678
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-29 07:49:45 +00:00
Joe Tsai
009e067ed8 internal/scalar: add scalar package for primitive wrappers
Add the scalar package to reduce dependencies on the v1 proto runtime package.
It may very well be the case that these functions should be exposed in the
public API of v2, but that is not a decision we need to make now.

Change-Id: Ifbc6d15311ba5837909ac72af47c630a80a142ef
Reviewed-on: https://go-review.googlesource.com/c/151402
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-28 07:06:11 +00:00
Joe Tsai
f757390b52 cmd/protoc-gen-go: remove generation of RegisterMessageSetType
PR#741 in the v1 repository deprecated this behavior.

Change-Id: Ife48f1d586f178d875b9b3002a88b3336a2cd3b4
Reviewed-on: https://go-review.googlesource.com/c/151401
Reviewed-by: Damien Neil <dneil@google.com>
2018-11-28 00:40:08 +00:00
Joe Tsai
b6dbf23033 cmd/protoc-gen-go: remove generation of {Unmarshal,Marshal}JSON for MessageSets
PR#741 in the v1 repository deprecated this behavior.

Change-Id: Idffa3884d43f9cc5528ce8d9f303676e0e501b67
Reviewed-on: https://go-review.googlesource.com/c/151400
Reviewed-by: Damien Neil <dneil@google.com>
2018-11-27 23:47:23 +00:00
Joe Tsai
411f33952f protogen: clarify that GoIdent.GoName is a single idenfitier
While we're at it, also add the license header for the file.

Change-Id: If33f1764111aff96efcdb5a4e88c2a70ae28c09c
Reviewed-on: https://go-review.googlesource.com/c/150060
Reviewed-by: Damien Neil <dneil@google.com>
2018-11-27 19:56:42 +00:00
Joe Tsai
d7e97bc71b cmd/protoc-gen-go: generate XXX_OneofWrappers instead of XXX_OneofFuncs
The marshaler, unmarshaler, and sizer functions are unused ever since
the underlying implementation was switched to be table-driven.
Change the function to only return the wrapper structs.

This change:
* enables generated protos to drop dependencies on certain proto types
* reduces the size of generated protos
* simplifies the implementation of oneofs in protoc-gen-go

Updates #708

Change-Id: I845c9009bc0236d1b51d34b014dc3e184303c0f2
Reviewed-on: https://go-review.googlesource.com/c/151357
Reviewed-by: Damien Neil <dneil@google.com>
2018-11-27 19:36:27 +00:00
Joe Tsai
f6d4a4215f reflect/protoreflect: clarify Get semantics on unpopulated fields
Clearly specify that Get on an unpopulated field:
* returns the default value for scalars
* returns a mutable (but empty) List for repeated fields
* returns a mutable (but empty) Map for map fields
* returns an invalid value for message fields

The difference in semantics between List+Maps and Messages is because
protobuf semantics provide no distinction between an unpopulated and empty list
or map. On the other hand, there is a semantic difference between an unpopulated
message and an empty message.

Default values for scalars is trivial to implement with FieldDescriptor.Default.

A mutable, but empty List and Map is easy to implement for known fields since
known fields are generated as a slice or map field in a struct.
Since struct fields are addressable, the implementation can just return a
reference to the slice or map.

Repeated, extension fields are a little more tricky since extension fields
are implemented under the hood as a map[FieldNumber]Extension.
Rather than allocating an empty list in KnownFields.Get upon first retrieval
(which presents a race), delegate the work to ExtensionFieldTypes.Register,
which must occur before any Get operation. Register is not a concurrent-safe
operation, so that is an excellent time to initilize empty lists.
The implementation of extensions will need to be careful that Clear on a repeated
field simply truncates it zero instead of deleting the object.

For unpopulated messages, we return an invalid value, instead of the prior
behavior of returning a typed nil-pointer to the Go type for the message.
The approach is problematic because it assumes that
1) all messages are always implemented on a pointer reciever
2) a typed nil-pointer is an appropriate "read-only, but empty" message
These assumptions are not true of all message types (e.g., dynamic messages).

Change-Id: Ie96e6744c890308d9de738b6cf01d3b19e7e7c6a
Reviewed-on: https://go-review.googlesource.com/c/150319
Reviewed-by: Damien Neil <dneil@google.com>
2018-11-27 19:13:59 +00:00
Joe Tsai
492a476312 internal/detrand: new package for deterministically random functionality
The use of math/rand in serialization is to provide some form of instability
to the output to provide a clear signal to the user that the should not
depend on the the property of stability. However, it is reasonable that users
expect the output for these to be deterministic.

