JavaRes/src/atp/Term.java at master · eprover/JavaRes · GitHub

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A simple implementation of first-order terms.

This program is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program ; if not, write to the Free Software

Foundation, Inc., 59 Temple Place, Suite 330, Boston,

MA 02111-1307 USA

package atp;

import java.io.*;

import java.util.*;

import java.text.*;

/** ***************************************************************

A composite term f(t1, ..., tn) is represented by the list

[f lt1, ..., ltn], where lt1, ..., ltn are lists representing the

subterms.

"X" -> "X"

"g(X, f(Y))" -> ["g", "X", ["f", "Y"]]

"g(a,b)" -> ["g", ["a"], ["b"]]

public class Term {

public String t = ""; // lowercase is a constant, uppercase is a variable

public ArrayList<Term> subterms = new ArrayList<Term>(); // empty if not composite

/** ***************************************************************

public Term() {

}

/** ***************************************************************

public Term(String op, Term t1, Term t2) {

t = op;

subterms.add(t1);

subterms.add(t2);

}

/** ***************************************************************

* @param s An input Object, expected to be a String.

* @return true if s == null or s is an empty String, else false.

public static boolean emptyString(Object s) {

return ((s == null) ||

((s instanceof String) && s.equals("")));

}

/** ***************************************************************

public String toString() {

StringBuffer result = new StringBuffer();

result.append(t);

if (subterms.size() > 0) {

result.append('(');

for (int i = 0; i < subterms.size(); i++) {

result.append(subterms.get(i).toString());

if (i < subterms.size()-1)

result.append(", ");

}

result.append(')');

}

return result.toString();

}

/** ***************************************************************

public String toKIFString() {

StringBuffer result = new StringBuffer();

if (subterms.size() > 0)

result.append('(');

result.append(t);

if (subterms.size() > 0) {

result.append(" ");

for (int i = 0; i < subterms.size(); i++) {

result.append(subterms.get(i).toString());

if (i < subterms.size()-1)

result.append(" ");

}

if (subterms.size() > 0)

result.append(')');

return result.toString();

}

/** ***************************************************************

public Term parseTermList(Lexer lex) {

try {

//System.out.println("in Term.parseTermList(): " + lex.literal);

Term newT = new Term();

subterms.add(newT.parse(lex));

lex.next();

while (lex.literal.equals(",")) {

newT = new Term();

subterms.add(newT.parse(lex));

lex.next();

//System.out.println("in Term.parseTermList(): next token: " + lex.literal);

}

return this;

}

catch (Exception ex) {

System.out.println("Error in Term.parseTermList(): " + ex.getMessage());

System.out.println("Error in Term.parseTermList(): token:" + lex.literal);

ex.printStackTrace();

}

return null;

}

/** ***************************************************************

* This routine expects the tokenizer to be set before the starting token.

* A term is either a variable or a function, where a function can have

* 0 arguments, and therefore be just a constant.

public Term parse(Lexer lex) {

try {

//System.out.println("INFO in Term.parse(): before next token: " + lex.literal);

lex.next();

//if (!lex.type.equals(Lexer.IdentLower) && !lex.type.equals(Lexer.IdentUpper))

//lex.next();

//System.out.println("INFO in Term.parse(): after next token: " + lex.literal);

if (!lex.type.equals(Lexer.IdentLower) && !lex.type.equals(Lexer.IdentUpper) &&

!lex.type.equals(Lexer.DefFunctor) && !lex.type.equals(Lexer.QuotedString) &&

!lex.type.equals(Lexer.Number))

throw new ParseException("Error in Term.parse(): Expected a word. Found " +

lex.literal + " " + lex.type,lex.input.getLineNumber());

if (lex.type.equals(Lexer.IdentUpper)) {

t = lex.literal;

return this;

}

else {

if (lex.type.equals(Lexer.IdentLower)) {

//System.out.println("lower case term: " + lex.literal);

t = lex.literal;

if (lex.look().equals("(")) {

lex.next();

parseTermList(lex);

if (!lex.literal.equals(")"))

throw new ParseException("Error in Term.parse(): Close paren expected. Found " +

lex.literal + " " + lex.type,lex.input.getLineNumber());

//System.out.println("INFO in Term.parse(): got close paren: " + lex.literal);

return this;

}

else {

return this;

}

else {

// if (lex.literal.equals("$false"))

if (lex.type.equals(Lexer.DefFunctor) || lex.type.equals(Lexer.QuotedString) ||

lex.type.equals(Lexer.Number))

t = lex.literal;

else

if (lex.type == Lexer.EOFToken)

return this;

else

throw new ParseException("Error in Term.parse(): Identifier " + lex.literal + " with type " + lex.type +

" doesn't start with upper or lower case letter.",lex.input.getLineNumber());

