path: root/src/main/java/io/devnulllabs/openjava/ptree/ParseTreeObject.java

/*
 * ParseTreeObject.java 1.0
 *
 * This subclass of symbol represents (at least) terminal symbols returned
 * by the scanner and placed on the parse stack.  At present, this
 * class does nothing more than its super class.
 *
 * Jun 11, 1997
 * Sep 5, 1997
 *
 * @see java_cup.runtime.symbol
 * @version 1.0 last updated: Sep 5, 1997
 * @author  Michiaki Tatsubori
 */
package io.devnulllabs.openjava.ptree;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.StringTokenizer;

import io.devnulllabs.openjava.ptree.util.ParseTreeVisitor;
import io.devnulllabs.openjava.ptree.util.SourceCodeWriter;

/**
 * The ParseTree class presents for the node of parse tree.
 * This may be a token node, Leaf, or may be a nonterminal node, NonLeaf.
 *
 * @see io.devnulllabs.openjava.ptree.Leaf
 * @see io.devnulllabs.openjava.ptree.NonLeaf
 */
public abstract class ParseTreeObject
    extends Object
    implements ParseTree, Cloneable {
    /**
     * Why this modifier is not final ?
     * - Because of javac bug in excuting it with -O option.
     */
    protected static String LN;
    static {
        StringWriter strw = new StringWriter();
        PrintWriter pw = new PrintWriter(strw);
        pw.println();
        pw.close();
        LN = strw.toString();
    }

    private ParseTreeObject parent;
    /*************/
    public /*private*/
    final ParseTreeObject getParent() {
        return parent;
    }
    protected final void setParent(ParseTreeObject parent) {
        this.parent = parent;
    }
    public final void replace(ParseTree replacement)
        throws ParseTreeException {
        ParseTreeObject p = getParent();
        if (p == null)
            throw new ParseTreeException("no parent");
        p.replaceChildWith(this, replacement);
    }
    protected abstract void replaceChildWith(
        ParseTree dist,
        ParseTree replacement)
        throws ParseTreeException;

    /**
     * Arrocates new parse-tree object and set identifier number
     * on the object.
     *
     */
    public ParseTreeObject() {
        setObjectID();
    }

    /**
     * clone() is fixed as a shallow copy.
     *
     * @return  the copy of this ptree-node.
     */
    protected final Object clone() {
        try {
            ParseTreeObject result = (ParseTreeObject) super.clone();
            result.setObjectID();
            return result;
        } catch (CloneNotSupportedException e) {
            return null;
        }
    }

    /**
     * shallow copy
     */
    public ParseTree makeCopy() {
        return (ParseTree) clone();
    }

    /**
     * deep copy
     */
    public abstract ParseTree makeRecursiveCopy();

    /**
     * Tests if this parse-tree-node's value equals to the specified
     * ptree-node's.
     *
     * @return  true if two values are same.
     */
    public abstract boolean equals(ParseTree p);

    public int hashCode() {
        return getObjectID();
    }

    /**
     * Generates a string object of regular Java source code
     * representing this parse-tree.
     *
     * @return string which represents this parse-tree
     */
    public String toString() {
        StringWriter strwriter = new StringWriter();
        PrintWriter out = new PrintWriter(strwriter);
        SourceCodeWriter writer = new SourceCodeWriter(out);
        try {
            this.accept(writer);
        } catch (ParseTreeException e) {
            System.err.println("fail in toString()");
        }
        out.close();
        return strwriter.toString();
    }

    /**
     * May return true if two ptree-nodes don't refer to not the
     * same objects but their contents are equivalent.
     *
     * @param p the node
     * @param q the node to compare
     * @return true if p equals c
     */
    public static final boolean equal(ParseTree p, ParseTree q) {
        if (p == null && q == null)
            return true;
        if (p == null || q == null)
            return false;
        if (p == q)
            return true;
        return p.equals(q);
    }

    /**
     * The object ID is object identifier number in order to determine
     * two ptree variables refer to the same object.
     */
    private int objectID = -1;

    /** The idCount counts up generated ptree objects */
    private static int idCount = 0;

    public static final int lastObjectID() {
        return idCount;
    }

    /**
     * Increments idCount class variable and set the instance's
     * object identifier number to the number of idCount variable.
     *
     */
    private synchronized final void setObjectID() {
        idCount++;
        objectID = idCount;
    }

    /**
     * Returns
     *
     * @param id ID
     * @return Name the ID represents
     */
    public final int getObjectID() {
        return objectID;
    }

    /**
     * Generates the string expression from this node.  Returned
     * string doesn't have '"' without cancel ( \" ) and doesn't have
     * newline.<p>
     *
     * This method is useful to embed ptree objects as a string literal
     * in source code.
     *
     * @return the flatten string which this node represents
     */
    public String toFlattenString() {
        StringBuffer ret = null;

        /* cancel double quotes and back slashs */
        java.util.StringTokenizer canceller =
            new StringTokenizer(this.toString(), "\\\"", true);
        ret = new StringBuffer();

        while (canceller.hasMoreTokens()) {
            String buf = canceller.nextToken();
            if (buf.equals("\\") || buf.equals("\"")) {
                ret.append("\\");
            }
            ret.append(buf);
        }

        /* remove new line chars */
        java.util.StringTokenizer lnremover =
            new StringTokenizer(ret.toString(), "\n\r", false);
        ret = new StringBuffer();

        while (lnremover.hasMoreTokens()) {
            ret.append(" " + lnremover.nextToken());
        }

        return ret.toString();
    }

    /**
     * Accepts a <code>ParseTreeVisitor</code> object as the role of a
     * Visitor in the Visitor pattern, as the role of an Element in
     * the Visitor pattern.<p>
     *
     * This invoke an appropriate <code>visit()</code> method on the
     * accepted visitor.
     *
     * @param visitor a visitor
     */
    public abstract void accept(ParseTreeVisitor visitor)
        throws ParseTreeException;

    /*
    public void accept( ParseTreeVisitor visitor ) throws ParseTreeException {
    Class active_type = this.getClass();
    Class visitor_clazz = visitor.getClass();
    try {
        Method visit_method
        = visitor_clazz.getMethod( "visit",
                       new Class[]{ active_type } );
        visit_method.invoke( visitor, new Object[]{ this } );
    } catch ( Exception e ) {
        System.err.println( e.toString() );
        System.err.println( "\telement\t-" + active_type.toString() );
        System.err.println( "\tvisitor\t-" + visitor_clazz.toString() );
    }
    }
    */

    /**
     * Accepts a <code>ParseTreeVisitor</code> object as the role of a
     * Visitor in the Visitor pattern, as the role of an Element in the
     * Visitor pattern.<p>
     *
     * This invoke an appropriate <code>visit()</code> method on each
     * child <code>ParseTree</code> object with this visitor.
     *
     * @param visitor a visitor
     **/
    public abstract void childrenAccept(ParseTreeVisitor visitor)
        throws ParseTreeException;

}