com.hp.hpl.jena.graph.query
Class Expression.Base

java.lang.Object
  extended bycom.hp.hpl.jena.graph.query.Expression.Base
All Implemented Interfaces:
Expression
Direct Known Subclasses:
Expression.Application, Expression.BoolConstant, Expression.Literal, Expression.Variable
Enclosing class:
Expression

public abstract static class Expression.Base
extends java.lang.Object
implements Expression

An abstract base class for Expressions; over-ride as appropriate. The sub-classes may be more useful. Base provides an implementation of prepare which produces a slow Valuator that relies on the Base's evalBool.


Nested Class Summary
 
Nested classes inherited from class com.hp.hpl.jena.graph.query.Expression
Expression.Application, Expression.Base, Expression.BoolConstant, Expression.Literal, Expression.Util, Expression.Valof, Expression.Variable
 
Field Summary
 
Fields inherited from interface com.hp.hpl.jena.graph.query.Expression
FALSE, TRUE
 
Constructor Summary
Expression.Base()
           
 
Method Summary
 int argCount()
          If this Expression is an application, answer the number of arguments that it has.
 Expression getArg(int i)
          If this Expression is an application, and 0 <= i < argCount(), answer the ith argument.
 java.lang.String getFun()
          If this Expression is an application, return the string identifying the function, which should be a URI.
 java.lang.String getName()
          If this Expression is a variable, answer a [non-null] String which is its name.
 java.lang.Object getValue()
          If this Expression is a literal, answer the value of that literal.
 boolean isApply()
          Answer true iff this Expression represents the application of some function [or operator] to some arguments [or operands].
 boolean isLiteral()
          Answer true iff this Expression represents a literal [Java object] value.
 boolean isVariable()
          Answer true iff this Expression represents a variable.
 Valuator prepare(VariableIndexes vi)
          Answer a Valuator which does the same evaluation as this Expression when supplied with a mapping from variable indexes to their values.
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface com.hp.hpl.jena.graph.query.Expression
evalBool
 

Constructor Detail

Expression.Base

public Expression.Base()
Method Detail

isVariable

public boolean isVariable()
Description copied from interface: Expression
Answer true iff this Expression represents a variable.

Specified by:
isVariable in interface Expression

isApply

public boolean isApply()
Description copied from interface: Expression
Answer true iff this Expression represents the application of some function [or operator] to some arguments [or operands].

Specified by:
isApply in interface Expression

isLiteral

public boolean isLiteral()
Description copied from interface: Expression
Answer true iff this Expression represents a literal [Java object] value.

Specified by:
isLiteral in interface Expression

getName

public java.lang.String getName()
Description copied from interface: Expression
If this Expression is a variable, answer a [non-null] String which is its name. Otherwise the behaviour is unspecified.

Specified by:
getName in interface Expression

getValue

public java.lang.Object getValue()
Description copied from interface: Expression
If this Expression is a literal, answer the value of that literal. Otherwise the behaviour is unspecified.

Specified by:
getValue in interface Expression

argCount

public int argCount()
Description copied from interface: Expression
If this Expression is an application, answer the number of arguments that it has. Otherwise the behaviour is unspecified.

Specified by:
argCount in interface Expression

getFun

public java.lang.String getFun()
Description copied from interface: Expression
If this Expression is an application, return the string identifying the function, which should be a URI. Otherwise the behaviour is unspecified.

Specified by:
getFun in interface Expression

getArg

public Expression getArg(int i)
Description copied from interface: Expression
If this Expression is an application, and 0 <= i < argCount(), answer the ith argument. Otherwise the behaviour is unspecified.

Specified by:
getArg in interface Expression

prepare

public Valuator prepare(VariableIndexes vi)
Description copied from interface: Expression
Answer a Valuator which does the same evaluation as this Expression when supplied with a mapping from variable indexes to their values. The composition of the variable->index map vi and the index->value map given to the valuator is equivalent to the VariableValues map that would be supplied to evalBool.

Specified by:
prepare in interface Expression


Copyright © 2000-2003 Hewlett-Packard. All Rights Reserved.