As such, add a detrand package that provides deterministic, yet unstable
randomization functionality.

Since this package hashes the binary, it does impose a small initialization cost:
	Benchmark    100000    20712 ns/op    480 B/op    6 allocs/op

Change-Id: I232d0fea1789a4278079837a67ee2f63474a4364
Reviewed-on: https://go-review.googlesource.com/c/151340
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-27 02:14:04 +00:00
Herbie Ong
c3f4d48629 internal/encoding/text: add extra random space to make output unstable.
Make output deliberately unstable so users don't rely on exactness.

For multi-line output, add another extra random space after <key>: for
at most one field per message.

-- example --
key1: field1
key2:  {
    foo:  bar
}

For single-line output, add another extra random space after a field per
message.

-- example --
key1:field1  key2:{foo:bar}

Change-Id: I3ab25d4d970fdebb88bbd9dd8fa6d73af84338ea
Reviewed-on: https://go-review.googlesource.com/c/150977
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
2018-11-27 00:46:16 +00:00
Joe Tsai
ccf645912d reflect/prototype: print {Enum,Message,Extension}Type.GoType
Add GoType to the list of accessors that can be pretty-printed.
Useful for debugging.

Change-Id: Ib2a240249ca5bf0176cb77fa5edc639d44ae0561
Reviewed-on: https://go-review.googlesource.com/c/150537
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-20 20:02:59 +00:00
Joe Tsai
44e389ca6c internal/impl: fix Has for proto3 scalars
The definition of Has for proto3 scalars is whether the value is non-zero.

Change-Id: I6aee92dd518d63a66515ad35da84b2be7aa22527
Reviewed-on: https://go-review.googlesource.com/c/150320
Reviewed-by: Herbie Ong <herbie@google.com>
Reviewed-by: Joe Tsai <joetsai@google.com>
2018-11-19 23:34:00 +00:00
Joe Tsai
c6320b9f23 test.bash: update to go1.10.5 and go1.11.2
Change-Id: Ie62569d8544e262689dced53e9701859871962d9
Reviewed-on: https://go-review.googlesource.com/c/150076
Reviewed-by: Andrew Bonventre <andybons@golang.org>
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-19 18:05:39 +00:00
Joe Tsai
c1c17aa013 protogen: add GoImportPath.Ident helper
The GoImportPath.Ident helper creates a GoIdent using the receiver
as the GoImportPath in the GoIdent. This helper helps with the construction
of qualified identifiers.

Example usage:
	const protoPackage = protogen.GoImportPath("github.com/golang/protobuf/proto")
	protoPackage.Ident("ExtensionRange") // produces "proto.ExtensionRange"

The advantage of this helper is that usage of it looks similar to how
the identifier will eventually be rendered.

This is significantly more readable than the current approach:
	protogen.GoIdent{
		GoImportPath: protoPackage,
		GoName: "ExtensionRange",
	}

Change-Id: If7ecd7e60fad12bc491eee0dcb05f8fdebc9c94e
Reviewed-on: https://go-review.googlesource.com/c/150058
Reviewed-by: Damien Neil <dneil@google.com>
2018-11-16 19:34:14 +00:00
Joe Tsai
87b955ba7f internal/impl: add extensive tests for enum and messages
Add more extensive tests to ensure that the reflective API works for both
enums and messages. We tests the situation where a v2 message has dependencies
on v1 messages and vice versa.

Change-Id: Ib85d465711728ae13743bea700b678d9dda5e85c
Reviewed-on: https://go-review.googlesource.com/c/149758
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-15 23:10:55 +00:00
Joe Tsai
a31649d331 internal/impl: remove hack in legacy_extension_hack.go
This hack has now been upstreamed in the v1 codebase;
there is no longer any need to maintain the code in v2.
See https://github.com/golang/protobuf/pull/746

Change-Id: I2c59d11303f5465e65190d893c422c088c647691
Reviewed-on: https://go-review.googlesource.com/c/149659
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-15 02:11:35 +00:00
Joe Tsai
4b7aff630a all: rename Vector as List
The terminology Vector does not occur in protobuf documentation at all,
so we should rename the Go use of the term to something more recognizable.
As such, all instances that match the regexp "[Vv]ect(or)?" were replaced.

The C++ documentation uses the term "Repeated", which is a reasonable name.
However, the term became overloaded in 2014, when maps were added as a feature
and implementated under the hood as repeated fields. This is confusing as it
means "repeated" could either refer to repeated fields proper (i.e., explicitly
marked with the "repeated" label in the proto file) or map fields. In the case
of the C++ reflective API, this is not a problem since repeated fields proper
and map fields are interacted with through the same RepeatedField type.

