Add JsDeserializeParserState method to deserialize parser state without executing it

Author: boingoing

bin/ChakraCore/ChakraCore.def

@@ -68,6 +68,7 @@ JsSetHostPromiseRejectionTracker
 JsGetProxyProperties
 JsSerializeParserState
 JsRunScriptWithParserState
+JsDeserializeParserState
 JsGetPromiseState
 JsGetPromiseResult
 

lib/Jsrt/ChakraCore.h

@@ -1582,6 +1582,46 @@ CHAKRA_API
         _In_ JsValueRef parserState,
         _Out_ JsValueRef * result);
 
+/// <summary>
+///     Deserializes the cache of initial parser state and (along with the same
+///     script source) returns a function representing that script.
+/// </summary>
+/// <remarks>
+///     <para>
+///         Requires an active script context.
+///     </para>
+///     <para>
+///         Script source can be either JavascriptString or JavascriptExternalArrayBuffer.
+///         In case it is an ExternalArrayBuffer, and the encoding of the buffer is Utf16,
+///         JsParseScriptAttributeArrayBufferIsUtf16Encoded is expected on parseAttributes.
+///     </para>
+///     <para>
+///         Use JavascriptExternalArrayBuffer with Utf8/ASCII script source
+///         for better performance and smaller memory footprint.
+///     </para>
+/// </remarks>
+/// <param name="script">The script to deserialize.</param>
+/// <param name="sourceContext">
+///     A cookie identifying the script that can be used by debuggable script contexts.
+/// </param>
+/// <param name="sourceUrl">The location the script came from</param>
+/// <param name="parseAttributes">Attribute mask for parsing the script</param>
+/// <param name="parserState">
+///     A buffer containing a cache of the parser state generated by <c>JsSerializeParserState</c>.
+/// </param>
+/// <param name="result">A function representing the script. This parameter can be null.</param>
+/// <returns>
+///     The code <c>JsNoError</c> if the operation succeeded, a failure code otherwise.
+/// </returns>
+CHAKRA_API
+    JsDeserializeParserState(
+        _In_ JsValueRef script,
+        _In_ JsSourceContext sourceContext,
+        _In_ JsValueRef sourceUrl,
+        _In_ JsParseScriptAttributes parseAttributes,
+        _In_ JsValueRef parserState,
+        _Out_ JsValueRef* result);
+
 typedef void (CHAKRA_CALLBACK *JsBeforeSweepCallback)(_In_opt_ void *callbackState);
 
 CHAKRA_API

lib/Jsrt/Jsrt.cpp

@@ -30,6 +30,7 @@ CHAKRA_API RunScriptWithParserStateCore(
     _In_ WCHAR *url,
     _In_ JsParseScriptAttributes parseAttributes,
     _In_ JsValueRef parserState,
+    _In_ bool parseOnly,
     _Out_ JsValueRef *result
 );
 
@@ -5370,7 +5371,6 @@ CHAKRA_API JsSerializeParserState(
     return errorCode;
 }
 
-
 static bool CHAKRA_CALLBACK DummyScriptLoadSourceCallbackForRunScriptWithParserState(
     JsSourceContext sourceContext,
     _Out_ JsValueRef *value,
@@ -5388,6 +5388,7 @@ CHAKRA_API RunScriptWithParserStateCore(
     _In_ WCHAR *url,
     _In_ JsParseScriptAttributes parseAttributes,
     _In_ JsValueRef parserState,
+    _In_ bool parseOnly,
     _Out_ JsValueRef *result
 )
 {
@@ -5480,7 +5481,7 @@ CHAKRA_API RunScriptWithParserStateCore(
     return RunSerializedScriptCore(
         dummy, DummyScriptUnloadCallback,
         sourceContext, // use the same user provided sourceContext as scriptLoadSourceContext
-        buffer, arrayBuffer, sourceContext, url, dwBgParseCookie, false, true, result, sourceIndex);
+        buffer, arrayBuffer, sourceContext, url, dwBgParseCookie, parseOnly, true, result, sourceIndex);
 }
 
 CHAKRA_API JsRunScriptWithParserState(
@@ -5495,14 +5496,33 @@ CHAKRA_API JsRunScriptWithParserState(
     if (sourceUrl && Js::VarIs<Js::JavascriptString>(sourceUrl))
     {
         url = const_cast<WCHAR*>(((Js::JavascriptString*)(sourceUrl))->GetSz());
-        return RunScriptWithParserStateCore(0, script, sourceContext, url, parseAttributes, parserState, result);
+        return RunScriptWithParserStateCore(0, script, sourceContext, url, parseAttributes, parserState, false, result);
     }
     else
     {
         return JsErrorInvalidArgument;
     }
 }
 
+CHAKRA_API JsDeserializeParserState(
+    _In_ JsValueRef script,
+    _In_ JsSourceContext sourceContext,
+    _In_ JsValueRef sourceUrl,
+    _In_ JsParseScriptAttributes parseAttributes,
+    _In_ JsValueRef parserState,
+    _Out_ JsValueRef * result)
+{
+    WCHAR *url = nullptr;
+    if (sourceUrl && Js::VarIs<Js::JavascriptString>(sourceUrl))
+    {
+        url = const_cast<WCHAR*>(((Js::JavascriptString*)(sourceUrl))->GetSz());
+        return RunScriptWithParserStateCore(0, script, sourceContext, url, parseAttributes, parserState, true, result);
+    }
+    else
+    {
+        return JsErrorInvalidArgument;
+    }
+}
 
 CHAKRA_API
 JsExecuteBackgroundParse_Experimental(
@@ -5524,6 +5544,7 @@ JsExecuteBackgroundParse_Experimental(
             url,
             parseAttributes,
             parserState,
+            false,
             result
         );
     }