Redmine

  def visual_source_safe_field_tags(form, repository)

      content_tag('p', form.text_field(:url, :size => 60, :required => true, :disabled => (repository && !repository.root_url.blank?)) +

                       '<br />(*/srcsafe.ini)') +

      content_tag('p', form.text_field(:login, :size => 30)) +

      content_tag('p', form.password_field(:password, :size => 30))

      #content_tag('p', select_tag('vss_lang', "<option>en</option><option>ja</option>"))

  end

# redMine - project management software

# Copyright (C) 2006-2007  Jean-Philippe Lang

#

# This program is free software; you can redistribute it and/or

# modify it under the terms of the GNU General Public License

# as published by the Free Software Foundation; either version 2

# of the License, or (at your option) any later version.

# 

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

# 

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

require 'redmine/scm/adapters/visual_source_safe_adapter'

require 'redmine/scm/adapters/abstract_adapter'

class Repository::VisualSourceSafe < Repository

  attr_protected :root_url

  validates_presence_of :url

  validates_format_of :url, :with => /^.*srcsafe\.ini/i

  def scm_adapter

    Redmine::Scm::Adapters::VisualSourceSafeAdapter

  end

  def self.scm_name

    'VisualSourceSafe'

  end

  def fetch_changesets

	#use like CVS

	STDERR.puts "fetch_changeset start!"

    #not the preferred way with CVS. maybe we should introduce always a cron-job for this

    last_commit = changesets.maximum(:committed_on)

    # some nifty bits to introduce a commit-id with cvs

    # natively cvs doesn't provide any kind of changesets, there is only a revision per file.

    # we now take a guess using the author, the commitlog and the commit-date.

    # last one is the next step to take. the commit-date is not equal for all 

    # commits in one changeset. cvs update the commit-date when the *,v file was touched. so

    # we use a small delta here, to merge all changes belonging to _one_ changeset

    #time_delta=10.seconds

    time_delta=10.seconds

    fetch_since = latest_changeset ? latest_changeset.committed_on : nil

    revisions = nil

    transaction do

      revisions = scm.revisions('', fetch_since, nil, :with_paths => true)

      STDERR.puts "fetch_changeset revisions.size = #{revisions.size}"

      STDERR.puts "changesets.size = #{changesets.size}"

      tmp_rev_num = changesets.size + 1

      revisions.each do |revision|

        # only add the change to the database, if it doen't exists. the cvs log

        # is not exclusive at all. 

        cs1 = changes.find_by_path_and_revision(scm.with_leading_slash(revision.paths[0][:path]), revision.paths[0][:revision])

        unless cs1

          revision

          cs=Changeset.find(:first, :conditions=>{

            :committed_on=>revision.time-time_delta..revision.time+time_delta,

            :committer=>revision.author,

            :comments=>revision.message

          })

          # create a new changeset.... 

          unless cs 

            # we use a temporaray revision number here (just for inserting)

            # later on, we calculate a continous positive number

            latest = changesets.find(:first, :order => 'id DESC')

            cs = Changeset.create(:repository => self,

                                  :revision => "_#{tmp_rev_num}", 

                                  :committer => revision.author, 

                                  :committed_on => revision.time,

                                  :comments => revision.message)

            tmp_rev_num += 1

            STDERR.puts "Create ChangeSet"

          end

          #convert CVS-File-States to internal Action-abbrevations

          #default action is (M)odified

          action="M"

          act = revision.paths[0][:action]

          #need check only 'Added' or 'Created' or 'Deleted'

		  if /^Added/ =~ act or /^Created/ =~ act or /^Recovered/ =~ act or /^Shared/ =~ act

		    action="A"

		  elsif /^Deleted/ =~ act

		    action="D"

		  end

         Change.create(:changeset => cs,

          :action => action,

          :path => scm.with_leading_slash(revision.paths[0][:path]),

          :revision => revision.paths[0][:revision],

          :branch => revision.paths[0][:branch]

