Various protoreflect methods can return an "empty, read-only" message,
list, or map value. Provide a method to test if a value is one of these.
Fixesgolang/protobuf#966
Change-Id: I793d8426d6e2201755983c06f024412a7e09bc4c
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/209018
Reviewed-by: Joe Tsai <joetsai@google.com>
Remove repeated extension fields from the set of nullable fields,
so that Has reports false and Range does not visit a a zero-length
repeated extension field.
This corrects a fuzzer-detected case where unmarshaling and remarshaling
a wire-format message could result in a semantic change. For a repeated
extension field in non-packed encoding, unmarshaling a packed
representation of the field would result in a message which Has the
extension. Remarshaling it would discard the the field.
Fixesgolang.org/protobuf#975
Change-Id: Ie836559c93d218db5b5201742a3b8ebbaacf54ed
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/204897
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Reviewed-by: Joe Tsai <joetsai@google.com>
These methods are difficult or impossible to use correctly; types
created by the dynamicpb package, for example, all have the same GoType.
Fixesgolang/protobuf#938
Change-Id: I33d4ef381579ff18569b11df501d0ba7f38a6b5c
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/199060
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Rather than using the <unknown:%d> syntax for GoString,
emit something similar to TypeName(%d),
which is functionally equivalent to casting the integer
to the specified type.
Change-Id: Ibf4bd680d1672fcaba9022fb6bd03bbfe249b8b7
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/191580
Reviewed-by: Herbie Ong <herbie@google.com>
Add a way to typecheck a Value or interface{} without converting it to
the other form. This permits implementations which store field values as
a Value (such as dynamicpb, or (soon) extensions in generated messages)
to validate inputs without an unnecessary conversion.
Fixesgolang/protobuf#905
Change-Id: I1b78612b22ae832efbb55f81ae420871729e3a02
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/192457
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Descriptor methods generally return a Descriptor with no Go type
information. ExtensionType's Descriptor is an exception, returning an
ExtensionTypeDescriptor containing both the proto descriptor and a
reference back to the ExtensionType. The pure descriptor is accessed
by xt.Descriptor().Descriptor().
Rename ExtensionType's Descriptor method to TypeDescriptor to make it
clear that it behaves a bit differently.
Change 1/2: Add the TypeDescriptor method and deprecate Descriptor.
Change-Id: I1806095044d35a474d60f94d2a28bdf528f12238
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/192139
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Passing a non-pointer type to protoreflect.NewValue causes an
unnecessary allocation in order to store the value in an interface{}.
While this allocation could be avoided by a smarter compiler, no such
compiler exists today.
Add functions for creating new values of a specific type, avoiding the
allocation. (And also adding a small amount of type safety, although
this is unlikely to be important.)
Update the proto and internal/impl packages to use these functions.
Change-Id: Ic733de22ddf19c530189166c853348e1b54b7391
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/191457
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
There are many types in this package, which can get very confusing how
they all relate to each other. Add some Unicode box art to show the
relationships between XType, XDescriptor, and X.
Change-Id: I935e645907270cdbb70c561e6cb394078366f861
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/190379
Reviewed-by: Damien Neil <dneil@google.com>
Change protoiface.ExtensionDescV1 to implement protoreflect.ExtensionType.
ExtensionDescV1's Name field conflicts with the Descriptor Name method,
so change the protoreflect.{Message,Enum,Extension}Type types to no
longer implement the corresponding Descriptor interface. This also leads
to a clearer distinction between the two types.
Introduce a protoreflect.ExtensionTypeDescriptor type which bridges
between ExtensionType and ExtensionDescriptor.
Add extension accessor functions to the proto package:
proto.{Has,Clear,Get,Set}Extension. These functions take a
protoreflect.ExtensionType parameter, which allows writing the
same function call using either the old or new API:
proto.GetExtension(message, somepb.E_ExtensionFoo)
Fixesgolang/protobuf#908
Change-Id: Ibc65d12a46666297849114fd3aefbc4a597d9f08
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/189199
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
We occasionally need to work with immutable, empty lists, maps, and
messages. Notably, Message.Get on an empty repeated field will return a
"frozen" empty value.
Move handling of these immutable, zero-length composites into Converter,
to unify the behavior of regular and extension fields.
Add a Zero method to Converter, MessageType, and ExtensionType, to
provide a consistent way to get an empty, frozen value of a composite
type. Adding this method to the public {Message,Extension}Type
interfaces does increase our API surface, but lets us (for example)
cleanly represent an empty map as a nil map rather than a non-nil
one wrapped in a frozenMap type.
