Before this commit you would typically use `.Scratch.Add` to manually create slices in a loop.
With variable overwrite in Go 1.11, we can do better. This commit adds the `append` template func.
A made-up example:
```bash
{{ $p1 := index .Site.RegularPages 0 }}{{ $p2 := index .Site.RegularPages 1 }}
{{ $pages := slice }}
{{ if true }}
{{ $pages = $pages | append $p2 $p1 }}
{{ end }}
```
Note that with 2 slices as arguments, the two examples below will give the same result:
```bash
{{ $s1 := slice "a" "b" | append (slice "c" "d") }}
{{ $s2 := slice "a" "b" | append "c" "d" }}
```
Both of the above will give `[]string{a, b, c, d}`.
This commit also improves the type handling in the `slice` template function. Now `slice "a" "b"` will give a `[]string` slice. The old behaviour was to return a `[]interface{}`.
Fixes#5190
Hugo Pipes added minification support for resources fetched via ´resources.Get` and similar.
This also adds support for minification of the final output for supported output formats: HTML, XML, SVG, CSS, JavaScript, JSON.
To enable, run Hugo with the `--minify` flag:
```bash
hugo --minify
```
This commit is also a major spring cleaning of the `transform` package to allow the new minification step fit into that processing chain.
Fixes#1251
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#4381Fixes#4903Fixes#4858