          )

        end

      end

      c = changesets.find(:first, :order => 'committed_on DESC, id DESC', :conditions => "revision NOT LIKE '_%'")

      next_rev = c.nil? ? 1 : (c.revision.to_i + 1)

      changesets.find(:all, :order => 'committed_on ASC, id ASC', :conditions => "revision LIKE '_%'").each do |changeset|

        changeset.update_attribute :revision, next_rev

        next_rev += 1

      end

    end

	STDERR.puts "fetch_changeset end!"

  end

  def diff(path, rev, rev_to, type2)

    #convert rev to revision. CVS can't handle changesets here

    diffx = Redmine::Scm::Adapters::DiffTableList.new([], type2)

    changeset_from=changesets.find_by_revision(rev)

    if rev_to.to_i > 0 

      changeset_to=changesets.find_by_revision(rev_to)

    end

    changeset_from.changes.each() do |change_from|

      revision_from=nil

      revision_to=nil      

      revision_from=change_from.revision if path.nil? || (change_from.path.starts_with? scm.with_leading_slash(path))

      if revision_from

        if changeset_to

          changeset_to.changes.each() do |change_to|

            revision_to=change_to.revision if change_to.path==change_from.path 

          end

        end

        unless revision_to

          revision_to=scm.get_previous_revision(change_from.path, revision_from)

        end

        diff2 = scm.diff(change_from.path, revision_from, revision_to, type2)

        diffx=diff2 if diff2

      end

    end

    return diffx

  end

end

REDMINE_SUPPORTED_SCM = %w( Subversion Darcs Mercurial Cvs Bazaar Git VisualSourceSafe)

# redMine - project management software

# Copyright (C) 2006-2007  Jean-Philippe Lang

# Visual Source Safe modules: Aruo Miura

#

# This program is free software; you can redistribute it and/or

# modify it under the terms of the GNU General Public License

# as published by the Free Software Foundation; either version 2

# of the License, or (at your option) any later version.

# 

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

# 

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

require 'redmine/scm/adapters/abstract_adapter'

require 'rexml/document'

require 'win32ole'

require 'tempfile'

#require	'nkf'

#============copy of diff-lcs, only change names. Diff -> DiffX

#lcs.rb

module DiffX

    # = Diff::LCS 1.1.2

    # Computes "intelligent" differences between two sequenced Enumerables.

    # This is an implementation of the McIlroy-Hunt "diff" algorithm for

    # Enumerable objects that include Diffable.

    #

    # Based on Mario I. Wolczko's <mario@wolczko.com> Smalltalk version

    # (1.2, 1993) and Ned Konz's <perl@bike-nomad.com> Perl version

    # (Algorithm::Diff).

    #

    # == Synopsis

    #   require 'diff/lcs'

    #

    #   seq1 = %w(a b c e h j l m n p)

    #   seq2 = %w(b c d e f j k l m r s t)

    #

    #   lcs = Diff::LCS.LCS(seq1, seq2)

    #   diffs = Diff::LCS.diff(seq1, seq2)

    #   sdiff = Diff::LCS.sdiff(seq1, seq2)

    #   seq = Diff::LCS.traverse_sequences(seq1, seq2, callback_obj)

    #   bal = Diff::LCS.traverse_balanced(seq1, seq2, callback_obj)

    #   seq2 == Diff::LCS.patch(seq1, diffs)

    #   seq2 == Diff::LCS.patch!(seq1, diffs)

    #   seq1 == Diff::LCS.unpatch(seq2, diffs)

    #   seq1 == Diff::LCS.unpatch!(seq2, diffs)

    #   seq2 == Diff::LCS.patch(seq1, sdiff)

    #   seq2 == Diff::LCS.patch!(seq1, sdiff)

    #   seq1 == Diff::LCS.unpatch(seq2, sdiff)

    #   seq1 == Diff::LCS.unpatch!(seq2, sdiff)

    #

    # Alternatively, objects can be extended with Diff::LCS:

    #

    #   seq1.extend(Diff::LCS)

    #   lcs = seq1.lcs(seq2)

    #   diffs = seq1.diff(seq2)

    #   sdiff = seq1.sdiff(seq2)

    #   seq = seq1.traverse_sequences(seq2, callback_obj)

    #   bal = seq1.traverse_balanced(seq2, callback_obj)

    #   seq2 == seq1.patch(diffs)

    #   seq2 == seq1.patch!(diffs)

    #   seq1 == seq2.unpatch(diffs)

    #   seq1 == seq2.unpatch!(diffs)

    #   seq2 == seq1.patch(sdiff)

    #   seq2 == seq1.patch!(sdiff)

    #   seq1 == seq2.unpatch(sdiff)

    #   seq1 == seq2.unpatch!(sdiff)

    # 

    # Default extensions are provided for Array and String objects through

    # the use of 'diff/lcs/array' and 'diff/lcs/string'.

    #

    # == Introduction (by Mark-Jason Dominus)

    # 

    # <em>The following text is from the Perl documentation. The only

    # changes have been to make the text appear better in Rdoc</em>.

    #

    # I once read an article written by the authors of +diff+; they said

    # that they hard worked very hard on the algorithm until they found the

    # right one.

    #

    # I think what they ended up using (and I hope someone will correct me,

    # because I am not very confident about this) was the `longest common

    # subsequence' method. In the LCS problem, you have two sequences of

    # items:

    #

    #    a b c d f g h j q z

    #    a b c d e f g i j k r x y z

    #

    # and you want to find the longest sequence of items that is present in

    # both original sequences in the same order. That is, you want to find a

    # new sequence *S* which can be obtained from the first sequence by

    # deleting some items, and from the second sequence by deleting other

    # items. You also want *S* to be as long as possible. In this case *S*

    # is:

    # 

    #    a b c d f g j z

    #

    # From there it's only a small step to get diff-like output:

    #

    #    e   h i   k   q r x y

    #    +   - +   +   - + + +

    #

    # This module solves the LCS problem. It also includes a canned function

    # to generate +diff+-like output.

    #

    # It might seem from the example above that the LCS of two sequences is

    # always pretty obvious, but that's not always the case, especially when

    # the two sequences have many repeated elements. For example, consider

    #

    #    a x b y c z p d q

    #    a b c a x b y c z

    #

    # A naive approach might start by matching up the +a+ and +b+ that

    # appear at the beginning of each sequence, like this:

    # 

    #    a x b y c         z p d q

    #    a   b   c a b y c z

    #

    # This finds the common subsequence +a b c z+. But actually, the LCS is

    # +a x b y c z+:

    #

    #          a x b y c z p d q

    #    a b c a x b y c z

    #

    # == Author

    # This version is by Austin Ziegler <diff-lcs@halostatue.ca>.

    #

    # It is based on the Perl Algorithm::Diff by Ned Konz

    # <perl@bike-nomad.com>, copyright &copy; 2000 - 2002 and the Smalltalk

    # diff version by Mario I. Wolczko <mario@wolczko.com>, copyright &copy;

    # 1993. Documentation includes work by Mark-Jason Dominus.

    #

    # == Licence

    # Copyright © 2004 Austin Ziegler

    # This program is free software; you can redistribute it and/or modify it

    # under the same terms as Ruby, or alternatively under the Perl Artistic

    # licence.

    #

    # == Credits

    # Much of the documentation is taken directly from the Perl

    # Algorithm::Diff implementation and was written originally by Mark-Jason

    # Dominus <mjd-perl-diff@plover.com> and later by Ned Konz. The basic Ruby

    # implementation was re-ported from the Smalltalk implementation, available

    # at ftp://st.cs.uiuc.edu/pub/Smalltalk/MANCHESTER/manchester/4.0/diff.st

    #

    # #sdiff and #traverse_balanced were written for the Perl version by Mike

    # Schilli <m@perlmeister.com>.

    #

    # "The algorithm is described in <em>A Fast Algorithm for Computing Longest

    # Common Subsequences</em>, CACM, vol.20, no.5, pp.350-353, May 1977, with

    # a few minor improvements to improve the speed."

  module LCS

    VERSION = '1.1.2'

  end

end

module DiffX::LCS

    # Returns an Array containing the longest common subsequence(s) between

    # +self+ and +other+. See Diff::LCS#LCS.

    #

    #   lcs = seq1.lcs(seq2)

  def lcs(other, &block) #:yields self[ii] if there are matched subsequences:

    DiffX::LCS.LCS(self, other, &block)

  end

    # Returns the difference set between +self+ and +other+. See

    # Diff::LCS#diff.

  def diff(other, callbacks = nil, &block)

    DiffX::LCS::diff(self, other, callbacks, &block)

  end

    # Returns the balanced ("side-by-side") difference set between +self+ and

    # +other+. See Diff::LCS#sdiff.

  def sdiff(other, callbacks = nil, &block)

    DiffX::LCS::sdiff(self, other, callbacks, &block)

  end

    # Traverses the discovered longest common subsequences between +self+ and

    # +other+. See Diff::LCS#traverse_sequences.

  def traverse_sequences(other, callbacks = nil, &block)

    traverse_sequences(self, other, callbacks || DiffX::LCS::YieldingCallbacks,

                       &block)

  end

    # Traverses the discovered longest common subsequences between +self+ and

    # +other+ using the alternate, balanced algorithm. See

    # Diff::LCS#traverse_balanced.

  def traverse_balanced(other, callbacks = nil, &block)

    traverse_balanced(self, other, callbacks || DiffX::LCS::YieldingCallbacks,

                      &block)

  end

    # Attempts to patch a copy of +self+ with the provided +patchset+. See

    # Diff::LCS#patch.

  def patch(patchset)

    DiffX::LCS::patch(self.dup, patchset)

  end

    # Attempts to unpatch a copy of +self+ with the provided +patchset+.

    # See Diff::LCS#patch.

  def unpatch(patchset)

    DiffX::LCS::unpatch(self.dup, patchset)

  end

    # Attempts to patch +self+ with the provided +patchset+. See

    # Diff::LCS#patch!. Does no autodiscovery.

  def patch!(patchset)

    DiffX::LCS::patch!(self, patchset)

  end

    # Attempts to unpatch +self+ with the provided +patchset+. See

    # Diff::LCS#unpatch. Does no autodiscovery.

  def unpatch!(patchset)

    DiffX::LCS::unpatch!(self, patchset)

  end

end

module DiffX::LCS

  class << self

      # Given two sequenced Enumerables, LCS returns an Array containing their

      # longest common subsequences.

      #

      #   lcs = Diff::LCS.LCS(seq1, seq2)

      #

      # This array whose contents is such that:

      #

      #   lcs.each_with_index do |ee, ii|

      #     assert(ee.nil? || (seq1[ii] == seq2[ee]))

      #   end

      #

      # If a block is provided, the matching subsequences will be yielded from

      # +seq1+ in turn and may be modified before they are placed into the

      # returned Array of subsequences.

    def LCS(seq1, seq2, &block) #:yields seq1[ii] for each matched:

      matches = DiffX::LCS.__lcs(seq1, seq2)

      ret = []

      matches.each_with_index do |ee, ii|

        unless matches[ii].nil?

          if block_given?

            ret << (yield seq1[ii])

          else

            ret << seq1[ii]

          end

        end

      end

      ret

    end

      # Diff::LCS.diff computes the smallest set of additions and deletions

      # necessary to turn the first sequence into the second, and returns a

      # description of these changes.

      # 

      # See Diff::LCS::DiffCallbacks for the default behaviour. An alternate

      # behaviour may be implemented with Diff::LCS::ContextDiffCallbacks.

      # If a Class argument is provided for +callbacks+, #diff will attempt

      # to initialise it. If the +callbacks+ object (possibly initialised)

      # responds to #finish, it will be called.

    def diff(seq1, seq2, callbacks = nil, &block) # :yields diff changes:

      callbacks ||= DiffX::LCS::DiffCallbacks

      if callbacks.kind_of?(Class)

        cb = callbacks.new rescue callbacks

        callbacks = cb

      end

      traverse_sequences(seq1, seq2, callbacks)

      callbacks.finish if callbacks.respond_to?(:finish)

      if block_given?

