initial revision

COPYING

@@ -0,0 +1,339 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Lesser General Public License instead.)  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+  To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have.  You must make sure that they, too, receive or can get the
+source code.  And you must show them these terms so they know their
+rights.
+
+  We protect your rights with two steps: (1) copyright the software, and
+(2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+  Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software.  If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+  Finally, any free program is threatened constantly by software
+patents.  We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary.  To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+                    GNU GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License.  The "Program", below,
+refers to any such program or work, and a "work based on the Program"
+means either the Program or any derivative work under copyright law:
+that is to say, a work containing the Program or a portion of it,
+either verbatim or with modifications and/or translated into another
+language.  (Hereinafter, translation is included without limitation in
+the term "modification".)  Each licensee is addressed as "you".
+
+Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope.  The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
+Whether that is true depends on what the Program does.
+
+  1. You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
+conspicuously and appropriately publish on each copy an appropriate
+copyright notice and disclaimer of warranty; keep intact all the
+notices that refer to this License and to the absence of any warranty;
+and give any other recipients of the Program a copy of this License
+along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and
+you may at your option offer warranty protection in exchange for a fee.
+
+  2. You may modify your copy or copies of the Program or any portion
+of it, thus forming a work based on the Program, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+
+    a) You must cause the modified files to carry prominent notices
+    stating that you changed the files and the date of any change.
+
+    b) You must cause any work that you distribute or publish, that in
+    whole or in part contains or is derived from the Program or any
+    part thereof, to be licensed as a whole at no charge to all third
+    parties under the terms of this License.
+
+    c) If the modified program normally reads commands interactively
+    when run, you must cause it, when started running for such
+    interactive use in the most ordinary way, to print or display an
+    announcement including an appropriate copyright notice and a
+    notice that there is no warranty (or else, saying that you provide
+    a warranty) and that users may redistribute the program under
+    these conditions, and telling the user how to view a copy of this
+    License.  (Exception: if the Program itself is interactive but
+    does not normally print such an announcement, your work based on
+    the Program is not required to print an announcement.)
+
+These requirements apply to the modified work as a whole.  If
+identifiable sections of that work are not derived from the Program,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works.  But when you
+distribute the same sections as part of a whole which is a work based
+on the Program, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+  3. You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
+
+    a) Accompany it with the complete corresponding machine-readable
+    source code, which must be distributed under the terms of Sections
+    1 and 2 above on a medium customarily used for software interchange; or,
+
+    b) Accompany it with a written offer, valid for at least three
+    years, to give any third party, for a charge no more than your
+    cost of physically performing source distribution, a complete
+    machine-readable copy of the corresponding source code, to be
+    distributed under the terms of Sections 1 and 2 above on a medium
+    customarily used for software interchange; or,
+
+    c) Accompany it with the information you received as to the offer
+    to distribute corresponding source code.  (This alternative is
+    allowed only for noncommercial distribution and only if you
+    received the program in object code or executable form with such
+    an offer, in accord with Subsection b above.)
+
+The source code for a work means the preferred form of the work for
+making modifications to it.  For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable.  However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+  4. You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License.  Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+  5. You are not required to accept this License, since you have not
+signed it.  However, nothing else grants you permission to modify or
+distribute the Program or its derivative works.  These actions are
+prohibited by law if you do not accept this License.  Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
+
+  6. Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions.  You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+  7. If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all.  For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices.  Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+  8. If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded.  In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+  9. The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+Each version is given a distinguishing version number.  If the Program
+specifies a version number of this License which applies to it and "any
+later version", you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation.  If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+  10. If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission.  For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this.  Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+                            NO WARRANTY
+
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    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.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) year name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.

Makefile

@@ -0,0 +1,15 @@
+# Makefile for testing
+
+.PHONY: test single-udiff multi-udiff
+
+test: single-udiff multi-udiff
+
+single-udiff:
+	src/cdiff.py -t tests/single.udiff
+	src/cdiff.py -t tests/single.udiff | diff -u tests/single.udiff -
+
+multi-udiff:
+	src/cdiff.py -t tests/multi.udiff
+	src/cdiff.py -t tests/multi.udiff | diff -u tests/multi.udiff -
+
+# vim:set noet ts=8 sw=8:

README.md

@@ -0,0 +1,7 @@
+## About
+
+Diff viewer.
+
+## Usage
+
+TODO

src/cdiff.py

@@ -0,0 +1,390 @@
+#!/usr/bin/env python
+
+import sys
+import os
+import re
+
+
+class Hunk(object):
+
+    def __init__(self, hunk_header, old_addr, old_offset, new_addr, new_offset):
+        self.__hunk_header = hunk_header
+        self.__old_addr = old_addr
+        self.__old_offset = old_offset
+        self.__new_addr = new_addr
+        self.__new_offset = new_offset
+        self.__hunk_list = []   # 2-element group (attr, line)
+
+    def get_header(self):
+        return self.__hunk_header
+
+    def get_old_addr(self):
+        return (self.__old_addr, self.__old_offset)
+
+    def get_new_addr(self):
+        return (self.__new_addr, self.__new_offset)
+
+    def append(self, attr, line):
+        """attr: '-': old, '+': new, ' ': common"""
+        self.__hunk_list.append((attr, line))
+
+    def __iter__(self):
+        for hunk_line in self.__hunk_list:
+            yield hunk_line
+
+
+class Diff(object):
+
+    def __init__(self, headers, old_path, new_path, hunks):
+        self.__headers = headers
+        self.__old_path = old_path
+        self.__new_path = new_path
+        self.__hunks = hunks
+
+    def view_traditional(self, show_color):
+        out = []
+        if show_color:
+            color = None    # Use default
+            end_color = None
+        else:
+            color = 'none'  # No color
+            end_color = 'none'
+
+        for line in self.__headers:
+            out.append(self._view_header(line, color, end_color))
+
+        out.append(self._view_old_path(self.__old_path, color, end_color))
+        out.append(self._view_new_path(self.__new_path, color, end_color))
+
+        for hunk in self.__hunks:
+            out.append(self._view_hunk_header(hunk.get_header(), color,
+                end_color))
+            for (attr, line) in hunk:
+                if attr == '-':
+                    out.append(self._view_old(attr+line, color, end_color))
+                elif attr == '+':
+                    out.append(self._view_new(attr+line, color, end_color))
+                else:
+                    out.append(self._view_common(attr+line, color, end_color))
+
+        return ''.join(out)
+
+    def view_side_by_side(self, show_color, show_number, width):
+        """Do not really need to parse the hunks..."""
+        return 'TODO: show_color=%s, show_number=%s, width=%d' % (show_color,
+                show_number, width)
+
+    def _view_header(self, line, color=None, end_color=None):
+        if color is None:
+            color='cyan'
+        if end_color is None:
+            end_color = 'reset'
+        return self.__mark_color(line, color, end_color)
+
+    def _view_old_path(self, line, color=None, end_color=None):
+        if color is None:
+            color='yellow'
+        if end_color is None:
+            end_color = 'reset'
+        return self.__mark_color(line, color, end_color)
+
+    def _view_new_path(self, line, color=None, end_color=None):
+        if color is None:
+            color='yellow'
+        if end_color is None:
+            end_color = 'reset'
+        return self.__mark_color(line, color, end_color)
+
+    def _view_hunk_header(self, line, color=None, end_color=None):
+        if color is None:
+            color='lightblue'
+        if end_color is None:
+            end_color = 'reset'
+        return self.__mark_color(line, color, end_color)
+
+    def _view_old(self, line, color=None, end_color=None):
+        if color is None:
+            color='red'
+        if end_color is None:
+            end_color = 'reset'
+        return self.__mark_color(line, color, end_color)
+
+    def _view_new(self, line, color=None, end_color=None):
+        if color is None:
+            color='green'
+        if end_color is None:
+            end_color = 'reset'
+        return self.__mark_color(line, color, end_color)
+
+    def _view_common(self, line, color=None, end_color=None):
+        if color is None:
+            color='none'
+        if end_color is None:
+            end_color = 'none'
+        return self.__mark_color(line, color, end_color)
+
+    def __mark_color(self, text, start_code, end_code):
+        colors = {
+                'none'          : '',
