[PATCH] Some minor fixes and improvements

[Piotr Piastucki <leech miranda gmail com>]

Hi,

I am sending the following 2 patches:
1) 0001-Workaround-for-line-numbers-covering-issue-610376.patch
This patch tries to work around the issue #610376, I have also attached 
it to the ticket in Bugzilla. It is rather a workaround than a real fix, 
but it seems to work reasonably well.
2) 0002-Myers-matcher-performance-improvements-and-cleanup.patch
Some minor performance improvements and cleaunp in Myers matcher code.

Comments and testing welcome.

Cheers,
Piotr

>From bacfe9835fabb7888c2a5b64ed75b4cd5cce7382 Mon Sep 17 00:00:00 2001
From: Piotr Piastucki <the_leech users berlios de>
Date: Fri, 25 Feb 2011 10:17:19 +0100
Subject: [PATCH 2/2] Myers matcher performance improvements and cleanup

This patch slightly simplifies the code of Myers matcher and improves the performance up to 10%.
---
 meld/matchers.py |   61 +++++++++++++++++++++++-------------------------------
 1 files changed, 26 insertions(+), 35 deletions(-)

diff --git a/meld/matchers.py b/meld/matchers.py
index 19507fe..ffd9f3a 100644
--- a/meld/matchers.py
+++ b/meld/matchers.py
@@ -105,12 +105,8 @@ class MyersSequenceMatcher(difflib.SequenceMatcher):
 
         # discard lines that do not match any line from the other file
         if n > 0 and m > 0:
-            aset = set()
-            bset = set()
-            for newline in b:
-                bset.add(newline)
-            for newline in a:
-                aset.add(newline)
+            aset = frozenset(a)
+            bset = frozenset(b)
             a2 = []
             b2 = []
             j = 0
@@ -204,7 +200,7 @@ class MyersSequenceMatcher(difflib.SequenceMatcher):
 
     def initialise(self):
         """
-        Optimized implementaion of the O(NP) algorithm described by Sun Wu, Udi Manber, Gene Myers, Webb Miller
+        Optimized implementation of the O(NP) algorithm described by Sun Wu, Udi Manber, Gene Myers, Webb Miller
         ("An O(NP) Sequence Comparison Algorithm", 1989)
         http://research.janelia.org/myers/Papers/np_diff.pdf
         """
@@ -214,10 +210,9 @@ class MyersSequenceMatcher(difflib.SequenceMatcher):
         n = len(b)
         middle = m + 1
         lastsnake = None
-        delta = n - m
-        dmin = min(0, delta)
-        dmax = max(0, delta)
-
+        delta = n - m + middle
+        dmin = min(middle, delta)
+        dmax = max(middle, delta)
         snakes = []
         if n > 0 and m > 0:
             size = n + m + 2
@@ -230,57 +225,53 @@ class MyersSequenceMatcher(difflib.SequenceMatcher):
                 # move along vertical edge
                 yv = -1
                 node = None
-                for k in range(dmin - p, delta, 1):
-                    km = k + middle
-                    if yv < fp[km + 1][0]:
-                        yv, node = fp[km + 1]
+                for km in range(dmin - p, delta, 1):
+                    t = fp[km + 1]
+                    if yv < t[0]:
+                        yv, node = t
                     else:
                         yv += 1
-                    x = yv - k
-                    snake = 0
+                    snake = x = yv - km + middle
                     while x < m and yv < n and a[x] == b[yv]:
                         x += 1
                         yv += 1
-                        snake += 1
-                    if snake:
+                    if x != snake:
+                        snake = x - snake
                         snakes.append((node, x - snake, yv - snake, snake))
                         node = len(snakes) - 1
                     fp[km] = (yv, node)
                 # move along horizontal edge
                 yh = -1
                 node = None
-                for k in range(dmax + p, delta, -1):
-                    km = k + middle
-                    if fp[km - 1][0] >= yh:
-                        yh, node = fp[km - 1]
+                for km in range(dmax + p, delta, -1):
+                    t = fp[km - 1]
+                    if yh <= t[0]:
+                        yh, node = t
                         yh += 1
-                    x = yh - k
-                    snake = 0
+                    snake = x = yh - km + middle
                     while x < m and yh < n and a[x] == b[yh]:
                         x += 1
                         yh += 1
-                        snake += 1
-                    if snake:
+                    if x != snake:
+                        snake = x - snake
                         snakes.append((node, x - snake, yh - snake, snake))
                         node = len(snakes) - 1
                     fp[km] = (yh, node)
                 # point on the diagonal that leads to the sink
-                km = delta + middle
                 if yv < yh:
-                    y, node = fp[km + 1]
+                    y, node = fp[delta + 1]
                 else:
-                    y, node = fp[km - 1]
+                    y, node = fp[delta - 1]
                     y += 1
-                x = y - delta
-                snake = 0
+                snake = x = y - delta + middle
                 while x < m and y < n and a[x] == b[y]:
                     x += 1
                     y += 1
-                    snake += 1
-                if snake:
+                if x != snake:
+                    snake = x - snake
                     snakes.append((node, x - snake, y - snake, snake))
                     node = len(snakes) - 1
-                fp[km] = (y, node)
+                fp[delta] = (y, node)
                 if y >= n:
                     lastsnake = node
                     break
-- 
1.7.1