In Go, we do not use a single type to handle both types of repeated fields:
1) We are coming up with the Go protobuf reflection API for the first time
and so do not need to piggy-back on the repeated fields API to remain backwards
compatible since no former usages of Go protobuf reflection exists.
2) Map fields are commonly represented in Go as the Go map type, which do not
preserve ordering information. As such it is fundamentally impossible to present
an unordered map as a consistently ordered list. Thus, Go needs two different
interfaces for lists and maps.

Given the above situation, "Repeated" is not a great term to use since it
refers to two different things (when we only want one of the meanings).
To distinguish between the two, we'll use the terms "List" and "Map" instead.
There is some precedence for the term "List" in the protobuf codebase
(e.g., "getRepeatedInt32List").

Change-Id: Iddcdb6b78e1e60c14fa4ca213c15f45e214b967b
Reviewed-on: https://go-review.googlesource.com/c/149657
Reviewed-by: Damien Neil <dneil@google.com>
2018-11-14 23:03:53 +00:00
Joe Tsai
f0c01e459b internal/impl: support legacy extension fields
Implement support for extension fields for messages that use the v1
data structures for extensions. The legacyExtensionFields type wraps a
v1 map to implement the v2 protoreflect.KnownFields interface.

Working on this change revealed a bug in the dynamic construction of
message types for protobuf messages that had cyclic dependencies (e.g.,
message Foo has a sub-field of message Bar, and Bar has a sub-field of Foo).
In such a situation, a deadlock occurs because initialization code depends on
the very initialization code that is currently running. To break these cycles,
we make some systematic changes listed in the following paragraphs.
Generally speaking, we separate the logic for construction and wrapping,
where constuction does not recursively rely on dependencies,
while wrapping may recursively inspect dependencies.

Promote the MessageType.MessageOf method as a standalone MessageOf function
that dynamically finds the proper *MessageType to use. We make it such that
MessageType only supports two forms of messages types:
* Those that fully implement the v2 API.
* Those that do not implement the v2 API at all.
This removes support for the hybrid form that was exploited by message_test.go

In impl/message_test.go, switch each message to look more like how future
generated messages will look like. This is done in reaction to the fact that
MessageType.MessageOf no longer exists.

In value/{map,vector}.go, fix Unwrap to return a pointer since the underlying
reflect.Value is addressable reference value, not a pointer value.

In value/convert.go, split the logic apart so that obtaining a v2 type and
wrapping a type as v2 are distinct operations. Wrapping requires further
initialization than simply creating the initial message type, and calling it
during initial construction would lead to a deadlock.

In protoreflect/go_type.go, we switch back to a lazy initialization of GoType
to avoid a deadlock since the user-provided fn may rely on the fact that
prototype.GoMessage returned.

Change-Id: I5dea00e36fe1a9899bd2ac0aed2c8e51d5d87420
Reviewed-on: https://go-review.googlesource.com/c/148826
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-14 18:37:45 +00:00
Joe Tsai
ea11813c05 internal/testprotos/legacy: initial commit
Add a corpus of generated protobuf messages generated at specific versions
of protoc-gen-go to ensure that we continue to support for generated messages
that have may never be updated.

Change-Id: I04a1b74306f471d7c99f5daf52399a5bd9adcbbc
Reviewed-on: https://go-review.googlesource.com/c/148831
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-13 22:37:52 +00:00
Joe Tsai
6f9095c675 internal/value: expose Converter.{MessageType,EnumType}
Rather than having the Converter carry a NewMessage method, have the struct
simply expose the MessageType or EnumType since they carry more information
and are retrieved anyways as part of the functionality of NewConverter.
While changing Converter, export the fields and remove all the methods.
Also, add an IsLegacy boolean, which is useful for the later implementation
of the extension fields.

Add a wrapLegacyEnum function which is used to wrap v1 enums as v2 enums.
We use this functionality in NewLegacyConverter to detrive the EnumType.
Additionally, modify wrapLegacyMessage to return a protoreflect.ProtoMessage
to be consistent with wrapLegacyEnum which must return a protoreflect.ProtoEnum.

Change-Id: Idc8989d07e4895d30de4ebc22c9ffa7357815cad
Reviewed-on: https://go-review.googlesource.com/c/148827
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-12 22:59:43 +00:00
Joe Tsai
1c40f4957d reflect/prototype: simplify Go type descriptor constructors
The Go type descriptors protoreflect.{Enum,Message,Extension}Type are simple
wrappers over protoreflect.{Enum,Message,Extension}Descriptor with a small
number of additional methods. It is very unlikely that more will be added in
the near future.

