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// Copyright 2021 The Dawn Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// idlgen is a tool used to generate code from WebIDL files and a golang
// template file
package main
import (
"flag"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"reflect"
"strings"
"text/template"
"unicode"
"github.com/ben-clayton/webidlparser/ast"
"github.com/ben-clayton/webidlparser/parser"
)
func main() {
if err := run(); err != nil {
fmt.Println(err)
os.Exit(1)
}
}
func showUsage() {
fmt.Println(`
idlgen is a tool used to generate code from WebIDL files and a golang
template file
Usage:
idlgen --template=<template-path> --output=<output-path> <idl-file> [<idl-file>...]`)
os.Exit(1)
}
func run() error {
var templatePath string
var outputPath string
flag.StringVar(&templatePath, "template", "", "the template file run with the parsed WebIDL files")
flag.StringVar(&outputPath, "output", "", "the output file")
flag.Parse()
idlFiles := flag.Args()
// Check all required arguments are provided
if templatePath == "" || outputPath == "" || len(idlFiles) == 0 {
showUsage()
}
// Open up the output file
out := os.Stdout
if outputPath != "" {
dir := filepath.Dir(outputPath)
if err := os.MkdirAll(dir, 0777); err != nil {
return fmt.Errorf("failed to create output directory '%v'", dir)
}
file, err := os.Create(outputPath)
if err != nil {
return fmt.Errorf("failed to open output file '%v'", outputPath)
}
out = file
defer file.Close()
}
// Read the template file
tmpl, err := ioutil.ReadFile(templatePath)
if err != nil {
return fmt.Errorf("failed to open template file '%v'", templatePath)
}
// idl is the combination of the parsed idlFiles
idl := &ast.File{}
// Parse each of the WebIDL files and add the declarations to idl
for _, path := range idlFiles {
content, err := ioutil.ReadFile(path)
if err != nil {
return fmt.Errorf("failed to open file '%v'", path)
}
fileIDL := parser.Parse(string(content))
if numErrs := len(fileIDL.Errors); numErrs != 0 {
errs := make([]string, numErrs)
for i, e := range fileIDL.Errors {
errs[i] = e.Message
}
return fmt.Errorf("errors found while parsing %v:\n%v", path, strings.Join(errs, "\n"))
}
idl.Declarations = append(idl.Declarations, fileIDL.Declarations...)
}
// Initialize the generator
g := generator{t: template.New(templatePath)}
g.workingDir = filepath.Dir(templatePath)
g.funcs = map[string]interface{}{
// Functions exposed to the template
"AttributesOf": attributesOf,
"ConstantsOf": constantsOf,
"EnumEntryName": enumEntryName,
"Eval": g.eval,
"HasAnnotation": hasAnnotation,
"FlattenedAttributesOf": g.flattenedAttributesOf,
"FlattenedConstantsOf": g.flattenedConstantsOf,
"FlattenedMethodsOf": g.flattenedMethodsOf,
"Include": g.include,
"IsBasicLiteral": is(ast.BasicLiteral{}),
"IsInitializer": isInitializer,
"IsDefaultDictionaryLiteral": is(ast.DefaultDictionaryLiteral{}),
"IsDictionary": is(ast.Dictionary{}),
"IsEnum": is(ast.Enum{}),
"IsInterface": is(ast.Interface{}),
"IsInterfaceOrNamespace": is(ast.Interface{}, ast.Namespace{}),
"IsMember": is(ast.Member{}),
"IsNamespace": is(ast.Namespace{}),
"IsNullableType": is(ast.NullableType{}),
"IsParametrizedType": is(ast.ParametrizedType{}),
"IsRecordType": is(ast.RecordType{}),
"IsSequenceType": is(ast.SequenceType{}),
"IsTypedef": is(ast.Typedef{}),
"IsTypeName": is(ast.TypeName{}),
"IsUndefinedType": isUndefinedType,
"IsUnionType": is(ast.UnionType{}),
"Lookup": g.lookup,
"MethodsOf": methodsOf,
"SetlikeOf": setlikeOf,
"Title": strings.Title,
}
t, err := g.t.
Option("missingkey=invalid").
Funcs(g.funcs).
Parse(string(tmpl))
if err != nil {
return fmt.Errorf("failed to parse template file '%v': %w", templatePath, err)
}
// simplify the definitions in the WebIDL before passing this to the template
idl, declarations := simplify(idl)
// Patch the IDL for the differences we need compared to the upstream IDL.
patch(idl, declarations)
g.declarations = declarations
// Write the file header
fmt.Fprintf(out, header, strings.Join(os.Args[1:], "\n// "))
// Execute the template
return t.Execute(out, idl)
}
// declarations is a map of WebIDL declaration name to its AST node.
type declarations map[string]ast.Decl
// nameOf returns the name of the AST node n.
