# `jekyll_plugin_support` [](https://badge.fury.io/rb/jekyll_plugin_support)
After writing over two dozen Jekyll plugins, I distilled the common code into `Jekyll_plugin_support`.
This F/OSS Ruby gem facilitates writing and testing Jekyll plugins and handles the standard housekeeping that every Jekyll
inline and block tag plugin requires.
Logging, parsing arguments, obtaining references to site and page objects, etc. are all handled.
The result is faster Jekyll plugin writing with fewer bugs.
`Jekyll_plugin_support` can be used to create simple Jekyll plugins in
the `_plugins/` directory of your Jekyll project, or gem-based Jekyll plugins.
At present, only Jekyll tags and blocks are supported.
Public plugins that use `jekyll_plugin_support` include:
... and also the demonstration plugins in
[`jekyll_plugin_support`](https://github.com/mslinn/jekyll_plugin_support/tree/master/demo/_plugins)
## Features
Jekyll plugin tags created from `jekyll_plugin_support` framework automatically have the following features:
1. Boilerplate is removed, so you can focus on the required logic and output.
2. Arguments are parsed for keywords and name/value parameters.
3. Single or double quotes can be used for arguments and parameters.
4. Important variables are predefined.
5. Error handling is standardized, and includes an automatically defined error type
and corresponding CSS tag for each Jekyll tag.
6. Jekyll and Liquid variables, including `layout`, `page` and `include` variables,
can be passed as parameters to tags, and used in the body of block tags.
7. Plugin registration is integrated, and important configuration details are reported during registration.
8. A custom logger is created for each tag, independent of the default Jekyll logger.
9. Variables can be defined in `_config.yml`, and optionally have different values for debug mode,
production mode and test mode.
10. An attribution message is available.
11. Draft pages are automatically detected.
12. A demonstration website is provided for easy testing of every plugin.
13. Visual Studio Code debugging is set up for the plugin code and the demo website.
14. Plugins can be subclassed.
15. [`Nugem`](https://mslinn.com/ruby/6800-nugem.html) can create working scaffolding for new plugins built
using `jekyll_plugin_support`.
16. Four new attributes are added to
[`site`](https://jekyllrb.com/docs/variables/#site-variables):
a. `all_collections` includes all documents in all collections.
b. `all_documents` includes `all_collections` plus all standalone pages.
c. `everything` includes `all_documents` plus all static files.
d. `sorted_lru_files` is used by a new binary search lookup for matching page suffixes.
The `jekyll_href` and `jekyll_draft` plugins use this feature.
## Installation
### For A Jekyll Website
`Jekyll_plugin_support` is packaged as a Ruby gem.
If you want to write a custom Jekyll plugin that will reside in a Jekyll project’s `_plugins` directory,
add the following line to your Jekyll plugin’s `Gemfile`.
```ruby
group :jekyll_plugins do
# ...
gem 'jekyll_plugin_support', '>= 1.1.0'
# ...
end
```
Run the standard `jekyll_plugin_support` setup procedure:
```shell
$ bin/setup
```
### As a Gem Dependency
If your custom plugin will be packaged into a gem, add the following to your plugin’s `.gemspec`:
```ruby
Gem::Specification.new do |spec|
# ...
spec.add_dependency 'jekyll_plugin_support', '>= 1.1.0'
# ...
end
```
Install the `jekyll_plugin_support` gem into your plugin project in the usual manner:
```shell
$ bundle
```
Copy the CSS classes from
[`demo/assets/css/jekyll_plugin_support.css`](demo/assets/css/jekyll_plugin_support.css)
to your Jekyll project’s CSS file.
## About `jekyll_plugin_support`
This Jekyll plugin includes a generator,
triggered by a high-priority hook, and a block tag called `all_collections`.
`JekyllSupport::JekyllBlock` and `JekyllSupport::JekyllTag`
provide support for [Jekyll tag block plugins](https://jekyllrb.com/docs/plugins/tags/#tag-blocks)
and [Jekyll inline tag plugins](https://jekyllrb.com/docs/plugins/tags/), respectively.
They are very similar in construction and usage.
Instead of subclassing your custom Jekyll block tag class from `Liquid::Block`,
subclass from `JekyllSupport::JekyllBlock`.
Similarly, instead of subclassing your custom Jekyll tag class from `Liquid::Tag`,
subclass from `JekyllSupport::JekyllTag`.
Both JekyllSupport classes instantiate new instances of
[`PluginMetaLogger`](https://github.com/mslinn/jekyll_plugin_logger) (called `@logger`) and
[`JekyllPluginHelper`](https://github.com/mslinn/jekyll_plugin_support/blob/master/lib/jekyll_plugin_support_helper.rb)
(called `@helper`).
`JekyllPluginHelper` defines a generic initialize method, and your tag or block tag class should not need to override it.
Also, your tag or block tag class should not define a method called render, because `jekyll_plugin_support` defines one.
Instead, define a method called `render_impl`.
For inline tags, `render_impl` does not accept any parameters.
For block tags, a single parameter is required, which contains text passed from your block in the page.
Your implementation of render_impl can parse parameters passed to your tag, as described in
[Tag Parameter Parsing](http://mslinn.com/jekyll/10100-jekyll-plugin-background.html#params).
In addition, within render_impl,
the arguments passed to the tag will have been tokenized and parsed,
with Jekyll and Liquid variables substituted for their values,
and all the public Jekyll variables will be available as instance variables.
Error handling will also have been set up,
and access to your tag's entry within _config.yml will have been set up.
## General Usage
Please see the [`demo/`](demo/) project for a well-documented set of demonstration Jekyll plugins built from `jekyll_plugin_support`.
Additional information is available [here](https://mslinn.com/jekyll/10200-jekyll-plugin-background.html) and the
[`jekyll_plugin_support`](https://www.mslinn.com/jekyll_plugins/jekyll_plugin_support.html) documentation.
