Create parameterised include for shuffle panel

Also added some liquid extensions

docs/_includes/custom/shuffle_panel.html

@@ -0,0 +1,43 @@
+<!-- Argument summary: -->
+
+<!-- tag: tag determining the pages included in the panel -->
+<!-- title: Display title of the panel -->
+<!-- description: Description of the panel -->
+<!-- image (optional) : Name of the image to use, as a css class, eg "fa-list" -->
+<!-- titlemaker (optional) : name of a variable that's evaluated to determine the displayed title of the page. Default is page.title -->
+
+
+{% capture titlemaker %} {{ include.titlemaker | or_else: "page.title" }} {% endcapture %}
+
+
+<div class="col-xs-6 col-sm-4 col-md-4" data-groups='["{{ include.tag }}"]'>
+    <div class="panel panel-default">
+
+
+        {% if include.image != "" and include.image != nil %}
+            <div class="panel-heading text-center">
+                     <span class="fa-stack fa-5x">
+                       <i class="fa fa-circle fa-stack-2x text-secondary"></i>
+                       <i class="fa {{ include.image }} fa-stack-1x fa-inverse"></i>
+                     </span>
+            </div>
+        {% endif %}
+
+        <div class="panel-heading text-center">{{ include.title }}</div>
+        <div class="panel-body">
+
+            <p class="landing-page cat-description">
+                {{ include.description }}
+            </p>
+            <ul>
+                {% for page in site.pages %}
+                {% for tag in page.tags %}
+                {% if tag == include.tag %}
+                <li><a href="{{page.url | remove: '/'}}">{% eval titlemaker %}</a></li>
+                {% endif %}
+                {% endfor %}
+                {% endfor %}
+            </ul>
+        </div>
+    </div>
+</div>

docs/_includes/custom/shuffle_panel_filler.html

@@ -0,0 +1,5 @@
+
+<div class="col-xs-6 col-sm-4 col-md-4 shuffle-panel-filler">
+
+
+</div>

docs/_plugins/custom_filters.rb

@@ -0,0 +1,13 @@
+module CustomFilters
+  # returns the input if it's a non-blank string, otherwise return default value
+  def or_else(input, default)
+    if input
+      input.strip != "" ? input : default
+    else
+      default
+    end
+  end
+
+end
+
+Liquid::Template.register_filter(CustomFilters)

docs/_plugins/eval_tag.rb

@@ -0,0 +1,33 @@
+
+# This tag takes a variable name as an input, and evaluates its value twice
+# (follows one indirection)
+# E.g. if the symbol table is E = {"foo" => "bar", "bar" => "baz"},
+# then {% eval foo %} ~> E[E["foo"]] ~> E["bar"] ~> "baz"
+
+class EvalTag < Liquid::Tag
+
+  def initialize(tag_name, name_expression, tokens)
+    super
+    @name_expression = name_expression.strip
+  end
+
+
+  # Lookup allows access to the page/post variables through the tag context
+  def lookup(context, name)
+    lookup = context
+    name.split(".").each {|value|
+      lookup = lookup[value]
+    }
+    lookup
+  end
+
+  def render(context)
+    # puts "evaluating: #{@name_expression}"
+    # puts "1: #{lookup(context, @name_expression)}"
+    # puts "2: #{lookup(context, lookup(context, @name_expression).strip)}"
+    lookup(context, lookup(context, @name_expression).strip)
+  end
+end
+
+
+Liquid::Template.register_tag('eval', EvalTag)

docs/css/pmd-customstyles.css

@@ -9,5 +9,5 @@
 }
 
 .landing-page.cat-description {
-    margin-bottom: .5cm;
+    margin-top: .4cm;
 }

docs/index.md

@@ -89,35 +89,22 @@ First time user? Then you may be interested in our [quickstart page](TODO).
 # More details
 
 
-<div id="grid" class="row">
+{% include custom/shuffle_panel.html
-           <div class="col-xs-6 col-sm-4 col-md-4" data-groups='["rule_references"]'>
+   tag="getting_started"
-             <div class="panel panel-default">
+   title="Getting started" %}
-               <div class="panel-heading text-center">
+
-                 <span class="fa-stack fa-5x">
+
-                   <i class="fa fa-circle fa-stack-2x text-primary"></i>
+{% include custom/shuffle_panel.html
-                   <i class="fa fa-list fa-stack-1x fa-inverse"></i>
+   tag="rule_references"
-                 </span>
+   title="Rule references"
-               </div>
+   description="Pick your language to find out about the rule it supports:"
-               <div class="panel-body">
+   image="fa-database"
-                 <div class="text-center landing-page cat-title">
+   titlemaker="page.language_name" %}
-                   <h4>Rule references</h4>
+
-                 </div>
+{% include custom/shuffle_panel_filler.html %}
-                 <p class="landing-page cat-description">
+
-                   Pick your language to find out about the rule it supports.
+
-                 </p>
+
-                 <ul>
-                   {% for page in site.pages %}
-                   {% for tag in page.tags %}
-                   {% if tag == "rule_references" %}
-                     <li><a href="{{page.url | remove: '/'}}">{{page.language_name}}</a></li>
-                   {% endif %}
-                   {% endfor %}
-                   {% endfor %}
-                 </ul>
-               </div>
-             </div>
-           </div>
-</div>
 
 <!-- {% include image.html file="pmd-logo-big.png" alt="PMD Logo" %} -->