koffice/kexi/kexidb/expression.h

/* This file is part of the KDE project
   Copyright (C) 2003-2007 Jaroslaw Staniek <js@iidea.pl>

   Design based on nexp.h : Parser module of Python-like language
   (C) 2001 Jaroslaw Staniek, MIMUW (www.mimuw.edu.pl)

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   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; see the file COPYING.LIB.  If not, write to
   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
*/

#ifndef KEXIDB_EXPRESSION_H
#define KEXIDB_EXPRESSION_H

#include "field.h"
#include "queryschema.h"

#include <kdebug.h>
#include "global.h"

namespace KexiDB {

//! classes
#define KexiDBExpr_Unknown 0
#define KexiDBExpr_Unary 1
#define KexiDBExpr_Arithm 2
#define KexiDBExpr_Logical 3
#define KexiDBExpr_Relational 4
#define KexiDBExpr_SpecialBinary 5
#define KexiDBExpr_Const 6
#define KexiDBExpr_Variable 7
#define KexiDBExpr_Function 8
#define KexiDBExpr_Aggregation 9
#define KexiDBExpr_TableList 10
#define KexiDBExpr_QueryParameter 11

//! Custom tokens are not used in parser but used as extension in expression classes.
//#define KEXIDB_CUSTOM_TOKEN 0x1000

//! \return class name of class \a c
KEXI_DB_EXPORT TQString exprClassName(int c);

class ParseInfo;
class NArgExpr;
class UnaryExpr;
class BinaryExpr;
class ConstExpr;
class VariableExpr;
class FunctionExpr;
class QueryParameterExpr;
class QuerySchemaParameterValueListIterator;
//class QuerySchemaParameterList;

//! A base class for all expressions
class KEXI_DB_EXPORT BaseExpr
{
public:
	typedef TQPtrList<BaseExpr> List;
	typedef TQPtrListIterator<BaseExpr> ListIterator;

	BaseExpr(int token);
	virtual ~BaseExpr();

	//! \return a deep copy of this object.
//! @todo a nonpointer will be returned here when we move to implicit data sharing
	virtual BaseExpr* copy() const = 0;

	int token() const { return m_token; }
	
	virtual Field::Type type();
	
	BaseExpr* parent() const { return m_par; }
	
	virtual void setParent(BaseExpr *p) { m_par = p; }
	
	virtual bool validate(ParseInfo& parseInfo);

	/*! \return string as a representation of this expression element by running recursive calls. 
	 \a param, if not 0, points to a list item containing value of a query parameter
	 (used in QueryParameterExpr). */
	virtual TQString toString(QuerySchemaParameterValueListIterator* params = 0) = 0;

	/*! Collects query parameters (messages and types) reculsively and saves them to params.
	 The leaf nodes are objects of QueryParameterExpr class. */
	virtual void getQueryParameters(QuerySchemaParameterList& params) = 0;
	
	inline void debug() { KexiDBDbg << debugString() << endl; }
	
	virtual TQString debugString();
	
	/*! \return single character if the token is < 256 
	 or token name, e.g. LESS_OR_EQUAL (for debugging). */
	inline TQString tokenToDebugString() { return tokenToDebugString(m_token); }

	static TQString tokenToDebugString(int token);

	/*! \return string for token, like "<=" or ">" */
	virtual TQString tokenToString();

	int exprClass() const { return m_cl; }

	/*! Convenience type casts. */
	NArgExpr* toNArg();
	UnaryExpr* toUnary();
	BinaryExpr* toBinary();
	ConstExpr* toConst();
	VariableExpr* toVariable();
	FunctionExpr* toFunction();
	QueryParameterExpr* toQueryParameter();

protected:
	int m_cl; //!< class
	BaseExpr *m_par; //!< parent expression
	int m_token;
};

//! A base class N-argument operation
class KEXI_DB_EXPORT NArgExpr : public BaseExpr
{
public:
	NArgExpr(int aClass, int token);
	NArgExpr(const NArgExpr& expr);
	virtual ~NArgExpr();
	//! \return a deep copy of this object.
	virtual NArgExpr* copy() const;
	void add(BaseExpr *expr);
	void prepend(BaseExpr *expr);
	BaseExpr *arg(int n);
	int args();
	virtual TQString debugString();
	virtual TQString toString(QuerySchemaParameterValueListIterator* params = 0);
	virtual void getQueryParameters(QuerySchemaParameterList& params);
	virtual bool validate(ParseInfo& parseInfo);
	BaseExpr::List list;
};

//! An unary argument operation: + - NOT (or !) ~ "IS NULL" "IS NOT NULL" 
class KEXI_DB_EXPORT UnaryExpr : public BaseExpr
{
public:
	UnaryExpr(int token, BaseExpr *arg);
	UnaryExpr(const UnaryExpr& expr);
	virtual ~UnaryExpr();
	//! \return a deep copy of this object.
	virtual UnaryExpr* copy() const;
	virtual Field::Type type();
	virtual TQString debugString();
	virtual TQString toString(QuerySchemaParameterValueListIterator* params = 0);
	virtual void getQueryParameters(QuerySchemaParameterList& params);
	BaseExpr *arg() const { return m_arg; }
	virtual bool validate(ParseInfo& parseInfo);

	BaseExpr *m_arg;
};

