markdown (30dec21)

git-svn-id: svn://tug.org/texlive/trunk@61448 c570f23f-e606-0410-a88d-b1316a301751

1 files changed, 393 insertions, 48 deletions

diff --git a/Master/texmf-dist/source/generic/markdown/markdown.dtx b/Master/texmf-dist/source/generic/markdown/markdown.dtx
index fad63a37918..b624b048799 100644
--- a/Master/texmf-dist/source/generic/markdown/markdown.dtx
+++ b/Master/texmf-dist/source/generic/markdown/markdown.dtx
@@ -4,8 +4,11 @@
 \documentclass{ltxdockit}
 \usepackage[american]{babel}
 \usepackage{amsmath,btxdockit,doc,fancyvrb,graphicx,hologo,microtype,minted,varioref}
+\vrefwarning
 
 % Set up the style.
+\usepackage{xcolor}
+\definecolor{spot}{rgb}{0,0.2,0.6}
 \usepackage{fontspec}
 \defaultfontfeatures[\rmfamily,\sffamily,\ttfamily]{}
 \emergencystretch=1em
@@ -83,10 +86,10 @@
   html,
   jekyllData,
   stripPercentSigns,
-  underscores=false,
-  theme=witiko/dot,
-  theme=witiko/graphicx/http,
-  theme=witiko/markdown/techdoc,
+  underscores = false,
+  theme = witiko/dot,
+  theme = witiko/graphicx/http,
+  theme = witiko/markdown/techdoc,
 ]{markdown}
 
 % Set up Unicode characters.
@@ -720,13 +723,26 @@ abbr {
   pagetotal = {xviii, 347},
   location  = {Rio de Janeiro},
   publisher = {PUC-Rio}}
-@book{knuth86,
+@book{knuth86a,
   author    = {Knuth, Donald Ervin},
   year      = {1986},
   title     = {The \TeX{}book},
   edition   = {3},
   isbn      = {0-201-13447-0},
   pagetotal = {ix, 479},
+  series    = {Computers \& Typesetting},
+  volume    = {A},
+  location  = {Reading, MA},
+  publisher = {Addison-Wesley}}
+@book{knuth86b,
+  author    = {Knuth, Donald Ervin},
+  year      = {1986},
+  title     = {\TeX: The Program},
+  isbn      = {0-201-13437-7},
+  pagetotal = {xvi, 594},
+  series    = {Computers \& Typesetting},
+  volume    = {B},
+  location  = {Reading, MA},
   publisher = {Addison-Wesley}}
 @online{novotny21,
   author    = {Novotný, Vít},
@@ -734,6 +750,15 @@ abbr {
   date      = {2021-02-20},
   url       = {https://github.com/latex3/latex2e/issues/510},
   urldate   = {2021-02-21}}
+@book{eijkhout92,
+  author    = {Victor Eijkhout},
+  title     = {\TeX{} by Topic},
+  subtitle  = {A \TeX nician's Reference},
+  isbn      = {0-201-56882-0},
+  pagetotal = {307},
+  date = {1992-02-01},
+  location = {Wokingham, England},
+  publisher = {Addison-Wesley}}
 %</techdoc-bibliography>
 %<*latex-themes-witiko-markdown-techdoc>
 \ProvidesPackage{markdownthemewitiko_markdown_techdoc}[2021/09/10]
@@ -3838,6 +3863,97 @@ defaultOptions.definitionLists = false
 %</lua,lua-cli>
 %<*manual-options>
 