+                'reset'         : '\x1b[0m',
+                'red'           : '\x1b[31m',
+                'green'         : '\x1b[32m',
+                'yellow'        : '\x1b[33m',
+                'blue'          : '\x1b[34m',
+                'cyan'          : '\x1b[36m',
+                'lightblue'     : '\x1b[1;34m',
+            }
+        return colors.get(start_code) + text + colors.get(end_code)
+
+
+class Udiff(Diff):
+
+    @staticmethod
+    def is_old_path(line):
+        return line.startswith('--- ')
+
+    @staticmethod
+    def is_new_path(line):
+        return line.startswith('+++ ')
+
+    @staticmethod
+    def is_hunk_header(line):
+        return line.startswith('@@ -')
+
+    @staticmethod
+    def is_old(line):
+        return line.startswith('-') and not Udiff.is_old_path(line)
+
+    @staticmethod
+    def is_new(line):
+        return line.startswith('+') and not Udiff.is_new_path(line)
+
+    @staticmethod
+    def is_common(line):
+        return line.startswith(' ')
+
+    @staticmethod
+    def is_eof(line):
+        # \ No newline at end of file
+        return line.startswith('\\')
+
+    @staticmethod
+    def is_header(line):
+        return re.match(r'^[^+@\\ -]', line)
+
+
+class DiffParser(object):
+
+    def __init__(self, stream):
+        for line in stream[:10]:
+            if line.startswith('+++ '):
+                self.__type = 'udiff'
+                break
+        else:
+            raise RuntimeError('unknown diff type')
+
+        try:
+            self.__diffs = self.__parse(stream)
+        except (AssertionError, IndexError):
+            raise RuntimeError('invalid patch format')
+
+
+    def get_diffs(self):
+        return self.__diffs
+
+    def __parse(self, stream):
+        if self.__type == 'udiff':
+            return self.__parse_udiff(stream)
+        else:
+            raise RuntimeError('unsupported diff format')
+
+    def __parse_udiff(self, stream):
+        """parse all diff lines here, construct a list of Udiff objects"""
+        out_diffs = []
+        headers = []
+        old_path = None
+        new_path = None
+        hunks = []
+        hunk = None
+
+        while stream:
+            if Udiff.is_header(stream[0]):
+                if headers and old_path:
+                    # Encounter a new header
+                    assert new_path is not None
+                    assert hunk is not None
+                    hunks.append(hunk)
+                    out_diffs.append(Diff(headers, old_path, new_path, hunks))
+                    headers = []
+                    old_path = None
+                    new_path = None
+                    hunks = []
+                    hunk = None
+                else:
+                    headers.append(stream.pop(0))
+
+            elif Udiff.is_old_path(stream[0]):
+                if old_path:
+                    # Encounter a new patch set
+                    assert new_path is not None
+                    assert hunk is not None
+                    hunks.append(hunk)
+                    out_diffs.append(Diff(headers, old_path, new_path, hunks))
+                    headers = []
+                    old_path = None
+                    new_path = None
+                    hunks = []
+                    hunk = None
+                else:
+                    old_path = stream.pop(0)
+
+            elif Udiff.is_new_path(stream[0]):
+                assert old_path is not None
+                assert new_path is None
+                new_path = stream.pop(0)
+
+            elif Udiff.is_hunk_header(stream[0]):
+                assert old_path is not None
+                assert new_path is not None
+                if hunk:
+                    # Encounter a new hunk header
+                    hunks.append(hunk)
+                    hunk = None
+                else:
+                    # @@ -3,7 +3,6 @@
+                    hunk_header = stream.pop(0)
+
+                    addr_info = hunk_header.split()[1]
+                    assert addr_info.startswith('-')
+                    old_addr = addr_info.split(',')[0]
+                    old_offset = addr_info.split(',')[1]
+
+                    addr_info = hunk_header.split()[2]
+                    assert addr_info.startswith('+')