}

catch (ParseException ex) {

if (lex.literal == lex.EOFToken)

return this;

System.out.println("Error in Term.parse(): " + ex.getMessage());

System.out.println("Error in Term.parse(): word token:" + lex.literal);

System.out.println("encountered at line: " + ex.getErrorOffset());

System.out.println("in file: " + lex.filename);

ex.printStackTrace();

}

return this;

}

/** ***************************************************************

public static Term string2Term(String s) {

Term t = new Term();

Lexer lex = new Lexer(s);

return t.parse(lex);

}

/** ***************************************************************

* Check if the term is a variable. This assumes that t is a

* well-formed term.

public boolean isVar() {

return Character.isUpperCase(t.charAt(0));

}

/** ***************************************************************

* Check if the term is a compound term. This assumes that t is a

* well-formed term.

public boolean isCompound() {

return !isVar();

}

/** ***************************************************************

* Return True if term has no variables, False otherwise

public boolean isGround() {

if (!Term.emptyString(t) && Character.isUpperCase(t.charAt(0)))

return false;

for (int i = 0; i < subterms.size(); i++)

if (!subterms.get(i).isGround())

return false;

return true;

}

/** ***************************************************************

public ArrayList<Term> collectVars() {

ArrayList<Term> result = new ArrayList<Term>();

if (isVar())

result.add(this);

for (int i = 0; i < subterms.size(); i++) {

ArrayList<Term> newvars = subterms.get(i).collectVars();

for (Term newv : newvars) {

if (!result.contains(newv))

result.add(newv);

}

return result;

}

/** ***************************************************************

* Return all function symbols

public ArrayList<String> collectFuns() {

ArrayList<String> res = new ArrayList<String>();

if (isCompound()) {

res.add(t);

for (Term s : subterms) {

ArrayList<String> newfuns = s.collectFuns();

for (String news : newfuns) {

if (!res.contains(news))

res.add(news);

}

return res;

}

/** ***************************************************************

public ArrayList<String> getConstantStrings() {

ArrayList<String> result = new ArrayList<String>();

if (Character.isLowerCase(t.charAt(0)))

result.add(t);

for (int i = 0; i < subterms.size(); i++) {

ArrayList<String> temp = subterms.get(i).getConstantStrings();

if (temp != null)

result.addAll(temp);

}

return result;

}

/** ***************************************************************

public String getFunc() {

return t;

}

/** ***************************************************************

public ArrayList<Term> getArgs() {

return subterms;

}

/** ***************************************************************

* Insert all function symbols and their associated arities in t into

* the signature

public Signature collectSig(Signature sig) {

if (isCompound()) {

sig.addFun(getFunc(), subterms.size());

for (Term s:getArgs())

sig = s.collectSig(sig);

}

return sig;

}

/** ***************************************************************

* Return the weight of the term, counting fweight for each function symbol

* occurrence, vweight for each variable occurrence. Examples:

* termWeight(f(a,b), 1, 1) = 3

* termWeight(f(a,b), 2, 1) = 6

* termWeight(f(X,Y), 2, 1) = 4

* termWeight(X, 2, 1) = 1

* termWeight(g(a), 3, 1) = 6

public int weight(int fweight, int vweight) {

int total = 0;

if (Character.isUpperCase(t.charAt(0)))

total = vweight;

else

total = fweight;

for (int i = 0; i < subterms.size(); i++)

total = total + subterms.get(i).weight(fweight,vweight);

return total;

}

/** ***************************************************************

* Return the subterm of t at position pos (or None if pos is not a

* position in term). pos is a list of integers denoting branches, e.g.

* subterm(f(a,b), []) = f(a,b)

* subterm(f(a,g(b)), [0]) = a

* subterm(f(a,g(b)), [1]) = g(b)

* subterm(f(a,g(b)), [1,0]) = b

* subterm(f(a,g(b)), [3,0]) = None

* Note that pos will be destroyed.

public Term subterm(ArrayList<Integer> pos) {

if (pos.size() == 0)

return this;

int index = pos.remove(0).intValue();

if (index >= subterms.size())

return null;

if (pos.size() == 0)

return subterms.get(index);

else

return subterms.get(index).subterm(pos);

}

/** ***************************************************************

@Override public boolean equals(Object other_obj) {

//System.out.println("Term.equals(): term: " + this + " other: " + other_obj);

//if (other_obj == null) {

// System.out.println("Term.equals() argument is null");

// return false;

//}

// if (!other_obj.getClass().getName().equals("Term")) {

// System.out.println("Term.equals() passed object not of type Term");

// return false;

// }

Term t2 = (Term) other_obj;

