# class Kramdown::Converter::Latex

Converts an element tree to LaTeX.

This converter uses ideas from other Markdown-to-LaTeX converters like Pandoc and Maruku.

You can customize this 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.

`opts`

  A hash containing processing options that are passed down from parent elements. The key :parent is always set and contains the parent element as value.

The return value of such a method has to be a string containing the element `el` formatted correctly as LaTeX markup.

### Public Class Methods

new(root, options) click to toggle source

Initialize the LaTeX converter with the `root` element and the conversion `options`.

Calls superclass method `Kramdown::Converter::Base::new`

       # File lib/kramdown/converter/latex.rb
    33 def initialize(root, options)
    34   super
    35   @data[:packages] = Set.new
    36 end

### Public Instance Methods

attribute_list(el) click to toggle source

Return a LaTeX comment containing all attributes as 'key=“value”' pairs.

        # File lib/kramdown/converter/latex.rb
    592 def attribute_list(el)
    593   attrs = el.attr.map {|k,v| v.nil? ? '' : " #{k}=\"#{v.to_s}\""}.compact.sort.join('')
    594   attrs = "   % #{attrs}" if !attrs.empty?
    595   attrs
    596 end

convert(el, opts = {}) click to toggle source

Dispatch the conversion of the element `el` to a `convert_TYPE` method using the `type` of the element.

       # File lib/kramdown/converter/latex.rb
    40 def convert(el, opts = {})
    41   send("convert_#{el.type}", el, opts)
    42 end

convert_a(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    209 def convert_a(el, opts)
    210   url = el.attr['href']
    211   if url.start_with?('#')
    212     "\\hyperlink{#{url[1..-1].gsub('%', "\\%")}}{#{inner(el, opts)}}"
    213   else
    214     "\\href{#{url.gsub('%', "\\%")}}{#{inner(el, opts)}}"
    215   end
    216 end

convert_abbreviation(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    562 def convert_abbreviation(el, opts)
    563   @data[:packages] += %w[acronym]
    564   "\\ac{#{normalize_abbreviation_key(el.value)}}"
    565 end

convert_blank(el, opts) click to toggle source

       # File lib/kramdown/converter/latex.rb
    60 def convert_blank(el, opts)
    61   opts[:result] =~ /\n\n\Z|\A\Z/ ? "" : "\n"
    62 end

convert_blockquote(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    105 def convert_blockquote(el, opts)
    106   latex_environment(el.children.size > 1 ? 'quotation' : 'quote', el, inner(el, opts))
    107 end

convert_br(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    203 def convert_br(el, opts)
    204   res = "\\newline"
    205   res << "\n" if (c = opts[:parent].children[opts[:index]+1]) && (c.type != :text || c.value !~ /^\s*\n/)
    206   res
    207 end

convert_codeblock(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
     83 def convert_codeblock(el, opts)
     84   show_whitespace = el.attr['class'].to_s =~ /\bshow-whitespaces\b/
     85   lang = extract_code_language(el.attr)
     86
     87   if @options[:syntax_highlighter] == :minted &&
     88       (highlighted_code = highlight_code(el.value, lang, :block))
     89     @data[:packages] << 'minted'
     90     "#{latex_link_target(el)}#{highlighted_code}\n"
     91   elsif show_whitespace || lang
     92     options = []
     93     options << "showspaces=%s,showtabs=%s" % (show_whitespace ? ['true', 'true'] : ['false', 'false'])
     94     options << "language=#{lang}" if lang
     95     options << "basicstyle=\\ttfamily\\footnotesize,columns=fixed,frame=tlbr"
     96     id = el.attr['id']
     97     options << "label=#{id}" if id
     98     attrs = attribute_list(el)
     99     "#{latex_link_target(el)}\\begin{lstlisting}[#{options.join(',')}]\n#{el.value}\n\\end{lstlisting}#{attrs}\n"
    100   else
    101     "#{latex_link_target(el)}\\begin{verbatim}#{el.value}\\end{verbatim}\n"
    102   end
    103 end

convert_codespan(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    232 def convert_codespan(el, opts)
    233   lang = extract_code_language(el.attr)
    234   if @options[:syntax_highlighter] == :minted &&
    235       (highlighted_code = highlight_code(el.value, lang, :span))
    236     @data[:packages] << 'minted'
    237     "#{latex_link_target(el)}#{highlighted_code}"
    238   else
    239     "\\texttt{#{latex_link_target(el)}#{escape(el.value)}}"
    240   end
    241 end

convert_comment(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    199 def convert_comment(el, opts)
    200   el.value.split(/\n/).map {|l| "% #{l}"}.join("\n") << "\n"
    201 end

convert_dd(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    146 def convert_dd(el, opts)
    147   "#{latex_link_target(el)}#{inner(el, opts)}\n\n"
    148 end

convert_dl(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    134 def convert_dl(el, opts)
    135   latex_environment('description', el, inner(el, opts))
    136 end

