close #67: add a function get_input() to get the input file path to f…

…use()

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: litedown
 Type: Package
 Title: A Lightweight Version of R Markdown
-Version: 0.5.6
+Version: 0.5.7
 Authors@R: c(
     person("Yihui", "Xie", role = c("aut", "cre"), email = "[email protected]", comment = c(ORCID = "0000-0003-0645-5666", URL = "https://yihui.org")),
     person("Tim", "Taylor", role = "ctb", comment = c(ORCID = "0000-0002-8587-7113")),

NAMESPACE

@@ -12,6 +12,7 @@ export(fuse)
 export(fuse_book)
 export(fuse_env)
 export(fuse_site)
+export(get_input)
 export(html_format)
 export(latex_format)
 export(mark)

NEWS.md

@@ -1,5 +1,7 @@
 # CHANGES IN litedown VERSION 0.6
 
+- Added a function `get_input()` to get the input file path to `fuse()` (thanks, @MichaelChirico, #67).
+
 - Fixed a bug that `fuse()` fails to print the error location when the whole input document consists of a single chunk that throws an error (thanks, @kevinushey, yihui/knitr#2387).
 
 # CHANGES IN litedown VERSION 0.5

R/fuse.R

@@ -341,12 +341,21 @@ convert_knitr = function(input) {
   write_utf8(x, input)
 }
 
+#' Get the input file path of `fuse()`
+#'
+#' A helper function to return the input file path of [fuse()] when called
+#' inside a code chunk.
+#' @return A character string, or `NULL` if the input is not a file (e.g., when
+#'   using the `text` argument of `fuse()`).
+#' @export
+get_input = function() .env$input
+
 # return a string to indicate the error location
 get_loc = function(label) {
   l = .env$source_pos; n = length(l)
   if (n == 4) l = sprintf('#%d:%d-%d:%d', l[1], l[2], l[3], l[4])  # row1:col1-row2:col2
   if (n == 2) l = sprintf('#%d-%d', l[1], l[2])  # row1-row2
-  paste0(.env$input, l, if (label != '') paste0(' [', label, ']'))
+  paste0(.env$input2 %|% .env$input, l, if (label != '') paste0(' [', label, ']'))
 }
 
 # save line numbers in .env to be used in error messages
@@ -564,7 +573,7 @@ fiss = function(input, output = '.R', text = NULL) {
 # add ANSI link on input path if supported
 ansi_link = function(x) {
   if (length(x) && isTRUE(as.logical(Sys.getenv('RSTUDIO_CLI_HYPERLINKS'))))
-    .env$input = sprintf(
+    .env$input2 = sprintf(
       '\033]8;%s;file://%s\a%s\033]8;;\a', link_pos(), normalize_path(x), x
     )
 }