nestedexpression.java

一个很好实用的工作流OSWORKFLOW开发例子.有着非常优秀的灵活性.

/*
 * Copyright (c) 2002-2003 by OpenSymphony
 * All rights reserved.
 */
package com.opensymphony.workflow.query;


/**
 * Nested expressions are used when constructing a workflow query.
 * A nested expression consists of:
 * <li>one or more expressions: Each of them can again be a NestedExpression.
 * <li>operator: The operator used to evaluate the value of the nested expression
 *     from the specified sub expressions.
 *
 * @author Christine Zimmermann
 */
public class NestedExpression extends Expression {
    //~ Static fields/initializers /////////////////////////////////////////////

    /**
    * Constant to specify that all the expressions specified must evaluate to true for
    * an item to be included in the search results.
    */
    public final static int AND = 6;

    /**
     * Constant to specify that at least one of the expressions specified must evaluate to true
     * for an item to be included in the search results.
     */
    public final static int OR = 7;

    //~ Instance fields ////////////////////////////////////////////////////////

    private Expression[] expressions = null;
    private int expressionOperator = AND;

    //~ Constructors ///////////////////////////////////////////////////////////

    public NestedExpression() {
    }

    /**
    * Create a NestedExpression that consists of multiple expressions.
    * @param expressions an array of expressions for this query.
    * @param operator {@link NestedExpression#AND} or {@link NestedExpression#OR}.
    */
    public NestedExpression(Expression[] expressions, int operator) {
        this.expressions = expressions;
        this.expressionOperator = operator;
    }

    //~ Methods ////////////////////////////////////////////////////////////////

    public Expression getExpression(int index) {
        return expressions[index];
    }

    /**
     * Get the number of expressions in this query.
     */
    public int getExpressionCount() {
        return expressions.length;
    }

    public void setExpressionOperator(int expressionOperator) {
        this.expressionOperator = expressionOperator;
    }

    /**
     * @return {@link NestedExpression#AND} if all the expressions must match,
     * or {@link NestedExpression#OR} if only one must match.
     */
    public int getExpressionOperator() {
        return this.expressionOperator;
    }

    public void setExpressions(Expression[] expressions) {
        this.expressions = expressions;
    }

    public boolean isNested() {
        return true;
    }
}