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2020-01-10 :: Pandoc Lua Filters – Albert Krewinkel; John MacFarlane

Title: Pandoc Lua Filters

Date: 2020-01-10

Authors: Albert Krewinkel, John MacFarlane

Tags: (no tags)

Reading time: 13425 words, 61 minutes

2020-01-10 :: Pandoc Lua Filters – Albert Krewinkel; John MacFarlane

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Introduction

Pandoc has long supported filters, which allow the pandoc abstract syntax tree (AST) to be manipulated between the parsing and the writing phase. Traditional pandoc filters accept a JSON representation of the pandoc AST and produce an altered JSON representation of the AST. They may be written in any programming language, and invoked from pandoc using the --filter option.

Although traditional filters are very flexible, they have a couple of disadvantages. First, there is some overhead in writing JSON to stdout and reading it from stdin (twice, once on each side of the filter). Second, whether a filter will work will depend on details of the user’s environment. A filter may require an interpreter for a certain programming language to be available, as well as a library for manipulating the pandoc AST in JSON form. One cannot simply provide a filter that can be used by anyone who has a certain version of the pandoc executable.

Starting with version 2.0, pandoc makes it possible to write filters in Lua without any external dependencies at all. A Lua interpreter (version 5.3) and a Lua library for creating pandoc filters is built into the pandoc executable. Pandoc data types are marshaled to Lua directly, avoiding the overhead of writing JSON to stdout and reading it from stdin.

Here is an example of a Lua filter that converts strong emphasis to small caps:

return {
  {
    Strong = function (elem)
      return pandoc.SmallCaps(elem.c)
    end,
  }
}

or equivalently,

function Strong(elem)
  return pandoc.SmallCaps(elem.c)
end

This says: walk the AST, and when you find a Strong element, replace it with a SmallCaps element with the same content.

To run it, save it in a file, say smallcaps.lua, and invoke pandoc with --lua-filter=smallcaps.lua.

Here’s a quick performance comparison, converting the pandoc manual (MANUAL.txt) to HTML, with versions of the same JSON filter written in compiled Haskell (smallcaps) and interpreted Python (smallcaps.py):

Command Time
pandoc 1.01s
pandoc --filter ./smallcaps 1.36s
pandoc --filter ./smallcaps.py 1.40s
pandoc --lua-filter ./smallcaps.lua 1.03s

As you can see, the Lua filter avoids the substantial overhead associated with marshaling to and from JSON over a pipe.

Lua filter structure

Lua filters are tables with element names as keys and values consisting of functions acting on those elements.

Filters are expected to be put into separate files and are passed via the --lua-filter command-line argument. For example, if a filter is defined in a file current-date.lua, then it would be applied like this:

pandoc --lua-filter=current-date.lua -f markdown MANUAL.txt

The --lua-filter option may be supplied multiple times. Pandoc applies all filters (including JSON filters specified via --filter and Lua filters specified via --lua-filter) in the order they appear on the command line.

Pandoc expects each Lua file to return a list of filters. The filters in that list are called sequentially, each on the result of the previous filter. If there is no value returned by the filter script, then pandoc will try to generate a single filter by collecting all top-level functions whose names correspond to those of pandoc elements (e.g., Str, Para, Meta, or Pandoc). (That is why the two examples above are equivalent.)

For each filter, the document is traversed and each element subjected to the filter. Elements for which the filter contains an entry (i.e. a function of the same name) are passed to Lua element filtering function. In other words, filter entries will be called for each corresponding element in the document, getting the respective element as input.

The return value of a filter function must be one of the following:

  • nil: this means that the object should remain unchanged.
  • a pandoc object: this must be of the same type as the input and will replace the original object.
  • a list of pandoc objects: these will replace the original object; the list is merged with the neighbors of the original objects (spliced into the list the original object belongs to); returning an empty list deletes the object.

The function’s output must result in an element of the same type as the input. This means a filter function acting on an inline element must return either nil, an inline, or a list of inlines, and a function filtering a block element must return one of nil, a block, or a list of block elements. Pandoc will throw an error if this condition is violated.

If there is no function matching the element’s node type, then the filtering system will look for a more general fallback function. Two fallback functions are supported, Inline and Block. Each matches elements of the respective type.

Elements without matching functions are left untouched.

See module documentation for a list of pandoc elements.

Filters on element sequences

For some filtering tasks, it is necessary to know the order in which elements occur in the document. It is not enough then to inspect a single element at a time.

There are two special function names, which can be used to define filters on lists of blocks or lists of inlines.

Inlines (inlines)
If present in a filter, this function will be called on all lists of inline elements, like the content of a Para (paragraph) block, or the description of an Image. The inlines argument passed to the function will be a List of Inline elements for each call.
Blocks (blocks)
If present in a filter, this function will be called on all lists of block elements, like the content of a MetaBlocks meta element block, on each item of a list, and the main content of the Pandoc document. The blocks argument passed to the function will be a List of Block elements for each call.

These filter functions are special in that the result must either be nil, in which case the list is left unchanged, or must be a list of the correct type, i.e., the same type as the input argument. Single elements are not allowed as return values, as a single element in this context usually hints at a bug.

See “Remove spaces before normal citations” for an example.

This functionality has been added in pandoc 2.9.2.

Traversal order

The traversal order of filters can be selected by setting the key traverse to either 'topdown' or 'typewise'; the default is 'typewise'.

Example:

local filter = {
  traverse = 'topdown',
  -- ... filter functions ...
}
return {filter}

Support for this was added in pandoc 2.17; previous versions ignore the traverse setting.

Typewise traversal

Element filter functions within a filter set are called in a fixed order, skipping any which are not present:

  1. functions for Inline elements,
  2. the Inlines filter function,
  3. functions for Block elements ,
  4. the Blocks filter function,
  5. the Meta filter function, and last
  6. the Pandoc filter function.

It is still possible to force a different order by explicitly returning multiple filter sets. For example, if the filter for Meta is to be run before that for Str, one can write

-- ... filter definitions ...

return {
  { Meta = Meta },  -- (1)
  { Str = Str }     -- (2)
}

Filter sets are applied in the order in which they are returned. All functions in set (1) are thus run before those in (2), causing the filter function for Meta to be run before the filtering of Str elements is started.

Topdown traversal

It is sometimes more natural to traverse the document tree depth-first from the root towards the leaves, and all in a single run.

For example, a block list [Plain [Str "a"], Para [Str "b"]] will try the following filter functions, in order: Blocks, Plain, Inlines, Str, Para, Inlines, Str.

Topdown traversals can be cut short by returning false as a second value from the filter function. No child-element of the returned element is processed in that case.

For example, to exclude the contents of a footnote from being processed, one might write

traverse = 'topdown'
function Note (n)
  return n, false
end

Global variables

Pandoc passes additional data to Lua filters by setting global variables.

FORMAT
The global FORMAT is set to the format of the pandoc writer being used (html5, latex, etc.), so the behavior of a filter can be made conditional on the eventual output format.
PANDOC_READER_OPTIONS
Table of the options which were provided to the parser. (ReaderOptions)
PANDOC_WRITER_OPTIONS

Table of the options that will be passed to the writer. While the object can be modified, the changes will not be picked up by pandoc. (WriterOptions)

This variable is also set in custom writers.

Since: pandoc 2.17

PANDOC_VERSION
Contains the pandoc version as a Version object which behaves like a numerically indexed table, most significant number first. E.g., for pandoc 2.7.3, the value of the variable is equivalent to a table {2, 7, 3}. Use tostring(PANDOC_VERSION) to produce a version string. This variable is also set in custom writers.
PANDOC_API_VERSION
Contains the version of the pandoc-types API against which pandoc was compiled. It is given as a numerically indexed table, most significant number first. E.g., if pandoc was compiled against pandoc-types 1.17.3, then the value of the variable will behave like the table {1, 17, 3}. Use tostring(PANDOC_API_VERSION) to produce a version string. This variable is also set in custom writers.
PANDOC_SCRIPT_FILE
The name used to involve the filter. This value can be used to find files relative to the script file. This variable is also set in custom writers.
PANDOC_STATE
The state shared by all readers and writers. It is used by pandoc to collect and pass information. The value of this variable is of type CommonState and is read-only.
pandoc
The pandoc module, described in the next section, is available through the global pandoc. The other modules described herein are loaded as subfields under their respective name.
lpeg

This variable holds the lpeg module, a package based on Parsing Expression Grammars (PEG). It provides excellent parsing utilities and is documented on the official LPeg homepage. Pandoc uses a built-in version of the library, unless it has been configured by the package maintainer to rely on a system-wide installation.

Note that the result of require 'lpeg' is not necessarily equal to this value; the require mechanism prefers the system’s lpeg library over the built-in version.

re

Contains the LPeg.re module, which is built on top of LPeg and offers an implementation of a regex engine. Pandoc uses a built-in version of the library, unless it has been configured by the package maintainer to rely on a system-wide installation.

Note that the result of require 're is not necessarily equal to this value; the require mechanism prefers the system’s lpeg library over the built-in version.

Pandoc Module

The pandoc Lua module is loaded into the filter’s Lua environment and provides a set of functions and constants to make creation and manipulation of elements easier. The global variable pandoc is bound to the module and should generally not be overwritten for this reason.

Two major functionalities are provided by the module: element creator functions and access to some of pandoc’s main functionalities.

Element creation

Element creator functions like Str, Para, and Pandoc are designed to allow easy creation of new elements that are simple to use and can be read back from the Lua environment. Internally, pandoc uses these functions to create the Lua objects which are passed to element filter functions. This means that elements created via this module will behave exactly as those elements accessible through the filter function parameter.

Exposed pandoc functionality

Some pandoc functions have been made available in Lua:

  • walk_block and walk_inline allow filters to be applied inside specific block or inline elements;
  • read allows filters to parse strings into pandoc documents;
  • pipe runs an external command with input from and output to strings;
  • the pandoc.mediabag module allows access to the “mediabag,” which stores binary content such as images that may be included in the final document;
  • the pandoc.utils module contains various utility functions.

Lua interpreter initialization

Initialization of pandoc’s Lua interpreter can be controlled by placing a file init.lua in pandoc’s data directory. A common use-case would be to load additional modules, or even to alter default modules.

