ExpEvaluator Class Reference

An expression parser and evaluator. More...

#include <yateclass.h>

List of all members.

Public Types
enum	Parser { C, SQL }
enum	Opcode {   OpcNone, OpcNull, OpcPush, OpcDrop,   OpcDup, OpcSwap, OpcRot, OpcOver,   OpcAdd, OpcSub, OpcMul, OpcDiv,   OpcMod, OpcNeg, OpcAnd, OpcOr,   OpcXor, OpcNot, OpcShl, OpcShr,   OpcLAnd, OpcLOr, OpcLXor, OpcLNot,   OpcCat, OpcReM, OpcReIM, OpcReNm,   OpcReINm, OpcLike, OpcILike, OpcNLike,   OpcNIlike, OpcEq, OpcNe, OpcGt,   OpcLt, OpcGe, OpcLe, OpcCond,   OpcAs, OpcField, OpcFunc }
Public Member Functions
	ExpEvaluator (const TokenDict *operators=0)
	ExpEvaluator (Parser style)
	ExpEvaluator (const ExpEvaluator &original)
virtual	~ExpEvaluator ()
int	compile (const char *expr)
bool	evaluate (ObjList *results)
bool	evaluate (ObjList &results)
int	evaluate (NamedList &results, unsigned int index=0, const char *prefix=0)
int	evaluate (Array &results, unsigned int index)
bool	simplify ()
bool	null () const
String	dump () const
const TokenDict *	operators ()
ExpExtender *	extender () const
void	extender (ExpExtender *ext)
Protected Member Functions
char	skipWhites (const char *&expr) const
int	getKeyword (const char *str) const
bool	gotError (const char *error=0, const char *text=0)
virtual bool	runCompile (const char *&expr)
virtual Opcode	getOperator (const char *&expr) const
virtual const char *	getOperator (Opcode oper) const
virtual int	getPrecedence (Opcode oper)
virtual bool	getSeparator (const char *&expr, bool remove)
virtual bool	getOperand (const char *&expr)
virtual bool	getNumber (const char *&expr)
virtual bool	getString (const char *&expr)
virtual bool	getFunction (const char *&expr)
virtual bool	getField (const char *&expr)
void	addOpcode (Opcode oper)
void	addOpcode (const String &value)
void	addOpcode (long int value)
void	addOpcode (Opcode oper, const String &name, long int value=0)
ExpOperation *	popOne (ObjList &stack)
virtual bool	trySimplify ()
virtual bool	runEvaluate (ObjList &stack)
virtual bool	runOperation (ObjList &stack, const ExpOperation &oper)
virtual bool	runFunction (ObjList &stack, const ExpOperation &oper)
virtual bool	runField (ObjList &stack, const ExpOperation &oper)
Protected Attributes
const TokenDict *	m_operators
ObjList	m_opcodes

---

Detailed Description

An expression parser and evaluator.

A class used to build stack based (posifix) expression parsers and evaluators

---

Member Enumeration Documentation

enum Parser

Parsing styles

enum Opcode

Operation codes

---

Constructor & Destructor Documentation

ExpEvaluator

(

const TokenDict *

operators = 0

)

[explicit]

Constructs an evaluator from an operator dictionary

Parameters:

operators

Pointer to operator dictionary, longest strings first

ExpEvaluator

(

Parser

style

)

[explicit]

Constructs an evaluator from a parser style

Parameters:

style

Style of parsing to use

ExpEvaluator

(

const ExpEvaluator &

original

)

Copy constructor

Parameters:

original

Evaluator to copy the operation list from

virtual ~ExpEvaluator

(

)

[virtual]

Destructor

---

Member Function Documentation

int compile

(

const char *

expr

)

Parse and compile an expression

Parameters:

expr

Pointer to expression to compile

Returns:

Number of expressions compiled, zero on error

bool evaluate

(

ObjList *

results

)

Evaluate the expression, optionally return results

Parameters:

results

List to fill with results row

Returns:

True if expression evaluation succeeded, false on failure

bool evaluate

(

ObjList &

results

)

[inline]

Evaluate the expression, return computed results

Parameters:

results

List to fill with results row

Returns:

True if expression evaluation succeeded, false on failure

int evaluate	(	NamedList &	results,
		unsigned int	index = 0,
		const char *	prefix = 0
	)

Evaluate the expression, return computed results

Parameters:

	results	List of parameters to populate with results row
	index	Index of result row, zero to not include an index
	prefix	Prefix to prepend to parameter names

Returns:

Number of result columns, -1 on failure

int evaluate	(	Array &	results,
		unsigned int	index
	)

Evaluate the expression, return computed results

Parameters:

	results	Array of result rows to populate
	index	Index of result row, zero to just set column headers

Returns:

Number of result columns, -1 on failure

bool simplify

(

)

[inline]

Simplify the expression, performs constant folding

Returns:

True if the expression was simplified

bool null

(

)

const [inline]

Check if the expression is empty (no operands or operators)

Returns:

True if the expression is completely empty

String dump

(

)

const

Dump the postfix expression according to current operators dictionary

Returns:

String representation of operations

const TokenDict* operators

(

)

[inline]

Retrieve the internally used operator dictionary

Returns:

Pointer to operators dictionary in use

ExpExtender* extender

(

)

const [inline]

Retrieve the internally used expression extender

Returns:

Pointer to the extender in use, NULL if none

void extender

(

ExpExtender *

ext

)

Set the expression extender to use in evaluation

Parameters:

ext

Pointer to the extender to use, NULL to remove current

char skipWhites

(

const char *&

expr

)

const [protected]

Helper method to skip over whitespaces

Parameters:

expr

Pointer to expression cursor, gets advanced

Returns:

First character after whitespaces where expr points

int getKeyword

(

const char *

str

)

const [protected]

Helper method to count characters making a keyword

Parameters:

str

Pointer to text without whitespaces in front

Returns:

Length of the keyword, 0 if a valid keyword doesn't follow

bool gotError	(	const char *	error = 0,
		const char *	text = 0
	)			[protected]

Helper method to display debugging errors internally

Parameters:

	error	Text of the error
	text	Optional text that caused the error

Returns:

Always returns false

virtual bool runCompile

(

const char *&

expr

)

[protected, virtual]

Runs the parser and compiler for one (sub)expression

Parameters:

expr

Pointer to text to parse, gets advanced

Returns:

True if one expression was compiled and a separator follows

virtual Opcode getOperator

(

const char *&

expr

)

const [protected, virtual]

Returns next operator in the parsed text

Parameters:

expr

Pointer to text to parse, gets advanced if succeeds

Returns:

Operator code, OpcNone on failure

virtual const char* getOperator

(

Opcode

oper

)

const [protected, virtual]

Helper method to get the canonical name of an operator

Parameters:

oper

Operator code

Returns:

name of the operator, NULL if it doesn't have one

virtual int getPrecedence

(

Opcode

oper

)

[protected, virtual]

Get the precedence of an operator

Parameters:

oper

Operator code

Returns:

Precedence of the operator, zero (lowest) if unknown

virtual bool getSeparator	(	const char *&	expr,
		bool	remove
	)			[protected, virtual]

Check if we are at an expression separator and optionally skip past it

Parameters:

	expr	Pointer to text to check, gets advanced if asked to remove separator
	remove	True to skip past the found separator

Returns:

True if a separator was found

virtual bool getOperand

(

const char *&

expr

)

[protected, virtual]

Get an operand, advance parsing pointer past it

Parameters:

expr

Pointer to text to parse, gets advanced on success

Returns:

True if succeeded, must add the operand internally

virtual bool getNumber

(

const char *&

expr

)

[protected, virtual]

Get a numerical operand, advance parsing pointer past it

Parameters:

expr

Pointer to text to parse, gets advanced on success

Returns:

True if succeeded, must add the operand internally

virtual bool getString

(

const char *&

expr

)

[protected, virtual]

Get a string operand, advance parsing pointer past it

Parameters:

expr

Pointer to text to parse, gets advanced on success

Returns:

True if succeeded, must add the operand internally

virtual bool getFunction

(

const char *&

expr

)

[protected, virtual]

Get a function call, advance parsing pointer past it

Parameters:

expr

Pointer to text to parse, gets advanced on success

Returns:

True if succeeded, must add the operand internally

virtual bool getField

(

const char *&

expr

)

[protected, virtual]

Get a field keyword, advance parsing pointer past it

Parameters:

expr

Pointer to text to parse, gets advanced on success

Returns:

True if succeeded, must add the operand internally

void addOpcode

(

Opcode

oper

)

[protected]

Add a simple operator to the expression

Parameters:

oper

Operator code to add

void addOpcode

(

const String &

value

)

[protected]

Add a string constant to the expression

Parameters:

value

String value to add, will be pushed on execution

void addOpcode

(

long int

value

)

[protected]

Add an integer constant to the expression

Parameters:

value

Integer value to add, will be pushed on execution

void addOpcode	(	Opcode	oper,
		const String &	name,
		long int	value = 0
	)			[protected]

Add a function or field to the expression

Parameters:

	oper	Operator code to add, must be OpcField or OpcFunc
	name	Name of the field or function, case sensitive
	value	Numerical value used as parameter count to functions

ExpOperation* popOne

(

ObjList &

stack

)

[protected]

Pops an operand off the evaluation stack

Parameters:

stack

Evaluation stack to remove the operand from

Returns:

Operator removed from stack, NULL if stack underflow

virtual bool trySimplify

(

)

[protected, virtual]

Try to apply simplification to the expression

Returns:

True if the expression was simplified

virtual bool runEvaluate

(

ObjList &

stack

)

[protected, virtual]

Try to evaluate the expression

Parameters:

stack

Evaluation stack in use, results are left on stack

Returns:

True if evaluation succeeded

virtual bool runOperation	(	ObjList &	stack,
		const ExpOperation &	oper
	)			[protected, virtual]

Try to evaluate a single operation

Parameters:

	stack	Evaluation stack in use, operands are popped off this stack and results are pushed back on stack
	oper	Operation to execute

Returns:

True if evaluation succeeded

virtual bool runFunction	(	ObjList &	stack,
		const ExpOperation &	oper
	)			[protected, virtual]

Try to evaluate a single function

Parameters:

	stack	Evaluation stack in use, parameters are popped off this stack and results are pushed back on stack
	oper	Function to evaluate

Returns:

True if evaluation succeeded

virtual bool runField	(	ObjList &	stack,
		const ExpOperation &	oper
	)			[protected, virtual]

Try to evaluate a single field

Parameters:

	stack	Evaluation stack in use, field value must be pushed on it
	oper	Field to evaluate

Returns:

True if evaluation succeeded

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Member Data Documentation

const TokenDict* m_operators [protected]

Internally used operator dictionary

ObjList m_opcodes [protected]

Internally used list of operands and operator codes

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The documentation for this class was generated from the following file:

• yateclass.h