/*! A base class for binary operation
 - arithmetic operations: + - / * % << >> & | ||
 - relational operations: = (or ==) < > <= >= <> (or !=) LIKE IN 'SIMILAR TO' 'NOT SIMILAR TO'
 - logical operations: OR (or ||) AND (or &&) XOR
 - SpecialBinary "pseudo operators": 
    * e.g. "f1 f2" : token == 0
    * e.g. "f1 AS f2" : token == AS
*/
class KEXI_DB_EXPORT BinaryExpr : public BaseExpr
{
public:
	BinaryExpr(int aClass, BaseExpr *left_expr, int token, BaseExpr *right_expr);
	BinaryExpr(const BinaryExpr& expr);
	virtual ~BinaryExpr();
	//! \return a deep copy of this object.
	virtual BinaryExpr* copy() const;
	virtual Field::Type type();
	virtual TQString debugString();
	virtual TQString toString(QuerySchemaParameterValueListIterator* params = 0);
	virtual void getQueryParameters(QuerySchemaParameterList& params);
	BaseExpr *left() const { return m_larg; }
	BaseExpr *right() const { return m_rarg; }
	virtual bool validate(ParseInfo& parseInfo);
	virtual TQString tokenToString();

	BaseExpr *m_larg;
	BaseExpr *m_rarg;
};

/*! String, integer, float constants also includes NULL value.
 token can be: IDENTIFIER, SQL_NULL, CHARACTER_STRING_LITERAL,
 INTEGER_CONST, REAL_CONST */
class KEXI_DB_EXPORT ConstExpr : public BaseExpr
{
public:
	ConstExpr(int token, const TQVariant& val);
	ConstExpr(const ConstExpr& expr);
	virtual ~ConstExpr();
	//! \return a deep copy of this object.
	virtual ConstExpr* copy() const;
	virtual Field::Type type();
	virtual TQString debugString();
	virtual TQString toString(QuerySchemaParameterValueListIterator* params = 0);
	virtual void getQueryParameters(QuerySchemaParameterList& params);
	virtual bool validate(ParseInfo& parseInfo);
	TQVariant value;
};

//! Query parameter used to getting user input of constant values.
//! It contains a message that is displayed to the user.
class KEXI_DB_EXPORT QueryParameterExpr : public ConstExpr
{
public:
	QueryParameterExpr(const TQString& message);
	QueryParameterExpr(const QueryParameterExpr& expr);
	virtual ~QueryParameterExpr();
	//! \return a deep copy of this object.
	virtual QueryParameterExpr* copy() const;
	virtual Field::Type type();
	/*! Sets expected type of the parameter. The default is String.
	 This method is called from parent's expression validate().
	 This depends on the type of the related expression.
	 For instance: query "SELECT * FROM cars WHERE name=[enter name]",
	 "[enter name]" has parameter of the same type as "name" field.
	 "=" binary expression's validate() will be called for the left side
	 of the expression and then the right side will have type set to String.
	*/
	void setType(Field::Type type);
	virtual TQString debugString();
	virtual TQString toString(QuerySchemaParameterValueListIterator* params = 0);
	virtual void getQueryParameters(QuerySchemaParameterList& params);
	virtual bool validate(ParseInfo& parseInfo);
protected:
	Field::Type m_type;
};

//! Variables like <i>fieldname</i> or <i>tablename</i>.<i>fieldname</i>
class KEXI_DB_EXPORT VariableExpr : public BaseExpr
{
public:
	VariableExpr(const TQString& _name);
	VariableExpr(const VariableExpr& expr);
	virtual ~VariableExpr();
	//! \return a deep copy of this object.
	virtual VariableExpr* copy() const;
	virtual Field::Type type();
	virtual TQString debugString();
	virtual TQString toString(QuerySchemaParameterValueListIterator* params = 0);
	virtual void getQueryParameters(QuerySchemaParameterList& params);

	/*! Validation. Sets field, tablePositionForField 
	 and tableForQueryAsterisk members. 
	 See addColumn() in parse.y to see how it's used on column adding. */
	virtual bool validate(ParseInfo& parseInfo);

	/*! Verbatim name as returned by scanner. */
	TQString name;

	/* NULL by default. After successful validate() it will point to a field,
	 if the variable is of a form "tablename.fieldname" or "fieldname", 
	 otherwise (eg. for asterisks) -still NULL.
	 Only meaningful for column expressions within a query. */
	Field *field;

	/* -1 by default. After successful validate() it will contain a position of a table
	 within query that needs to be bound to the field. 
	 This value can be either be -1 if no binding is needed.
	 This value is used in the Parser to call 
	  QuerySchema::addField(Field* field, int bindToTable);
	 Only meaningful for column expressions within a query. */
	int tablePositionForField;

	/*! NULL by default. After successful validate() it will point to a table
	 that is referenced by asterisk, i.e. "*.tablename". 
	 This is set to NULL if this variable is not an asterisk of that form. */
	TableSchema *tableForQueryAsterisk;
};

//! - aggregation functions like SUM, COUNT, MAX, ...
//! - builtin functions like CURRENT_TIME()
//! - user defined functions
class KEXI_DB_EXPORT FunctionExpr : public BaseExpr
{
public:
	FunctionExpr(const TQString& _name, NArgExpr* args_ = 0);
	FunctionExpr(const FunctionExpr& expr);
	virtual ~FunctionExpr();
	//! \return a deep copy of this object.
	virtual FunctionExpr* copy() const;
	virtual Field::Type type();
	virtual TQString debugString();
	virtual TQString toString(QuerySchemaParameterValueListIterator* params = 0);
	virtual void getQueryParameters(QuerySchemaParameterList& params);
	virtual bool validate(ParseInfo& parseInfo);

	static TQValueList<TQCString> builtInAggregates();
	static bool isBuiltInAggregate(const TQCString& fname);

	TQString name;
	NArgExpr* args;
};

} //namespace KexiDB

#endif