+#### Option `eagerCache`
+
+`eagerCache` (default value: `true`)
+
+% \fi
+% \begin{markdown}
+%
+% \Optitem[true]{eagerCache}{\opt{true}, \opt{false}}
+%
+:    true
+
+     Converted markdown documents will be cached in \Opt{cacheDir}. This can be
+     useful for post-processing the converted documents and for recovering
+     historical versions of the documents from the cache.  However, it also
+     produces a large number of auxiliary files on the disk and obscures the
+     output of the Lua command-line interface when it is used for plumbing.
+
+     This behavior will always be used if the \Opt{finalizeCache} option is
+     enabled.
+
+:    false
+
+     Converted markdown documents will not be cached. This decreases the number
+     of auxiliary files that we produce and makes it easier to use the Lua
+     command-line interface for plumbing.
+
+     This behavior will only be used when the \Opt{finalizeCache} option is
+     disabled. Furthermore, this behavior is planned to be the new default in
+     the next major release of the Markdown package.
+
+% \end{markdown}
+% \iffalse
+
+##### Lua Module Example {.unnumbered}
+
+Using a text editor, create a text document named `hello.md` with the
+following content:
+``` md
+Hello *world*!
+``````
+Next, invoke LuaTeX from the terminal with the \Opt{eagerCache} option
+disabled:
+``` sh
+texlua ⟨CLI pathname⟩ eagerCache=false -- hello.md hello.tex
+```````
+where \meta{CLI pathname} corresponds to the location of the Lua CLI script file,
+such as `~/texmf/scripts/markdown/markdown-cli.lua` on UN\*X systems or
+`C:\Users\`\meta{Your username}`\texmf\scripts\markdown\markdown-cli.lua` on Windows
+systems. Use the command `kpsewhich -a markdown-cli.lua` to locate the Lua CLI
+script file using [Kpathsea][].
+
+A \TeX{} document named `hello.tex` should be produced and contain the
+following code:
+``` tex
+Hello \markdownRendererEmphasis{world}!\relax
+```
+
+***
+
+Invoke LuaTeX from the terminal again, this time with the \Opt{eagerCache}
+option enabled:
+
+``` tex
+texlua ⟨CLI pathname⟩ eagerCache=true -- hello.md hello.tex
+```
+
+A \TeX{} document named `hello.tex` should be produced and contain the
+following code:
+
+``` tex
+\input ./⟨hash⟩.md.tex\relax
+```
+
+Additionally, a \TeX{} document named `⟨hash⟩.md.tex` should be produced and
+contain the following code:
+
+``` tex
+Hello \markdownRendererEmphasis{world}!\relax
+```
+
+%</manual-options>
+%<*lua,lua-cli>
+% \fi
+%  \begin{macrocode}
+defaultOptions.eagerCache = true
+%    \end{macrocode}
+% \par
+% \iffalse
+%</lua,lua-cli>
+%<*manual-options>
+
 #### Option `fencedCode`
 
 `fencedCode` (default value: `false`)
@@ -4364,6 +4480,80 @@ defaultOptions.frozenCacheCounter = 0
 %</lua,lua-cli>
 %<*manual-options>
 
+#### Option `hardLineBreaks`
+
+`hardLineBreaks` (default value: `false`)
+
+% \fi
+% \begin{markdown}
+%
+% \Optitem[false]{hardLineBreaks}{\opt{true}, \opt{false}}
+%
+:    true
+
+     :  Interpret all newlines within a paragraph as hard line breaks instead
+        of spaces.
+
+:    false
+
+     :  Interpret all newlines within a paragraph as spaces.
+
+% \end{markdown}
+% \iffalse
+
+##### \LaTeX{} Example {.unnumbered}
+
+Using a text editor, create a text document named `document.tex` with the
+following content:
+``` tex
+\documentclass{article}
+\usepackage{markdown}
+\begin{document}
+
+\begin{markdown}
+'Twas brillig, and the slithy toves
+Did gyre and gimble in the wabe;
+All mimsy were the borogoves,
+And the mome raths outgrabe.
+\end{markdown}
+
+\begin{markdown*}{hardLineBreaks}
+'Twas brillig, and the slithy toves
+Did gyre and gimble in the wabe;
+All mimsy were the borogoves,
+And the mome raths outgrabe.
+\end{markdown*}
+
+\end{document}
+```````
+Next, invoke LuaTeX from the terminal:
+``` sh
+lualatex document.tex
+``````
+A PDF document named `document.pdf` should be produced and contain the
+following text:
+
+> 'Twas brillig, and the slithy toves
+> Did gyre and gimble in the wabe;
+> All mimsy were the borogoves,
+> And the mome raths outgrabe.
+>
+> 'Twas brillig, and the slithy toves  
+> Did gyre and gimble in the wabe;  
+> All mimsy were the borogoves,  
+> And the mome raths outgrabe.
+
+%</manual-options>
+%<*lua,lua-cli>
+% \fi
+%  \begin{macrocode}
+defaultOptions.hardLineBreaks = false
+%    \end{macrocode}
+% \par
+% \iffalse
+%</lua,lua-cli>
+%<*manual-options>
+
 #### Option `hashEnumerators`
 
