Avoid linear scan in GetEncoding and make the initialization lazy

diff --git a/mcs/class/corlib/System.Text/Encoding.cs b/mcs/class/corlib/System.Text/Encoding.cs
index 32e2312b45d8419a73118bbfe7ad01bce96521a0..1034f957fb3d9c750f126ba8ed3265fc7358dbdc 100644 (file)
--- a/mcs/class/corlib/System.Text/Encoding.cs
+++ b/mcs/class/corlib/System.Text/Encoding.cs
@@ -580,65 +580,72 @@ public abstract class Encoding : ICloneable
        }
 #endif // NET_2_1
 
-       // Table of builtin web encoding names and the corresponding code pages.
-       private static readonly object[] encodings =
-               {
-                       ASCIIEncoding.ASCII_CODE_PAGE,
-                       "ascii", "us_ascii", "us", "ansi_x3.4_1968",
-                       "ansi_x3.4_1986", "cp367", "csascii", "ibm367",
-                       "iso_ir_6", "iso646_us", "iso_646.irv:1991",
-
-                       UTF7Encoding.UTF7_CODE_PAGE,
-                       "utf_7", "csunicode11utf7", "unicode_1_1_utf_7",
-                       "unicode_2_0_utf_7", "x_unicode_1_1_utf_7",
-                       "x_unicode_2_0_utf_7",
-
-                       UTF8Encoding.UTF8_CODE_PAGE,
-                       "utf_8", "unicode_1_1_utf_8", "unicode_2_0_utf_8",
-                       "x_unicode_1_1_utf_8", "x_unicode_2_0_utf_8",
-
-                       UnicodeEncoding.UNICODE_CODE_PAGE,
-                       "utf_16", "UTF_16LE", "ucs_2", "unicode",
-                       "iso_10646_ucs2",
-
-                       UnicodeEncoding.BIG_UNICODE_CODE_PAGE,
-                       "unicodefffe", "utf_16be",
-
-                       UTF32Encoding.UTF32_CODE_PAGE,
-                       "utf_32", "UTF_32LE", "ucs_4",
-
-                       UTF32Encoding.BIG_UTF32_CODE_PAGE,
-                       "UTF_32BE",
-
-#if !MOONLIGHT
-                       Latin1Encoding.ISOLATIN_CODE_PAGE,
-                       "iso_8859_1", "latin1"
-#endif // !NET_2_1
-               };
-
        // Get an encoding object for a specific web encoding name.
-       public static Encoding GetEncoding (String name)
+       public static Encoding GetEncoding (string name)
        {
                // Validate the parameters.
                if (name == null) {
                        throw new ArgumentNullException ("name");
                }
-
+               
                string converted = name.ToLowerInvariant ().Replace ('-', '_');
                
-               // Search the table for a name match.
-               int code = 0;
-               for (int i = 0; i < encodings.Length; ++i) {
-                       object o = encodings [i];
-                       
-                       if (o is int){
-                               code = (int) o;
-                               continue;
-                       }
-                       
-                       if (converted == ((string)encodings [i]))
-                               return GetEncoding (code);
+               // Builtin web encoding names and the corresponding code pages.
+               switch (converted) {
+               case "ascii":
+               case "us_ascii":
+               case "us":
+               case "ansi_x3.4_1968":
+               case "ansi_x3.4_1986":
+               case "cp367":
+               case "csascii":
+               case "ibm367":
+               case "iso_ir_6":
+               case "iso646_us":
+               case "iso_646.irv:1991":
+                       return GetEncoding (ASCIIEncoding.ASCII_CODE_PAGE);
+
+               case "utf_7":
+               case "csunicode11utf7":
+               case "unicode_1_1_utf_7":
+               case "unicode_2_0_utf_7":
+               case "x_unicode_1_1_utf_7":
+               case "x_unicode_2_0_utf_7":
+                       return GetEncoding (UTF7Encoding.UTF7_CODE_PAGE);
+               
+               case "utf_8":
+               case "unicode_1_1_utf_8":
+               case "unicode_2_0_utf_8":
+               case "x_unicode_1_1_utf_8":
+               case "x_unicode_2_0_utf_8":
+                       return GetEncoding (UTF8Encoding.UTF8_CODE_PAGE);
+               
+               case "utf_16":
+               case "UTF_16LE":
+               case "ucs_2":
+               case "unicode":
+               case "iso_10646_ucs2":
+                       return GetEncoding (UnicodeEncoding.UNICODE_CODE_PAGE);
+
+               case "unicodefffe":
+               case "utf_16be":
+                       return GetEncoding (UnicodeEncoding.BIG_UNICODE_CODE_PAGE);
+               
+               case "utf_32":
+               case "UTF_32LE":
+               case "ucs_4":
+                       return GetEncoding (UTF32Encoding.UTF32_CODE_PAGE);
+
+               case "UTF_32BE":
+                       return GetEncoding (UTF32Encoding.BIG_UTF32_CODE_PAGE);
+
+#if !MOONLIGHT
+               case "iso_8859_1":
+               case "latin1":
+                       return GetEncoding (Latin1Encoding.ISOLATIN_CODE_PAGE);
+#endif
                }
+               
 #if !MOONLIGHT
                // Try to obtain a web encoding handler from the I18N handler.
                Encoding enc = (Encoding)(InvokeI18N ("GetEncoding", name));