For this reason, construct the types directly using arguments to the constructor
function, as opposed to taking in another struct (which was originally done
to provide flexibility in-case we needed more fields).

Furthmore, rename GoNew and New.

Change-Id: Ic7fb5bc250cdb2761ae03b388b5147ff50f37d15
Reviewed-on: https://go-review.googlesource.com/c/148822
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-10 21:41:49 +00:00
Joe Tsai
2cdb23da01 reflect/prototype: remove TODO about custom extensions constructors
Most usages extensions are only for fields that have a singular message
as the type. In such a sitation, the Go type and constructors are determined
by the provided protoreflect.MessageType and is certainly what the user wanted.

Custom extensions constructors are mainly useful if the user wants to use their
own type to represent repeated fields. For example, we use *[]T to represent
repeated fields, while a user may want to use their own opaque type.

However, this is such a niche use-case that it is not worth supporting given
that there is a workaround:

	type MyExtensionType struct {
		protoreflect.ExtensionType
	}
	func (x MyExtensionType) GoNew() interface{} {
		... // return my custom value
	}
	func (x MyExtensionType) GoType() reflect.Type {
		... // return my custom type
	}
	func (x MyExtensionType) ValueOf(v interface{}) protoreflect.Value {
		... // convert my custom type to a protoreflect.Value
	}
	func (x MyExtensionType) InterfaceOf(v protoreflect.Value) interface{} {
		... // convert a protoreflect.Value to my custom type
	}

Change-Id: Iafc838b1c95b0ffc8583461ee9eb327bd3ce9c3c
Reviewed-on: https://go-review.googlesource.com/c/148820
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-10 00:59:49 +00:00
Joe Tsai
34eb7ef6d5 reflect/protoreflect: clarify Clear and Remove operation on missing entries
Follow the precedence of Go maps where deletion on a key without an entry in
the map is a noop. Similarly, document that the following methods are safe
to call with entries that do not exist:
* Map.Clear
* KnownFields.Clear
* ExtensionFieldTypes.Remove

Change the implementation for each of these to match the documented behavior.

Change-Id: Ifccff9b7b03baaeffdc366d05f6286ba60e14934
Reviewed-on: https://go-review.googlesource.com/c/148317
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-08 02:34:04 +00:00
Joe Tsai
1795eb16a4 internal/impl: rename legacy_extension.go as legacy_extension_hack.go
The current logic in this file is temporary and will be removed.
Rename the file as legacy_extension_hack.go so that the future
legacy_extension.go file can contain the actual legacy code that cannot be
removed anytime in the near future.

Change-Id: I7edd9d682836379c4c97d18ea2c2a2e3b15db5a2
Reviewed-on: https://go-review.googlesource.com/c/147918
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-06 21:02:36 +00:00
Joe Tsai
f0ad886d73 reflect/prototype: implement NewGoExtension
Implement the constructor for protoreflect.ExtensionType.
The constructor is more complicated than NewGoEnum and NewGoMessage because
it is responsible for providing the wrappers to present *[]T as a
protoreflect.Vector.

There are no tests since we need the follow-up logic in internal/impl to actually
make use of extensions. A subsequent CL will add that logic and comprehensively
test extensions.

Change-Id: I2d7893de299fe40be2ccedd8f39a92c40c41e59a
Reviewed-on: https://go-review.googlesource.com/c/147578
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-06 20:55:45 +00:00
Joe Tsai
88bc5a7d99 internal/value: extract Vector and Map logic as separate package
The implementation of reflect/protoreflect.NewGoExtension needs to be able to
provide a constructor for wrapping *[]T as a protoreflect.Vector.
However, it cannot depend on internal/impl since impl also depends on prototype.
Extract the common logic of Vector creation into a separate package that
has no dependencies on either impl or prototype.

Change-Id: I9295fde9b8861de11af085c91d9dfa56047d1b1e
Reviewed-on: https://go-review.googlesource.com/c/147446
Reviewed-by: Herbie Ong <herbie@google.com>
2018-11-06 01:20:32 +00:00
Joe Tsai
ce6edd3c71 internal/impl: support message and enum fields
Dynamically generate functions for handling message and enum fields,
regardless of whether they are of the v1 or v2 forms.

If a v1 message is encountered, it is automatically wrapped such that it
implements the v2 interface.

