From 62505d51cc9c0600677acdae734475cda7095103 Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby-lang.org>
Date: Sat, 15 Mar 2014 15:53:12 +0900
Subject: calc hash value directly for strings, symbols and numbers

---
 src/etc.c  |  8 ++++----
 src/hash.c | 37 +++++++++++++++++++++++++++++++++----
 2 files changed, 37 insertions(+), 8 deletions(-)

(limited to 'src')

diff --git a/src/etc.c b/src/etc.c
index cf7547c2d..8398aeebd 100644
--- a/src/etc.c
+++ b/src/etc.c
@@ -86,8 +86,8 @@ mrb_obj_to_sym(mrb_state *mrb, mrb_value name)
   return id;
 }
 
-static mrb_int
-float_id(mrb_float f)
+mrb_int
+mrb_float_id(mrb_float f)
 {
   const char *p = (const char*)&f;
   int len = sizeof(f);
@@ -123,9 +123,9 @@ mrb_obj_id(mrb_value obj)
   case  MRB_TT_SYMBOL:
     return MakeID(mrb_symbol(obj));
   case  MRB_TT_FIXNUM:
-    return MakeID2(float_id((mrb_float)mrb_fixnum(obj)), MRB_TT_FLOAT);
+    return MakeID2(mrb_float_id((mrb_float)mrb_fixnum(obj)), MRB_TT_FLOAT);
   case  MRB_TT_FLOAT:
-    return MakeID(float_id(mrb_float(obj)));
+    return MakeID(mrb_float_id(mrb_float(obj)));
   case  MRB_TT_STRING:
   case  MRB_TT_OBJECT:
   case  MRB_TT_CLASS:
diff --git a/src/hash.c b/src/hash.c
index 86ad4c63d..ed71d6ee2 100644
--- a/src/hash.c
+++ b/src/hash.c
@@ -12,14 +12,43 @@
 #include "mruby/string.h"
 #include "mruby/variable.h"
 
+/* a function to get hash value of a float number */
+mrb_int mrb_float_id(mrb_float f);
+
 static inline khint_t
 mrb_hash_ht_hash_func(mrb_state *mrb, mrb_value key)
 {
-  khint_t h = (khint_t)mrb_type(key) << 24;
-  mrb_value h2;
+  enum mrb_vtype t = mrb_type(key);
+  mrb_value hv;
+  const char *p;
+  mrb_int i, len;
+  khint_t h;
+
+  switch (t) {
+  case MRB_TT_STRING:
+    p = RSTRING_PTR(key);
+    len = RSTRING_LEN(key);
+    break;
+
+  case MRB_TT_SYMBOL:
+    p = mrb_sym2name_len(mrb, mrb_symbol(key), &len);
+    break;
+
+  case MRB_TT_FIXNUM:
+    return (khint_t)mrb_float_id((mrb_float)mrb_fixnum(key));
+
+  case MRB_TT_FLOAT:
+    return (khint_t)mrb_float_id(mrb_float(key));
+
+  default:
+    hv = mrb_funcall(mrb, key, "hash", 0);
+    return (khint_t)t ^ mrb_fixnum(hv);
+  }
 
-  h2 = mrb_funcall(mrb, key, "hash", 0);
-  h ^= h2.value.i;
+  h = 0;
+  for (i=0; i<len; i++) {
+    h = (h << 5) - h + *p++;
+  }
   return h;
 }
 
-- 
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