class Kramdown::Converter::Html
Converts a Kramdown::Document
to HTML.
You can customize the HTML converter by sub-classing it and overriding the convert_NAME
methods. Each such method takes the following parameters:
el
-
The element of type
NAME
to be converted. indent
-
A number representing the current amount of spaces for indent (only used for block-level elements).
The return value of such a method has to be a string containing the element el
formatted as HTML element.
Constants
- FOOTNOTE_BACKLINK_FMT
Attributes
The amount of indentation used when nesting HTML tags.
Public Class Methods
Initialize the HTML converter with the given Kramdown
document doc
.
# File lib/kramdown/converter/html.rb, line 38 def initialize(root, options) super @footnote_counter = @footnote_start = @options[:footnote_nr] @footnotes = [] @footnotes_by_name = {} @footnote_location = nil @toc = [] @toc_code = nil @indent = 2 @stack = [] # stash string representation of symbol to avoid allocations from multiple interpolations. @highlighter_class = " highlighter-#{options[:syntax_highlighter]}" @dispatcher = Hash.new {|h, k| h[k] = :"convert_#{k}" } end
Public Instance Methods
Add the syntax highlighter name to the ‘class’ attribute of the given attribute hash. And overwrites or add a “language-LANG” part using the lang
parameter if lang
is not nil.
# File lib/kramdown/converter/html.rb, line 416 def add_syntax_highlighter_to_class_attr(attr, lang = nil) (attr['class'] = (attr['class'] || '') + @highlighter_class).lstrip! attr['class'].sub!(/\blanguage-\S+|(^)/) { "language-#{lang}#{$1 ? ' ' : ''}" } if lang end
Dispatch the conversion of the element el
to a convert_TYPE
method using the type
of the element.
# File lib/kramdown/converter/html.rb, line 56 def convert(el, indent = -@indent) send(@dispatcher[el.type], el, indent) end
# File lib/kramdown/converter/html.rb, line 282 def convert_a(el, indent) format_as_span_html("a", el.attr, inner(el, indent)) end
# File lib/kramdown/converter/html.rb, line 376 def convert_abbreviation(el, _indent) title = @root.options[:abbrev_defs][el.value] attr = @root.options[:abbrev_attr][el.value].dup attr['title'] = title unless title.empty? format_as_span_html("abbr", attr, el.value) end
# File lib/kramdown/converter/html.rb, line 76 def convert_blank(_el, _indent) "\n" end
# File lib/kramdown/converter/html.rb, line 144 def convert_blockquote(el, indent) format_as_indented_block_html("blockquote", el.attr, inner(el, indent), indent) end
# File lib/kramdown/converter/html.rb, line 278 def convert_br(_el, _indent) "<br />" end
# File lib/kramdown/converter/html.rb, line 114 def convert_codeblock(el, indent) attr = el.attr.dup lang = extract_code_language!(attr) hl_opts = {} highlighted_code = highlight_code(el.value, el.options[:lang] || lang, :block, hl_opts) if highlighted_code add_syntax_highlighter_to_class_attr(attr, lang || hl_opts[:default_lang]) "#{' ' * indent}<div#{html_attributes(attr)}>#{highlighted_code}#{' ' * indent}</div>\n" else result = escape_html(el.value) result.chomp! if el.attr['class'].to_s =~ /\bshow-whitespaces\b/ result.gsub!(/(?:(^[ \t]+)|([ \t]+$)|([ \t]+))/) do |m| suffix = ($1 ? '-l' : ($2 ? '-r' : '')) m.scan(/./).map do |c| case c when "\t" then "<span class=\"ws-tab#{suffix}\">\t</span>" when " " then "<span class=\"ws-space#{suffix}\">⋅</span>" end end.join end end code_attr = {} code_attr['class'] = "language-#{lang}" if lang "#{' ' * indent}<pre#{html_attributes(attr)}>" \ "<code#{html_attributes(code_attr)}>#{result}\n</code></pre>\n" end end
# File lib/kramdown/converter/html.rb, line 290 def convert_codespan(el, _indent) attr = el.attr.dup lang = extract_code_language(attr) hl_opts = {} result = highlight_code(el.value, lang, :span, hl_opts) if result add_syntax_highlighter_to_class_attr(attr, lang || hl_opts[:default_lang]) else result = escape_html(el.value) end format_as_span_html('code', attr, result) end
# File lib/kramdown/converter/html.rb, line 270 def convert_comment(el, indent) if el.options[:category] == :block "#{' ' * indent}<!-- #{el.value} -->\n" else "<!-- #{el.value} -->" end end
# File lib/kramdown/converter/html.rb, line 184 def convert_dl(el, indent) format_as_indented_block_html("dl", el.attr, inner(el, indent), indent) end
# File lib/kramdown/converter/html.rb, line 200 def convert_dt(el, indent) attr = el.attr.dup @stack.last.options[:ial][:refs].each do |ref| if ref =~ /\Aauto_ids(?:-([\w-]+))?/ attr['id'] = "#{$1}#{basic_generate_id(el.options[:raw_text])}".lstrip break end end if !attr['id'] && @stack.last.options[:ial] && @stack.last.options[:ial][:refs] format_as_block_html("dt", attr, inner(el, indent), indent) end
# File lib/kramdown/converter/html.rb, line 330 def convert_em(el, indent) format_as_span_html(el.type, el.attr, inner(el, indent)) end
# File lib/kramdown/converter/html.rb, line 335 def convert_entity(el, _indent) entity_to_str(el.value, el.options[:original]) end
# File lib/kramdown/converter/html.rb, line 304 def convert_footnote(el, _indent) repeat = '' name = @options[:footnote_prefix] + el.options[:name] if (footnote = @footnotes_by_name[name]) number = footnote[2] repeat = ":#{footnote[3] += 1}" else number = @footnote_counter @footnote_counter += 1 @footnotes << [name, el.value, number, 0] @footnotes_by_name[name] = @footnotes.last end formatted_link_text = sprintf(@options[:footnote_link_text], number) "<sup id=\"fnref:#{name}#{repeat}\">" \ "<a href=\"#fn:#{name}\" class=\"footnote\" rel=\"footnote\" role=\"doc-noteref\">" \ "#{formatted_link_text}</a></sup>" end
# File lib/kramdown/converter/html.rb, line 148 def convert_header(el, indent) attr = el.attr.dup if @options[:auto_ids] && !attr['id'] attr['id'] = generate_id(el.options[:raw_text]) end if @options[:header_links] && attr['id'].to_s.length > 0 link = Element.new(:a, nil, nil) link.attr['href'] = "##{attr['id']}" el.children.unshift(link) end @toc << [el.options[:level], attr['id'], el.children] if attr['id'] && in_toc?(el) level = output_header_level(el.options[:level]) format_as_block_html("h#{level}", attr, inner(el, indent), indent) end
# File lib/kramdown/converter/html.rb, line 165 def convert_hr(el, indent) "#{' ' * indent}<hr#{html_attributes(el.attr)} />\n" end
# File lib/kramdown/converter/html.rb, line 211 def convert_html_element(el, indent) res = inner(el, indent) if el.options[:category] == :span "<#{el.value}#{html_attributes(el.attr)}" + \ (res.empty? && HTML_ELEMENTS_WITHOUT_BODY.include?(el.value) ? " />" : ">#{res}</#{el.value}>") else output = +'' if @stack.last.type != :html_element || @stack.last.options[:content_model] != :raw output << ' ' * indent end output << "<#{el.value}#{html_attributes(el.attr)}" if el.options[:is_closed] && el.options[:content_model] == :raw output << " />" elsif !res.empty? && el.options[:content_model] != :block output << ">#{res}</#{el.value}>" elsif !res.empty? output << ">\n#{res.chomp}\n" << ' ' * indent << "</#{el.value}>" elsif HTML_ELEMENTS_WITHOUT_BODY.include?(el.value) output << " />" else output << "></#{el.value}>" end output << "\n" if @stack.last.type != :html_element || @stack.last.options[:content_model] != :raw output end end
# File lib/kramdown/converter/html.rb, line 286 def convert_img(el, _indent) "<img#{html_attributes(el.attr)} />" end
# File lib/kramdown/converter/html.rb, line 188 def convert_li(el, indent) output = ' ' * indent << "<#{el.type}" << html_attributes(el.attr) << ">" res = inner(el, indent) if el.children.empty? || (el.children.first.type == :p && el.children.first.options[:transparent]) output << res << (res.match?(/\n\Z/) ? ' ' * indent : '') else output << "\n" << res << ' ' * indent end output << "</#{el.type}>\n" end
# File lib/kramdown/converter/html.rb, line 362 def convert_math(el, indent) if (result = format_math(el, indent: indent)) result else attr = el.attr.dup attr['class'] = "#{attr['class']} kdmath".lstrip if el.options[:category] == :block format_as_block_html('div', attr, "$$\n#{el.value}\n$$", indent) else format_as_span_html('span', attr, "$#{el.value}$") end end end
# File lib/kramdown/converter/html.rb, line 85 def convert_p(el, indent) if el.options[:transparent] inner(el, indent) elsif el.children.size == 1 && el.children.first.type == :img && el.children.first.options[:ial]&.