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// Copyright 2021 The Tint 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.
// Package parser provides a basic parser for the Tint builtin definition
// language
package parser
import (
"fmt"
"dawn.googlesource.com/dawn/tools/src/cmd/builtin-gen/ast"
"dawn.googlesource.com/dawn/tools/src/cmd/builtin-gen/lexer"
"dawn.googlesource.com/dawn/tools/src/cmd/builtin-gen/tok"
)
// Parse produces a list of tokens for the given source code
func Parse(source, filepath string) (*ast.AST, error) {
runes := []rune(source)
tokens, err := lexer.Lex(runes, filepath)
if err != nil {
return nil, err
}
p := parser{tokens: tokens}
return p.parse()
}
type parser struct {
tokens []tok.Token
err error
}
func (p *parser) parse() (*ast.AST, error) {
out := ast.AST{}
var decorations ast.Decorations
for p.err == nil {
t := p.peek(0)
if t == nil {
break
}
switch t.Kind {
case tok.Ldeco:
decorations = append(decorations, p.decorations()...)
case tok.Enum:
if len(decorations) > 0 {
p.err = fmt.Errorf("%v unexpected decoration", decorations[0].Source)
}
out.Enums = append(out.Enums, p.enumDecl())
case tok.Match:
if len(decorations) > 0 {
p.err = fmt.Errorf("%v unexpected decoration", decorations[0].Source)
}
out.Matchers = append(out.Matchers, p.matcherDecl())
case tok.Type:
out.Types = append(out.Types, p.typeDecl(decorations))
decorations = nil
case tok.Function:
out.Functions = append(out.Functions, p.functionDecl(decorations))
decorations = nil
default:
p.err = fmt.Errorf("%v unexpected token '%v'", t.Source, t.Kind)
}
if p.err != nil {
return nil, p.err
}
}
return &out, nil
}
func (p *parser) enumDecl() ast.EnumDecl {
p.expect(tok.Enum, "enum declaration")
name := p.expect(tok.Identifier, "enum name")
e := ast.EnumDecl{Source: name.Source, Name: string(name.Runes)}
p.expect(tok.Lbrace, "enum declaration")
for p.err == nil && p.match(tok.Rbrace) == nil {
e.Entries = append(e.Entries, p.enumEntry())
}
return e
}
func (p *parser) enumEntry() ast.EnumEntry {
decos := p.decorations()
name := p.expect(tok.Identifier, "enum entry")
return ast.EnumEntry{Source: name.Source, Decorations: decos, Name: string(name.Runes)}
}
func (p *parser) matcherDecl() ast.MatcherDecl {
p.expect(tok.Match, "matcher declaration")
name := p.expect(tok.Identifier, "matcher name")
m := ast.MatcherDecl{Source: name.Source, Name: string(name.Runes)}
p.expect(tok.Colon, "matcher declaration")
for p.err == nil {
m.Options = append(m.Options, p.templatedName())
if p.match(tok.Or) == nil {
break
}
}
return m
}
func (p *parser) typeDecl(decos ast.Decorations) ast.TypeDecl {
p.expect(tok.Type, "type declaration")
name := p.expect(tok.Identifier, "type name")
m := ast.TypeDecl{
Source: name.Source,
Decorations: decos,
Name: string(name.Runes),
}
if p.peekIs(0, tok.Lt) {
m.TemplateParams = p.templateParams()
}
return m
}
func (p *parser) decorations() ast.Decorations {
if p.match(tok.Ldeco) == nil {
return nil
}
out := ast.Decorations{}
for p.err == nil {
name := p.expect(tok.Identifier, "decoration name")
values := []string{}
if p.match(tok.Lparen) != nil {
for p.err == nil {
values = append(values, p.string())
if p.match(tok.Comma) == nil {
break
}
}
p.expect(tok.Rparen, "decoration values")
}
out = append(out, ast.Decoration{
Source: name.Source,
Name: string(name.Runes),
Values: values,
})
if !p.peekIs(0, tok.Comma) {