// Returns an empty string if the node is not named.
func nameOf(n ast.Node) string {
switch n := n.(type) {
case *ast.Namespace:
return n.Name
case *ast.Interface:
return n.Name
case *ast.Dictionary:
return n.Name
case *ast.Enum:
return n.Name
case *ast.Typedef:
return n.Name
case *ast.Mixin:
return n.Name
case *ast.Includes:
return ""
default:
panic(fmt.Errorf("unhandled AST declaration %T", n))
}
}
// simplify processes the AST 'in', returning a new AST that:
// * Has all partial interfaces merged into a single interface.
// * Has all mixins flattened into their place of use.
// * Has all the declarations ordered in dependency order (leaf first)
// simplify also returns the map of declarations in the AST.
func simplify(in *ast.File) (*ast.File, declarations) {
s := simplifier{
declarations: declarations{},
registered: map[string]bool{},
out: &ast.File{},
}
// Walk the IDL declarations to merge together partial interfaces and embed
// mixins into their uses.
{
interfaces := map[string]*ast.Interface{}
mixins := map[string]*ast.Mixin{}
includes := []*ast.Includes{}
for _, d := range in.Declarations {
switch d := d.(type) {
case *ast.Interface:
if i, ok := interfaces[d.Name]; ok {
// Merge partial body into one interface
i.Members = append(i.Members, d.Members...)
} else {
clone := *d
d := &clone
interfaces[d.Name] = d
s.declarations[d.Name] = d
}
case *ast.Mixin:
mixins[d.Name] = d
s.declarations[d.Name] = d
case *ast.Includes:
includes = append(includes, d)
default:
if name := nameOf(d); name != "" {
s.declarations[nameOf(d)] = d
}
}
}
// Merge mixin into interface
for _, include := range includes {
i, ok := interfaces[include.Name]
if !ok {
panic(fmt.Errorf("%v includes %v, but %v is not an interface", include.Name, include.Source, include.Name))
}
m, ok := mixins[include.Source]
if !ok {
panic(fmt.Errorf("%v includes %v, but %v is not an mixin", include.Name, include.Source, include.Source))
}
// Merge mixin into the interface
for _, member := range m.Members {
if member, ok := member.(*ast.Member); ok {
i.Members = append(i.Members, member)
}
}
}
}
// Now traverse the declarations in to produce the dependency-ordered
// output `s.out`.
for _, d := range in.Declarations {
if name := nameOf(d); name != "" {
s.visit(s.declarations[nameOf(d)])
}
}
return s.out, s.declarations
}
// simplifier holds internal state for simplify()
type simplifier struct {
// all AST declarations
declarations declarations
// set of visited declarations
registered map[string]bool
// the dependency-ordered output
out *ast.File
}
// visit traverses the AST declaration 'd' adding all dependent declarations to
// s.out.
func (s *simplifier) visit(d ast.Decl) {
register := func(name string) bool {
if s.registered[name] {
return true
}
s.registered[name] = true
return false
}
switch d := d.(type) {
case *ast.Namespace:
if register(d.Name) {
return
}
for _, m := range d.Members {
if m, ok := m.(*ast.Member); ok {
s.visitType(m.Type)
for _, p := range m.Parameters {
s.visitType(p.Type)
}
}
}
case *ast.Interface:
if register(d.Name) {
return
}
if d, ok := s.declarations[d.Inherits]; ok {
s.visit(d)
}
for _, m := range d.Members {
if m, ok := m.(*ast.Member); ok {
s.visitType(m.Type)
for _, p := range m.Parameters {
s.visitType(p.Type)
}
}
}
case *ast.Dictionary:
if register(d.Name) {
return
}
if d, ok := s.declarations[d.Inherits]; ok {
s.visit(d)
}
for _, m := range d.Members {
s.visitType(m.Type)
for _, p := range m.Parameters {
s.visitType(p.Type)
}
}
case *ast.Typedef:
if register(d.Name) {
return
}
s.visitType(d.Type)
case *ast.Mixin:
if register(d.Name) {
return
}
for _, m := range d.Members {
if m, ok := m.(*ast.Member); ok {
s.visitType(m.Type)
for _, p := range m.Parameters {
s.visitType(p.Type)
}
}
}
case *ast.Enum:
if register(d.Name) {
return
}
case *ast.Includes:
if register(d.Name) {
return
}
default:
panic(fmt.Errorf("unhandled AST declaration %T", d))
}
s.out.Declarations = append(s.out.Declarations, d)
}
// visitType traverses the AST type 't' adding all dependent declarations to
// s.out.
