LexicalContextNode.java

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package jdk.nashorn.internal.ir;

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


/**
 * Interface for nodes that can be part of the lexical context.
 * @see LexicalContext
 */
public interface LexicalContextNode {
    /**
     * Accept function for the node given a lexical context. It must be prepared
     * to replace itself if present in the lexical context
     *
     * @param lc      lexical context
     * @param visitor node visitor
     *
     * @return new node or same node depending on state change
     */
    Node accept(final LexicalContext lc, final NodeVisitor<? extends LexicalContext> visitor);

    // Would be a default method on Java 8
    /**
     * Helper class for accept for items of this lexical context, delegates to the
     * subclass accept and makes sure that the node is on the context before accepting
     * and gets popped after accepting (and that the stack is consistent in that the
     * node has been replaced with the possible new node resulting in visitation)
     */
    static class Acceptor {
        static Node accept(final LexicalContextNode node, final NodeVisitor<? extends LexicalContext> visitor) {
            final LexicalContext lc = visitor.getLexicalContext();
            lc.push(node);
            final Node newNode = node.accept(lc, visitor);
            return lc.pop(newNode);
        }
    }
}