[`JekyllSupport::JekyllBlock`](https://github.com/mslinn/jekyll_plugin_support/blob/master/lib/jekyll_plugin_support_block.rb) and
[`JekyllSupport::JekyllTag`](https://github.com/mslinn/jekyll_plugin_support/blob/master/lib/jekyll_plugin_support_tag.rb) provide
support for Jekyll block tags and Jekyll inline tags, respectively.
They are similar in construction and usage.
Instead of subclassing your Jekyll block tag class from `Liquid::Block`,
subclass from `JekyllSupport::JekyllBlock` instead.
Likewise, instead of subclassing your Jekyll inline tag class from `Liquid::Tag`,
subclass from `JekyllSupport::JekyllTag` instead.
Both `JekyllSupport` classes instantiate new instances of
[`PluginMetaLogger`](https://github.com/mslinn/jekyll_plugin_logger) (called `@logger`) and
[`JekyllPluginHelper`](lib/jekyll_plugin_helper.rb) (called `@helper`).
### Inline and Block Tag Plugin Implementation
Both `JekyllSupport` classes define a generic `initialize` method,
and your inline tag or block tag class should not override it.
Also, your inline tag or block tag class should not define a method called `render`,
because both `JekyllSupport` classes define this method.
Instead, define a method called `render_impl`.
For inline tags, `render_impl` does not accept any parameters.
For block tags, a single parameter is required, which receives any text enclosed within your block by the website author.
### New `Site` Attributes
No explicit initialization or setup is required.
Jekyll plugins can access the value of
`site.all_collections`, `site.all_documents` and `site.everything`;
however, Liquid code in Jekyll pages and documents cannot.
### Excluding Files
There are two ways to exclude files from the new `site` attributes.
1) The [`exclude` entry in `_config.yml`](https://jekyllrb.com/docs/configuration/options#global-configuration)
can be used as it normally would.
2) Adding the following entry to a page’s front matter causes that page to be excluded
from the collection created by this plugin:
```html
---
exclude_from_all: true
---
```
### `all_collections` Plugin Usage
Jekyll generators and tags receive an enhanced version of the `site` Jekyll variable.
#### From a Custom Plugin
In the following example of how to use the `all_collections` plugin in a custom plugin,
the `do_something_with` function processes all `Jekyll::Page`s, `Jekyll:Document`s, and static files.
```ruby
@site.everything.each do |apage|
do_something_with apage
end
```
#### Using the Block Tag
The general form of the Jekyll tag, including all options, is:
```html
{% all_collections
date_column='date|last_modified'
heading='All Posts'
id='asdf'
sort_by='SORT_KEYS'
%}
```
##### `date_column` Attribute
One of two date columns can be displayed in the generated HTML:
either `date` (when the article was originally written),
or `last_modified`.
The default value for the `date_column` attribute is `date`.
##### `heading` Attribute
If no `heading` attribute is specified, a heading will automatically be generated, which contains the `sort_by` values,
for example:
```html
{% all_collections id='abcdef' sort_by="last_modified" %}
```
The above generates a heading like:
```html
All Posts Sorted By last_modified
```
To suppress both a `h2` heading (and the enclosed `id`) from being generated,
specify an empty string for the value of `heading`:
```html
{% all_collections heading='' %}
```
##### `id` Attribute
If your Jekyll layout employs [`jekyll-toc`](https://github.com/allejo/jekyll-toc), then `id` attributes are important.
The `jekyll-toc` include checks for `id` attributes in `h2` ... `h6` tags, and if found,
and if the attribute value is enclosed in double quotes
(`id="my_id"`, not single quotes like `id='my_id'`),
then the heading is included in the table of contents.
To suppress an `id` from being generated,
and thereby preventing the heading from appearing in the automatically generated table of contents from `jekyll-toc`,
specify an empty string for the value of `id`, like this:
```html
{% all_collections id='' %}
```
##### `SORT_KEYS` Values
`SORT_KEYS` specifies how to sort the collection.
Values can include one or more of the following attributes:
`date`, `destination`, `draft`, `label`, `last_modified`, `last_modified_at`, `path`, `relative_path`,
`title`, `type`, and `url`.
Ascending sorts are the default; however, a descending sort can be achieved by prepending `-` before an attribute.
To specify more than one sort key, provide a comma-delimited string of values.
Included spaces are ignored.
For example, specify the primary sort key as `draft`,
the secondary sort key as `last_modified`,
and the tertiary key as `label`:
```html
{% all_collections
date_column='last_modified'
heading='All Posts'
id='asdf'
sort_by='draft, last_modified, label'
%}
```
#### Liquid Usage Examples
Here is a short Jekyll page, including front matter,
demonstrating this plugin being invoked with all default attribute values:
```html
---
description: "
Dump of all collections, sorted by date originally written, newest to oldest.
The heading text will be All Posts Sorted By -date
"
layout: default
title: Testing, 1, 2, 3
---
{% all_collections %}
```
Following are examples of how to specify the sort parameters.
**Explicitly express the default sort**
(sort by the date originally written, newest to oldest):
```html
{% all_collections sort_by="-date" %}
```
Sort by date, from oldest to newest:
```html
{% all_collections sort_by="date" %}
```
**Sort by the date last modified, oldest to newest:**
```html
{% all_collections sort_by="last_modified" %}
```
**Sort by the date last modified, newest to oldest:**
```html
{% all_collections sort_by="-last_modified" %}
```
**Several attributes can be specified as sort criteria**
by passing them as a comma-delimited string.
Included spaces are ignored:
```html
{% all_collections sort_by="-last_modified, -date" %}
{% all_collections sort_by="-last_modified, title" %}
{% all_collections sort_by="-last_modified, -date, title" %}
```
**The following two examples produce the same output:**
```html
{% all_collections sort_by="-last_modified,-date" %}
{% all_collections sort_by="-last_modified, -date" %}
```
## Predefined Plugin Variables
`Jekyll_plugin_support` defines the following Ruby variables that you can use in your plugin’s `render_impl` method:
* `@argument_string` Unparsed markup passed as a parameter to your block tag and inline tag.
