/*

* Copyright (c) 2004-2009 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of the License "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: 

* Definition of the CExpressionEvaluator

*

*/

/**

 @file

 @internalTechnology

 @released

*/

#ifndef __EXPRESSIONEVALUATOR_H__

#define __EXPRESSIONEVALUATOR_H__

#include <e32base.h>

#include "sisinstallerrors.h"

namespace Swi

{

class CApplication;

namespace Sis

	{

	class CExpression;

	}

/// Maximum recursion depth

const static TInt KMaxExpressionDepth=100;

/**

 * Class which provides an environment in which to evaluate 

 * CExpression expressions from a SISX file.

 *

 * @released

 * @internalTechnology

 */

class MExpressionEnvironment

	{

public:

	/**

	 * Check whether a file exists, corresponds to EXISTS() function in package format.

	 *

	 * @param aFileName	The filename to check for.

	 * @return 			ETrue if the file exists, EFalse otherwise.

	 */

	virtual TBool FileExistsL(const TDesC& aFileName)=0;

	/**

	 * Check whether a languageID exists within the list device supported languages.

	 *

	 * @param aLangId	The Language Id to check for.

	 * @return 			ETrue if the language exists, EFalse otherwise.

	 */

	virtual TBool DeviceLanguageL(const TDesC& aLangId)=0;

	/**

	 * Queries an application property, which is a key,value pair associated with

	 * an installed package. This corresponds to APPPROP() function in package format.

	 *

	 * @param aPackageUid	The UID of the package to look for the property in.

	 * @param aKey			The key to search for.

	 * @return				The value corresponding to the property found, or 0 if no

	 *						property was found with the given key.

	 */

	virtual TInt ApplicationPropertyL(TInt aPackageUid, TInt aKey)=0;

	/**

	 * Queries the registry to check if a package exists or not.

	 *

	 * @param aKey			The UID of the package to check

	 * @return				True if the package exists, false otherwise

	 */

	virtual TInt PackageL(TInt aKey)=0;

	/**

	 * Checks to see if an option was selected by the user.

	 *

	 * @param aOptionNumber	The number of the option in the SISX file to check.

	 * @return				ETrue if the option was selected, EFalse otherwise.

	 */	

	virtual TBool OptionL(TInt aOptionNumber)=0;

	/**

	 * Gets the value of a variable, indexed by a number.

	 *

	 * @param aVariableNumber	The number of the variable to look up.

	 * @return					The value of the variable.

	 */

	virtual TInt VariableL(TInt aVariableNumber)=0;

	/**

	 * Queries the registry to determine whether the version of a specific

	 * installed package satisfies the given relational condition 

	 * 

	 * @param aArgsString	The argument string should contain the following

	 * 						comma seperated parameters:

	 * 

	 * 						packageUid 			- 	UID of the package to check

	 *						relational Operator -	Comparision operator

	 * 						vMajor				-	Major Version component

	 * 						vMinor				-	Minor Version component

	 * 						vBuild				-	Build Version component					

	 * 

	 * @return				ETrue if the queried package version satisfies the

	 * 						condition, otherwise EFalse.

	 */

	virtual TBool PackageVersionL(const TDesC& aArgsString)=0;

	};

/**

 * Class which provides an environment in which to evaluate 

 * CExpression expressions from a SISX file.

 *

 * @released

 * @internalTechnology

 */

class CSwisExpressionEnvironment : public CBase, public MExpressionEnvironment

	{

public:

	static CSwisExpressionEnvironment* NewL(const CApplication& aAplication);

	static CSwisExpressionEnvironment* NewLC(const CApplication& aAplication);

protected:

	CSwisExpressionEnvironment(const CApplication& aApplication);

	// From MExpressionEnvironment

public:

	/**

	 * Check whether a file exists, corresponds to EXISTS() function in package format.

	 *

	 * @param aFileName	The filename to check for.

	 * @return 			ETrue if the file exists, EFalse otherwise.

	 */

	virtual TBool FileExistsL(const TDesC& aFileName);

	/**

	 * Queries an application property, which is a key,value pair associated with

	 * an installed package. This corresponds to APPPROP() function in package format.