The following snippet is an example of code that might be useful when added to init.lua. The snippet adds all Unicode-aware functions defined in the text module to the default string module, prefixed with the string uc_.

for name, fn in pairs(require 'text') do
  string['uc_' .. name] = fn
end

This makes it possible to apply these functions on strings using colon syntax (mystring:uc_upper()).

Debugging Lua filters

It is possible to use a debugging interface to halt execution and step through a Lua filter line by line as it is run inside Pandoc. This is accomplished using the remote-debugging interface of the package mobdebug. Although mobdebug can be run from the terminal, it is more useful run within the donation-ware Lua editor and IDE, ZeroBrane. ZeroBrane offers a REPL console and UI to step-through and view all variables and state.

If you already have Lua 5.3 installed, you can add mobdebug and its dependency luasocket using luarocks, which should then be available on the path. ZeroBrane also includes both of these in its package, so if you don’t want to install Lua separately, you should add/modify your LUA_PATH and LUA_CPATH to include the correct locations; see detailed instructions here.

Examples

The following filters are presented as examples. A repository of useful Lua filters (which may also serve as good examples) is available at https://github.com/pandoc/lua-filters.

Macro substitution

The following filter converts the string {{helloworld}} into emphasized text “Hello, World”.

return {
  {
    Str = function (elem)
      if elem.text == "{{helloworld}}" then
        return pandoc.Emph {pandoc.Str "Hello, World"}
      else
        return elem
      end
    end,
  }
}

Center images in LaTeX and HTML output

For LaTeX, wrap an image in LaTeX snippets which cause the image to be centered horizontally. In HTML, the image element’s style attribute is used to achieve centering.

-- Filter images with this function if the target format is LaTeX.
if FORMAT:match 'latex' then
  function Image (elem)
    -- Surround all images with image-centering raw LaTeX.
    return {
      pandoc.RawInline('latex', '\\hfill\\break{\\centering'),
      elem,
      pandoc.RawInline('latex', '\\par}')
    }
  end
end

-- Filter images with this function if the target format is HTML
if FORMAT:match 'html' then
  function Image (elem)
    -- Use CSS style to center image
    elem.attributes.style = 'margin:auto; display: block;'
    return elem
  end
end

Setting the date in the metadata

This filter sets the date in the document’s metadata to the current date, if a date isn’t already set:

function Meta(m)
  if m.date == nil then
    m.date = os.date("%B %e, %Y")
    return m
  end
end

Remove spaces before citations

This filter removes all spaces preceding an “author-in-text” citation. In Markdown, author-in-text citations (e.g., @citekey), must be preceded by a space. If these spaces are undesired, they must be removed with a filter.

local function is_space_before_author_in_text(spc, cite)
  return spc and spc.t == 'Space'
    and cite and cite.t == 'Cite'
    -- there must be only a single citation, and it must have
    -- mode 'AuthorInText'
    and #cite.citations == 1
    and cite.citations[1].mode == 'AuthorInText'
end

function Inlines (inlines)
  -- Go from end to start to avoid problems with shifting indices.
  for i = #inlines-1, 1, -1 do
    if is_space_before_author_in_text(inlines[i], inlines[i+1]) then
      inlines:remove(i)
    end
  end
  return inlines
end

Replacing placeholders with their metadata value

Lua filter functions are run in the order

Inlines → Blocks → Meta → Pandoc.

Passing information from a higher level (e.g., metadata) to a lower level (e.g., inlines) is still possible by using two filters living in the same file:

local vars = {}

function get_vars (meta)
  for k, v in pairs(meta) do
    if pandoc.utils.type(v) == 'Inlines' then
      vars["%" .. k .. "%"] = {table.unpack(v)}
    end
  end
end

function replace (el)
  if vars[el.text] then
    return pandoc.Span(vars[el.text])
  else
    return el
  end
end

return {{Meta = get_vars}, {Str = replace}}

If the contents of file occupations.md is

---
name: Samuel Q. Smith
occupation: Professor of Phrenology
---

Name

:   %name%

Occupation

:   %occupation%

then running pandoc --lua-filter=meta-vars.lua occupations.md will output:

<dl>
<dt>Name</dt>
<dd><p><span>Samuel Q. Smith</span></p>
</dd>
<dt>Occupation</dt>
<dd><p><span>Professor of Phrenology</span></p>
</dd>
</dl>

Modifying pandoc’s MANUAL.txt for man pages

This is the filter we use when converting MANUAL.txt to man pages. It converts level-1 headers to uppercase (using walk to transform inline elements inside headers), removes footnotes, and replaces links with regular text.

-- we use pandoc.text to get a UTF-8 aware 'upper' function
local text = pandoc.text

function Header(el)
    if el.level == 1 then
      return el:walk {
        Str = function(el)
            return pandoc.Str(text.upper(el.text))
        end
      }
    end
end

function Link(el)
    return el.content
end

function Note(el)
    return {}
end

Creating a handout from a paper

This filter extracts all the numbered examples, section headers, block quotes, and figures from a document, in addition to any divs with class handout. (Note that only blocks at the “outer level” are included; this ignores blocks inside nested constructs, like list items.)

-- creates a handout from an article, using its headings,
-- blockquotes, numbered examples, figures, and any
-- Divs with class "handout"

function Pandoc(doc)
    local hblocks = {}
    for i,el in pairs(doc.blocks) do
        if (el.t == "Div" and el.classes[1] == "handout") or
           (el.t == "BlockQuote") or
           (el.t == "OrderedList" and el.style == "Example") or
           (el.t == "Para" and #el.c == 1 and el.c[1].t == "Image") or
           (el.t == "Header") then
           table.insert(hblocks, el)
        end
    end
    return pandoc.Pandoc(hblocks, doc.meta)
end

Counting words in a document

This filter counts the words in the body of a document (omitting metadata like titles and abstracts), including words in code. It should be more accurate than wc -w run directly on a Markdown document, since the latter will count markup characters, like the # in front of an ATX header, or tags in HTML documents, as words. To run it, pandoc --lua-filter wordcount.lua myfile.md.

-- counts words in a document

words = 0

wordcount = {
  Str = function(el)
    -- we don't count a word if it's entirely punctuation:
    if el.text:match("%P") then
        words = words + 1
    end
  end,

  Code = function(el)
    _,n = el.text:gsub("%S+","")
    words = words + n
  end,

  CodeBlock = function(el)
    _,n = el.text:gsub("%S+","")
    words = words + n
  end
}

function Pandoc(el)
    -- skip metadata, just count body:
    el.blocks:walk(wordcount)
    print(words .. " words in body")
    os.exit(0)
end

Converting ABC code to music notation

This filter replaces code blocks with class abc with images created by running their contents through abcm2ps and ImageMagick’s convert. (For more on ABC notation, see https://abcnotation.com.)

Images are added to the mediabag. For output to binary formats, pandoc will use images in the mediabag. For textual formats, use --extract-media to specify a directory where the files in the mediabag will be written, or (for HTML only) use --self-contained.

-- Pandoc filter to process code blocks with class "abc" containing
-- ABC notation into images.
--
-- * Assumes that abcm2ps and ImageMagick's convert are in the path.
-- * For textual output formats, use --extract-media=abc-images
-- * For HTML formats, you may alternatively use --self-contained

local filetypes = { html = {"png", "image/png"}
                  , latex = {"pdf", "application/pdf"}
                  }
local filetype = filetypes[FORMAT][1] or "png"
local mimetype = filetypes[FORMAT][2] or "image/png"

local function abc2eps(abc, filetype)
    local eps = pandoc.pipe("abcm2ps", {"-q", "-O", "-", "-"}, abc)
    local final = pandoc.pipe("convert", {"-", filetype .. ":-"}, eps)
    return final
end

function CodeBlock(block)
    if block.classes[1] == "abc" then
        local img = abc2eps(block.text, filetype)
        local fname = pandoc.sha1(img) .. "." .. filetype
        pandoc.mediabag.insert(fname, mimetype, img)
        return pandoc.Para{ pandoc.Image({pandoc.Str("abc tune")}, fname) }
    end
end

Building images with TikZ

This filter converts raw LaTeX TikZ environments into images. It works with both PDF and HTML output. The TikZ code is compiled to an image using pdflatex, and the image is converted from pdf to svg format using pdf2svg, so both of these must be in the system path. Converted images are cached in the working directory and given filenames based on a hash of the source, so that they need not be regenerated each time the document is built. (A more sophisticated version of this might put these in a special cache directory.)

local system = require 'pandoc.system'

local tikz_doc_template = [[
\documentclass{standalone}
\usepackage{xcolor}
\usepackage{tikz}
\begin{document}
\nopagecolor
%s
\end{document}
]]

local function tikz2image(src, filetype, outfile)
  system.with_temporary_directory('tikz2image', function (tmpdir)
    system.with_working_directory(tmpdir, function()
      local f = io.open('tikz.tex', 'w')
      f:write(tikz_doc_template:format(src))
      f:close()
      os.execute('pdflatex tikz.tex')
      if filetype == 'pdf' then
        os.rename('tikz.pdf', outfile)
      else
        os.execute('pdf2svg tikz.pdf ' .. outfile)
      end
    end)
  end)
end

extension_for = {
  html = 'svg',
  html4 = 'svg',
  html5 = 'svg',
  latex = 'pdf',
  beamer = 'pdf' }

local function file_exists(name)
  local f = io.open(name, 'r')
  if f ~= nil then
    io.close(f)
    return true
  else
    return false
  end
end

local function starts_with(start, str)
  return str:sub(1, #start) == start
end


function RawBlock(el)
  if starts_with('\\begin{tikzpicture}', el.text) then
    local filetype = extension_for[FORMAT] or 'svg'
    local fbasename = pandoc.sha1(el.text) .. '.' .. filetype
    local fname = system.get_working_directory() .. '/' .. fbasename
    if not file_exists(fname) then
      tikz2image(el.text, filetype, fname)
    end
    return pandoc.Para({pandoc.Image({}, fbasename)})
  else
   return el
  end
end

Example of use:

pandoc --lua-filter tikz.lua -s -o cycle.html <<EOF
Here is a diagram of the cycle:

\begin{tikzpicture}

\def \n {5}
\def \radius {3cm}
\def \margin {8} % margin in angles, depends on the radius

\foreach \s in {1,...,\n}
{
  \node[draw, circle] at ({360/\n * (\s - 1)}:\radius) {$\s$};
  \draw[->, >=latex] ({360/\n * (\s - 1)+\margin}:\radius)
    arc ({360/\n * (\s - 1)+\margin}:{360/\n * (\s)-\margin}:\radius);
}
\end{tikzpicture}
EOF

Lua type reference

This section describes the types of objects available to Lua filters. See the pandoc module for functions to create these objects.