* `@argv` returns any remaining tokens after `parameter_specified?` has been invoked.
* [`@attribution`](#subclass-attribution) Attribution markup
* [`@config`](https://docs.github.com/en/pages/setting-up-a-github-pages-site-with-jekyll/about-github-pages-and-jekyll#configuring-jekyll-in-your-github-pages-site)
The [YAML](https://yaml.org/) Jekyll site configuration file
* [`@helper`](https://github.com/mslinn/jekyll_plugin_support/blob/master/lib/jekyll_plugin_helper.rb)
`JekyllPluginHelper` instance for your plugin.
* [`@layout`](https://jekyllrb.com/docs/variables/#global-variables) Layout information
* `@logger` [`jekyll_plugin_logger`](https://github.com/mslinn/jekyll_plugin_logger) instance for your Jekyll plugin.
* [`@mode`](https://jekyllrb.com/docs/configuration/environments/)
Indicates `production`, `test` or `development` mode.
* [`@page`](https://jekyllrb.com/docs/variables/#page-variables) `Jekyll::Page` variables
* [`@paginator`](https://jekyllrb.com/docs/variables/#page-variables) Pagination variables
* [`@scopes`](https://jekyllrb.com/docs/variables/)
See the [`jekyll_plugin_support` demo project](demo/variables.html)
* [`@site`](https://jekyllrb.com/docs/variables/#site-variables) Site variables
* [`@tag_config`](lib/jekyll_plugin_support_tag.rb)
Contents of the section of `_config.yml` named after your plugin.
* `@tag_name` Name of your Jekyll block tag or inline tag plugin.
* [`@theme`](https://jekyllrb.com/docs/variables/#global-variables) Theme variables
* `text` Content provided to your block tag.
## Argument Parsing
Tag arguments can be obtained within `render_impl`.
Both keyword options and name/value parameters are supported.
Both `JekyllTag` and `JekyllBlock` use the standard Ruby mechanism for parsing command-line options:
[`shellwords`](https://ruby-doc.org/stdlib-2.5.1/libdoc/shellwords/rdoc/Shellwords.html) and
[`key_value_parser`](https://www.rubydoc.info/gems/key-value-parser).
All your code has to do is to specify the keywords to search for in the string
passed from the HTML page that your tag is embedded in.
The included `demo` website has examples;
both [`demo/_plugins/demo_inline_tag.rb`](demo/_plugins/demo_inline_tag.rb) and
[`demo/_plugins/demo_block_tag.rb`](demo/_plugins/demo_block_tag.rb) contain the following:
```ruby
@keyword1 = @helper.parameter_specified? 'keyword1'
@keyword2 = @helper.parameter_specified? 'keyword2'
@name1 = @helper.parameter_specified? 'name1'
@name2 = @helper.parameter_specified? 'name2'
```
If an argument has a variable reference in it, the value of the variable is substituted for the reference.
For example, given:
* `_layouts/default.html` defines a variable called `var_layout` in its front matter.
* `index.html` defines a variable called `var_page` in its front matter.
* `index.html` assigns a variable called `x` via the liquid `assign` statement.
... then the following references in a page will be substituted for their values in arguments and in block tag bodies:
```html
{% my_block_tag
param1="x={{x}}"
param2="var_page={{page.var_page}}"
param3="var_layout={{layout.var_layout}}"
%}
Assigned variables do not need a namespace: x={{x}}
Page variables must be qualified with the 'page' namespace:
var_page={{page.var_page}}
Layout variables must be qualified with the 'layout' namespace:
var_layout={{layout.var_layout}}
{% endmy_block_tag %}
```
You can see similar code in [`demo/demo_inline_tag.html`](demo/demo_inline_tag.html).
The `page['excerpt']` and `page['output']` key/value pairs are removed from processing because of recursion issues.
You cannot look up those values from a `jekyll_plugin_support` plugin.
### Keyword Options
For all keyword options, values specified in the document _may_ be provided.
If a value is not provided, the value `true` is assumed.
Otherwise, if a value is provided, it _must_ be wrapped in single or double quotes.
### Examples
The following examples use the `die_if_error` keyword option for the
[`pre`](https://www.mslinn.com/jekyll_plugins/jekyll_pre.html#tag) and
[`exec`](https://www.mslinn.com/jekyll_plugins/jekyll_pre.html#tag_exec)
tags from the [`jekyll_pre`](https://www.mslinn.com/jekyll_plugins/jekyll_pre.html) plugin %}.
#### Specifying Tag Option Values
The following sets `die_if_error` `true`:
```html
{% pre die_if_error %} ... {% endpre %}
```
The above is the same as writing:
```html
{% pre die_if_error='true' %} ... {% endpre %}
```
Or writing:
```html
{% pre die_if_error="true" %} ... {% endpre %}
```
Neglecting to provide surrounding quotes around the provided value causes the parser to not recognize the option.
Instead, what you had intended to be the keyword/value pair will be parsed as part of the command.
For the `pre` tag, this means the erroneous string becomes part of the `label` value,
unless `label` is explicitly specified.
For the `exec` tag, this means the erroneous string becomes part of the command to execute.
The following demonstrates the error.
```html
{% pre die_if_error=false %} ... {% endpre %}
```
The above causes the label to be `die_if_error=false`.
```html
{% exec die_if_error=false ls %} ... {% endpre %}
```
The above causes the command to be executed to be `die_if_error=false ls` instead of `ls`.
### Quoting
Parameter values can be quoted.
If the value consists of only one token then quoting is optional.
