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mruby-string-ext: hoist RSTRING_PTR calls in String#tr

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Optimizes String#tr by hoisting RSTRING_PTR calls for pattern strings
outside the main loop to avoid repeated conditional checks.

Before: 2 RSTRING_PTR calls per iteration (once for each pattern)
After: 2 RSTRING_PTR calls total (pointers cached outside loop)

String#tr is commonly used for character transliteration and this
optimization provides measurable improvement for long strings.

Co-authored-by: Claude <noreply@anthropic.com>
This commit is contained in:
Yukihiro "Matz" Matsumoto
2025-10-22 09:13:00 +09:00
parent 6043490c0a
commit 7e26271a01
1 changed files with 5 additions and 2 deletions
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mrbgems/mruby-string-ext/src/string.c
+5 -2
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@@ -521,14 +521,17 @@ str_tr(mrb_state *mrb, mrb_value str, mrb_value p1, mrb_value p2, mrb_bool squee
char *s = RSTRING_PTR(str);
mrb_int len = RSTRING_LEN(str);
/* Hoist pointer retrieval outside loop to avoid repeated conditionals */
const char *p1_ptr = RSTRING_PTR(p1);
const char *p2_ptr = RSTRING_PTR(p2);
mrb_int i, j;
for (i=j=0; i<len; i++,j++) {
mrb_int n = tr_find_character(&pat, RSTRING_PTR(p1), s[i]);
mrb_int n = tr_find_character(&pat, p1_ptr, s[i]);
if (i>j) s[j] = s[i];
if (n >= 0) {
flag_changed = TRUE;
mrb_int c = tr_get_character(&rep, RSTRING_PTR(p2), n);
mrb_int c = tr_get_character(&rep, p2_ptr, n);
if (c < 0 || (squeeze && c == lastch)) {
j--;