support diffing for svn

 * Changed `--version` to use the optparse builtin support for it;
 * Changed `--numlines` to `--unified` because most diff tools use the latter for
   specifing number of context lines;
 * Added `-u` and `-L` to support svn calls to external diff tools.

The `-u` is a dummy option; it's there so that option parsing
doesn't choke whenever it is used. This is compatible with svn
and git.

Squash-merge of pharaujo's work in jeffkaufman#28.

Author: jeffkaufman

README.md

@@ -16,26 +16,32 @@ Show differences between files in a two column view.
 
 ### Options
 ```
-  -h, --help           show this help message and exit
-  --cols=COLS          specify the width of the screen. Autodetection is Unix
-                       only
-  --head=HEAD          consider only the first N lines of each file
-  --highlight          color by changing the background color instead of the
-                       foreground color.  Very fast, ugly, displays all
-                       changes
-  --line-numbers       generate output with line numbers
-  --no-bold            use non-bold colors; recommended for with solarized
-  --no-headers         don't label the left and right sides with their file
-                       names
-  --numlines=NUMLINES  how many lines of context to print; can't be combined
-                       with --whole-file
-  --recursive          recursively compare subdirectories
-  --show-all-spaces    color all non-matching whitespace including that which
-                       is not needed for drawing the eye to changes.  Slow,
-                       ugly, displays all changes
-  --version            print version and exit
-  --whole-file         show the whole file instead of just changed lines and
-                       context
+  --version             show program's version number and exit
+  -h, --help            show this help message and exit
+  -u, --patch           generate patch. This is always true, and only exists
+                        for compatibility
+  --cols=COLS           specify the width of the screen. Autodetection is
+                        Unix only
+  --head=HEAD           consider only the first N lines of each file
+  --highlight           color by changing the background color instead of the
+                        foreground color.  Very fast, ugly, displays all
+                        changes
+  --line-numbers        generate output with line numbers
+  --no-bold             use non-bold colors; recommended for with solarized
+  --no-headers          don't label the left and right sides with their file
+                        names
+  -U NUM, --unified=NUM, --numlines=NUM
+                        how many lines of context to print; can't be combined
+                        with --whole-file
+  --recursive           recursively compare subdirectories
+  --show-all-spaces     color all non-matching whitespace including that which
+                        is not needed for drawing the eye to changes.  Slow,
+                        ugly, displays all changes
+  --whole-file          show the whole file instead of just changed lines and
+                        context
+  -L LABELS, --label=LABELS
+                        override file labels with arbitrary tags. Use twice,
+                        one for each file
 ```
 
 
@@ -54,6 +60,16 @@ To install this as a tool you can use with git, copy
 git icdiff
 ```
 
+
+## Using with subversion
+
+To try it out, run:
+
+```sh
+svn diff --diff-cmd icdiff
+```
+
+
 ## License
 
 This file is derived from `difflib.HtmlDiff` which is under the [license](http://www.python.org/download/releases/2.6.2/license/).

icdiff

@@ -13,7 +13,7 @@ import os
 import sys
 import errno
 import difflib
-import optparse
+from optparse import Option, OptionParser
 import re
 import filecmp
 import unicodedata
@@ -386,12 +386,31 @@ class ConsoleDiff(object):
 def simple_colorize(s, chosen_color):
     return "%s%s%s" % (color_codes[chosen_color], s, color_codes["none"])
 
+
+class MultipleOption(Option):
+    ACTIONS = Option.ACTIONS + ("extend",)
+    STORE_ACTIONS = Option.STORE_ACTIONS + ("extend",)
+    TYPED_ACTIONS = Option.TYPED_ACTIONS + ("extend",)
+    ALWAYS_TYPED_ACTIONS = Option.ALWAYS_TYPED_ACTIONS + ("extend",)
+
+    def take_action(self, action, dest, opt, value, values, parser):
+        if action == "extend":
+            values.ensure_value(dest, []).append(value)
+        else:
+            Option.take_action(self, action, dest, opt, value, values, parser)
+
+
 def start():
     # If you change any of these, also update README.
-    parser = optparse.OptionParser(usage="usage: %prog [options] left_file right_file",
-                                   description="Show differences between files in a two column view.")
+    parser = OptionParser(usage="usage: %prog [options] left_file right_file",
+                          version="icdiff version %s" % __version__,
+                          description="Show differences between files in a two column view.",
+                          option_class=MultipleOption)
+    parser.add_option("-u", "--patch", default=True,
+                      action="store_true",
+                      help="generate patch. This is always true, and only exists for compatibility")
     parser.add_option("--cols", default=None,
-                      help="specify the width of the screen. Autodetection is Linux only")
+                      help="specify the width of the screen. Autodetection is Unix only")
     parser.add_option("--head", default=0,
                       help="consider only the first N lines of each file")
     parser.add_option("--highlight", default=False,
@@ -406,27 +425,26 @@ def start():
     parser.add_option("--no-headers", default=False,
                       action="store_true",
                       help="don't label the left and right sides with their file names")
-    parser.add_option("--numlines", default=5,
+    parser.add_option("-U", "--unified", "--numlines", default=5,
+                      metavar="NUM",
                       help="how many lines of context to print; can't be combined with --whole-file")
     parser.add_option("--recursive", default=False,
                       action="store_true",
                       help="recursively compare subdirectories")
     parser.add_option("--show-all-spaces", default=False,
                       action="store_true",
                       help="color all non-matching whitespace including that which is not needed for drawing the eye to changes.  Slow, ugly, displays all changes")
-    parser.add_option("--version", default=False,
-                      action="store_true",
-                      help="print version and exit")
     parser.add_option("--whole-file", default=False,
                       action="store_true",
                       help="show the whole file instead of just changed lines and context")
+    parser.add_option("-L", "--label",
+                      action="extend",
+                      type="string",
+                      dest='labels',
+                      help="override file labels with arbitrary tags. Use twice, one for each file")
 
     (options, args) = parser.parse_args()
 
-    if options.version:
-        print("icdiff version %s" % __version__)
-        sys.exit()
-
     if len(args) != 2:
         parser.print_help()
         sys.exit()
@@ -481,7 +499,14 @@ def diff_recursively(options, a, b):
         print_meta("File %s is a file while %s is a directory" % (a, b))
 
 def diff_files(options, a, b):
-    headers = a, b
+    if options.labels:
+        if len(options.labels) == 2:
+            headers = options.labels
+        else:
+            sys.stderr.write("error: to use arbitrary file labels, specify -L twice.\n")
+            sys.exit(1)
+    else:
+        headers = a, b
     if options.no_headers:
         headers = None, None
 
@@ -506,7 +531,7 @@ def diff_files(options, a, b):
     for line in cd.make_table(
             lines_a, lines_b, headers[0], headers[1],
             context=(not options.whole_file),
-            numlines=int(options.numlines)):
+            numlines=int(options.unified)):
         print(line)
         sys.stdout.flush()