This module should be included in every source handler as it provides the default methods for creating nodes.
A source handler is a webgen extension that processes source paths to create nodes and that provides the rendered content of these nodes. The nodes are later written to the output location. This can range from simply copying a path from the source to the output location to generating a whole set of nodes from one input path!
The paths that are handled by a source handler are specified via path patterns (see below). During a webgen run the create_node method for each source paths that matches a specified path pattern is called. And when it is time to write out the node, the content method is called to retrieve the rendered content.
A source handler must not take any parameters on initialization and when this module is not mixed in, the methods create_node and content need to be defined. Also, a source handler does not need to reside under the Webgen::SourceHandler namespace but all shipped ones do.
This base class provides useful default implementations of methods that are used by nearly all source handler classes:
It also provides other utility methods:
The main functions of a source handler class are to create one or more nodes for a source path and to provide the content of these nodes. To achieve this, certain information needs to be set on a created node. If you use the create_node method provided by this base class, you don't need to set them explicitly because this is done by the method:
Has to be set to the class name of the source handler. This is used by the Node class: all unknown method calls are forwarded to the node processor.
Has to be set to the string version of the path that lead to the creation of the node.
Has to be set to the string version of the path that is used to create the path.
Has to be set to true on nodes that are used during a webgen run but do not produce an output file.
Has to be set to the current time if not already set correctly (ie. if not a Time object).
If meta_info['draft'] is set on a path, then no node should be created in create_node and nil has to be returned.
Note: The difference between :src and :creation_path is that a creation path need not have an existing source path representation. For example, fragments created from a page source path have a different :creation_path which includes the fragment part.
Additional information that is used only for processing purposes should be stored in the node_info hash of a node as the meta_info hash is reserved for real node meta information and should not be changed once the node is created.
The method for creating an output path name for a source path is stored in the meta information output_path. If you don't use the provided method output_path, have a look at its implementation to see how to an output path gets created. Individual output path creation methods are stored as methods in the OutputPathHelpers module.
Path patterns define which paths are handled by a specific source handler. These patterns are specified in the sourcehandler.patterns configuration hash as a mapping from the source handler class name to an array of path patterns. The patterns need to have a format that Dir.glob can handle. You can use the configuration helper patterns to set this (is shown in the example below).
Specifying a path pattern does not mean that webgen uses the source handler. One also needs to provide an entry in the configuration value sourcehandler.invoke. This is a hash that maps the invocation rank (a number) to an array of source handler class names. The lower the invocation rank the earlier the specified source handlers are used.
The default invocation ranks are:
Early. Normally there is no need to use this rank.
Standard. This is the rank the normal source handler should use.
Late. This rank should be used by source handlers that operate on/use already created nodes and need to ensure that these nodes are available.
Each source handler can define default meta information that gets automatically set on the source paths that are passed to the create_node method.
The default meta information is specified in the sourcehandler.default_meta_info configuration hash as a mapping from the source handler class name to the meta information hash.
Following is a simple source handler class example which copies paths from the source to the output location modifying the extension:
class SimpleCopy include Webgen::SourceHandler::Base include Webgen::WebsiteAccess def create_node(path) path.ext += '.copied' super(path) end def content(node) website.blackboard.invoke(:source_paths)[node.node_info[:src]].io end end WebsiteAccess.website.config.patterns('SimpleCopy' => ['**/*.jpg', '**/*.png']) WebsiteAccess.website.config.sourcehandler.invoke[5] << 'SimpleCopy'
Return the content of the given node. If the return value is not nil then the node gets written, otherwise it is ignored.
This default content method just returns nil.
# File lib/webgen/sourcehandler/base.rb, line 251 def content(node) nil end
Create a node from path if it does not already exists or re-initalize an already existing node. The found node or the newly created node is returned afterwards. nil is returned if no node can be created (e.g. when path.meta_info['draft'] is set).
