e9de0f0e22
Currently these are "transparent" containers, except in HTML, where they produce div and span elements with attributes.
320 lines
8.3 KiB
Lua
320 lines
8.3 KiB
Lua
-- This is a sample custom writer for pandoc. It produces output
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-- that is very similar to that of pandoc's HTML writer.
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-- There is one new feature: code blocks marked with class 'dot'
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-- are piped through graphviz and images are included in the HTML
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-- output using 'data:' URLs.
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--
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-- Invoke with: pandoc -t sample.lua
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--
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-- Note: you need not have lua installed on your system to use this
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-- custom writer. However, if you do have lua installed, you can
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-- use it to test changes to the script. 'lua sample.lua' will
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-- produce informative error messages if your code contains
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-- syntax errors.
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-- Character escaping
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local function escape(s, in_attribute)
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return s:gsub("[<>&\"']",
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function(x)
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if x == '<' then
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return '<'
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elseif x == '>' then
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return '>'
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elseif x == '&' then
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return '&'
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elseif x == '"' then
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return '"'
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elseif x == "'" then
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return '''
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else
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return x
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end
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end)
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end
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-- Helper function to convert an attributes table into
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-- a string that can be put into HTML tags.
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local function attributes(attr)
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local attr_table = {}
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for x,y in pairs(attr) do
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if y and y ~= "" then
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table.insert(attr_table, ' ' .. x .. '="' .. escape(y,true) .. '"')
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end
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end
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return table.concat(attr_table)
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end
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-- Run cmd on a temporary file containing inp and return result.
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local function pipe(cmd, inp)
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local tmp = os.tmpname()
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local tmph = io.open(tmp, "w")
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tmph:write(inp)
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tmph:close()
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local outh = io.popen(cmd .. " " .. tmp,"r")
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local result = outh:read("*all")
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outh:close()
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os.remove(tmp)
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return result
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end
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-- Table to store footnotes, so they can be included at the end.
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local notes = {}
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-- Blocksep is used to separate block elements.
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function Blocksep()
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return "\n\n"
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end
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-- This function is called once for the whole document. Parameters:
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-- body is a string, metadata is a table, variables is a table.
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-- One could use some kind of templating
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-- system here; this just gives you a simple standalone HTML file.
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function Doc(body, metadata, variables)
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local buffer = {}
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local function add(s)
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table.insert(buffer, s)
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end
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add('<!DOCTYPE html>')
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add('<html>')
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add('<head>')
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add('<title>' .. (metadata['title'] or '') .. '</title>')
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add('</head>')
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add('<body>')
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if metadata['title'] and metadata['title'] ~= "" then
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add('<h1 class="title">' .. metadata['title'] .. '</h1>')
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end
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for _, author in pairs(metadata['author'] or {}) do
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add('<h2 class="author">' .. author .. '</h2>')
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end
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if metadata['date'] and metadata['date'] ~= "" then
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add('<h3 class="date">' .. metadata.date .. '</h3>')
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end
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add(body)
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if #notes > 0 then
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add('<ol class="footnotes">')
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for _,note in pairs(notes) do
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add(note)
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end
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add('</ol>')
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end
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add('</body>')
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add('</html>')
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return table.concat(buffer,'\n')
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end
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-- The functions that follow render corresponding pandoc elements.
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-- s is always a string, attr is always a table of attributes, and
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-- items is always an array of strings (the items in a list).
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-- Comments indicate the types of other variables.
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function Str(s)
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return escape(s)
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end
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function Space()
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return " "
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end
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function LineBreak()
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return "<br/>"
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end
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function Emph(s)
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return "<em>" .. s .. "</em>"
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end
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function Strong(s)
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return "<strong>" .. s .. "</strong>"
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end
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function Subscript(s)
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return "<sub>" .. s .. "</sub>"
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end
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function Superscript(s)
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return "<sup>" .. s .. "</sup>"
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end
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function SmallCaps(s)
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return '<span style="font-variant: small-caps;">' .. s .. '</span>'
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end
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function Strikeout(s)
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return '<del>' .. s .. '</del>'
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end
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function Link(s, src, tit)
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return "<a href='" .. escape(src,true) .. "' title='" ..
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escape(tit,true) .. "'>" .. s .. "</a>"
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end
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function Image(s, src, tit)
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return "<img src='" .. escape(src,true) .. "' title='" ..
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escape(tit,true) .. "'/>"
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end
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function Code(s, attr)
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return "<code" .. attributes(attr) .. ">" .. escape(s) .. "</code>"
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end
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function InlineMath(s)
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return "\\(" .. escape(s) .. "\\)"
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end
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function DisplayMath(s)
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return "\\[" .. escape(s) .. "\\]"
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end
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function Note(s)
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local num = #notes + 1
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-- insert the back reference right before the final closing tag.
