# -*- coding: utf-8 -*-
#
#--
# Copyright (C) 2009-2010 Thomas Leitner <t_leitner@gmx.at>
#
# This file is part of kramdown.
#
# kramdown is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#++
#
require 'rexml/parsers/baseparser'
require 'strscan'
module Kramdown
module Parser
# Used for parsing a HTML document.
class Html < Base
# Contains all constants that are used when parsing.
module Constants
#:stopdoc:
# The following regexps are based on the ones used by REXML, with some slight modifications.
HTML_DOCTYPE_RE = /<!DOCTYPE.*?>/m
HTML_COMMENT_RE = /<!--(.*?)-->/m
HTML_INSTRUCTION_RE = /<\?(.*?)\?>/m
HTML_ATTRIBUTE_RE = /\s*(#{REXML::Parsers::BaseParser::UNAME_STR})\s*=\s*(["'])(.*?)\2/m
HTML_TAG_RE = /<((?>#{REXML::Parsers::BaseParser::UNAME_STR}))\s*((?>\s+#{REXML::Parsers::BaseParser::UNAME_STR}\s*=\s*(["']).*?\3)*)\s*(\/)?>/m
HTML_TAG_CLOSE_RE = /<\/(#{REXML::Parsers::BaseParser::NAME_STR})\s*>/m
HTML_ENTITY_RE = /&([\w:][\-\w\d\.:]*);|&#(\d+);|&\#x([0-9a-fA-F]+);/
HTML_PARSE_AS_BLOCK = %w{applet button blockquote colgroup dd div dl fieldset form iframe li
map noscript object ol table tbody thead tfoot tr td ul}
HTML_PARSE_AS_SPAN = %w{a abbr acronym address b bdo big cite caption del dfn dt em
h1 h2 h3 h4 h5 h6 i ins kbd label legend optgroup p q rb rbc
rp rt rtc ruby samp select small span strong sub sup th tt var}
HTML_PARSE_AS_RAW = %w{script math option textarea pre code}
HTML_PARSE_AS = Hash.new {|h,k| h[k] = :raw}
HTML_PARSE_AS_BLOCK.each {|i| HTML_PARSE_AS[i] = :block}
HTML_PARSE_AS_SPAN.each {|i| HTML_PARSE_AS[i] = :span}
HTML_PARSE_AS_RAW.each {|i| HTML_PARSE_AS[i] = :raw}
# Some HTML elements like script belong to both categories (i.e. are valid in block and
# span HTML) and don't appear therefore!
HTML_SPAN_ELEMENTS = %w{a abbr acronym b big bdo br button cite code del dfn em i img input
ins kbd label option q rb rbc rp rt rtc ruby samp select small span
strong sub sup textarea tt var}
HTML_BLOCK_ELEMENTS = %w{address article aside applet body button blockquote caption col colgroup dd div dl dt fieldset
figcaption footer form h1 h2 h3 h4 h5 h6 header hgroup hr html head iframe legend listing menu
li map nav ol optgroup p pre section summary table tbody td th thead tfoot tr ul}
HTML_ELEMENTS_WITHOUT_BODY = %w{area base br col command embed hr img input keygen link meta param source track wbr}
end
# Contains the parsing methods. This module can be mixed into any parser to get HTML parsing
# functionality. The only thing that must be provided by the class are instance variable
# <tt>@stack</tt> for storing needed state and <tt>@src</tt> (instance of StringScanner) for
# the actual parsing.
module Parser
include Constants
# Process the HTML start tag that has already be scanned/checked. Does the common processing
# steps and then yields to the caller for further processing.
def handle_html_start_tag
name = @src[1]
closed = !@src[4].nil?
attrs = {}
@src[2].scan(HTML_ATTRIBUTE_RE).each {|attr,sep,val| attrs[attr] = val}
el = Element.new(:html_element, name, :attr => attrs, :category => :block)
@tree.children << el
if !closed && HTML_ELEMENTS_WITHOUT_BODY.include?(el.value)
warning("The HTML tag '#{el.value}' cannot have any content - auto-closing it")
closed = true
end
if name == 'script'
handle_html_script_tag
yield(el, true)
else
yield(el, closed)
end
end
def handle_html_script_tag
curpos = @src.pos
if result = @src.scan_until(/(?=<\/script\s*>)/m)
add_text(extract_string(curpos...@src.pos, @src), @tree.children.last, :raw)
@src.scan(HTML_TAG_CLOSE_RE)
else
add_text(@src.scan(/.*/m), @tree.children.last, :raw)
warning("Found no end tag for 'script' - auto-closing it")
end
end
HTML_RAW_START = /(?=<(#{REXML::Parsers::BaseParser::UNAME_STR}|\/|!--|\?))/
# Parse raw HTML from the current source position, storing the found elements in +el+.
# Parsing continues until one of the following criteria are fulfilled:
#
# - The end of the document is reached.
# - The matching end tag for the element +el+ is found (only used if +el+ is an HTML
# element).
#
# When an HTML start tag is found, processing is deferred to #handle_html_start_tag,
# providing the block given to this method.
def parse_raw_html(el, &block)
@stack.push(@tree)
@tree = el
done = false
while !@src.eos? && !done
if result = @src.scan_until(HTML_RAW_START)
add_text(result, @tree, :text)
if result = @src.scan(HTML_COMMENT_RE)
@tree.children << Element.new(:xml_comment, result, :category => :block, :parent_is_raw => true)
elsif result = @src.scan(HTML_INSTRUCTION_RE)
@tree.children << Element.new(:xml_pi, result, :category => :block, :parent_is_raw => true)
elsif @src.scan(HTML_TAG_RE)
handle_html_start_tag(&block)
elsif @src.scan(HTML_TAG_CLOSE_RE)
if @tree.value == @src[1]
done = true
else
warning("Found invalidly used HTML closing tag for '#{@src[1]}' - ignoring it")
end
else
add_text(@src.scan(/./), @tree, :text)
end
else
result = @src.scan(/.*/m)
add_text(result, @tree, :text)
warning("Found no end tag for '#{@tree.value}' - auto-closing it") if @tree.type == :html_element
done = true
end
end
@tree = @stack.pop
end
end
# Converts HTML elements to native elements if possible.
class ElementConverter
include Constants
REMOVE_TEXT_CHILDREN = %w{html head hgroup ol ul dl table colgroup tbody thead tfoot tr select optgroup}
REMOVE_WHITESPACE_CHILDREN = %w{body section nav article aside header footer address
div li dd blockquote figure figcaption td th fieldset form}
STRIP_WHITESPACE = %w{address article aside blockquote body caption dd div dl dt fieldset figcaption form footer
header h1 h2 h3 h4 h5 h6 legend li nav p section td th}
SIMPLE_ELEMENTS = %w{em strong blockquote hr br a img p thead tbody tfoot tr td th ul ol dl li dl dt dd}
# Convert the element +el+ and its children.
def process(el, convert_simple = true, parent = nil)
case el.type
when :xml_comment, :xml_pi, :html_doctype
ptype = if parent.nil?
'div'
else
case parent.type
when :html_element then parent.value
when :code_span then 'code'
when :code_block then 'pre'
when :header then 'h1'
else parent.type.to_s
end
end
el.options = {:category => HTML_PARSE_AS_SPAN.include?(ptype) ? :span : :block}
return
when :html_element
else return
end
type = el.value
remove_text_children(el) if REMOVE_TEXT_CHILDREN.include?(type)
mname = "convert_#{el.value}"
if self.class.method_defined?(mname)
send(mname, el)
elsif convert_simple && SIMPLE_ELEMENTS.include?(type)
set_basics(el, type.intern, HTML_SPAN_ELEMENTS.include?(type) ? :span : :block)
process_children(el, convert_simple)
else
process_html_element(el, convert_simple)
end
strip_whitespace(el) if STRIP_WHITESPACE.include?(type)
remove_whitespace_children(el) if REMOVE_WHITESPACE_CHILDREN.include?(type)
end
def process_children(el, convert_simple = true)
el.children.map! do |c|
if c.type == :text
process_text(c.value)
else
process(c, convert_simple, el)
c
end
end.flatten!
end
# Process the HTML text +raw+: compress whitespace (if +preserve+ is +false+) and convert
# entities in entity elements.
def process_text(raw, preserve = false)
raw.gsub!(/\s+/, ' ') unless preserve
src = StringScanner.new(raw)
result = []
while !src.eos?
