utf8fns.cpp

/* $RCSfile: $
 * $Revision: $ $Date: $
 * Auth: David Loffredo (loffredo@steptools.com)
 * 
 * Copyright (c) 1991-2015 by STEP Tools Inc. 
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "utf8fns.h"
#include <string.h>

using namespace System;
using namespace System::Text;
using namespace System::Runtime::InteropServices;

// Convert a managed UTF16 .NET string into a managed null-terminated
// UTF8 byte array.  When used with unmanaged code, you can then just
// pin the pointer to the byte array and use it as an unmanaged char*
//
array<unsigned char> ^ MakeNullTermUTF8 (String ^dotnet_str) 
{
    if (!dotnet_str) return nullptr;
    
    // Since we need to add a trailing null character, allocate the
    // character array ourself and then populate it with a variation
    // of the GetBytes call.

    // GetMaxByteCount is faster
    size_t bytesz = Encoding::UTF8->GetByteCount(dotnet_str);
    array<unsigned char> ^bytes = gcnew array<unsigned char>((int)bytesz + 1);
	
    // Copy to array, returns the number of bytes copies, use to null
    // terminate the array.
    size_t strlen = Encoding::UTF8->GetBytes(
	dotnet_str, 0, dotnet_str->Length, bytes, 0
	);
    bytes[(int)strlen] = 0;
    return bytes;
}


// Copy and convert an unmanaged null-terminated UTF8 string into a
// new managed UTF16 .NET String.
//
String ^ MakeStringFromUTF8 (const char * utf8_str)
{
    // Never return a null string from this interface
    // if (!utf8_str) return nullptr;
    if (!utf8_str) return String::Empty;

    size_t bytelen = strlen(utf8_str);
    if (!bytelen) return String::Empty;

    array<unsigned char> ^bytes = gcnew array<unsigned char>((int)bytelen);
    { 	
	pin_ptr<unsigned char> pinnedBytes = &bytes[0];
	memcpy(pinnedBytes, utf8_str, bytelen);
    }
    return Encoding::UTF8->GetString(bytes);
}