Drop the frozen{List,Map,Message} types as no longer necessary.
(These types did have support for creating a read-only view of a
non-empty value, but we are not currently using that feature.)
Change-Id: Ia76f149d591da07b40ce75b7404a7ab8a60cb9d8
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/189339
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Add methods to protoreflect.{Message,List,Map} to constrict values
assignable to a message field, list element, or map value. These
methods return the default value for scalar fields, the zero value for
scalar list elements and map values, and an empty, mutable value for
messages, lists, and maps.
Deprecate the NewMessage methods on these types, which are superseded.
Updates golang/protobuf#879
Change-Id: I0f064f60c89a239330ccea81523f559f14fd2c4f
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/188997
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
This adds minimal support for preserving the source context information.
Change-Id: I4b3cac9690b7469ecb4e5434251a809be4d7894c
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/183157
Reviewed-by: Damien Neil <dneil@google.com>
CL/174938 removed these methods in favor of a method that returned
only the descriptors. This CL adds back in the Type methods alongside
the Descriptor methods.
In a vast majority of protobuf usages, only the descriptor information
is needed. However, there is a small percentage that legitimately needs
the Go type information. We should provide both, but document that the
descriptor-only information is preferred.
Change-Id: Ia0a098997fb1bd009994940ae8ea5257ccd87cae
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/184578
Reviewed-by: Damien Neil <dneil@google.com>
The protoreflect.Descriptor.Options method is currently documented as
returning a reference to the options, where the user must not mutate
the returned message. This changes internal/filedesc to avoid returning
a copy of the options by caching the first unmarshal.
See golang/protobuf#877
Change-Id: I15701d33fbda7535b21b2add72628b02992c373f
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/185197
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Len looks like it should be O(1), but the need to check for
non-zero-length repeated fields makes it at minimum O(n) where n is
the number of repeated fields. In practice, it's O(n) where n is the
number of fields altogether.
The Len function is not especially useful, easily duplicated with Range
and a counter, and can be surprisingly inefficient. Drop it.
Change-Id: I24b27433217e131e842bd18dd58475bcdf62ef97
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/183678
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Preserving the unknown enum in the String method helps errors
produced by reflect/protodesc be more informative.
Change-Id: I8efb09cb3c744bf4483b310053df7686da540387
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/183699
Reviewed-by: Damien Neil <dneil@google.com>
The internal/fileinit package is split apart into two packages:
* internal/filedesc constructs descriptors from the raw proto.
It is very similar to the previous internal/fileinit package.
* internal/filetype wraps descriptors with Go type information
Overview:
* The internal/fileinit package will be deleted in a future CL.
It is kept around since the v1 repo currently depends on it.
* The internal/prototype package is deleted. All former usages of it
are now using internal/filedesc instead. Most significantly,
the reflect/protodesc package was almost entirely re-written.
* The internal/impl package drops support for messages that do not
have a Descriptor method (pre-2016). This removes a significant amount
of technical debt.
filedesc.Builder to parse raw descriptors.
* The internal/encoding/defval package now handles enum values by name.
Change-Id: I3957bcc8588a70470fd6c7de1122216b80615ab7
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/182360
Reviewed-by: Damien Neil <dneil@google.com>
This is a breaking change in light of new methods added in CL/175458.
This removes:
Message.KnownFields: equivalent functionality have been hoisted up
to the Message interface itself.
Message.UnknownFields: equivalent functionality is via
the Message.{Set,Get}Unknown methods.
Change-Id: Ia08b26894d2b45033a6ad6616258ff0fb9f8b7a4
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/182597
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
This is a breaking change in light of new methods added in CL/174918.
This removes:
Enum.Type: replacement is Descriptor
Message.Type: replacement is Descriptor and New
Change-Id: Iaa5328795407c8401ef14ed038bd5ace19d8e03b
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/174938
Reviewed-by: Damien Neil <dneil@google.com>
This is a breaking change in light of new methods added in CL/176977.
This removes:
FieldDescriptor.Oneof: replacement is ContainingOneof
FieldDescriptor.Extendee: replacement is IsExtension and ContainingMessage
Change-Id: I82008e46fb3b80de8e8a0ac42afc54e8c4b67411
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/176942
Reviewed-by: Damien Neil <dneil@google.com>
This is a breaking change.
The equivalent replacement logic is to trivially check whether the
parent descriptor is not nil.
