hugo/tpl/template.go

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// 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
Add Hugo Piper with SCSS support and much more Before this commit, you would have to use page bundles to do image processing etc. in Hugo. This commit adds * A new `/assets` top-level project or theme dir (configurable via `assetDir`) * A new template func, `resources.Get` which can be used to "get a resource" that can be further processed. This means that you can now do this in your templates (or shortcodes): ```bash {{ $sunset := (resources.Get "images/sunset.jpg").Fill "300x200" }} ``` This also adds a new `extended` build tag that enables powerful SCSS/SASS support with source maps. To compile this from source, you will also need a C compiler installed: ``` HUGO_BUILD_TAGS=extended mage install ``` Note that you can use output of the SCSS processing later in a non-SCSSS-enabled Hugo. The `SCSS` processor is a _Resource transformation step_ and it can be chained with the many others in a pipeline: ```bash {{ $css := resources.Get "styles.scss" | resources.ToCSS | resources.PostCSS | resources.Minify | resources.Fingerprint }} <link rel="stylesheet" href="{{ $styles.RelPermalink }}" integrity="{{ $styles.Data.Digest }}" media="screen"> ``` The transformation funcs above have aliases, so it can be shortened to: ```bash {{ $css := resources.Get "styles.scss" | toCSS | postCSS | minify | fingerprint }} <link rel="stylesheet" href="{{ $styles.RelPermalink }}" integrity="{{ $styles.Data.Digest }}" media="screen"> ``` A quick tip would be to avoid the fingerprinting part, and possibly also the not-superfast `postCSS` when you're doing development, as it allows Hugo to be smarter about the rebuilding. Documentation will follow, but have a look at the demo repo in https://github.com/bep/hugo-sass-test New functions to create `Resource` objects: * `resources.Get` (see above) * `resources.FromString`: Create a Resource from a string. New `Resource` transformation funcs: * `resources.ToCSS`: Compile `SCSS` or `SASS` into `CSS`. * `resources.PostCSS`: Process your CSS with PostCSS. Config file support (project or theme or passed as an option). * `resources.Minify`: Currently supports `css`, `js`, `json`, `html`, `svg`, `xml`. * `resources.Fingerprint`: Creates a fingerprinted version of the given Resource with Subresource Integrity.. * `resources.Concat`: Concatenates a list of Resource objects. Think of this as a poor man's bundler. * `resources.ExecuteAsTemplate`: Parses and executes the given Resource and data context (e.g. .Site) as a Go template. Fixes #4381 Fixes #4903 Fixes #4858
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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 {
Add Hugo Piper with SCSS support and much more Before this commit, you would have to use page bundles to do image processing etc. in Hugo. This commit adds * A new `/assets` top-level project or theme dir (configurable via `assetDir`) * A new template func, `resources.Get` which can be used to "get a resource" that can be further processed. This means that you can now do this in your templates (or shortcodes): ```bash {{ $sunset := (resources.Get "images/sunset.jpg").Fill "300x200" }} ``` This also adds a new `extended` build tag that enables powerful SCSS/SASS support with source maps. To compile this from source, you will also need a C compiler installed: ``` HUGO_BUILD_TAGS=extended mage install ``` Note that you can use output of the SCSS processing later in a non-SCSSS-enabled Hugo. The `SCSS` processor is a _Resource transformation step_ and it can be chained with the many others in a pipeline: ```bash {{ $css := resources.Get "styles.scss" | resources.ToCSS | resources.PostCSS | resources.Minify | resources.Fingerprint }} <link rel="stylesheet" href="{{ $styles.RelPermalink }}" integrity="{{ $styles.Data.Digest }}" media="screen"> ``` The transformation funcs above have aliases, so it can be shortened to: ```bash {{ $css := resources.Get "styles.scss" | toCSS | postCSS | minify | fingerprint }} <link rel="stylesheet" href="{{ $styles.RelPermalink }}" integrity="{{ $styles.Data.Digest }}" media="screen"> ``` A quick tip would be to avoid the fingerprinting part, and possibly also the not-superfast `postCSS` when you're doing development, as it allows Hugo to be smarter about the rebuilding. Documentation will follow, but have a look at the demo repo in https://github.com/bep/hugo-sass-test New functions to create `Resource` objects: * `resources.Get` (see above) * `resources.FromString`: Create a Resource from a string. New `Resource` transformation funcs: * `resources.ToCSS`: Compile `SCSS` or `SASS` into `CSS`. * `resources.PostCSS`: Process your CSS with PostCSS. Config file support (project or theme or passed as an option). * `resources.Minify`: Currently supports `css`, `js`, `json`, `html`, `svg`, `xml`. * `resources.Fingerprint`: Creates a fingerprinted version of the given Resource with Subresource Integrity.. * `resources.Concat`: Concatenates a list of Resource objects. Think of this as a poor man's bundler. * `resources.ExecuteAsTemplate`: Parses and executes the given Resource and data context (e.g. .Site) as a Go template. Fixes #4381 Fixes #4903 Fixes #4858
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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
}
Add Hugo Piper with SCSS support and much more Before this commit, you would have to use page bundles to do image processing etc. in Hugo. This commit adds * A new `/assets` top-level project or theme dir (configurable via `assetDir`) * A new template func, `resources.Get` which can be used to "get a resource" that can be further processed. This means that you can now do this in your templates (or shortcodes): ```bash {{ $sunset := (resources.Get "images/sunset.jpg").Fill "300x200" }} ``` This also adds a new `extended` build tag that enables powerful SCSS/SASS support with source maps. To compile this from source, you will also need a C compiler installed: ``` HUGO_BUILD_TAGS=extended mage install ``` Note that you can use output of the SCSS processing later in a non-SCSSS-enabled Hugo. The `SCSS` processor is a _Resource transformation step_ and it can be chained with the many others in a pipeline: ```bash {{ $css := resources.Get "styles.scss" | resources.ToCSS | resources.PostCSS | resources.Minify | resources.Fingerprint }} <link rel="stylesheet" href="{{ $styles.RelPermalink }}" integrity="{{ $styles.Data.Digest }}" media="screen"> ``` The transformation funcs above have aliases, so it can be shortened to: ```bash {{ $css := resources.Get "styles.scss" | toCSS | postCSS | minify | fingerprint }} <link rel="stylesheet" href="{{ $styles.RelPermalink }}" integrity="{{ $styles.Data.Digest }}" media="screen"> ``` A quick tip would be to avoid the fingerprinting part, and possibly also the not-superfast `postCSS` when you're doing development, as it allows Hugo to be smarter about the rebuilding. Documentation will follow, but have a look at the demo repo in https://github.com/bep/hugo-sass-test New functions to create `Resource` objects: * `resources.Get` (see above) * `resources.FromString`: Create a Resource from a string. New `Resource` transformation funcs: * `resources.ToCSS`: Compile `SCSS` or `SASS` into `CSS`. * `resources.PostCSS`: Process your CSS with PostCSS. Config file support (project or theme or passed as an option). * `resources.Minify`: Currently supports `css`, `js`, `json`, `html`, `svg`, `xml`. * `resources.Fingerprint`: Creates a fingerprinted version of the given Resource with Subresource Integrity.. * `resources.Concat`: Concatenates a list of Resource objects. Think of this as a poor man's bundler. * `resources.ExecuteAsTemplate`: Parses and executes the given Resource and data context (e.g. .Site) as a Go template. Fixes #4381 Fixes #4903 Fixes #4858
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// 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 ""
}
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// 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 {
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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"
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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
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}
// 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{})
}