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s = string.gsub(s,
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'(.*)</', '%1 <a href="#fnref' .. num .. '">↩</a></')
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-- add a list item with the note to the note table.
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table.insert(notes, '<li id="fn' .. num .. '">' .. s .. '</li>')
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-- return the footnote reference, linked to the note.
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return '<a id="fnref' .. num .. '" href="#fn' .. num ..
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'"><sup>' .. num .. '</sup></a>'
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end
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function Span(s, attr)
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return "<span" .. attributes(attr) .. ">" .. s .. "</span>"
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end
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function Plain(s)
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return s
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end
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function Para(s)
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return "<p>" .. s .. "</p>"
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end
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-- lev is an integer, the header level.
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function Header(lev, s, attr)
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return "<h" .. lev .. attributes(attr) .. ">" .. s .. "</h" .. lev .. ">"
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end
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function BlockQuote(s)
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return "<blockquote>\n" .. s .. "\n</blockquote>"
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end
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function HorizontalRule()
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return "<hr/>"
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end
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function CodeBlock(s, attr)
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-- If code block has class 'dot', pipe the contents through dot
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-- and base64, and include the base64-encoded png as a data: URL.
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if attr.class and string.match(' ' .. attr.class .. ' ',' dot ') then
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local png = pipe("base64", pipe("dot -Tpng", s))
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return '<img src="data:image/png;base64,' .. png .. '"/>'
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-- otherwise treat as code (one could pipe through a highlighter)
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else
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return "<pre><code" .. attributes(attr) .. ">" .. escape(s) ..
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"</code></pre>"
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end
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end
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function BulletList(items)
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local buffer = {}
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for _, item in pairs(items) do
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table.insert(buffer, "<li>" .. item .. "</li>")
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end
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return "<ul>\n" .. table.concat(buffer, "\n") .. "\n</ul>"
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end
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function OrderedList(items)
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local buffer = {}
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for _, item in pairs(items) do
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table.insert(buffer, "<li>" .. item .. "</li>")
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end
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return "<ol>\n" .. table.concat(buffer, "\n") .. "\n</ol>"
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end
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-- Revisit association list STackValue instance.
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function DefinitionList(items)
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local buffer = {}
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for _,item in pairs(items) do
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for k, v in pairs(item) do
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table.insert(buffer,"<dt>" .. k .. "</dt>\n<dd>" ..
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table.concat(v,"</dd>\n<dd>") .. "</dd>")
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end
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end
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return "<dl>\n" .. table.concat(buffer, "\n") .. "\n</dl>"
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end
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-- Convert pandoc alignment to something HTML can use.
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-- align is AlignLeft, AlignRight, AlignCenter, or AlignDefault.
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function html_align(align)
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if align == 'AlignLeft' then
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return 'left'
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elseif align == 'AlignRight' then
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return 'right'
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elseif align == 'AlignCenter' then
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return 'center'
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else
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return 'left'
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end
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end
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-- Caption is a string, aligns is an array of strings,
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-- widths is an array of floats, headers is an array of
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-- strings, rows is an array of arrays of strings.
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function Table(caption, aligns, widths, headers, rows)
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local buffer = {}
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local function add(s)
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table.insert(buffer, s)
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end
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add("<table>")
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if caption ~= "" then
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add("<caption>" .. caption .. "</caption>")
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end
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if widths and widths[1] ~= 0 then
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for _, w in pairs(widths) do
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add('<col width="' .. string.format("%d%%", w * 100) .. '" />')
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end
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end
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local header_row = {}
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local empty_header = true
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for i, h in pairs(headers) do
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local align = html_align(aligns[i])
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table.insert(header_row,'<th align="' .. align .. '">' .. h .. '</th>')
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empty_header = empty_header and h == ""
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end
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if empty_header then
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head = ""
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else
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add('<tr class="header">')
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for _,h in pairs(header_row) do
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add(h)
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end
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add('</tr>')
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end
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local class = "even"
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for _, row in pairs(rows) do
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class = (class == "even" and "odd") or "even"
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add('<tr class="' .. class .. '">')
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for i,c in pairs(row) do
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add('<td align="' .. html_align(aligns[i]) .. '">' .. c .. '</td>')
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end
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add('</tr>')
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end
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add('</table')
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return table.concat(buffer,'\n')
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end
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function Div(s, attr)
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return "<div" .. attributes(attr) .. ">\n" .. s .. "</div>"
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end
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-- The following code will produce runtime warnings when you haven't defined
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-- all of the functions you need for the custom writer, so it's useful
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-- to include when you're working on a writer.
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local meta = {}
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meta.__index =
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function(_, key)
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io.stderr:write(string.format("WARNING: Undefined function '%s'\n",key))
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return function() return "" end
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end
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setmetatable(_G, meta)
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