func (s *simplifier) visitType(t ast.Type) {
switch t := t.(type) {
case *ast.TypeName:
if d, ok := s.declarations[t.Name]; ok {
s.visit(d)
}
case *ast.UnionType:
for _, t := range t.Types {
s.visitType(t)
}
case *ast.ParametrizedType:
for _, t := range t.Elems {
s.visitType(t)
}
case *ast.NullableType:
s.visitType(t.Type)
case *ast.SequenceType:
s.visitType(t.Elem)
case *ast.RecordType:
s.visitType(t.Elem)
default:
panic(fmt.Errorf("unhandled AST type %T", t))
}
}
func patch(idl *ast.File, decl declarations) {
// Add [SameObject] to GPUDevice.lost
for _, member := range decl["GPUDevice"].(*ast.Interface).Members {
if m := member.(*ast.Member); m != nil && m.Name == "lost" {
annotation := &ast.Annotation{}
annotation.Name = "SameObject"
m.Annotations = append(m.Annotations, annotation)
}
}
}
// generator holds the template generator state
type generator struct {
// the root template
t *template.Template
// the working directory
workingDir string
// map of function name to function exposed to the template executor
funcs map[string]interface{}
// dependency-sorted declarations
declarations declarations
}
// eval executes the sub-template with the given name and arguments, returning
// the generated output
// args can be a single argument:
//
// arg[0]
//
// or a list of name-value pairs:
//
// (args[0]: name, args[1]: value), (args[2]: name, args[3]: value)...
func (g *generator) eval(template string, args ...interface{}) (string, error) {
target := g.t.Lookup(template)
if target == nil {
return "", fmt.Errorf("template '%v' not found", template)
}
sb := strings.Builder{}
var err error
if len(args) == 1 {
err = target.Execute(&sb, args[0])
} else {
m := newMap()
if len(args)%2 != 0 {
return "", fmt.Errorf("Eval expects a single argument or list name-value pairs")
}
for i := 0; i < len(args); i += 2 {
name, ok := args[i].(string)
if !ok {
return "", fmt.Errorf("Eval argument %v is not a string", i)
}
m.Put(name, args[i+1])
}
err = target.Execute(&sb, m)
}
if err != nil {
return "", fmt.Errorf("while evaluating '%v': %v", template, err)
}
return sb.String(), nil
}
// lookup returns the declaration with the given name, or nil if not found.
func (g *generator) lookup(name string) ast.Decl {
return g.declarations[name]
}
// include loads the template with the given path, importing the declarations
// into the scope of the current template.
func (g *generator) include(path string) (string, error) {
t, err := g.t.
Option("missingkey=invalid").
Funcs(g.funcs).
ParseFiles(filepath.Join(g.workingDir, path))
if err != nil {
return "", err
}
g.t.AddParseTree(path, t.Tree)
return "", nil
}
// Map is a simple generic key-value map, which can be used in the template
type Map map[interface{}]interface{}
func newMap() Map { return Map{} }
// Put adds the key-value pair into the map.
// Put always returns an empty string so nothing is printed in the template.
func (m Map) Put(key, value interface{}) string {
m[key] = value
return ""
}
// Get looks up and returns the value with the given key. If the map does not
// contain the given key, then nil is returned.
func (m Map) Get(key interface{}) interface{} {
return m[key]
}
// is returns a function that returns true if the value passed to the function
// matches any of the types of the objects in 'prototypes'.
func is(prototypes ...interface{}) func(interface{}) bool {
types := make([]reflect.Type, len(prototypes))
for i, p := range prototypes {
types[i] = reflect.TypeOf(p)
}
return func(v interface{}) bool {
ty := reflect.TypeOf(v)
for _, rty := range types {
if ty == rty || ty == reflect.PtrTo(rty) {
return true
}
}
return false
}
}
// isInitializer returns true if the object is a constructor ast.Member.
func isInitializer(v interface{}) bool {
if member, ok := v.(*ast.Member); ok {
if ty, ok := member.Type.(*ast.TypeName); ok {
return ty.Name == "constructor"
}
}
return false
}
// isUndefinedType returns true if the type is 'undefined'
func isUndefinedType(ty ast.Type) bool {
if ty, ok := ty.(*ast.TypeName); ok {
return ty.Name == "undefined"
}
return false
}
// enumEntryName formats the enum entry name 's' for use in a C++ enum.
func enumEntryName(s string) string {
return "k" + strings.ReplaceAll(pascalCase(strings.Trim(s, `"`)), "-", "")
}
func findAnnotation(list []*ast.Annotation, name string) *ast.Annotation {
for _, annotation := range list {
if annotation.Name == name {
return annotation
}
}
return nil
}
func hasAnnotation(obj interface{}, name string) bool {
switch obj := obj.(type) {
case *ast.Interface:
return findAnnotation(obj.Annotations, name) != nil
case *ast.Member:
return findAnnotation(obj.Annotations, name) != nil
case *ast.Namespace:
return findAnnotation(obj.Annotations, name) != nil
case *ast.Parameter:
return findAnnotation(obj.Annotations, name) != nil
case *ast.Typedef:
return findAnnotation(obj.Annotations, name) != nil || findAnnotation(obj.TypeAnnotations, name) != nil
}
panic("Unhandled AST node type in hasAnnotation")
}
// Method describes a WebIDL interface method
type Method struct {
// Name of the method
Name string
// The list of overloads of the method
Overloads []*ast.Member
}
// methodsOf returns all the methods of the given WebIDL interface.