Change-Id: I5c89c1d9f29f9e6f721bbfbcf7774188d8f0086a
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/175987
Reviewed-by: Damien Neil <dneil@google.com>
Added API:
Message.Len
Message.Range
Message.Has
Message.Clear
Message.Get
Message.Set
Message.Mutable
Message.NewMessage
Message.WhichOneof
Message.GetUnknown
Message.SetUnknown
Deprecated API (to be removed in subsequent CL):
Message.KnownFields
Message.UnknownFields
The primary difference with the new API is that the top-level
Message methods are keyed by FieldDescriptor rather than FieldNumber
with the following semantics:
* For known fields, the FieldDescriptor must exactly match the
field descriptor known by the message.
* For extension fields, the FieldDescriptor must implement ExtensionType,
where ContainingMessage.FullName matches the message name, and
the field number is within the message's extension range.
When setting an extension field, it automatically stores
the extension type information.
* Extension fields are always considered nullable,
implying that repeated extension fields are nullable.
That is, you can distinguish between a unpopulated list and an empty list.
* Message.Get always returns a valid Value even if unpopulated.
The behavior is already well-defined for scalars, but for unpopulated
composite types, it now returns an empty read-only version of it.
Change-Id: Ia120630b4db221aeaaf743d0f64160e1a61a0f61
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/175458
Reviewed-by: Damien Neil <dneil@google.com>
Temporarily remove go.mod, since we can't generate an accurate one until
the corresponding v1 change is submitted.
Change-Id: I1e1ad97f2b455e33f61ffaeb8676289795e47e72
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/177000
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Added API:
FieldDescriptor.IsExtension
FieldDescriptor.IsList
FieldDescriptor.MapKey
FieldDescriptor.MapValue
FieldDescriptor.ContainingOneof
FieldDescriptor.ContainingMessage
Deprecated API (to be removed in subsequent CL):
FieldDescriptor.Oneof
FieldDescriptor.Extendee
These methods help cleanup several common usage patterns.
Change-Id: I9a3ffabc2edb2173c536509b22f330f98bba7cf3
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/176977
Reviewed-by: Damien Neil <dneil@google.com>
Querying for the parent file that contains a descriptor declaration
is a common enough operation to warrant its own first-class method.
Change-Id: I2f41e5126a5b465df23897904a6513dd3ed8dd92
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/176777
Reviewed-by: Damien Neil <dneil@google.com>
Added methods:
Enum.Descriptor
Message.Descriptor
EnumType.Descriptor
MessageType.Descriptor
ExtensionType.Descriptor
Message.New
All functionality is switched over to use those methods instead of
implicitly relying on the fact that {Enum,Message}Type implicitly
implement the associated descriptor interface.
This CL does not yet remove {Enum,Message}.Type or prevent
{Enum,Message,Extension}Type from implementating a descriptor.
That is a subsequent CL.
The Message.New method is also added to replace functionality
that will be lost when the Type methods are removed.
Change-Id: I7fefde1673bbd40bfdac489aca05cec9a6c98eb1
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/174918
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Herbie Ong <herbie@google.com>
CL/172238 added equivalent methods without the Type suffix,
while keeping the old methods.
CL/172582 updates the v1 codebase to use the new methods.
This CL removes the methods with the Type suffix.
Change-Id: Iaaaa4fff11cac1694735657db2e5fd7cadc90afe
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/173138
Reviewed-by: Herbie Ong <herbie@google.com>
The protobuf type system uses the word "descriptor" instead of "type".
We should avoid the "type" verbage when we aren't talking about Go types.
The old names are temporarily kept around for compatibility reasons.
Change-Id: Icc99c913528ead011f7a74aa8399d9c5ec6dc56e
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/172238
Reviewed-by: Herbie Ong <herbie@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
Drop the protoreflect.FileDescriptor.DescriptorByName method.
Descriptor lookup will always happen through a protoregistry.Files, which
is more generally useful (it's rare that you want to find a descriptor in a
specific file, as opposed to a package which may be composed of multiple files).
Split protoregistry.Files descriptor lookup into individual per-type functions
(enum, message, extension, service), matching the preg.Types API.
Drop the ability to look up enum values, message fields, and service methods
for now. This can be easily added later if needed, and is trivial to implement
in user code. (e.g., look up the service and then consult sd.Methods.ByName().)
Change-Id: I2b3d8ef888921a8464ba1434eddab20c7d3a458e
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/172118
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Changes:
* Remove protoreflect.OptionsMessage and use protoreflect.ProtoMessage
now that the generated options natively implement reflection.
