R/mod_c_file.R

In edwindj/rvee: Recreational v Programming for R

C_FILE <-
'/* Automatically generated with V <https://vlang.io>
*  using R package: `rvee`.
*  rvee version: {{version}}
*  source: `./v/rv_export.v`
*
*  note: builtin functions "panic", "exit", "print", "println", "eprint" and
*        "eprintln" are adjusted and redirect to R.
*/
'

#' modify c file so it redirects to R constructs when printing and erroring.
#' @keywords internal
mod_c_file <- function(c_file, pkg){
  c_code <- readLines(c_file)

  data <- list(version = utils::packageVersion("rvee"))
  preamble <- whisker::whisker.render(C_FILE, data = data)

  # change printf into Rprintf
  c_code <- gsub("\\bprintf\\b", "Rprintf", c_code)

  # redirect v_panic
  body_begin <- grep("\\bvoid _v_panic\\(", c_code)[2]
  end_function <- grep("^\\}", c_code)
  body_end <- end_function[end_function>body_begin][1]
  c_code <- c( c_code[1:body_begin]
             , '\tRf_error("%s", s.str);'
             , c_code[body_end:length(c_code)]
             )

  # redirect exit
  c_code <- gsub("\\bexit\\((\\w+)\\)", 'Rf_error("exit code: %d", \\1)', c_code)

  # redirect print
  body_begin <- grep("\\bvoid print\\(", c_code)[2]
  end_function <- grep("^\\}", c_code)
  body_end <- end_function[end_function>body_begin][1]
  c_code <- c( c_code[1:body_begin]
             , '\tRprintf("%s", s.str);'
             , c_code[body_end:length(c_code)]
             )

    # redirect println
  body_begin <- grep("\\bvoid println", c_code)[2]
  end_function <- grep("^\\}", c_code)
  body_end <- end_function[end_function>body_begin][1]
  c_code <- c( c_code[1:body_begin]
             , '\tRprintf("%s\\n", s.str);'
             , c_code[body_end:length(c_code)]
             )

  # redirect eprint
  body_begin <- grep("\\bvoid eprint\\(", c_code)[2]
  end_function <- grep("^\\}", c_code)
  body_end <- end_function[end_function>body_begin][1]
  c_code <- c( c_code[1:body_begin]
             , '\tREprintf("%s", s.str);'
             , c_code[body_end:length(c_code)]
             )

    # redirect eprintln
  body_begin <- grep("\\bvoid eprintln\\(", c_code)[2]
  end_function <- grep("^\\}", c_code)
  body_end <- end_function[end_function>body_begin][1]
  c_code <- c( c_code[1:body_begin]
             , '\tREprintf("%s\\n", s.str);'
             , c_code[body_end:length(c_code)]
             )

  c_code <- c(preamble, c_code)
  writeLines(c_code, c_file)
}