func methodsOf(obj interface{}) []*Method {
iface, ok := obj.(*ast.Interface)
if !ok {
return nil
}
byName := map[string]*Method{}
out := []*Method{}
for _, member := range iface.Members {
member := member.(*ast.Member)
if !member.Const && !member.Attribute && !isInitializer(member) {
if method, ok := byName[member.Name]; ok {
method.Overloads = append(method.Overloads, member)
} else {
method = &Method{
Name: member.Name,
Overloads: []*ast.Member{member},
}
byName[member.Name] = method
out = append(out, method)
}
}
}
return out
}
// flattenedMethodsOf returns all the methods of the given WebIDL
// interface or namespace, as well as all the methods of the full inheritance
// chain
func (g *generator) flattenedMethodsOf(obj interface{}) []*Method {
switch obj := obj.(type) {
case *ast.Interface:
out := methodsOf(obj)
if base := g.lookup(obj.Inherits); base != nil {
out = append(out, g.flattenedMethodsOf(base)...)
}
return out
default:
return methodsOf(obj)
}
}
// attributesOf returns all the attributes of the given WebIDL interface or
// namespace.
func attributesOf(obj interface{}) []*ast.Member {
out := []*ast.Member{}
add := func(m interface{}) {
if m := m.(*ast.Member); m.Attribute {
out = append(out, m)
}
}
switch obj := obj.(type) {
case *ast.Interface:
for _, m := range obj.Members {
add(m)
}
case *ast.Namespace:
for _, m := range obj.Members {
add(m)
}
default:
return nil
}
return out
}
// flattenedAttributesOf returns all the attributes of the given WebIDL
// interface or namespace, as well as all the attributes of the full inheritance
// chain
func (g *generator) flattenedAttributesOf(obj interface{}) []*ast.Member {
switch obj := obj.(type) {
case *ast.Interface:
out := attributesOf(obj)
if base := g.lookup(obj.Inherits); base != nil {
out = append(out, g.flattenedAttributesOf(base)...)
}
return out
default:
return attributesOf(obj)
}
}
// constantsOf returns all the constant values of the given WebIDL interface or
// namespace.
func constantsOf(obj interface{}) []*ast.Member {
out := []*ast.Member{}
add := func(m interface{}) {
if m := m.(*ast.Member); m.Const {
out = append(out, m)
}
}
switch obj := obj.(type) {
case *ast.Interface:
for _, m := range obj.Members {
add(m)
}
case *ast.Namespace:
for _, m := range obj.Members {
add(m)
}
default:
return nil
}
return out
}
// flattenedConstantsOf returns all the constants of the given WebIDL
// interface or namespace, as well as all the constants of the full inheritance
// chain
func (g *generator) flattenedConstantsOf(obj interface{}) []*ast.Member {
switch obj := obj.(type) {
case *ast.Interface:
out := constantsOf(obj)
if base := g.lookup(obj.Inherits); base != nil {
out = append(out, g.flattenedConstantsOf(base)...)
}
return out
default:
return constantsOf(obj)
}
}
// setlikeOf returns the setlike ast.Pattern, if obj is a setlike interface.
func setlikeOf(obj interface{}) *ast.Pattern {
iface, ok := obj.(*ast.Interface)
if !ok {
return nil
}
for _, pattern := range iface.Patterns {
if pattern.Type == ast.Setlike {
return pattern
}
}
return nil
}
// pascalCase returns the snake-case string s transformed into 'PascalCase',
// Rules:
// * The first letter of the string is capitalized
// * Characters following an underscore, hyphen or number are capitalized
// * Underscores are removed from the returned string
// See: https://en.wikipedia.org/wiki/Camel_case
func pascalCase(s string) string {
b := strings.Builder{}
upper := true
for _, r := range s {
if r == '_' || r == '-' {
upper = true
continue
}
if upper {
b.WriteRune(unicode.ToUpper(r))
upper = false
} else {
b.WriteRune(r)
}
if unicode.IsNumber(r) {
upper = true
}
}
return b.String()
}
const header = `// Copyright 2021 The Dawn Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
////////////////////////////////////////////////////////////////////////////////
// File generated by tools/cmd/idlgen.go, with the arguments:
// %v
//
// Do not modify this file directly
////////////////////////////////////////////////////////////////////////////////
`