break
}
}
p.expect(tok.Rdeco, "decoration list")
return out
}
func (p *parser) functionDecl(decos ast.Decorations) ast.FunctionDecl {
p.expect(tok.Function, "function declaration")
name := p.expect(tok.Identifier, "function name")
f := ast.FunctionDecl{
Source: name.Source,
Decorations: decos,
Name: string(name.Runes),
}
if p.peekIs(0, tok.Lt) {
f.TemplateParams = p.templateParams()
}
f.Parameters = p.parameters()
if p.match(tok.Arrow) != nil {
ret := p.templatedName()
f.ReturnType = &ret
}
return f
}
func (p *parser) parameters() ast.Parameters {
l := ast.Parameters{}
p.expect(tok.Lparen, "function parameter list")
if p.match(tok.Rparen) == nil {
for p.err == nil {
l = append(l, p.parameter())
if p.match(tok.Comma) == nil {
break
}
}
p.expect(tok.Rparen, "function parameter list")
}
return l
}
func (p *parser) parameter() ast.Parameter {
if p.peekIs(1, tok.Colon) {
// name type
name := p.expect(tok.Identifier, "parameter name")
p.expect(tok.Colon, "parameter type")
return ast.Parameter{
Source: name.Source,
Name: string(name.Runes),
Type: p.templatedName(),
}
}
// type
ty := p.templatedName()
return ast.Parameter{
Source: ty.Source,
Type: ty,
}
}
func (p *parser) string() string {
s := p.expect(tok.String, "string")
return string(s.Runes)
}
func (p *parser) templatedName() ast.TemplatedName {
name := p.expect(tok.Identifier, "type name")
m := ast.TemplatedName{Source: name.Source, Name: string(name.Runes)}
if p.match(tok.Lt) != nil {
for p.err == nil {
m.TemplateArgs = append(m.TemplateArgs, p.templatedName())
if p.match(tok.Comma) == nil {
break
}
}
p.expect(tok.Gt, "template argument type list")
}
return m
}
func (p *parser) templateParams() ast.TemplateParams {
t := ast.TemplateParams{}
p.expect(tok.Lt, "template parameter list")
for p.err == nil && p.peekIs(0, tok.Identifier) {
t = append(t, p.templateParam())
}
p.expect(tok.Gt, "template parameter list")
return t
}
func (p *parser) templateParam() ast.TemplateParam {
name := p.match(tok.Identifier)
t := ast.TemplateParam{
Source: name.Source,
Name: string(name.Runes),
}
if p.match(tok.Colon) != nil {
t.Type = p.templatedName()
}
p.match(tok.Comma)
return t
}
func (p *parser) expect(kind tok.Kind, use string) tok.Token {
if p.err != nil {
return tok.Invalid
}
t := p.match(kind)
if t == nil {
if len(p.tokens) > 0 {
p.err = fmt.Errorf("%v expected '%v' for %v, got '%v'",
p.tokens[0].Source, kind, use, p.tokens[0].Kind)
} else {
p.err = fmt.Errorf("expected '%v' for %v, but reached end of file", kind, use)
}
return tok.Invalid
}
return *t
}
func (p *parser) ident(use string) string {
return string(p.expect(tok.Identifier, use).Runes)
}
// TODO(bclayton): Currently unused, but will be needed for integer bounds
// func (p *parser) integer(use string) int {
// t := p.expect(tok.Integer, use)
// if t.Kind != tok.Integer {
// return 0
// }
// i, err := strconv.Atoi(string(t.Runes))
// if err != nil {
// p.err = err
// return 0
// }
// return i
// }
func (p *parser) match(kind tok.Kind) *tok.Token {
if p.err != nil || len(p.tokens) == 0 {
return nil
}
t := p.tokens[0]
if t.Kind != kind {
return nil
}
p.tokens = p.tokens[1:]
return &t
}
func (p *parser) peekIs(i int, kind tok.Kind) bool {
t := p.peek(i)
if t == nil {
return false
}
return t.Kind == kind
}
func (p *parser) peek(i int) *tok.Token {
if len(p.tokens) <= i {
return nil
}
return &p.tokens[i]
}