Change-Id: I457bc5286892e8fc00a61da7062dd33058daafd5
Reviewed-on: https://go-review.googlesource.com/c/143837
Reviewed-by: Damien Neil <dneil@google.com>
2018-11-05 22:25:52 +00:00
Joe Tsai
05828dba44 internal/encoding/tag: centralize logic for protobuf struct tag serialization
The bespoke text-serialization of field descriptors in protoc-gen-go is also
used in the legacy implementation of protobuf reflection to derive a
protoreflect.FieldDescriptor from legacy messages and also to convert to/from
protoreflect.ExtensionDescriptor and protoV1.ExtensionDesc.

Centralize this logic in a single place:
* to avoid reimplementing the same logic in internal/impl
* to keep the marshal and unmarshal logic co-located

Change-Id: I634c5afbb9dc6eda91d6cb6b0e68dbd724cb1ccb
Reviewed-on: https://go-review.googlesource.com/c/146758
Reviewed-by: Herbie Ong <herbie@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
2018-11-05 20:12:56 +00:00
Joe Tsai
95b0290ea8 internal/impl: support legacy unknown extension fields
The unknown fields in legacy messages is split across the XXX_unrecognized
field and also the XXX_InternalExtensions field. Implement support for
wrapping both fields and presenting it as if it were a unified set of
unknown fields.

Change-Id: If274fae2b48962520edd8a640080b6eced747684
Reviewed-on: https://go-review.googlesource.com/c/146517
Reviewed-by: Damien Neil <dneil@google.com>
2018-11-01 18:28:27 +00:00
Damien Neil
bb1d557b23 cmd/protoc-gen-go: factor out oneof field naming
A oneof is represented by a single struct field of interface type.
Pull out the decision of what to name that field into a separate
function.

The function is trivial (return oneof.GoName), but factoring out the
field name like this makes it a bit easier to experiment with changes to
the oneof implementation in the future.

Change-Id: I1114b68c85cb6608852fa1c6bf4103ff58fd5de6
Reviewed-on: https://go-review.googlesource.com/c/146397
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
2018-10-31 20:40:31 +00:00
Joe Tsai
2d5a169f75 internal/impl: use linked-list for unknown field ordering
Unknown fields follow a policy where the latest field takes precedence when
it comes to the ordering. However, the current implementation is incorrect
as it uses a slice and simply swaps the current entry with the last entry.
While this ensures that the latest field seen remains last, it does not ensure
that the swapped out entry is second-to-last.

To provide the desired behavior, a linked-list is used.
For simplicity, we use the list package in the standard library even if it
is neither the most performant nor type safe.

Change-Id: I675145c61f6b5b624ed9e94bbe2251b5a71e2c48
Reviewed-on: https://go-review.googlesource.com/c/145241
Reviewed-by: Damien Neil <dneil@google.com>
2018-10-31 18:39:54 +00:00
Damien Neil
6238696abc cmd/protoc-gen-go: replicate v1 generator behavior for MessageSet extensions
Given:

  package foo
  extend proto2.bridge.MessageSet {
    optional Message message_set_extension = 100;
  }

Register the extension as a message set extension and give it the name
"foo.".

We really shouldn't do this in this case; the special-case treatment of
extensions to MessageSet is only for extensions nested in a parent
message. However, this is consistent with the behavior of the v1 generator.
Match that for now.

Change-Id: I919c409605a197904fd3227efc920192d484f431
Reviewed-on: https://go-review.googlesource.com/c/145957
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
2018-10-30 18:46:20 +00:00
Damien Neil
6b54131a89 cmd/protoc-gen-go: generate forwarding decls for ExtensionDescs
When publicly importing a package with extension definitions, generate
forwarding declarations for the "E_..." ExtensionDesc var:

    var E_ExtensionField = publicimport.E_ExtensionField

Change-Id: Ifd57c487c3a44f303c2c098a42ea249b219b734f
Reviewed-on: https://go-review.googlesource.com/c/145498
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
2018-10-29 17:01:50 +00:00
Damien Neil
40a08052f9 cmd/protoc-gen-go: don't import _ weak imports
Don't generate a blank import for unused weak imports.

Full support for weak imports would involve not importing the package at
all. This just avoids generating an import when we don't need one.

Change-Id: I7e8491f415dc8333a2837db5225256b959921be2
Reviewed-on: https://go-review.googlesource.com/c/145497
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
2018-10-29 16:16:32 +00:00
Damien Neil
a485fbd353 reflect/protoreflect: add FieldDescriptor.DefaultEnumValue method
Default values for enums are specified by name, not number. An enum
may contain multiple values with different names but the same number.
Representing the default as a protoreflect.Value containing an EnumNumber
can discard information.

