[meld] Add Differ API for checking whether diffs include non-conflict chunks

[Kai Willadsen <kaiw src gnome org>]

commit a5e31634e2591cb5d79746d99baf3f1b82dfbf78
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Mon May 17 17:40:22 2010 +1000

    Add Differ API for checking whether diffs include non-conflict chunks
    
    For sensitivity setting of (upcoming) merge-all actions, we need to know
    whether a given pair of sequences have mergeable (i.e., non-conflicting)
    changes. This commit adds the necessary API to the Differ class.

 meld/diffutil.py |   20 ++++++++++++++++++++
 1 files changed, 20 insertions(+), 0 deletions(-)
---
diff --git a/meld/diffutil.py b/meld/diffutil.py
index b1d4c7b..0533e05 100644
--- a/meld/diffutil.py
+++ b/meld/diffutil.py
@@ -86,6 +86,7 @@ class Differ(gobject.GObject):
         self._line_cache = [[], [], []]
         self.ignore_blanks = False
         self._initialised = False
+        self._has_mergeable_changes = (False, False)
 
     def _update_merge_cache(self, texts):
         if self.num_sequences == 3:
@@ -101,6 +102,14 @@ class Differ(gobject.GObject):
                                         self._consume_blank_lines(c[1], texts, 1, 2))
             self._merge_cache = [x for x in self._merge_cache if x != (None, None)]
 
+        mergeable0, mergeable1 = False, False
+        for (c0, c1) in self._merge_cache:
+            mergeable0 = mergeable0 or (c0 and c0[0] != 'conflict')
+            mergeable1 = mergeable1 or (c1 and c1[0] != 'conflict')
+            if mergeable0 and mergeable1:
+                break
+        self._has_mergeable_changes = (mergeable0, mergeable1)
+
         self._update_line_cache()
         self.emit("diffs-changed")
 
@@ -219,6 +228,17 @@ class Differ(gobject.GObject):
     def diff_count(self):
         return len(self._merge_cache)
 
+    def has_mergeable_changes(self, which):
+        if which == 0:
+            return (False, self._has_mergeable_changes[0])
+        elif which == 1:
+            if self.num_sequences == 2:
+                return (self._has_mergeable_changes[0], False)
+            else:
+                return self._has_mergeable_changes
+        else: # which == 2
+            return (self._has_mergeable_changes[1], False)
+
     def _change_sequence(self, which, sequence, startidx, sizechange, texts):
         diffs = self.diffs[which]
         lines_added = [0,0,0]