Improve array to string conversion.

src/uri.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 147 matching lines @@
         } else {
           throw new $URIError("URI malformed");
         }
       }
     }
   }
   if (0xD800 <= value && value <= 0xDFFF) {
     throw new $URIError("URI malformed");
   }
   if (value < 0x10000) {
-    result[index++] = value;
+    %_TwoByteSeqStringSetChar(result, index++, value);
     return index;
   } else {
-    result[index++] = (value >> 10) + 0xd7c0;
-    result[index++] = (value & 0x3ff) + 0xdc00;
+    %_TwoByteSeqStringSetChar(result, index++, (value >> 10) + 0xd7c0);
+    %_TwoByteSeqStringSetChar(result, index++, (value & 0x3ff) + 0xdc00);
     return index;
   }
 }
 
 
 // ECMA-262, section 15.1.3
 function Encode(uri, unescape) {
   var uriLength = uri.length;
-  // We are going to pass result to %StringFromCharCodeArray
-  // which does not expect any getters/setters installed
-  // on the incoming array.
-  var result = new InternalArray(uriLength);
+  var array = new InternalArray(uriLength);
   var index = 0;
   for (var k = 0; k < uriLength; k++) {
     var cc1 = uri.charCodeAt(k);
     if (unescape(cc1)) {
-      result[index++] = cc1;
+      array[index++] = cc1;
     } else {
       if (cc1 >= 0xDC00 && cc1 <= 0xDFFF) throw new $URIError("URI malformed");
       if (cc1 < 0xD800 || cc1 > 0xDBFF) {
-        index = URIEncodeSingle(cc1, result, index);
+        index = URIEncodeSingle(cc1, array, index);
       } else {
         k++;
         if (k == uriLength) throw new $URIError("URI malformed");
         var cc2 = uri.charCodeAt(k);
         if (cc2 < 0xDC00 || cc2 > 0xDFFF) throw new $URIError("URI malformed");
-        index = URIEncodePair(cc1, cc2, result, index);
+        index = URIEncodePair(cc1, cc2, array, index);
       }
     }
   }
-  return %StringFromCharCodeArray(result);
+
+  var result = %NewString(array.length, true);
+  for (var i = 0; i < array.length; i++) {
+    %_OneByteSeqStringSetChar(result, i, array[i]);
+  }
+  return result;
 }
 
 
 // ECMA-262, section 15.1.3
 function Decode(uri, reserved) {
   var uriLength = uri.length;
-  // We are going to pass result to %StringFromCharCodeArray
-  // which does not expect any getters/setters installed
-  // on the incoming array.
-  var result = new InternalArray(uriLength);
+  var one_byte = %NewString(uriLength, true);
   var index = 0;
-  for (var k = 0; k < uriLength; k++) {
-    var ch = uri.charAt(k);
-    if (ch == '%') {
+  var k = 0;
+
+  // Optimistically assume ascii string.
+  for ( ; k < uriLength; k++) {
+    var code = uri.charCodeAt(k);
+    if (code == 37) {  // '%'
+      if (k + 2 >= uriLength) throw new $URIError("URI malformed");
+      var cc = URIHexCharsToCharCode(uri.charCodeAt(k+1), uri.charCodeAt(k+2));
+      if (cc >> 7) break;  // Assumption wrong, two byte string.
+      if (reserved(cc)) {
+        %_OneByteSeqStringSetChar(one_byte, index++, 37);  // '%'.
+        %_OneByteSeqStringSetChar(one_byte, index++, uri.charCodeAt(k+1));
+        %_OneByteSeqStringSetChar(one_byte, index++, uri.charCodeAt(k+2));
+      } else {
+        %_OneByteSeqStringSetChar(one_byte, index++, cc);
+      }
+      k += 2;
+    } else {
+      if (code > 0x7f) break;  // Assumption wrong, two byte string.
+      %_OneByteSeqStringSetChar(one_byte, index++, code);
+    }
+  }
+
+  one_byte = TruncateString(one_byte, index);
+  if (k == uriLength) return one_byte;
+
+  // Write into two byte string.
+  var two_byte = %NewString(uriLength - k, false);
+  index = 0;
+
+  for ( ; k < uriLength; k++) {
+    var code = uri.charCodeAt(k);
+    if (code == 37) {  // '%'
       if (k + 2 >= uriLength) throw new $URIError("URI malformed");
       var cc = URIHexCharsToCharCode(uri.charCodeAt(++k), uri.charCodeAt(++k));
       if (cc >> 7) {
         var n = 0;
         while (((cc << ++n) & 0x80) != 0) { }
         if (n == 1 || n > 4) throw new $URIError("URI malformed");
         var octets = new $Array(n);
         octets[0] = cc;
         if (k + 3 * (n - 1) >= uriLength) throw new $URIError("URI malformed");
         for (var i = 1; i < n; i++) {
           if (uri.charAt(++k) != '%') throw new $URIError("URI malformed");
           octets[i] = URIHexCharsToCharCode(uri.charCodeAt(++k),
                                             uri.charCodeAt(++k));
         }
-        index = URIDecodeOctets(octets, result, index);
+        index = URIDecodeOctets(octets, two_byte, index);
+      } else  if (reserved(cc)) {
+        %_TwoByteSeqStringSetChar(two_byte, index++, 37);  // '%'.
+        %_TwoByteSeqStringSetChar(two_byte, index++, uri.charCodeAt(k - 1));
+        %_TwoByteSeqStringSetChar(two_byte, index++, uri.charCodeAt(k));
       } else {
-        if (reserved(cc)) {
-          result[index++] = 37; // Char code of '%'.
-          result[index++] = uri.charCodeAt(k - 1);
-          result[index++] = uri.charCodeAt(k);
-        } else {
-          result[index++] = cc;
-        }
+        %_TwoByteSeqStringSetChar(two_byte, index++, cc);
       }
     } else {
-      result[index++] = ch.charCodeAt(0);
+      %_TwoByteSeqStringSetChar(two_byte, index++, code);
     }
   }
-  result.length = index;
-  return %StringFromCharCodeArray(result);
+
+  two_byte = TruncateString(two_byte, index);
+  return one_byte + two_byte;
 }
 
 
 // ECMA-262 - 15.1.3.1.
 function URIDecode(uri) {
   var reservedPredicate = function(cc) {
     // #$
     if (35 <= cc && cc <= 36) return true;
     // &
     if (cc == 38) return true;
@@ skipping 157 matching lines @@
     "escape", URIEscape,
     "unescape", URIUnescape,
     "decodeURI", URIDecode,
     "decodeURIComponent", URIDecodeComponent,
     "encodeURI", URIEncode,
     "encodeURIComponent", URIEncodeComponent
   ));
 }
 
 SetUpUri();