The following name/value parameters all have the same result:
* `pay_tuesday="true"`
* `pay_tuesday='true'`
* `pay_tuesday=true`
* `pay_tuesday`
If the values consist of more than one token, quotes must be used.
The following examples both yield the same result:
* `pay_tuesday="maybe not"`
* `pay_tuesday='maybe not'`
### Remaining Markup
After your plugin has parsed all the keyword options and name/value parameters,
call `@helper.remaining_markup` to obtain the remaining markup that was passed to your plugin.
## Configuration Variables
`jekyll_plugin_support` provides support for
[Liquid variables](https://shopify.github.io/liquid/tags/variable/)
to be defined in `_config.yml`, in a section called `liquid_vars`.
These variables behave exactly like Liquid variables defined by `assign` and `capture` expressions,
except they are global in scope; these variables are available in every Jekyll web page.
The following `_config.yml` fragment defines 3 variables called `var1`, `var2` and `var3`:
```yaml
liquid-vars:
var1: value1
var2: 'value 2'
var3: value3
```
Liquid variables defined in this manner are intended to be embedded in a webpage.
They are can be used like any other Liquid variable.
## Variable Expansion
Jekyll expands Liquid variable references during the page rendering process.
Jekyll does not expand Liquid variable references passes as parameters to tag and block plugins, however.
However, plugins made from `jekyll_plugin_support` automatically
expand all types of variable references passed as parameters and in block tag bodies.
`Jekyll_plugin_support` tag and block plugins expand the following types of variables:
* Jekyll_plugin_support configuration variables, discussed above.
* Jekyll [page](https://jekyllrb.com/docs/variables/#page-variables) and
[layout](https://jekyllrb.com/docs/layouts/#variables) variables.
* Inline Liquid variables (defined in [assign](https://shopify.dev/docs/api/liquid/tags/assign) and [capture](https://shopify.dev/docs/api/liquid/tags/capture) statements).
In the following example web page, Jekyll expands the `var1` reference within the `` tag,
but not the `var1` or `var2` references passed to `my_plugin`.
```html
This is the value of var1: {{var1}}.
{% my_plugin param1="{{var1}}" param2="{{var2}}" %}
```
Assuming that `my_plugin` was written as a `jekyll_plugin_support` plugin,
all variable references in its parameters are expanded.
Thus, the above is interpreted as follows when `my_plugin` is evaluated during the Jekyll rendering process:
```html
This is the value of var1: value1.
{% my_plugin param1="value1" param2="value 2" %}
```
`Jekyll_plugin_support` expands most of the [plugin variables described above](#predefined-variables),
replacing Liquid variable references with their values.
The exception is `@argument_string`, which is not expanded.
### Liquid Variable Values Specific To Production And Development Modes
`jekyll_plugin_support` allows Liquid variables defined in `_config.yml` to have different values
when Jekyll is running in `development`, `production` and `test` modes.
When injecting variables into your Jekyll website, `Jekyll_plugin_support`
refers to definitions specific to the current environment,
and then refers to other definitions that are not overridden.
Here is an example:
```yaml
liquid-vars:
development:
var1: 'http://localhost:4444/demo_block_tag.html'
var2: 'http://localhost:4444/demo_inline_tag.html'
production:
var1: 'https://github.com/django/django/blob/3.1.7'
var2: 'https://github.com/django-oscar/django-oscar/blob/3.0.2'
var3: 'https://github.com/mslinn'
```
For the above, the following variable values are set in `development` mode:
* `var1`: `http://localhost:4444/demo_block_tag.html`
* `var2`: `http://localhost:4444/demo_inline_tag.html`
* `var3`: `https://github.com/mslinn`
... and the following variable values are set in `production` and `test` modes:
* `var1`: `https://github.com/django/django/blob/3.1.7`
* `var2`: `https://github.com/django-oscar/django-oscar/blob/3.0.2`
* `var3`: `https://github.com/mslinn`
### Liquid Variables in `jekyll_plugin_support` Subclasses
You can define additional Liquid variables in plugins built using `jekyll_plugin_support`.
To do this, make entries in `_config.yml` under a key named after the value of `@tag_name`.
For example, let’s imagine you create a plugin using `jekyll_plugin_support`,
and hou register it with the name `phonetic_alphabet`.
You could define Liquid variables that would be made available to content pages in web applications that
incorporate the `phonetic_alphabet` plugin.
The following section in `_config.yml` defines variables called `x`, `y` and `z`,
with values `xray`, `yankee` and `zulu`, respectively:
```yaml
phonetic_alphabet:
x: xray
y: yankee
z: zulu
```
The above definitions allow you to write content pages that use those variables, like the following page containing markup:
```html
---
layout: default
title: Variable demo
---
The letter `x` is pronounced {{x}}.
Similarly, the letters `y` and `z` are pronounced {{y}} and {{z}}.
```
### Evaluating Include Variables
This information is only useful if a plugin might be executed from within an included file.
While Liquid handles regular variables, Jekyll has special handling for variables defined by include parameters.
For example, the following defines a variable in the `include` scope called `var1`
when processing the body of an included file:
```html
{% include myfile.html var1='value1' %}
```
You can obtain the value of this variable from the `render_impl` method of a
`JekyllSupport::JekyllTag` or `JekyllSupport::JekyllBlock` subclass as follows:
```ruby
@var1 = @scopes.first['include']&.[]('var1')
```
## Automatically Created Error Classes
`JekyllSupport::JekyllBlock` and `JekyllSupport::JekyllTag` subclasses
automatically create error classes, named after the subclass.
For example, if you create a `JekyllSupport::JekyllBlock` subclass called `DemoBlockTag`,
the automatically generated error class will be called `DemoBlockTagError`.
Although you could use it as you would any other error class, `JekyllPluginSupport`
provides additional helper methods.
These methods fill in the page path and line number that caused the error, shorten the stack trace,
log an error message, and can be used to return an HTML-friendly version of the message to the web page.