Shared Properties

clone

clone ()

All instances of the types listed here, with the exception of read-only objects, can be cloned via the clone() method.

Usage:

local emph = pandoc.Emph {pandoc.Str 'important'}
local cloned_emph = emph:clone()  -- note the colon

Pandoc

Pandoc document

Values of this type can be created with the pandoc.Pandoc constructor. Pandoc values are equal in Lua if and only if they are equal in Haskell.

blocks
document content (Blocks)
meta
document meta information (Meta object)

walk

walk(self, lua_filter)

Applies a Lua filter to the Pandoc element. Just as for full-document filters, the order in which elements are traversed can be controlled by setting the traverse field of the filter; see the section on traversal order.

Parameters:

self
the element (Pandoc)
lua_filter
map of filter functions (table)

Result:

Usage:

-- returns `pandoc.Pandoc{pandoc.Para{pandoc.Str 'Bye'}}`
return pandoc.Pandoc{pandoc.Para('Hi')}:walk {
  Str = function (_) return 'Bye' end,
}

Meta

Meta information on a document; string-indexed collection of MetaValues.

Values of this type can be created with the pandoc.Meta constructor. Meta values are equal in Lua if and only if they are equal in Haskell.

MetaValue

Document meta information items. This is not a separate type, but describes a set of types that can be used in places were a MetaValue is expected. The types correspond to the following Haskell type constructors:

  • boolean → MetaBool
  • string or number → MetaString
  • Inlines → MetaInlines
  • Blocks → MetaBlocks
  • List/integer indexed table → MetaList
  • string-indexed table → MetaMap

The corresponding constructors pandoc.MetaBool, pandoc.MetaString, pandoc.MetaInlines, pandoc.MetaBlocks, pandoc.MetaList, and pandoc.MetaMap can be used to ensure that a value is treated in the intended way. E.g., an empty table is normally treated as a MetaMap, but can be made into an empty MetaList by calling pandoc.MetaList{}. However, the same can be accomplished by using the generic functions like pandoc.List, pandoc.Inlines, or pandoc.Blocks.

Use the function pandoc.utils.type to get the type of a metadata value.

Block

Block values are equal in Lua if and only if they are equal in Haskell.

Common methods

walk

walk(self, lua_filter)

Applies a Lua filter to the block element. Just as for full-document filters, the order in which elements are traversed can be controlled by setting the traverse field of the filter; see the section on traversal order.

Note that the filter is applied to the subtree, but not to the self block element. The rationale is that otherwise the element could be deleted by the filter, or replaced with multiple block elements, which might lead to possibly unexpected results.

Parameters:

self
the element (Block)
lua_filter
map of filter functions (table)

Result:

Usage:

-- returns `pandoc.Para{pandoc.Str 'Bye'}`
return pandoc.Para('Hi'):walk {
  Str = function (_) return 'Bye' end,
}

BlockQuote

A block quote element.

Values of this type can be created with the pandoc.BlockQuote constructor.

Fields:

content
block content (Blocks)
tag, t
the literal BlockQuote (string)

BulletList

A bullet list.

Values of this type can be created with the pandoc.BulletList constructor.

Fields:

content
list items (List of items, i.e., List of Blocks)
tag, t
the literal BulletList (string)

CodeBlock

Block of code.

Values of this type can be created with the pandoc.CodeBlock constructor.

Fields:

text
code string (string)
attr
element attributes (Attr)
identifier
alias for attr.identifier (string)
classes
alias for attr.classes (List of strings)
attributes
alias for attr.attributes (Attributes)
tag, t
the literal CodeBlock (string)

DefinitionList

Definition list, containing terms and their explanation.

Values of this type can be created with the pandoc.DefinitionList constructor.

Fields:

content
list of items
tag, t
the literal DefinitionList (string)

Div

Generic block container with attributes.

Values of this type can be created with the pandoc.Div constructor.

Fields:

content
block content (Blocks)
attr
element attributes (Attr)
identifier
alias for attr.identifier (string)
classes
alias for attr.classes (List of strings)
attributes
alias for attr.attributes (Attributes)
tag, t
the literal Div (string)

Header

Creates a header element.

Values of this type can be created with the pandoc.Header constructor.

Fields:

level
header level (integer)
content
inline content (Inlines)
attr
element attributes (Attr)
identifier
alias for attr.identifier (string)
classes
alias for attr.classes (List of strings)
attributes
alias for attr.attributes (Attributes)
tag, t
the literal Header (string)

HorizontalRule

A horizontal rule.

Values of this type can be created with the pandoc.HorizontalRule constructor.

Fields:

tag, t
the literal HorizontalRule (string)

LineBlock

A line block, i.e. a list of lines, each separated from the next by a newline.

Values of this type can be created with the pandoc.LineBlock constructor.

Fields:

content
inline content (List of lines, i.e. List of Inlines)
tag, t
the literal LineBlock (string)

Null

A null element; this element never produces any output in the target format.

Values of this type can be created with the pandoc.Null constructor.

tag, t
the literal Null (string)

OrderedList

An ordered list.

Values of this type can be created with the pandoc.OrderedList constructor.

Fields:

content
list items (List of items, i.e., List of Blocks)
listAttributes
list parameters (ListAttributes)
start
alias for listAttributes.start (integer)
style
alias for listAttributes.style (string)
delimiter
alias for listAttributes.delimiter (string)
tag, t
the literal OrderedList (string)

Para

A paragraph.

Values of this type can be created with the pandoc.Para constructor.

Fields:

content
inline content (Inlines)
tag, t
the literal Para (string)

Plain

Plain text, not a paragraph.

Values of this type can be created with the pandoc.Plain constructor.

Fields:

content
inline content (Inlines)
tag, t
the literal Plain (string)

RawBlock

Raw content of a specified format.

Values of this type can be created with the pandoc.RawBlock constructor.

Fields:

format
format of content (string)
text
raw content (string)
tag, t
the literal RawBlock (string)

Table

A table.

Values of this type can be created with the pandoc.Table constructor.

Fields:

attr
table attributes (Attr)
caption
table caption (Caption)
colspecs
column specifications, i.e., alignments and widths (List of ColSpecs)
head
table head (TableHead)
bodies
table bodies (List of TableBodys)
foot
table foot (TableFoot)
identifier
alias for attr.identifier (string)
classes
alias for attr.classes (List of strings)
attributes
alias for attr.attributes (Attributes)
tag, t
the literal Table (string)

A table cell is a list of blocks.

Alignment is a string value indicating the horizontal alignment of a table column. AlignLeft, AlignRight, and AlignCenter leads cell content to be left-aligned, right-aligned, and centered, respectively. The default alignment is AlignDefault (often equivalent to centered).

Blocks

List of Block elements, with the same methods as a generic List. It is usually not necessary to create values of this type in user scripts, as pandoc can convert other types into Blocks wherever a value of this type is expected:

  • a list of Block (or Block-like) values is used directly;
  • a single Inlines value is wrapped into a Plain element;
  • string values are turned into an Inlines value by splitting the string into words (see Inlines), and then wrapping the result into a Plain singleton.

Methods

Lists of type Blocks share all methods available in generic lists, see the pandoc.List module.

Additionally, the following methods are available on Blocks values:

walk

walk(self, lua_filter)

Applies a Lua filter to the Blocks list. Just as for full-document filters, the order in which elements are traversed can be controlled by setting the traverse field of the filter; see the section on traversal order.

Parameters:

self
the list (Blocks)
lua_filter
map of filter functions (table)

Result:

Usage:

-- returns `pandoc.Blocks{pandoc.Para('Salve!')}`
return pandoc.Blocks{pandoc.Plain('Salve!)}:walk {
  Plain = function (p) return pandoc.Para(p.content) end,
}

Inline

Inline values are equal in Lua if and only if they are equal in Haskell.

Common methods

walk

walk(self, lua_filter)

Applies a Lua filter to the Inline element. Just as for full-document filters, the order in which elements are traversed can be controlled by setting the traverse field of the filter; see the section on traversal order.

Note that the filter is applied to the subtree, but not to the self inline element. The rationale is that otherwise the element could be deleted by the filter, or replaced with multiple inline elements, which might lead to possibly unexpected results.

Parameters:

self
the element (Inline)
lua_filter
map of filter functions (table)

Result:

  • filtered inline element (Inline)

Usage:

-- returns `pandoc.SmallCaps('SPQR)`
return pandoc.SmallCaps('spqr'):walk {
  Str = function (s) return string.upper(s.text) end,
}

Cite

Citation.

Values of this type can be created with the pandoc.Cite constructor.

Fields:

content
(Inlines)
citations
citation entries (List of Citations)
tag, t
the literal Cite (string)

Code

Inline code

Values of this type can be created with the pandoc.Code constructor.

Fields:

text
code string (string)
attr
attributes (Attr)
identifier
alias for attr.identifier (string)
classes
alias for attr.classes (List of strings)
attributes
alias for attr.attributes (Attributes)
tag, t
the literal Code (string)

Emph

Emphasized text

Values of this type can be created with the pandoc.Emph constructor.

Fields:

content
inline content (Inlines)
tag, t
the literal Emph (string)

Image

Image: alt text (list of inlines), target

Values of this type can be created with the pandoc.Image constructor.

Fields:

caption
text used to describe the image (Inlines)
src
path to the image file (string)
title
brief image description (string)
attr
attributes (Attr)
identifier
alias for attr.identifier (string)
classes
alias for attr.classes (List of strings)
attributes
alias for attr.attributes (Attributes)
tag, t
the literal Image (string)

LineBreak

Hard line break

Values of this type can be created with the pandoc.LineBreak constructor.

Fields:

tag, t
the literal LineBreak (string)

Math

TeX math (literal)

Values of this type can be created with the pandoc.Math constructor.

