xahaud/modules/beast_core/text/TextDiff.h

//------------------------------------------------------------------------------
/*
    This file is part of Beast: https://github.com/vinniefalco/Beast
    Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>

    Portions of this file are from JUCE.
    Copyright (c) 2013 - Raw Material Software Ltd.
    Please visit http://www.juce.com

    Permission to use, copy, modify, and/or distribute this software for any
    purpose  with  or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.

    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================

#ifndef BEAST_TEXTDIFF_H_INCLUDED
#define BEAST_TEXTDIFF_H_INCLUDED


/**
    Calculates and applies a sequence of changes to convert one text string into
    another.

    Once created, the TextDiff object contains an array of change objects, where
    each change can be either an insertion or a deletion. When applied in order
    to the original string, these changes will convert it to the target string.
*/
class BEAST_API TextDiff
{
public:
    /** Creates a set of diffs for converting the original string into the target. */
    TextDiff (const String& original,
              const String& target);

    /** Applies this sequence of changes to the original string, producing the
        target string that was specified when generating them.

        Obviously it only makes sense to call this function with the string that
        was originally passed to the constructor. Any other input will produce an
        undefined result.
    */
    String appliedTo (String text) const;

    /** Describes a change, which can be either an insertion or deletion. */
    struct Change
    {
        String insertedText; /**< If this change is a deletion, this string will be empty; otherwise,
                                  it'll be the text that should be inserted at the index specified by start. */
        int start;    /**< Specifies the character index in a string at which text should be inserted or deleted. */
        int length;   /**< If this change is a deletion, this specifies the number of characters to delete. For an
                           insertion, this is the length of the new text being inserted. */

        /** Returns true if this change is a deletion, or false for an insertion. */
        bool isDeletion() const noexcept;

        /** Returns the result of applying this change to a string. */
        String appliedTo (const String& original) const noexcept;
    };

    /** The list of changes required to perform the transformation.
        Applying each of these, in order, to the original string will produce the target.
    */
    Array<Change> changes;
};


#endif   // BEAST_TEXTDIFF_H_INCLUDED