convert_dt(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    142 def convert_dt(el, opts)
    143   "\\item[#{inner(el, opts)}] "
    144 end

convert_em(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    256 def convert_em(el, opts)
    257   "\\emph{#{latex_link_target(el)}#{inner(el, opts)}}"
    258 end

convert_entity(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    526 def convert_entity(el, opts)
    527   entity_to_latex(el.value)
    528 end

convert_footnote(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    243 def convert_footnote(el, opts)
    244   @data[:packages] << 'fancyvrb'
    245   "\\footnote{#{inner(el.value, opts).rstrip}}"
    246 end

convert_header(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    109 def convert_header(el, opts)
    110   type = @options[:latex_headers][output_header_level(el.options[:level]) - 1]
    111   if ((id = el.attr['id']) ||
    112       (@options[:auto_ids] && (id = generate_id(el.options[:raw_text])))) && in_toc?(el)
    113     "\\#{type}{#{inner(el, opts)}}\\hypertarget{#{id}}{}\\label{#{id}}\n\n"
    114   else
    115     "\\#{type}*{#{inner(el, opts)}}\n\n"
    116   end
    117 end

convert_hr(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    119 def convert_hr(el, opts)
    120   attrs = attribute_list(el)
    121   "#{latex_link_target(el)}\\begin{center}#{attrs}\n\\rule{3in}{0.4pt}\n\\end{center}#{attrs}\n"
    122 end

convert_html_element(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    150 def convert_html_element(el, opts)
    151   if el.value == 'i' || el.value == 'em'
    152     "\\emph{#{inner(el, opts)}}"
    153   elsif el.value == 'b' || el.value == 'strong'
    154     "\\textbf{#{inner(el, opts)}}"
    155   else
    156     warning("Can't convert HTML element")
    157     ''
    158   end
    159 end

convert_img(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    218 def convert_img(el, opts)
    219   line = el.options[:location]
    220   if el.attr['src'] =~ /^(https?|ftps?):\/\//
    221     warning("Cannot include non-local image#{line ? " (line #{line})" : ''}")
    222     ''
    223   elsif !el.attr['src'].empty?
    224     @data[:packages] << 'graphicx'
    225     "#{latex_link_target(el)}\\includegraphics{#{el.attr['src']}}"
    226   else
    227     warning("Cannot include image with empty path#{line ? " (line #{line})" : ''}")
    228     ''
    229   end
    230 end

convert_li(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    138 def convert_li(el, opts)
    139   "\\item{} #{latex_link_target(el, true)}#{inner(el, opts).sub(/\n+\Z/, '')}\n"
    140 end

convert_math(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    549 def convert_math(el, opts)
    550   @data[:packages] += %w[amssymb amsmath amsthm amsfonts]
    551   if el.options[:category] == :block
    552     if el.value =~ /\A\s*\\begin\{/
    553       el.value
    554     else
    555       latex_environment('displaymath', el, el.value)
    556     end
    557   else
    558     "$#{el.value}$"
    559   end
    560 end

convert_ol(el, opts)
Alias for: convert_ul
convert_p(el, opts) click to toggle source

       # File lib/kramdown/converter/latex.rb
    68 def convert_p(el, opts)
    69   if el.children.size == 1 && el.children.first.type == :img && !(img = convert_img(el.children.first, opts)).empty?
    70     convert_standalone_image(el, opts, img)
    71   else
    72     "#{latex_link_target(el)}#{inner(el, opts)}\n\n"
    73   end
    74 end

convert_raw(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    248 def convert_raw(el, opts)
    249   if !el.options[:type] || el.options[:type].empty? || el.options[:type].include?('latex')
    250     el.value + (el.options[:category] == :block ? "\n" : '')
    251   else
    252     ''
    253   end
    254 end

convert_root(el, opts) click to toggle source

       # File lib/kramdown/converter/latex.rb
    56 def convert_root(el, opts)
    57   inner(el, opts)
    58 end

convert_smart_quote(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    543 def convert_smart_quote(el, opts)
    544   res = entity_to_latex(smart_quote_entity(el)).chomp('{}')
    545   res << "{}" if ((nel = opts[:parent].children[opts[:index]+1]) && nel.type == :smart_quote) || res =~ /\w$/
    546   res
    547 end

convert_standalone_image(el, opts, img) click to toggle source

Helper method used by `convert_p` to convert a paragraph that only contains a single :img element.

