module Webgen::ContentProcessor::Blocks

Replaces special XML tags with the rendered content of a node block.

The module provides a ::call method so that it can be used by the content processor extension. However, it also provides the ::render_block method that contains the actual logic for rendering a block of a node given a render context.

Public Class Methods

call(context) click to toggle source

Replace the webgen:block xml tags with the rendered content of the specified node.

# File lib/webgen/content_processor/blocks.rb, line 19
def self.call(context)
  context.content.gsub!(BLOCK_RE) do |match|
    attr = {}
    match_object = $~
    attr[:line_nr_proc] = lambda { match_object.pre_match.scan("\n").size + 1 }
    match.scan(BLOCK_ATTR_RE) {|name, sep, content| attr[name.to_sym] = content}
    render_block(context, attr)
  end
  context
end

render_block(context, options) click to toggle source

Render a block of a page node and return the result.

The Webgen::Context object context is used as the render context and the options hash needs to hold all relevant information, that is:

:name (mandatory): The name of the block that should be used.
:chain: The node chain used for rendering. If this is not specified, the node chain from the context is used. It needs to be a String in the format '(A)LCN;(A)LCN;…' or an array of nodes.
:node: Defines which node in the node chain should be used. Valid values are next (= default value; the next node in the node chain), first (the first node in the node chain with a block called name) or current (the currently rendered node, ignores the chain option).
:notfound: If this property is set to ignore, a missing block will not raise an error. It is unset by default, so missing blocks will raise errors.

# File lib/webgen/content_processor/blocks.rb, line 52
def self.render_block(context, options)
  if options[:chain].nil?
    used_chain = (context[:chain].length > 1 ? context[:chain][1..-1] : context[:chain].dup)
  elsif options[:chain].kind_of?(Array)
    used_chain = options[:chain]
  else
    paths = options[:chain].split(';')
    used_chain = paths.collect do |path|
      context.ref_node.resolve(path.strip, context.dest_node.lang, true)
    end.compact
    return '' if used_chain.length != paths.length
  end
  dest_node = context.dest_node

  if options[:node] == 'first'
    used_chain.shift while used_chain.length > 0 && !used_chain.first.blocks.has_key?(options[:name])
  elsif options[:node] == 'current'
    used_chain = context[:chain].dup
  end
  block_node = used_chain.first

  if !block_node || !block_node.blocks.has_key?(options[:name])
    if options[:notfound] == 'ignore'
      return ''
    elsif block_node
      raise Webgen::RenderError.new("No block named '#{options[:name]}' found in <#{block_node}>",
                                    'content_processor.blocks', context.dest_node,
                                    context.ref_node, (options[:line_nr_proc].call if options[:line_nr_proc]))
    else
      raise Webgen::RenderError.new("No node in the render chain has a block named '#{options[:name]}'",
                                    'content_processor.blocks', context.dest_node,
                                    context.ref_node, (options[:line_nr_proc].call if options[:line_nr_proc]))
    end
  end

  tmp_context = block_node.render_block(options[:name], context.clone(:chain => used_chain, :dest_node => dest_node))
  tmp_context.content
end