Inherits org.qscript.Token.

Public Member Functions
	Operator (String symbol, int nbrArgs, int priority, int type)

abstract Argument	resolve (Script script, Token token, Argument[] args, Object...objects) throws EvaluationException

String	getSymbol ()

int	getNbrArgs ()

int	getPriority ()

int	getOpType ()

boolean	isOperator ()

String	forListing ()

String	toString ()

Public Member Functions inherited from org.qscript.Token
void	setTextPosition (int charStart, int charWidth)

void	setTextPosition (int line, int charStart, int charWidth)

int	getLine ()

int	getCharStart ()

int	getCharWidth ()

boolean	isArgument ()

boolean	isFlowAction ()

boolean	isVariable ()

boolean	isThing ()

boolean	isOperator ()

boolean	isFlowOperator ()

String	forListing ()

Static Public Attributes
static final int	MARKER = 0

static final int	CONSTANT = 1

static final int	INFIX_SYMBOL = 2

static final int	FUNCTION = 3

Static Public Attributes inherited from org.qscript.Token
static final Token	DUMMY = new Argument(null)

Protected Member Functions
boolean	testForUninitialisedVars (Script script, Argument[] args) throws EvaluationException

boolean	testForUninitialisedVar (Script script, Argument arg) throws EvaluationException

void	handleInvalidArguments (Script script, Token token) throws EvaluationException

Protected Member Functions inherited from org.qscript.Token
	Token ()

Additional Inherited Members
Protected Attributes inherited from org.qscript.Token
int	line

int	charStart

int	charWidth

Detailed Description

This is the base class for all operators to be recognized by the expression parser.
There are four operator types -
MARKER
These do not perform any evaluation themselves so they do not require any arguments. Examples include WEND, ELSE, comma, parenthesis.
CONSTANT
These are simply named values (e.g. PI, E, EOL) so they have no arguments to process but must have a high priority (40) so that its value is retrieved before further evaluation.
INFIX_SYMBOL
An infix symbols is any symbol that sits between the two operands it has to process. These include the

normal mathematical operators such as + = / *
assignment operator =
the logical operators && AND || OR
comparison operators such as == > <= !=

It does mean that infix symbols always require exactly two arguments.
FUNCTION
A function is any symbol that takes one or more arguments and evaluates them. All functions have the format

symbol(comma separated list of arguments)

These include all the common mathematical functions such as sqrt, cos, sin; but the library also has some extras such as rnd, pow
All functions have the same priority (30)

It is possible to create user defined operators and add them to the standard set.

Author: Peter Lager

Constructor & Destructor Documentation

org.qscript.operator.Operator.Operator	(	String	symbol,
		int	nbrArgs,
		int	priority,
		int	type
	)

This is the constructor used to create an operator object.

Parameters

symbol	the symbol/name that identifies this operator.
nbrArgs	the number of arguments needed by this operator
priority	the value used to determine the order of precedence
type	the operator type

Member Function Documentation

String org.qscript.operator.Operator.forListing ( )

Used in Script and Parser classes when listings

int org.qscript.operator.Operator.getNbrArgs ( )

Get the number of arguments needed by this operator

int org.qscript.operator.Operator.getOpType ( )

Get the operator type

int org.qscript.operator.Operator.getPriority ( )

Get the operator priority value. This is used to determine the order that operators are evaluated.

String org.qscript.operator.Operator.getSymbol ( )

Get the operator identifying symbol

void org.qscript.operator.Operator.handleInvalidArguments	(	Script	script,
		Token	token
	)		throws EvaluationException

protected

Call this method if the arguments are the incorrect types for the operator

Parameters

script	the Script object responsible for evaluation
charNo
charWidth

Exceptions

EvaluationException

boolean org.qscript.operator.Operator.isOperator ( )

Returns true

abstract Argument org.qscript.operator.Operator.resolve	(	Script	script,
		Token	token,
		Argument[]	args,
		Object...	objects
	)		throws EvaluationException

pure virtual

Parameters

script	the Script object responsible for evaluation
token	the current token being evaluated
args	the arguments for this operator
objects	ignore it has been included for possible future use

Returns: the result of this operation or null if there is no need to store the result

Exceptions

SyntaxException
EvaluationException

boolean org.qscript.operator.Operator.testForUninitialisedVar	(	Script	script,
		Argument	arg
	)		throws EvaluationException

protected

This method checks to see if a variable has been initialized.

Parameters

script	the Script object responsible for evaluation
args	list of Arguments to check

Returns: true if the variable has been initialized

Exceptions

SyntaxException
EvaluationException

boolean org.qscript.operator.Operator.testForUninitialisedVars	(	Script	script,
		Argument[]	args
	)		throws EvaluationException

protected

This method checks for uninitialized variables and should be called by the first statement in the method resolve().

The only exception is the Assignment class where the left hand operand may be an uninitialized variable.

Parameters

script	the Script object responsible for evaluation
args	list of Arguments to check

Exceptions

SyntaxException
EvaluationException

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

/Users/peter/git/qscript-repos/Q-script/src/org/qscript/operator/Operator.java

Public Member Functions

Static Public Attributes

Protected Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation