markdown (version 1.12)

mark: Render Markdown to an output format

Description

Render Markdown to an output format via the commonmark package. The function mark_html() is a shorthand of mark(format = 'html', template = TRUE), and mark_latex() is a shorthand of mark(format = 'latex', template = TRUE).

Usage

mark(
  file = NULL,
  output = NULL,
  text = NULL,
  format = c("html", "latex"),
  options = NULL,
  template = FALSE,
  meta = list()
)
mark_html(..., template = TRUE)
mark_latex(..., template = TRUE)

Value

Invisible NULL when output is to a file, otherwise a character vector of the rendered output.

Arguments

file

Path to an input file. If not provided, it is presumed that the text argument will be used instead. This argument can also take a character vector of Markdown text directly. To avoid ambiguity in the latter case, a single character string input will be treated as a file if the file exists. If a string should be treated as Markdown text when it happens to be a file path, wrap it in I().

output

Output file path. If not character, the results will be returned as a character vector. If not specified and the input is a file path, the output file path will have the same base name as the input file, with an extension corresponding to the format argument, e.g., mark('foo.md', format = 'latex') will generate an output file foo.tex by default.

text

A character vector of the Markdown text. By default, it is read from file.

format

An output format supported by commonmark, e.g., 'html', 'man', and 'text', etc. See the markdown_*() renderers in commonmark.

options

Options to be passed to the renderer. See markdown_options() for details. This argument can take either a character vector of the form "+option1 option2-option3" (use + or a space to enable an option, and - to disable an option), or a list of the form list(option1 = value1, option2 = value2, ...). A string "+option1" is equivalent to list(option1 = TRUE), and "-option2" means list(option2 = FALSE). Options that do not take logical values must be specified via a list, e.g., list(width = 30).

template

Path to a template file. The default value is getOption('markdown.FORMAT.template', markdown:::pkg_file('resources', 'markdown.FORMAT')) where FORMAT is the output format name (html or latex). It can also take a logical value: TRUE means to use the default template, and FALSE means to generate only a fragment without using any template.

meta

A named list of metadata. Elements in the metadata will be used to fill out the template by their names and values, e.g., list(title = ...) will replace the $title$ variable in the template. See the Section “YAML metadata” in the vignette vignette('intro', package = 'markdown') for supported variables.

...

Arguments to be passed to mark().

See Also

The spec of GitHub Flavored Markdown: https://github.github.com/gfm/

Examples

library(markdown)
mark(c("Hello _World_!", "", "Welcome to **markdown**."))
# a few corner cases
mark(character(0))
mark("")
# if input happens to be a file path but should be treated as text, use I()
mark(I("This is *not* a file.md"))
# that's equivalent to
mark(text = "This is *not* a file.md")

mark_html("Hello _World_!", template = FALSE)
# write HTML to an output file
mark_html("_Hello_, **World**!", output = tempfile())

mark_latex("Hello _World_!", template = FALSE)