[](:refs)&.include?('standalone') convert_standalone_image(el, indent) else format_as_block_html("p", el.attr, inner(el, indent), indent) end end
# File lib/kramdown/converter/html.rb, line 322 def convert_raw(el, _indent) if !el.options[:type] || el.options[:type].empty? || el.options[:type].include?('html') el.value + (el.options[:category] == :block ? "\n" : '') else '' end end
# File lib/kramdown/converter/html.rb, line 383 def convert_root(el, indent) result = inner(el, indent) if @footnote_location result.sub!(/#{@footnote_location}/, footnote_content.gsub(/\\/, "\\\\\\\\")) else result << footnote_content end if @toc_code toc_tree = generate_toc_tree(@toc, @toc_code[0], @toc_code[1] || {}) text = toc_tree.children.empty? ? '' : convert(toc_tree, 0) result.sub!(/#{@toc_code.last}/, text.gsub(/\\/, "\\\\\\\\")) end result end
# File lib/kramdown/converter/html.rb, line 358 def convert_smart_quote(el, _indent) entity_to_str(smart_quote_entity(el)) end
Helper method used by convert_p
to convert a paragraph that only contains a single :img element.
# File lib/kramdown/converter/html.rb, line 98 def convert_standalone_image(el, indent) figure_attr = el.attr.dup image_attr = el.children.first.attr.dup if image_attr.key?('class') && !figure_attr.key?('class') figure_attr['class'] = image_attr.delete('class') end if image_attr.key?('id') && !figure_attr.key?('id') figure_attr['id'] = image_attr.delete('id') end body = "#{' ' * (indent + @indent)}<img#{html_attributes(image_attr)} />\n" \ "#{' ' * (indent + @indent)}<figcaption>#{image_attr['alt']}</figcaption>\n" format_as_indented_block_html("figure", figure_attr, body, indent) end
# File lib/kramdown/converter/html.rb, line 248 def convert_table(el, indent) format_as_indented_block_html(el.type, el.attr, inner(el, indent), indent) end
# File lib/kramdown/converter/html.rb, line 258 def convert_td(el, indent) res = inner(el, indent) type = (@stack[-2].type == :thead ? :th : :td) attr = el.attr alignment = @stack[-3].options[:alignment][@stack.last.children.index(el)] if alignment != :default attr = el.attr.dup attr['style'] = (attr.key?('style') ? "#{attr['style']}; " : '') + "text-align: #{alignment}" end format_as_block_html(type, attr, res.empty? ? entity_to_str(ENTITY_NBSP) : res, indent) end
# File lib/kramdown/converter/html.rb, line 80 def convert_text(el, _indent) escaped = escape_html(el.value, :text) @options[:remove_line_breaks_for_cjk] ? fix_cjk_line_break(escaped) : escaped end
# File lib/kramdown/converter/html.rb, line 350 def convert_typographic_sym(el, _indent) if (result = @options[:typographic_symbols][el.value]) escape_html(result, :text) else TYPOGRAPHIC_SYMS[el.value].map {|e| entity_to_str(e) }.join end end
# File lib/kramdown/converter/html.rb, line 172 def convert_ul(el, indent) if !@toc_code && el.options.dig(:ial, :refs)&.include?('toc') @toc_code = [el.type, el.attr, ZERO_TO_ONETWENTYEIGHT.map { rand(36).to_s(36) }.join] @toc_code.last elsif !@footnote_location && el.options.dig(:ial, :refs)&.include?('footnotes') @footnote_location = ZERO_TO_ONETWENTYEIGHT.map { rand(36).to_s(36) }.join else format_as_indented_block_html(el.type, el.attr, inner(el, indent), indent) end end
# File lib/kramdown/converter/html.rb, line 238 def convert_xml_comment(el, indent) if el.options[:category] == :block && (@stack.last.type != :html_element || @stack.last.options[:content_model] != :raw) ' ' * indent << el.value << "\n" else el.value end end
Fixes the elements for use in a TOC entry.
# File lib/kramdown/converter/html.rb, line 460 def fix_for_toc_entry(elements) remove_footnotes(elements) unwrap_links(elements) elements end
Return an HTML ordered list with the footnote content for the used footnotes.
