diff --git a/src/internal/cm/CHANGELOG.md b/src/internal/cm/CHANGELOG.md new file mode 100644 index 000000000..35efaf2f5 --- /dev/null +++ b/src/internal/cm/CHANGELOG.md @@ -0,0 +1,23 @@ +# Changelog + +The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html). + +## [v0.2.0] — 2025-03-15 + +### Added + +- Initial support for Component Model [async](https://github.com/WebAssembly/component-model/blob/main/design/mvp/Async.md) types `stream`, `future`, and `error-context`. +- Initial support for JSON serialization of WIT `list`, `enum`, and `record` types. +- Added `cm.CaseUnmarshaler` helper for text and JSON unmarshaling of `enum` and `variant` types. + +### Changed + +- Breaking: package `cm`: removed `bool` from `Discriminant` type constraint. It was not used by code generation. + +## [v0.1.0] — 2024-12-14 + +Initial version, extracted into module [`go.bytecodealliance.org/cm`](https://pkg.go.dev/go.bytecodealliance.org/cm). + +[Unreleased]: +[v0.2.0]: +[v0.1.0]: diff --git a/src/internal/cm/LICENSE b/src/internal/cm/LICENSE new file mode 100644 index 000000000..f9d81955f --- /dev/null +++ b/src/internal/cm/LICENSE @@ -0,0 +1,220 @@ + + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + + TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + + 1. Definitions. + + "License" shall mean the terms and conditions for use, reproduction, + and distribution as defined by Sections 1 through 9 of this document. + + "Licensor" shall mean the copyright owner or entity authorized by + the copyright owner that is granting the License. + + "Legal Entity" shall mean the union of the acting entity and all + other entities that control, are controlled by, or are under common + control with that entity. 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These are intended for use by generated [Component Model](https://github.com/WebAssembly/component-model/blob/main/design/mvp/Explainer.md#type-definitions) bindings, where the caller converts to a Go equivalent. It attempts to map WIT semantics to their equivalent in Go where possible. + +### Note on Memory Safety + +Package `cm` and generated bindings from `wit-bindgen-go` may have compatibility issues with the Go garbage collector, as they directly represent `variant` and `result` types as tagged unions where a pointer shape may be occupied by a non-pointer value. The GC may detect and throw an error if it detects a non-pointer value in an area it expects to see a pointer. This is an area of active development. + +## License + +This project is licensed under the Apache 2.0 license with the LLVM exception. See [LICENSE](../LICENSE) for more details. diff --git a/src/internal/cm/RELEASE.md b/src/internal/cm/RELEASE.md new file mode 100644 index 000000000..5a6283a60 --- /dev/null +++ b/src/internal/cm/RELEASE.md @@ -0,0 +1,34 @@ +# Release + +This document describes the steps to release a new version of module `go.bytecodealliance.org/cm`. + +## 1. Update [CHANGELOG.md](./CHANGELOG.md) + +1. Add the latest changes to [CHANGELOG.md](./CHANGELOG.md). +1. Rename the Unreleased section to reflect the new version number. + 1. Update the links to new version tag in the footer of CHANGELOG.md +1. Add today’s date (YYYY-MM-DD) after an em dash (—). +1. Submit a [GitHub Pull Request](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/about-pull-requests) with these updates. + +## 2. Create a new release + +Once the PR is merged, tag the new version in Git and push the tag to GitHub. + +**Note:** the tag **must** start with the prefix `cm/` in order to correctly tag this module. + +For example, to tag version `cm/v0.2.0`: + +```console +git tag cm/v0.2.0 +git push origin cm/v0.2.0 +``` + +## 3. Update the root module + +Once the tag is pushed, you can update the root module to depend on the newly created version of package `cm` by running the following: + +```console +go get -u go.bytecodealliance.org/cm@latest +``` + +Then follow the instructions in [RELEASE.md](../RELEASE.md) to release a new version of the root module. diff --git a/src/internal/cm/case.go b/src/internal/cm/case.go