highlight (version 0.2-0)

highlight: syntax highlighting based on the R parser

Description

The highlight function performs syntax highlighting based on the results of the parser and the investigation of a detective.

Usage

highlight(file, output = stdout(), detective = simple_detective, renderer, 
	encoding = "unknown", parser.output = parser(file, encoding = encoding), 
	styles = detective(parser.output), expr = NULL, final.newline = FALSE, 
	showPrompts = FALSE, prompt = getOption("prompt"), continue = getOption("continue"), 
	initial.spaces = TRUE, ...)

Arguments

file

code file to parse. This is only used if the parser.output is given

output

where to write the rendered text. If this is anything else than the default (standard output), the sink function is used to redirect the standard output to the output.

detective

the detective chooses the style to apply to each token, basing its investigation on the results of the parser

renderer

highlight delegates rendering the information to the renderer. This package includes html and latex renderers. See renderer_html and renderer_latex

encoding

encoding to assume for the file. the argument is directly passed to the parser.

parser.output

output from the parser. If this is given, the arguments file and encoding are not used

styles

result of the detective investigation. A character vector with as many elements as there are tokens in the parser output

expr

In case we want to render only one expression and not the full parse tree, this argument can be used to specify which expression to render. The default (NULL) means render all expressions. This feature is used by the sweave driver shipped with this packa

final.newline

logical. Indicates if a newline character is added after all tokens.

showPrompts

if TRUE, the highlighted text will show standard and continue prompt

prompt

standard prompt

continue

continue prompt

initial.spaces

should initial spaces be displayed or skipped.

...

additional arguments, currently ignored.

Value

• The resulting formatted text is returned invisibly. It is also written to the output if the output is not NULL

See Also

renderer_html and renderer_latex are the two implementation of renderers currently available in this package. The xterm256 package defines an additional renderer that uses xterm escape sequences. simple_detective is an example detective which does a very simple investigation.

Examples

tf <- tempfile()
	dump( "jitter", file = tf )
	highlight( file = tf, detective = simple_detective, 
		renderer = renderer_html( document = TRUE ) )
	highlight( file = tf, detective = simple_detective, 
		renderer = renderer_latex( document = TRUE ) )
		
	# verbatim renderer that upper cases function names
	uppercase_formatter <- function( tokens, styles, ...){
		out <- tokens
		fcalls <- styles == "functioncall"
		out[ fcalls ] <- casefold( out[ fcalls ], upper = TRUE )
		out
	}
	uppercase_renderer <- renderer_verbatim( 
		formatter = uppercase_formatter )
	# to debug the formatter, use this : 
	# debug( uppercase_renderer$formatter )
	# because this will not work:
	# debug( uppercase_formatter )
	highlight( file = tf, detective = simple_detective, 
		renderer = uppercase_renderer )