org.esa.snap.core.jexp

Interface Symbol

All Known Subinterfaces:

Variable

All Known Implementing Classes:

RasterDataSymbol, SingleFlagSymbol

public interface Symbol

Represents a read-only symbol. A symbol can be a named constant or variable. It has a return type an can be evaluated.

Within an expression, a reference to a symbol is created if the parser encounters a name and this name can be resolved through the parser's current namespace. The resulting term in this case is an instance of Term.Ref.

Version:

$Revision$ $Date$

Method Summary

Modifier and Type	Method and Description
boolean	evalB(EvalEnv env) Evaluates this symbol to a boolean value.
double	evalD(EvalEnv env) Evaluates this symbol to a double value.
int	evalI(EvalEnv env) Evaluates this symbol to an int value.
String	evalS(EvalEnv env) Evaluates this symbol to a String value.
String	getName() Gets the symbol's name.
int	getRetType() Gets the symbol's return type.
boolean	isConst()

Method Detail

getName

String getName()

Gets the symbol's name.

Returns:

the name, should never be null

getRetType

int getRetType()

Gets the symbol's return type.

Returns:

the type, should always be one of the TYPE_X constants defined in the Term class.

evalB

boolean evalB(EvalEnv env)
       throws EvalException

Evaluates this symbol to a boolean value.

Parameters:

env - the application dependant environment.

Returns:

a boolean value

Throws:

EvalException - if the evaluation fails

evalI

int evalI(EvalEnv env)
   throws EvalException

Evaluates this symbol to an int value.

Parameters:

env - the application dependant environment.

Returns:

an int value

Throws:

EvalException - if the evaluation fails

evalD

double evalD(EvalEnv env)
      throws EvalException

Evaluates this symbol to a double value.

Parameters:

env - the application dependant environment.

Returns:

a double value

Throws:

EvalException - if the evaluation fails

evalS

String evalS(EvalEnv env)
      throws EvalException

Evaluates this symbol to a String value.

Parameters:

env - the application dependant environment.

Returns:

a double value

Throws:

EvalException - if the evaluation fails

isConst

boolean isConst()

Returns:

true, if this symbol has a constant value with respect to any EvalEnv, even null.