/*
 * Leaf.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
 *
 * @see io.devnulllabs.openjava.ptree.ParseTree
 * @see io.devnulllabs.openjava.ptree.ParseTreeObject
 * @version 1.0 last updated: Jun 11, 1997
 * @author  Michiaki Tatsubori
 */
package io.devnulllabs.openjava.ptree;

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

/**
 * The Leaf class is a token-node in the parse tree of OpenJava.
 * Any object of this class or subclasses must be immutable.
 *
 * @see io.devnulllabs.openjava.ptree.ParseTree
 * @see io.devnulllabs.openjava.ptree.NonLeaf
 */
public class Leaf extends ParseTreeObject implements ParseTree {
    protected void replaceChildWith(ParseTree dist, ParseTree replacement)
        throws ParseTreeException {
        throw new ParseTreeException("no child");
    }

    /** textString is the text of this token. */
    private String textString = null;

    /** tokenID is the identifer number of this token */
    private int tokenID = 0;

    /** line is the number of the line at which this token is. */
    public int line = -1;

    /** charBegin is the number of the character at which this token is. */
    public int charBegin = -1;

    /**
     * Allocates a new leaf(token) with its text.
     *
     * @param  term_num  dummy parameter.
     * @param  str  its text.
     */
    public Leaf(String str) {
        this(-1, str, -1, -1);
    }

    /**
     * Allocates a new leaf(token) with its text.
     *
     * @param  term_num  dummy parameter.
     * @param  str  its text.
     */
    public Leaf(int term_num, String str) {
        this(term_num, str, -1, -1);
    }

    /**
     * Allocates a new leaf(token) with its text and where this is.
     *
     * @param  term_num  dummy parameter.
     * @param  str  its text.
     */
    public Leaf(int term_num, String str, int line, int charBegin) {
        tokenID = term_num;
        textString = str;
        this.line = line;
        this.charBegin = charBegin;
    }

    /**
     * Overrides to return its text as the string of this instance.
     *
     * @return  the text of this token.
     */
    public String toString() {
        return textString;
    }

    /**
     * Makes a new copy of this leaf-node.
     * This method equals to makeCopy().
     *
     * @return  the copy of this nonleaf-node as a ptree-node.
     */
    public ParseTree makeRecursiveCopy() {
        return (ParseTree) this.clone();
    }

    /**
     * Makes a new copy of this leaf-node.
     *
     * @return  the copy of this nonleaf-node as a ptree-node.
     */
    public ParseTree makeCopy() {
        return (ParseTree) this.clone();
    }

    /**
     * Tests if the specified ptree-node equals to this leaf-node.
     *
     * @param  p  the ptree-node to be tested.
     * @return  true if p equals to this leaf-node
     */
    public boolean equals(ParseTree p) {
        if (p == null || !(p instanceof Leaf))
            return false;
        if (this == p)
            return true;
        return this.toString().equals(p.toString());
    }

    /**
     * Tests if the specified string equals to this leaf-node's text.
     *
     * @param  p  the ptree-node to be tested.
     * @return  true if p equals to this leaf-node
     */
    public boolean equals(String str) {
        if (str == null)
            return false;
        return this.toString().equals(str);
    }

    /**
     * Returns the identifer-number of this token.
     *
     * @return  the identifer-number of this token.
     */
    public int getTokenID() {
        return tokenID;
    }

    /**
     * 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 void childrenAccept(ParseTreeVisitor visitor) {
        return;
    }

    public void accept(ParseTreeVisitor v) throws ParseTreeException {
        v.visit(this);
    }

}