|
private CreateStringArray ( |
||
| engine | ||
| items | char | |
| length | ||
| return | HandleProxy* | |
/// <summary>
/// Calls the native V8 proxy library to create the value instance for use within the V8 JavaScript environment.
/// <para>This overload provides a *quick way* to construct an array of strings.
/// One big memory block is created to marshal the given strings at one time, which is many times faster than having to create an array of individual native strings.</para>
/// </summary>
public InternalHandle CreateValue(IEnumerable <string> items)
{
if (items == null)
{
return(V8NetProxy.CreateArray(_NativeV8EngineProxy, null, 0));
}
var itemsEnum = items.GetEnumerator();
int strBufSize = 0; // (size needed for the string chars portion of the memory block)
int itemsCount = 0;
while (itemsEnum.MoveNext())
{
// get length of all strings together
strBufSize += itemsEnum.Current.Length + 1; // (+1 for null char)
itemsCount++;
}
itemsEnum.Reset();
int strPtrBufSize = Marshal.SizeOf(typeof(IntPtr)) * itemsCount; // start buffer size with size needed for all string pointers.
char **oneBigStringBlock = (char **)Utilities.AllocNativeMemory(strPtrBufSize + Marshal.SystemDefaultCharSize * strBufSize);
char **ptrWritePtr = oneBigStringBlock;
char * strWritePtr = (char *)(((byte *)oneBigStringBlock) + strPtrBufSize);
int itemLength;
while (itemsEnum.MoveNext())
{
itemLength = itemsEnum.Current.Length;
Marshal.Copy(itemsEnum.Current.ToCharArray(), 0, (IntPtr)strWritePtr, itemLength);
Marshal.WriteInt16((IntPtr)(strWritePtr + itemLength), 0);
Marshal.WriteIntPtr((IntPtr)ptrWritePtr++, (IntPtr)strWritePtr);
strWritePtr += itemLength + 1;
}
InternalHandle handle = V8NetProxy.CreateStringArray(_NativeV8EngineProxy, oneBigStringBlock, itemsCount);
Utilities.FreeNativeMemory((IntPtr)oneBigStringBlock);
return(handle);
}