// SensibleFormat.h

// 

// Copyright (c) 2006 - 2010 Accenture. All rights reserved.

// This component and the accompanying materials are made available

// under the terms of the "Eclipse Public License v1.0"

// which accompanies this distribution, and is available

// at the URL "http://www.eclipse.org/legal/epl-v10.html".

// 

// Initial Contributors:

// Accenture - Initial contribution

//

// The purpose of this file is to define a generic format command that works reasonably even when there's no heap free

// Because it uses a stack buffer in this case, it is very difficult to make this a generic function without macroing

// Because I needed a 16-bit variant as well, and even templating would generate the same amount of code, I've done it

// as a #includable code snippet

// Note: If you do define SF_WIDE, Collapse() will be called on the result of the format before being passed to SF_ACTION

// If you want to pass in a VA_LIST, then #define SF_LIST aArgList

// If you want to pass in a bunch of arguments, #define SF_ARGLIST arg1,arg2,arg3

#if !defined(SF_FORMAT) || !defined(SF_BUF) || !defined(SF_ACTION)

#error "you must define all of SF_FORMAT, SF_BUF and SF_ACTION before including this file"

#endif

#if !((defined(SF_LIST) && !defined(SF_ARGLIST)) || (!defined(SF_LIST) && defined(SF_ARGLIST)))

#error "you must define exactly one of SF_LIST and SF_ARGLIST before including this file"

#endif

#ifndef COMMON_H

#error "you need to include common.h somewhere before including this file"

#endif

#ifdef SF_WIDE

#define TOverflowX TOverflow16

#define TBufX TBuf16<256>

#else

#define TOverflowX TOverflow8

#define TBufX TBuf8<256>

#endif

#ifdef SF_ARGLIST

#define SFAppend() AppendFormat(SF_FORMAT, &overflow, SF_ARGLIST)

#else

#define SFAppend() AppendFormatList(SF_FORMAT, SF_LIST, &overflow)

#endif

// Think of this as Format(RBuf8& SF_BUF, FunctionPointer SF_ACTION, const TDesCX& SF_FORMAT, TBool SF_STACKONLY, VA_LIST SF_LIST)

// where SF_ACTION(SF_BUF) is called passing in the fully formatted string

	{

	const TInt minBufSize = Max(SF_BUF.MaxSize(), 512);

	const TInt KMaxBufSize = 8192;

	TInt err = KErrNone;

#ifdef SF_STACKONLY

	if (SF_STACKONLY)

		{

		err = KErrNoMemory;

		}

	else

#endif

		{

		if (SF_BUF.MaxSize() == 0)

			{

			err = SF_BUF.Create(256);

			}

		else

			{

			SF_BUF.Zero();

			}

		}

	TOverflowX overflow;

	if (err == KErrNone)

		{

		// Do clever things to try and ensure that the format string won't be truncated, while at the same time not allocating an insanely big buffer

		for (TInt bufSize = minBufSize; bufSize <= KMaxBufSize; bufSize*=2)

			{

			#ifdef SF_WIDE

				TPtr16 widePtr((TUint16*)SF_BUF.Ptr(), SF_BUF.MaxSize()/2);

				widePtr.SFAppend();

			#else

				SF_BUF.SFAppend();

			#endif

			if (!overflow.iOverflow)

				{

				// Then the format went ok

				#ifdef SF_WIDE

					TPtr8 collapsed = widePtr.Collapse();

					SF_ACTION(collapsed);

				#else

					SF_ACTION(SF_BUF);

				#endif

				break;

				}

			else

				{

				// Overflowed

				if (bufSize == KMaxBufSize)

					{

					// We've grown up to our (self-imposed) max buf size, so just live with the truncation

					#ifdef SF_WIDE

						TPtr8 collapsed = widePtr.Collapse();

						SF_ACTION(collapsed);

					#else

						SF_ACTION(SF_BUF);

					#endif

					break;

					}

				// Try and grow

				SF_BUF.Close();

				err = SF_BUF.Create(bufSize*2);

				if (err) break;

				else continue;

				}

			}

		}

	if (err)

		{

		// Last resort, use 256 char buf on the stack

		TBufX stackBuf;

		stackBuf.SFAppend(); // Silently truncate if overflow happens now

		#ifdef SF_WIDE

			TPtr8 collapsed = stackBuf.Collapse();

			SF_ACTION(collapsed);

		#else

			SF_ACTION(stackBuf);

		#endif

		}

	}

#undef SF_WIDE

#undef SF_FORMAT

#undef SF_LIST

#undef SF_ARGLIST

#undef SF_BUF

#undef SF_ACTION

#undef TBufX

#undef TOverflowX

#undef SFAppend

#undef SF_STACKONLY