Fields:

mathtype
specifier determining whether the math content should be shown inline (InlineMath) or on a separate line (DisplayMath) (string)
text
math content (string)
tag, t
the literal Math (string)

Note

Footnote or endnote

Values of this type can be created with the pandoc.Note constructor.

Fields:

content
(Blocks)
tag, t
the literal Note (string)

Quoted

Quoted text

Values of this type can be created with the pandoc.Quoted constructor.

Fields:

quotetype
type of quotes to be used; one of SingleQuote or DoubleQuote (string)
content
quoted text (Inlines)
tag, t
the literal Quoted (string)

RawInline

Raw inline

Values of this type can be created with the pandoc.RawInline constructor.

Fields:

format
the format of the content (string)
text
raw content (string)
tag, t
the literal RawInline (string)

SmallCaps

Small caps text

Values of this type can be created with the pandoc.SmallCaps constructor.

Fields:

content
(Inlines)
tag, t
the literal SmallCaps (string)

SoftBreak

Soft line break

Values of this type can be created with the pandoc.SoftBreak constructor.

Fields:

tag, t
the literal SoftBreak (string)

Space

Inter-word space

Values of this type can be created with the pandoc.Space constructor.

Fields:

tag, t
the literal Space (string)

Span

Generic inline container with attributes

Values of this type can be created with the pandoc.Span constructor.

Fields:

attr
attributes (Attr)
content
wrapped content (Inlines)
identifier
alias for attr.identifier (string)
classes
alias for attr.classes (List of strings)
attributes
alias for attr.attributes (Attributes)
tag, t
the literal Span (string)

Str

Text

Values of this type can be created with the pandoc.Str constructor.

Fields:

text
content (string)
tag, t
the literal Str (string)

Strikeout

Strikeout text

Values of this type can be created with the pandoc.Strikeout constructor.

Fields:

content
inline content (Inlines)
tag, t
the literal Strikeout (string)

Strong

Strongly emphasized text

Values of this type can be created with the pandoc.Strong constructor.

Fields:

content
inline content (Inlines)
tag, t
the literal Strong (string)

Subscript

Subscripted text

Values of this type can be created with the pandoc.Subscript constructor.

Fields:

content
inline content (Inlines)
tag, t
the literal Subscript (string)

Superscript

Superscripted text

Values of this type can be created with the pandoc.Superscript constructor.

Fields:

content
inline content (Inlines)
tag, t
the literal Superscript (string)

Underline

Underlined text

Values of this type can be created with the pandoc.Underline constructor.

Fields:

content
inline content (Inlines)
tag, t
the literal Underline (string)

Inlines

List of Inline elements, with the same methods as a generic List. It is usually not necessary to create values of this type in user scripts, as pandoc can convert other types into Blocks wherever a value of this type is expected:

  • lists of Inline (or Inline-like) values are used directly;
  • single Inline values are converted into a list containing just that element;
  • String values are split into words, converting line breaks into SoftBreak elements, and other whitespace characters into Spaces.

Methods

Lists of type Inlines share all methods available in generic lists, see the pandoc.List module.

Additionally, the following methods are available on Inlines values:

walk

walk(self, lua_filter)

Applies a Lua filter to the Inlines list. Just as for full-document filters, the order in which elements are handled are are Inline → Inlines → Block → Blocks. The filter is applied to all list items and to the list itself.

Parameters:

self
the list (Inlines)
lua_filter
map of filter functions (table)

Result:

Usage:

-- returns `pandoc.Inlines{pandoc.SmallCaps('SPQR')}`
return pandoc.Inlines{pandoc.Emph('spqr')}:walk {
  Str = function (s) return string.upper(s.text) end,
  Emph = function (e) return pandoc.SmallCaps(e.content) end,
}

Element components

Attr

A set of element attributes. Values of this type can be created with the pandoc.Attr constructor. For convenience, it is usually not necessary to construct the value directly if it is part of an element, and it is sufficient to pass an HTML-like table. E.g., to create a span with identifier “text” and classes “a” and “b”, one can write:

local span = pandoc.Span('text', {id = 'text', class = 'a b'})

This also works when using the attr setter:

local span = pandoc.Span 'text'
span.attr = {id = 'text', class = 'a b', other_attribute = '1'}

Attr values are equal in Lua if and only if they are equal in Haskell.

Fields:

identifier
element identifier (string)
classes
element classes (List of strings)
attributes
collection of key/value pairs (Attributes)

Attributes

List of key/value pairs. Values can be accessed by using keys as indices to the list table.

Attributes values are equal in Lua if and only if they are equal in Haskell.

Caption

The caption of a table, with an optional short caption.

Fields:

long
long caption (Blocks)
short
short caption (Inlines)

Cell

A table cell.

Fields:

attr
cell attributes
alignment
individual cell alignment (Alignment).
contents
cell contents (Blocks).
col_span
number of columns spanned by the cell; the width of the cell in columns (integer).
row_span
number of rows spanned by the cell; the height of the cell in rows (integer).
identifier
alias for attr.identifier (string)
classes
alias for attr.classes (List of strings)
attributes
alias for attr.attributes (Attributes)

Citation

Single citation entry

Values of this type can be created with the pandoc.Citation constructor.

Citation values are equal in Lua if and only if they are equal in Haskell.

Fields:

id
citation identifier, e.g., a bibtex key (string)
mode
citation mode, one of AuthorInText, SuppressAuthor, or NormalCitation (string)
prefix
citation prefix (Inlines)
suffix
citation suffix (Inlines)
note_num
note number (integer)
hash
hash (integer)

ColSpec

Column alignment and width specification for a single table column.

This is a pair, i.e., a plain table, with the following components:

  1. cell alignment (Alignment).
  2. table column width, as a fraction of the page width (number).

ListAttributes

List attributes

Values of this type can be created with the pandoc.ListAttributes constructor.

Fields:

start
number of the first list item (integer)
style
style used for list numbers; possible values are DefaultStyle, Example, Decimal, LowerRoman, UpperRoman, LowerAlpha, and UpperAlpha (string)
delimiter
delimiter of list numbers; one of DefaultDelim, Period, OneParen, and TwoParens (string)

Row

A table row.

Fields:

attr
element attributes (Attr)
cells
list of table cells (List of Cells)

TableBody

A body of a table, with an intermediate head and the specified number of row header columns.

Fields:

attr
table body attributes (Attr)
body
table body rows (List of Rows)
head
intermediate head (List of Rows)
row_head_columns
number of columns taken up by the row head of each row of a TableBody. The row body takes up the remaining columns.

TableFoot

The foot of a table.

Fields:

attr
element attributes (Attr)
rows
list of rows (List of Rows)
identifier
alias for attr.identifier (string)
classes
alias for attr.classes (List of strings)
attributes
alias for attr.attributes (Attributes)

TableHead

The head of a table.

Fields:

attr
element attributes (Attr)
rows
list of rows (List of Rows)
identifier
alias for attr.identifier (string)
classes
alias for attr.classes (List of strings)
attributes
alias for attr.attributes (Attributes)

ReaderOptions

Pandoc reader options

Fields:

abbreviations
set of known abbreviations (set of strings)
columns
number of columns in terminal (integer)
default_image_extension
default extension for images (string)
extensions
string representation of the syntax extensions bit field (sequence of strings)
indented_code_classes
default classes for indented code blocks (list of strings)
standalone
whether the input was a standalone document with header (boolean)
strip_comments
HTML comments are stripped instead of parsed as raw HTML (boolean)
tab_stop
width (i.e. equivalent number of spaces) of tab stops (integer)
track_changes
track changes setting for docx; one of accept-changes, reject-changes, and all-changes (string)

WriterOptions

Pandoc writer options

Fields:

cite_method
How to print cites – one of ‘citeproc’, ‘natbib’, or ‘biblatex’ (string)
columns
Characters in a line (for text wrapping) (integer)
dpi
DPI for pixel to/from inch/cm conversions (integer)
email_obfuscation
How to obfuscate emails – one of ‘none’, ‘references’, or ‘javascript’ (string)
epub_chapter_level
Header level for chapters, i.e., how the document is split into separate files (integer)
epub_fonts
Paths to fonts to embed (sequence of strings)
epub_metadata
Metadata to include in EPUB (string|nil)
epub_subdirectory
Subdir for epub in OCF (string)
extensions
Markdown extensions that can be used (sequence of strings)
highlight_style
Style to use for highlighting; see the output of pandoc --print-highlight-style=... for an example structure. The value nil means that no highlighting is used. (table|nil)
html_math_method
How to print math in HTML; one ‘plain’, ‘gladtex’, ‘webtex’, ‘mathml’, ‘mathjax’, or a table with keys method and url. (string|table)
html_q_tags
Use <q> tags for quotes in HTML (boolean)
identifier_prefix
Prefix for section & note ids in HTML and for footnote marks in markdown (string)
incremental
True if lists should be incremental (boolean)
listings
Use listings package for code (boolean)
number_offset
Starting number for section, subsection, … (sequence of integers)
number_sections
Number sections in LaTeX (boolean)
prefer_ascii
Prefer ASCII representations of characters when possible (boolean)
reference_doc
Path to reference document if specified (string|nil)
reference_links
Use reference links in writing markdown, rst (boolean)
reference_location
Location of footnotes and references for writing markdown; one of ‘end-of-block’, ‘end-of-section’, ‘end-of-document’. The common prefix may be omitted when setting this value. (string)
section_divs
Put sections in div tags in HTML (boolean)
setext_headers
Use setext headers for levels 1-2 in markdown (boolean)
slide_level
Force header level of slides (integer|nil)
tab_stop
Tabstop for conversion btw spaces and tabs (integer)
table_of_contents
Include table of contents (boolean)
template
Template to use (Template|nil)
toc_depth
Number of levels to include in TOC (integer)
top_level_division
Type of top-level divisions; one of ‘top-level-part’, ‘top-level-chapter’, ‘top-level-section’, or ‘top-level-default’. The prefix top-level may be omitted when setting this value. (string)
variables
Variables to set in template; string-indexed table (table)
wrap_text
Option for wrapping text; one of ‘wrap-auto’, ‘wrap-none’, or ‘wrap-preserve’. The wrap- prefix may be omitted when setting this value. (string)

CommonState

The state used by pandoc to collect information and make it available to readers and writers.

