Source Map

Builder can add line number comments to your output files with the -sourcemap flag. This helps trace errors in processed R files back to their original source line numbers.

Usage

builder -input srcr -output R -sourcemap

How It Works

When enabled, Builder appends a # filename:N comment to the end of each line, indicating the source file and original line number.

Example

Input (srcr/utils.R):

#> define API_URL "https://api.example.com"

#> ifdef DEBUG
log_debug <- function(msg) {
  cat(msg, "\n")
}
#> endif

fetch_data <- function() {
  url <- API_URL
  httr::GET(url)
}

Output (R/utils.R):

log_debug <- function(msg) { # srcr/utils.R:4
  cat(msg, "\n") # srcr/utils.R:5
} # srcr/utils.R:6

fetch_data <- function() { # srcr/utils.R:9
  url <- "https://api.example.com" # srcr/utils.R:10
  httr::GET(url) # srcr/utils.R:11
} # srcr/utils.R:12

Notice how:

• The #> define and #> ifdef/#> endif directives are removed from output
• Output has only 8 lines, but annotations reference the original source lines (4-6, 9-12)
• Each comment shows the source file and line number (e.g., # srcr/utils.R:5)

Skipped Lines

The following lines do not receive sourcemap comments:

• Empty or whitespace-only lines
• Lines containing # (comments)