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pattern.R
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#' All built-in patterns
#'
#' This object is a named list of all built-in patterns.
#' @references Usage: \url{https://yihui.org/knitr/patterns/}
#' @export
#' @seealso \code{\link{knit_patterns}}
#' @examples all_patterns$rnw; all_patterns$html
#'
#' str(all_patterns)
all_patterns = list(
`rnw` = list(
chunk.begin = '^\\s*<<(.*)>>=.*$', chunk.end = '^\\s*@\\s*(%+.*|)$',
inline.code = '\\\\Sexpr\\{([^}]+)\\}', inline.comment = '^\\s*%.*',
ref.chunk = '^\\s*<<(.+)>>\\s*$', header.begin = '(^|\n)\\s*\\\\documentclass[^}]+\\}',
document.begin = '\\s*\\\\begin\\{document\\}'),
`brew` = list(inline.code = '<%[=]{0,1}\\s+([^%]+)\\s+[-]*%>'),
`tex` = list(
chunk.begin = '^\\s*%+\\s*begin.rcode\\s*(.*)', chunk.end = '^\\s*%+\\s*end.rcode',
chunk.code = '^\\s*%+', ref.chunk = '^%+\\s*<<(.+)>>\\s*$',
inline.comment = '^\\s*%.*', inline.code = '\\\\rinline\\{([^}]+)\\}',
header.begin = '(^|\n)\\s*\\\\documentclass[^}]+\\}',
document.begin = '\\s*\\\\begin\\{document\\}'),
`html` = list(
chunk.begin = '^\\s*<!--\\s*begin.rcode\\s*(.*)',
chunk.end = '^\\s*end.rcode\\s*-->', ref.chunk = '^\\s*<<(.+)>>\\s*$',
inline.code = '<!--\\s*rinline(.+?)-->', header.begin = '\\s*<head>'),
`md` = list(
chunk.begin = '^[\t >]*```+\\s*\\{([a-zA-Z0-9_]+( *[ ,].*)?)\\}\\s*$',
chunk.end = '^[\t >]*```+\\s*$',
ref.chunk = '^\\s*<<(.+)>>\\s*$',
inline.code = '(?<!(^``))(?<!(\n``))`r[ #]([^`]+)\\s*`'),
`rst` = list(
chunk.begin = '^\\s*[.][.]\\s+\\{r(.*)\\}\\s*$',
chunk.end = '^\\s*[.][.]\\s+[.][.]\\s*$', chunk.code = '^\\s*[.][.]',
ref.chunk = '^\\.*\\s*<<(.+)>>\\s*$', inline.code = ':r:`([^`]+)`'),
`asciidoc` = list(
chunk.begin = '^//\\s*begin[.]rcode(.*)$', chunk.end = '^//\\s*end[.]rcode\\s*$',
chunk.code = '^//+', ref.chunk = '^\\s*<<(.+)>>\\s*$',
inline.code = '`r +([^`]+)\\s*`|[+]r +([^+]+)\\s*[+]',
inline.comment = '^//.*'),
`textile` = list(
chunk.begin = '^###[.]\\s+begin[.]rcode(.*)$',
chunk.end = '^###[.]\\s+end[.]rcode\\s*$',
ref.chunk = '^\\s*<<(.+)>>\\s*$',
inline.code = '@r +([^@]+)\\s*@',
inline.comment = '^###[.].*')
)
.sep.label = '^(#|--)+\\s*(@knitr|----+)(.*?)-*\\s*$' # pattern for code chunks in an R script
# initial pattern list
.pat.init = list(
chunk.begin = NULL, chunk.end = NULL, chunk.code = NULL, inline.code = NULL,
global.options = NULL, input.doc = NULL, ref.chunk = NULL,
header.begin = NULL, document.begin = NULL
)
#' Patterns to match and extract R code in a document
#'
#' Patterns are regular expressions and will be used in functions like
#' \code{base::\link{grep}()} to extract R code and chunk options. The object
#' \code{knit_patterns} controls the patterns currently used; see the references
#' and examples for usage. All built-in patterns are available in the list
#' \link{all_patterns}.
