[rygel] core: Pre-compile regex for substitute variables

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit c98f8c5f95e787467c7d04db6c2cdcb727912efd
Author: Zeeshan Ali (Khattak) <zeeshanak gnome org>
Date:   Fri Aug 20 22:40:01 2010 +0300

    core: Pre-compile regex for substitute variables
    
    Apparently these string comparisons were taking a hell lot of time and the
    reason was that string.replace() compiles regex each time it needs to
    replace a string.

 src/rygel/rygel-media-object.vala |   39 +++++++++++++++++++++++++++++++-----
 1 files changed, 33 insertions(+), 6 deletions(-)
---
diff --git a/src/rygel/rygel-media-object.vala b/src/rygel/rygel-media-object.vala
index 6b3a01e..c106e11 100644
--- a/src/rygel/rygel-media-object.vala
+++ b/src/rygel/rygel-media-object.vala
@@ -27,6 +27,10 @@ using Gee;
  * Represents a media object (container and item).
  */
 public abstract class Rygel.MediaObject : GLib.Object {
+    private static Regex real_name_regex;
+    private static Regex user_name_regex;
+    private static Regex host_name_regex;
+
     public string id;
     public string upnp_class;
     public uint64 modified;
@@ -60,12 +64,35 @@ public abstract class Rygel.MediaObject : GLib.Object {
         }
 
         set {
-            this._title = value.replace ("@REALNAME@",
-                                         Environment.get_real_name ());
-            _title = _title.replace ("@USERNAME@",
-                                     Environment.get_user_name ());
-            _title = _title.replace ("@HOSTNAME@",
-                                     Environment.get_host_name ());
+            try {
+                this._title = real_name_regex.replace_literal (
+                                        value,
+                                        -1,
+                                        0,
+                                        Environment.get_real_name ());
+                this._title = user_name_regex.replace_literal (
+                                        this._title,
+                                        -1,
+                                        0,
+                                        Environment.get_user_name ());
+                this._title = host_name_regex.replace_literal (
+                                                this._title,
+                                                -1,
+                                                0,
+                                                Environment.get_host_name ());
+            } catch (GLib.RegexError err) {
+                assert_not_reached ();
+            }
+        }
+    }
+
+    static construct {
+        try {
+            real_name_regex = new Regex (Regex.escape_string ("@REALNAME@"));
+            user_name_regex = new Regex (Regex.escape_string ("@USERNAME@"));
+            host_name_regex = new Regex (Regex.escape_string ("@HOSTNAME@"));
+        } catch (GLib.RegexError err) {
+            assert_not_reached ();
         }
     }