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authorJohn MacFarlane <jgm@berkeley.edu>2017-12-28 22:02:59 -0800
committerJohn MacFarlane <jgm@berkeley.edu>2017-12-28 22:02:59 -0800
commit246e8f081a0cc78fe67160124df9f2e54cd652a3 (patch)
treefa5065b389f7d08b30266112d37e3e04e34bdc78
parent108e429c8843992e892a8e129baa7152d5abc5f9 (diff)
Update lua-filters.md and the tool that generates it.
-rw-r--r--doc/lua-filters.md288
-rw-r--r--tools/update-lua-docs.lua2
2 files changed, 108 insertions, 182 deletions
diff --git a/doc/lua-filters.md b/doc/lua-filters.md
index 07de33259..c99625e67 100644
--- a/doc/lua-filters.md
+++ b/doc/lua-filters.md
@@ -1,9 +1,9 @@
---
-title: Pandoc Lua Filters
author:
- Albert Krewinkel
- John MacFarlane
date: 'December 6, 2017'
+title: Pandoc Lua Filters
---
# Introduction
@@ -37,7 +37,7 @@ JSON to stdout and reading it from stdin.
Here is an example of a lua filter that converts strong emphasis
to small caps:
-``` lua
+``` {.lua}
return {
{
Strong = function (elem)
@@ -49,7 +49,7 @@ return {
or equivalently,
-``` lua
+``` {.lua}
function Strong(elem)
return pandoc.SmallCaps(elem.c)
end
@@ -88,10 +88,10 @@ 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
+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.
+`--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
@@ -132,8 +132,8 @@ function. Two fallback functions are supported, `Inline` and
Elements without matching functions are left untouched.
-See [module documentation](#module-pandoc) for a list of
-pandoc elements.
+See [module documentation](#module-pandoc) for a list of pandoc
+elements.
The global `FORMAT` is set to the format of the pandoc writer
being used (`html5`, `latex`, etc.), so the behavior of a filter
@@ -165,18 +165,18 @@ those elements accessible through the filter function parameter.
Some pandoc functions have been made available in lua:
-- [`walk_block`](#walk_block) and [`walk_inline`](#walk_inline)
- allow filters to be applied inside specific block or inline
- elements;
-- [`read`](#read) allows filters to parse strings into pandoc
- documents;
-- [`pipe`](#pipe) runs an external command with input from and
- output to strings;
-- the [`pandoc.mediabag`](#module-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-pandoc.utils) module contains
- various utility functions.
+- [`walk_block`](#walk_block) and
+ [`walk_inline`](#walk_inline) allow filters to be applied
+ inside specific block or inline elements;
+- [`read`](#read) allows filters to parse strings into pandoc
+ documents;
+- [`pipe`](#pipe) runs an external command with input from and
+ output to strings;
+- the [`pandoc.mediabag`](#module-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-pandoc.utils) module contains
+ various utility functions.
# Lua interpreter initialization
@@ -185,7 +185,7 @@ placing a file `init.lua` in pandoc's data directory. The
default init file loads the `pandoc` and `pandoc.mediabag`
modules:
-``` lua
+``` {.lua}
pandoc = require 'pandoc'
pandoc.mediabag = require 'pandoc.mediabag'
```
@@ -196,7 +196,7 @@ adds all unicode-aware functions defined in the [`text`
module](#module-text) to the default `string` module, prefixed
with the string `uc_`.
-```lua
+``` {.lua}
for name, fn in pairs(require 'text') do
string['uc_' .. name] = fn
end
@@ -205,7 +205,6 @@ end
This makes it possible to apply these functions on strings using
colon syntax (`mystring:uc_upper()`).
-
# Examples
## Macro substitution.
@@ -213,7 +212,7 @@ colon syntax (`mystring:uc_upper()`).
The following filter converts the string `{{helloworld}}` into
emphasized text "Hello, World".
