Java example source code file (TernaryNode.java)

This example Java source code file (TernaryNode.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

expression, immutable, lexicalcontext, nodevisitor, override, stringbuilder, ternarynode

The TernaryNode.java Java example source code

/*
 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package jdk.nashorn.internal.ir;

import jdk.nashorn.internal.ir.annotations.Immutable;
import jdk.nashorn.internal.ir.visitor.NodeVisitor;

/**
 * TernaryNode nodes represent three operand operations (?:).
 */
@Immutable
public final class TernaryNode extends Expression {
    private final Expression test;

    private final Expression trueExpr;

    /** Third argument. */
    private final Expression falseExpr;

    /**
     * Constructor
     *
     * @param token     token
     * @param test      test expression
     * @param trueExpr  expression evaluated when test evaluates to true
     * @param falseExpr expression evaluated when test evaluates to true
     */
    public TernaryNode(final long token, final Expression test, final Expression trueExpr, final Expression falseExpr) {
        super(token, falseExpr.getFinish());
        this.test = test;
        this.trueExpr = trueExpr;
        this.falseExpr = falseExpr;
    }

    private TernaryNode(final TernaryNode ternaryNode, final Expression test, final Expression trueExpr, final Expression falseExpr) {
        super(ternaryNode);
        this.test = test;
        this.trueExpr = trueExpr;
        this.falseExpr = falseExpr;
    }

    @Override
    public Node accept(final NodeVisitor<? extends LexicalContext> visitor) {
        if (visitor.enterTernaryNode(this)) {
            final Expression newTest = (Expression)getTest().accept(visitor);
            final Expression newTrueExpr = (Expression)getTrueExpression().accept(visitor);
            final Expression newFalseExpr = (Expression)falseExpr.accept(visitor);
            return visitor.leaveTernaryNode(setTest(newTest).setTrueExpression(newTrueExpr).setFalseExpression1(newFalseExpr));
        }

        return this;
    }

    @Override
    public void toString(final StringBuilder sb) {
        final boolean testParen  = tokenType().needsParens(getTest().tokenType(), true);
        final boolean trueParen  = tokenType().needsParens(getTrueExpression().tokenType(), false);
        final boolean falseParen = tokenType().needsParens(getFalseExpression().tokenType(), false);

        if (testParen) {
            sb.append('(');
        }
        getTest().toString(sb);
        if (testParen) {
            sb.append(')');
        }

        sb.append(" ? ");

        if (trueParen) {
            sb.append('(');
        }
        getTrueExpression().toString(sb);
        if (trueParen) {
            sb.append(')');
        }

        sb.append(" : ");

        if (falseParen) {
            sb.append('(');
        }
        getFalseExpression().toString(sb);
        if (falseParen) {
            sb.append(')');
        }
    }

    @Override
    public boolean isLocal() {
        return getTest().isLocal()
                && getTrueExpression().isLocal()
                && getFalseExpression().isLocal();
    }

    /**
     * Get the test expression for this ternary expression, i.e. "x" in x ? y : z
     * @return the test expression
     */
    public Expression getTest() {
        return test;
    }

    /**
     * Get the true expression for this ternary expression, i.e. "y" in x ? y : z
     * @return the true expression
     */
    public Expression getTrueExpression() {
        return trueExpr;
    }

    /**
     * Get the false expression for this ternary expression, i.e. "z" in x ? y : z
     * @return the false expression
     */
    public Expression getFalseExpression() {
        return falseExpr;
    }

    /**
     * Set the test expression for this node
     * @param test new test expression
     * @return a node equivalent to this one except for the requested change.
     */
    public TernaryNode setTest(final Expression test) {
        if (this.test == test) {
            return this;
        }
        return new TernaryNode(this, test, trueExpr, falseExpr);
    }

    /**
     * Set the true expression for this node
     * @param trueExpr new true expression
     * @return a node equivalent to this one except for the requested change.
     */
    public TernaryNode setTrueExpression(final Expression trueExpr) {
        if (this.trueExpr == trueExpr) {
            return this;
        }
        return new TernaryNode(this, test, trueExpr, falseExpr);
    }

    /**
     * Set the false expression for this node
     * @param falseExpr new false expression
     * @return a node equivalent to this one except for the requested change.
     */
    public TernaryNode setFalseExpression1(final Expression falseExpr) {
        if (this.falseExpr == falseExpr) {
            return this;
        }
        return new TernaryNode(this, test, trueExpr, falseExpr);
    }
}