//System.out.println("INFO in Term.equals(): term:" + this + " other: " + other_obj);

if (!t2.t.equals(t))

return false;

if (t2.subterms.size() != subterms.size())

return false;

for (int i = 0; i < subterms.size(); i++)

if (!subterms.get(i).equals(t2.subterms.get(i)))

return false;

return true;

}

/** ***************************************************************

@Override public int hashCode() {

int total = 0;

// if (negated)

// total = 1;

if (subterms.size() < 1)

return total + t.hashCode() * 2;

else {

for (int i = 0; i < subterms.size(); i++)

total = total + subterms.get(i).hashCode();

return total;

}

/** ***************************************************************

public Term deepCopy() {

Term result = new Term();

result.t = t;

for (int i = 0; i < subterms.size(); i++)

result.subterms.add(subterms.get(i).deepCopy());

return result;

}

/** ***************************************************************

* ************ UNIT TESTS *****************

* Set up test content.

String example1 = "X";

String example2 = "a";

String example3 = "g(a,b)";

String example4 = "g(X, f(Y))";

String example5 = "g(X, f(Y))";

String example6 = "f(X,g(a,b))";

String example7 = "g(X)";

String example8 = "g(b,b)";

Term t1 = null;

Term t2 = null;

Term t3 = null;

Term t4 = null;

Term t5 = null;

Term t6 = null;

Term t7 = null;

Term t8 = null;

/** ***************************************************************

* Set up test content.

public void setupTests() {

t1 = string2Term(example1);

t2 = string2Term(example2);

t3 = string2Term(example3);

t4 = string2Term(example4);

t5 = string2Term(example5);

t6 = string2Term(example6);

t7 = string2Term(example7);

t8 = string2Term(example8);

}

/** ***************************************************************

* Test that parse() is working properly

public void parseTest() {

System.out.println("---------------------");

System.out.println("INFO in parseTest()");

System.out.println(t1 + " = " + example1);

System.out.println(t2 + " = " + example2);

System.out.println(t3 + " = " + example3);

System.out.println(t4 + " = " + example4);

System.out.println(t5 + " = " + example5);

System.out.println(t6 + " = " + example6);

System.out.println(t7 + " = " + example7);

System.out.println(t8 + " = " + example8);

}

/** ***************************************************************

* Test that parse() and toString() are dual. Start with terms,

* so that we are sure to get the canonical string representation.

public void testToString() {

System.out.println("---------------------");

System.out.println("INFO in Term.testToString(): all should be true");

Term t = new Term();

t = string2Term(t1.toString());

System.out.println(t1.toString().equals(t.toString()));

t = new Term();

t = string2Term(t2.toString());

System.out.println(t2.toString().equals(t.toString()));

t = new Term();

t = string2Term(t3.toString());

System.out.println(t3.toString().equals(t.toString()));

t = new Term();

t = string2Term(t4.toString());

System.out.println(t4.toString().equals(t.toString()));

t = new Term();

t = string2Term(t5.toString());

System.out.println(t5.toString().equals(t.toString()));

t = new Term();

t = string2Term(t6.toString());

System.out.println(t6.toString().equals(t.toString()));

t = new Term();

t = string2Term(t7.toString());

System.out.println(t7.toString().equals(t.toString()));

t = new Term();

t = string2Term(t8.toString());

System.out.println(t8.toString().equals(t.toString()));

}

/** ***************************************************************

* Test if the classification function works as expected.

public void testIsVar() {

System.out.println("---------------------");

System.out.println("INFO in testIsVar(): first true, rest false");

System.out.println(t1.isVar());

System.out.println(t2.isVar());

System.out.println(t3.isVar());

System.out.println(t4.isVar());

System.out.println(t5.isVar());

System.out.println(t6.isVar());

}

/** ***************************************************************

* Test if the classification function works as expected.

public void testIsCompound() {

System.out.println("---------------------");

System.out.println("INFO in testIsCompound(): first false, rest true");

System.out.println(t1.isCompound());

System.out.println(t2.isCompound());

System.out.println(t3.isCompound());

System.out.println(t4.isCompound());

System.out.println(t5.isCompound());

System.out.println(t6.isCompound());

}

/** ***************************************************************

* Test if term equality works as expected.

public void testEquality() {

System.out.println("---------------------");

System.out.println("INFO in testEquality(): first ones true, last two false");

System.out.println(t1.equals(t1));

System.out.println(t2.equals(t2));

System.out.println(t3.equals(t3));

System.out.println(t4.equals(t4));

System.out.println(t5.equals(t5));

System.out.println(t6.equals(t6));

System.out.println(t4.equals(t5));

System.out.println(t1.equals(t4));

System.out.println(t3.equals(t4));

}

/** ***************************************************************

* Test if term copying works.

public void testCopy() {

System.out.println("---------------------");

System.out.println("INFO in testCopy(): all true");