	 *

	 * @param aPackageUid	The UID of the package to look for the property in.

	 * @param aKey			The key to search for.

	 * @return				The value corresponding to the property found, or 0 if no

	 *						property was found with the given key.

	 */

	virtual TInt ApplicationPropertyL(TInt aPackageUid, TInt aKey);

	/**

	 * Queries the registry to check if a package exists or not.

	 * This corresponds to package() function in package format.

	 *

	 * @param aKey			The key to search for.

	 * @return				True if the package exists, false otherwise

	 */

	virtual TInt PackageL(TInt aKey);

	/**

	 * Checks to see if an option was selected by the user.

	 *

	 * @param aOptionNumber	The number of the option in the SISX file to check.

	 * @return				ETrue if the option was selected, EFalse otherwise.

	 */	

	virtual TBool OptionL(TInt aOptionNumber);

	/**

	 * Gets the value of a variable, indexed by a number.

	 *

	 * @param aVariableNumber	The number of the variable to look up.

	 * @return					The value of the variable.

	 */

	virtual TInt VariableL(TInt aVariableNumber);

	/**

	 * Check whether a languageID exists within the list device supported languages.

	 *

	 * @param aLangId	The Language Id to check for.

	 * @return 			ETrue if the language exists, EFalse otherwise.

	 */

	virtual TBool DeviceLanguageL(const TDesC& aLanguageIdString);

	/**

	 * Queries the registry to determine whether the version of a specific

	 * installed package satisfies the given relational condition 

	 * 

	 * @param aArgsString	The argument string should contain the following

	 * 						comma seperated parameters:

	 * 

	 * 						packageUid 			- 	UID of the package to check

	 *						relational Operator -	Comparision operator

	 * 						vMajor				-	Major Version component

	 * 						vMinor				-	Minor Version component

	 * 						vBuild				-	Build Version component					

	 * 

	 * @return				ETrue if the queried package version satisfies the

	 * 						condition, otherwise EFalse.

	 */

	virtual TBool PackageVersionL(const TDesC& aArgsString);

private:

	TInt ParseLanguageId(const TDesC& aComponentString);	

private:

	/**

	 * Parses the argument string by searching for the next instance of the

	 * separator, sets the next token and updates the parse string with 

	 * the remaining arguments yet to be extracted.

	 * 

	 * @param aParseString	The current state of the parse string which is used

	 * 						to extract the next token. Once the token has been 

	 * 						extracted, the string is updated so that the 

	 * 						new token and separator are removed from the

	 * 						front of the string.

	 * 

	 * @param aTokenString	Reference to the TPtrC object in which the new token

	 * 						is to be stored.		

	 * 

	 * @return				KErrNone is returned if the separator was located and

	 * 						the token and parse strings have been set, Otherwise

	 * 						KErrNotFound is returned.

	 */

	TInt ExtractNextToken(TPtrC& aParseString, TPtrC& aTokenString);

	/**

	 * Checks the passed Package UID string, setting the Package UID (TUid)

	 * if successful.

	 * 

	 * @param aUidString	Hexadecimal UID string to be converted

	 * 						into a TUid.

	 * 

	 * @param aUid			Reference to the TUid object to be set if the

	 * 						parse is successful.			

	 * 

	 * @return				KErrNone is returned if the parse was successful

	 * 						and the TUid object has been set, Otherwise 

	 * 						KErrNotFound is returned.

	 */

	TInt ParsePackageUid(const TDesC& aUidString, TUid& aUid);

	/**

	 * Checks the passed version component string returning the version

	 * component value as a TInt.

	 * 

	 * Note: This function does NOT support Wildcards.

	 * 

	 * @param aComponentString	Version component string to be converted

	 * 							into a TInt.

	 * 

	 * @return					KErrNotFound if the parse fails, otherwise the decimal

	 * 							representation as a TInt.

	 */

	TInt ParseVersionComponent(const TDesC& aComponentString);

private:

	const CApplication& iApplication;

	};

/**

 * Class which provides an environment in which to evaluate CExpression

 * expressions from a SISX file, before any options have been chosen.