Add a method returning the EnumValueDescriptor.

Change-Id: If8beee3f81d41c4f9af45423252603b86949c7a5
Reviewed-on: https://go-review.googlesource.com/c/145158
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
2018-10-29 15:59:23 +00:00
Joe Tsai
e2afdc27e7 internal/impl: support legacy unknown fields
Add wrapper data structures to get legacy XXX_unrecognized fields to support
the new protoreflect.UnknownFields interface. This is a challenge since the
field is a []byte, which does not give us much flexibility to work with
in terms of choice of data structures.

This implementation is relatively naive where every operation is O(n) since
it needs to strip through the entire []byte each time. The Range operation
operates slightly differently from ranging over Go maps since it presents a
stale version of RawFields should a mutation occur while ranging.
This distinction is unlikely to affect anyone in practice.

Change-Id: Ib3247cb827f9a0dd6c2192cd59830dca5eef8257
Reviewed-on: https://go-review.googlesource.com/c/144697
Reviewed-by: Damien Neil <dneil@google.com>
2018-10-26 19:55:21 +00:00
Joe Tsai
78f02a161f reflect/protoreflect: clarify Mutable semantics
The Mutable semantics are simpler than currently documented. In an older design
of the protobuf reflection API, it was intended that there could be a mutable
version of the scalar kinds. However, support for this has been dropped,
simplifying the documented semantics.

Change-Id: If66740ffa5da65a3f2c8cf46700e0c23393a16d7
Reviewed-on: https://go-review.googlesource.com/c/144857
Reviewed-by: Damien Neil <dneil@google.com>
2018-10-26 00:35:03 +00:00
Joe Tsai
620bc28bae reflect/protoreflect: clarify Range semantics
Restrict mutation operations during Range to only the current iteration key.
This simplifies the guarantees that any given implementation may need to provide.

While none of the range operations have a defined order, UnknownFields.Range
is special in that the iteration order is at least deterministic.
This exception occurs because there is no obviously correct way to re-order them
(since order of unknown fields can have semantic significance).

Change-Id: I35145e500dbc7c87be7270f0d886ef52e13d07d8
Reviewed-on: https://go-review.googlesource.com/c/144700
Reviewed-by: Damien Neil <dneil@google.com>
2018-10-25 23:23:31 +00:00
Damien Neil
44000a1bea cmd/protoc-gen-go: treat extensions fields as proto2 in some places
The v1 generator doesn't include a "proto3" tag on extension fields,
even when the field is defined in a proto3 file. Match that behavior for
consistency. We can probably change this later if we want to; it's
unlikely anyone is depending on this behavior.

The v1 generator uses pointer types for extension fields, even when the
field is defined in a proto3 file. (e.g., *FooEnum instead of FooEnum.)
Match this behavior. We can't change this without breaking compatibility
in the generated code.

Change-Id: I4072f3dd1c915bf9ab89f1d5198e0144cb4de20f
Reviewed-on: https://go-review.googlesource.com/c/144282
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
2018-10-24 19:46:45 +00:00
Joe Tsai
ad8ee05d0e reflect/prototype: make extensions use proto2 semantics for IsPacked
Extensions are normally thought of as a proto2 feature.
However, proto3 actually allows declarations of field extensions *only*
if they extend messages declared in descriptor.proto.

In such a situation it is not well defined whether the extension field
operates under proto2 or proto3 properties.

In some ways, such declarations are proto3-like.
For example, the declaration in the proto file still follows
proto3's syntactical grammar (e.g., no "optional" label required)
and proto3 semantics (e.g., default values are not allowed).

However, in other ways, such declarations are proto2-like.
For example, a repeated field of numeric scalars is not automatically packed.
This property is determined by the following test.

Compile the following proto file:

	syntax = "proto3";
	import "google/protobuf/descriptor.proto";
	extend google.protobuf.FieldOptions {
		repeated sint32 test_field = 20181023;
	}

then compile and run a C++ program with the following snippet:

	google::protobuf::FieldOptions m;
	m.AddExtension(test_field, 1);
	m.AddExtension(test_field, 2);
	m.AddExtension(test_field, 3);
	fstream output("out", ios::out | ios::trunc | ios::binary);
	m.SerializeToOstream(&output);

which produces an "out" file with the following contents:

	$ pbdump -sints 20181023 out
	Message{
		Tag{20181023, Varint}, Svarint(1),
		Tag{20181023, Varint}, Svarint(2),
		Tag{20181023, Varint}, Svarint(3),
	}

which is indicative that packed encoding was not used by default (proto2-like).
If we repeat the above experiment and explicit set "[packed = true]",
then packed encoding is used:

	$ pbdump -sints 20181023 out
	Message{
		Tag{20181023, Bytes}, LengthPrefix{Svarint(1), Svarint(2), Svarint(3)},
	}

Note that this change does not mean that field extensions are always proto2
since the experiment above does not conclusively prove that. Thus, the Syntax
on extensions derived from the descriptor protos may still report proto3.