 `hashEnumerators` (default value: `false`)
@@ -6983,7 +7173,7 @@ pdftex --shell-escape document.tex
 % Another limitation concerns spaces at the right end of an input line. In
 % markdown, these are used to produce a forced line break. However, any such
 % spaces are removed before the lines enter the input buffer of
-% \TeX{}~[@knuth86, p. 46]. As a corrolary, the \mref{markdownBegin} macro also
+% \TeX{}~[@knuth86a, p. 46]. As a corrolary, the \mref{markdownBegin} macro also
 % ignores them.
 %
 % The \mref{markdownBegin} and \mref{markdownEnd} macros will also consume the rest
@@ -7057,6 +7247,16 @@ the `markdown` Lua module. They are supported by all higher-level interfaces of
 the Markdown package, i.e. the plain \TeX{}, \LaTeX{} and \Hologo{ConTeXt}
 interfaces.
 
+#### Setting Lua options from plain \TeX{}
+
+As a rule of thumb, you can set all Lua options directly from plain \TeX{}. For
+example, to set the \Opt{taskLists} Lua option to `true`, you would include the
+following code in your plain \TeX{} document:
+
+``` tex
+\def\markdownOptionTaskLists{true}
+```
+
 %</manual-options>
 %<*tex>
 % \fi
@@ -7096,7 +7296,7 @@ defaults to `false`.
 
 % The standard usage of the above two options is as follows:
 % \iffalse
-The standard usage of the \Opt{finalizeCache} and \mref{markdownOptionFrozenCache}
+The standard usage of the \Opt{finalizeCache} and \Opt{frozenCache}
 options is as follows:
 % \fi
 
@@ -7241,6 +7441,9 @@ Markdown to \TeX{}:
 - `\markdownOptionCacheDir`, and
 - `\markdownOptionFrozenCacheFileName`.
 
+The `\markdownOptionCacheDir` and `\markdownOptionFrozenCacheFileName` commands
+correspond to the `cacheDir` and `frozenCacheFileName` Lua options.
+
 Using a text editor, create a folder named `output-directory` and a text
 document named `document.tex` with the following content:
 ``` tex
@@ -7313,8 +7516,10 @@ bug](https://github.com/witiko/markdown/issues).
 \let\markdownOptionContentBlocks\undefined
 \let\markdownOptionContentBlocksLanguageMap\undefined
 \let\markdownOptionDefinitionLists\undefined
+\let\markdownOptionEagerCache\undefined
 \let\markdownOptionFootnotes\undefined
 \let\markdownOptionFencedCode\undefined
+\let\markdownOptionHardLineBreaks\undefined
 \let\markdownOptionHashEnumerators\undefined
 \let\markdownOptionHeaderAttributes\undefined
 \let\markdownOptionHtml\undefined
@@ -10512,6 +10717,30 @@ arguments: the scalar key in the parent structure, cast to a string following
 %
 % \begin{markdown}
 
+The \mdef{markdownRendererJekyllDataSequenceEnd} macro represents the
+end of a sequence in a \acro{yaml} document. This macro will only be produced
+when the \Opt{jekyllData} option is enabled. The macro receives no arguments.
+
+% \end{markdown}
+%
+% \iffalse
+%</manual-tokens>
+%<*tex>
+% \fi
+%
+%  \begin{macrocode}
+\def\markdownRendererJekyllDataSequenceEnd{%
+  \markdownRendererJekyllDataSequenceEndPrototype}%
+%    \end{macrocode}
+% \par
+%
+% \iffalse
+%</tex>
+%<*manual-tokens>
+% \fi
+%
+% \begin{markdown}
+
 The \mdef{markdownRendererJekyllDataBoolean} macro represents a boolean scalar
 value in a \acro{yaml} document. This macro will only be produced when the
 \Opt{jekyllData} option is enabled. The macro receives two arguments: the
@@ -11959,11 +12188,11 @@ pdflatex --shell-escape document.tex
 % \documentclass{article}            \documentclass{article}
 % \usepackage{markdown}              \usepackage{markdown}
 % \begin{document}                   \begin{document}
-% % ...                              % ...
+% \% ...                              \% ...
 % \begin{markdown}                   \begin{markdown*}{smartEllipses}
 % _Hello_ **world** ...              _Hello_ **world** ...
 % \end{markdown}                     \end{markdown*}
-% % ...                              % ...
+% \% ...                              \% ...
 % \end{document}                     \end{document}
 % ```````
 %
@@ -12054,6 +12283,29 @@ pdflatex --shell-escape document.tex
 prototypes from plain \TeX{}, load user-contributed themes, and invoke
 user-defined setup snippets.
 
+#### Setting Lua and plain \TeX{} options from \LaTeX{}
+
+As a rule of thumb, we can set all Lua options directly from \LaTeX{}. For
+example, to set the \Opt{taskLists} Lua option to `true`, we would include the
+following code in our \LaTeX{} document:
+
+``` tex
+\markdownSetup{
+  taskLists = true,
+}
+```
+
+We can also set all plain \TeX{} options directly from \LaTeX{}. For example,
+to set the `\markdownOptionHelperScriptFileName` plain \TeX{} option to
+`helper-script.lua`, we would inclde the following code in our \LaTeX{}
+document:
+
+``` tex
+\markdownSetup{
+  helperScriptFileName = helper-script.lua,
+}
+```
+
 % \fi
 % \par
 % \begin{markdown}
@@ -12064,9 +12316,11 @@ Default token renderer prototypes require \LaTeX{} packages that may clash with
 other packages used in a document.  Additionally, if we redefine token
 renderers and renderer prototypes ourselves, the default definitions will bring
 no benefit to us. Using the `plain` package option, we can keep the default
-definitions from the plain \TeX{} implementation (see Section
-\vref{sec:textokenrendererprototypes}) and prevent the soft \LaTeX{}
-prerequisites in Section \vref{sec:latexprerequisites} from being loaded:
+definitions from the plain \TeX{} implementation
+% (see Section \vref{sec:textokenrendererprototypes})
+and prevent the soft \LaTeX{} prerequisites
+% in Section \vref{sec:latexprerequisites}
+from being loaded:
 
