001/*
002 * Copyright (c) 2006-2011 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * All rights reserved. This program and the accompanying materials
005 * are made available under the terms of the Eclipse Public License v1.0
006 * which accompanies this distribution, and is available at
007 * http://www.eclipse.org/legal/epl-v10.html
008 *
009 * Contributors:
010 *     Nuxeo - initial API and implementation
011 *
012 * $Id$
013 */
014
015package org.nuxeo.ecm.core.query.sql.model;
016
017import org.nuxeo.ecm.core.query.sql.NXQL;
018
019/**
020 * An infix expression.
021 *
022 * @author <a href="mailto:bs@nuxeo.com">Bogdan Stefanescu</a>
023 */
024public class Expression implements Operand {
025
026    private static final long serialVersionUID = 6007989243273673300L;
027
028    public final Operator operator;
029
030    public final Operand lvalue;
031
032    public final Operand rvalue;
033
034    public Expression(Operand lvalue, Operator operator, Operand rvalue) {
035        this.lvalue = lvalue;
036        this.rvalue = rvalue;
037        this.operator = operator;
038    }
039
040    @Override
041    public void accept(IVisitor visitor) {
042        visitor.visitExpression(this);
043    }
044
045    /**
046     * Is the unary operator pretty-printed after the operand?
047     */
048    public boolean isSuffix() {
049        return operator == Operator.ISNULL || operator == Operator.ISNOTNULL;
050    }
051
052    @Override
053    public String toString() {
054        if (rvalue == null) {
055            if (isSuffix()) {
056                return lvalue.toString() + ' ' + operator.toString();
057            } else {
058                return operator.toString() + ' ' + lvalue.toString();
059            }
060        } else {
061            return lvalue.toString() + ' ' + operator.toString() + ' ' + rvalue.toString();
062        }
063    }
064
065    @Override
066    public boolean equals(Object obj) {
067        if (obj == this) {
068            return true;
069        }
070        if (obj instanceof Expression) {
071            Expression e = (Expression) obj;
072            if (operator.id != e.operator.id) {
073                return false;
074            }
075            if (!lvalue.equals(e.lvalue)) {
076                return false;
077            }
078            if (rvalue != null) {
079                if (!rvalue.equals(e.rvalue)) {
080                    return false;
081                }
082            } else if (e.rvalue != null) {
083                return false;
084            }
085            return true;
086        }
087        return false;
088    }
089
090    @Override
091    public int hashCode() {
092        int result = 17;
093        result = 37 * result + operator.hashCode();
094        result = 37 * result + lvalue.hashCode();
095        result = 37 * result + (rvalue == null ? 0 : rvalue.hashCode());
096        return result;
097    }
098
099    public boolean isPathExpression() {
100        return (lvalue instanceof Reference) && NXQL.ECM_PATH.equals(((Reference) lvalue).name);
101    }
102
103}