class Webby::Filters::Outline
The Outline filter is used to insert outline numbering into HTML heading tags (h1, h2, h3, etc.) and to generate a table of contents based on the heading tags. The table of contents is inserted into the page at the location of the <toc /> tag. If there is no <toc /> tag, then a table of contents will not be created but outline numbering will still take place.
If a table of contents is desired without outline number being inserted into the heading tags, this can be specified in the attibutes of the <toc /> tag itself.
<toc numbering="off" />
This will generate a table of contents, but not insert outline numbering into the heading tags.
The Outline filter will only work on valid HTML or XHTML pages. Therefore it should be used after any markup langauge filters (textile, markdown, etc.).
The following attributes can be specified in the <toc /> tag itself to control how outline numbering is performed by the filter. The attributes can be used in combination with one another.
numbering¶ ↑
If set to “off”, this will prevent numbers from being inserted into the page. The default is “on”.
<toc numbering="off" />
numbering_start¶ ↑
This is the number to start with when inserting outline numbers into a page. The default is 1.
<toc numbering_start="3" />
toc_style¶ ↑
The style of the Table of Contents list to generated. This will be either “ol” for an ordered list or “ul” for an unordered list. The default is an ordered list.
<toc toc_style="ul" />
toc_range¶ ↑
This limits the numbering to only a subset of the HTML heading tags. The defaul is to number all the heading tags.
<toc toc_range="h1-h3" />
In this example, only the heading tags h1, h2, and h3 will be numbered and included in the table of contents listing.
Example¶ ↑
Generate a table of contents using an unordered list, starting with the number 2, and only numbering heading levels 2, 3, and 4.
<toc numbering_start="2" toc_style="ul" toc_range="h2-h4" />
Public Class Methods
Creates a new outline filter that will operate on the given html string.
# File lib/webby/filters/outline.rb, line 77 def initialize( str ) @str = str @cur_level, @base_level, @cur_depth = nil @level = [0] * 6 @h_rgxp = /^h(\d)$/o @numbering = true @numbering_start = 1 @toc = [] @toc_style = 'ol' @toc_range = 'h1-h6' @list_opening = nil end
Public Instance Methods
Process the original html document passed to the filter when it was created. The document will be scanned for heading tags (h1, h2, etc.) and outline numbering and id attributes will be inserted. A table of contents will also be created and inserted into the page if a <toc /> tag is found.
For example, if there is a heading tag
<h3>Get Fuzzy</h3>
somewhere in a page about comic strips, the tag might be altered as such
<h3 id="h2_2_1"><span class="heading-num">2.2.1</span>Get Fuzzy</h3>
The id attribute is used to generate a linke from the table of contents to this particular heading tag. The original text of the tag is used in the table of contents – “Get Fuzzy” in this example.
# File lib/webby/filters/outline.rb, line 114 def filter doc = Hpricot.XML(@str) # extract directives from the "toc" tag toc_elem = doc.search('toc').first unless toc_elem.nil? @numbering = toc_elem['numbering'] !~ /off/i @numbering_start = Integer(toc_elem['numbering_start']) if toc_elem.has_attribute? 'numbering_start' @toc_style = toc_elem['toc_style'] if toc_elem.has_attribute? 'toc_style' @toc_range = toc_elem['toc_range'] if toc_elem.has_attribute? 'toc_range' end unless %w[ul ol].include? @toc_style raise ArgumentError, "unknown ToC list type '#{@toc_style}'" end m = /h(\d)\s*-\s*h(\d)/i.match @toc_range @toc_range = Integer(m[1])..Integer(m[2]) @list_opening = build_list_opening(toc_elem) headers = @toc_range.map {|x| "h#{x}"} doc.traverse_element(*headers) do |elem| text, id = heading_info(elem) add_to_toc(text, id) if @toc_range.include? current_level end toc_elem.swap(toc) unless toc_elem.nil? doc.to_html end
Private Instance Methods
Add the given text and id reference to the table of contents.
# File lib/webby/filters/outline.rb, line 238 def add_to_toc( text, id ) a = "<a href=\"##{id}\">#{h(text)}</a>" @toc << [depth, a] end
# File lib/webby/filters/outline.rb, line 148 def build_list_opening( elem ) lo = "<#{@toc_style}" unless elem.nil? %w[class style id].each do |atr| next unless elem.has_attribute? atr lo << " %s=\"%s\"" % [atr, elem[atr]] end end if @toc_style == 'ol' and @numbering_start != 1 lo << " start=\"#{@numbering_start}\"" end lo << ">" end
Returns the current heading level number.
# File lib/webby/filters/outline.rb, line 217 def current_level @cur_level end
Set the current heading level. This will set the label and depth as well. An error will be raised if the level is less than the base heading level.
The base heading level will be set to the level if it has not already been set. Therefore, the first heading tag encountered defines the base heading level.
# File lib/webby/filters/outline.rb, line 193 def current_level=( level ) if @base_level.nil? @base_level = @cur_level = level @level[@base_level-1] = @numbering_start-1 end if level < @base_level raise ::Webby::Error, "heading tags are not in order, cannot outline" end if level == @cur_level @level[level-1] += 1 elsif level > @cur_level @cur_level.upto(level-1) {|ii| @level[ii] += 1} else @cur_level.downto(level+1) {|ii| @level[ii-1] = 0} @level[level-1] += 1 end @cur_level = level end
Return the nesting depth of the current heading level with respect to the base heading level. This is a one-based number.
# File lib/webby/filters/outline.rb, line 232 def depth @cur_level - @base_level + 1 end
Returns information for the given heading element. The information is returned as a two element array: [text, id].
This method will also insert outline numbering and an id attribute. The outline numbering can be disabled, but the id attribute must be present for TOC generation.
# File lib/webby/filters/outline.rb, line 169 def heading_info( elem ) m = @h_rgxp.match(elem.name) level = Integer(m[1]) self.current_level = level text = elem.inner_text lbl = label if numbering? elem.children.first.before %Q{<span class="heading-num">#{lbl}</span>} end elem['id'] = "h#{lbl.tr('.','_')}" if elem['id'].nil? return [text, elem['id']] end
Return the label string for the current heading level.
# File lib/webby/filters/outline.rb, line 223 def label rv = @level.dup rv.delete(0) rv.join('.') end
Returns true
if outline numbering should be inserted into the
heading tags. Returns false
otherwise.
# File lib/webby/filters/outline.rb, line 294 def numbering? @numbering end
Returns the table of contents as a collection of nested ordered lists. This is fully formatted HTML.
# File lib/webby/filters/outline.rb, line 246 def toc ary = [] lopen = "<#@toc_style>" lclose = "</#@toc_style>" prev_depth = open = 0 @toc.each do |a| cur = a.first # close out the previous list item if we're at the same level if cur == prev_depth ary << "</li>" # if we are increasing the level, then start a new list elsif cur > prev_depth ary << if ary.empty? then @list_opening else lopen end open += 1 # we are decreasing the level; close out tags but ensure we don't # close out all the tags (leave one open) else (prev_depth - cur).times { ary << "</li>" << lclose open -= 1 break if open <= 0 } if open > 0 ary << "</li>" else ary << lopen open += 1 end end # add the current element ary << "<li>" << a.last prev_depth = cur end # close out the remaingling tags ary << "</li>" << lclose ary.join("\n") end