+                    new_addr = addr_info.split(',')[0]
+                    new_offset = addr_info.split(',')[1]
+
+                    hunk = Hunk(hunk_header, old_addr, old_offset, new_addr,
+                            new_offset)
+
+            elif Udiff.is_old(stream[0]) or Udiff.is_new(stream[0]) or \
+                    Udiff.is_common(stream[0]):
+                assert old_path is not None
+                assert new_path is not None
+                assert hunk is not None
+                hunk_line = stream.pop(0)
+                hunk.append(hunk_line[0], hunk_line[1:])
+
+            elif Udiff.is_eof(stream[0]):
+                # ignore
+                stream.pop(0)
+
+            else:
+                raise RuntimeError('unknown patch format: %s' % stream[0])
+
+        # The last patch
+        if hunk:
+            hunks.append(hunk)
+        if old_path:
+            if new_path:
+                out_diffs.append(Diff(headers, old_path, new_path, hunks))
+            else:
+                raise RuntimeError('unknown patch format after "%s"' % old_path)
+        elif headers:
+            raise RuntimeError('unknown patch format: %s' % \
+                    ('\n'.join(headers)))
+
+        return out_diffs
+
+
+class DiffViewer(object):
+
+    def __init__(self, stream):
+        self.__diffs = DiffParser(stream).get_diffs()
+
+    def view(self, show_color=True, show_number=False, width=0,
+            traditional=False):
+        if traditional:
+            return self.__view_traditional(show_color)
+        else:
+            return self.__view_side_by_side(show_color, show_number, width)
+
+    def __view_traditional(self, show_color):
+        out = []
+        for diff in self.__diffs:
+            out.append(diff.view_traditional(show_color))
+        return out
+
+    def __view_side_by_side(self, show_color, show_number, width):
+        """width of 0 or negative means auto detect terminal width"""
+        out = []
+        for diff in self.__diffs:
+            out.append(diff.view_side_by_side(show_color, show_number, width))
+        return out
+
+
+if __name__ == '__main__':
+    import optparse
+    import subprocess
+
+    usage = '''
+    %(prog)s [options] [diff]
+
+    View diff (patch) file if given, otherwise read stdin''' % \
+            {'prog': os.path.basename(sys.argv[0])}
+
+    parser = optparse.OptionParser(usage)
+    parser.add_option('-c', '--color', metavar='on|off|auto', default='auto',
+            help='enforce color' 'on|off|auto, default is auto')
+    parser.add_option('-n', '--number', action='store_true',
+            help='show line number')
+    parser.add_option('-w', '--width', type='int', default=0,
+            help='set text width for each side')
+    parser.add_option('-t', '--traditional', action='store_true',
+            help=('show in traditional format other than default side-by-side '
+                  'mode (omit -n, -w)'))
+    opts, args = parser.parse_args()
+
+    if opts.color == 'yes':
+        show_color = True
+    elif opts.color == 'no':
+        show_color = False
+    elif opts.color == 'auto':
+        show_color = sys.stdout.isatty()
+    else:
+        sys.stderr.write('Invalid color mode, try --help option for usage\n')
+        sys.exit(1)
+
+    if opts.width < 0:
+        opts.width = 0
+
+    if len(args) >= 1:
+        diff_hdl = open(args[0], 'r')
+    elif sys.stdin.isatty():
+        sys.stderr.write('Try --help option for usage\n')
+        sys.exit(1)
+    else:
+        diff_hdl = sys.stdin
+
+    stream = diff_hdl.readlines()
+    if diff_hdl is not sys.stdin:
+        diff_hdl.close()
+
+    diffviewer = DiffViewer(stream)
+    view = diffviewer.view(show_color=show_color, show_number=opts.number,
+            width=opts.width, traditional=opts.traditional)
+
+    if sys.stdout.isatty():
+        # args stolen fron git source, see less(1)
+        # https://github.com/git/git/blob/master/pager.c
+        pager = subprocess.Popen(['less', '-FRSXK'],
+                stdin=subprocess.PIPE, stdout=sys.stdout)
+        pager.stdin.write(''.join(view))
+        pager.stdin.close()
+        pager.wait()
+    else:
+        sys.stdout.write(''.join(view))
+
+    sys.exit(0)
+
+# vim:set et sts=4 sw=4 tw=80:

tests/multi.udiff

@@ -0,0 +1,30 @@
+diff --git a/Makefile b/Makefile
+index 2dc65aa..4d698fc 100644
+--- a/Makefile
++++ b/Makefile
+@@ -2,9 +2,12 @@
+ 
+ .PHONY: test single
+ 
+-test: single
++test: single multi
+ 
+ single:
+ 	src/diffview.py -t tests/single.diff
+ 
++multi:
++	src/diffview.py -t tests/multi.diff
++
+ # vim:set noet ts=8 sw=8:
+diff --git a/README.md b/README.md
+index 39b5c84..1da3039 100644
+--- a/README.md
++++ b/README.md
+@@ -1,3 +1,7 @@
+ ## About
+ 
++Diff viewer.
++
+ ## Usage
++
++TODO

tests/single.udiff

@@ -0,0 +1,143 @@
+diff --git a/diffview b/diffview
+index 80ff9a2..f92c107 100755
+--- a/diffview
++++ b/diffview
+@@ -2,20 +2,26 @@
+ 
+ import sys
+ import os
++import re
+ 
+ 
+ class Diff(object):
+ 
+-    def __init__(self, diff_lines):
+-        self.__diff_lines = diff_lines
+-        self.__type = 'udiff'
++    def __init__(self):
++        pass
++
++
++class Udiff(Diff):
++
++    def __init__(self, patch):
++        self.__patch = patch
+ 
+     def view_traditional(self, show_color):
+         if show_color:
+-            for line in self.__diff_lines:
++            for line in self.__patch:
+                 sys.stdout.write(self.__colorize(line))
+         else:
+-            for line in self.__diff_lines:
++            for line in self.__patch:
+                 sys.stdout.write(line)
+ 
+     def view_side_by_side(self, show_color, show_number, width):
+@@ -27,47 +33,79 @@ class Diff(object):
+                 'red': '\x1b[31m',
+                 'green': '\x1b[32m',
+                 'yellow': '\x1b[33m',
++                'blue': '\x1b[34m',
+                 'cyan': '\x1b[36m',
+                 'none': '\x1b[0m',
++                'lightblue': '\x1b[1;34m',
+             }
+         return colors.get(start_code, 'none') + text + colors.get(end_code,
+                 'none')
+ 
+     def __colorize(self, line):
+-        if line.startswith('diff ') or line.startswith('--- ') or \
+-                line.startswith('+++ '):
++        if line.startswith('--- ') or line.startswith('+++ '):
+             return self.__mark_color(line, 'yellow')
+         elif line.startswith('@@ '):
+-            return self.__mark_color(line, 'cyan')
++            return self.__mark_color(line, 'lightblue')
+         elif line.startswith('-'):
+             return self.__mark_color(line, 'red')
+         elif line.startswith('+'):
+             return self.__mark_color(line, 'green')
++        elif not line.startswith(' '):
++            return self.__mark_color(line, 'cyan')
+         else:
+             return line
+ 
+ 
+ class DiffParser(object):
+ 
+-    def __init__(self, all_diff_lines):
+-        self.__all_diff_lines = all_diff_lines
++    def __init__(self, patch_set):
++        for line in patch_set[:10]:
++            if line.startswith('--- '):
++                self.__type = 'udiff'
++                break
++        else:
++            raise RuntimeError('unknown diff type')
++
++        self.__patch_set = patch_set
+ 
+     def parse(self):
+-        diffs = []
++        if self.__type == 'udiff':
++            return self.__parse_udiff()
+ 
+-        # parse all diff lines here, construct a Diff object for diff lines of
+-        # one file one time
+-        #
+-        diff_lines = self.__all_diff_lines
+-        diffs.append(Diff(diff_lines))
++    def __parse_udiff(self):
++        """parse all diff lines here, construct a list of Udiff objects"""
++        diffs = []
++        patch = []
++        saw_diff = False
++
++        while self.__patch_set:
++            line = self.__patch_set[0]
++            if re.match('^[+@ -]', line):
++                # see a diff line
++                saw_diff = True
++                patch.append(self.__patch_set.pop(0))
++            else:
++                # see a header line
++                if saw_diff:
++                    # a header line for new file
++                    diffs.append(Udiff(patch))
++                    patch = []
++                    saw_diff = False
++                else:
++                    # still header line for current file
++                    patch.append(self.__patch_set.pop(0))
++
++        # the last patch
++        if patch:
++            diffs.append(Udiff(patch))
+ 
+         return diffs
+ 
+ 
+ class DiffViewer(object):
+ 
+-    def __init__(self, all_diff_lines):
+-        self.__diffs = DiffParser(all_diff_lines).parse()
++    def __init__(self, patch_set):
++        self.__diffs = DiffParser(patch_set).parse()
+ 
+     def view(self, show_color=True, show_number=False, width=0, traditional=False):
+         if traditional:
+@@ -130,11 +168,11 @@ if __name__ == '__main__':
+     else:
+         diff_hdl = sys.stdin
+ 
+-    all_diff_lines = diff_hdl.readlines()
++    patch_set = diff_hdl.readlines()
+     if diff_hdl != sys.stdin:
+         diff_hdl.close()
+ 
+-    diffviewer = DiffViewer(all_diff_lines)
++    diffviewer = DiffViewer(patch_set)
+     diffviewer.view(show_color=show_color, show_number=opts.number,
+             width=opts.width, traditional=opts.traditional)
+