 ``` tex
 \usepackage[plain]{markdown}
@@ -12584,12 +12838,16 @@ The following ordered list will be preceded by roman numerals:
   \def\markdownOptionContentBlocksLanguageMap{#1}}%
 \define@key{markdownOptions}{definitionLists}[true]{%
   \def\markdownOptionDefinitionLists{#1}}%
+\define@key{markdownOptions}{eagerCache}[true]{%
+  \def\markdownOptionEagerCache{#1}}%
 \define@key{markdownOptions}{footnotes}[true]{%
   \def\markdownOptionFootnotes{#1}}%
 \define@key{markdownOptions}{fencedCode}[true]{%
   \def\markdownOptionFencedCode{#1}}%
 \define@key{markdownOptions}{jekyllData}[true]{%
   \def\markdownOptionJekyllData{#1}}%
+\define@key{markdownOptions}{hardLineBreaks}[true]{%
+  \def\markdownOptionHardLineBreaks{#1}}%
 \define@key{markdownOptions}{hashEnumerators}[true]{%
   \def\markdownOptionHashEnumerators{#1}}%
 \define@key{markdownOptions}{headerAttributes}[true]{%
@@ -12844,8 +13102,8 @@ The following ordered list will be preceded by roman numerals:
 % ``` tex
 % \markdownSetup{
 %   renderers = {
-%     link = {#4},                   % Render links as the link title.
-%     emphasis = {\emph{#1}},    % Render emphasized text via `\emph`.
+%     link = {#4},                   \% Render links as the link title.
+%     emphasis = {\emph{#1}},    \% Render emphasized text via `\emph`.
 %   }
 % }
 % ```````
@@ -13016,7 +13274,7 @@ The following ordered list will be preceded by roman numerals:
 % \markdownSetup{
 %   rendererPrototypes = {
 %     image = {\includegraphics{#2}},
-%     codeSpan = {\texttt{#1}},    % Render inline code via `\texttt`.
+%     codeSpan = {\texttt{#1}},    \% Render inline code via `\texttt`.
 %   }
 % }
 % ```````
@@ -15712,7 +15970,7 @@ function M.writer.new(options)
 % \end{markdown}
 %  \begin{macrocode}
   function self.pack(name)
-    return [[\input ]] .. name .. [[\relax{}]]
+    return [[\input ]] .. name .. [[\relax]]
   end
 %    \end{macrocode}
 % \par
@@ -17841,15 +18099,22 @@ larsers.PipeTable = Ct(larsers.table_row * parsers.newline
                       + larsers.bqstart
                       + larsers.headerstart
                       + larsers.fencestart
-                    ) * parsers.spacechar^0 / writer.space
+                    ) * parsers.spacechar^0
+                    / (options.hardLineBreaks and writer.linebreak
+                                               or writer.space)
 
