ref: bd98182dbde893a8a809661c70633741bbf63911
dir: /tpl/template.go/
// Copyright 2019 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 tpl
import (
"fmt"
"io"
"path/filepath"
"regexp"
"strings"
"time"
"github.com/gohugoio/hugo/output"
"github.com/gohugoio/hugo/common/herrors"
"github.com/gohugoio/hugo/hugofs"
"github.com/spf13/afero"
"html/template"
texttemplate "text/template"
"text/template/parse"
bp "github.com/gohugoio/hugo/bufferpool"
"github.com/gohugoio/hugo/metrics"
"github.com/pkg/errors"
)
var (
_ TemplateExecutor = (*TemplateAdapter)(nil)
_ TemplateInfoProvider = (*TemplateAdapter)(nil)
)
// TemplateHandler manages the collection of templates.
type TemplateHandler interface {
TemplateFinder
AddTemplate(name, tpl string) error
AddLateTemplate(name, tpl string) error
LoadTemplates(prefix string) error
NewTextTemplate() TemplateParseFinder
MarkReady() error
RebuildClone()
}
// TemplateVariants describes the possible variants of a template.
// All of these may be empty.
type TemplateVariants struct {
Language string
OutputFormat output.Format
}
// TemplateFinder finds templates.
type TemplateFinder interface {
TemplateLookup
TemplateLookupVariant
}
type TemplateLookup interface {
Lookup(name string) (Template, bool)
}
type TemplateLookupVariant interface {
// TODO(bep) this currently only works for shortcodes.
// We may unify and expand this variant pattern to the
// other templates, but we need this now for the shortcodes to
// quickly determine if a shortcode has a template for a given
// output format.
// It returns the template, if it was found or not and if there are
// alternative representations (output format, language).
// We are currently only interested in output formats, so we should improve
// this for speed.
LookupVariant(name string, variants TemplateVariants) (Template, bool, bool)
}
// Template is the common interface between text/template and html/template.
type Template interface {
Execute(wr io.Writer, data interface{}) error
Name() string
}
// TemplateInfoProvider provides some contextual information about a template.
type TemplateInfoProvider interface {
TemplateInfo() Info
}
// TemplateParser is used to parse ad-hoc templates, e.g. in the Resource chain.
type TemplateParser interface {
Parse(name, tpl string) (Template, error)
}
// TemplateParseFinder provides both parsing and finding.
type TemplateParseFinder interface {
TemplateParser
TemplateFinder
}
// TemplateExecutor adds some extras to Template.
type TemplateExecutor interface {
Template
ExecuteToString(data interface{}) (string, error)
Tree() string
}
// TemplateDebugger prints some debug info to stdoud.
type TemplateDebugger interface {
Debug()
}
// TemplateAdapter implements the TemplateExecutor interface.
type TemplateAdapter struct {
Template
Metrics metrics.Provider
Info Info
// The filesystem where the templates are stored.
Fs afero.Fs
// Maps to base template if relevant.
NameBaseTemplateName map[string]string
}
var baseOfRe = regexp.MustCompile("template: (.*?):")
func extractBaseOf(err string) string {
m := baseOfRe.FindStringSubmatch(err)
if len(m) == 2 {
return m[1]
}
return ""
}
// Execute executes the current template. The actual execution is performed
// by the embedded text or html template, but we add an implementation here so
// we can add a timer for some metrics.
func (t *TemplateAdapter) Execute(w io.Writer, data interface{}) (execErr error) {
defer func() {
// Panics in templates are a little bit too common (nil pointers etc.)
// See https://github.com/gohugoio/hugo/issues/5327
if r := recover(); r != nil {
execErr = t.addFileContext(t.Name(), fmt.Errorf(`panic in Execute: %s. See "https://github.com/gohugoio/hugo/issues/5327" for the reason why we cannot provide a better error message for this`, r))
}
}()
if t.Metrics != nil {
defer t.Metrics.MeasureSince(t.Name(), time.Now())
}
execErr = t.Template.Execute(w, data)
if execErr != nil {
execErr = t.addFileContext(t.Name(), execErr)
}
return
}
func (t *TemplateAdapter) TemplateInfo() Info {
return t.Info
}
// The identifiers may be truncated in the log, e.g.
// "executing "main" at <$scaled.SRelPermalin...>: can't evaluate field SRelPermalink in type *resource.Image"
var identifiersRe = regexp.MustCompile(`at \<(.*?)(\.{3})?\>:`)
func (t *TemplateAdapter) extractIdentifiers(line string) []string {
m := identifiersRe.FindAllStringSubmatch(line, -1)
identifiers := make([]string, len(m))
for i := 0; i < len(m); i++ {
identifiers[i] = m[i][1]
}
return identifiers
}
func (t *TemplateAdapter) addFileContext(name string, inerr error) error {
if strings.HasPrefix(t.Name(), "_internal") {
return inerr
}
f, realFilename, err := t.fileAndFilename(t.Name())
if err != nil {
return inerr
}
defer f.Close()
master, hasMaster := t.NameBaseTemplateName[name]
ferr := errors.Wrap(inerr, "execute of template failed")
// Since this can be a composite of multiple template files (single.html + baseof.html etc.)
// we potentially need to look in both -- and cannot rely on line number alone.
lineMatcher := func(m herrors.LineMatcher) bool {
if m.Position.LineNumber != m.LineNumber {
return false
}
if !hasMaster {
return true
}
identifiers := t.extractIdentifiers(m.Error.Error())
for _, id := range identifiers {
if strings.Contains(m.Line, id) {
return true
}
}
return false
}
fe, ok := herrors.WithFileContext(ferr, realFilename, f, lineMatcher)
if ok || !hasMaster {
return fe
}
// Try the base template if relevant
f, realFilename, err = t.fileAndFilename(master)
if err != nil {
return err
}
defer f.Close()
fe, ok = herrors.WithFileContext(ferr, realFilename, f, lineMatcher)
if !ok {
// Return the most specific.
return ferr
}
return fe
}
func (t *TemplateAdapter) fileAndFilename(name string) (afero.File, string, error) {
fs := t.Fs
filename := filepath.FromSlash(name)
fi, err := fs.Stat(filename)
if err != nil {
return nil, "", err
}
fim := fi.(hugofs.FileMetaInfo)
meta := fim.Meta()
f, err := meta.Open()
if err != nil {
return nil, "", errors.Wrapf(err, "failed to open template file %q:", filename)
}
return f, meta.Filename(), nil
}
// ExecuteToString executes the current template and returns the result as a
// string.
func (t *TemplateAdapter) ExecuteToString(data interface{}) (string, error) {
b := bp.GetBuffer()
defer bp.PutBuffer(b)
if err := t.Execute(b, data); err != nil {
return "", err
}
return b.String(), nil
}
// Tree returns the template Parse tree as a string.
// Note: this isn't safe for parallel execution on the same template
// vs Lookup and Execute.
func (t *TemplateAdapter) Tree() string {
var tree *parse.Tree
switch tt := t.Template.(type) {
case *template.Template:
tree = tt.Tree
case *texttemplate.Template:
tree = tt.Tree
default:
panic("Unknown template")
}
if tree == nil || tree.Root == nil {
return ""
}
s := tree.Root.String()
return s
}
// TemplateFuncsGetter allows to get a map of functions.
type TemplateFuncsGetter interface {
GetFuncs() map[string]interface{}
}
// TemplateTestMocker adds a way to override some template funcs during tests.
// The interface is named so it's not used in regular application code.
type TemplateTestMocker interface {
SetFuncs(funcMap map[string]interface{})
}