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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 gen
import (
"fmt"
"io"
"reflect"
"strings"
"text/template"
"unicode"
"dawn.googlesource.com/dawn/tools/src/cmd/builtin-gen/sem"
)
type generator struct {
s *sem.Sem
t *template.Template
cached struct {
builtinTable *BuiltinTable // lazily built by builtinTable()
permuter *Permuter // lazily built by permute()
}
}
// WriteFile is a function that Generate() may call to emit a new file from a
// template.
// relpath is the relative path from the currently executing template.
// content is the file content to write.
type WriteFile func(relpath, content string) error
// Generate executes the template tmpl using the provided semantic
// information, writing the output to w.
// See https://golang.org/pkg/text/template/ for documentation on the template
// syntax.
func Generate(s *sem.Sem, tmpl string, w io.Writer, writeFile WriteFile) error {
g := generator{s: s}
return g.generate(tmpl, w, writeFile)
}
func (g *generator) generate(tmpl string, w io.Writer, writeFile WriteFile) error {
t, err := template.New("<template>").Funcs(map[string]interface{}{
"Map": newMap,
"Iterate": iterate,
"Title": strings.Title,
"PascalCase": pascalCase,
"SplitDisplayName": splitDisplayName,
"HasPrefix": strings.HasPrefix,
"HasSuffix": strings.HasSuffix,
"TrimPrefix": strings.TrimPrefix,
"TrimSuffix": strings.TrimSuffix,
"TrimLeft": strings.TrimLeft,
"TrimRight": strings.TrimRight,
"IsEnumEntry": is(sem.EnumEntry{}),
"IsEnumMatcher": is(sem.EnumMatcher{}),
"IsFQN": is(sem.FullyQualifiedName{}),
"IsInt": is(1),
"IsTemplateEnumParam": is(sem.TemplateEnumParam{}),
"IsTemplateNumberParam": is(sem.TemplateNumberParam{}),
"IsTemplateTypeParam": is(sem.TemplateTypeParam{}),
"IsType": is(sem.Type{}),
"IsDeclarable": isDeclarable,
"IsFirstIn": isFirstIn,
"IsLastIn": isLastIn,
"BuiltinTable": g.builtinTable,
"Permute": g.permute,
"Eval": g.eval,
"WriteFile": func(relpath, content string) (string, error) { return "", writeFile(relpath, content) },
}).Option("missingkey=error").
Parse(tmpl)
if err != nil {
return err
}
g.t = t
return t.Execute(w, map[string]interface{}{
"Sem": g.s,
})
}
// eval executes the sub-template with the given name and argument, returning
// the generated output
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
}
// builtinTable lazily calls and returns the result of buildBuiltinTable(),
// caching the result for repeated calls.
func (g *generator) builtinTable() (*BuiltinTable, error) {
if g.cached.builtinTable == nil {
var err error
g.cached.builtinTable, err = buildBuiltinTable(g.s)
if err != nil {
return nil, err
}
}
return g.cached.builtinTable, nil
}
// permute lazily calls buildPermuter(), caching the result for repeated
// calls, then passes the argument to Permutator.Permute()
func (g *generator) permute(overload *sem.Overload) ([]Permutation, error) {
if g.cached.permuter == nil {
var err error
g.cached.permuter, err = buildPermuter(g.s)
if err != nil {
return nil, err
}
}
return g.cached.permuter.Permute(overload)
}
// 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 the type of 'ty'.
func is(ty interface{}) func(interface{}) bool {
rty := reflect.TypeOf(ty)
return func(v interface{}) bool {
ty := reflect.TypeOf(v)
return ty == rty || ty == reflect.PtrTo(rty)
}
}
// isFirstIn returns true if v is the first element of the given slice.
func isFirstIn(v, slice interface{}) bool {
s := reflect.ValueOf(slice)
count := s.Len()
if count == 0 {
return false
}
return s.Index(0).Interface() == v
}
// isFirstIn returns true if v is the last element of the given slice.
func isLastIn(v, slice interface{}) bool {
s := reflect.ValueOf(slice)
count := s.Len()
if count == 0 {
return false
}
return s.Index(count-1).Interface() == v
}
// iterate returns a slice of length 'n', with each element equal to its index.
// Useful for: {{- range Iterate $n -}}<this will be looped $n times>{{end}}
func iterate(n int) []int {
out := make([]int, n)
for i := range out {
out[i] = i
}
return out
}
// isDeclarable returns false if the FullyQualifiedName starts with a
// leading underscore. These are undeclarable as WGSL does not allow identifers
// to have a leading underscore.
func isDeclarable(fqn sem.FullyQualifiedName) bool {
return !strings.HasPrefix(fqn.Target.GetName(), "_")
}
// pascalCase returns the snake-case string s transformed into 'PascalCase',
// Rules:
// * The first letter of the string is capitalized
// * Characters following an underscore 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 == '_' {
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()
}
// splitDisplayName splits displayName into parts, where text wrapped in {}
// braces are not quoted and the rest is quoted. This is used to help process
// the string value of the [[display()]] decoration. For example:
// splitDisplayName("vec{N}<{T}>")
// would return the strings:
// [`"vec"`, `N`, `"<"`, `T`, `">"`]
func splitDisplayName(displayName string) []string {
parts := []string{}
pending := strings.Builder{}
for _, r := range displayName {
switch r {
case '{':
if pending.Len() > 0 {
parts = append(parts, fmt.Sprintf(`"%v"`, pending.String()))
pending.Reset()
}
case '}':
if pending.Len() > 0 {
parts = append(parts, pending.String())
pending.Reset()
}
default:
pending.WriteRune(r)
}
}
if pending.Len() > 0 {
parts = append(parts, fmt.Sprintf(`"%v"`, pending.String()))
}
return parts
}