* Make registration of concrete option types the responsibility of
internal/fileinit since the init logic of descriptor.pb.go uses that.
* Remove equivalent logic in protoc-gen-go to special-case descriptor.
Change-Id: Id814651fafa4d888ff4532d59c6a4f9b68145157
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/171465
Reviewed-by: Damien Neil <dneil@google.com>
Add a method that provides efficiently querying for which member field
in a oneof is actually set. This is useful when dealing with oneofs
with many member fields.
Change-Id: I918b566c432f8bdd24dcecbb5501d231ffefef29
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/170580
Reviewed-by: Damien Neil <dneil@google.com>
This change preserves consistency with CL/157077,
where New returns a value closer to the reflective type.
Change-Id: I85bfdae24e1ce1a10c3c7b939420fa1043bff743
Reviewed-on: https://go-review.googlesource.com/c/157078
Reviewed-by: Damien Neil <dneil@google.com>
Rephrase the documentation in terms of usage of this package: Lead with
the description of what this package contains and provide guidance on where
to get a descriptor or value interface.
Change-Id: I40a43cd59d1fbca6c60eff1c3afe50ff4a15b82f
Reviewed-on: https://go-review.googlesource.com/c/157217
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Most usages of New actually prefer to interact with the reflective view
rather than the native Go type. Thus, change New to return that instead.
This parallels reflect.New, which returns the reflective view
(i.e., reflect.Value) instead of native type (i.e., interface{}).
We make the equivalent change to KnownFields.NewMessage, List.NewMessage,
and Map.NewMessage for consistency.
Since this is a subtle change where the type system will not always
catch the changed type, this change was made by both changing the type
and renaming the function to NewXXX and manually looking at every usage
of the the function to ensure that the usage correctly operates
on either the native Go type or the reflective view of the type.
After the entire codebase was cleaned up, a rename was performed to convert
NewXXX back to New.
Change-Id: I153fef627b4bf0a427e4039ce0aaec52e20c7950
Reviewed-on: https://go-review.googlesource.com/c/157077
Reviewed-by: Damien Neil <dneil@google.com>
Drop the protoreflect.ProtoEnum type (containing a single method
returning a protoreflect.Enum) and make generated enum types
directly implement protoreflect.Enum instead.
Messages have a two-level type split (ProtoMessage and Message) to
minimize conflicts between reflection methods and field names. Enums
need no such split, since enums do not have fields and therefore have
no source of conflicts.
Change-Id: I2b6222e9404253e6bfef2217859e1b760ffcd29b
Reviewed-on: https://go-review.googlesource.com/c/156902
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Reviewed-by: Damien Neil <dneil@google.com>
The purego tag (see https://golang.org/issue/23172) is a community agreed
upon signal that a given build environment does not support unsafe.
The appengine environment is supposed to respect this tag, but does not
properly do so. Add this tag back in until they fix their environment.
Change-Id: I9a70062be4339c2e1a93cac31d387698c561b8aa
Reviewed-on: https://go-review.googlesource.com/c/154743
Reviewed-by: Damien Neil <dneil@google.com>
Introduce a protoreflect.OptionsMessage interface type to represent
options messages. The protoreflect package can't deal with concrete
options types, to avoid dependency cycles; OptionsMessage serves both
as documentation and a single point to define the constraints we apply
to options.
Change the constraints on options from ProtoMessage to interface{} to
permit use of option message types which only implement the v1
proto.Message interface.
This still leaves a requirement in the internal/legacy package that
options implement protoreflect.ProtoMessage, since that package now uses
the v2 Unmarshal.
Change-Id: I547518ab2c3b90c3911ef641b05b169d50a4b33a
Reviewed-on: https://go-review.googlesource.com/c/154877
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
The DescriptorProto method was originally intended to return a raw descriptor.
However, that functionality will be responsibility of the protodesc package
in the near future.
Also document that any callers of Options must import the descriptor package.
This is reasonable since any usage of that method will almost always be of
the form:
fd.Options().(*descriptorpb.FieldOptions)
Change-Id: I1085f02305faef8dd724e0cb3ad45ac12bd5df0a
Reviewed-on: https://go-review.googlesource.com/c/153497
Reviewed-by: Damien Neil <dneil@google.com>
Remove the Mutable methods from KnownFields, List, and Map, replacing
them with methods which return a new, empty message value without adding
that value to the collection.
