add inline code docs

lib/jekyll/frontmatter_defaults.rb

@@ -1,10 +1,22 @@
 module Jekyll
   class Configuration
+    # This class handles custom defaults for YAML frontmatter settings.
+    # These are set in _config.yml and apply both to internal use (e.g. layout)
+    # and the data available to liquid.
+    #
+    # It is exposed via the frontmatter_defaults method on the site class.
     class FrontmatterDefaults
+      # Initializes a new instance.
       def initialize(site)
         @site = site
       end
 
+      # Finds a default value for a given setting, filtered by path and type
+      #
+      # path - the path (relative to the source) of the page, post or :draft the default is used in
+      # type - a symbol indicating whether a :page, a :post or a :draft calls this method
+      #
+      # Returns the default value or nil if none was found
       def find(path, type, setting)
         value = nil
         matching_sets(path, type).each do |set|
@@ -13,6 +25,12 @@ module Jekyll
         value
       end
 
+      # Collects a hash with all default values for a page or post
+      #
+      # path - the relative path of the page or post
+      # type - a symbol indicating the type (:post, :page or :draft)
+      #
+      # Returns a hash with all default values (an empty hash if there are none)
       def all(path, type)
         defaults = {}
         matching_sets(path, type).each do |set|
@@ -23,20 +41,41 @@ module Jekyll
 
       private
 
+      # Checks if a given default setting scope matches the given path and type
+      #
+      # scope - the hash indicating the scope, as defined in _config.yml
+      # path - the path to check for
+      # type - the type (:post, :page or :draft) to check for
+      #
+      # Returns true if the scope applies to the given path and type
       def applies?(scope, path, type)
         (scope['path'].empty? || path.starts_with?(scope['path'])) && (!scope.has_key?('type') || scope['type'] == type.to_s)
       end
 
+      # Checks if a given set of default values is valid
+      #
+      # set - the default value hash, as defined in _config.yml
+      #
+      # Returns true if the set is valid and can be used in this class
       def valid?(set)
         set.is_a?(Hash) && set['scope'].is_a?(Hash) && set['scope']['path'].is_a?(String) && set['values'].is_a?(Hash)
       end
 
+      # Collects a list of sets that match the given path and type
+      #
+      # Returns an array of hashes
       def matching_sets(path, type)
         valid_sets.select do |set|
           applies?(set['scope'], path, type)
         end
       end
 
+      # Returns a list of valid sets
+      #
+      # This is not cached to allow plugins to modify the configuration
+      # and have their changes take effect
+      #
+      # Returns an array of hashes
       def valid_sets
         sets = @site.config['defaults']
         return [] unless sets.is_a?(Array)