curly_braces_style {roger}

Validation of the Positioning of Braces

Description

Check that the opening and closing braces are positioned according to standard bracing styles rules.

Usage

close_brace_style(srcData)
open_brace_style(srcData, style = c("R", "1TBS"))
open_brace_unique_style(srcData)

Arguments

srcData

a list as returned by getSourceData.

style

character string of a supported bracing style.

Details

Good coding practices dictate to use one bracing style uniformly in a script.

The "R" bracing style has both opening and closing braces on their own lines, left aligned with their corresponding statement:

    if (x > 0)
    {
        ...
    }
  

The "1TBS" bracing style, also known at "K&R" style, has the opening brace immediately follow its corresponding statement, separated by a space. The closing brace lies on its own line, left aligned with the statement:

    if (x > 0) {
        ...
    }
  

open_brace_style validates that the coding style in argument is used for opening braces in a script file. open_brace_unique_style validates that only one style is used throughout the script.

These functions use getParseText and, therefore, require that the "keep.source" option is TRUE.

Value

Boolean. When FALSE, a message indicates the nature of the error and the faulty lines, and the returned value has the following attributes:

lines

faulty line numbers;

message

text of the error message.

Examples

## Keep parse data in non interactive sessions.
if (!interactive())
    op <- options(keep.source = TRUE)

## Correct positioning of braces in R bracing style
fil <- tempfile(fileext = ".R")
cat("x <- 2",
    "if (x <= 2)",
    "{",
    "    y <- 3",
    "    x + y",
    "}",
    file = fil, sep = "\n")
srcData <- getSourceData(fil)
open_brace_style(srcData, style = "R")
close_brace_style(srcData)

## Above code in invalid in 1TBS bracing style
open_brace_style(srcData, style = "1TBS")

## Incorrect positioning of the opening brace and
## misalignment of the closing brace
fil <- tempfile(fileext = ".R")
cat("f <- function(x) {",
    "    x^2",
    "  }",
    file = fil, sep = "\n")
srcData <- getSourceData(fil)
open_brace_style(srcData, style = "R")
close_brace_style(srcData)

## Incorrect simultaneous use of two bracing styles
fil <- tempfile(fileext = ".R")
cat("x <- 2",
    "if (x <= 2)",
    "{",
    "    y <- 3",
    "    x + y",
    "}",
    "for (i in 1:5) {",
    "    x + i",
    "}",
    file = fil, sep = "\n")
open_brace_unique_style(getSourceData(fil))