The new API is simpler, since it clearly applies only to message values,
and more orthogonal, since it provides a way to create a value without
mutating the collection. This latter point is particularly useful in
map deserialization, where the key may be unknown at the time the value
is deserialized.
Drop the Mutable interface, since it is no longer necessary.
Change-Id: Ic5f3d06a2aa331a5d5cd2b4e670a3dba4a74f77c
Reviewed-on: https://go-review.googlesource.com/c/153278
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
These properties of descriptors are currently missing and makes it impossible
to convert a FileDescriptorProto into one of the structured Go representations
and convert it back to a proto message without loss of information.
Furthermore, ReservedRanges and ReservedNames has semantic importance
to text serialization.
Change-Id: Ic33c30020ad51912b143156b95f47a4fb8da3503
Reviewed-on: https://go-review.googlesource.com/c/153019
Reviewed-by: Damien Neil <dneil@google.com>
Considerable thought was given to whether a seperate ExtensionRanges interface
should be made that encapsulates FieldNumbers with an Options method.
However, I decided against this design for the following reasons:
* Extension ranges share syntax with reserved numbers and fields.
Why is extension ranges so special that it can have options, while the other
two currently do not? How do we know that those other two won't grow options
in the future? If they do, then those APIs can be expanded in the same way as
how extension range options is being expanded here today.
* Extension range options stand out like a sore thumb compared to the other
eight options. The other options correspond with a named declaration and have
a full protobuf name that they are associated with. Extension range options
is the only options that is not correlated with a full name.
* Extension range options are an extremely rarely used feature and
it seems unfortunate complicating the common case with additional structure.
Change-Id: Ib284a0b798c57dc264febe304692eee5b9c8e91b
Reviewed-on: https://go-review.googlesource.com/c/153018
Reviewed-by: Damien Neil <dneil@google.com>
Implement support in protoc-gen-go for generating messages and enums
that satisfy the v2 protobuf reflection interfaces. Specifically, the following
are added:
* top-level variable representing the file descriptor
* ProtoReflect method on enums (to implement protoV2.Enum)
* ProtoReflect method on messages (to implement protoV2.Message)
The following are not supported yet:
* resolving transitive dependencies for file imports
* Extension descriptors
* Service descriptors
The implementation approach creates a single array for all the message and enum
declarations and references sections of that array to complete dependencies.
Since protobuf declarations can form a graph (a message may depend on itself),
it is difficult to construct a graph as a single literal. One way is to use
placeholder descriptors, but that is not efficient as it requires encoding
the full name of each dependent enum and message and then later resolving it;
thus, both expanding the binary size and also increasing initialization cost.
Instead, we add a prototype.{Enum,Message}.Reference method to obtain a
descriptor reference for the purposes for satisfying dependencies.
As such, nested declarations and dependencies are populated in an init function.
Other changes to support the implementation:
* Added a protoimpl package to expose the MessageType type and also the
MessageTypeOf and EnumTypeOf helper functions.
* Added a protogen.File.GoIdent field to provide a suggested variable name
for the file descriptor.
* Added prototype.{Enum,Message}.Reference that provides a descriptor reference
for the purposes for satisfying cyclic dependencies.
* Added protoreflect.{Syntax,Cardinality,Kind}.GoString to obtain a Go source
identifier that represents the given constant.
Change-Id: I9455764882dee6ad10f251901e7d419091e8bf1d
Reviewed-on: https://go-review.googlesource.com/c/150074
Reviewed-by: Damien Neil <dneil@google.com>
In order to generate descriptor.proto, the generated code would want to depend
on the prototype package to construct the reflection data structures.
However, this is a problem since descriptor itself is one of the dependencies
for prototype. To break this dependency, we do the following:
* Avoid using concrete *descriptorpb.XOptions messages in the public API, and
instead just use protoreflect.ProtoMessage. We do lose some type safety here
as a result.
* Use protobuf reflection to interpret the Options message.
* Split out NewFileFromDescriptorProto into a separate protodesc package since
constructing protobuf reflection from the descriptor proto obviously depends
on the descriptor protos themselves.
As part of this CL, we check in a pre-generated version of descriptor and plugin
that supports protobuf reflection natively and switchover all usages of those
protos to the new definitions. These files were generated by protoc-gen-go
from CL/150074, but hand-modified to remove dependencies on the v1 proto runtime.
Change-Id: I81e03c42eeab480b03764e2fcbe1aae0e058fc57
Reviewed-on: https://go-review.googlesource.com/c/152020
Reviewed-by: Damien Neil <dneil@google.com>
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>
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>
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>