        res = callbacks.diffs.map do |hunk|

          if hunk.kind_of?(Array)

            hunk = hunk.map { |block| yield block }

          else

            yield hunk

          end

        end

        res

      else

        callbacks.diffs

      end

    end

      # Diff::LCS.sdiff computes all necessary components to show two sequences

      # and their minimized differences side by side, just like the Unix

      # utility <em>sdiff</em> does:

      #

      #     old        <     -

      #     same             same

      #     before     |     after

      #     -          >     new

      #

      # See Diff::LCS::SDiffCallbacks for the default behaviour. An alternate

      # behaviour may be implemented with Diff::LCS::ContextDiffCallbacks. If

      # a Class argument is provided for +callbacks+, #diff will attempt to

      # initialise it. If the +callbacks+ object (possibly initialised)

      # responds to #finish, it will be called.

    def sdiff(seq1, seq2, callbacks = nil, &block) #:yields diff changes:

      callbacks ||= DiffX::LCS::SDiffCallbacks

      if callbacks.kind_of?(Class)

        cb = callbacks.new rescue callbacks

        callbacks = cb

      end

      traverse_balanced(seq1, seq2, callbacks)

      callbacks.finish if callbacks.respond_to?(:finish)

      if block_given?

        res = callbacks.diffs.map do |hunk|

          if hunk.kind_of?(Array)