The options parameter can be used for providing the optional parameters:
The parent node under which the new node should be created. If this is not specified (the usual case), the parent node is determined by the parent_node method.
The output path that should be used for the node. If this is not specified (the usual case), the output path is determined via the output_path method.
Some additional node information like :src and :processor is set and the meta information is checked for validness. The created/re-initialized node is yielded if a block is given.
# File lib/webgen/sourcehandler/base.rb, line 219 def create_node(path, options = {}) return nil if path.meta_info['draft'] parent = options[:parent] || parent_node(path) output_path = options[:output_path] || self.output_path(parent, path) node = node_exists?(path, output_path) if node && (node.node_info[:src] != path.source_path || node.node_info[:processor] != self.class.name) log(:warn) { "Node already exists: source = #{path.source_path} | path = #{node.path} | alcn = #{node.alcn}"} return node #TODO: think! should nil be returned? elsif !node node = Webgen::Node.new(parent, output_path, path.cn, path.meta_info) elsif node.flagged?(:reinit) node.reinit(output_path, path.meta_info) else return node end if !node['modified_at'].kind_of?(Time) log(:warn) { "Meta information 'modified_at' set to current time in <#{node}> since its value '#{node['modified_at']}' was of type #{node['modified_at'].class}" } unless node['modified_at'].nil? node['modified_at'] = Time.now end node.node_info[:src] = path.source_path node.node_info[:creation_path] = path.path node.node_info[:processor] = self.class.name yield(node) if block_given? node end
Check if the node alcn and output path which would be created by create_node exist. The output_path to check for can individually be set.
# File lib/webgen/sourcehandler/base.rb, line 198 def node_exists?(path, output_path = self.output_path(parent_node(path), path)) Webgen::WebsiteAccess.website.tree[path.alcn] || (!path.meta_info['no_output'] && Webgen::WebsiteAccess.website.tree[output_path, :path]) end
Construct the output name for the given path and parent. First it is checked if a node with the constructed output name already exists. If it exists, the language part is forced to be in the output name and the resulting output name is returned.
# File lib/webgen/sourcehandler/base.rb, line 174 def output_path(parent, path) method = path.meta_info['output_path'] + '_output_path' use_lang_part = if path.meta_info['lang'].nil? # unlocalized files never get a lang in the filename! false else Webgen::WebsiteAccess.website.config['sourcehandler.default_lang_in_output_path'] || Webgen::WebsiteAccess.website.config['website.lang'] != path.meta_info['lang'] end if OutputPathHelpers.public_instance_methods(false).map {|c| c.to_s}.include?(method) name = send(method, parent, path, use_lang_part) name += '/' if path.path =~ /\/$/ && name !~ /\/$/ if (node = node_exists?(path, name)) && node.lang != path.meta_info['lang'] name = send(method, parent, path, (path.meta_info['lang'].nil? ? false : true)) name += '/' if path.path =~ /\/$/ && name !~ /\/$/ end name else raise Webgen::NodeCreationError.new("Unknown method for creating output path: #{path.meta_info['output_path']}", self.class.name, path) end end
Utility method for creating a Webgen::Page object from the path. Also updates path.meta_info with the meta info from the page.
# File lib/webgen/sourcehandler/base.rb, line 257 def page_from_path(path) begin page = Webgen::Page.from_data(path.io.data, path.meta_info) rescue Webgen::Page::FormatError => e raise Webgen::NodeCreationError.new("Error reading source path: #{e.message}", self.class.name, path) end path.meta_info = page.meta_info page end
Return the parent node for the given path.
# File lib/webgen/sourcehandler/base.rb, line 269 def parent_node(path) parent_dir = (path.parent_path == '' ? '' : Webgen::Path.new(path.parent_path).alcn) if !(parent = Webgen::WebsiteAccess.website.tree[parent_dir]) raise Webgen::NodeCreationError.new("The needed parent path <#{parent_dir}> does not exist", self.class.name, path) end parent end
Generated with the Darkfish Rdoc Generator 2.