The following example is a shortened version of `demo/_plugins/demo_block_tag.rb`.
You might want to write similar code in your `rescue` blocks.
```ruby
class DemoBlock < JekyllSupport::JekyllBlock
VERSION = '0.1.2'.freeze
def render_impl(text)
raise DemoBlockTagError, 'Fall down, go boom.'
rescue DemoBlockTagError => e
@logger.error e.logger_message
exit! 1 if @die_on_demo_block_error
e.html_message
end
end
```
Error class methods have been provided for standardized and convenient error handling:
* `shorten_backtrace` - most of the lines that spew from a Jekyll backtrace are uninteresting.
* `logger_message` - The message is constructed from the string provided when the error was raised,
with the page path and line number added.
* `html_message` - The same as `logger_message`, but constructed with HTML.
## Self-Reporting Upon Registration
When each tag is registered, it self-reports, for example:
```text
INFO PluginMetaLogger: Loaded plugin demo_inline_tag v0.1.2. It has:
Error class: DemoTagError
CSS class for error messages: demo_tag_error
_config.yml contains the following configuration for this plugin:
{"die_on_demo_tag_error"=>false, "die_on_standard_error"=>false}
INFO PluginMetaLogger: Loaded plugin demo_inline_tag_no_arg v0.1.0. It has:
Error class: DemoTagNoArgsError
CSS class for error messages: demo_tag_no_args_error
_config.yml does not contain configuration information for this plugin.
You could add a section containing default values by specifying a section for the tag name,
and an entry whose name starts with `die_on_`, followed by a snake_case version of the error name.
demo_inline_tag_no_arg:
die_on_demo_tag_no_args_error: false
```
## `no_arg_parsing` Optimization
If your tag or block plugin only needs access to the raw arguments passed from the web page,
without tokenization, and you expect that the plugin might be invoked with large amounts of text,
derive your plugin from `JekyllBlockNoArgParsing` or `JekyllTagNoArgParsing`.
## Writing Plugins
The following minimal examples define `VERSION`,
which is important because `JekyllPluginHelper.register` logs that value when registering the plugin.
This is how you would define plugins in the `_plugins` directory
**Boilerplate for an inline tag plugin**
```ruby
require 'jekyll_plugin_support'
module Jekyll
class DemoTag < JekyllSupport::JekyllTag
VERSION = '0.1.0'.freeze
def render_impl
@helper.gem_file __FILE__ # Enables attribution; only works when plugin is a gem
# Your Jekyll plugin logic goes here
end
JekyllPluginHelper.register(self, 'demo_tag')
end
end
```
**Boilerplate for a tag block plugin**
```ruby
require 'jekyll_plugin_support'
module Jekyll
class DemoBlock < JekyllSupport::JekyllBlock
VERSION = '0.1.0'.freeze
def render_impl(text)
@helper.gem_file __FILE__ # Enables attribution; only works when plugin is a gem
# Your Jekyll plugin logic goes here
end
JekyllPluginHelper.register(self, 'demo_block')
end
end
```
If your plugin is packaged as a gem, then you might need to include `version.rb` into the plugin class.
For example, if your version module looks like this:
**lib/my_plugin/version.rb**:
```ruby
module MyPluginVersion
VERSION = '0.5.0'.freeze
end
```
Then your plugin can incorporate the VERSION constant into your plugin like this:
**lib/my_plugin.rb**:
```ruby
require 'jekyll_plugin_support'
require_relative 'my_plugin/version'
module Jekyll
class MyBlock < JekyllSupport::JekyllBlock
include MyPluginVersion
def render_impl(text)
@helper.gem_file __FILE__ # Enables attribution; only works when plugin is a gem
# Your code here
end
JekyllPluginHelper.register(self, 'demo_block')
end
end
```
## Attribution
`JekyllTag` and `JekyllBlock` subclasses of `jekyll_plugin_support` can utilize the `attribution`
option if they are published as a gem.
`JekyllTagNoArgParsing` and `JekyllBlockNoArgParsing` subclasses cannot.
This feature is usually only desired for `JekyllBlock` subclasses.
* When used as a keyword option, a default value is used for the attribution string.
* When used as a name/value option, the attribution string can be specified.
Using the `attribution` option cause subclasses to replace their usual output with HTML that looks like:
```html
```
The `id` attribute is in the sample HTML above is randomized so more than one attribution can appear on a page.
### Attribution Generation
You can decide where you want the attribution string for your Jekyll tag to appear by invoking `@helper.attribute`.
For example, this is how the
[`jekyll_outline` tag](https://github.com/mslinn/jekyll_outline/blob/v1.1.1/lib/outline_tag.rb#L32-L46) generates output:
```html
<<~HEREDOC
#{make_entries(collection)&.join("\n")}
#{@helper.attribute if @helper.attribution}
HEREDOC
```
### Usage
Typical usage for the `attribution` tag is:
```html
{% my_block_tag attribution %}
Content of my_block_tag.
{% endmy_block_tag %}
```
The normal processing of `my_block_tag` is augmented by interpolating the attribution format string,
which is a Ruby-compatible interpolated string.
The default attribution format string is:
```ruby
"Generated by the #{name} #{version} Jekyll plugin, written by #{author} #{date}."
```
Because `jekyll_plugin_suppprt` subclasses are `gem`s, their `gemfile`s define values for
`name`, `version`, `homepage`, and `authors`, as well as many other properties.
The `date` property is obtained from the plugin/gem publishing date.
An alternative attribution string can be specified properties can be output using any of the above properties:
```html
{% my_tag attribution="Generated by the #{name} #{version} Jekyll plugin, written by #{author} #{date}" %}
```
## Subclassing Plugins
Jekyll plugins created using `jekyll_plugin_support` are implemented as Ruby classes.