            hunk = hunk.map { |block| yield block }

          else

            yield hunk

          end

        end

        res

      else

        callbacks.diffs

      end

    end

      # Diff::LCS.traverse_sequences is the most general facility provided by this

      # module; +diff+ and +LCS+ are implemented as calls to it.

      #

      # The arguments to #traverse_sequences are the two sequences to

      # traverse, and a callback object, like this:

      #

      #   traverse_sequences(seq1, seq2, Diff::LCS::ContextDiffCallbacks.new)

      #

      # #diff is implemented with #traverse_sequences.

      #

      # == Callback Methods

      # Optional callback methods are <em>emphasized</em>.

      #

      # callbacks#match::               Called when +a+ and +b+ are pointing

      #                                 to common elements in +A+ and +B+.

      # callbacks#discard_a::           Called when +a+ is pointing to an

      #                                 element not in +B+.

      # callbacks#discard_b::           Called when +b+ is pointing to an

      #                                 element not in +A+.

      # <em>callbacks#finished_a</em>:: Called when +a+ has reached the end of

      #                                 sequence +A+.

      # <em>callbacks#finished_b</em>:: Called when +b+ has reached the end of

      #                                 sequence +B+.

      #

      # == Algorithm

      #       a---+

      #           v

      #       A = a b c e h j l m n p

      #       B = b c d e f j k l m r s t

      #           ^

      #       b---+

      #

      # If there are two arrows (+a+ and +b+) pointing to elements of

      # sequences +A+ and +B+, the arrows will initially point to the first

      # elements of their respective sequences. #traverse_sequences will

      # advance the arrows through the sequences one element at a time,

      # calling a method on the user-specified callback object before each

      # advance. It will advance the arrows in such a way that if there are

      # elements <tt>A[ii]</tt> and <tt>B[jj]</tt> which are both equal and

      # part of the longest common subsequence, there will be some moment

      # during the execution of #traverse_sequences when arrow +a+ is pointing

      # to <tt>A[ii]</tt> and arrow +b+ is pointing to <tt>B[jj]</tt>. When

      # this happens, #traverse_sequences will call <tt>callbacks#match</tt>

      # and then it will advance both arrows.

      #

      # Otherwise, one of the arrows is pointing to an element of its sequence

      # that is not part of the longest common subsequence.

      # #traverse_sequences will advance that arrow and will call

      # <tt>callbacks#discard_a</tt> or <tt>callbacks#discard_b</tt>, depending

      # on which arrow it advanced. If both arrows point to elements that are

      # not part of the longest common subsequence, then #traverse_sequences

      # will advance one of them and call the appropriate callback, but it is

      # not specified which it will call.

      #

      # The methods for <tt>callbacks#match</tt>, <tt>callbacks#discard_a</tt>,

      # and <tt>callbacks#discard_b</tt> are invoked with an event comprising

      # the action ("=", "+", or "-", respectively), the indicies +ii+ and

      # +jj+, and the elements <tt>A[ii]</tt> and <tt>B[jj]</tt>. Return

      # values are discarded by #traverse_sequences.

      #

      # === End of Sequences

      # If arrow +a+ reaches the end of its sequence before arrow +b+ does,

      # #traverse_sequence try to call <tt>callbacks#finished_a</tt> with the

      # last index and element of +A+ (<tt>A[-1]</tt>) and the current index

      # and element of +B+ (<tt>B[jj]</tt>). If <tt>callbacks#finished_a</tt>

      # does not exist, then <tt>callbacks#discard_b</tt> will be called on

      # each element of +B+ until the end of the sequence is reached (the call

      # will be done with <tt>A[-1]</tt> and <tt>B[jj]</tt> for each element).

      #

      # If +b+ reaches the end of +B+ before +a+ reaches the end of +A+,

      # <tt>callbacks#finished_b</tt> will be called with the current index

      # and element of +A+ (<tt>A[ii]</tt>) and the last index and element of

      # +B+ (<tt>A[-1]</tt>). Again, if <tt>callbacks#finished_b</tt> does not

      # exist on the callback object, then <tt>callbacks#discard_a</tt> will

      # be called on each element of +A+ until the end of the sequence is

      # reached (<tt>A[ii]</tt> and <tt>B[-1]</tt>).

      #

      # There is a chance that one additional <tt>callbacks#discard_a</tt> or

      # <tt>callbacks#discard_b</tt> will be called after the end of the

      # sequence is reached, if +a+ has not yet reached the end of +A+ or +b+

      # has not yet reached the end of +B+.

    def traverse_sequences(seq1, seq2, callbacks = DiffX::LCS::SequenceCallbacks, &block) #:yields change events:

      matches = DiffX::LCS.__lcs(seq1, seq2)

      run_finished_a = run_finished_b = false

      string = seq1.kind_of?(String)

      a_size = seq1.size

      b_size = seq2.size

      ai = bj = 0

      (0 .. matches.size).each do |ii|

        b_line = matches[ii]

        ax = string ? seq1[ii, 1] : seq1[ii]

        bx = string ? seq2[bj, 1] : seq2[bj]

        if b_line.nil?

          unless ax.nil?

            event = DiffX::LCS::ContextChange.new('-', ii, ax, bj, bx)

            event = yield event if block_given?

            callbacks.discard_a(event)

          end

        else

          loop do

            break unless bj < b_line

            bx = string ? seq2[bj, 1] : seq2[bj]

            event = DiffX::LCS::ContextChange.new('+', ii, ax, bj, bx)

            event = yield event if block_given?

            callbacks.discard_b(event)

            bj += 1

          end

          bx = string ? seq2[bj, 1] : seq2[bj]

          event = DiffX::LCS::ContextChange.new('=', ii, ax, bj, bx)

          event = yield event if block_given?

          callbacks.match(event)

          bj += 1

        end

        ai = ii

      end

      ai += 1

        # The last entry (if any) processed was a match. +ai+ and +bj+ point

        # just past the last matching lines in their sequences.

      while (ai < a_size) or (bj < b_size)