Fields:

input_files
List of input files from command line (List of strings)
output_file
Output file from command line (string or nil)
log
A list of log messages in reverse order (List of LogMessages)
request_headers
Headers to add for HTTP requests; table with header names as keys and header contents as value (table)
resource_path
Path to search for resources like included images (List of strings)
source_url
Absolute URL or directory of first source file (string or nil)
user_data_dir
Directory to search for data files (string or nil)
trace
Whether tracing messages are issued (boolean)
verbosity
Verbosity level; one of INFO, WARNING, ERROR (string)

Doc

Reflowable plain-text document. A Doc value can be rendered and reflown to fit a given column width.

The pandoc.layout module can be used to create and modify Doc values. All functions in that module that take a Doc value as their first argument are also available as Doc methods. E.g., (pandoc.layout.literal 'text'):render().

If a string is passed to a function expecting a Doc, then the string is treated as a literal value. I.e., the following two lines are equivalent:

test = pandoc.layout.quotes(pandoc.layout.literal 'this')
test = pandoc.layout.quotes('this')

List

A list is any Lua table with integer indices. Indices start at one, so if alist = {'value'} then alist[1] == 'value'.

Lists, when part of an element, or when generated during marshaling, are made instances of the pandoc.List type for convenience. The pandoc.List type is defined in the pandoc.List module. See there for available methods.

Values of this type can be created with the pandoc.List constructor, turning a normal Lua table into a List.

LogMessage

A pandoc log message. Objects have no fields, but can be converted to a string via tostring.

SimpleTable

A simple table is a table structure which resembles the old (pre pandoc 2.10) Table type. Bi-directional conversion from and to Tables is possible with the pandoc.utils.to_simple_table and pandoc.utils.from_simple_table function, respectively. Instances of this type can also be created directly with the pandoc.SimpleTable constructor.

Fields:

caption
Inlines
aligns
column alignments (List of Alignments)
widths
column widths; a (List of numbers)
headers
table header row (List of simple cells, i.e., List of Blocks)
rows
table rows (List of rows, where a row is a list of simple cells, i.e., List of Blocks)

Template

Opaque type holding a compiled template.

Version

A version object. This represents a software version like “2.7.3”. The object behaves like a numerically indexed table, i.e., if version represents the version 2.7.3, then

version[1] == 2
version[2] == 7
version[3] == 3
#version == 3   -- length

Comparisons are performed element-wise, i.e.

Version '1.12' > Version '1.9'

Values of this type can be created with the pandoc.types.Version constructor.

must_be_at_least

must_be_at_least(actual, expected [, error_message])

Raise an error message if the actual version is older than the expected version; does nothing if actual is equal to or newer than the expected version.

Parameters:

actual
actual version specifier (Version)
expected
minimum expected version (Version)
error_message
optional error message template. The string is used as format string, with the expected and actual versions as arguments. Defaults to "expected version %s or newer, got %s".

Usage:

PANDOC_VERSION:must_be_at_least '2.7.3'
PANDOC_API_VERSION:must_be_at_least(
  '1.17.4',
  'pandoc-types is too old: expected version %s, got %s'
)

Module text

UTF-8 aware text manipulation functions, implemented in Haskell. The module is made available as part of the pandoc module via pandoc.text. The text module can also be loaded explicitly:

-- uppercase all regular text in a document:
text = require 'text'
function Str (s)
  s.text = text.upper(s.text)
  return s
end

lower

lower (s)

Returns a copy of a UTF-8 string, converted to lowercase.

upper

upper (s)

Returns a copy of a UTF-8 string, converted to uppercase.

reverse

reverse (s)

Returns a copy of a UTF-8 string, with characters reversed.

len

len (s)

Returns the length of a UTF-8 string.

sub

sub (s)

Returns a substring of a UTF-8 string, using Lua’s string indexing rules.

Module pandoc

Lua functions for pandoc scripts; includes constructors for document tree elements, functions to parse text in a given format, and functions to filter and modify a subtree.

Pandoc

Pandoc (blocks[, meta])

A complete pandoc document

Parameters:

blocks
document content
meta
document meta data

Returns: Pandoc object

Meta

Meta (table)

Create a new Meta object.

Parameters:

table
table containing document meta information

Returns: Meta object

MetaValue

MetaBlocks (blocks)

Creates a value to be used as a MetaBlocks value in meta data; creates a copy of the input list via pandoc.Blocks, discarding all non-list keys.

Parameters:

blocks
blocks

Returns: Blocks

MetaInlines (inlines)

Creates a value to be used as a MetaInlines value in meta data; creates a copy of the input list via pandoc.Inlines, discarding all non-list keys.

Parameters:

inlines
inlines

Returns: Inlines

MetaList (meta_values)

Creates a value to be used as a MetaList in meta data; creates a copy of the input list via pandoc.List, discarding all non-list keys.

Parameters:

meta_values
list of meta values

Returns: List

MetaMap (key_value_map)

Creates a value to be used as a MetaMap in meta data; creates a copy of the input table, keeping only pairs with string keys and discards all other keys.

Parameters:

key_value_map
a string-indexed map of meta values

Returns: table

MetaString (str)

Creates a value to be used as a MetaString in meta data; this is the identity function for boolean values and exists only for completeness.

Parameters:

str
string value

Returns: string

MetaBool (bool)

Creates a value to be used as MetaBool in meta data; this is the identity function for boolean values and exists only for completeness.

Parameters:

bool
boolean value

Returns: boolean

Block

BlockQuote (content)

Creates a block quote element

Parameters:

content
block content

Returns: BlockQuote object

BulletList (items)

Creates a bullet list.

Parameters:

items
list items

Returns: BulletList object

CodeBlock (text[, attr])

Creates a code block element

Parameters:

text
code string
attr
element attributes

Returns: CodeBlock object

DefinitionList (content)

Creates a definition list, containing terms and their explanation.

Parameters:

content
list of items

Returns: DefinitionList object

Div (content[, attr])

Creates a div element

Parameters:

content
block content
attr
element attributes

Returns: Div object

Header (level, content[, attr])

Creates a header element.

Parameters:

level
header level
content
inline content
attr
element attributes

Returns: Header object

HorizontalRule ()

Creates a horizontal rule.

Returns: HorizontalRule object

LineBlock (content)

Creates a line block element.

Parameters:

content
inline content

Returns: LineBlock object

Null ()

Creates a null element.

Returns: Null object

OrderedList (items[, listAttributes])

Creates an ordered list.

Parameters:

items
list items
listAttributes
list parameters

Returns: OrderedList object

Para (content)

Creates a para element.

Parameters:

content
inline content

Returns: Para object

Plain (content)

Creates a plain element.

Parameters:

content
inline content

Returns: Plain object

RawBlock (format, text)

Creates a raw content block of the specified format.

Parameters:

format
format of content
text
string content

Returns: RawBlock object

Table (caption, colspecs, head, bodies, foot[, attr])

Creates a table element.

Parameters:

caption
table caption
colspecs
column alignments and widths (list of ColSpecs)
head
table head
bodies
table bodies
foot
table foot
attr
element attributes

Returns: Table object

Blocks

Blocks (block_like_elements)

Creates a Blocks list.

Parameters:

block_like_elements
List where each element can be treated as a Block value, or a single such value.

Returns: Blocks

Inline

Cite (content, citations)

Creates a Cite inline element

Parameters:

content
List of inlines
citations
List of citations

Returns: Cite object

Code (text[, attr])

Creates a Code inline element

Parameters:

text
code string
attr
additional attributes

Returns: Code object

Emph (content)

Creates an inline element representing emphasized text.

Parameters:

content
inline content

Returns: Emph object

Image (caption, src[, title[, attr]])

Creates a Image inline element

Parameters:

caption
text used to describe the image
src
path to the image file
title
brief image description
attr
additional attributes

Returns: Image object

LineBreak ()

Create a LineBreak inline element

Returns: LineBreak object

Math (mathtype, text)

Creates a Math element, either inline or displayed.

Parameters:

mathtype
rendering specifier
text
Math content

Returns: Math object

DisplayMath (text)

Creates a math element of type “DisplayMath” (DEPRECATED).

Parameters:

text
Math content

Returns: Math object

InlineMath (text)

Creates a math element of type “InlineMath” (DEPRECATED).

Parameters:

text
Math content

Returns: Math object

Note (content)

Creates a Note inline element

Parameters:

content
footnote block content

Returns: Note object

Quoted (quotetype, content)

Creates a Quoted inline element given the quote type and quoted content.

Parameters:

quotetype
type of quotes to be used
content
inline content

Returns: Quoted object

SingleQuoted (content)

Creates a single-quoted inline element (DEPRECATED).

Parameters:

content
inline content

Returns: Quoted

DoubleQuoted (content)

Creates a single-quoted inline element (DEPRECATED).

Parameters:

content
inline content

Returns: Quoted

RawInline (format, text)

Creates a raw inline element

Parameters:

format
format of the contents
text
string content

Returns: RawInline object

SmallCaps (content)

Creates text rendered in small caps

Parameters:

content
inline content

Returns: SmallCaps object

SoftBreak ()

Creates a SoftBreak inline element.

Returns: SoftBreak object

Space ()

Create a Space inline element

Returns: Space object

Span (content[, attr])

Creates a Span inline element

Parameters:

content
inline content
attr
additional attributes

Returns: Span object

Str (text)

Creates a Str inline element

Parameters:

text
content

Returns: Str object

Strikeout (content)

Creates text which is struck out.

Parameters:

content
inline content

Returns: Strikeout object

Strong (content)

Creates a Strong element, whose text is usually displayed in a bold font.

Parameters:

content
inline content

Returns: Strong object

Subscript (content)

Creates a Subscript inline element

Parameters:

content
inline content

Returns: Subscript object

Superscript (content)

Creates a Superscript inline element

Parameters:

content
inline content

Returns: Superscript object

Underline (content)

Creates an Underline inline element

Parameters:

content
inline content

Returns: Underline object

Inlines

Inlines (inline_like_elements)

Converts its argument into an Inlines list:

  • copies a list of Inline elements into a fresh list; any string s within the list is treated as pandoc.Str(s);
  • turns a single Inline into a singleton list;
  • splits a string into Str-wrapped words, treating interword spaces as Spaces or SoftBreaks.

Parameters:

inline_like_elements
List where each element can be treated as an Inline values, or just a single such value.

Returns: Inlines list

Element components

Attr ([identifier[, classes[, attributes]]])

Create a new set of attributes (Attr).

Parameters:

identifier
element identifier
classes
element classes
attributes
table containing string keys and values

Returns: Attr object

Cell (blocks[, align[, rowspan[, colspan[, attr]]]])

Create a new table cell.

Parameters:

blocks
cell contents (Blocks)
align
text alignment; defaults to AlignDefault (Alignment)
rowspan
number of rows occupied by the cell; defaults to 1 (integer)
colspan
number of columns spanned by the cell; defaults to 1 (integer)
attr
cell attributes (Attr)

Returns:

Citation (id, mode[, prefix[, suffix[, note_num[, hash]]]])

Creates a single citation.

Parameters:

id
citation identifier (like a bibtex key)
mode
citation mode
prefix
citation prefix
suffix
citation suffix
note_num
note number
hash
hash number

Returns: Citation object

ListAttributes ([start[, style[, delimiter]]])

Creates a set of list attributes.

Parameters:

start
number of the first list item
style
style used for list numbering
delimiter
delimiter of list numbers

Returns: ListAttributes object

Row ([cells[, attr]])

Creates a table row.

Parameters:

cells
list of table cells in this row
attr
row attributes

TableFoot ([rows[, attr]])

Creates a table foot.

Parameters:

rows
list of table rows
attr
table foot attributes

TableHead ([rows[, attr]])

Creates a table head.

Parameters:

rows
list of table rows
attr
table head attributes

Legacy types

SimpleTable (caption, aligns, widths, headers, rows)

Creates a simple table resembling the old (pre pandoc 2.10) table type.

Parameters:

caption
Inlines
aligns
column alignments (List of Alignments)
widths
column widths; a (List of numbers)
headers
table header row (List of Blocks)
rows
table rows (List of rows, where a row is a list of Blocks)

Returns: SimpleTable object

Usage:

local caption = "Overview"
local aligns = {pandoc.AlignDefault, pandoc.AlignDefault}
local widths = {0, 0} -- let pandoc determine col widths
local headers = {{pandoc.Plain({pandoc.Str "Language"})},
                 {pandoc.Plain({pandoc.Str "Typing"})}}
local rows = {
  {{pandoc.Plain "Haskell"}, {pandoc.Plain "static"}},
  {{pandoc.Plain "Lua"}, {pandoc.Plain "Dynamic"}},
}
simple_table = pandoc.SimpleTable(
  caption,
  aligns,
  widths,
  headers,
  rows
)

Constants

AuthorInText

Author name is mentioned in the text.

See also: Citation

SuppressAuthor

Author name is suppressed.

See also: Citation

NormalCitation

Default citation style is used.

See also: Citation

AlignLeft

Table cells aligned left.

See also: Table

AlignRight

Table cells right-aligned.

See also: Table

AlignCenter

Table cell content is centered.

See also: Table

AlignDefault

Table cells are alignment is unaltered.

See also: Table

DefaultDelim

Default list number delimiters are used.

See also: ListAttributes

Period

List numbers are delimited by a period.

See also: ListAttributes

OneParen

List numbers are delimited by a single parenthesis.

See also: ListAttributes

TwoParens

List numbers are delimited by a double parentheses.

See also: ListAttributes

DefaultStyle

List are numbered in the default style

See also: ListAttributes

Example

List items are numbered as examples.

See also: ListAttributes

Decimal

List are numbered using decimal integers.

See also: ListAttributes

LowerRoman

List are numbered using lower-case roman numerals.

See also: ListAttributes

UpperRoman

List are numbered using upper-case roman numerals

See also: ListAttributes

LowerAlpha

List are numbered using lower-case alphabetic characters.

See also: ListAttributes

UpperAlpha

List are numbered using upper-case alphabetic characters.

See also: ListAttributes

sha1

Alias for pandoc.utils.sha1 (DEPRECATED, use pandoc.utils.sha1 instead).

Other constructors

ReaderOptions (opts)

Creates a new ReaderOptions value.

Parameters

opts
Either a table with a subset of the properties of a ReaderOptions object, or another ReaderOptions object. Uses the defaults specified in the manual for all properties that are not explicitly specified. Throws an error if a table contains properties which are not present in a ReaderOptions object. (ReaderOptions|table)

Returns: new ReaderOptions object

Usage:

-- copy of the reader options that were defined on the command line.
local cli_opts = pandoc.ReaderOptions(PANDOC_READER_OPTIONS)

-- default reader options, but columns set to 66.
local short_colums_opts = pandoc.ReaderOptions {columns = 66}

WriterOptions (opts)

Creates a new WriterOptions value.

Parameters

opts
Either a table with a subset of the properties of a WriterOptions object, or another WriterOptions object. Uses the defaults specified in the manual for all properties that are not explicitly specified. Throws an error if a table contains properties which are not present in a WriterOptions object. (WriterOptions|table)

Returns: new WriterOptions object

Usage:

-- copy of the writer options that were defined on the command line.
local cli_opts = pandoc.WriterOptions(PANDOC_WRITER_OPTIONS)

-- default writer options, but DPI set to 300.
local short_colums_opts = pandoc.WriterOptions {dpi = 300}

Helper functions

pipe (command, args, input)

Runs command with arguments, passing it some input, and returns the output.

Parameters:

command
program to run; the executable will be resolved using default system methods (string).
args
list of arguments to pass to the program (list of strings).
input
data which is piped into the program via stdin (string).

Returns:

  • Output of command, i.e. data printed to stdout (string)

Raises:

  • A table containing the keys command, error_code, and output is thrown if the command exits with a non-zero error code.

Usage:

local output = pandoc.pipe("sed", {"-e","s/a/b/"}, "abc")

walk_block (element, filter)

Apply a filter inside a block element, walking its contents.

Parameters:

element
the block element
filter
a Lua filter (table of functions) to be applied within the block element

Returns: the transformed block element

walk_inline (element, filter)

Apply a filter inside an inline element, walking its contents.

Parameters:

element
the inline element
filter
a Lua filter (table of functions) to be applied within the inline element

Returns: the transformed inline element

read (markup[, format[, reader_options]])

Parse the given string into a Pandoc document.

The parser is run in the same environment that was used to read the main input files; it has full access to the file-system and the mediabag. This means that if the document specifies files to be included, as is possible in formats like LaTeX, reStructuredText, and Org, then these will be included in the resulting document. Any media elements are added to those retrieved from the other parsed input files.

Parameters:

markup
the markup to be parsed (string|Sources)
format
format specification, defaults to "markdown" (string)
reader_options
options passed to the reader; may be a ReaderOptions object or a table with a subset of the keys and values of a ReaderOptions object; defaults to the default values documented in the manual. (ReaderOptions|table)

Returns: pandoc document (Pandoc)

Usage:

local org_markup = "/emphasis/"  -- Input to be read
local document = pandoc.read(org_markup, "org")
-- Get the first block of the document
local block = document.blocks[1]
-- The inline element in that block is an `Emph`
assert(block.content[1].t == "Emph")

write (doc[, format[, writer_options]])

Converts a document to the given target format.

Parameters:

doc
document to convert (Pandoc)
format
format specification, defaults to 'html' (string)
writer_options
options passed to the writer; may be a WriterOptions object or a table with a subset of the keys and values of a WriterOptions object; defaults to the default values documented in the manual. (WriterOptions|table)

Returns:

  • converted document (string)

Usage:

local doc = pandoc.Pandoc(
  {pandoc.Para {pandoc.Strong 'Tea'}}
)
local html = pandoc.write(doc, 'html')
assert(html == "<p><strong>Tea</strong></p>")

Module pandoc.utils

This module exposes internal pandoc functions and utility functions.

The module is loaded as part of the pandoc module and available as pandoc.utils. In versions up-to and including pandoc 2.6, this module had to be loaded explicitly. Example:

pandoc.utils = require 'pandoc.utils'

Use the above for backwards compatibility.

blocks_to_inlines (blocks[, sep])

Squash a list of blocks into a list of inlines.

Parameters:

blocks
List of Block elements to be flattened.
sep
List of Inline elements inserted as separator between two consecutive blocks; defaults to { pandoc.Space(), pandoc.Str'¶', pandoc.Space()}.

Returns:

Usage:

local blocks = {
  pandoc.Para{ pandoc.Str 'Paragraph1' },
  pandoc.Para{ pandoc.Emph 'Paragraph2' }
}
local inlines = pandoc.utils.blocks_to_inlines(blocks)
-- inlines = {
--   pandoc.Str 'Paragraph1',
--   pandoc.Space(), pandoc.Str'¶', pandoc.Space(),
--   pandoc.Emph{ pandoc.Str 'Paragraph2' }
-- }

equals (element1, element2)

Test equality of AST elements. Elements in Lua are considered equal if and only if the objects obtained by unmarshaling are equal.

This function is deprecated. Use the normal Lua == equality operator instead.

Parameters:

element1, element2
Objects to be compared (any type)

Returns:

  • Whether the two objects represent the same element (boolean)

from_simple_table (table)

Creates a Table block element from a SimpleTable. This is useful for dealing with legacy code which was written for pandoc versions older than 2.10.

Returns:

  • table block element (Table)

Usage:

local simple = pandoc.SimpleTable(table)
-- modify, using pre pandoc 2.10 methods
simple.caption = pandoc.SmallCaps(simple.caption)
-- create normal table block again
table = pandoc.utils.from_simple_table(simple)

make_sections (number_sections, base_level, blocks)

Converts list of Block elements into sections. Divs will be created beginning at each Header and containing following content until the next Header of comparable level. If number_sections is true, a number attribute will be added to each Header containing the section number. If base_level is non-null, Header levels will be reorganized so that there are no gaps, and so that the base level is the level specified.

Parameters:

number_sections
whether section divs should get an additional number attribute containing the section number. (boolean)
base_level
shift top-level headings to this level. (integer|nil)
blocks
list of blocks to process (Blocks)

Returns:

Usage:

local blocks = {
  pandoc.Header(2, pandoc.Str 'first'),
  pandoc.Header(2, pandoc.Str 'second'),
}
local newblocks = pandoc.utils.make_sections(true, 1, blocks)

references

references (doc)

Get references defined inline in the metadata and via an external bibliography. Only references that are actually cited in the document (either with a genuine citation or with nocite) are returned. URL variables are converted to links.

