edu.mit.ai.psg.jeva
Interface IExpressionNode

All Known Subinterfaces:

IExpressionStoreNode

All Known Implementing Classes:

ExpressionNode

public abstract interface IExpressionNode

extends IJevaNode

Interface to nodes for Java expressions. Nodes should not call this interface directly, but instead use EvalMethods to capture errors into an EvalErrException.

Author:

CarlManning, caroma@ai.mit.edu
Copyright (c) 1997, 1998 Massachusetts Institute of Technology

See Also:

EvalMethods, ExpressionNode

Method Summary

IClass	getType() Returns cached type of verified expression [verifying calls getType(IEnv)].
IClass	getType(IEnv env) Verifies the type correctness of the expression and returns the static type of the expression (nodes should not call this interface directly).
Object	getValue(IEnv env) Get the value of this node (nodes should not call this interface directly).
boolean	isConstant(IEnv env) Predicate testing whether this is a constant expression (nodes should not call this interface directly).

Methods inherited from interface edu.mit.ai.psg.jeva.IJevaNode

getBeginToken, getEndToken, insertNewChildAfter, insertNewChildAt, insertNewChildBefore, jjtAccept, jnGetChild, jnGetParent, print, print, printToString, printToString, removeChild, replaceChild, replaceChild, setBeginToken, setEndToken

Methods inherited from interface edu.mit.ai.psg.jeva.Node

jjtAddChild, jjtClose, jjtGetChild, jjtGetNumChildren, jjtGetParent, jjtOpen, jjtSetParent

Method Detail

getType

public IClass getType(IEnv env)
               throws VerifyingException

Verifies the type correctness of the expression and returns the static type of the expression (nodes should not call this interface directly). Value may be cached.

Parameters:

env - environment of name bindings, etc.

Throws:

VerifyingException - if expression is illegal

See Also:

EvalMethods.getType(IExpressionNode, IEnv)

getType

public IClass getType()
               throws IllegalStateException

Returns cached type of verified expression [verifying calls getType(IEnv)].

Throws:

IllegalStateException - if not verified.

isConstant

public boolean isConstant(IEnv env)
                   throws VerifyingException

Predicate testing whether this is a constant expression (nodes should not call this interface directly). Value may be cached. This predicate is sometimes required for determining type (see [JavaLangSpec sec 15.27, 5.2, 15.24, 14.9])

Parameters:

env - environment of name bindings, etc.

Throws:

VerifyingException - if expression is illegal

See Also:

EvalMethods.isConstant(IExpressionNode, IEnv)

getValue

public Object getValue(IEnv env)
                throws ThrowException

Get the value of this node (nodes should not call this interface directly). Value may be cached if it is constant.

Parameters:

env - environment of name bindings, etc.

Throws:

ThrowException - if completes abruptly with an exception

See Also:

EvalMethods.eval(IExpressionNode, IEnv)