          # last A?

        if ai == a_size and bj < b_size

          if callbacks.respond_to?(:finished_a) and not run_finished_a

            ax = string ? seq1[-1, 1] : seq1[-1]

            bx = string ? seq2[bj, 1] : seq2[bj]

            event = DiffX::LCS::ContextChange.new('>', (a_size - 1), ax, bj, bx)

            event = yield event if block_given?

            callbacks.finished_a(event)

            run_finished_a = true

          else

            ax = string ? seq1[ai, 1] : seq1[ai]

            loop do

              bx = string ? seq2[bj, 1] : seq2[bj]

              event = DiffX::LCS::ContextChange.new('+', ai, ax, bj, bx)

              event = yield event if block_given?

              callbacks.discard_b(event)

              bj += 1

              break unless bj < b_size

            end

          end

        end

          # last B?

        if bj == b_size and ai < a_size

          if callbacks.respond_to?(:finished_b) and not run_finished_b

            ax = string ? seq1[ai, 1] : seq1[ai]

            bx = string ? seq2[-1, 1] : seq2[-1]

            event = DiffX::LCS::ContextChange.new('<', ai, ax, (b_size - 1), bx)

            event = yield event if block_given?

            callbacks.finished_b(event)

            run_finished_b = true

          else

            bx = string ? seq2[bj, 1] : seq2[bj]

            loop do

              ax = string ? seq1[ai, 1] : seq1[ai]

              event = DiffX::LCS::ContextChange.new('-', ai, ax, bj, bx)

              event = yield event if block_given?

              callbacks.discard_a(event)

              ai += 1

              break unless bj < b_size

            end

          end

        end

        if ai < a_size

          ax = string ? seq1[ai, 1] : seq1[ai]

          bx = string ? seq2[bj, 1] : seq2[bj]

          event = DiffX::LCS::ContextChange.new('-', ai, ax, bj, bx)

          event = yield event if block_given?

          callbacks.discard_a(event)

          ai += 1

        end

        if bj < b_size

          ax = string ? seq1[ai, 1] : seq1[ai]

          bx = string ? seq2[bj, 1] : seq2[bj]

          event = DiffX::LCS::ContextChange.new('+', ai, ax, bj, bx)

          event = yield event if block_given?

          callbacks.discard_b(event)

          bj += 1

        end

      end

    end

      # #traverse_balanced is an alternative to #traverse_sequences. It

      # uses a different algorithm to iterate through the entries in the

      # computed longest common subsequence. Instead of viewing the changes as

      # insertions or deletions from one of the sequences, #traverse_balanced

      # will report <em>changes</em> between the sequences. To represent a

      #

      # The arguments to #traverse_balanced are the two sequences to traverse

      # and a callback object, like this:

      #

      #   traverse_balanced(seq1, seq2, Diff::LCS::ContextDiffCallbacks.new)

      #

      # #sdiff is implemented with #traverse_balanced.

      #

      # == Callback Methods

      # Optional callback methods are <em>emphasized</em>.

      #

      # callbacks#match::               Called when +a+ and +b+ are pointing

      #                                 to common elements in +A+ and +B+.

      # callbacks#discard_a::           Called when +a+ is pointing to an

      #                                 element not in +B+.

      # callbacks#discard_b::           Called when +b+ is pointing to an

      #                                 element not in +A+.

      # <em>callbacks#change</em>::     Called when +a+ and +b+ are pointing

      #                                 to the same relative position, but

      #                                 <tt>A[a]</tt> and <tt>B[b]</tt> are

      #                                 not the same; a <em>change</em> has

      #                                 occurred.

      #

      # #traverse_balanced might be a bit slower than #traverse_sequences,

      # noticable only while processing huge amounts of data.

      #

      # The +sdiff+ function of this module is implemented as call to

      # #traverse_balanced.

      #

      # == Algorithm

      #       a---+

      #           v

      #       A = a b c e h j l m n p

      #       B = b c d e f j k l m r s t