If you would like to create a version of an existing Jekyll plugin, you will need to subclass the plugin.
In order to do that, you will need to override the plugin name and version, which are defined as constants.
`Jekyll_plugin_support` provides a method that allows
a constant to be redefined, called `redef_without_warning`.
Use it in a subclass like this:
```ruby
redef_without_warning :PLUGIN_NAME, 'my_plugin'.freeze
redef_without_warning :VERSION, '0.1.0'.freeze
```
## Generator
This plugin incorporates a generator, which adds four new attributes to
[`site`](https://jekyllrb.com/docs/variables/#site-variables):
`all_collections`, `all_documents`, `everything`, and `sorted_lru_files`.
These three attributes can be referenced as `site.everything`, `site.all_collections`
and `site.all_documents`.
* `all_collections` includes all documents in all collections.
* `all_documents` includes `all_collections` plus all standalone pages.
* `everything` includes `all_documents` plus all static files.
* `sorted_lru_files` is used by a new binary search lookup for matching page suffixes.
Currently only `jekyll_href` and `jekyll_draft` use this feature.
### Collection Management
Jekyll provides inconsistent attributes for
[`site.pages`](https://jekyllrb.com/docs/pages/),
[`site.posts`](https://jekyllrb.com/docs/posts/) and
[`site.static_files`](https://jekyllrb.com/docs/static-files/).
* While the `url` attributes of items in `site.posts` and `site.pages` start with a slash (/),
`site.static_files` items do not have a `url` attribute.
* Static files have a `relative_path` attribute, which starts with a slash (/),
but although that attribute is also provided in `site.posts` and `site.pages`,
those values do not start with a slash.
* Paths ending with a slash (`/`) imply that a file called `index.html` should be fetched.
* HTML redirect files created by the
[`jekyll-redirect-from`](https://github.com/jekyll/jekyll-redirect-from) Jekyll plugin,
which are included in `site.static_files`, should be ignored.
These inconsistencies mean that combining the standard three collections of files
provided as `site` attributes will create a new collection that is difficult
to process consistently:
```ruby
# This pseudocode creates `oops`, which is problematic to process consistently
oops = site.all_collections + site.pages + site.static_files
```
`oops`, above, is difficult to process because of inconsistencies in the provided attributes
and how the attributes are constructed.
### Solving The Problem
The generator normalizes these inconsistencies by utilizing the `APage` class
and filtering out HTML redirect files.
The `all_collections` collection contains `APage` representations of `site.collections`.
The `all_documents` collection contains `APage` representations of `site.pages`.
The `everything` collection contains `APage` representations of:
```text
# Pseudocode
site.collections + site.pages + site.static_files - HTML_redirect_files
```
## The `APage` Class
The `site.all_collections`, `site.all_documents` and `site.everything` attributes
consist of arrays of [`APage`](lib/hooks/a_page.rb) instances.
The `APage` class has the following attributes:
`content` (HTML or Markdown), `data` (array), `date` (Ruby Date), `description`, `destination`,
`draft` (Boolean), `ext`, `href`, `label`, `last_modified` or `last_modified_at` (Ruby Date),
`layout`, `origin`, `path`, `relative_path`, `tags`, `title`, `type`, and `url`.
* `href` always starts with a slash.
This value is consistent with `a href` values in website HTML.
Paths ending with a slash (`/`) have `index.html` appended so the path specifies an actual file.
* `origin` indicates the original source of the item.
Possible values are `collection`, `individual_page` and `static_file`.
Knowing the origin of each item allows code to process each type of item appropriately.
## `all_collections` Block Tag
The `all_collections` block tag creates a formatted listing of Jekyll files.
The ordering is configurable; by default, the listing is sorted by `date`, newest to oldest.
The `all_collections` tag has a `data_source` parameter that specifies which new property to report on
(`all_collections`, `all_documents`, or `everything`).
## Requirements
All the pages in the Jekyll website must have an implicit date
(for example, all posts are assigned this property by Jekyll),
or an explicit `date` set in front matter, like this:
```html
---
date: 2022-01-01
---
```
If a front matter variable called `last_modified` or `last_modified_at` exists,
its value will be converted to a Ruby `Date`:
```html
---
last_modified: 2023-01-01
---
```
Or:
```html
---
last_modified_at: 2023-01-01
---
```
Otherwise, if `last_modified` or `last_modified_at` is not present in the front matter for a page,
the `date` value will be used last modified date value.
## Development
After checking out the `jekyll_plugin_suppprt` repository, run `bin/setup` to install dependencies.
`bin/console` provides an interactive prompt that allows you to experiment.
To build and install this gem onto your local machine, run:
```shell
$ bundle exec rake install
jekyll_plugin_support 0.1.0 built to pkg/jekyll_plugin_support-0.1.0.gem.
jekyll_plugin_support (0.1.0) installed.
```
Examine the newly built gem:
```shell
$ gem info jekyll_plugin_support
*** LOCAL GEMS ***
jekyll_plugin_support (0.1.0)
Author: Mike Slinn
Homepage:
https://github.com/mslinn/jekyll_plugin_support
License: MIT
Installed at: /home/mslinn/.gems
Provides support for writing Jekyll plugins.
```
### Build and Install Locally
To build and install this gem onto your local machine, run:
```shell
$ bundle exec rake install
jekyll_all_collections 0.3.8 built to pkg/jekyll_all_collections-0.3.8.gem.
jekyll_all_collections (0.3.8) installed.
```
Examine the newly built gem:
```shell
$ gem info jekyll_all_collections
*** LOCAL GEMS ***
jekyll_all_collections (0.3.8)
Author: Mike Slinn
Homepage:
https://www.mslinn.com/jekyll_plugins/jekyll_all_collections.html
License: MIT
Installed at (0.3.8): /home/mslinn/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0
Provides normalized collections and extra functionality for Jekyll websites.
