git p4: refactor diffOpts calculation

P4Submit.applyCommit()

To avoid recalculating the same diffOpts for each commit, move it
out of applyCommit() and into the top-level run().  Also fix a bug
in that code which interpreted the value of detectRenames as a
string rather than as a boolean.

[pw: fix documentation, rearrange code a bit]

Signed-off-by: Gary Gibbons <ggibbons@perforce.com>
Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-p4.txt

@@ -255,7 +255,7 @@ These options can be used to modify 'git p4 submit' behavior.
 	p4.  By default, this is the most recent p4 commit reachable
 	from 'HEAD'.
 
--M[<n>]::
+-M::
 	Detect renames.  See linkgit:git-diff[1].  Renames will be
 	represented in p4 using explicit 'move' operations.  There
 	is no corresponding option to detect copies, but there are
@@ -465,13 +465,15 @@ git-p4.useClientSpec::
 Submit variables
 ~~~~~~~~~~~~~~~~
 git-p4.detectRenames::
-	Detect renames.  See linkgit:git-diff[1].
+	Detect renames.  See linkgit:git-diff[1].  This can be true,
+	false, or a score as expected by 'git diff -M'.
 
 git-p4.detectCopies::
-	Detect copies.  See linkgit:git-diff[1].
+	Detect copies.  See linkgit:git-diff[1].  This can be true,
+	false, or a score as expected by 'git diff -C'.
 
 git-p4.detectCopiesHarder::
-	Detect copies harder.  See linkgit:git-diff[1].
+	Detect copies harder.  See linkgit:git-diff[1].  A boolean.
 
 git-p4.preserveUser::
 	On submit, re-author changes to reflect the git author,

git-p4.py

@@ -1046,27 +1046,8 @@ class P4Submit(Command, P4UserMap):
 
         (p4User, gitEmail) = self.p4UserForCommit(id)
 
-        if not self.detectRenames:
-            # If not explicitly set check the config variable
-            self.detectRenames = gitConfig("git-p4.detectRenames")
 
-        if self.detectRenames.lower() == "false" or self.detectRenames == "":
+        diff = read_pipe_lines("git diff-tree -r %s \"%s^\" \"%s\"" % (self.diffOpts, id, id))
-            diffOpts = ""
-        elif self.detectRenames.lower() == "true":
-            diffOpts = "-M"
-        else:
-            diffOpts = "-M%s" % self.detectRenames
-
-        detectCopies = gitConfig("git-p4.detectCopies")
-        if detectCopies.lower() == "true":
-            diffOpts += " -C"
-        elif detectCopies != "" and detectCopies.lower() != "false":
-            diffOpts += " -C%s" % detectCopies
-
-        if gitConfig("git-p4.detectCopiesHarder", "--bool") == "true":
-            diffOpts += " --find-copies-harder"
-
-        diff = read_pipe_lines("git diff-tree -r %s \"%s^\" \"%s\"" % (diffOpts, id, id))
         filesToAdd = set()
         filesToDelete = set()
         editedFiles = set()
@@ -1433,6 +1414,37 @@ class P4Submit(Command, P4UserMap):
         if self.preserveUser:
             self.checkValidP4Users(commits)
 
+        #
+        # Build up a set of options to be passed to diff when
+        # submitting each commit to p4.
+        #
+        if self.detectRenames:
+            # command-line -M arg
+            self.diffOpts = "-M"
+        else:
+            # If not explicitly set check the config variable
+            detectRenames = gitConfig("git-p4.detectRenames")
+
+            if detectRenames.lower() == "false" or detectRenames == "":
+                self.diffOpts = ""
+            elif detectRenames.lower() == "true":
+                self.diffOpts = "-M"
+            else:
+                self.diffOpts = "-M%s" % detectRenames
+
+        # no command-line arg for -C or --find-copies-harder, just
+        # config variables
+        detectCopies = gitConfig("git-p4.detectCopies")
+        if detectCopies.lower() == "false" or detectCopies == "":
+            pass
+        elif detectCopies.lower() == "true":
+            self.diffOpts += " -C"
+        else:
+            self.diffOpts += " -C%s" % detectCopies
+
+        if gitConfig("git-p4.detectCopiesHarder", "--bool") == "true":
+            self.diffOpts += " --find-copies-harder"
+
         while len(commits) > 0:
             commit = commits[0]
             commits = commits[1:]