diff options
| -rw-r--r-- | src/coding.c | 27 | ||||
| -rw-r--r-- | test/src/coding-tests.el | 11 |
2 files changed, 37 insertions, 1 deletions
diff --git a/src/coding.c b/src/coding.c index 1049f1b755a..97a6eb949a8 100644 --- a/src/coding.c +++ b/src/coding.c @@ -9471,6 +9471,17 @@ not fully specified.) */) return code_convert_region (start, end, coding_system, destination, 1, 0); } +/* Whether a string only contains chars in the 0..127 range. */ +static bool +string_ascii_p (Lisp_Object str) +{ + ptrdiff_t nbytes = SBYTES (str); + for (ptrdiff_t i = 0; i < nbytes; i++) + if (SREF (str, i) > 127) + return false; + return true; +} + Lisp_Object code_convert_string (Lisp_Object string, Lisp_Object coding_system, Lisp_Object dst_object, bool encodep, bool nocopy, @@ -9502,7 +9513,21 @@ code_convert_string (Lisp_Object string, Lisp_Object coding_system, chars = SCHARS (string); bytes = SBYTES (string); - if (BUFFERP (dst_object)) + if (EQ (dst_object, Qt)) + { + /* Fast path for ASCII-only input and an ASCII-compatible coding: + act as identity. */ + Lisp_Object attrs = CODING_ID_ATTRS (coding.id); + if (! NILP (CODING_ATTR_ASCII_COMPAT (attrs)) + && (STRING_MULTIBYTE (string) + ? (chars == bytes) : string_ascii_p (string))) + return (nocopy + ? string + : (encodep + ? make_unibyte_string (SDATA (string), bytes) + : make_multibyte_string (SDATA (string), bytes, bytes))); + } + else if (BUFFERP (dst_object)) { struct buffer *buf = XBUFFER (dst_object); ptrdiff_t buf_pt = BUF_PT (buf); diff --git a/test/src/coding-tests.el b/test/src/coding-tests.el index 110ff126964..93e6709d442 100644 --- a/test/src/coding-tests.el +++ b/test/src/coding-tests.el @@ -383,6 +383,17 @@ (should-not (eq (encode-coding-string s nil nil) s)) (should (eq (encode-coding-string s nil t) s)))) +(ert-deftest coding-nocopy-ascii () + "Check that the NOCOPY parameter works for ASCII-only strings." + (let* ((uni (apply #'string (number-sequence 0 127))) + (multi (string-to-multibyte uni))) + (dolist (s (list uni multi)) + (dolist (coding '(us-ascii iso-latin-1 utf-8)) + (should-not (eq (decode-coding-string s coding nil) s)) + (should-not (eq (encode-coding-string s coding nil) s)) + (should (eq (decode-coding-string s coding t) s)) + (should (eq (encode-coding-string s coding t) s)))))) + ;; Local Variables: ;; byte-compile-warnings: (not obsolete) ;; End: |