       # File lib/kramdown/converter/latex.rb
    78 def convert_standalone_image(el, opts, img)
    79   attrs = attribute_list(el)
    80   "\\begin{figure}#{attrs}\n\\begin{center}\n#{img}\n\\end{center}\n\\caption{#{escape(el.children.first.attr['alt'])}}\n#{latex_link_target(el, true)}\n\\end{figure}#{attrs}\n"
    81 end

convert_strong(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    260 def convert_strong(el, opts)
    261   "\\textbf{#{latex_link_target(el)}#{inner(el, opts)}}"
    262 end

convert_table(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    172 def convert_table(el, opts)
    173   @data[:packages] << 'longtable'
    174   align = el.options[:alignment].map {|a| TABLE_ALIGNMENT_CHAR[a]}.join('|')
    175   attrs = attribute_list(el)
    176   "#{latex_link_target(el)}\\begin{longtable}{|#{align}|}#{attrs}\n\\hline\n#{inner(el, opts)}\\hline\n\\end{longtable}#{attrs}\n\n"
    177 end

convert_tbody(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    183 def convert_tbody(el, opts)
    184   inner(el, opts)
    185 end

convert_td(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    195 def convert_td(el, opts)
    196   inner(el, opts)
    197 end

convert_text(el, opts) click to toggle source

       # File lib/kramdown/converter/latex.rb
    64 def convert_text(el, opts)
    65   escape(el.value)
    66 end

convert_tfoot(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    187 def convert_tfoot(el, opts)
    188   "\\hline \\hline \n#{inner(el, opts)}"
    189 end

convert_thead(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    179 def convert_thead(el, opts)
    180   "#{inner(el, opts)}\\hline\n"
    181 end

convert_tr(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    191 def convert_tr(el, opts)
    192   el.children.map {|c| send("convert_#{c.type}", c, opts)}.join(' & ') << "\\\\\n"
    193 end

convert_typographic_sym(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    535 def convert_typographic_sym(el, opts)
    536   if (result = @options[:typographic_symbols][el.value])
    537     escape(result)
    538   else
    539     TYPOGRAPHIC_SYMS[el.value]
    540   end
    541 end

convert_ul(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    124 def convert_ul(el, opts)
    125   if !@data[:has_toc] && (el.options[:ial][:refs].include?('toc') rescue nil)
    126     @data[:has_toc] = true
    127     '\tableofcontents'
    128   else
    129     latex_environment(el.type == :ul ? 'itemize' : 'enumerate', el, inner(el, opts))
    130   end
    131 end

Also aliased as: convert_ol
convert_xml_comment(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    161 def convert_xml_comment(el, opts)
    162   el.value.split(/\n/).map {|l| "% #{l}"}.join("\n") + "\n"
    163 end

convert_xml_pi(el, opts) click to toggle source

        # File lib/kramdown/converter/latex.rb
    165 def convert_xml_pi(el, opts)
    166   warning("Can't convert XML PI")
    167   ''
    168 end

entity_to_latex(entity) click to toggle source

        # File lib/kramdown/converter/latex.rb
    515 def entity_to_latex(entity)
    516   text, package = ENTITY_CONV_TABLE[entity.code_point]
    517   if text
    518     @data[:packages] << package if package
    519     text
    520   else
    521     warning("Couldn't find entity with code #{entity.code_point} in substitution table!")
    522     ''
    523   end
    524 end

escape(str) click to toggle source

Escape the special LaTeX characters in the string `str`.

        # File lib/kramdown/converter/latex.rb
    611 def escape(str)
    612   str.gsub(ESCAPE_RE) {|m| ESCAPE_MAP[m]}
    613 end

inner(el, opts) click to toggle source

Return the converted content of the children of `el` as a string.

       # File lib/kramdown/converter/latex.rb
    45 def inner(el, opts)
    46   result = ''
    47   options = opts.dup.merge(:parent => el)
    48   el.children.each_with_index do |inner_el, index|
    49     options[:index] = index
    50     options[:result] = result
    51     result << send("convert_#{inner_el.type}", inner_el, options)
    52   end
    53   result
    54 end

latex_environment(type, el, text) click to toggle source

Wrap the `text` inside a LaTeX environment of type `type`. The element `el` is passed on to the method `attribute_list` – the resulting string is appended to both the \begin and the \end lines of the LaTeX environment for easier post-processing of LaTeX environments.

        # File lib/kramdown/converter/latex.rb
    575 def latex_environment(type, el, text)
    576   attrs = attribute_list(el)
    577   "\\begin{#{type}}#{latex_link_target(el)}#{attrs}\n#{text.rstrip}\n\\end{#{type}}#{attrs}\n"
    578 end

latex_link_target(el, add_label = false) click to toggle source

Return a string containing a valid hypertarget command if the element has an ID defined, or `nil` otherwise. If the parameter `add_label` is `true`, a label command will also be used additionally to the hypertarget command.

        # File lib/kramdown/converter/latex.rb
    583 def latex_link_target(el, add_label = false)
    584   if (id = el.attr['id'])
    585     "\\hypertarget{#{id}}{}" << (add_label ? "\\label{#{id}}" : '')
    586   else
    587     nil
    588   end
    589 end

normalize_abbreviation_key(key) click to toggle source

Normalize the abbreviation key so that it only contains allowed ASCII character

        # File lib/kramdown/converter/latex.rb
    568 def normalize_abbreviation_key(key)
    569   key.gsub(/\W/) {|m| m.unpack('H*').first}
    570 end