RetroShare/libretroshare/src/rsiface/rsexpr.h

#ifndef RS_EXPRESSIONS_H
#define RS_EXPRESSIONS_H

/*
 * rs-core/src/rsiface: rsexpr.h
 *
 * RetroShare C++ Interface.
 *
 * Copyright 2007-2008 by Kashif Kaleem.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License Version 2 as published by the Free Software Foundation.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA.
 *
 * Please report all bugs and problems to "retroshare@lunamutt.com".
 *
 */


#include <string>
#include <list>

/******************************************************************************************
Enumerations defining the Operators usable in the Boolean search expressions
******************************************************************************************/


enum LogicalOperator{
	AndOp=0,	/* exp AND exp */
	OrOp,		/* exp OR exp */
	XorOp		/* exp XOR exp */
};


/*Operators for String Queries*/
enum StringOperator{
	ContainsAnyStrings = 0,	/* e.g. name contains any of 'conference' 'meeting' 'presentation' */
	ContainsAllStrings,		/* same as above except that it contains ALL of the strings */
	EqualsString			/* exactly equal*/
};

/*Relational operators ( >, <, >=, <=, == and InRange )*/
enum RelOperator{
	Equals = 0,
	GreaterEquals,
	Greater,
	SmallerEquals,
	Smaller,
	InRange		/* lower limit <= value <= upper limit*/
};

/******************************************************************************************
Boolean Search Expression
classes:

	Expression: 		The base class of all expression typest
	CompoundExpression: The expression which uses a logical operator to combine
							the results of two expressions
	StringExpression: 	An expression which uses some sort of string comparison.
	RelExpression: 		A Relational Expression where > < >= <= == make sense. 
							e.g. size date etc

******************************************************************************************/

class FileEntry;

class Expression{
public:
	virtual bool eval (FileEntry *file) = 0;
	virtual ~Expression() {};
};


class CompoundExpression : public Expression {
public:	
	CompoundExpression( enum LogicalOperator op, Expression * exp1, Expression *exp2)
						: Lexp(exp1), Rexp(exp2), Op(op){ }
							
	bool eval (FileEntry *file) {
		if (Lexp == NULL or Rexp == NULL) {
			return false;	
		}
		switch (Op){
			case AndOp:
				return Lexp->eval(file) && Rexp->eval(file);
			case OrOp:
				return Lexp->eval(file) || Rexp->eval(file);
			case XorOp:
				return Lexp->eval(file) ^ Rexp->eval(file);
			default:
				return false;
		}
	}
	virtual ~CompoundExpression(){
		delete Lexp;
		delete Rexp;
	}	
private:
	Expression *Lexp;
	Expression *Rexp;
	enum LogicalOperator Op;

};

class StringExpression: public Expression {
public:
	StringExpression(enum StringOperator op, std::list<std::string> &t, 
					 bool ic): Op(op),terms(t), IgnoreCase(ic){}
protected:
	bool evalStr(std::string &str);
private:
	enum StringOperator Op;
	std::list<std::string> terms;
	bool IgnoreCase;
};

template <class T>
class RelExpression: public Expression {
public:	
	RelExpression(enum RelOperator op, T lv, T hv): 
				  Op(op), LowerValue(lv), HigherValue(hv) {}
protected:
	bool evalRel(T val);
private:
	enum RelOperator Op;
	T LowerValue;
	T HigherValue;
};

template <class T>
bool RelExpression<T>::evalRel(T val) {
	switch (Op) {
		case Equals:
			return LowerValue == val;
		case GreaterEquals:
			return LowerValue >= val;
		case Greater:
			return LowerValue > val;
		case SmallerEquals:
			return LowerValue <= val;
		case Smaller:
			return LowerValue < val;
		case InRange:
			return (LowerValue <= val) && (val <= HigherValue);
		default:
			return false;
	}
}


/******************************************************************************************
Binary Predicate for Case Insensitive search 

******************************************************************************************/
/*Binary predicate for case insensitive character comparison.*/
/*TODOS:
 *Factor locales in the comparison
 */
struct CompareCharIC :
                public std::binary_function< char , char , bool> {

        bool operator () ( char ch1 , char ch2 ) const {
                return tolower( static_cast < unsigned char > (ch1) )
                        == tolower( static_cast < unsigned char > (ch2) );
        }

};

/******************************************************************************************
Some implementations of StringExpressions. 

******************************************************************************************/

class NameExpression: public StringExpression {
public:
	NameExpression(enum StringOperator op, std::list<std::string> &t, bool ic): 
					StringExpression(op,t,ic) {}
	bool eval(FileEntry *file);
};

class PathExpression: public StringExpression {
public:
	PathExpression(enum StringOperator op, std::list<std::string> &t, bool ic): 
					StringExpression(op,t,ic) {}
	bool eval(FileEntry *file);
};

class ExtExpression: public StringExpression {
public:
	ExtExpression(enum StringOperator op, std::list<std::string> &t, bool ic): 
					StringExpression(op,t,ic) {}
	bool eval(FileEntry *file);
};

class HashExpression: public StringExpression {
public:
	HashExpression(enum StringOperator op, std::list<std::string> &t): 
					StringExpression(op,t, true) {}
	bool eval(FileEntry *file);
};

/******************************************************************************************
Some implementations of Relational Expressions.

******************************************************************************************/

class DateExpression: public RelExpression<int> {
public:
	DateExpression(enum RelOperator op, int v): RelExpression<int>(op,v,v){}
	DateExpression(enum RelOperator op, int lv, int hv): 
					RelExpression<int>(op,lv,hv) {}
	bool eval(FileEntry *file);
};

class SizeExpression: public RelExpression<int> {
public:
	SizeExpression(enum RelOperator op, int v): RelExpression<int>(op,v,v){}
	SizeExpression(enum RelOperator op, int lv, int hv): 
					RelExpression<int>(op,lv,hv) {}
	bool eval(FileEntry *file);
};

class PopExpression: public RelExpression<int> {
public:
	PopExpression(enum RelOperator op, int v): RelExpression<int>(op,v,v){}
	PopExpression(enum RelOperator op, int lv, int hv): 
					RelExpression<int>(op,lv,hv) {}
	bool eval(FileEntry *file);
};

#endif /* RS_EXPRESSIONS_H */