The R Project SVN R

require("tools")

## BOM stripping in .file_append_ensuring_LFs()

BOM <- as.raw(c(0xEF, 0xBB, 0xBF))

collate <- function(files, enc = NA_character_) {

    out <- tempfile(); file.create(out)

    tools:::.file_append_ensuring_LFs(out, files, enc = enc)

    readBin(out, "raw", file.info(out)$size)

}

has_bom <- function(raw) length(grepRaw(BOM, raw, fixed = TRUE)) > 0L

## File with BOM

f_bom <- tempfile(); writeBin(c(BOM, charToRaw("x <- 1\n")), f_bom)

## File without BOM

f_plain <- tempfile(); writeBin(charToRaw("y <- 2\n"), f_plain)

## BOM-only file

f_bomonly <- tempfile(); writeBin(BOM, f_bomonly)

## Short file (< 3 bytes)

f_short <- tempfile(); writeBin(charToRaw("z\n"), f_short)

stopifnot(exprs = {

    ## enc = NA preserves BOM

    has_bom(collate(f_bom))

    grepl("x <- 1", rawToChar(collate(f_bom)))

    ## enc = "UTF-8" strips BOM

    !has_bom(collate(f_bom, "UTF-8"))

    grepl("x <- 1", rawToChar(collate(f_bom, "UTF-8")))

    ## enc = "UTF-8": output is exactly 3 bytes shorter

    length(collate(f_bom, "UTF-8")) == length(collate(f_bom)) - 3L

    ## no-BOM file copied fully

    grepl("y <- 2", rawToChar(collate(f_plain, "UTF-8")))

    ## multiple files, mixed BOM

    grepl("x <- 1", rawToChar(collate(c(f_bom, f_plain), "UTF-8")))

    grepl("y <- 2", rawToChar(collate(c(f_bom, f_plain), "UTF-8")))

    !has_bom(collate(c(f_bom, f_plain), "UTF-8"))

    ## BOM-only file: stripped, only #line directive remains

    !has_bom(collate(f_bomonly, "UTF-8"))

    ## short file (< 3 bytes): fully copied

    grepl("z", rawToChar(collate(f_short, "UTF-8")))

})

unlink(c(f_bom, f_plain, f_bomonly, f_short))