   larsers.OptionalIndent
                      = parsers.spacechar^1 / writer.space
 
   larsers.Space      = parsers.spacechar^2 * larsers.Endline / writer.linebreak
                      + parsers.spacechar^1 * larsers.Endline^-1 * parsers.eof / ""
-                     + parsers.spacechar^1 * larsers.Endline^-1
-                                           * parsers.optionalspace / writer.space
+                     + parsers.spacechar^1 * larsers.Endline
+                                           * parsers.optionalspace
+                                           / (options.hardLineBreaks
+                                              and writer.linebreak
+                                               or writer.space)
+                     + parsers.spacechar^1 * parsers.optionalspace
+                                           / writer.space
 
   larsers.NonbreakingEndline
                     = parsers.newline * -( -- newline, but not before...
@@ -17859,13 +18124,20 @@ larsers.PipeTable = Ct(larsers.table_row * parsers.newline
                       + larsers.bqstart
                       + larsers.headerstart
                       + larsers.fencestart
-                    ) * parsers.spacechar^0 / writer.nbsp
+                    ) * parsers.spacechar^0
+                    / (options.hardLineBreaks and writer.linebreak
+                                               or writer.nbsp)
 
   larsers.NonbreakingSpace
                   = parsers.spacechar^2 * larsers.Endline / writer.linebreak
                   + parsers.spacechar^1 * larsers.Endline^-1 * parsers.eof / ""
-                  + parsers.spacechar^1 * larsers.Endline^-1
-                                        * parsers.optionalspace / writer.nbsp
+                  + parsers.spacechar^1 * larsers.Endline
+                                        * parsers.optionalspace
+                                        / (options.hardLineBreaks
+                                           and writer.linebreak
+                                            or writer.nbsp)
+                  + parsers.spacechar^1 * parsers.optionalspace
+                                        / writer.nbsp
 
