tidy_source: Reformat R code while preserving blank lines and comments

Description

This function returns reformatted source code; it tries to preserve blank lines and comments, which is different with parse and deparse. It can also replace = with <- where = means assignments, and reindent code by a specified number of spaces (default is 4).

Usage

tidy_source(source = "clipboard", comment = getOption("formatR.comment", 
    TRUE), blank = getOption("formatR.blank", TRUE), arrow = getOption("formatR.arrow", 
    FALSE), brace.newline = getOption("formatR.brace.newline", FALSE), 
    indent = getOption("formatR.indent", 4), output = TRUE, text = NULL, 
    width.cutoff = getOption("width"), ...)

Arguments

source

a character string: location of the source code (default to be the clipboard; this means we can copy the code to clipboard and use tidy_source() without specifying the argument source)

comment

whether to keep comments (TRUE by default)

blank

whether to keep blank lines (TRUE by default)

arrow

whether to replace the assign operator = with <-

brace.newline

whether to put the left brace { to a new line (default FALSE)

indent

number of spaces to indent the code (default 4)

output

output to the console or a file using cat?

text

an alternative way to specify the input: if it is NULL, the function will read the source code from the source argument; alternatively, if text is a character vector containing the source code, it will be used as the input and the source argument will be ignored

width.cutoff

passed to deparse: integer in [20, 500] determining the cutoff at which line-breaking is tried (default to be getOption("width"))

...

other arguments passed to cat, e.g. file (this can be useful for batch-processing R scripts, e.g. tidy_source(source = 'input.R', file = 'output.R'))

Value

A list with components

text.tidy

the reformatted code as a character vector

text.mask

the code containing comments, which are masked in assignments or with the weird operator

References

https://yihui.name/formatR (an introduction to this package, with examples and further notes)

Examples

Run this code

# NOT RUN {
library(formatR)

## a messy R script
messy = system.file("format", "messy.R", package = "formatR")
tidy_source(messy)

## use the 'text' argument
src = readLines(messy)

## source code
cat(src, sep = "\n")

## the formatted version
tidy_source(text = src)

## preserve blank lines
tidy_source(text = src, blank = TRUE)

## indent with 2 spaces
tidy_source(text = src, indent = 2)

## discard comments!
tidy_source(text = src, comment = FALSE)

## wanna see the gory truth??
tidy_source(text = src, output = FALSE)$text.mask


## tidy up the source code of image demo
x = file.path(system.file(package = "graphics"), "demo", "image.R")

# to console
tidy_source(x)

# to a file
f = tempfile()
tidy_source(x, blank = TRUE, file = f)

## check the original code here and see the difference
file.show(x)
file.show(f)

## use global options
options(comment = TRUE, blank = FALSE)
tidy_source(x)

## if you've copied R code into the clipboard
if (interactive()) {
    tidy_source("clipboard")
    ## write into clipboard again
    tidy_source("clipboard", file = "clipboard")
}

## the if-else structure
tidy_source(text = c("{if(TRUE)1 else 2; if(FALSE){1+1", "## comments", "} else 2}"))
# }