change list filter behavior and make associated plugin changes

_includes/button.html

@@ -1,5 +1,4 @@
-{% assign button = include %}
-{% assign button = button | hash_default: site.data.types[include.type] %}
+{% assign button = include | hash_default: site.data.types[include.type] %}
 
 {% if button.link or button.icon or button.text %}
   <div class="button-wrapper">

_includes/list.html

@@ -2,7 +2,7 @@
 {% assign data = site.data[include.data]
   | default: site[include.data]
   | default: emptyarray
-  | data_filter: include.filters
+  | data_filter: include.filter
 %}
 
 {% assign years = data

_plugins/hash.rb

@@ -4,7 +4,7 @@ module Jekyll
   module HashFilters
     # merge main hash with another hash of defaults
     def hash_default(hash, defaults)
-      if not hash.is_a?(Hash) or not defaults.is_a?(Hash)
+      if not defaults.is_a?(Hash)
         return hash
       end
       defaults.each do |key, value|

_plugins/misc.rb

@@ -19,22 +19,52 @@ def object_items(object)
     end
 
     # filter a list of hashes by comma-sep'd field:value pairs
-    def data_filter(data, filters)
-      if not data.is_a?(Array) or not filters.is_a?(String)
+    def empty_binding
+      binding
+    end
+
+    # make arbitrary string into valid ruby variable name
+    def safe_var_name(name)
+      return name.to_s.gsub /[^a-z]+/, "_"
+    end
+
+    # jekyll ruby plugin
+    def data_filter(data, filter)
+      if not filter.is_a?(String)
         return data
       end
-      data = data.clone
-      for filter in array_filter(filters.split(","))
-        key, value = array_filter(filter.split(":"))
-        # find unspecified fields
-        if value == nil
-          data.select!{|d| d[key] == nil}
-        # find fields that match regex
-        elsif value.is_a?(String)
-          data.select!{|d| d[key].to_s =~ /#{value}/m}
+
+      # filter data
+      return data.clone.select{
+        |item|
+        # start with empty context of local variables
+        b = empty_binding
+        # add item as local variable
+        b.local_variable_set("item", item)
+        # if jekyll doc collection, get hash of doc data
+        if item.is_a? Jekyll::Document
+          item = item.data
         end
-      end
-      return data
+        # also set each item field as local variable when evaluating filter
+        item.each do |var, val|
+          b.local_variable_set(safe_var_name(var), val)
+        end
+        # whether to keep item
+        keep = true
+        while true
+          begin
+            # evaluate filter code, coerce to true/false
+            keep = !!eval(filter, b)
+            # if no error, done
+            break
+          rescue NameError => e
+            # if var in filter doesn't exist, define it and re-evaluate
+            b.local_variable_set(safe_var_name(e.name), nil)
+          end
+        end
+        # keep/discard item
+        keep
+      }
     end
 
     # from css text, find font family definitions and construct google font url

projects/index.md

@@ -18,10 +18,10 @@ Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliqu
 
 ## Featured
 
-{% include list.html component="card" data="projects" filters="group: featured" %}
+{% include list.html component="card" data="projects" filter="group == 'featured'" %}
 
 {% include section.html %}
 
 ## More
 
-{% include list.html component="card" data="projects" filters="group: " style="small" %}
+{% include list.html component="card" data="projects" filter="!group" style="small" %}

team/index.md

@@ -13,8 +13,8 @@ nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
 
 {% include section.html %}
 
-{% include list.html data="members" component="portrait" filters="role: pi" %}
-{% include list.html data="members" component="portrait" filters="role: ^(?!pi$)" %}
+{% include list.html data="members" component="portrait" filter="role == 'pi'" %}
+{% include list.html data="members" component="portrait" filter="role != 'pi'" %}
 
 {% include section.html background="images/background.jpg" dark=true %}