```
### Build and Push to RubyGems
To release a new version:
1. Update the version number in `version.rb`.
2. Add an entry in `CHANGELOG.md` describing the changes since the last release.
3. Commit all changes to git; if you don't the next step might fail with a confusing error message.
4. Run the following:
```shell
$ bundle exec rake release
```
The above creates a git tag for the version, commits the created tag,
and pushes the new `.gem` file to [RubyGems.org](https://rubygems.org).
### Pry Breakpoint On StandardError
A `pry` breakpoint will be set in the `StandardError` handler if `pry_on_standard_error: true`
is set in variable configuration section of `_config.yml`.
For example, if your plugin is called `blah`, enable the breakpoint with the following section:
```yml
blah:
pry_on_standard_error: true
```
## Debugging
You can control the verbosity of log output by adding the following to `_config.yml` in your Jekyll project:
```yaml
plugin_loggers:
AllCollectionsTag::AllCollectionsTag: warn
```
1. First set breakpoints in the Ruby code that interests you.
2. You have several options for initiating a debug session:
1. Use the **Debug Demo** Visual Studio Code launch configuration.
2. Type the `demo/_bin/debug` command, without the `-r` options shown above.
```console
... lots of output as bundle update runs...
Bundle updated!
INFO PluginMetaLogger: Loaded AllCollectionsHooks v0.2.0 :site, :pre_render, :normal hook plugin.
INFO PluginMetaLogger: Loaded DraftFilter plugin.
INFO PluginMetaLogger: Loaded all_collections v0.2.0 tag plugin.
Configuration file: /mnt/_/work/jekyll/my_plugins/jekyll_all_collections/demo/_config.yml
Cleaner: Removing /mnt/_/work/jekyll/my_plugins/jekyll_all_collections/demo/_site...
Cleaner: Removing /mnt/_/work/jekyll/my_plugins/jekyll_all_collections/demo/.jekyll-metadata...
Cleaner: Removing /mnt/_/work/jekyll/my_plugins/jekyll_all_collections/demo/.jekyll-cache...
Cleaner: Nothing to do for .sass-cache.
Fast Debugger (ruby-debug-ide 0.7.3, debase 0.2.5.beta2, file filtering is supported) listens on 0.0.0.0:1234
```
3. Run `bin/attach` and pass the directory name of a Jekyll website that has a suitable script called `_bin/debug`.
The `demo` subdirectory fits this description.
```console
$ bin/attach demo
Successfully uninstalled jekyll_all_collections-0.1.2
jekyll_all_collections 0.1.2 built to pkg/jekyll_all_collections-0.1.2.gem.
jekyll_all_collections (0.1.2) installed.
Fast Debugger (ruby-debug-ide 0.7.3, debase 0.2.4.1, file filtering is supported) listens on 0.0.0.0:1234
```
3. Attach to the debugger process if required.
This git repo includes two [Visual Studio Code launch configurations](./.vscode/launch.json) for this purpose labeled
**Attach rdbg** and **Attach with ruby_lsp**.
4. Point your web browser to http://localhost:4444
If a debugging session terminates abruptly and leaves ports tied up,
run the `demo/_bin/release_port` script.
## Demonstration Plugins and Website
A demo / test website is provided in the [`demo`](demo) directory.
It can be used to debug the plugin or to run freely.
### Examining the Demo Plugins
The following example plugins use
[Ruby’s squiggly heredoc operator](https://ruby-doc.org/core-2.5.0/doc/syntax/literals_rdoc.html#label-Here+Documents) (`<<~`).
The squiggly heredoc operator removes the outermost indentation.
This provides easy-to-read multiline text literals.
**demo/_plugins/demo_tag.rb**:
```ruby
require 'jekyll_plugin_support'
# Use the JekyllSupport module namespace so the self methods are automajically found
module JekyllSupport
DemoInlineTagError = JekyllSupport.define_error
class DemoTag < JekyllTag
VERSION = '0.1.2'.freeze
# JekyllSupport.redef_without_warning 'VERSION', '0.1.2'.freeze
def render_impl
@demo_tag_error = @helper.parameter_specified? 'raise_demo_tag_error'
@keyword1 = @helper.parameter_specified? 'keyword1'
@keyword2 = @helper.parameter_specified? 'keyword2'
@name1 = @helper.parameter_specified? 'name1'
@name2 = @helper.parameter_specified? 'name2'
@standard_error = @helper.parameter_specified? 'raise_standard_error'
if @tag_config
@die_on_demo_tag_error = @tag_config['die_on_demo_tag_error'] == true
@die_on_standard_error = @tag_config['die_on_standard_error'] == true
end
raise DemoInlineTagError, 'This DemoInlineTagError error is expected.' if @demo_tag_error