#'
#' @seealso \code{\link{all_patterns}}
#' @references Usage: \url{https://yihui.org/knitr/objects/}
#'
#' Components in \code{knit_patterns}: \url{https://yihui.org/knitr/patterns/}
#' @export
#' @examples library(knitr)
#' opat = knit_patterns$get() # old pattern list (to restore later)
#'
#' apats = all_patterns # a list of all built-in patterns
#' str(apats)
#' knit_patterns$set(apats[['rnw']]) # set pattern list from apats
#'
#' knit_patterns$get(c('chunk.begin', 'chunk.end', 'inline.code'))
#'
#' # a customized pattern list; has to empty the original patterns first!
#' knit_patterns$restore()
#' # we may want to use this in an HTML document
#' knit_patterns$set(list(chunk.begin = '<!--helloR\\s+(.*)', chunk.end = '^byeR-->'))
#' str(knit_patterns$get())
#'
#' knit_patterns$set(opat) # put the old patterns back
knit_patterns = new_defaults(.pat.init)
# in LaTeX, may need to put this \newcommand{\rinline}[1]{R output}
# convenience functions
set_pattern = function(type) {
knit_patterns$restore(all_patterns[[type]])
}
#' Set regular expressions to read input documents
#'
#' These are convenience functions to set pre-defined pattern lists (the syntax
#' to read input documents). The function names are built from corresponding
#' file extensions, e.g. \code{pat_rnw()} can set the Sweave syntax to read Rnw
#' documents.
#' @rdname pat_fun
#' @return The patterns object \code{\link{knit_patterns}} is modified as a side
#' effect.
#' @export pat_rnw pat_brew pat_tex pat_html pat_md pat_rst pat_asciidoc pat_textile
#' @examples # see how knit_patterns is modified
#' knit_patterns$get(); pat_rnw(); knit_patterns$get()
#'
#' knit_patterns$restore() # empty the list
pat_rnw = function() set_pattern('rnw')
#' @rdname pat_fun
pat_brew = function() set_pattern('brew')
#' @rdname pat_fun
pat_tex = function() set_pattern('tex')
#' @rdname pat_fun
pat_html = function() set_pattern('html')
#' @rdname pat_fun
pat_md = function() set_pattern('md')
#' @rdname pat_fun
pat_rst = function() set_pattern('rst')
#' @rdname pat_fun
pat_asciidoc = function() set_pattern('asciidoc')
#' @rdname pat_fun
pat_textile = function() set_pattern('textile')
# helper functions
# is it a group pattern?
group_pattern = function(pattern) {
!is.null(pattern) && grepl('\\(.+\\)', pattern)
}
# automatically detect the chunk patterns
detect_pattern = function(text, ext) {
if (!missing(ext)) {
ext = tolower(ext)
if (ext %in% c('rnw', 'snw', 'stex')) return('rnw')
if (ext == 'brew') return('brew')
if (ext %in% c('htm', 'html', 'rhtm', 'rhtml')) return('html')
if (ext %in% c('rmd', 'rmarkdown', 'markdown', 'md', 'qmd')) return('md')
if (ext %in% c('rst', 'rrst')) return('rst')
if (ext %in% c('asciidoc', 'rasciidoc', 'adoc', 'radoc')) return('asciidoc')
}
for (p in names(all_patterns)) {
for (i in c('chunk.begin', 'inline.code')) {
pat = all_patterns[[p]][[i]]
if (length(pat) && any(grepl(pat, text, perl = TRUE))) return(p)
}
}
# *.Rtex indicates the tex syntax in knitr, but Rnw syntax in traditional
# Sweave, which should have been detected in the above loop
if (!missing(ext) && ext == 'rtex') return('rnw')
NULL
}