Luigi Template
==============

Overview
--------
Simple multi-language string templating library inspired by [Unix
pipes][pipe].

Features:
* Multi-language: Java, JavaScript, PHP, and Ruby.
* Chainable filters, via piping.
* Useful built-in filters.
* Template caching.
* Small: Less than 4k minified (see `luigi-template.min.js`),
* Stand-alone: No external dependencies (no jQuery, etc),
* Compatible: Works in browsers as old as IE9.
* MIT-licensed.

Installation (Java)
-------------------
To generate a stand-alone JAR file, do the following:

    mvn package

The generated JAR file will be available in the `target/` directory.

Installation (JavaScript)
-------------------------
Minify `luigi-template.js` using your minifier of choice, and drop it
into your source tree.  I like [jsmin][], personally:

    jsmin < luigi-template.js > luigi-template-0.5.0.min.js

*Note:* If you are upgrading from a pre-0.5.0 version of Luigi Template,
be sure to include `luigi-compat.js` as well.  See the *Changes in
0.5.0* section below for details.

Installation (PHP)
------------------
### Using [Composer][composer]

    # in your project root
    composer require pablotron/luigi-template:~0.5

Or add it to the `composer.json` for your project, like so:

    "require": {
      "pablotron/luigi-template": "~0.5"
    },

### Manual Installation
The source file for Luigi Template is entirely self-contained, which
means you can embed it directly in your project without using
[Composer][composer] by doing the following:

    # copy file to your project
    cp php/src/Template.php path/to/your/project/
    
    # then, somewhere in your project...
    require_once 'path/to/Template.php';

Installation (Ruby)
-------------------
Install via [RubyGems][]:

    # install luigi-template via ruby gems
    gem install -r luigi-template

Usage (JavaScript)
------------------
A minimal template:

    // create template
    var t = new Luigi.Template('hello %{name}');

    // run template, print result to console
    console.log(t.run({
      name: 'Paul',
    }));

    // prints "hello Paul"

If you have a template that you only need to run one time, you can use
the `Luigi.run()` singleton to run it, like this:

    // create and run template in one shot
    var r = Luigi.run('hello %{name}', {
      name: 'Paul',
    });

    // print result to console
    console.log(r);

    // prints "hello Paul"

Templates parameters can be modified by filters.  Filters are applied to
a parameter value by appending a `|` (pipe) character, followed by the
filter name.

Here is the template from above, with the name value HTML-escaped using
a built-in filter:

    // create template that prints hello and the HTML-escaped name
    var t = new Luigi.Template('hello %{name | h}');

    // run template, print result to console
    console.log(t.run({
      name: '<Paul>',
    }));

    // prints "hello &lt;Paul&gt;"

The built-in templates are:

* `uc`: Upper-case string value.
* `lc`: Lower-case string value.
* `s`: Pluralize a value by returning `""` if the value is 1, and
  `"s"` otherwise.
* `length`: Get the length of an array.
* `trim`: Trim leading and trailing whitespace from a string.
* `h`: HTML-escape a string value.
* `u`: URL-escape a string value.
* `json`: JSON-encode a value.

You can create your own custom filters, too.

The easiest way to create your own custom filter is to add it to the set
of global filters (`Luigi.FILTERS`), like so:

    // add global template filter
    Luigi.FILTERS.barify = function(s) {
      return 'bar-' + s + '-bar';
    };

    // create template that uses custom global filter
    var t = new Luigi.Template('hello %{name | barify | h}');

    // run template, print result to console
    console.log(t.run({
      name: '<Paul>',
    }));

    // prints "hello bar-&lt;Paul&gt;-bar"

You can also create a custom filter and limit it to a particular
template by passing a custom filter hash as the second parameter to the
`Luigi.Template` constructor, like this:

    // create template with custom template-specific filter
    var t = new Luigi.Template('hello %{name | barify | h}', {
      barify: function(s) {
        return 'bar-' + s + '-bar';
      },
    });

    // run template, print result to console
    console.log(t.run({
      name: '<Paul>',
    }));

    // prints "hello bar-&lt;Paul&gt;-bar"

You can pass arguments to your custom filters.  Here's an example:

    // create template with custom template-specific filter named
    // "wrap", which wraps the value in the given filter parameters
    var t = new Luigi.Template('hello %{name | wrap head tail | h}', {
      wrap: function(s, args) {
        if (args.length == 2) {
          return [args[0], s, args[1]].join('-';
        } else if (args.length == 1) {
          return [args[0], s, args[0]].join('-');
        } else {
          return s;
        }
      },
    });

    // run template, print result to console
    console.log(t.run({
      name: '<Paul>',
    }));

    // prints "hello head-&lt;Paul&gt;-tail"

If you have a lot of separate templates, or a few large templates,
then it's a good idea to use a template cache.

A template cache will create templates as they are needed (also known as
"lazy initialization"), so the script loads quickly.  A template cache
also caches instantiated (that is, created) templates for future use, so
that running a template from the cache is fast too.

