/*

 * Copyright (c) 2003-2009 Nokia Corporation and/or its subsidiary(-ies).

 * All rights reserved.

 * This component and the accompanying materials are made available

 * under the terms of "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:

 * Nokia Corporation - initial contribution.

 *

 * Contributors:

 *

 * Description:

 * Definitions for bidirectional text reordering.

 * 

 *

 */

 #ifndef BIDI_H_

 #define BIDI_H_

 #include <e32std.h>

 class RWriteStream;

 class RReadStream;

 class TBidirectionalState

 /** 

 The bidirectional state class. 

 This class contains functions that implement the Unicode Bidirectional Algorithm, 

 which changes text from logical order to display order for the correct display 

 of right-to-left scripts, like Arabic and Hebrew. A TBidirectionalState object 

 carries the embedding level and stack from one line to the next. On construction 

 it is in its 'start of paragraph' state. 

 @publishedAll

 @released

 */

 	{

 	friend class CTBiDi;

 public:

 	class TRunInfo

 	/** 

 	Information about a run of characters with the same bidirectional 

 	category. 

 	An array of these representing a line is passed into, and reordered by, 

 	ReorderLine(). 

 	@publishedAll

 	@released

 	*/

 		{

 		public:

 		/** Category of a run of text: passed to ReorderLine(); these are 

 		passed in as TChar::TBdCategory values but are modified for internal 

 		use. */

 		TUint iCategory;		

 		/** Embedding level of this run: used internally by ReorderLine(). */

 		TUint8 iEmbeddingLevel;	

 		/** Resolved direction of this run: 0 for left to right, 1 for right 

 		to left. */

 		TUint8 iDirection;		

 		/** Index of this run after reordering. */

 		TInt iIndex;			

 		/** Start of text; returned by ReorderText(). */

 		TInt iStart;			

 		/** Length of text; returned by ReorderText(). */

 		TInt iLength;			

 		};

 	IMPORT_C TBidirectionalState();

 	IMPORT_C void ReorderLine(TRunInfo* aRunInfo,TInt aRuns,TBool aParStart,TBool aParEnd,TBool aParRightToLeft,

 					 TChar::TBdCategory aNextCategory,TChar::TBdCategory aNextStrongCategory,

 					 TBool& aVisualEndIsAmbiguous);

 	IMPORT_C void ReorderLine(TRunInfo* aRunInfo,TInt aRuns,TBool aParStart,TBool aParEnd,TBool aParRightToLeft,

 					 TChar::TBdCategory aNextCategory,TChar::TBdCategory aNextStrongCategory);

 	IMPORT_C static TInt ReorderText(const TText* aText,TInt aLength,TBool aParRightToLeft,TText*& aNewText);

 	IMPORT_C static void ReverseGroups(TText* aStart,TInt aLength);

 	IMPORT_C void Reset();

 	IMPORT_C TBool IsDefault() const;

 	IMPORT_C TBool operator==(const TBidirectionalState& aState) const;

 	IMPORT_C void ExternalizeL(RWriteStream& aDest);

 	IMPORT_C void InternalizeL(RReadStream& aSource);

 	TBool ParRightToLeft() const { return iStack[0].iEmbeddingLevel & 1; }

 private:

 	// Bidirectional categories coded as bit flags

 	enum TCategory

 		{

 		ELeftToRight = 1 << TChar::ELeftToRight, 

 		ELeftToRightEmbedding = 1 << TChar::ELeftToRightEmbedding,

 		ELeftToRightOverride = 1 << TChar::ELeftToRightOverride,

 		ERightToLeft = 1 << TChar::ERightToLeft,

 		ERightToLeftArabic = 1 << TChar::ERightToLeftArabic,

 		ERightToLeftEmbedding = 1 << TChar::ERightToLeftEmbedding, 

 		ERightToLeftOverride = 1 << TChar::ERightToLeftOverride,

 		EPopDirectionalFormat = 1 << TChar::EPopDirectionalFormat, 

 		EEuropeanNumber = 1 << TChar::EEuropeanNumber, 

 		EEuropeanNumberSeparator = 1 << TChar::EEuropeanNumberSeparator, 

 		EEuropeanNumberTerminator = 1 << TChar::EEuropeanNumberTerminator, 

 		EArabicNumber = 1 << TChar::EArabicNumber,

 		ECommonNumberSeparator = 1 << TChar::ECommonNumberSeparator, 

 		ENonSpacingMark = 1 << TChar::ENonSpacingMark, 

 		EBoundaryNeutral = 1 << TChar::EBoundaryNeutral, 

 		EParagraphSeparator = 1 << TChar::EParagraphSeparator, 

 		ESegmentSeparator = 1 << TChar::ESegmentSeparator, 

 		EWhitespace = 1 << TChar::EWhitespace, 

 		EOtherNeutral = 1 << TChar::EOtherNeutral,

 		// useful groups

 		EBdControlsGroup = ELeftToRightEmbedding | ERightToLeftEmbedding |

 						   ELeftToRightOverride | ERightToLeftOverride | EPopDirectionalFormat,

 		ELeftToRightGroup = ELeftToRight | EEuropeanNumber | ELeftToRightOverride | ELeftToRightEmbedding,