new file mode 100644 index 000000000..65ade4949 --- /dev/null +++ b/src/internal/cm/case.go @@ -0,0 +1,51 @@ +package cm + +import "errors" + +// CaseUnmarshaler returns an function that can unmarshal text into +// [variant] or [enum] case T. +// +// [enum]: https://component-model.bytecodealliance.org/design/wit.html#enums +// [variant]: https://component-model.bytecodealliance.org/design/wit.html#variants +func CaseUnmarshaler[T ~uint8 | ~uint16 | ~uint32](cases []string) func(v *T, text []byte) error { + if len(cases) <= linearScanThreshold { + return func(v *T, text []byte) error { + if len(text) == 0 { + return errEmpty + } + s := string(text) + for i := 0; i < len(cases); i++ { + if cases[i] == s { + *v = T(i) + return nil + } + } + return errNoMatchingCase + } + } + + m := make(map[string]T, len(cases)) + for i, v := range cases { + m[v] = T(i) + } + + return func(v *T, text []byte) error { + if len(text) == 0 { + return errEmpty + } + s := string(text) + c, ok := m[s] + if !ok { + return errNoMatchingCase + } + *v = c + return nil + } +} + +const linearScanThreshold = 16 + +var ( + errEmpty = errors.New("empty text") + errNoMatchingCase = errors.New("no matching case") +) diff --git a/src/internal/cm/docs.go b/src/internal/cm/docs.go index 5fc48fb75..5522cf942 100644 --- a/src/internal/cm/docs.go +++ b/src/internal/cm/docs.go @@ -1,4 +1,4 @@ -// Package cm contains types and functions for interfacing with the WebAssembly Component Model. +// Package cm provides types and functions for interfacing with the WebAssembly Component Model. // // The types in this package (such as [List], [Option], [Result], and [Variant]) are designed to match the memory layout // of [Component Model] types as specified in the [Canonical ABI]. diff --git a/src/internal/cm/empty.s b/src/internal/cm/empty.s new file mode 100644 index 000000000..5444f2006 --- /dev/null +++ b/src/internal/cm/empty.s @@ -0,0 +1,3 @@ +// This file exists for testing this package without WebAssembly, +// allowing empty function bodies with a //go:wasmimport directive. +// See https://pkg.go.dev/cmd/compile for more information. diff --git a/src/internal/cm/error.go b/src/internal/cm/error.go new file mode 100644 index 000000000..857d5ce7c --- /dev/null +++ b/src/internal/cm/error.go @@ -0,0 +1,40 @@ +package cm + +import "unsafe" + +// ErrorContext represents the Component Model [error-context] type, +// an immutable, non-deterministic, host-defined value meant to aid in debugging. +// +// [error-context]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/Explainer.md#error-context-type +type ErrorContext struct { + _ HostLayout + errorContext +} + +type errorContext uint32 + +// Error implements the [error] interface. It returns the debug message associated with err. +func (err errorContext) Error() string { + return err.DebugMessage() +} + +// String implements [fmt.Stringer]. +func (err errorContext) String() string { + return err.DebugMessage() +} + +// DebugMessage represents the Canonical ABI [error-context.debug-message] function. +// +// [error-context.debug-message]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/Explainer.md#error-contextdebug-message +func (err errorContext) DebugMessage() string { + var s string + wasmimport_errorContextDebugMessage(err, unsafe.Pointer(&s)) + return s +} + +// Drop represents the Canonical ABI [error-context.drop] function. +// +// [error-context.drop]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/Explainer.md#error-contextdrop +func (err errorContext) Drop() { + wasmimport_errorContextDrop(err) +} diff --git a/src/internal/cm/error.wasm.go b/src/internal/cm/error.wasm.go new file mode 100644 index 000000000..112eb6d81 --- /dev/null +++ b/src/internal/cm/error.wasm.go @@ -0,0 +1,13 @@ +package cm + +import "unsafe" + +// msg uses unsafe.Pointer for compatibility with go1.23 and lower. +// +//go:wasmimport canon error-context.debug-message +//go:noescape +func wasmimport_errorContextDebugMessage(err errorContext, msg unsafe.Pointer) + +//go:wasmimport canon error-context.drop +//go:noescape +func wasmimport_errorContextDrop(err errorContext) diff --git a/src/internal/cm/future.go b/src/internal/cm/future.go new file mode 100644 index 000000000..e82183f65 --- /dev/null +++ b/src/internal/cm/future.go @@ -0,0 +1,15 @@ +package cm + +// Future represents the Component Model [future] type. +// A future is a special case of stream. In non-error cases, +// a future delivers exactly one value before being automatically closed. +// +// [future]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/Explainer.md#asynchronous-value-types +type Future[T any] struct { + _ HostLayout + future[T] +} + +type future[T any] uint32 + +// TODO: implement methods on type future diff --git a/src/internal/cm/go.mod b/src/internal/cm/go.mod new file mode 100644 index 000000000..f8e24af71 --- /dev/null +++ b/src/internal/cm/go.mod @@ -0,0 +1,3 @@ +module go.bytecodealliance.org/cm + +go 1.23.0 diff --git a/src/internal/cm/list.go b/src/internal/cm/list.go index 5c896d044..0a171dbd3 100644 --- a/src/internal/cm/list.go +++ b/src/internal/cm/list.go @@ -1,6 +1,10 @@ package cm -import "unsafe" +import ( + "bytes" + "encoding/json" + "unsafe" +) // List represents a Component Model list. // The binary representation of list is similar to a Go slice minus the cap field. @@ -58,3 +62,57 @@ func (l list[T]) Data() *T { func (l list[T]) Len() uintptr { return l.len } + +// MarshalJSON implements json.Marshaler. +func (l list[T]) MarshalJSON() ([]byte, error) { + if l.len == 0 { + return []byte("[]"), nil + } + + s := l.Slice() + var zero T + if unsafe.Sizeof(zero) == 1 { + // The default Go json.Encoder will marshal []byte as base64. + // We override that behavior so all int types have the same serialization format. + // []uint8{1,2,3} -> [1,2,3] + // []uint32{1,2,3} -> [1,2,3] + return json.Marshal(sliceOf(s)) + } + return json.Marshal(s) +} + +type slice[T any] []entry[T] + +func sliceOf[S ~[]E, E any](s S) slice[E] { + return *(*slice[E])(unsafe.Pointer(&s)) +} + +type entry[T any] [1]T + +func (v entry[T]) MarshalJSON() ([]byte, error) { + return json.Marshal(v[0]) +} + +// UnmarshalJSON implements json.Unmarshaler. +func (l *list[T]) UnmarshalJSON(data []byte) error { + if bytes.Equal(data, nullLiteral) { + return nil + } + + var s []T + err := json.Unmarshal(data, &s) + if err != nil { + return err + } + + l.data = unsafe.SliceData([]T(s)) + l.len = uintptr(len(s)) + + return nil +} + +// nullLiteral is the JSON representation of a null literal. +// By convention, to approximate the behavior of Unmarshal itself, +// Unmarshalers implement UnmarshalJSON([]byte("null")) as a no-op. +// See https://pkg.go.dev/encoding/json#Unmarshaler for more information. +var nullLiteral = []byte("null") diff --git a/src/internal/cm/stream.go b/src/internal/cm/stream.go new file mode 100644 index 000000000..80ef062e9 --- /dev/null +++ b/src/internal/cm/stream.go @@ -0,0 +1,15 @@ +package cm + +// Stream represents the Component Model [stream] type. +// A stream is a special case of stream. In non-error cases, +// a stream delivers exactly one value before being automatically closed. +// +// [stream]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/Explainer.md#asynchronous-value-types +type Stream[T any] struct { + _ HostLayout + stream[T] +} + +type stream[T any] uint32 + +// TODO: implement methods on type stream diff --git a/src/internal/cm/variant.go b/src/internal/cm/variant.go index 24703641d..d0def34bb 100644 --- a/src/internal/cm/variant.go +++ b/src/internal/cm/variant.go @@ -3,10 +3,9 @@ package cm import "unsafe" // Discriminant is the set of types that can represent the tag or discriminator of a variant. -// Use bool for 2-case variant types, result, or option types, uint8 where there are 256 or -// fewer cases, uint16 for up to 65,536 cases, or uint32 for anything greater. +// Use uint8 where there are 256 or fewer cases, uint16 for up to 65,536 cases, or uint32 for anything greater. type Discriminant interface { - bool | uint8 | uint16 | uint32 + uint8 | uint16 | uint32 } // Variant represents a loosely-typed Component Model variant.