org.esa.snap.core.jexp

Interface Function

public interface Function

A representation of a function. A function has a name, a return type and can be evaluated by passing a number of arguments to it.

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

Version:

$Revision$ $Date$

Method Summary

Modifier and Type	Method and Description
boolean	evalB(EvalEnv env, Term[] args) Evaluates this function to a boolean value.
double	evalD(EvalEnv env, Term[] args) Evaluates this function to a double value.
int	evalI(EvalEnv env, Term[] args) Evaluates this function to an int value.
int	getArgType(int argIndex) Gets the type of a function's i-th argument.
String	getName() Gets the function's name.
int	getNumArgs() Gets the function's number of arguments.
int	getRetType() Gets the function's return type.
boolean	isConst(Term[] args)

Method Detail

getName

String getName()

Gets the function's name.

Returns:

the name, should never be null.

getRetType

int getRetType()

Gets the function's return type.

Returns:

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

getNumArgs

int getNumArgs()

Gets the function's number of arguments.

Returns:

number of arguments.

getArgType

int getArgType(int argIndex)

Gets the type of a function's i-th argument.

Parameters:

argIndex - The argument index.

Returns:

an arry of types, each element should always be one of the TYPE_X constants defined in the Term class.

evalB

boolean evalB(EvalEnv env,
              Term[] args)
       throws EvalException

Evaluates this function to a boolean value.

Parameters:

env - the application dependant environment.

args - the (un-evaluated) arguments passed to the function

Returns:

a boolean value

Throws:

EvalException - if the evaluation fails

evalI

int evalI(EvalEnv env,
          Term[] args)
   throws EvalException

Evaluates this function to an int value.

Parameters:

env - the application dependant environment.

args - the (un-evaluated) arguments passed to the function

Returns:

an int value

Throws:

EvalException - if the evaluation fails

evalD

double evalD(EvalEnv env,
             Term[] args)
      throws EvalException

Evaluates this function to a double value.

Parameters:

env - the application dependant environment.

args - the (un-evaluated) arguments passed to the function

Returns:

a double value

Throws:

EvalException - if the evaluation fails

isConst

boolean isConst(Term[] args)

Returns:

true, if this symbol has a constant value with respect to the given arguments and to any EvalEnv, including null.