Here's how you create a template cache:

    // create template cache with a single template
    var cache = Luigi.cache({
      hello: 'hello %{name | uc | h}'
    });

    // run template, print result to console
    console.log(cache.run('hello', {
      name: '<Paul>',
    }));

    // prints "hello &lt;PAUL%gt;"

Template caches use their own set of custom filters by passing a custom
filter hash when creating a template cache:

    // create template cache with a custom filter named "reverse"
    var cache = Luigi.cache({
      hello: 'hello %{name | uc | reverse | h}'
    }, {
      reverse: function(s) {
        var cs = (s || '').split('');
        cs.reverse();
        return cs.join('');
      },
    });

    // run template, print result to console
    console.log(cache.run('hello', {
      name: '<Paul>',
    }));

    // prints "hello %gt;LUAP&lt;"

A template cache is also a convenient way to group all of the templates
in a script together:

    // add global filter named "reverse"
    Luigi.FILTERS.reverse = function(s) {
      var cs = (s || '').split('');
      cs.reverse();
      return cs.join('');
    };

    // create template cache
    var TEMPLATES = Luigi.cache({
      upper:    'hello %{name | uc | h}',
      reverse:  'hello %{name | reverse | h}',
    });

    // run the upper and reverse templates above and populate
    // the elements #upper and #reverse with their respective
    // result
    ['upper', 'reverse'].forEach(function(id) {
      getElementByid(id).innerHTML = TEMPLATES.run(id, {
        name: '<Paul>',
      });
    });

Documentation
-------------
Usage documentation is available in the *Usage* section above, and API
documentation is available online at the following URL:

[https://pablotron.github.io/luigi-template/][api-docs]

See the following sections to generate language-specific API
documentation.

Documentation (Java)
--------------------
The Java implementation of Luigi Template uses the
[maven-javadoc-plugin][] to generate API documentation.

To generate API documentation in `java/target/apidocs/`:

    cd java/
    mvn javadoc:javadoc

To generate API documentation as a `jar` file:

    cd java/
    mvn javadoc:jar

See [this page][maven-javadoc-plugin-usage] for additional options.

Documentation (JavaScript)
--------------------------
You can generate the JavaScript API documentation using [jsdoc][].

Documentation (Ruby)
--------------------
You can generate the Ruby API documentation in the `ruby/docs/`
directory via [RDoc][], like so:

    # generate API documentation in ruby/docs/ directory
    cd ruby/
    rake docs

Tests (Java)
------------
To run the Java test suite, do the following:

    cd java/
    mvn test

Tests (JavaScript)
------------------
This `js/test/` directory contains the test suite for the JavaScript
implementation of [Luigi Template][], written in [Mocha][] and [Chai][].

To run the test suite, load the `js/test/test.html` page in a browser.

Tests (PHP)
------------
You can run the PHP test suite and static analyzer by doing the
following:

    # run php unit tests and static analyzer
    composer test

To run only the unit tests ([PHPUnit][]):

    # run the php unit tests
    composer test-unit

To run only the static analyzer ([Phan][]):

    # run the php static analyzer
    composer test-static

Run the unit tests and generate [JUnit][]-compatible output:

    # run all unit tests and export the results as XML
    composer test-xml

Tests (Ruby)
------------
You can run the [minitest][] test suite via [Rake][], like so:

    # run the test suite
    cd ruby/
    rake test

To generate a [JUnit][]-compatible XML report, install the
[minitest-junit][] gem and then do the following:

    # run the test suite and generate a junit-compatible report.xml
    cd ruby/
    rake test TESTOPTS=--junit

Changes in 0.5.0 (JavaScript)
-----------------------------
Version 0.5.0 of Luigi Template changes the namespace from
`LuigiTemplate` to `Luigi`, which has the following effects:

* old (0.4.x): `new LuigiTemplate(...)`, new (0.5): `new Luigi.Template(...)`
* old (0.4.x): `LuigiTemplate.run(...)`, new: (0.5): `Luigi.run(...)`
* old (0.4.x): `LuigiTemplate.VERSION`, new (0.5): `Luigi.VERSION`
* old (0.4.x): `LuigiTemplate.FILTERS`, new: (0.5): `Luigi.FILTERS`
* old (0.4.x): `new LuigiTemplate.Cache(...)`, new: (0.5): `Luigi.cache(...)` (recommended) or `new Luigi.Cache(...)`

If you have an existing system that you cannot make changes to, you can
include `luigi-compat.js` as a compatibility shim.  Tests for the
compatibility shim are available in `js/test/compat/`.

*Note:* The compatibility shim will disappear in a future release.

Author
------
Paul Duncan ([pabs@pablotron.org][me])<br/>
[https://pablotron.org/][me-web]

License
-------
Copyright 2014-2018 Paul Duncan ([pabs@pablotron.org][me])

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

[composer]: https://getcomposer.org/
[pipe]: https://en.wikipedia.org/wiki/Pipeline_(Unix)
[jsmin]: https://www.crockford.com/javascript/jsmin.html
[Luigi Template]: https://github.com/pablotron/luigi-template
[me]: mailto:pabs@pablotron.org
[me-web]: https://pablotron.org/
[Mocha]: https://mochajs.org/
[Chai]: http://www.chaijs.com/
[jsdoc]: http://usejsdoc.org/
[api-docs]: https://pablotron.github.io/luigi-template/
[maven-javadoc-plugin]: https://maven.apache.org/plugins/maven-javadoc-plugin/
[maven-javadoc-plugin-usage]: https://maven.apache.org/plugins/maven-javadoc-plugin/usage.html
[JUnit]: https://junit.org/
[minitest]: https://github.com/seattlerb/minitest
[minitest-junit]: https://github.com/aespinosa/minitest-junit
[RDoc]: https://github.com/ruby/rdoc
[Rake]: https://github.com/ruby/rake
[PHPUnit]: https://phpunit.de/
[Phan]: https://github.com/phan/phan
[RubyGems]: https://rubygems.org/