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| author | Eli Zaretskii <eliz@gnu.org> | 2016-08-18 17:23:22 +0300 |
|---|---|---|
| committer | Eli Zaretskii <eliz@gnu.org> | 2016-08-18 17:23:22 +0300 |
| commit | 37d4723f73998ecbf30e9f655026422b0e2017a7 (patch) | |
| tree | 7c79b25118da4ccbd46c635987d7fb9003e80803 | |
| parent | 5ccd59339dbde1d428141cd3eb120d4e6d316abf (diff) | |
| download | emacs-37d4723f73998ecbf30e9f655026422b0e2017a7.tar.gz | |
Improve commentary in src/character.h
* src/character.h (BYTES_BY_CHAR_HEAD, MULTIBYTE_LENGTH)
(MULTIBYTE_LENGTH_NO_CHECK, STRING_CHAR_AND_LENGTH): Remove stale
info from commentary and improve it.
| -rw-r--r-- | src/character.h | 20 |
1 files changed, 8 insertions, 12 deletions
diff --git a/src/character.h b/src/character.h index bc3e1557844..d4b6c73cd92 100644 --- a/src/character.h +++ b/src/character.h @@ -237,7 +237,8 @@ enum #define CHAR_HEAD_P(byte) (((byte) & 0xC0) != 0x80) /* How many bytes a character that starts with BYTE occupies in a - multibyte form. */ + multibyte form. Unlike MULTIBYTE_LENGTH below, this macro does not + validate the multibyte form, but looks only at its first byte. */ #define BYTES_BY_CHAR_HEAD(byte) \ (!((byte) & 0x80) ? 1 \ : !((byte) & 0x20) ? 2 \ @@ -247,7 +248,9 @@ enum /* The byte length of multibyte form at unibyte string P ending at - PEND. If STR doesn't point to a valid multibyte form, return 0. */ + PEND. If the string doesn't point to a valid multibyte form, + return 0. Unlike BYTES_BY_CHAR_HEAD, this macro validates the + multibyte form. */ #define MULTIBYTE_LENGTH(p, pend) \ (p >= pend ? 0 \ @@ -263,7 +266,8 @@ enum : 0) -/* Like MULTIBYTE_LENGTH, but don't check the ending address. */ +/* Like MULTIBYTE_LENGTH, but don't check the ending address. The + multibyte form is still validated, unlike BYTES_BY_CHAR_HEAD. */ #define MULTIBYTE_LENGTH_NO_CHECK(p) \ (!((p)[0] & 0x80) ? 1 \ @@ -324,15 +328,7 @@ enum /* Like STRING_CHAR, but set ACTUAL_LEN to the length of multibyte - form. - - Note: This macro returns the actual length of the character's - multibyte sequence as it is stored in a buffer or string. The - character it returns might have a different codepoint that has a - different multibyte sequence of a different length, due to possible - unification of CJK characters inside string_char. Therefore do NOT - assume that the length returned by this macro is identical to the - length of the multibyte sequence of the character it returns. */ + form. */ #define STRING_CHAR_AND_LENGTH(p, actual_len) \ (!((p)[0] & 0x80) \ |