The structure used represent reference values corresponds to that used in CSL JSON; the return value can be use as references metadata, which is one of the values used by pandoc and citeproc when generating bibliographies.

Parameters:

doc
document (Pandoc)

Returns:

  • list of references. (table)

Usage:

-- Include all cited references in document
function Pandoc (doc)
  doc.meta.references = pandoc.utils.references(doc)
  doc.meta.bibliography = nil
  return doc
end

run_json_filter

run_json_filter (doc, filter[, args])

Filter the given doc by passing it through the a JSON filter.

Parameters:

doc
the Pandoc document to filter
filter
filter to run
args
list of arguments passed to the filter. Defaults to {FORMAT}.

Returns:

Usage:

-- Assumes `some_blocks` contains blocks for which a
-- separate literature section is required.
local sub_doc = pandoc.Pandoc(some_blocks, metadata)
sub_doc_with_bib = pandoc.utils.run_json_filter(
  sub_doc,
  'pandoc-citeproc'
)
some_blocks = sub_doc.blocks -- some blocks with bib

normalize_date

normalize_date (date_string)

Parse a date and convert (if possible) to “YYYY-MM-DD” format. We limit years to the range 1601-9999 (ISO 8601 accepts greater than or equal to 1583, but MS Word only accepts dates starting 1601).

Returns:

  • A date string, or nil when the conversion failed.

sha1

sha1 (contents)

Returns the SHA1 has of the contents.

Returns:

  • SHA1 hash of the contents.

Usage:

local fp = pandoc.utils.sha1("foobar")

stringify

stringify (element)

Converts the given element (Pandoc, Meta, Block, or Inline) into a string with all formatting removed.

Returns:

  • A plain string representation of the given element.

Usage:

local inline = pandoc.Emph{pandoc.Str 'Moin'}
-- outputs "Moin"
print(pandoc.utils.stringify(inline))

to_roman_numeral

to_roman_numeral (integer)

Converts an integer < 4000 to uppercase roman numeral.

Returns:

  • A roman numeral string.

Usage:

local to_roman_numeral = pandoc.utils.to_roman_numeral
local pandoc_birth_year = to_roman_numeral(2006)
-- pandoc_birth_year == 'MMVI'

to_simple_table

to_simple_table (table)

Creates a SimpleTable out of a Table block.

Returns:

Usage:

local simple = pandoc.utils.to_simple_table(table)
-- modify, using pre pandoc 2.10 methods
simple.caption = pandoc.SmallCaps(simple.caption)
-- create normal table block again
table = pandoc.utils.from_simple_table(simple)

type

type (value)

Pandoc-friendly version of Lua’s default type function, returning the type of a value. This function works with all types listed in section Lua type reference, except if noted otherwise.

The function works by checking the metafield __name. If the argument has a string-valued metafield __name, then it returns that string. Otherwise it behaves just like the normal type function.

Parameters:

value
any Lua value

Returns:

  • type of the given value (string)

Usage:

-- Prints one of 'string', 'boolean', 'Inlines', 'Blocks',
-- 'table', and 'nil', corresponding to the Haskell constructors
-- MetaString, MetaBool, MetaInlines, MetaBlocks, MetaMap,
-- and an unset value, respectively.
function Meta (meta)
  print('type of metavalue `author`:', pandoc.utils.type(meta.author))
end

Module pandoc.mediabag

The pandoc.mediabag module allows accessing pandoc’s media storage. The “media bag” is used when pandoc is called with the --extract-media or (for HTML only) --self-contained option.

The module is loaded as part of module pandoc and can either be accessed via the pandoc.mediabag field, or explicitly required, e.g.:

local mb = require 'pandoc.mediabag'

delete

delete (filepath)

Removes a single entry from the media bag.

Parameters:

filepath
filename of the item to be deleted. The media bag will be left unchanged if no entry with the given filename exists.

empty

empty ()

Clear-out the media bag, deleting all items.

insert

insert (filepath, mime_type, contents)

Adds a new entry to pandoc’s media bag. Replaces any existing mediabag entry with the same filepath.

Parameters:

filepath
filename and path relative to the output folder.
mime_type
the file’s MIME type; use nil if unknown or unavailable.
contents
the binary contents of the file.

Usage:

local fp = "media/hello.txt"
local mt = "text/plain"
local contents = "Hello, World!"
pandoc.mediabag.insert(fp, mt, contents)

items

items ()

Returns an iterator triple to be used with Lua’s generic for statement. The iterator returns the filepath, MIME type, and content of a media bag item on each invocation. Items are processed one-by-one to avoid excessive memory use.

This function should be used only when full access to all items, including their contents, is required. For all other cases, list should be preferred.

Returns:

  • The iterator function; must be called with the iterator state and the current iterator value.
  • Iterator state – an opaque value to be passed to the iterator function.
  • Initial iterator value.

Usage:

for fp, mt, contents in pandoc.mediabag.items() do
  -- print(fp, mt, contents)
end

list

list ()

Get a summary of the current media bag contents.

Returns: A list of elements summarizing each entry in the media bag. The summary item contains the keys path, type, and length, giving the filepath, MIME type, and length of contents in bytes, respectively.

Usage:

-- calculate the size of the media bag.
local mb_items = pandoc.mediabag.list()
local sum = 0
for i = 1, #mb_items do
    sum = sum + mb_items[i].length
end
print(sum)

lookup

lookup (filepath)

Lookup a media item in the media bag, and return its MIME type and contents.

Parameters:

filepath
name of the file to look up.

Returns:

  • the entry’s MIME type, or nil if the file was not found.
  • contents of the file, or nil if the file was not found.

Usage:

local filename = "media/diagram.png"
local mt, contents = pandoc.mediabag.lookup(filename)

fetch

fetch (source)

Fetches the given source from a URL or local file. Returns two values: the contents of the file and the MIME type (or an empty string).

The function will first try to retrieve source from the mediabag; if that fails, it will try to download it or read it from the local file system while respecting pandoc’s “resource path” setting.

Parameters:

source
path to a resource; either a local file path or URI

Returns:

  • the entries MIME type, or nil if the file was not found.
  • contents of the file, or nil if the file was not found.

Usage:

local diagram_url = "https://pandoc.org/diagram.jpg"
local mt, contents = pandoc.mediabag.fetch(diagram_url)

Module pandoc.List

This module defines pandoc’s list type. It comes with useful methods and convenience functions.

Constructor

pandoc.List([table])

Create a new List. If the optional argument table is given, set the metatable of that value to pandoc.List. This is an alias for pandoc.List:new([table]).

Metamethods

pandoc.List:__concat (list)

Concatenates two lists.

Parameters:

list
second list concatenated to the first

Returns: a new list containing all elements from list1 and list2

pandoc.List:__eq (a, b)

Compares two lists for equality. The lists are taken as equal if and only if they are of the same type (i.e., have the same non-nil metatable), have the same length, and if all elements are equal.

Parameters:

a, b
any Lua object

Returns:

  • true if the two lists are equal, false otherwise.

Methods

pandoc.List:clone ()

Returns a (shallow) copy of the list.

pandoc.List:extend (list)

Adds the given list to the end of this list.

Parameters:

list
list to appended

pandoc.List:find (needle, init)

Returns the value and index of the first occurrence of the given item.

Parameters:

needle
item to search for
init
index at which the search is started

Returns: first item equal to the needle, or nil if no such item exists.

pandoc.List:find_if (pred, init)

Returns the value and index of the first element for which the predicate holds true.

Parameters:

pred
the predicate function
init
index at which the search is started

Returns: first item for which `test` succeeds, or nil if no such item exists.

pandoc.List:filter (pred)

Returns a new list containing all items satisfying a given condition.

Parameters:

pred
condition items must satisfy.

Returns: a new list containing all items for which `test` was true.

pandoc.List:includes (needle, init)

Checks if the list has an item equal to the given needle.

Parameters:

needle
item to search for
init
index at which the search is started

Returns: true if a list item is equal to the needle, false otherwise

pandoc.List:insert ([pos], value)

Inserts element value at position pos in list, shifting elements to the next-greater index if necessary.

This function is identical to table.insert.

Parameters:

pos
index of the new value; defaults to length of the list + 1
value
value to insert into the list

pandoc.List:map (fn)

Returns a copy of the current list by applying the given function to all elements.

Parameters:

fn
function which is applied to all list items.

pandoc.List:new([table])

Create a new List. If the optional argument table is given, set the metatable of that value to pandoc.List.

Parameters:

table
table which should be treatable as a list; defaults to an empty table

Returns: the updated input value

pandoc.List:remove ([pos])

Removes the element at position pos, returning the value of the removed element.

This function is identical to table.remove.

Parameters:

pos
position of the list value that will be removed; defaults to the index of the last element

Returns: the removed element

pandoc.List:sort ([comp])

Sorts list elements in a given order, in-place. If comp is given, then it must be a function that receives two list elements and returns true when the first element must come before the second in the final order (so that, after the sort, i < j implies not comp(list[j],list[i])). If comp is not given, then the standard Lua operator < is used instead.

Note that the comp function must define a strict partial order over the elements in the list; that is, it must be asymmetric and transitive. Otherwise, no valid sort may be possible.

The sort algorithm is not stable: elements considered equal by the given order may have their relative positions changed by the sort.

This function is identical to table.sort.

Parameters:

comp
Comparison function as described above.

Module pandoc.path

Module for file path manipulations.

Static Fields

separator

The character that separates directories.

search_path_separator

The character that is used to separate the entries in the PATH environment variable.

Functions

directory (filepath)

Gets the directory name, i.e., removes the last directory separator and everything after from the given path.

Parameters:

filepath
path (string)

Returns:

  • The filepath up to the last directory separator. (string)

filename (filepath)

Get the file name.

Parameters:

filepath
path (string)

Returns:

  • File name part of the input path. (string)

is_absolute (filepath)

Checks whether a path is absolute, i.e. not fixed to a root.

