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Fixes for string-set!

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Handle setting of a char to one that is represented using fewer bytes.
This commit is contained in:
Justin Ethier 2017-11-08 14:55:57 +00:00
parent 61a18d8fb3
commit 0f4a7b30c1
1 changed files with 24 additions and 24 deletions
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48
runtime.c
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@ -2139,39 +2139,35 @@ object Cyc_string_set(void *data, object str, object k, object chr)
Cyc_check_bounds(data, "string-set!", len, idx);
// Take fast path if all chars are just 1 byte
if (string_num_cp(str) == string_len(str) && buf_len == 1) {
// Take fast path if all chars are just 1 byte
raw[idx] = obj_obj2char(chr);
} else {
fprintf(stderr, "DEBUG %s, num_cp = %d, len = %d\n", raw, string_num_cp(str), len);
// TODO: utf8 support
// find codepoint at k, figure out how many bytes it is,
// allocate a new string (start) + chr + (end)
// or don't allocate if chr uses as many or fewer bytes
// than the codepoint it is replacing
// Slower path for UTF-8, need to handle replacement differently
// depending upon how the new char affects length of the string
char *tmp = raw, *this_cp = raw;
char_type codepoint;
uint32_t state = 0;
int i = 0, count, bytes = 0;
int i = 0, count, prev_cp_bytes = 0, cp_idx;
for (count = 0; *tmp; ++tmp){
bytes++;
prev_cp_bytes++;
if (!Cyc_utf8_decode(&state, &codepoint, (uint8_t)*tmp)){
if (count == idx) {
break;
}
this_cp = tmp + 1;
count += 1;
bytes = 0;
prev_cp_bytes = 0;
}
i++;
}
cp_idx = i;
if (state != CYC_UTF8_ACCEPT) {
Cyc_rt_raise2(data, "string-set! - invalid character at index", k);
}
// TODO: perform actual mutation
// Perform actual mutation
//
// Now we know length of start (both in codepoints and bytes),
// and we know the codepoint to be replaced. by calculating its length
@ -2179,22 +2175,26 @@ fprintf(stderr, "DEBUG %s, num_cp = %d, len = %d\n", raw, string_num_cp(str), le
// figure out how many remaining bytes/codepoints are in end
//
// 3 cases:
// - buf_len = bytes, just straight replace
if (buf_len == bytes) {
// - 1) buf_len = prev_cp_bytes, just straight replace
if (buf_len == prev_cp_bytes) {
for (i = 0; i < buf_len; i++) {
this_cp[i] = buf[i];
}
}
// - buf_len > bytes, will need to allocate more memory (!!)
// - buf_len < bytes, just replace, but pad with NULL chars.
// in this case need to ensure string_len is not
// reduced because original value still matters for GC purposes
//else if (buf_len < bytes) {
// for (i = 0; i < buf_len; i++) {
// this_cp[i] = buf[i];
// }
// TODO: memcpy remaining string, ensure trailing null is setup correctly, consolidate with above??
//}
// - 2) buf_len < prev_cp_bytes, replace and shift chars down
else if (buf_len < prev_cp_bytes) {
// Replace code point with shorter one
for (i = 0; i < buf_len; i++) {
this_cp[i] = buf[i];
}
// Move string down to eliminate unneeded chars
memmove(this_cp + buf_len, this_cp + prev_cp_bytes, len - cp_idx);
// Null terminate the shorter string.
// Ensure string_len is not reduced because original
// value still matters for GC purposes
raw[len - (prev_cp_bytes - buf_len)] = '\0';
}
// - 3) TODO: buf_len > prev_cp_bytes, will need to allocate more memory (!!)
else {
Cyc_rt_raise2(data, "string-set! - unable to modify character", chr);
}