-``` lua
+``` {.lua}
return {
{
Str = function (elem)
@@ -233,7 +232,7 @@ This filter causes metadata defined in an external file
(`metadata-file.yaml`) to be used as default values in a
document's metadata:
-``` lua
+``` {.lua}
-- read metadata file into string
local metafile = io.open('metadata-file.yaml', 'r')
local content = metafile:read("*a")
@@ -260,7 +259,7 @@ return {
This filter sets the date in the document's metadata to the
current date:
-``` lua
+``` {.lua}
function Meta(m)
m.date = os.date("%B %e, %Y")
return m
@@ -272,7 +271,7 @@ end
This filter prints a table of all the URLs linked to in the
document, together with the number of links to that URL.
-``` lua
+``` {.lua}
links = {}
function Link (el)
@@ -313,7 +312,7 @@ 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:
-``` lua
+``` {.lua}
local vars = {}
function get_vars (meta)
@@ -368,13 +367,12 @@ will output:
## 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_block` to transform inline elements
-inside headers), removes footnotes, and replaces links
-with regular text.
+This is the filter we use when converting `MANUAL.txt` to man
+pages. It converts level-1 headers to uppercase (using
+`walk_block` to transform inline elements inside headers),
+removes footnotes, and replaces links with regular text.
-``` lua
+``` {.lua}
-- we use preloaded text to get a UTF-8 aware 'upper' function
local text = require('text')
@@ -398,13 +396,13 @@ 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.)
+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.)
-``` lua
+``` {.lua}
-- creates a handout from an article, using its headings,
-- blockquotes, numbered examples, figures, and any
-- Divs with class "handout"
@@ -427,14 +425,13 @@ 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`.
-
-``` lua
+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`.
+
+``` {.lua}
-- counts words in a document
words = 0
@@ -468,18 +465,18 @@ 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
+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
<http://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`.
+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`.
-``` lua
+``` {.lua}
-- Pandoc filter to process code blocks with class "abc" containing
-- ABC notation into images.
--
@@ -511,18 +508,17 @@ 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 (if necessary) from pdf to png format using
-ImageMagick's `convert`, 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.)
-
-```lua
+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 (if
+necessary) from pdf to png format using ImageMagick's `convert`,
+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.)
+
+``` {.lua}
local function tikz2image(src, filetype, outfile)
local tmp = os.tmpname()
local tmpdir = string.match(tmp, "^(.*[\\/])") or "."
@@ -572,33 +568,31 @@ end
Example of use:
-```
-pandoc --lua-filter tikz.lua -s -o cycle.html <<EOF
-Here is a diagram of the cycle:
+ pandoc --lua-filter tikz.lua -s -o cycle.html <<EOF
+ Here is a diagram of the cycle:
-\begin{tikzpicture}
+ \begin{tikzpicture}
-\def \n {5}
-\def \radius {3cm}
-\def \margin {8} % margin in angles, depends on the radius
+ \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
-```
+ \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
# Module text
UTF-8 aware text manipulation functions, implemented in Haskell.
-These are available to any lua filter. However, the module must
+These are available to any lua filter. However, the module must
be explicitly loaded:
-```lua
+``` {.lua}
-- uppercase all regular text in a document:
text = require 'text'
function Str (s)
@@ -628,7 +622,6 @@ end
: Returns a substring of a UTF-8 string, using lua's string
indexing rules.
-
# Module pandoc
Lua functions for pandoc scripts.
@@ -740,7 +733,7 @@ Lua functions for pandoc scripts.
`content`:
: list of items
- Returns: block quote element
+ Returns: bullet list element
[`CodeBlock (text[, attr])`]{#CodeBlock}
@@ -766,7 +759,7 @@ Lua functions for pandoc scripts.
`content`:
: list of items
- Returns: block quote element
+ Returns: definition list element
[`Div (content[, attr])`]{#Div}
@@ -780,11 +773,11 @@ Lua functions for pandoc scripts.
`attr`:
: element attributes
- Returns: code block element
+ Returns: div element
[`Header (level, content[, attr])`]{#Header}
-: Creates a block quote element.
+: Creates a header element.
Parameters:
@@ -814,7 +807,7 @@ Lua functions for pandoc scripts.
