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<title>[184866] trunk/Source/JavaScriptCore</title>
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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/184866">184866</a></dd>
<dt>Author</dt> <dd>akling@apple.com</dd>
<dt>Date</dt> <dd>2015-05-26 11:56:42 -0700 (Tue, 26 May 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>String.prototype.charCodeAt() should use StringView.
<https://webkit.org/b/145353>
Reviewed by Darin Adler.
Use JSString::view() in charCodeAt() to avoid reifying the JSString if it's
a substring. This avoids StringImpl allocation in some cases and ref churn
in all cases.
* runtime/StringPrototype.cpp:
(JSC::stringProtoFuncCharCodeAt):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreruntimeStringPrototypecpp">trunk/Source/JavaScriptCore/runtime/StringPrototype.cpp</a></li>
</ul>
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<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (184865 => 184866)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2015-05-26 18:54:01 UTC (rev 184865)
+++ trunk/Source/JavaScriptCore/ChangeLog 2015-05-26 18:56:42 UTC (rev 184866)
</span><span class="lines">@@ -1,5 +1,19 @@
</span><span class="cx"> 2015-05-26 Andreas Kling <akling@apple.com>
</span><span class="cx">
</span><ins>+ String.prototype.charCodeAt() should use StringView.
+ <https://webkit.org/b/145353>
+
+ Reviewed by Darin Adler.
+
+ Use JSString::view() in charCodeAt() to avoid reifying the JSString if it's
+ a substring. This avoids StringImpl allocation in some cases and ref churn
+ in all cases.
+
+ * runtime/StringPrototype.cpp:
+ (JSC::stringProtoFuncCharCodeAt):
+
+2015-05-26 Andreas Kling <akling@apple.com>
+
</ins><span class="cx"> String.prototype.charAt() should use StringView.
</span><span class="cx"> <https://webkit.org/b/145352>
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreruntimeStringPrototypecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/runtime/StringPrototype.cpp (184865 => 184866)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/runtime/StringPrototype.cpp 2015-05-26 18:54:01 UTC (rev 184865)
+++ trunk/Source/JavaScriptCore/runtime/StringPrototype.cpp 2015-05-26 18:56:42 UTC (rev 184866)
</span><span class="lines">@@ -804,21 +804,17 @@
</span><span class="cx"> JSValue thisValue = exec->thisValue();
</span><span class="cx"> if (!checkObjectCoercible(thisValue))
</span><span class="cx"> return throwVMTypeError(exec);
</span><del>- String s = thisValue.toString(exec)->value(exec);
- unsigned len = s.length();
</del><ins>+ StringView string = thisValue.toString(exec)->view(exec);
</ins><span class="cx"> JSValue a0 = exec->argument(0);
</span><span class="cx"> if (a0.isUInt32()) {
</span><span class="cx"> uint32_t i = a0.asUInt32();
</span><del>- if (i < len) {
- if (s.is8Bit())
- return JSValue::encode(jsNumber(s.characters8()[i]));
- return JSValue::encode(jsNumber(s.characters16()[i]));
- }
</del><ins>+ if (i < string.length())
+ return JSValue::encode(jsNumber(string[i]));
</ins><span class="cx"> return JSValue::encode(jsNaN());
</span><span class="cx"> }
</span><span class="cx"> double dpos = a0.toInteger(exec);
</span><del>- if (dpos >= 0 && dpos < len)
- return JSValue::encode(jsNumber(s[static_cast<int>(dpos)]));
</del><ins>+ if (dpos >= 0 && dpos < string.length())
+ return JSValue::encode(jsNumber(string[static_cast<int>(dpos)]));
</ins><span class="cx"> return JSValue::encode(jsNaN());
</span><span class="cx"> }
</span><span class="cx">
</span></span></pre>
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