Implement default help-echo for mode line.

[bpt/emacs.git] / src / buffer.h

diff --git a/src/buffer.h b/src/buffer.h
index e2d4b55..3aa4b11 100644 (file)
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -1,6 +1,6 @@
 /* Header file for the buffer manipulation primitives.
 
-Copyright (C) 1985-1986, 1993-1995, 1997-2011
+Copyright (C) 1985-1986, 1993-1995, 1997-2012
                  Free Software Foundation, Inc.
 
 This file is part of GNU Emacs.
@@ -343,7 +343,8 @@ while (0)
  - (ptr - (current_buffer)->text->beg <= GPT_BYTE - BEG_BYTE ? 0 : GAP_SIZE) \
  + BEG_BYTE)
 
-/* Return character at byte position POS.  */
+/* Return character at byte position POS.  See the caveat WARNING for
+   FETCH_MULTIBYTE_CHAR below.  */
 
 #define FETCH_CHAR(pos)                                        \
   (!NILP (BVAR (current_buffer, enable_multibyte_characters))  \
@@ -359,7 +360,17 @@ extern unsigned char *_fetch_multibyte_char_p;
 
 /* Return character code of multi-byte form at byte position POS.  If POS
    doesn't point the head of valid multi-byte form, only the byte at
-   POS is returned.  No range checking.  */
+   POS is returned.  No range checking.
+
+   WARNING: The character returned by this macro could be "unified"
+   inside STRING_CHAR, if the original character in the buffer belongs
+   to one of the Private Use Areas (PUAs) of codepoints that Emacs
+   uses to support non-unified CJK characters.  If that happens,
+   CHAR_BYTES will return a value that is different from the length of
+   the original multibyte sequence stored in the buffer.  Therefore,
+   do _not_ use FETCH_MULTIBYTE_CHAR if you need to advance through
+   the buffer to the next character after fetching this one.  Instead,
+   use either FETCH_CHAR_ADVANCE or STRING_CHAR_AND_LENGTH.  */
 
 #define FETCH_MULTIBYTE_CHAR(pos)                                      \
   (_fetch_multibyte_char_p = (((pos) >= GPT_BYTE ? GAP_SIZE : 0)       \
@@ -901,6 +912,7 @@ extern void validate_region (Lisp_Object *, Lisp_Object *);
 extern void set_buffer_internal (struct buffer *);
 extern void set_buffer_internal_1 (struct buffer *);
 extern void set_buffer_temp (struct buffer *);
+extern Lisp_Object buffer_local_value_1 (Lisp_Object, Lisp_Object);
 extern void record_buffer (Lisp_Object);
 extern void buffer_slot_type_mismatch (Lisp_Object, int) NO_RETURN;
 extern void fix_overlays_before (struct buffer *, ptrdiff_t, ptrdiff_t);