The behavior of packed encoding with regards to proto3 says:

	In proto3, repeated fields of scalar numeric types use packed encoding by default.

One way to interpret this is:

	In proto3 (messages), repeated fields of scalar numeric types use packed encoding by default.

In which case packedness is a property of the message's syntax
rather than the field's syntax (if such a distinction exists).
Since only proto2 messages can be extended, we can safely assume that all
extension fields use proto2 semantics for IsPacked.

Change-Id: Iae595c6d88c6e252cae7552cae083bad42f2494a
Reviewed-on: https://go-review.googlesource.com/c/144278
Reviewed-by: Damien Neil <dneil@google.com>
2018-10-24 17:43:20 +00:00
Joe Tsai
be5348c905 internal/impl: setup scaffolding for unknown and extension fields
Setup scaffolding for implementing unknown and extension fields.
Add functions to MessageType to produce a protoreflect.KnownFields or
protoreflect.UnknownFields from a message pointer.

Within the implementation of known fields, delegate the logic to the underlying
extension fields (which also implements protoreflect.KnownFields) if the field
number is not found in the set of defined fields.

Change-Id: I2c35f4cdf1c7b58727ce6a582861ef18b8d69a61
Reviewed-on: https://go-review.googlesource.com/c/144280
Reviewed-by: Damien Neil <dneil@google.com>
2018-10-24 17:40:36 +00:00
Joe Tsai
2f68590cf0 reflect/prototype: use proto2 syntax for standalone extension fields
Without resolving the question of whether an extension field is always proto2
or sometimes proto3, just make it impossible to construct a standalone extension
field of the proto3 syntax.

By dropping the syntax field from the constructor, we can just assume that the
syntax is always proto2. There is no benefit for creating a proto3 standalone
extension, so there is no loss of functionality.

In the unlikely future where there needs to be distinction, we can add the field
back into the descriptor. The zero value of protoreflect.Syntax is invalid,
so we can determine if the user did not set that field.

Change-Id: Ie93fa55de96f29553fb04ff6649bbea79a144407
Reviewed-on: https://go-review.googlesource.com/c/144279
Reviewed-by: Damien Neil <dneil@google.com>
2018-10-24 17:35:49 +00:00
Damien Neil
204f1c0ad8 reflect/protoreflect: add Descriptor.Options method
Add a method to fetch descriptor options. Since options are proto
messages (e.g., google.protobuf.FieldOptions), and proto message
packages depend on the protoreflect package, returning the actual option
type would cause a dependency cycle. Instead, we return an interface
value which can be type asserted to the appropriate concrete type.

Add options support to the prototype package.

Some of the prototype constructors included fields (such as
Field.IsPacked) which represent information from the options
(such as google.protobuf.FieldOptions.packed). To avoid confusion about
the canonical source of information, drop these fields in favor of the
options.

Drop the unimplemented Descriptor.DescriptorOptionsProto.

Change-Id: I66579b6a7d10d99eb6977402a247306a78913e74
Reviewed-on: https://go-review.googlesource.com/c/144277
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
2018-10-23 23:44:11 +00:00
Joe Tsai
90fe996bd1 internal/impl: derive descriptors for legacy enums and messages
In order for the v2 rollout to be as seamless as possible, we need to support
the situation where a v2 message depends on some other generated v1 message that
may be stale and does not support the v2 API. In such a situation, there needs
to be some way to wrap a legacy message or enum in such a way that it satisfies
the v2 API.

This wrapping is comprised of two parts:
1) Deriving an enum or message descriptor
2) Providing an reflection implementation for messages

This CL addresses part 1 (while part 2 has already been partially implemented,
since the implementation applies to both v1 and v2).

To derive the enum and message descriptor we rely on a mixture of parsing the
raw descriptor proto and also introspection on the fields in the message.
Methods for obtaining the raw descriptor protos were added in February, 2016,
and so has not always been available. For that reason, we attempt to derive
as much information from the Go type as possible.