   if options.underscores then
     larsers.Strong = ( parsers.between(parsers.Inline, parsers.doubleasterisks,
@@ -18437,19 +18709,30 @@ larsers.PipeTable = Ct(larsers.table_row * parsers.newline
     end
     table.sort(opt_string)
     local salt = table.concat(opt_string, ",") .. "," .. metadata.version
+    local output
 %    \end{macrocode}
 % \begin{markdown}
-% Produce the cache file and transform its filename to plain \TeX{} output
-% via the \luamref{writer->pack} method.
+% If we cache markdown documents, produce the cache file and transform its
+% filename to plain \TeX{} output via the \luamref{writer->pack} method.
 % \end{markdown}
 %  \begin{macrocode}
-    local name = util.cache(options.cacheDir, input, salt, function(input)
-        return util.rope_to_string(parse_blocks_toplevel(input)) .. writer.eof
-      end, ".md" .. writer.suffix)
-    local output = writer.pack(name)
+    local function convert(input)
+      return util.rope_to_string(parse_blocks_toplevel(input)) .. writer.eof
+    end
+    if options.eagerCache or options.finalizeCache then
+      local name = util.cache(options.cacheDir, input, salt, convert, ".md" .. writer.suffix)
+      output = writer.pack(name)
 %    \end{macrocode}
 % \begin{markdown}
-% If the \Opt{frozenCache} option is enabled, populate the frozen cache in
+% Otherwise, return the result of the conversion directly.
+% \end{markdown}
+%  \begin{macrocode}
+    else
+      output = convert(input)
+    end
+%    \end{macrocode}
+% \begin{markdown}
+% If the \Opt{finalizeCache} option is enabled, populate the frozen cache in
 % the file \Opt{frozenCacheFileName} with an entry for markdown document
 % number \Opt{frozenCacheCounter}.
 % \end{markdown}
@@ -18731,6 +19014,9 @@ end
 \ifx\markdownOptionDefinitionLists\undefined\else
   definitionLists = \markdownOptionDefinitionLists,
 \fi
+\ifx\markdownOptionEagerCache\undefined\else
+  eagerCache = \markdownOptionEagerCache,
+\fi
 \ifx\markdownOptionFinalizeCache\undefined\else
   finalizeCache = \markdownOptionFinalizeCache,
 \fi
@@ -18742,6 +19028,9 @@ end
 \ifx\markdownOptionFencedCode\undefined\else
   fencedCode = \markdownOptionFencedCode,
 \fi
+\ifx\markdownOptionHardLineBreaks\undefined\else
+  hardLineBreaks = \markdownOptionHardLineBreaks,
+\fi
 \ifx\markdownOptionHashEnumerators\undefined\else
   hashEnumerators = \markdownOptionHashEnumerators,
 \fi
@@ -19226,7 +19515,28 @@ end
 %
 % \end{markdown}
 %  \begin{macrocode}
-\def\markdownLuaExecute#1{\directlua{local print = tex.print #1}}%
+\begingroup
+%    \end{macrocode}
+% \begin{markdown}
+% Swap the category code of the backslash symbol and the pipe symbol, so that
+% we may use the backslash symbol freely inside the Lua code.
+% \end{markdown}
+%  \begin{macrocode}
+  \catcode`|=0%
+  \catcode`\\=12%
+  |gdef|markdownLuaExecute#1{%
+    |directlua{%
+      local function print(input)
+        local output = {}
+        for line in input:gmatch("[^\r\n]+") do
+          table.insert(output, line)
+        end
+        tex.print(output)
+      end
+      #1
+    }%
+  }%
+|endgroup
 \fi
 %    \end{macrocode}
 % \par
@@ -19745,8 +20055,17 @@ end
         \ifx\empty#4\empty\else
           \caption{#4}%
         \fi
-      \end{table}}{%
-      \markdownInput{#3}}},
+      \end{table}%
+    }{%
+      \ifthenelse{\equal{#1}{tex}}{%
+        \catcode`\%=14\relax
+        \input #3\relax
+        \catcode`\%=12\relax
+      }{%
+        \markdownInput{#3}%
+      }%
+    }%
+  },
   image = {%
     \begin{figure}%
       \begin{center}%
@@ -20603,24 +20922,50 @@ end
 % The \mref{startmarkdown} and \mref{stopmarkdown} macros are implemented using the
 % \mref{markdownReadAndConvert} macro.
 %
+% In Knuth's \TeX, trailing spaces are removed very early on when a line is
+% being put to the input buffer.~[@knuth86b, sec. 31].  According to
+% @eijkhout92 [sec. 2.2], this is because ``these spaces are hard to see in
+% an editor''. At the moment, there is no option to suppress this behavior in
+% (Lua)\TeX, but \Hologo{ConTeXt} MkIV funnels all input through its own input
+% handler. This makes it possible to suppress the removal of trailing spaces
+% in \Hologo{ConTeXt} MkIV and therefore to insert hard line breaks into
+% markdown text.
+%
 % \end{markdown}
 %  \begin{macrocode}
-\begingroup
-%    \end{macrocode}
-% \begin{markdown}
-% Locally swap the category code of the backslash symbol with the pipe symbol.
-% This is required in order that all the special symbols that appear in the
-% first argument of the `markdownReadAndConvert` macro have the category code
-% *other*.
-% \end{markdown}
-%  \begin{macrocode}
-  \catcode`\|=0%
-  \catcode`\\=12%
-  |gdef|startmarkdown{%
-    |markdownReadAndConvert{\stopmarkdown}%
-                           {|stopmarkdown}}%
-  |gdef|stopmarkdown{|markdownEnd}%
-|endgroup
+\ifx\startluacode\undefined  % MkII
+  \begingroup
+    \catcode`\|=0%
+    \catcode`\\=12%
+    |gdef|startmarkdown{%
+      |markdownReadAndConvert{\stopmarkdown}%
+                             {|stopmarkdown}}%
+    |gdef|stopmarkdown{%
+      |markdownEnd}%
+  |endgroup
+\else  % MkIV
+  \startluacode
+    document.markdown_buffering = false
+    local function preserve_trailing_spaces(line)
+      if document.markdown_buffering then
+        line = line:gsub("[ \t][ \t]$", "\t\t")
+      end
+      return line
+    end
+    resolvers.installinputlinehandler(preserve_trailing_spaces)
+  \stopluacode
+  \begingroup
+    \catcode`\|=0%
+    \catcode`\\=12%
+    |gdef|startmarkdown{%
+      |ctxlua{document.markdown_buffering = true}%
+      |markdownReadAndConvert{\stopmarkdown}%
+                             {|stopmarkdown}}%
+    |gdef|stopmarkdown{%
+      |ctxlua{document.markdown_buffering = false}%
+      |markdownEnd}%
+  |endgroup
+\fi
 %    \end{macrocode}
 % \par
 % \begin{markdown}