Package net.hydromatic.morel.util

Class Unifier.Variable

java.lang.Object

net.hydromatic.morel.util.Unifier.Variable

All Implemented Interfaces:

Comparable<Unifier.Variable>, Unifier.Term

Enclosing class:

Unifier

public static final class Unifier.Variable
extends Object
implements Unifier.Term, Comparable<Unifier.Variable>

A variable that represents a symbol or a sequence; unification's task is to find the substitutions for such variables.

Field Summary

Fields

Modifier and Type	Field	Description
(package private) final String	name
(package private) final int	ordinal

Constructor Summary

Constructors

Constructor	Description
Variable(int ordinal)	Creates a variable with an ordinal.
Variable(String name)	Creates a variable with a name.
Variable(String name, int ordinal)

Method Summary

Modifier and Type	Method	Description
<R> R	accept(Unifier.TermVisitor<R> visitor)
Unifier.Term	apply(Map<Unifier.Variable,Unifier.Term> substitutions)
void	checkCycle(Map<Unifier.Variable,Unifier.Term> map, Map<Unifier.Variable,Unifier.Variable> active)	Throws CycleException if expanding this term leads to a cycle.
int	compareTo(Unifier.Variable o)
boolean	contains(Unifier.Variable variable)
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

name

final String name

ordinal

final int ordinal

Constructor Details

Variable

Variable(String name,
 int ordinal)

Variable

Variable(String name)

Creates a variable with a name. The name must not be like "T0" or "T123", because those are the names created for variables with ordinals.

Variable

Variable(int ordinal)

Creates a variable with an ordinal. If the ordinal is "34" the name will be "T34". The ordinal must be non-negative.

Method Details

toString

public String toString()

Overrides:

toString in class Object

compareTo

public int compareTo(Unifier.Variable o)

Specified by:

compareTo in interface Comparable<Unifier.Variable>

apply

public Unifier.Term apply(Map<Unifier.Variable,Unifier.Term> substitutions)

Specified by:

apply in interface Unifier.Term

contains

public boolean contains(Unifier.Variable variable)

Specified by:

contains in interface Unifier.Term

checkCycle

public void checkCycle(Map<Unifier.Variable,Unifier.Term> map,
 Map<Unifier.Variable,Unifier.Variable> active)
                throws Unifier.CycleException

Description copied from interface: Unifier.Term

Throws CycleException if expanding this term leads to a cycle.

Specified by:

checkCycle in interface Unifier.Term

Throws:

Unifier.CycleException

accept

public <R> R accept(Unifier.TermVisitor<R> visitor)

Specified by:

accept in interface Unifier.Term