`content`:
: inline content
- Returns: block quote element
+ Returns: line block element
[`Null ()`]{#Null}
@@ -834,7 +827,7 @@ Lua functions for pandoc scripts.
`listAttributes`:
: list parameters
- Returns:
+ Returns: ordered list element
[`Para (content)`]{#Para}
@@ -845,7 +838,7 @@ Lua functions for pandoc scripts.
`content`:
: inline content
- Returns: block quote element
+ Returns: paragraph element
[`Plain (content)`]{#Plain}
@@ -856,7 +849,7 @@ Lua functions for pandoc scripts.
`content`:
: inline content
- Returns: block quote element
+ Returns: plain element
[`RawBlock (format, text)`]{#RawBlock}
@@ -870,7 +863,7 @@ Lua functions for pandoc scripts.
`text`:
: string content
- Returns: block quote element
+ Returns: raw block element
[`Table (caption, aligns, widths, headers, rows)`]{#Table}
@@ -893,7 +886,7 @@ Lua functions for pandoc scripts.
`rows`:
: table rows
- Returns: block quote element
+ Returns: table element
## Inline
@@ -1181,6 +1174,16 @@ Lua functions for pandoc scripts.
## Helpers
+[`apairs (value)`]{#apairs}
+
+: Return an iterator which returns key-value pairs of an
+ associative list.
+
+ Parameters:
+
+ `value`:
+ : },\...} alist associative list
+
[`Attr ([identifier[, classes[, attributes]]])`]{#Attr}
: Create a new set of attributes (Attr).
@@ -1334,61 +1337,6 @@ Lua functions for pandoc scripts.
## Helper Functions
-[`walk_block (element, filter)`]{#walk_block}
-
-: 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)`]{#walk_inline}
-
-: 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])`]{#read}
-
-: Parse the given string into a Pandoc document.
-
- Parameters:
-
- `markup`:
- : the markup to be parsed
-
- `format`:
- : format specification, defaults to \"markdown\".
-
- Returns: pandoc document
-
- 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")
-
[`global_filter ()`]{#global_filter}
: Use functions defined in the global namespace to create a
@@ -1399,35 +1347,14 @@ Lua functions for pandoc scripts.
Usage:
-- within a file defining a pandoc filter:
- local text = require('text')
function Str(text)
- return pandoc.Str(text.upper(text))
+ return pandoc.Str(utf8.upper(text))
end
return {pandoc.global_filter()}
- -- the above is equivalent to
+ -- the above is equivallent to
-- return {{Str = Str}}
-[`pipe (command, args, input)`]{#pipe}
-
-: Runs command with arguments, passing it some input,
- and returns the output.
-
- Returns:
-
- - Output of command.
-
- 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")
-
-
# Module pandoc.utils
This module exposes internal pandoc functions and utility
@@ -1501,7 +1428,7 @@ functions.
[`to_roman_numeral (integer)`]{#utils-to_roman_numeral}
-: Converts an integer < 4000 to uppercase roman numeral.
+: Converts an integer \< 4000 to uppercase roman numeral.
Returns:
@@ -1513,7 +1440,6 @@ functions.
local pandoc_birth_year = to_roman_numeral(2006)
-- pandoc_birth_year == 'MMVI'
-
# Module pandoc.mediabag
The `pandoc.mediabag` module allows accessing pandoc's media
@@ -1583,9 +1509,9 @@ storage. The "media bag" is used when pandoc is called with the
[`fetch (source, base_url)`]{#mediabag-fetch}
-: 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).
+: 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).
Returns:
diff --git a/tools/update-lua-docs.lua b/tools/update-lua-docs.lua
index daa685269..7c5e86d17 100644
--- a/tools/update-lua-docs.lua
+++ b/tools/update-lua-docs.lua
@@ -36,7 +36,7 @@ function Header (el)
return module_blocks{'data/pandoc.lua'}
elseif el.identifier == "module-pandoc.list" then
in_module_section = true
- return module_blocks{'data/List.lua'}
+ return module_blocks{'data/pandoc.List.lua'}
end
end