 *

 * @released

 * @internalTechnology

 */

class CSwisCreateExpressionEnvironment : public CSwisExpressionEnvironment

	{

public:

	static CSwisCreateExpressionEnvironment* NewL(const CApplication& aAplication);

	static CSwisCreateExpressionEnvironment* NewLC(const CApplication& aAplication);

private:

	CSwisCreateExpressionEnvironment(const CApplication& aApplication);

public:

	/**

	 * Returns ETrue, regardless of the selected option.

	 *

	 * @param aOptionNumber	The number of the option in the SISX file to check.

	 * @return				ETrue.

	 */	

	virtual TBool OptionL(TInt aOptionNumber);	

private:

	const CApplication& iApplication;

	};

/**

 * Class to provide the result of an expression evaluation.

 */

class TExpressionResult

	{

public:

	enum TType { EString, EInt };

	TExpressionResult(const TDesC& aString);

	TExpressionResult(TInt aInt);

	TInt IntegerValueL() const;

	TBool BoolValueL() const;

	const TDesC& StringValueL() const;

	TType Type() const;	

//	friend TExpressionResult operator!(const TExpressionResult& aExpression);

private:

	TType iType;

	union

		{

		const TDesC* iString; // Needs to be Pointer due to initialisation

		TInt iInt;

		};

	};

TExpressionResult operator!=(const TExpressionResult& aLhs, const TExpressionResult& aRhs);

TExpressionResult operator==(const TExpressionResult& aLhs, const TExpressionResult& aRhs);

TExpressionResult operator<(const TExpressionResult& aLhs, const TExpressionResult& aRhs);

TExpressionResult operator>(const TExpressionResult& aLhs, const TExpressionResult& aRhs);

TExpressionResult operator<=(const TExpressionResult& aLhs, const TExpressionResult& aRhs);

TExpressionResult operator>=(const TExpressionResult& aLhs, const TExpressionResult& aRhs);

TExpressionResult operator!(const TExpressionResult& aExpression);

/**

 * Class which evaluates CExpression expressions from a SISX file.

 *

 * @released

 * @internalTechnology

 */

class CExpressionEvaluator : public CBase

	{

public:

	/**

	 * This creates a new CExpressionEvaluator object.

	 * @param aEnvironment	The environment to carry out the expression in.

	 *						This provides, lookup of options, etc.

	 */

	static CExpressionEvaluator* NewL(MExpressionEnvironment& aEnvironment);

	/**

	 * This creates a new CExpressionEvaluator object and leaves it in the cleanup stack.

	 * @param aEnvironment	The environment to carry out the expression in.

	 *						This provides, lookup of options, etc.

	 */

	static CExpressionEvaluator* NewLC(MExpressionEnvironment& aEnvironment);

	/**

	 * Evaluate the expression.

	 * 

	 * @param aExpression	The expression to be evaluated.

	 * @return					The result of the expression evaluation.

	 */

	TExpressionResult EvaluateL(const Sis::CExpression& aExpression);

	/**

	 * Evaluate the expression.

	 * 

	 * @param aExpression	The expression to be evaluated.

	 * @return					The result of the expression evaluation.

	 */

	TExpressionResult EvaluateL(const Sis::CExpression* aExpression);

private:

	/// Constructor

	CExpressionEvaluator(MExpressionEnvironment& aEnvironment);

	/// This function leaves with KErrSwiInvalidExpression if the pointers passed are NULL

	void RequireL(const void *aPointer) const;

private:

	/// The environment to carry out expression evaluation in

	MExpressionEnvironment& iEnvironment;

	/** 

	 * The depth of the expression currently being evaluated, used to prevent attempts to evaluate

	 * too complex expressions, which would cause stack overflows.

	 */

	TInt iExpressionDepth;

	/**

	 * Used to hold the result temporarily, between evaluating the recursive expression

	 * and returning the result, while the depth counter is decremented.

	 */

	TExpressionResult iTemporaryResult;

	};

#include "expressionevaluator.inl"

} // end namespace Swi

#endif