/*
 * Copyright (c) 2006, Regents of the University of California
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in
 *   the documentation and/or other materials provided with the
 *   distribution.  
 *
 * * Neither the name of the University of California, Berkeley nor
 *   the names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior 
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package blog;

import java.util.*;

public class SymbolTerm extends Term {
    

    public SymbolTerm(String symbol) {
	name = symbol;
    }
    
    

    public boolean isLogicalVar() {
	checkCompiled();
	return (var != null);
    }

    

    public LogicalVar getLogicalVar() {
	checkCompiled();
	return var;
    }

    

    public Function getFunc() {
	checkCompiled();
	return func;
    }

    public boolean checkTypesAndScope(Model model, Map scope) {
	if ((var == null) && (func == null)) {
	    var = (LogicalVar) scope.get(name);
	    if (var == null) {
		func = model.getFunction(new Function.Sig(name));
		if (func == null) {
		    System.err.println
			(getLocation() + ": Symbol \"" + name 
			 + "\" is neither a variable in the current scope "
			 + "nor a zero-ary function.");
		    return false;
		}
	    }
	} else if (var != null) {
	    if (var != scope.get(name)) {
		System.err.println
		    (getLocation() + ": LogicalVar " + var 
		     + " is not in scope.");
		return false;
	    }
	}

	return true;
    }

    public Term getTermInScope(Model model, Map scope) {
	Term result = null;
	if (checkTypesAndScope(model, scope)) {
	    if (func != null) {
		result = new FuncAppTerm(func);
	    } else {
		result = var;
	    }
	    result.setLocation(getLocation());
	}
	return result;
    }

    public int compile(LinkedHashSet callStack) {
	if (func != null) {
	    callStack.add(this);
	    int errors = func.compile(callStack);
	    callStack.remove(this);
	    return errors;
	}
	return 0; // no compilation necessary for logical variables
    }

    public Type getType() {
	checkCompiled();
	return ((var != null) ? var.getType() : func.getRetType());
    }

    public Object evaluate(EvalContext context) {
	if (var != null) {
	    return context.getLogicalVarValue(var);
	}
	return func.getValueInContext(NO_ARGS, context, true);
    }

    

    public BayesNetVar getVariable() {
	if (func instanceof RandomFunction) {
	    return new RandFuncAppVar((RandomFunction) func, NO_ARGS, true);
	}
	return new DerivedVar(this);
    }

    public boolean containsRandomSymbol() {
	checkCompiled();
	return (func instanceof RandomFunction);
    }

    public Set getFreeVars() {
	checkCompiled();
	return ((var != null) ? 
		Collections.singleton(var) : Collections.EMPTY_SET);
    }

    public ArgSpec getSubstResult(Substitution subst, 
				  Set<LogicalVar> boundVars) {
	throw new UnsupportedOperationException
	    ("Can't apply substitution to SymbolTerm.  Make sure "
	     + "checkTypesAndScope is called to eliminate SymbolTerms "
	     + "before a substitutions is applied.");
    }

    public boolean isConstantNull() {
	checkCompiled();
	return (func == BuiltInFunctions.NULL);
    }

    public boolean makeOverlapSubst(Term t, Substitution theta){
	// this shouldn't ever get called...
	return false;
    }

    public Term getCanonicalVersion() {
	throw new UnsupportedOperationException
	    ("Can't get canonical version of SymbolTerm.  Make sure "
	     + "checkTypesAndScope is called to eliminate SymbolTerms "
	     + "before getCanonicalVersion is called.");
    }

    public boolean equals(Object o) {
	checkCompiled();
	if (o instanceof SymbolTerm) {
	    SymbolTerm other = (SymbolTerm) o;
	    if (var != null) {
		return (var == other.getLogicalVar());
	    }
	    return (func.equals(other.getFunc()));
	}
	return false;
    }

    public int hashCode() {
	checkCompiled();
	return ((var != null) ? var.hashCode() : func.hashCode());
    }

    public String toString() {
	return name;
    }

    private void checkCompiled() {
	if ((func == null) && (var == null)) {
	    throw new IllegalStateException
		("SymbolTerm \"" + this + "\" has not been succesfully "
		 + "compiled.");
	}
    }

    private String name;
    private Function func;
    private LogicalVar var;

    private static Object[] NO_ARGS = new Object[0];
}

This file was generated on Tue Jun 08 17:53:36 PDT 2010 from file SymbolTerm.java
by the ilog.language.tools.Hilite Java tool written by Hassan Aït-Kaci