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hugo/tpl/templates/templates.go

105 lines
2.8 KiB
Go

// Copyright 2018 The Hugo Authors. All rights reserved.
//
// 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 templates provides template functions for working with templates.
package templates
import (
"context"
"fmt"
"strconv"
"sync/atomic"
"github.com/gohugoio/hugo/common/hashing"
"github.com/gohugoio/hugo/deps"
"github.com/gohugoio/hugo/tpl"
"github.com/mitchellh/mapstructure"
)
// New returns a new instance of the templates-namespaced template functions.
func New(deps *deps.Deps) *Namespace {
ns := &Namespace{
deps: deps,
}
return ns
}
// Namespace provides template functions for the "templates" namespace.
type Namespace struct {
deps *deps.Deps
}
// Exists returns whether the template with the given name exists.
// Note that this is the Unix-styled relative path including filename suffix,
// e.g. partials/header.html
func (ns *Namespace) Exists(name string) bool {
return ns.deps.Tmpl().HasTemplate(name)
}
// Defer defers the execution of a template block.
func (ns *Namespace) Defer(args ...any) (bool, error) {
// Prevent defer from being used in content adapters,
// that just doesn't work.
ns.deps.Site.CheckReady()
if len(args) != 0 {
return false, fmt.Errorf("Defer does not take any arguments")
}
return true, nil
}
var defferedIDCounter atomic.Uint64
type DeferOpts struct {
// Optional cache key. If set, the deferred block will be executed
// once per unique key.
Key string
// Optional data context to use when executing the deferred block.
Data any
}
// DoDefer defers the execution of a template block.
// For internal use only.
func (ns *Namespace) DoDefer(ctx context.Context, id string, optsv any) string {
var opts DeferOpts
if optsv != nil {
if err := mapstructure.WeakDecode(optsv, &opts); err != nil {
panic(err)
}
}
templateName := id
var key string
if opts.Key != "" {
key = hashing.MD5FromStringHexEncoded(opts.Key)
} else {
key = strconv.FormatUint(defferedIDCounter.Add(1), 10)
}
id = fmt.Sprintf("%s_%s%s", id, key, tpl.HugoDeferredTemplateSuffix)
_, _ = ns.deps.BuildState.DeferredExecutions.Executions.GetOrCreate(id,
func() (*tpl.DeferredExecution, error) {
return &tpl.DeferredExecution{
TemplateName: templateName,
Ctx: ctx,
Data: opts.Data,
Executed: false,
}, nil
})
return id
}