Revision: 6243
Author: [email protected]
Date: Mon Jan 10 03:44:54 2011
Log: Simplify Join and speedup joining arrays of numbers.
Review URL: http://codereview.chromium.org/6173004
http://code.google.com/p/v8/source/detail?r=6243
Modified:
/branches/bleeding_edge/src/array.js
=======================================
--- /branches/bleeding_edge/src/array.js Mon Jan 10 00:00:48 2011
+++ /branches/bleeding_edge/src/array.js Mon Jan 10 03:44:54 2011
@@ -117,19 +117,16 @@
// Fast case for one-element arrays.
if (length == 1) {
var e = array[0];
- if (!IS_UNDEFINED(e) || (0 in array)) {
- if (IS_STRING(e)) return e;
- return convert(e);
- }
- return '';
+ if (IS_STRING(e)) return e;
+ return convert(e);
}
// Construct an array for the elements.
var elements = new $Array(length);
- var elements_length = 0;
// We pull the empty separator check outside the loop for speed!
if (separator.length == 0) {
+ var elements_length = 0;
for (var i = 0; i < length; i++) {
var e = array[i];
if (!IS_UNDEFINED(e)) {
@@ -142,16 +139,25 @@
if (!IS_UNDEFINED(result)) return result;
return %StringBuilderConcat(elements, elements_length, '');
}
- // Non-empty separator.
- for (var i = 0; i < length; i++) {
- var e = array[i];
- if (!IS_UNDEFINED(e)) {
+ // Non-empty separator case.
+ // If the first element is a number then use the heuristic that the
+ // remaining elements are also likely to be numbers.
+ if (!IS_NUMBER(array[0])) {
+ for (var i = 0; i < length; i++) {
+ var e = array[i];
if (!IS_STRING(e)) e = convert(e);
elements[i] = e;
- } else {
- elements[i] = '';
- }
- }
+ }
+ } else {
+ for (var i = 0; i < length; i++) {
+ var e = array[i];
+ if (IS_NUMBER(e)) elements[i] = %_NumberToString(e);
+ else {
+ if (!IS_STRING(e)) e = convert(e);
+ elements[i] = e;
+ }
+ }
+ }
var result = %_FastAsciiArrayJoin(elements, separator);
if (!IS_UNDEFINED(result)) return result;
--
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