~ruther/guix-local: po: Don't replace newline escapes that are escaped themselves.

e16cfd61f96155ba5d42df4af92c09a39abb3ee4 — Florian Pelz 6 months ago 3bc0cf8

po: Don't replace newline escapes that are escaped themselves.

Otherwise the cookbook is read incorrectly at
msgid ""
"(display (string-append \"Hello \" \"Guix\" \"\\n\"))\n"

This can be seen at the `git diff` when beginning to
run `make download-po`.

* guix/build/po.scm (final-character-escapes?): New procedure.
(interpret-newline-escape): Use it.

Change-Id: I2b036000173b1e282e2aeceffe3491e0917e51ca

patch browse .tar.gz

1 files changed, 12 insertions(+), 2 deletions(-)

M guix/build/po.scm

M guix/build/po.scm => guix/build/po.scm +12 -2

@@ 48,8 48,15 @@
   (and (ignore "\"") (* str-chr) (ignore "\"")
        (? (and (ignore (* whitespace)) content))))
 
+(define (final-character-escapes? str last-index)
+  "Check if STR ends in an incomplete escape sequence, that is ends in an uneven
+number of backslashes.  LAST-INDEX is the index of its last character."
+  (and (>= last-index 0)
+       (eqv? (string-ref str last-index) #\\)
+       (not (final-character-escapes? str (- last-index 1)))))
+
 (define (interpret-newline-escape str)
-  "Replace '\\n' sequences in STR with a newline character."
+  "Replace unescaped '\\n' sequences in STR with a newline character."
   (let loop ((str str)
              (result '()))
     (match (string-contains str "\\n")


@@ 57,7 64,10 @@
       (index
        (let ((prefix (string-take str index)))
          (loop (string-drop str (+ 2 index))
-               (append (list "\n" prefix) result)))))))
+               ;; Only add a newline when the backslash is not escaped itself.
+               (if (final-character-escapes? str (- index 1))
+                   (cons (string-take str (+ 2 index)) result)
+                   (append (list "\n" prefix) result))))))))
 
 (define (parse-tree->assoc parse-tree)
   "Converts a po PARSE-TREE to an association list, where the key is the msgid