As part of this change, we modify prototype to be able to create multiple
standalone messages as a set. This is needed since cyclic dependencies is allowed
between messages within a single proto file.

Change-Id: I71aaf5f977faf9fba03c370b1ee17b3758ce60a6
Reviewed-on: https://go-review.googlesource.com/c/143539
Reviewed-by: Damien Neil <dneil@google.com>
2018-10-22 17:18:39 +00:00
Joe Tsai
bda671fa93 cmd/protoc-gen-go: re-escape default byte values
Historically, protoc-gen-go outputted the escaped form of bytes as provided by
protoc verbatim. This behavior is buggy, but nothing really uses this tag
since default values are properties of getters instead of serialization.
Rather than fixing it, just preserve prior behavior. Otherwise, logic depending
on the old legacy behavior will not be able to distinguish between the unescaped
or the escaped forms.

Furthermore, since protoc-gen-go historically copied the protoc output verbatim,
we will need to escape the default bytes in a way that is identical to the
CEscape function from strutil.cc of the protoc source code.

Change-Id: I0ab55e220ae430dd123ad050406e285788f6cb40
Reviewed-on: https://go-review.googlesource.com/c/143543
Reviewed-by: Damien Neil <dneil@google.com>
2018-10-22 17:14:19 +00:00
Joe Tsai
2c870bb5cc internal/impl: implement oneof fields
Dynamically generate functions for handling individual fields within an oneof.
This implementation uses Go reflection to interact with the currently generated
approach, which uses an interface that can only be set by a limited set of
wrapper structs.

Change-Id: Ic848df922d6547411a15c4a20bfbbcae362da5c0
Reviewed-on: https://go-review.googlesource.com/c/142895
Reviewed-by: Damien Neil <dneil@google.com>
2018-10-17 22:20:50 +00:00
Damien Neil
ba1159f426 protogen: move comment generation into protogen
Most plugins need to copy comments from .proto source files into the
generated code. Move this functionality into protogen to avoid
duplicating it everywhere.

Change-Id: I48a96ba794192e7ddc00281342afd4805ef6fe0f
Reviewed-on: https://go-review.googlesource.com/c/142890
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
2018-10-17 21:03:49 +00:00
Joe Tsai
3903b218df reflect/protoreflect: remove List method
Remove List from KnownFields, UnknownFields, ExtensionFieldTypes, and Map.

Rationale:
* Each of those interfaces already have a Range method, which provides
a superset of the functionality of List. Furthermore, Range is more expressive
as it allows you to terminate iteration and provides both keys and values.
* List must always allocate a slice and populates it.
* Range is allocation free in some cases. For example, if you simply wanted to
iterate over all the populated fields to clear them, there is no need for a
closure, so a static version of the function can be directly referenced
(i.e., there is no need to create a stub function header that references the
closed-over variables).
* In the cases where a closure is needed, the allocation cost is O(1) since
there are a finite number of variables being closed over.
* In highly performance sensitive cases, the closured function could close over
a struct, such that the function and struct are stored in a sync.Pool when not
in use. For example:

	type MapLister struct {
		Entries []struct{K MapKey; V Value}
		f       func(MapKey, Value) true
	}
	func (m *MapLister) Ranger() func(MapKey, Value) bool {
		if m.f != nil {
			m.f = func(k MapKey, v Value) bool {
				m.Entries = append(m.Entries, ...)
				return true
			}
		}
		m.Entries = m.Entries[:0]
		return m.f
	}

The main benefit of List is the ease of use:

	for _, num := range knownFields.List() {
		...
	}

as opposed to:

	knownFields.Range(func(n FieldNumber, v Value) bool {
		...
		return true
	})

However, this is a marginal benefit.
Thus, remove List as it mostly inferior to Range.

Change-Id: I25586c6ea07a4706072ba06b1cf25cb6efb5e8a7
Reviewed-on: https://go-review.googlesource.com/c/142888
Reviewed-by: Damien Neil <dneil@google.com>
2018-10-17 19:30:39 +00:00
Joe Tsai
bbfaeb77e5 internal/impl: implement Map fields
Generate functions for wrapping map[K]V to implement protoreflect.Map.
This implementation uses Go reflection instead to provide a single implementation
that can handle all Go map types.

Change-Id: Idcb8069ef836614a88e5df12ef7c5044e8aa3dea
Reviewed-on: https://go-review.googlesource.com/c/142778
Reviewed-by: Damien Neil <dneil@google.com>
2018-10-17 17:45:34 +00:00