From f13c0269f45a6822fd64fe90042677eaf0dd1cb3 Mon Sep 17 00:00:00 2001
From: Chris Griego <cgriego@gmail.com>
Date: Mon, 21 Jan 2013 17:46:33 -0600
Subject: [PATCH] Optimize BSON::ObjectId.from_string and BSON::ObjectID.legal?
 via C extensions.

---
 ext/cbson/cbson.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/ext/cbson/cbson.c b/ext/cbson/cbson.c
index a4665ba1b1..aa383d14cd 100644
--- a/ext/cbson/cbson.c
+++ b/ext/cbson/cbson.c
@@ -93,6 +93,7 @@ static VALUE OrderedHash;
 static VALUE InvalidKeyName;
 static VALUE InvalidStringEncoding;
 static VALUE InvalidDocument;
+static VALUE InvalidObjectId;
 static VALUE DigestMD5;
 static VALUE RB_HASH;
 
@@ -924,6 +925,64 @@ static VALUE method_deserialize(VALUE self, VALUE bson) {
     return elements_to_hash(buffer, remaining);
 }
 
+static int legal_objectid_str(VALUE str) {
+    int i;
+
+    if (TYPE(str) != T_STRING) {
+        return 0;
+    }
+
+    if (RSTRING_LEN(str) != 24) {
+        return 0;
+    }
+
+    for(i = 0; i < 24; i++) {
+        char c = RSTRING_PTR(str)[i];
+
+        if (!((c >= '0' && c <= '9') || (c >= 'A' && c <= 'F') || (c >= 'a' && c <= 'f'))) {
+            return 0;
+        }
+    }
+
+    return 1;
+}
+
+static VALUE objectid_legal(VALUE self, VALUE str)
+{
+    if (legal_objectid_str(str))
+        return Qtrue;
+    return Qfalse;
+}
+
+static char hexbyte( char hex ) {
+    if (hex >= '0' && hex <= '9')
+        return (hex - '0');
+    else if (hex >= 'A' && hex <= 'F')
+        return (hex - 'A' + 10);
+    else if (hex >= 'a' && hex <= 'f')
+        return (hex - 'a' + 10);
+    else
+        return 0x0;
+}
+
+static VALUE objectid_from_string(VALUE self, VALUE str)
+{
+    VALUE oid;
+    int i;
+
+    if (!legal_objectid_str(str)) {
+        rb_raise(InvalidObjectId, "illegal ObjectId format: %s", RSTRING_PTR(str));
+    }
+
+    oid = rb_ary_new2(12);
+
+    for(i = 0; i < 12; i++) {
+        rb_ary_store(oid, i, INT2FIX( (unsigned)(hexbyte( RSTRING_PTR(str)[2*i] ) << 4 ) | hexbyte( RSTRING_PTR(str)[2*i + 1] )));
+    }
+
+    return rb_class_new_instance(1, &oid, ObjectId);
+}
+
 static VALUE objectid_generate(int argc, VALUE* args, VALUE self)
 {
     VALUE oid;
@@ -1002,6 +1061,7 @@ void Init_cbson() {
     InvalidKeyName = rb_const_get(bson, rb_intern("InvalidKeyName"));
     InvalidStringEncoding = rb_const_get(bson, rb_intern("InvalidStringEncoding"));
     InvalidDocument = rb_const_get(bson, rb_intern("InvalidDocument"));
+    InvalidObjectId = rb_const_get(bson, rb_intern("InvalidObjectId"));
     rb_require("bson/ordered_hash");
     OrderedHash = rb_const_get(bson, rb_intern("OrderedHash"));
     RB_HASH = rb_const_get(bson, rb_intern("Hash"));
@@ -1018,6 +1078,8 @@ void Init_cbson() {
     Digest = rb_const_get(rb_cObject, rb_intern("Digest"));
     DigestMD5 = rb_const_get(Digest, rb_intern("MD5"));
 
+    rb_define_singleton_method(ObjectId, "legal?", objectid_legal, 1);
+    rb_define_singleton_method(ObjectId, "from_string", objectid_from_string, 1);
     rb_define_method(ObjectId, "generate", objectid_generate, -1);
 
     if (gethostname(hostname, MAX_HOSTNAME_LENGTH) != 0) {