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Rhino is an open-source implementation of JavaScript written entirely in Java. It is typically embedded into Java applications to provide scripting to end users.
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/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.javascript.ast;

import org.mozilla.javascript.Token;

/**
 * AST node representing an expression in a statement context. The node type is {@link
 * Token#EXPR_VOID} if inside a function, or else {@link Token#EXPR_RESULT} if inside a script.
 */
public class ExpressionStatement extends AstNode {

    private AstNode expr;

    {
        type = Token.EXPR_VOID;
    }

    /**
     * Called by the parser to set node type to EXPR_RESULT if this node is not within a Function.
     */
    public void setHasResult() {
        type = Token.EXPR_RESULT;
    }

    public ExpressionStatement() {}

    /**
     * Constructs a new {@code ExpressionStatement} wrapping the specified expression. Sets this
     * node's position to the position of the wrapped node, and sets the wrapped node's position to
     * zero. Sets this node's length to the length of the wrapped node.
     *
     * @param expr the wrapped expression
     * @param hasResult {@code true} if this expression has side effects. If true, sets node type to
     *     EXPR_RESULT, else to EXPR_VOID.
     */
    public ExpressionStatement(AstNode expr, boolean hasResult) {
        this(expr);
        if (hasResult) setHasResult();
    }

    /**
     * Constructs a new {@code ExpressionStatement} wrapping the specified expression. Sets this
     * node's position to the position of the wrapped node, and sets the wrapped node's position to
     * zero. Sets this node's length to the length of the wrapped node.
     *
     * @param expr the wrapped expression
     */
    public ExpressionStatement(AstNode expr) {
        this(expr.getPosition(), expr.getLength(), expr);
    }

    public ExpressionStatement(int pos, int len) {
        super(pos, len);
    }

    /**
     * Constructs a new {@code ExpressionStatement}
     *
     * @param expr the wrapped {@link AstNode}. The {@code ExpressionStatement}'s bounds are set to
     *     those of expr, and expr's parent is set to this node.
     * @throws IllegalArgumentException if {@code expr} is null
     */
    public ExpressionStatement(int pos, int len, AstNode expr) {
        super(pos, len);
        setExpression(expr);
    }

    /** Returns the wrapped expression */
    public AstNode getExpression() {
        return expr;
    }

    /**
     * Sets the wrapped expression, and sets its parent to this node.
     *
     * @throws IllegalArgumentException} if expression is {@code null}
     */
    public void setExpression(AstNode expression) {
        assertNotNull(expression);
        expr = expression;
        expression.setParent(this);
        setLineno(expression.getLineno());
    }

    /**
     * Returns true if this node has side effects
     *
     * @throws IllegalStateException if expression has not yet been set.
     */
    @Override
    public boolean hasSideEffects() {
        return type == Token.EXPR_RESULT || expr.hasSideEffects();
    }

    @Override
    public String toSource(int depth) {
        StringBuilder sb = new StringBuilder();
        sb.append(expr.toSource(depth));
        sb.append(";");
        if (this.getInlineComment() != null) {
            sb.append(this.getInlineComment().toSource(depth));
        }
        sb.append("\n");
        return sb.toString();
    }

    /** Visits this node, then the wrapped statement. */
    @Override
    public void visit(NodeVisitor v) {
        if (v.visit(this)) {
            expr.visit(v);
        }
    }
}