/* ======================================================================
The Bodington System Software License, Version 1.0
 
Copyright (c) 2001 The University of Leeds.  All rights reserved.
 
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
 
1.  Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
 
2.  Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
 
3.  The end-user documentation included with the redistribution, if any,
must include the following acknowledgement:  "This product includes
software developed by the University of Leeds
(http://www.bodington.org/)."  Alternately, this acknowledgement may
appear in the software itself, if and wherever such third-party
acknowledgements normally appear.
 
4.  The names "Bodington", "Nathan Bodington", "Bodington System",
"Bodington Open Source Project", and "The University of Leeds" must not be
used to endorse or promote products derived from this software without
prior written permission. For written permission, please contact
d.gardner@leeds.ac.uk.
 
5.  The name "Bodington" may not appear in the name of products derived
from this software without prior written permission of the University of
Leeds.
 
THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO,  TITLE,  THE IMPLIED WARRANTIES
OF QUALITY  AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
EVENT SHALL THE UNIVERSITY OF LEEDS OR ITS CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
=========================================================
 
This software was originally created by the University of Leeds and may contain voluntary
contributions from others.  For more information on the Bodington Open Source Project, please
see http://bodington.org/
 
====================================================================== */

package org.bodington.util;

import java.util.Arrays;

/**
 * Class to allow us to get the column and line number for an index in a string.
 * We only scan the string for newlines if {@link #getColumn(int)} or
 * {@link #getLine(int)} are called. 
 * @author buckett
 */
public class NumberedCharSequence implements CharSequence
{
    private String string;
    private int newlines[];
    
    public NumberedCharSequence(String string)
    {
        this.string = string;
    }

    public int length()
    {
        return string.length();
    }

    public char charAt(int index)
    {
        return string.charAt(index);
    }

    public CharSequence subSequence(int start, int end)
    {
        return string.subSequence(start, end);
    }
    
    /**
     * Gets the line in which the passed index occurs.
     * @param index The index to look for.
     * @return The line number (zero based).
     */
    public int getLine(int index)
    {
        if (newlines == null)
            calculateNewlines();
        
        int newline = Arrays.binarySearch(newlines, index);
        if ( newline < 0)
        {
          return (newline * -1)-1;  
        }
        else
        {
            return newline;
        }
        
    }
    
    /**
     * Gets the column of the current line this index is in.
     * @param index The idnex to look for.
     * @return The column number (zero based).
     */
    public int getColumn(int index)
    {
        int line = getLine(index);
        if (line > 0)
            return index - newlines[line-1] - 1;
        return index;
    }

    private void calculateNewlines()
    {
        IntStack stack = new IntStack();
        int found = 0;
        while ((found = string.indexOf('\n', found)) != -1)
        {
            stack.push(found++);
        }
        newlines = stack.toArray();
    }
    
    /**
     * A tiny stack class which we can push ints into and it should grow
     * automatically. Saves wrapping ints into Integers.
     * @author buckett
     */
    private class IntStack
    {
        int stack[] = new int[10];
        private int last = 0;
        
        /**
         * Push a new element onto the stack.
         * @param value
         */
        public void push(int value)
        {
            if (!(last < stack.length))
                resize();
            stack[last++] = value;
        }
        
        /**
         * Dumps out an array the size of the stack.
         * @return An array.
         */
        public int[] toArray()
        {
            int temp[] = new int[last];
            System.arraycopy(stack, 0, temp, 0, last);
            return temp;
        }

        /**
         * Double the size of the internal array.
         */
        private void resize()
        {
            int temp[] = new int[stack.length*2];
            System.arraycopy(stack,0,temp,0,stack.length);
            stack = temp;
        }
    }

}