hugo/tpl/os/os.go
Bjørn Erik Pedersen dea71670c0
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
2018-07-06 11:46:12 +02:00

132 lines
3.6 KiB
Go

// Copyright 2017 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 os
import (
"errors"
"fmt"
_os "os"
"github.com/gohugoio/hugo/deps"
"github.com/spf13/afero"
"github.com/spf13/cast"
)
// New returns a new instance of the os-namespaced template functions.
func New(deps *deps.Deps) *Namespace {
// Since Hugo 0.38 we can have multiple content dirs. This can make it hard to
// reason about where the file is placed relative to the project root.
// To make the {{ readFile .Filename }} variant just work, we create a composite
// filesystem that first checks the work dir fs and then the content fs.
var rfs afero.Fs
if deps.Fs != nil {
rfs = deps.Fs.WorkingDir
if deps.PathSpec != nil && deps.PathSpec.BaseFs != nil {
rfs = afero.NewReadOnlyFs(afero.NewCopyOnWriteFs(deps.PathSpec.BaseFs.Content.Fs, deps.Fs.WorkingDir))
}
}
return &Namespace{
readFileFs: rfs,
deps: deps,
}
}
// Namespace provides template functions for the "os" namespace.
type Namespace struct {
readFileFs afero.Fs
deps *deps.Deps
}
// Getenv retrieves the value of the environment variable named by the key.
// It returns the value, which will be empty if the variable is not present.
func (ns *Namespace) Getenv(key interface{}) (string, error) {
skey, err := cast.ToStringE(key)
if err != nil {
return "", nil
}
return _os.Getenv(skey), nil
}
// readFile reads the file named by filename in the given filesystem
// and returns the contents as a string.
// There is a upper size limit set at 1 megabytes.
func readFile(fs afero.Fs, filename string) (string, error) {
if filename == "" {
return "", errors.New("readFile needs a filename")
}
if info, err := fs.Stat(filename); err == nil {
if info.Size() > 1000000 {
return "", fmt.Errorf("File %q is too big", filename)
}
} else {
return "", err
}
b, err := afero.ReadFile(fs, filename)
if err != nil {
return "", err
}
return string(b), nil
}
// ReadFile reads the file named by filename relative to the configured WorkingDir.
// It returns the contents as a string.
// There is an upper size limit set at 1 megabytes.
func (ns *Namespace) ReadFile(i interface{}) (string, error) {
s, err := cast.ToStringE(i)
if err != nil {
return "", err
}
return readFile(ns.readFileFs, s)
}
// ReadDir lists the directory contents relative to the configured WorkingDir.
func (ns *Namespace) ReadDir(i interface{}) ([]_os.FileInfo, error) {
path, err := cast.ToStringE(i)
if err != nil {
return nil, err
}
list, err := afero.ReadDir(ns.deps.Fs.WorkingDir, path)
if err != nil {
return nil, fmt.Errorf("Failed to read Directory %s with error message %s", path, err)
}
return list, nil
}
// FileExists checks whether a file exists under the given path.
func (ns *Namespace) FileExists(i interface{}) (bool, error) {
path, err := cast.ToStringE(i)
if err != nil {
return false, err
}
if path == "" {
return false, errors.New("fileExists needs a path to a file")
}
status, err := afero.Exists(ns.readFileFs, path)
if err != nil {
return false, err
}
return status, nil
}