Term t = new Term();

t = t1.deepCopy();

System.out.println(t.equals(t1));

t = t2.deepCopy();

System.out.println(t.equals(t2));

t = t3.deepCopy();

System.out.println(t.equals(t3));

t = t4.deepCopy();

System.out.println(t.equals(t4));

t = t5.deepCopy();

System.out.println(t.equals(t5));

t = t6.deepCopy();

System.out.println(t.equals(t6));

}

/** ***************************************************************

* Test if isGround() works as expected.

public void testIsGround() {

System.out.println("---------------------");

System.out.println("INFO in testIsGround(): all true");

System.out.println(!t1.isGround());

System.out.println(t2.isGround());

System.out.println(t3.isGround());

System.out.println(!t4.isGround());

System.out.println(!t5.isGround());

}

/** ***************************************************************

* Test the variable collection.

public void testCollectVars() {

System.out.println("---------------------");

System.out.println("INFO in testCollectVars(): all true");

ArrayList<Term> vars = t1.collectVars();

System.out.println(vars.size()==1);

vars = t2.collectVars();

System.out.println(vars.size()==0);

vars = t3.collectVars();

System.out.println(vars.size()==0);

vars = t4.collectVars();

System.out.println(vars.size()==2);

vars = t5.collectVars();

System.out.println(vars.size()==2);

System.out.println(vars.contains(Term.string2Term("X")));

System.out.println(vars.contains(Term.string2Term("Y")));

}

/** ***************************************************************

* Test the function symbol collection.

public void testCollectFuns() {

System.out.println("---------------------");

System.out.println("INFO in testCollectFuns(): all true");

ArrayList<String> funs = t1.collectFuns();

System.out.println(funs.size() == 0);

funs = t2.collectFuns();

System.out.println(funs.size() == 1 && funs.contains("a"));

funs = t3.collectFuns();

System.out.println(funs.size() == 3 && funs.contains("g") && funs.contains("a") && funs.contains("b"));

funs = t4.collectFuns();

System.out.println(funs.size() == 2 && funs.contains("g") && funs.contains("f"));

funs = t5.collectFuns();

System.out.println(funs.size() == 2 && funs.contains("g") && funs.contains("f"));

funs = t8.collectFuns();

System.out.println(funs.size() == 2 && funs.contains("g") && funs.contains("b"));

}

/** ***************************************************************

* Test signature collection.

public void testCollectSig() {

System.out.println("---------------------");

System.out.println("INFO in testCollectSig(): all should be true");

Signature sig = new Signature();

sig = t1.collectSig(sig);

sig = t2.collectSig(sig);

sig = t3.collectSig(sig);

sig = t4.collectSig(sig);

sig = t5.collectSig(sig);

sig = t6.collectSig(sig);

System.out.println(sig.getArity("f") == 1);

System.out.println(sig.getArity("g") == 2);

System.out.println(sig.getArity("a") == 0);

System.out.println(sig.getArity("b") == 0);

}

/** ***************************************************************

* Test term weight function

public void testTermWeight() {

System.out.println("---------------------");

System.out.println("INFO in testTermWeight()");

System.out.println("Expected: 3 actual: " + t3.weight(1,1));

System.out.println("Expected: 6 actual: " + t3.weight(2,1));

System.out.println("Expected: 1 actual: " + t1.weight(2,1));

}

/** ***************************************************************

* Test subterm function

public void testSubTerm() {

// t6 = "f(X,g(a,b))";

System.out.println("---------------------");

System.out.println("INFO in testSubTerm()");

ArrayList<Integer> al = new ArrayList<Integer>();

System.out.println("Expected: f(X,g(a,b)) actual: " + t6.subterm(al));

al.add(new Integer(0));

System.out.println("Expected: X actual: " + t6.subterm(al));

al = new ArrayList<Integer>();

al.add(new Integer(1));

System.out.println("Expected: g(a,b) actual: " + t6.subterm(al));

al = new ArrayList<Integer>();

al.add(new Integer(1));

al.add(new Integer(0));

System.out.println("Expected: a actual: " + t6.subterm(al));

al = new ArrayList<Integer>();

al.add(new Integer(3));

al.add(new Integer(0));

System.out.println("Expected: null actual: " + t6.subterm(al));

}

/** ***************************************************************

* Test method for this class.

public static void main(String[] args) {

Term p = new Term();

p.setupTests();

p.parseTest();

p.testToString();

p.testIsVar();

p.testIsCompound();

p.testEquality();

p.testCopy();

p.testIsGround();

p.testCollectVars();

p.testCollectFuns();

p.testCollectSig();

p.testTermWeight();

p.testSubTerm();

}

JavaRes/src/atp/Term.java at master · eprover/JavaRes · GitHub

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