Fixing bug 245619. Don't bother serializing the result of JS execution when the caller doesn't care about the value. r+sr=brendan@mozilla.org

content/base/src/nsScriptLoader.cpp

@@ -665,7 +665,6 @@ nsScriptLoader::EvaluateScript(nsScriptLoadRequest* aRequest,
   // have one.
   NS_ASSERTION(principal, "principal required for document");
 
-  nsAutoString ret;
   nsCAutoString url;
 
   if (aRequest->mURI) {
@@ -679,8 +678,8 @@ nsScriptLoader::EvaluateScript(nsScriptLoadRequest* aRequest,
 
   PRBool isUndefined;
   context->EvaluateString(aScript, nsnull, principal, url.get(),
-                          aRequest->mLineNo, aRequest->mJSVersion, 
-                          ret, &isUndefined);  
+                          aRequest->mLineNo, aRequest->mJSVersion, nsnull,
+                          &isUndefined);  
 
   context->SetProcessingScriptTag(PR_FALSE);
 

dom/public/nsIScriptContext.h

@@ -79,7 +79,7 @@ public:
    * @param aURL the URL or filename for error messages
    * @param aLineNo the starting line number of the script for error messages
    * @param aVersion the script language version to use when executing
-   * @param aRetValue the result of executing the script
+   * @param aRetValue the result of executing the script, or null for no result
    * @param aIsUndefined true if the result of executing the script is the
    *                     undefined value
    *
@@ -92,7 +92,7 @@ public:
                                   const char *aURL,
                                   PRUint32 aLineNo,
                                   const char* aVersion,
-                                  nsAString& aRetValue,
+                                  nsAString *aRetValue,
                                   PRBool* aIsUndefined) = 0;
 
   virtual nsresult EvaluateStringWithValue(const nsAString& aScript,

dom/src/base/nsGlobalWindow.cpp

@@ -4993,11 +4993,10 @@ GlobalWindowImpl::RunTimeout(nsTimeoutImpl *aTimeout)
         NS_REINTERPRET_CAST(const PRUnichar *,
                             ::JS_GetStringChars(timeout->mExpr));
 
-      nsAutoString retval;
       PRBool is_undefined;
       mContext->EvaluateString(nsDependentString(script), mJSObject,
                                timeout->mPrincipal, timeout->mFileName,
-                               timeout->mLineNo, timeout->mVersion, retval,
+                               timeout->mLineNo, timeout->mVersion, nsnull,
                                &is_undefined);
     } else {
       PRInt64 lateness64;

dom/src/base/nsJSEnvironment.cpp

@@ -746,8 +746,9 @@ nsJSContext::EvaluateStringWithValue(const nsAString& aScript,
                                               aLineNo,
                                               &val);
 
-      if (aVersion)
+      if (aVersion) {
         ::JS_SetVersion(mContext, oldVersion);
+      }
 
       if (!ok) {
         // Tell XPConnect about any pending exceptions. This is needed
@@ -838,12 +839,16 @@ nsJSContext::EvaluateString(const nsAString& aScript,
                             const char *aURL,
                             PRUint32 aLineNo,
                             const char* aVersion,
-                            nsAString& aRetValue,
+                            nsAString *aRetValue,
                             PRBool* aIsUndefined)
 {
   if (!mScriptsEnabled) {
     *aIsUndefined = PR_TRUE;
-    aRetValue.Truncate();
+
+    if (aRetValue) {
+      aRetValue->Truncate();
+    }
+
     return NS_OK;
   }
 
@@ -940,14 +945,16 @@ nsJSContext::EvaluateString(const nsAString& aScript,
 
   // If all went well, convert val to a string (XXXbe unless undefined?).
   if (ok) {
-    rv = JSValueToAString(mContext, val, &aRetValue, aIsUndefined);
+    rv = JSValueToAString(mContext, val, aRetValue, aIsUndefined);
   }
   else {
     if (aIsUndefined) {
       *aIsUndefined = PR_TRUE;
     }
 
-    aRetValue.Truncate();
+    if (aRetValue) {
+      aRetValue->Truncate();
+    }
   }
 
   ScriptEvaluated(PR_TRUE);

dom/src/base/nsJSEnvironment.h

@@ -64,7 +64,7 @@ public:
                                   const char *aURL,
                                   PRUint32 aLineNo,
                                   const char* aVersion,
-                                  nsAString& aRetValue,
+                                  nsAString *aRetValue,
                                   PRBool* aIsUndefined);
   virtual nsresult EvaluateStringWithValue(const nsAString& aScript,
                                      void *aScopeObject,

dom/src/jsurl/nsJSProtocolHandler.cpp

@@ -281,7 +281,7 @@ nsresult nsJSThunk::EvaluateScript(nsIChannel *aChannel)
                                        url.get(),      // url
                                        1,              // line no
                                        nsnull,
-                                       result,
+                                       &result,
                                        &bIsUndefined);
 
     if (NS_FAILED(rv)) {

extensions/xmlterm/base/mozXMLTermUtils.cpp

@@ -274,7 +274,7 @@ mozXMLTermUtils::ExecuteScript(nsIDOMDocument* aDOMDocument,
   const char* URL = "";
   result = scriptContext->EvaluateString(aScript, (void *) nsnull,
                                          docPrincipal, URL, 0, nsnull,
-                                         aOutput, &isUndefined);
+                                         &aOutput, &isUndefined);
 
   XMLT_LOG(mozXMLTermUtils::ExecuteScript,21,("result=0x%x,isUndefined=0x%x\n",
                                              result, isUndefined));