hilight: Syntax highlight an R code fragment

View source: R/highlight.R

hilightR Documentation

Syntax highlight an R code fragment


This function parses the R code, fetches the tokens in it (getParseData), and attach syntax highlighting commands onto them. With proper style definitions for these commands (such as colors or font styles), the R code will be syntax highlighted in the LaTeX/HTML output. The two functions hi_latex and hi_html are wrappers of hilight for LaTeX and HTML output, respectively.


  format = c("latex", "html"),
  prompt = FALSE,
  fallback = FALSE

hi_latex(code, ...)

hi_html(code, ...)



a character string (the R source code)


the output format


a data frame of two columns containing the markup commands


whether to add prompts to the code


whether to use the fallback method, i.e. the regular expression based method; this method is not precise and only highlights a few types of symbols such as comments, strings and functions; fallback will be set to TRUE when the input code fails to be parsed


arguments to be passed to hilight()


For the markup data frame, the first column is put before the R tokens, and the second column is behind; the row names of the data frame must be the R token names; a special row is named STANDARD, which contains the markup for the standard tokens (i.e. those that do not need to be highlighted); if missing, the built-in data frames highr:::cmd_latex and highr:::cmd_html will be used.

This function only binds markups onto R tokens, and the real syntax highlighting must be done with style definitions, which is out of the scope of this package. It was designed to be used as the syntax highlighting infrastructure of other packages such as knitr, where the colors and font styles are properly defined in the LaTeX preamble and HTML header.


A character vector for the syntax highlighted code.


Yihui Xie and Yixuan Qiu

See Also

See the package vignettes browseVignettes('highr') for how this function works internally.


hilight("x=1 # assignment")

txt = c("a <- 1 # something", "c(y=\"world\", z=\"hello\")", "b=function(x=5) {",
    "for(i in 1:10) {
  if (i < x) print(i) else break}}", "z@child # S4 slot",
    "'special chars <>#$%&_{}'")
cat(hi_latex(txt), sep = "\n")
cat(hi_html(txt), sep = "\n")

# the markup data frames

highr documentation built on Dec. 28, 2022, 2:33 a.m.

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