# File lib/kramdown/converter/html.rb, line 495 def footnote_content ol = Element.new(:ol) ol.attr['start'] = @footnote_start if @footnote_start != 1 i = 0 backlink_text = escape_html(@options[:footnote_backlink], :text) while i < @footnotes.length name, data, _, repeat = *@footnotes[i] li = Element.new(:li, nil, 'id' => "fn:#{name}") li.children = Marshal.load(Marshal.dump(data.children)) para = nil if li.children.last.type == :p || @options[:footnote_backlink_inline] parent = li while !parent.children.empty? && ![:p, :header].include?(parent.children.last.type) parent = parent.children.last end para = parent.children.last insert_space = true end unless para li.children << (para = Element.new(:p)) insert_space = false end unless @options[:footnote_backlink].empty? nbsp = entity_to_str(ENTITY_NBSP) value = sprintf(FOOTNOTE_BACKLINK_FMT, (insert_space ? nbsp : ''), name, backlink_text) para.children << Element.new(:raw, value) (1..repeat).each do |index| value = sprintf(FOOTNOTE_BACKLINK_FMT, nbsp, "#{name}:#{index}", "#{backlink_text}<sup>#{index + 1}</sup>") para.children << Element.new(:raw, value) end end ol.children << Element.new(:raw, convert(li, 4)) i += 1 end if ol.children.empty? '' else format_as_indented_block_html('div', {class: "footnotes", role: "doc-endnotes"}, convert(ol, 2), 0) end end
Format the given element as block HTML.
# File lib/kramdown/converter/html.rb, line 404 def format_as_block_html(name, attr, body, indent) "#{' ' * indent}<#{name}#{html_attributes(attr)}>#{body}</#{name}>\n" end
Format the given element as block HTML with a newline after the start tag and indentation before the end tag.
# File lib/kramdown/converter/html.rb, line 410 def format_as_indented_block_html(name, attr, body, indent) "#{' ' * indent}<#{name}#{html_attributes(attr)}>\n#{body}#{' ' * indent}</#{name}>\n" end
Format the given element as span HTML.
# File lib/kramdown/converter/html.rb, line 399 def format_as_span_html(name, attr, body) "<#{name}#{html_attributes(attr)}>#{body}</#{name}>" end
Generate and return an element tree for the table of contents.
# File lib/kramdown/converter/html.rb, line 422 def generate_toc_tree(toc, type, attr) sections = Element.new(type, nil, attr.dup) sections.attr['id'] ||= 'markdown-toc' stack = [] toc.each do |level, id, children| li = Element.new(:li, nil, nil, level: level) li.children << Element.new(:p, nil, nil, transparent: true) a = Element.new(:a, nil) a.attr['href'] = "##{id}" a.attr['id'] = "#{sections.attr['id']}-#{id}" a.children.concat(fix_for_toc_entry(Marshal.load(Marshal.dump(children)))) li.children.last.children << a li.children << Element.new(type) success = false until success if stack.empty? sections.children << li stack << li success = true elsif stack.last.options[:level] < li.options[:level] stack.last.children.last.children << li stack << li success = true else item = stack.pop item.children.pop if item.children.last.children.empty? end end end until stack.empty? item = stack.pop item.children.pop if item.children.last.children.empty? end sections end
Return the converted content of the children of el
as a string. The parameter indent
has to be the amount of indentation used for the element el
.
Pushes el
onto the @stack before converting the child elements and pops it from the stack afterwards.
# File lib/kramdown/converter/html.rb, line 65 def inner(el, indent) result = +'' indent += @indent @stack.push(el) el.children.each do |inner_el| result << send(@dispatcher[inner_el.type], inner_el, indent) end @stack.pop result end
Obfuscate the text
by using HTML entities.
# File lib/kramdown/converter/html.rb, line 483 def obfuscate(text) result = +'' text.each_byte do |b| result << (b > 128 ? b.chr : sprintf("&#%03d;", b)) end result.force_encoding(text.encoding) result end
Remove all footnotes from the given elements.
# File lib/kramdown/converter/html.rb, line 475 def remove_footnotes(elements) elements.delete_if do |c| remove_footnotes(c.children) c.type == :footnote end end
Remove all link elements by unwrapping them.
# File lib/kramdown/converter/html.rb, line 467 def unwrap_links(elements) elements.map! do |c| unwrap_links(c.children) c.type == :a ? c.children : c end.flatten! end