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Add strbuf_trunc() primitive, fix bug in strbuf_substr()

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This commit is contained in:
Andrew Bettison 2012-07-10 19:36:25 +09:30
parent 7c2090e61c
commit 2c1c44c4fe
2 changed files with 45 additions and 1 deletions
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18
strbuf.c
View File

@ -98,7 +98,7 @@ char *strbuf_substr(const_strbuf sb, int offset)
{
char *s;
if (offset < 0) {
s = sb->end + offset;
s = (sb->current < sb->end ? sb->current : sb->end) + offset;
if (s < sb->start)
s = sb->start;
} else {
@ -108,3 +108,19 @@ char *strbuf_substr(const_strbuf sb, int offset)
}
return s;
}
strbuf strbuf_trunc(strbuf sb, int offset)
{
char *s;
if (offset < 0) {
s = (sb->current < sb->end ? sb->current : sb->end) + offset;
if (s < sb->start)
s = sb->start;
} else {
s = sb->start + offset;
if (s > sb->end)
s = sb->end;
}
sb->current = s;
return sb;
}

28
strbuf.h
View File

@ -311,6 +311,34 @@ __STRBUF_INLINE char *strbuf_str(const_strbuf sb) {
char *strbuf_substr(const_strbuf sb, int offset);
/** Truncate the string in the strbuf to a given offset. If the offset is
* negative, then it is taken from the end of the string, ie, the length of the
* string is added to it. If the string is shorter than the given offset, then
* it is unchanged. Otherwise, a terminating nul char is written at the offset
* and the string's length truncated accordingly. Return a pointer to the
* strbuf so that operations can be chained in a single line.
*
* After the operation:
* len = strbuf_len(sb);
* strbuf_trunc(sb, off);
* the following invariants hold:
* where len <= off, sb is unchanged;
* where 0 <= off < len:
* strbuf_count(sb) == off
* strbuf_len(sb) == off
* where -len <= off < 0:
* strbuf_count(sb) == len + off
* strbuf_len(sb) == len + off
* where off < -len:
* strbuf_count(sb) == 0
* strbuf_len(sb) == 0
* strbuf_str(sb)[0] == '\0'
*
* @author Andrew Bettison <andrew@servalproject.com>
*/
strbuf strbuf_trunc(strbuf sb, int offset);
/** Return true if the given strbuf is "empty", ie, not modified since being
* initialised to STRUCT_STRBUF_EMPTY or with strbuf_init(sb, NULL, 0);
*