[Patch] Support for multiple revisions for diff command

[Michael Ellerman]

Hi Martin,

This is a implementation of 'bzr diff -r foo -r2 bar'. I opted against using
the -r option twice because it's kind of ambiguous, and it seemed kind of
hard given the current option parsing scheme :D

Hmm, is it a feature or a "feature" that diff accepts (some) negative values
for revision number? It is kind of cool.

It's a little counter intertuitive (perhaps) but to get the diff for revno
440 you have to run 'bzr diff -r 439 -r2 440'.

cheers

*** modified file 'bzrlib/commands.py'
--- bzrlib/commands.py 
+++ bzrlib/commands.py 
@@ -425,8 +425,6 @@
     If files are listed, only the changes in those files are listed.
     Otherwise, all changes for the tree are listed.
 
-    TODO: Given two revision arguments, show the difference between them.
-
     TODO: Allow diff across branches.
 
     TODO: Option to use external diff command; could be GNU diff, wdiff,
@@ -444,13 +442,13 @@
     """
     
     takes_args = ['file*']
-    takes_options = ['revision']
+    takes_options = ['revision', 'target-revision']
     aliases = ['di']
 
-    def run(self, revision=None, file_list=None):
+    def run(self, revision=None, target_revision=None, file_list=None):
         from bzrlib.diff import show_diff
     
-        show_diff(Branch('.'), revision, file_list)
+        show_diff(Branch('.'), revision, target_revision, file_list)
 
 
         
@@ -861,7 +859,6 @@
 ######################################################################
 # main routine
 
-
 # list of all available options; the rhs can be either None for an
 # option that takes no argument, or a constructor function that checks
 # the type.
@@ -872,6 +869,7 @@
     'message':                unicode,
     'profile':                None,
     'revision':               int,
+    'target-revision':        int,
     'show-ids':               None,
     'timezone':               str,
     'verbose':                None,
@@ -883,6 +881,7 @@
     'm':                      'message',
     'F':                      'file', 
     'r':                      'revision',
+    'r2':                     'target-revision',
     'v':                      'verbose',
 }
 

*** modified file 'bzrlib/diff.py'
--- bzrlib/diff.py 
+++ bzrlib/diff.py 
@@ -140,15 +140,18 @@
 
 
 
-def show_diff(b, revision, file_list):
+def show_diff(b, revision, target_revision, file_list):
     import difflib, sys, types
     
     if revision == None:
         old_tree = b.basis_tree()
     else:
         old_tree = b.revision_tree(b.lookup_revision(revision))
-        
-    new_tree = b.working_tree()
+
+    if target_revision == None:
+        new_tree = b.working_tree()
+    else:
+        new_tree = b.revision_tree(b.lookup_revision(target_revision))
 
     # TODO: Options to control putting on a prefix or suffix, perhaps as a format string
     old_label = ''

*** modified file 'testbzr'
--- testbzr
+++ testbzr
@@ -281,6 +281,11 @@
     f.close()

     runcmd('bzr commit -F msg.tmp')
+
+    runcmd('bzr diff -r 0 -r2 1')
+
+    out = backtick('bzr diff -r 0 -r2 1').split('\n')[0]
+    assert out == "*** added file 'hello.txt'"

     assert backtick('bzr revno') == '5\n'
     runcmd('bzr export -r 5 export-5.tmp')