Evaluate code and syntax highlight the results

This function runs code and captures the output using evaluate::evaluate(). It syntax higlights code with highlight(), and intermingles it with output.

evaluate_and_highlight(
  code,
  fig_save,
  classes = downlit::classes_pandoc(),
  env = NULL,
  output_handler = evaluate::new_output_handler(),
  highlight = TRUE
)

Arguments

code

Code to evaluate (as a string).

fig_save

A function with arguments plot and id that is responsible for saving plot to a file (using id to disambiguate multiple plots in the same chunk). It should return a list with components path, width, and height.

classes

A mapping between token names and CSS class names. Bundled classes_pandoc() and classes_chroma() provide mappings that (roughly) match Pandoc and chroma (used by hugo) classes so you can use existing themes.

env

Environment in which to evaluate code; if not supplied, defaults to a child of the global environment.

output_handler

Custom output handler for evaluate::evaluate().

highlight

Optionally suppress highlighting. This is useful for tests.

Value

An string containing HTML with a dependencies attribute giving an additional htmltools dependencies required to render the HTML.

Examples

cat(evaluate_and_highlight("1 + 2"))
#> <span class='r-in'><span><span class='fl'>1</span> <span class='op'>+</span> <span class='fl'>2</span></span></span>
#> <span class='r-out co'><span class='r-pr'>#&gt;</span> [1] 3</span>
cat(evaluate_and_highlight("x <- 1:10\nmean(x)"))
#> <span class='r-in'><span><span class='va'>x</span> <span class='op'>&lt;-</span> <span class='fl'>1</span><span class='op'>:</span><span class='fl'>10</span></span></span>
#> <span class='r-in'><span><span class='fu'><a href='https://rdrr.io/r/base/mean.html'>mean</a></span><span class='op'>(</span><span class='va'>x</span><span class='op'>)</span></span></span>
#> <span class='r-out co'><span class='r-pr'>#&gt;</span> [1] 5.5</span>

# -----------------------------------------------------------------
# evaluate_and_highlight() powers pkgdown's documentation formatting so
# here I include a few examples to make sure everything looks good
# -----------------------------------------------------------------

blue <- function(x) paste0("\033[34m", x, "\033[39m")
f <- function(x) {
  cat("This is some output. My favourite colour is ", blue("blue"), ".\n", sep = "")
  message("This is a message. My favourite fruit is ", blue("blueberries"))
  warning("Now at stage ", blue("blue"), "!")
}
f()
#> This is some output. My favourite colour is blue.
#> This is a message. My favourite fruit is blueberries
#> Warning: Now at stage blue!

plot(1:10)