Parameters:

filepath
path (string)

Returns:

  • true if filepath is an absolute path, false otherwise. (boolean)

is_relative (filepath)

Checks whether a path is relative or fixed to a root.

Parameters:

filepath
path (string)

Returns:

  • true if filepath is a relative path, false otherwise. (boolean)

join (filepaths)

Join path elements back together by the directory separator.

Parameters:

filepaths
path components (list of strings)

Returns:

  • The joined path. (string)

make_relative (path, root[, unsafe])

Contract a filename, based on a relative path. Note that the resulting path will usually not introduce .. paths, as the presence of symlinks means ../b may not reach a/b if it starts from a/c. For a worked example see this blog post.

Set unsafe to a truthy value to a allow .. in paths.

Parameters:

path
path to be made relative (string)
root
root path (string)
unsafe
whether to allow .. in the result. (boolean)

Returns:

  • contracted filename (string)

normalize (filepath)

Normalizes a path.

  • // makes sense only as part of a (Windows) network drive; elsewhere, multiple slashes are reduced to a single path.separator (platform dependent).
  • / becomes path.separator (platform dependent)
  • ./ -> ’’
  • an empty path becomes .

Parameters:

filepath
path (string)

Returns:

  • The normalized path. (string)

split (filepath)

Splits a path by the directory separator.

Parameters:

filepath
path (string)

Returns:

  • List of all path components. (list of strings)

split_extension (filepath)

Splits the last extension from a file path and returns the parts. The extension, if present, includes the leading separator; if the path has no extension, then the empty string is returned as the extension.

Parameters:

filepath
path (string)

Returns:

  • filepath without extension (string)

  • extension or empty string (string)

split_search_path (search_path)

Takes a string and splits it on the search_path_separator character. Blank items are ignored on Windows, and converted to . on Posix. On Windows path elements are stripped of quotes.

Parameters:

search_path
platform-specific search path (string)

Returns:

  • list of directories in search path (list of strings)

Module pandoc.system

Access to system information and functionality.

Static Fields

arch

The machine architecture on which the program is running.

os

The operating system on which the program is running.

Functions

environment

environment ()

Retrieve the entire environment as a string-indexed table.

Returns:

  • A table mapping environment variables names to their string value (table).

get_working_directory

get_working_directory ()

Obtain the current working directory as an absolute path.

Returns:

  • The current working directory (string).

with_environment

with_environment (environment, callback)

Run an action within a custom environment. Only the environment variables given by environment will be set, when callback is called. The original environment is restored after this function finishes, even if an error occurs while running the callback action.

Parameters:

environment
Environment variables and their values to be set before running callback. (table with string keys and string values)
callback
Action to execute in the custom environment (function)

Returns:

  • The result(s) of the call to callback

with_temporary_directory

with_temporary_directory ([parent_dir,] templ, callback)

Create and use a temporary directory inside the given directory. The directory is deleted after the callback returns.

Parameters:

parent_dir
Parent directory to create the directory in (string). If this parameter is omitted, the system’s canonical temporary directory is used.
templ
Directory name template (string).
callback
Function which takes the name of the temporary directory as its first argument (function).

Returns:

  • The result of the call to callback.

with_working_directory

with_working_directory (directory, callback)

Run an action within a different directory. This function will change the working directory to directory, execute callback, then switch back to the original working directory, even if an error occurs while running the callback action.

Parameters:

directory
Directory in which the given callback should be executed (string)
callback
Action to execute in the given directory (function)

Returns:

  • The result(s) of the call to callback

Module pandoc.layout

Plain-text document layouting.

Fields

blankline

Inserts a blank line unless one exists already.

cr

A carriage return. Does nothing if we're at the beginning of a line; otherwise inserts a newline.

empty

The empty document.

space

A breaking (reflowable) space.

Functions

after_break

after_break (text)

Creates a Doc which is conditionally included only if it comes at the beginning of a line.

An example where this is useful is for escaping line-initial . in roff man.

Parameters

text

content to include when placed after a break (string)

Returns

  • new doc (Doc)

before_non_blank

before_non_blank (doc)

Conditionally includes the given doc unless it is followed by a blank space.

Parameters

doc

document (Doc)

Returns

  • conditional doc (Doc)

blanklines

blanklines (n)

Inserts blank lines unless they exist already.

Parameters

n

number of blank lines (integer)

Returns

  • conditional blank lines (Doc)

braces

braces (doc)

Puts the doc in curly braces.

Parameters

doc

document (Doc)

Returns

  • doc enclosed by {}. (Doc)

brackets

brackets (doc)

Puts the doc in square brackets

Parameters

doc

document (Doc)

Returns

  • doc enclosed by []. (Doc)

cblock

cblock (doc, width)

Creates a block with the given width and content, aligned centered.

Parameters

doc

document (Doc)

width

block width in chars (integer)

Returns

  • doc, aligned centered in a block with maxwidth chars per line. (Doc)

chomp

chomp (doc)

Chomps trailing blank space off of the doc.

Parameters

doc

document (Doc)

Returns

  • doc without trailing blanks (Doc)

concat

concat (docs[, sep])

Concatenates a list of Docs.

Parameters

docs

list of Docs ({Doc,...})

sep

separator (default: none) (Doc)

Returns

  • concatenated doc (Doc)

double_quotes

double_quotes (doc)

Wraps a Doc in double quotes.

Parameters

doc

document (Doc)

Returns

  • doc enclosed by " chars (Doc)

flush

flush (doc)

Makes a Doc flush against the left margin.

Parameters

doc

document (Doc)

Returns

  • flushed doc (Doc)

hang

hang (doc, ind, start)

Creates a hanging indent.

Parameters

doc

document (Doc)

ind

indentation width (integer)

start

document (Doc)

Returns

  • doc prefixed by start on the first line, subsequent lines indented by ind spaces. (Doc)

inside

inside (contents, start, end)

Encloses a Doc inside a start and end Doc.

Parameters

contents

document (Doc)

start

document (Doc)

end

document (Doc)

Returns

  • enclosed contents (Doc)

lblock

lblock (doc, width)

Creates a block with the given width and content, aligned to the left.

Parameters

doc

document (Doc)

width

block width in chars (integer)

Returns

  • doc put into block with max width chars per line. (Doc)

literal

literal (text)

Creates a Doc from a string.

Parameters

text

literal value (string)

Returns

  • doc contatining just the literal string (Doc)

nest

nest (doc, ind)

Indents a Doc by the specified number of spaces.

Parameters

doc

document (Doc)

ind

indentation size (integer)

Returns

  • doc indented by ind spaces (Doc)

nestle

nestle (doc)

Removes leading blank lines from a Doc.

Parameters

doc

document (Doc)

Returns

  • doc with leading blanks removed (Doc)

nowrap

nowrap (doc)

Makes a Doc non-reflowable.

Parameters

doc

document (Doc)

Returns

  • same as input, but non-reflowable (Doc)

parens

parens (doc)

Puts the doc in parentheses.

Parameters

doc

document (Doc)

Returns

  • doc enclosed by (). (Doc)

prefixed

prefixed (doc, prefix)

Uses the specified string as a prefix for every line of the inside document (except the first, if not at the beginning of the line).

Parameters

doc

document (Doc)

prefix

prefix for each line (string)

Returns

  • prefixed doc (Doc)

quotes

quotes (doc)

Wraps a Doc in single quotes.

Parameters

doc

document (Doc)

Returns

  • doc enclosed in '. (Doc)

rblock

rblock (doc, width)

Creates a block with the given width and content, aligned to the right.

Parameters

doc

document (Doc)

width

block width in chars (integer)

Returns

  • doc, right aligned in a block with maxwidth chars per line. (Doc)

vfill

vfill (border)

An expandable border that, when placed next to a box, expands to the height of the box. Strings cycle through the list provided.

Parameters

border

vertically expanded characters (string)

Returns

  • automatically expanding border Doc (Doc)

render

render (doc[, colwidth])

Render a @'Doc'@. The text is reflowed on breakable spacesto match the given line length. Text is not reflowed if theline length parameter is omitted or nil.

Parameters

doc

document (Doc)

colwidth

planned maximum line length (integer)

Returns

  • rendered doc (Doc)

is_empty

is_empty (doc)

Checks whether a doc is empty.

Parameters

doc

document (Doc)

Returns

  • true iff doc is the empty document, false otherwise. (boolean)

height

height (doc)

Returns the height of a block or other Doc.

Parameters

doc

document (Doc)

Returns

  • doc height (integer|string)

min_offset

min_offset (doc)

Returns the minimal width of a Doc when reflowed at breakable spaces.

Parameters

doc

document (Doc)

Returns

  • minimal possible width (integer|string)

offset

offset (doc)

Returns the width of a Doc as number of characters.

Parameters

doc

document (Doc)

Returns

  • doc width (integer|string)

real_length

real_length (str)

Returns the real length of a string in a monospace font: 0 for a combining chaeracter, 1 for a regular character, 2 for an East Asian wide character.

Parameters

str

UTF-8 string to measure (string)

Returns

  • text length (integer|string)

update_column

update_column (doc, i)

Returns the column that would be occupied by the last laid out character.

Parameters

doc

document (Doc)

i

start column (integer)

Returns

  • column number (integer|string)

Module pandoc.template

Handle pandoc templates.

compile

compile (template[, templates_path])

Compiles a template string into a Template object usable by pandoc.

If the templates_path parameter is specified, should be the file path associated with the template. It is used when checking for partials. Partials will be taken only from the default data files if this parameter is omitted.

An error is raised if compilation fails.

Parameters:

template
template string (string)
templates_path
parameter to determine a default path and extension for partials; uses the data files templates path by default. (string)

Returns:

  • compiled template (Template)

default

default ([writer])

Returns the default template for a given writer as a string. An error if no such template can be found.

Parameters:

writer
name of the writer for which the template should be retrieved; defaults to the global FORMAT.

Returns:

  • raw template (string)

Module pandoc.types

Constructors for types which are not part of the pandoc AST.

Version

Version (version_specifier)

Creates a Version object.

Parameters:

version_specifier
Version specifier: this can be a version string like '2.7.3', a list of integers like {2, 7, 3}, a single integer, or a Version.

Returns:

  • ITEM 1
  • ITEM 2
  • ITEM 3

RIGHT BOX

RIGHT TEXT