This patch tidies up the formatting of string_substr and string_replace,
adds a bunch of comments, and moves a couple of assignments closer to
where the variables are actually used; none of the functionality should
be affected. All tests still pass (including the ones in a previous patch
that nobody's applied yet)
Simon
--- string.c.old Mon Apr 15 21:00:00 2002
+++ string.c Tue Apr 16 17:00:03 2002
@@ -362,7 +362,6 @@
return string_make(interpreter, NULL, 0, src->encoding, 0, src->type);
}
- true_length = (UINTVAL)length;
if (offset < 0) {
true_offset = (UINTVAL)(src->strlen + offset);
}
@@ -371,18 +370,20 @@
internal_exception(SUBSTR_OUT_OF_STRING,
"Cannot take substr outside string");
}
+
+ true_length = (UINTVAL)length;
if (true_length > (src->strlen - true_offset)) {
true_length = (UINTVAL)(src->strlen - true_offset);
}
substart_off = (const char *)src->encoding->skip_forward(src->bufstart,
- true_offset) -
- (char *)src->bufstart;
+ true_offset)
+ - (char *)src->bufstart;
+
subend_off =
- (const char *)src->encoding->skip_forward((char *)src->bufstart +
- substart_off,
- true_length) -
- (char *)src->bufstart;
+ (const char *)src->encoding->skip_forward((char *)src->bufstart
+ + substart_off, true_length)
+ - (char *)src->bufstart;
dest =
string_make(interpreter, NULL, true_length * src->encoding->max_bytes,
@@ -428,37 +429,43 @@
INTVAL diff;
true_offset = (UINTVAL)offset;
- true_length = (UINTVAL)length;
- if(rep->encoding != src->encoding || rep->type != src->type)
- rep = string_transcode(interpreter, rep, src->encoding, src->type, NULL);
+ /* If the offset is negative, then abs(offset) should not be larger
+ * than the length of the string. If it is, then the cast ensures
+ * that true_offset is larger than any possible string length (and
+ * hence will generate an exception in the next statement).
+ */
- /* abs(-offset) may not be > strlen-1 */
if (offset < 0) {
true_offset = (UINTVAL)(src->strlen + offset);
}
- /* Can replace 1 past end of string which is technically outside the string
- * but is same as a concat().
- * Only give exception if caller trys to replace end of string + 2
+ /* Replacing one character past the end of the string has the
+ * same effect as string_concat(); therefore, only throw an
+ * exception if the caller tries to replace two or more characters
+ * past the end of the string
*/
if (true_offset > src->strlen) {
internal_exception(SUBSTR_OUT_OF_STRING,
"Can only replace inside string or index after end of string");
}
+
+ true_length = (UINTVAL)length;
if (true_length > (src->strlen - true_offset)) {
true_length = (UINTVAL)(src->strlen - true_offset);
}
- /* Save the substring that is replaced for the return value */
- substart_off = (char *)src->encoding->skip_forward(src->bufstart,
- true_offset) -
- (char *)src->bufstart;
+ /* Construct and save the substring that is replaced; this will be
+ * the function return value
+ */
+ substart_off = (const char *)src->encoding->skip_forward(src->bufstart,
+ true_offset)
+ - (char *)src->bufstart;
+
subend_off =
- (char *)src->encoding->skip_forward((char *)src->bufstart +
- substart_off,
- true_length) -
- (char *)src->bufstart;
+ (const char *)src->encoding->skip_forward((char *)src->bufstart
+ + substart_off, true_length)
+ - (char *)src->bufstart;
if (subend_off < substart_off) {
internal_exception(SUBSTR_OUT_OF_STRING,
@@ -479,43 +486,54 @@
}
/* Now do the replacement */
+
+ if(rep->encoding != src->encoding || rep->type != src->type)
+ rep =
+ string_transcode(interpreter, rep, src->encoding, src->type, NULL);
/*
- * If the replacement string fits inside the original substring
+ * If the replacement string fits inside the original substring,
+ * or there's sufficient space left in the string buffer, then
* don't create a new string, just pack it.
*/
+
diff = (subend_off - substart_off) - rep->bufused;
if(diff >= 0
|| ((INTVAL)src->bufused - (INTVAL)src->buflen) <= diff) {
-
+
if(diff != 0) {
mem_sys_memmove((char*)src->bufstart + substart_off + rep->bufused,
- (char*)src->bufstart + subend_off,
- src->buflen - (subend_off - diff));
+ (char*)src->bufstart + subend_off,
+ src->buflen - (subend_off - diff));
+
src->bufused -= diff;
}
mem_sys_memcopy((char*)src->bufstart + substart_off,
- rep->bufstart, rep->bufused);
+ rep->bufstart, rep->bufused);
+
if(diff != 0)
(void)string_compute_strlen(src);
}
/*
- * Replacement is larger than avail buffer, grow the string
+ * The replacement is larger than the space available, so grow the string
*/
else {
/* diff is negative here, make it positive */
diff = -(diff);
+
string_grow(interpreter, src, diff);
- /* Move the end of old string that isn't replaced to new offset first */
+ /* Move the end of the old string that isn't replaced to its new
+ * offset first */
mem_sys_memmove((char*)src->bufstart + subend_off + diff,
- (char*)src->bufstart + subend_off,
- src->buflen - subend_off);
+ (char*)src->bufstart + subend_off,
+ src->buflen - subend_off);
+
/* Copy the replacement in */
- mem_sys_memcopy((char *)src->bufstart + substart_off, rep->bufstart,
- rep->bufused);
+ mem_sys_memcopy((char *)src->bufstart + substart_off,
+ rep->bufstart, rep->bufused);
src->bufused += diff;
(void)string_compute_strlen(src);
}
