Read all text files and concatenate their content

Read files one by one, and optionally add text before/after the content. Then combine all content into one character vector.

read_all(files, before = function(f, x) NULL, after = function(f, x) NULL)

Arguments

files

A vector of file paths.

before, after

A function that takes one file path and its content as the input and returns values to be added before or after the content of the file. Alternatively, they can be constant values to be added.

Value

A character vector.

Examples

# two files in this package
fs = system.file("scripts", c("call-fun.R", "child-pids.sh"), package = "xfun")
xfun::read_all(fs)
#> # This script is executed via the command line `Rscript call-fun.R arg1 arg2
#> # arg3`, where arg1 is a path to an .rds file, which contains the function and
#> # its arguments saved as a list; arg2 is a path to an .rds file to which the
#> # returned value of the function call is saved; arg3 saves the error message.
#> 
#> local({
#>   if (length(a <- commandArgs(TRUE)) != 3)
#>     stop('The number of arguments passed to Rscript should be 3.')
#>   # save the error message on exit if an error occurred
#>   on.exit(if (!file.exists(a[2])) saveRDS(geterrmessage(), a[3]))
#>   x = readRDS(a[1])  # list(fun, args)
#>   f = x[[1]]
#>   if (is.character(f)) f = eval(parse(text = f), envir = globalenv())
#>   r = do.call(f, x[[2]], envir = globalenv())
#>   saveRDS(r, a[2])
#> })
#> # given a PID, output all its child PIDs recursively
#> list_children() {
#>   for j in $(pgrep -P $1); do
#>     echo $j
#>     echo $(list_children $j)
#>   done
#> }
#> 
#> for i in $@; do
#>   list_children $i
#> done

# add file paths before file content and an empty line after content
xfun::read_all(fs, before = function(f) paste("#-----", f, "-----"), after = "")
#> #----- /tmp/RtmplGg3Jy/temp_libpath39927d15f364fe/xfun/scripts/call-fun.R -----
#> # This script is executed via the command line `Rscript call-fun.R arg1 arg2
#> # arg3`, where arg1 is a path to an .rds file, which contains the function and
#> # its arguments saved as a list; arg2 is a path to an .rds file to which the
#> # returned value of the function call is saved; arg3 saves the error message.
#> 
#> local({
#>   if (length(a <- commandArgs(TRUE)) != 3)
#>     stop('The number of arguments passed to Rscript should be 3.')
#>   # save the error message on exit if an error occurred
#>   on.exit(if (!file.exists(a[2])) saveRDS(geterrmessage(), a[3]))
#>   x = readRDS(a[1])  # list(fun, args)
#>   f = x[[1]]
#>   if (is.character(f)) f = eval(parse(text = f), envir = globalenv())
#>   r = do.call(f, x[[2]], envir = globalenv())
#>   saveRDS(r, a[2])
#> })
#> 
#> #----- /tmp/RtmplGg3Jy/temp_libpath39927d15f364fe/xfun/scripts/child-pids.sh -----
#> # given a PID, output all its child PIDs recursively
#> list_children() {
#>   for j in $(pgrep -P $1); do
#>     echo $j
#>     echo $(list_children $j)
#>   done
#> }
#> 
#> for i in $@; do
#>   list_children $i
#> done
#> 

# add constants
xfun::read_all(fs, before = "/*", after = c("*/", ""))
#> /*
#> # This script is executed via the command line `Rscript call-fun.R arg1 arg2
#> # arg3`, where arg1 is a path to an .rds file, which contains the function and
#> # its arguments saved as a list; arg2 is a path to an .rds file to which the
#> # returned value of the function call is saved; arg3 saves the error message.
#> 
#> local({
#>   if (length(a <- commandArgs(TRUE)) != 3)
#>     stop('The number of arguments passed to Rscript should be 3.')
#>   # save the error message on exit if an error occurred
#>   on.exit(if (!file.exists(a[2])) saveRDS(geterrmessage(), a[3]))
#>   x = readRDS(a[1])  # list(fun, args)
#>   f = x[[1]]
#>   if (is.character(f)) f = eval(parse(text = f), envir = globalenv())
#>   r = do.call(f, x[[2]], envir = globalenv())
#>   saveRDS(r, a[2])
#> })
#> */
#> 
#> /*
#> # given a PID, output all its child PIDs recursively
#> list_children() {
#>   for j in $(pgrep -P $1); do
#>     echo $j
#>     echo $(list_children $j)
#>   done
#> }
#> 
#> for i in $@; do
#>   list_children $i
#> done
#> */
#>