[StGit PATCH 02/13] Clear up semantics of tree_status

["David Kågedal" <davidk@lysator.liu.se>]

The tree_status() function does a few slightly different things
depending on the arguments.  This patch adds checks that the arguments
are consistent and that the returned value looks good.

It also changes the semantics slightly.  If the 'files' parameter is
None, it will run status on all files.  If 'files' is a list, it will
run status on only those files.  This changes two things:

 1) If 'files' is the empty list, it will run status on no files.
 2) It 'files' is a list, it will never return the status for other files

Clearing this up will make it easier to understand code that is using
this function.

Signed-off-by: David Kågedal <davidk@lysator.liu.se>
---

 stgit/commands/status.py |    3 +++
 stgit/git.py             |   44 +++++++++++++++++++++++---------------------
 2 files changed, 26 insertions(+), 21 deletions(-)


diff --git a/stgit/commands/status.py b/stgit/commands/status.py
index 156552b..de88ba0 100644
--- a/stgit/commands/status.py
+++ b/stgit/commands/status.py
@@ -82,6 +82,9 @@ def func(parser, options, args):
         else:
             diff_flags = []
 
+        # No args means all files
+        if not args:
+            args = None
         git.status(args, options.modified, options.new, options.deleted,
                    options.conflict, options.unknown, options.noexclude,
                    diff_flags = diff_flags)
diff --git a/stgit/git.py b/stgit/git.py
index 539d699..8dda1ed 100644
--- a/stgit/git.py
+++ b/stgit/git.py
@@ -167,15 +167,20 @@ def exclude_files():
 
 def tree_status(files = None, tree_id = 'HEAD', unknown = False,
                   noexclude = True, verbose = False, diff_flags = []):
-    """Returns a list of pairs - (status, filename)
+    """Get the status of all changed files, or of a selected set of
+    files. Returns a list of pairs - (status, filename).
+
+    If 'files' is None, it will check all files, and optionally all
+    unknown files.  If 'files' is a list, it will only check the files
+    in the list.
     """
+    assert files == None or not unknown
+
     if verbose:
         out.start('Checking for changes in the working directory')
 
     refresh_index()
 
-    if not files:
-        files = []
     cache_files = []
 
     # unknown files
@@ -197,11 +202,14 @@ def tree_status(files = None, tree_id = 'HEAD', unknown = False,
     conflicts = get_conflicts()
     if not conflicts:
         conflicts = []
-    cache_files += [('C', filename) for filename in conflicts]
+    cache_files += [('C', filename) for filename in conflicts
+                    if files == None or filename in files]
 
     # the rest
-    for line in GRun('git-diff-index', *(diff_flags + [tree_id, '--'] + files)
-                     ).output_lines():
+    args = diff_flags + [tree_id]
+    if files != None:
+        args += ['--'] + files
+    for line in GRun('git-diff-index', *args).output_lines():
         fs = tuple(line.rstrip().split(' ',4)[-1].split('\t',1))
         if fs[1] not in conflicts:
             cache_files.append(fs)
@@ -209,6 +217,7 @@ def tree_status(files = None, tree_id = 'HEAD', unknown = False,
     if verbose:
         out.done()
 
+    assert files == None or set(f for s,f in cache_files) <= set(files)
     return cache_files
 
 def local_changes(verbose = True):
@@ -538,9 +547,6 @@ def committer():
 def update_cache(files = None, force = False):
     """Update the cache information for the given files
     """
-    if not files:
-        files = []
-
     cache_files = tree_status(files, verbose = False)
 
     # everything is up-to-date
@@ -569,8 +575,6 @@ def commit(message, files = None, parents = None, allowempty = False,
            committer_name = None, committer_email = None):
     """Commit the current tree to repository
     """
-    if not files:
-        files = []
     if not parents:
         parents = []
 
@@ -712,14 +716,13 @@ def status(files = None, modified = False, new = False, deleted = False,
            diff_flags = []):
     """Show the tree status
     """
-    if not files:
-        files = []
-
-    cache_files = tree_status(files, unknown = True, noexclude = noexclude,
-                                diff_flags = diff_flags)
-    all = not (modified or new or deleted or conflict or unknown)
+    cache_files = tree_status(files,
+                              unknown = (files == None),
+                              noexclude = noexclude,
+                              diff_flags = diff_flags)
+    filtered = (modified or new or deleted or conflict or unknown)
 
-    if not all:
+    if filtered:
         filestat = []
         if modified:
             filestat.append('M')
@@ -735,9 +738,8 @@ def status(files = None, modified = False, new = False, deleted = False,
         cache_files = [x for x in cache_files if x[0] in filestat]
 
     for fs in cache_files:
-        if files and not fs[1] in files:
-            continue
-        if all:
+        assert files == None or fs[1] in files
+        if not filtered:
             out.stdout('%s %s' % (fs[0], fs[1]))
         else:
             out.stdout('%s' % fs[1])