 		ERightToLeftGroup = ERightToLeft | EArabicNumber | ERightToLeftArabic | ERightToLeftOverride |

 							ERightToLeftEmbedding,

 		EStrongGroup = ELeftToRightEmbedding | ERightToLeftEmbedding

 			| ELeftToRightOverride | ERightToLeftOverride

 			| ELeftToRight | ERightToLeft | ERightToLeftArabic,

 		ENoCategory = 0

 		};

 	enum

 		{

 		EMaxExplicitLevel = 61,

 		EMaxLevel = 63,

 		EMaxStackLevels = 62

 		};

 	enum TOverrideState

 		{

 		ENoOverrideState = 0,

 		ELeftToRightOverrideState = ELeftToRightOverride,

 		ERightToLeftOverrideState = ERightToLeftOverride

 		};

 	class TStackItem

 		{

 	public:

 		TUint8 iEmbeddingLevel;			// embedding level

 		TOverrideState iOverrideState;	// directional override state

 		TCategory iStartCategory;		// category that started this level; EOtherNeutral if none

 		};

 private:

 	/**	The information needed during line reordering.

 	WARNING: Class for internal use ONLY.  Compatibility is not guaranteed in future releases.	

 	 */

 	class TReorderContext

 		{

 	public:

 		void SetNextCategory(TChar::TBdCategory aCat);

 		void SetNextStrongCategory(TChar::TBdCategory aCat);

 	public:

 		/** Category at start of next line, or ON if at the end of the

 		paragraph. */

 		TCategory iNextCategory;

 		/** Which of L, R or AL appears first in the remainder of the

 		paragraph, or ON if none. */

 		TCategory iNextStrongCategory;

 		/** The run array for this line. */

 		TRunInfo* iRunInfo;

 		/** The length of iRunInfo. */

 		TInt iRuns;

 		/** Bitmap of categories currently present in iRunInfo. */

 		TUint32 iCategories;

 		/** Found by the algorithm to set iPreviousStrongCategory. */

 		TCategory iLastStrongCategory;

 		};

 public:

 	static TInt GenerateBdRunArray(const TText* aText, TInt aLength,

 		TBidirectionalState::TRunInfo* aRun, TInt aMaxRuns);

 private:

 	const TStackItem& State() const { return iStack[iStackLevel]; }

 	TCategory Push(TCategory aStartCategory);

 	TCategory Pop();

 public:

 	TBidirectionalState(TChar::TBdCategory aPrevCat,

 		TChar::TBdCategory aPrevStrongCat, TBool aParRightToLeft);

 	void HandleBdControls(TReorderContext& aContext); 

 	void ResolveWeakTypesW1W2W3(TReorderContext& aContext);

 	void ResolveWeakTypesW4W5W6(TReorderContext& aContext); 

 	void ResolveWeakTypesW7(TReorderContext& aContext); 

 	void ResolveNeutralTypes(TReorderContext& aContext); 

 	void ResolveImplicitLevels(TReorderContext& aContext); 

 	void PrepareForNextLine(const TReorderContext& aContext);

 	void ReorderRuns(TReorderContext& aContext);

 	static TInt CatToNumber(TInt aCat);

 	static TCategory CharToBdCat(TChar::TBdCategory aCat);

 	static TCategory UintToBdCat(TUint aCat);

 	static void DeneutralizeRuns(TRunInfo* aStart, TRunInfo* aEnd,

 		TCategory aStartCategory, TCategory aEndCategory);

 private:

 	TCategory iPreviousCategory;			// category at end of last line, or EStartOfParagraph if at start of par

 	TCategory iPreviousStrongCategory;		// L or R; derived from embedding level if at start of par

 	TInt16 iStackLevel;						// current stack level

 	TInt8 iPushesBeyond60;	// number of times Push called with iStackLevel == 60 and Left-To-Right category

 	TInt8 iPushesBeyond61;	// number of times Push called with iStackLevel == 61

 	TStackItem iStack[EMaxStackLevels];		// the stack of embedding levels

 	};

 #endif // BIDI_H_