StrPatchFmt
Description
Patch existing bytes in out starting at offset. The formatted content must fit within the current StrLen(out); the buffer is not grown. Useful for back-patching placeholder fields after later data has been computed.
Success
Bytes [offset, offset + written) of out are replaced; returns true.
Failure
Returns false if the formatted output would extend past StrLen(out). out is left unchanged.
Usage example (Cross-references)
Usage examples (Cross-references)
- In
Io.c:504:
if (offset > StrLen(o) || StrLen(&tmp) > StrLen(o) - offset) {
LOG_ERROR(
"StrPatchFmt: write of {} bytes at offset {} exceeds str length {}",
StrLen(&tmp),
offset,- In
Write.c:700:
StrAppendFmt(&s, "AAAAAAAA");
size before_length = StrLen(&s);
bool ok = StrPatchFmt(&s, 2, "{}", LVAL(1234));
ok = ok && StrLen(&s) == before_length;
ok = ok && StrBegin(&s)[0] == 'A' && StrBegin(&s)[1] == 'A';- In
Write.c:707:
// Patch that would extend past the end must fail.
ok = ok && !StrPatchFmt(&s, 6, "{}", LVAL(9999));
ok = ok && StrLen(&s) == before_length;
ok = ok && StrBegin(&s)[6] == 'A' && StrBegin(&s)[7] == 'A';- In
Write.c:3754:
// "AB{" pushes "AB" into the scratch then hits an unclosed spec ->
// str_append_fmt returns false.
bool r = StrPatchFmt(&o, 0, "AB{");
bool ok = (r == false) && (ZstrCompare(StrBegin(&o), "-----") == 0);- In
Write.c:3770:
Str o = StrInitFromZstr("hello", &alloc);
bool r = StrPatchFmt(&o, StrLen(&o), ""); // offset == length, empty render
bool ok = (r == true) && (ZstrCompare(StrBegin(&o), "hello") == 0);- In
Write.c:3786:
Str o = StrInitFromZstr("-----", &alloc); // length 5
bool r = StrPatchFmt(&o, 0, "12345"); // renders exactly 5 chars
bool ok = (r == true) && (ZstrCompare(StrBegin(&o), "12345") == 0);- In
Write.c:4119:
StrAppendFmt(&s, "AAAAAAAA");
size before = StrLen(&s);
ok = ok && StrPatchFmt(&s, 2, "{}", LVAL(1234));
ok = ok && (StrLen(&s) == before);
ok = ok && StrBegin(&s)[2] == '1' && StrBegin(&s)[5] == '4';
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