if tmp = src.scan_until(/(?=#{HTML_ENTITY_RE})/)
result << Element.new(:text, tmp)
src.scan(HTML_ENTITY_RE)
val = src[1] || (src[2] && src[2].to_i) || src[3].hex
result << if %w{lsquo rsquo ldquo rdquo}.include?(val)
Element.new(:smart_quote, val.intern)
elsif %w{mdash ndash hellip laquo raquo}.include?(val)
Element.new(:typographic_sym, val.intern)
else
Element.new(:entity, val)
end
else
result << Element.new(:text, src.scan(/.*/m))
end
end
result
end
def process_html_element(el, convert_simple = true)
el.options = {:category => HTML_SPAN_ELEMENTS.include?(el.value) ? :span : :block,
:parse_type => HTML_PARSE_AS[el.value],
:attr => el.options[:attr]
}
process_children(el, convert_simple)
end
def remove_text_children(el)
el.children.delete_if {|c| c.type == :text}
end
def strip_whitespace(el)
return if el.children.empty?
if el.children.first.type == :text
el.children.first.value.lstrip!
end
if el.children.last.type == :text
el.children.last.value.rstrip!
end
end
def remove_whitespace_children(el)
i = -1
el.children.delete_if do |c|
i += 1
c.type == :text && c.value.strip.empty? &&
(i == 0 || i == el.children.length - 1 || (el.children[i-1].options[:category] == :block &&
el.children[i+1].options[:category] == :block))
end
end
def set_basics(el, type, category, opts = {})
el.type = type
el.options = {:category => category, :attr => el.options[:attr]}.merge(opts)
el.value = nil
end
def extract_text(el, raw)
raw << el.value.to_s if el.type == :text
el.children.each {|c| extract_text(c, raw)}
end
def convert_h1(el)
set_basics(el, :header, :block, :level => el.value[1..1].to_i)
extract_text(el, el.options[:raw_text] = '')
process_children(el)
end
%w{h2 h3 h4 h5 h6}.each {|i| alias_method("convert_#{i}".intern, :convert_h1)}
def convert_code(el)
if el.value == 'code'
set_basics(el, :codespan, :span)
else
set_basics(el, :codeblock, :block)
end
raw = ''
extract_text(el, raw)
result = process_text(raw, true)
if result.length > 1 || result.first.type != :text
el.children = result
else
el.value = result.first.value
end
end
alias :convert_pre :convert_code
def convert_table(el)
if !is_simple_table?(el)
process_html_element(el, false)
return
end
process_children(el)
set_basics(el, :table, :block)
el.options[:alignment] = []
helper = lambda do |c|
if c.type == :tr && el.options[:alignment].empty?
el.options[:alignment] = [:default] * c.children.length
break
else
c.children.each {|cc| helper.call(cc)}
end
end
helper.call(el)
true
end
def is_simple_table?(el)
only_phrasing_content = lambda do |c|
c.children.all? do |cc|
(cc.type == :text || !HTML_BLOCK_ELEMENTS.include?(cc.value)) && only_phrasing_content.call(cc)
end
end
helper = Proc.new do |c|
if c.value == 'th' || c.value == 'td'
return false if !only_phrasing_content.call(c)
else
c.children.each {|cc| helper.call(cc)}
end
end
helper.call(el)
true
end
end
include Parser
# Parse +source+ as HTML document and return the created +tree+.
def parse(source)
@stack = []
@tree = Element.new(:root)
@src = StringScanner.new(adapt_source(source))
while true
if result = @src.scan(/\s*#{HTML_INSTRUCTION_RE}/)
@tree.children << Element.new(:xml_pi, result.strip, :category => :block)
elsif result = @src.scan(/\s*#{HTML_DOCTYPE_RE}/)
@tree.children << Element.new(:html_doctype, result.strip, :category => :block)
elsif result = @src.scan(/\s*#{HTML_COMMENT_RE}/)
@tree.children << Element.new(:xml_comment, result.strip, :category => :block)
else
break
end
end
tag_handler = lambda do |c, closed|
parse_raw_html(c, &tag_handler) if !closed
end
parse_raw_html(@tree, &tag_handler)
ec = ElementConverter.new
@tree.children.each {|c| ec.process(c)}
ec.remove_whitespace_children(@tree)
@tree
end
end
end
end