hugo/resource/postcss/postcss.go

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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
2018-02-20 09:02:14 +00:00
// 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 postcss
import (
"fmt"
"io"
"path/filepath"
"github.com/gohugoio/hugo/hugofs"
"github.com/mitchellh/mapstructure"
// "io/ioutil"
"os"
"os/exec"
"github.com/gohugoio/hugo/common/errors"
"github.com/gohugoio/hugo/resource"
)
// Some of the options from https://github.com/postcss/postcss-cli
type Options struct {
// Set a custom path to look for a config file.
Config string
NoMap bool `mapstructure:"no-map"` // Disable the default inline sourcemaps
// Options for when not using a config file
Use string // List of postcss plugins to use
Parser string // Custom postcss parser
Stringifier string // Custom postcss stringifier
Syntax string // Custom postcss syntax
}
func DecodeOptions(m map[string]interface{}) (opts Options, err error) {
if m == nil {
return
}
err = mapstructure.WeakDecode(m, &opts)
return
}
func (opts Options) toArgs() []string {
var args []string
if opts.NoMap {
args = append(args, "--no-map")
}
if opts.Use != "" {
args = append(args, "--use", opts.Use)
}
if opts.Parser != "" {
args = append(args, "--parser", opts.Parser)
}
if opts.Stringifier != "" {
args = append(args, "--stringifier", opts.Stringifier)
}
if opts.Syntax != "" {
args = append(args, "--syntax", opts.Syntax)
}
return args
}
// Client is the client used to do PostCSS transformations.
type Client struct {
rs *resource.Spec
}
// New creates a new Client with the given specification.
func New(rs *resource.Spec) *Client {
return &Client{rs: rs}
}
type postcssTransformation struct {
options Options
rs *resource.Spec
}
func (t *postcssTransformation) Key() resource.ResourceTransformationKey {
return resource.NewResourceTransformationKey("postcss", t.options)
}
// Transform shells out to postcss-cli to do the heavy lifting.
// For this to work, you need some additional tools. To install them globally:
// npm install -g postcss-cli
// npm install -g autoprefixer
func (t *postcssTransformation) Transform(ctx *resource.ResourceTransformationCtx) error {
const binary = "postcss"
if _, err := exec.LookPath(binary); err != nil {
// This may be on a CI server etc. Will fall back to pre-built assets.
return errors.FeatureNotAvailableErr
}
var configFile string
logger := t.rs.Logger
if t.options.Config != "" {
configFile = t.options.Config
} else {
configFile = "postcss.config.js"
}
configFile = filepath.Clean(configFile)
// We need an abolute filename to the config file.
if !filepath.IsAbs(configFile) {
// We resolve this against the virtual Work filesystem, to allow
// this config file to live in one of the themes if needed.
fi, err := t.rs.BaseFs.Work.Fs.Stat(configFile)
if err != nil {
if t.options.Config != "" {
// Only fail if the user specificed config file is not found.
return fmt.Errorf("postcss config %q not found: %s", configFile, err)
}
configFile = ""
} else {
configFile = fi.(hugofs.RealFilenameInfo).RealFilename()
}
}
var cmdArgs []string
if configFile != "" {
logger.INFO.Println("postcss: use config file", configFile)
cmdArgs = []string{"--config", configFile}
}
if optArgs := t.options.toArgs(); len(optArgs) > 0 {
cmdArgs = append(cmdArgs, optArgs...)
}
cmd := exec.Command(binary, cmdArgs...)
cmd.Stdout = ctx.To
cmd.Stderr = os.Stderr
stdin, err := cmd.StdinPipe()
if err != nil {
return err
}
go func() {
defer stdin.Close()
io.Copy(stdin, ctx.From)
}()
err = cmd.Run()
if err != nil {
return err
}
return nil
}
// Process transforms the given Resource with the PostCSS processor.
func (c *Client) Process(res resource.Resource, options Options) (resource.Resource, error) {
return c.rs.Transform(
res,
&postcssTransformation{rs: c.rs, options: options},
)
}