ref: d6ed17c60fd13c933347110c720afa09e04df1c8
dir: /tpl/internal/templatefuncsRegistry.go/
// Copyright 2017-present The Hugo Authors. All rights reserved.
//
// Portions Copyright The Go 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 internal
import (
"bytes"
"encoding/json"
"fmt"
"go/doc"
"go/parser"
"go/token"
"io/ioutil"
"log"
"os"
"path/filepath"
"reflect"
"runtime"
"strings"
"sync"
"github.com/gohugoio/hugo/deps"
)
// TemplateFuncsNamespaceRegistry describes a registry of functions that provide
// namespaces.
var TemplateFuncsNamespaceRegistry []func(d *deps.Deps) *TemplateFuncsNamespace
// AddTemplateFuncsNamespace adds a given function to a registry.
func AddTemplateFuncsNamespace(ns func(d *deps.Deps) *TemplateFuncsNamespace) {
TemplateFuncsNamespaceRegistry = append(TemplateFuncsNamespaceRegistry, ns)
}
// TemplateFuncsNamespace represents a template function namespace.
type TemplateFuncsNamespace struct {
// The namespace name, "strings", "lang", etc.
Name string
// This is the method receiver.
Context func(v ...interface{}) interface{}
// Additional info, aliases and examples, per method name.
MethodMappings map[string]TemplateFuncMethodMapping
}
// TemplateFuncsNamespaces is a slice of TemplateFuncsNamespace.
type TemplateFuncsNamespaces []*TemplateFuncsNamespace
// AddMethodMapping adds a method to a template function namespace.
func (t *TemplateFuncsNamespace) AddMethodMapping(m interface{}, aliases []string, examples [][2]string) {
if t.MethodMappings == nil {
t.MethodMappings = make(map[string]TemplateFuncMethodMapping)
}
name := methodToName(m)
// sanity check
for _, e := range examples {
if e[0] == "" {
panic(t.Name + ": Empty example for " + name)
}
}
for _, a := range aliases {
if a == "" {
panic(t.Name + ": Empty alias for " + name)
}
}
t.MethodMappings[name] = TemplateFuncMethodMapping{
Method: m,
Aliases: aliases,
Examples: examples,
}
}
// TemplateFuncMethodMapping represents a mapping of functions to methods for a
// given namespace.
type TemplateFuncMethodMapping struct {
Method interface{}
// Any template funcs aliases. This is mainly motivated by keeping
// backwards compatibility, but some new template funcs may also make
// sense to give short and snappy aliases.
// Note that these aliases are global and will be merged, so the last
// key will win.
Aliases []string
// A slice of input/expected examples.
// We keep it a the namespace level for now, but may find a way to keep track
// of the single template func, for documentation purposes.
// Some of these, hopefully just a few, may depend on some test data to run.
Examples [][2]string
}
func methodToName(m interface{}) string {
name := runtime.FuncForPC(reflect.ValueOf(m).Pointer()).Name()
name = filepath.Ext(name)
name = strings.TrimPrefix(name, ".")
name = strings.TrimSuffix(name, "-fm")
return name
}
type goDocFunc struct {
Name string
Description string
Args []string
Aliases []string
Examples [][2]string
}
func (t goDocFunc) toJSON() ([]byte, error) {
args, err := json.Marshal(t.Args)
if err != nil {
return nil, err
}
aliases, err := json.Marshal(t.Aliases)
if err != nil {
return nil, err
}
examples, err := json.Marshal(t.Examples)
if err != nil {
return nil, err
}
var buf bytes.Buffer
buf.WriteString(fmt.Sprintf(`%q:
{ "Description": %q, "Args": %s, "Aliases": %s, "Examples": %s }
`, t.Name, t.Description, args, aliases, examples))
return buf.Bytes(), nil
}
// MarshalJSON returns the JSON encoding of namespaces.
func (namespaces TemplateFuncsNamespaces) MarshalJSON() ([]byte, error) {
var buf bytes.Buffer
buf.WriteString("{")
for i, ns := range namespaces {
if i != 0 {
buf.WriteString(",")
}
b, err := ns.toJSON()
if err != nil {
return nil, err
}
buf.Write(b)
}
buf.WriteString("}")
return buf.Bytes(), nil
}
func (t *TemplateFuncsNamespace) toJSON() ([]byte, error) {
var buf bytes.Buffer
godoc := getGetTplPackagesGoDoc()[t.Name]
var funcs []goDocFunc
buf.WriteString(fmt.Sprintf(`%q: {`, t.Name))
ctx := t.Context()
ctxType := reflect.TypeOf(ctx)
for i := 0; i < ctxType.NumMethod(); i++ {
method := ctxType.Method(i)
f := goDocFunc{
Name: method.Name,
}
methodGoDoc := godoc[method.Name]
if mapping, ok := t.MethodMappings[method.Name]; ok {
f.Aliases = mapping.Aliases
f.Examples = mapping.Examples
f.Description = methodGoDoc.Description
f.Args = methodGoDoc.Args
}
funcs = append(funcs, f)
}
for i, f := range funcs {
if i != 0 {
buf.WriteString(",")
}
funcStr, err := f.toJSON()
if err != nil {
return nil, err
}
buf.Write(funcStr)
}
buf.WriteString("}")
return buf.Bytes(), nil
}
type methodGoDocInfo struct {
Description string
Args []string
}
var (
tplPackagesGoDoc map[string]map[string]methodGoDocInfo
tplPackagesGoDocInit sync.Once
)
func getGetTplPackagesGoDoc() map[string]map[string]methodGoDocInfo {
tplPackagesGoDocInit.Do(func() {
tplPackagesGoDoc = make(map[string]map[string]methodGoDocInfo)
pwd, err := os.Getwd()
if err != nil {
log.Fatal(err)
}
fset := token.NewFileSet()
// pwd will be inside one of the namespace packages during tests
var basePath string
if strings.Contains(pwd, "tpl") {
basePath = filepath.Join(pwd, "..")
} else {
basePath = filepath.Join(pwd, "tpl")
}
files, err := ioutil.ReadDir(basePath)
if err != nil {
log.Fatal(err)
}
for _, fi := range files {
if !fi.IsDir() {
continue
}
namespaceDoc := make(map[string]methodGoDocInfo)
packagePath := filepath.Join(basePath, fi.Name())
d, err := parser.ParseDir(fset, packagePath, nil, parser.ParseComments)
if err != nil {
log.Fatal(err)
}
for _, f := range d {
p := doc.New(f, "./", 0)
for _, t := range p.Types {
if t.Name == "Namespace" {
for _, tt := range t.Methods {
var args []string
for _, p := range tt.Decl.Type.Params.List {
for _, pp := range p.Names {
args = append(args, pp.Name)
}
}
description := strings.TrimSpace(tt.Doc)
di := methodGoDocInfo{Description: description, Args: args}
namespaceDoc[tt.Name] = di
}
}
}
}
tplPackagesGoDoc[fi.Name()] = namespaceDoc
}
})
return tplPackagesGoDoc
}