raise StandardError, 'This StandardError error is expected.' if @standard_error
# _infinity = 1 / 0 if @standard_error # Not required
output
rescue DemoInlineTagError => e # jekyll_plugin_support handles StandardError
@logger.error { e.logger_message }
exit! 1 if @die_on_demo_tag_error
e.html_message
end
private
def output
<<~END_OUTPUT
# jekyll_plugin_support becomes able to perform variable substitution after this variable is defined.
# The value could be updated at a later stage, but no need to add that complexity unless there is a use case.
@argument_string="#{@argument_string}"
@helper.argv=
#{@helper.argv&.join("\n ")}
# Liquid variable name/value pairs
@helper.params=
#{@helper.params&.map { |k, v| "#{k}=#{v}" }&.join("\n ")}
# The keys_values property serves no purpose any more, consider it deprecated
@helper.keys_values=
#{(@helper.keys_values&.map { |k, v| "#{k}=#{v}" })&.join("\n ")}
@layout='#{@layout}'
@page.keys='#{@page.keys}'
remaining_markup='#{@helper.remaining_markup}'
@keyword1='#{@keyword1}'
@keyword2='#{@keyword2}'
@name1='#{@name1}'
@name2='#{@name2}'
END_OUTPUT
end
JekyllPluginHelper.register(self, 'demo_inline_tag')
end
end
```
**demo/_plugins/demo_block.rb**:
```ruby
require 'cgi'
require 'jekyll_plugin_support'
# Use the JekyllSupport module namespace so the self methods are automajically found
module JekyllSupport
DemoBlockError = JekyllSupport.define_error
class DemoBlock < JekyllBlock
VERSION = '0.1.2'.freeze
def render_impl(text)
@demo_block_error = @helper.parameter_specified? 'raise_demo_block_error'
@keyword1 = @helper.parameter_specified? 'keyword1'
@keyword2 = @helper.parameter_specified? 'keyword2'
@name1 = @helper.parameter_specified? 'name1'
@name2 = @helper.parameter_specified? 'name2'
@standard_error = @helper.parameter_specified? 'raise_standard_error'
if @tag_config
@die_on_demo_block_error = @tag_config['die_on_demo_block_error'] == true
@die_on_standard_error = @tag_config['die_on_standard_error'] == true
end
raise DemoBlockTagError, 'This DemoBlockTagError error is expected.' if @demo_block_error
raise StandardError, 'This StandardError error is expected.' if @standard_error
# _infinity = 1 / 0 if @standard_error # Not required
output text
rescue DemoBlockTagError => e # jekyll_plugin_support handles StandardError
@logger.error { e.logger_message }
exit! 1 if @die_on_demo_block_error
e.html_message
end
private
def output(text)
<<~END_OUTPUT
@helper.tag_name=#{@helper.tag_name}
@mode=#{@mode}
# jekyll_plugin_support becomes able to perform variable substitution after this variable is defined.
# The value could be updated at a later stage, but no need to add that complexity unless there is a use case.
@argument_string="#{@argument_string}"
@helper.argv=
#{@helper.argv&.join("\n ")}
# Liquid variable name/value pairs
@helper.params=
#{@helper.params&.map { |k, v| "#{k}=#{v}" }&.join("\n ")}
# The keys_values property serves no purpose any more, consider it deprecated
@helper.keys_values=
#{(@helper.keys_values&.map { |k, v| "#{k}=#{v}" })&.join("\n ")}
@helper.remaining_markup='#{@helper.remaining_markup}'
@envs=#{@envs.keys.sort.join(', ')}
@config['url']='#{@config['url']}'
@site.collection_names=#{@site.collection_names&.sort&.join(', ')}
@page['description']=#{@page['description']}
@page['path']=#{@page['path']}
@keyword1=#{@keyword1}
@keyword2=#{@keyword2}
@name1=#{@name1}
@name2=#{@name2}
text=#{text}
END_OUTPUT
end
JekyllPluginHelper.register(self, 'demo_block_tag')
end
end
```
The following is an example of no_arg_parsing optimization.
```ruby
require 'jekyll_plugin_support'
# Use the JekyllSupport module namespace so the self methods are automajically found
module JekyllSupport
class DemoTagNoArgs < JekyllTagNoArgParsing
VERSION = '0.1.0'.freeze
def render_impl
<<~END_OUTPUT
The raw arguments passed to this DemoTagNoArgs instance are:
#{@argument_string}
END_OUTPUT
end
JekyllPluginHelper.register(self, 'demo_inline_tag_no_arg')
end
end
```
### Run Freely
1. Run from the command line:
```shell
$ demo/_bin/debug -r
```
2. View the generated website,
which might be at [`http://localhost:4444`](http://localhost:4444),
depending on how you configured it.
### Plugin Debugging
1. Set breakpoints in Visual Studio Code.
2. Run the **Debug Demo development** or **Debug Demo production** launch configuration.
Alternatively, you can:
2. Initiate a debug session from the command line by running the `demo/_bin/debug` script:
```shell
$ demo/_bin/debug
Fetching gem metadata from https://rubygems.org/..........
Resolving dependencies...
Fetching public_suffix 5.0.4
Fetching nokogiri 1.15.5 (x86_64-linux)
Installing public_suffix 5.0.4
Installing nokogiri 1.15.5 (x86_64-linux)
Bundle complete! 17 Gemfile dependencies, 96 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.
INFO PluginMetaLogger: Loaded DraftFilter plugin.
INFO PluginMetaLogger: Loaded outline_js v1.2.1 plugin.
INFO PluginMetaLogger: Loaded outline v1.2.1 plugin.
Configuration file: /mnt/f/jekyll_plugin_support/demo/_config.yml
Cleaner: Removing /mnt/f/jekyll_plugin_support/demo/_site...
Cleaner: Removing /mnt/f/jekyll_plugin_support/demo/.jekyll-metadata...
Cleaner: Removing /mnt/f/jekyll_plugin_support/demo/.jekyll-cache...
Cleaner: Nothing to do for .sass-cache.
DEBUGGER: Debugger can attach via TCP/IP (127.0.0.1:37177)
DEBUGGER: wait for debugger connection...
```
3. Once the `DEBUGGER: wait for debugger connection...` message appears,
run the Visual Studio Code launch configuration called **Attach with rdbg**.
4. View the generated website,
which might be at [`http://localhost:4444`](http://localhost:4444),
depending on how you configured it.
### Build and Push to RubyGems
To release a new version:
1. Update the version number in `version.rb`.
2. Add an entry to `CHANGELOG.md` describing the changes since the previous version.
3. Commit all changes to git;
if you don't the next step might fail with an unexplainable error message.
4. Run the following:
```shell
$ bundle exec rake release
```
The above creates a git tag for the version, commits the created tag,
and pushes the new `.gem` file to [RubyGems.org](https://rubygems.org).
## Contributing
1. Fork the project
2. Create a descriptively named feature branch
3. Add your feature
4. Submit a pull request
## License
The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).