From 86697ca7b47ee826598c30948549651e662f09e3 Mon Sep 17 00:00:00 2001
From: Yukihiro Matsumoto <matz@ruby-lang.org>
Date: Thu, 31 May 2012 16:14:11 +0900
Subject: reimplement String#downcase

---
 src/string.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

(limited to 'src/string.c')

diff --git a/src/string.c b/src/string.c
index a9e0fca13..c9fac896d 100644
--- a/src/string.c
+++ b/src/string.c
@@ -927,6 +927,20 @@ mrb_str_chop(mrb_state *mrb, mrb_value self)
 static mrb_value
 mrb_str_downcase_bang(mrb_state *mrb, mrb_value str)
 {
+  char *s, *send;
+  int modify = 0;
+
+  s = RSTRING_PTR(str);
+  send = RSTRING_END(str);
+  while (s < send) {
+    if (ISUPPER(*s)) {
+      *s = tolower(*s);
+      modify = 1;
+    }
+    s++;
+  }
+
+  if (modify) return str;
   return mrb_nil_value();
 }
 
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