Patch.java

package org.webcat.diff;

import java.util.LinkedList;

//--------------------------------------------------------------------------
/**
 * Class representing one patch Diff.Operation.
 *
 * @param <T> the type of object in the list
 */
public class Patch<T>
{
    public DiffList<T> diffs;
    public int start1;
    public int start2;
    public int length1;
    public int length2;


    // ----------------------------------------------------------
    /**
     * Constructor. Initializes with an empty list of diffs.
     */
    public Patch()
    {
        this.diffs = new DiffList<T>();
    }


    // ----------------------------------------------------------
    /**
     * Emmulate GNU diff's format. Header: @@ -382,8 +481,9 @@ Indicies are
     * printed as 1-based, not 0-based.
     *
     * @return The GNU diff List<T>.
     */
    public String toString()
    {
        String coords1, coords2;

        if (this.length1 == 0)
        {
            coords1 = this.start1 + ",0";
        }
        else if (this.length1 == 1)
        {
            coords1 = Integer.toString(this.start1 + 1);
        }
        else
        {
            coords1 = (this.start1 + 1) + "," + this.length1;
        }

        if (this.length2 == 0)
        {
            coords2 = this.start2 + ",0";
        }
        else if (this.length2 == 1)
        {
            coords2 = Integer.toString(this.start2 + 1);
        }
        else
        {
            coords2 = (this.start2 + 1) + "," + this.length2;
        }

        StringBuilder text = new StringBuilder();
        text.append("@@ -").append(coords1).append(" +").append(coords2)
                .append(" @@\n");

        // Escape the body of the patch with %xx notation.
        for (Diff<T> aDiff : this.diffs)
        {
            switch (aDiff.operation)
            {
            case INSERT:
                text.append('+');
                break;
            case DELETE:
                text.append('-');
                break;
            case EQUAL:
                text.append(' ');
                break;
            }

            text.append(aDiff.list).append("\n");
        }

        return text.toString();
    }
}