nars.language
Class Variable

java.lang.Object
  nars.language.Term
      nars.language.Variable

All Implemented Interfaces:

java.lang.Cloneable, java.lang.Comparable<Term>

public class Variable
extends Term

A variable term, which does not correspond to a concept

Nested Class Summary

static class

Variable.VarType Four variable types plus a wild card

Field Summary

private CompoundTerm	scope The minimum CompoundTerm what contains all occurences of this variable
private Variable.VarType	type Type of the variable

Fields inherited from class nars.language.Term

name

Constructor Summary

	Variable(java.lang.String s) Constructor, from a given variable name
private	Variable(java.lang.String n, Variable.VarType t, CompoundTerm s) Constructor, with all fields

Method Summary

java.lang.Object	clone() Clone a Variable
boolean	equals(java.lang.Object that) Whether this variable equals another one
static java.util.HashMap<java.lang.String,Term>	findSubstitute(Variable.VarType type, Term term1, Term term2) To find a substitution that can unify two Terms without changing them
private static java.util.HashMap<java.lang.String,Term>	findSubstitute(Variable.VarType type, Term term1, Term term2, java.util.HashMap<java.lang.String,Term> subs) To recursively find a substitution that can unify two Terms without changing them
private static java.util.HashMap<java.lang.String,Term>	findSubstituteVar(Variable.VarType type, Variable var, Term term, java.util.HashMap<java.lang.String,Term> subs, boolean first) To find a substitution that can unify a Vriable and a Term
java.lang.String	getConstantName() Variable name is omitted in sorting
java.lang.String	getName() Get variable name with dependency list (if any)
java.lang.String	getStoredName() Get variable name without dependency list (if any)
Variable.VarType	getType() Get the type of the variable
java.lang.String	getVarName(boolean first) Rename a variable temporally to distinguish it from variables in other Terms
int	hashCode() Get a hash code for the variable
boolean	isConstant() A variable is constant
static boolean	match(Variable.VarType type1, Variable.VarType type2) Whether two variable types can match each other in unification
void	setName(java.lang.String n) Rename the variable
void	setScope(CompoundTerm t) Set the scope of the variable
static boolean	unify(Variable.VarType type, Term t1, Term t2, Term compound1, Term compound2) To unify two Terms, then apply the substitution to the two compounds

Methods inherited from class nars.language.Term

compareTo, getComplexity, getOrder, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

type

private Variable.VarType type

Type of the variable

scope

private CompoundTerm scope

The minimum CompoundTerm what contains all occurences of this variable

Constructor Detail

Variable

public Variable(java.lang.String s)

Constructor, from a given variable name

Parameters:

s - A String read from input

Variable

private Variable(java.lang.String n,
                 Variable.VarType t,
                 CompoundTerm s)

Constructor, with all fields

Parameters:

n - Variable name

s - Variable scope

t - Variable type

Method Detail

clone

public java.lang.Object clone()

Clone a Variable

Overrides:

clone in class Term

Returns:

The cloned Variable

getConstantName

public java.lang.String getConstantName()

Variable name is omitted in sorting

Overrides:

getConstantName in class Term

Returns:

The Variable prefix

getVarName

public java.lang.String getVarName(boolean first)

Rename a variable temporally to distinguish it from variables in other Terms

Parameters:

first - Whether it is the first term

Returns:

The new name

setName

public void setName(java.lang.String n)

Rename the variable

Parameters:

n - The new name

getType

public Variable.VarType getType()

Get the type of the variable

Returns:

The variable type

setScope

public void setScope(CompoundTerm t)

Set the scope of the variable

Parameters:

t - The new scope

equals

public boolean equals(java.lang.Object that)

Whether this variable equals another one

Overrides:

equals in class Term

Parameters:

that - The other variable

Returns:

Whether the two are equal

hashCode

public int hashCode()

Get a hash code for the variable

Overrides:

hashCode in class Term

Returns:

The hash code

getStoredName

public java.lang.String getStoredName()

Get variable name without dependency list (if any)

Returns:

The stored name

getName

public java.lang.String getName()

Get variable name with dependency list (if any)

Overrides:

getName in class Term

Returns:

The generated name

isConstant

public boolean isConstant()

A variable is constant

Overrides:

isConstant in class Term

Returns:

false

match

public static boolean match(Variable.VarType type1,
                            Variable.VarType type2)

Whether two variable types can match each other in unification

Parameters:

type1 - Type of the first variable

type2 - Type of the second variable

Returns:

The matching result

unify

public static boolean unify(Variable.VarType type,
                            Term t1,
                            Term t2,
                            Term compound1,
                            Term compound2)

To unify two Terms, then apply the substitution to the two compounds

Parameters:

type - The type of Variable to be unified

t1 - The first Term to be unified

t2 - The second Term to be unified

compound1 - The first compound to be substituted

compound2 - The second compound to be substituted

Returns:

Whether a unification has been succeeded

findSubstitute

public static java.util.HashMap<java.lang.String,Term> findSubstitute(Variable.VarType type,
                                                                      Term term1,
                                                                      Term term2)

To find a substitution that can unify two Terms without changing them

Parameters:

type - The type of Variable to be substituted

term1 - The first Term to be unified

term2 - The second Term to be unified

Returns:

The substitution that unifies the two Terms

findSubstitute

private static java.util.HashMap<java.lang.String,Term> findSubstitute(Variable.VarType type,
                                                                       Term term1,
                                                                       Term term2,
                                                                       java.util.HashMap<java.lang.String,Term> subs)

To recursively find a substitution that can unify two Terms without changing them

Parameters:

type - The type of Variable to be substituted

term1 - The first Term to be unified

term2 - The second Term to be unified

subs - The substitution formed so far

Returns:

The substitution that unifies the two Terms

findSubstituteVar

private static java.util.HashMap<java.lang.String,Term> findSubstituteVar(Variable.VarType type,
                                                                          Variable var,
                                                                          Term term,
                                                                          java.util.HashMap<java.lang.String,Term> subs,
                                                                          boolean first)

To find a substitution that can unify a Vriable and a Term

Parameters:

type - The type of Variable to be substituted

var - The Variable to be unified

term - The Term to be unified

subs - The substitution formed so far

first - If it is the first Term in unify

Returns:

The substitution that unifies the two Terms, as "name-term" pairs