>From 7ec9def900e4d756e9bcc6769f3693860e9adb8d Mon Sep 17 00:00:00 2001
From: Piotr Piastucki <the_leech users berlios de>
Date: Sat, 19 Feb 2011 12:12:58 +0100
Subject: [PATCH 1/2] Workaround for line numbers covering issue (#610376)

Both meld and gtksourceviewgutter handle expose-event to draw gutter content,
however, gtksourceviewgutter handler gets invoked first.
There seems to be no way to change the order of GTK signal handlers, so another
expose-event is emitted again after diff coloured block is drawn to trigger
gtksourceviewgutter handler.
---
 meld/filediff.py |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/meld/filediff.py b/meld/filediff.py
index f053218..e8b409e 100644
--- a/meld/filediff.py
+++ b/meld/filediff.py
@@ -230,6 +230,7 @@ class FileDiff(melddoc.MeldDoc, gnomeglade.Component):
         self.linediffer = self.differ()
         self.linediffer.ignore_blanks = self.prefs.ignore_blank_lines
         self.in_nested_action = False
+        self.in_nested_textview_gutter_expose = False
         self._inline_cache = set()
         self._cached_match = CachedSequenceMatcher()
         for buf in self.textbuffer:
@@ -1085,6 +1086,11 @@ class FileDiff(melddoc.MeldDoc, gnomeglade.Component):
         if event.window != textview.get_window(gtk.TEXT_WINDOW_TEXT) \
             and event.window != textview.get_window(gtk.TEXT_WINDOW_LEFT):
             return
+
+        if event.window == textview.get_window(gtk.TEXT_WINDOW_LEFT) and self.in_nested_textview_gutter_expose:
+            self.in_nested_textview_gutter_expose = False
+            return
+
         visible = textview.get_visible_rect()
         pane = self.textview.index(textview)
         area = event.area
@@ -1121,6 +1127,10 @@ class FileDiff(melddoc.MeldDoc, gnomeglade.Component):
             context.rectangle(0, ypos - visible.y, width, line_height)
             context.fill()
 
+        if event.window == textview.get_window(gtk.TEXT_WINDOW_LEFT):
+            self.in_nested_textview_gutter_expose = True
+            textview.emit("expose-event", event)
+
     def _get_filename_for_saving(self, title ):
         dialog = gtk.FileChooserDialog(title,
             parent=self.widget.get_toplevel(),
-- 
1.7.1