Highlight changed in individual lines in chunks that have the same number of adds/removes

kittens/diff/git.py

@@ -7,6 +7,7 @@
 import subprocess
 
 from .collect import lines_for_path
+from .diff_speedup import changed_center
 
 left_lines = right_lines = None
 
@@ -26,14 +27,14 @@ def run_diff(file1, file2, context=3):
 
 class Chunk:
 
-    __slots__ = ('is_context', 'left_start', 'right_start', 'left_count', 'right_count', 'is_change')
+    __slots__ = ('is_context', 'left_start', 'right_start', 'left_count', 'right_count', 'centers')
 
     def __init__(self, left_start, right_start, is_context=False):
         self.is_context = is_context
         self.left_start = left_start
         self.right_start = right_start
         self.left_count = self.right_count = 0
-        self.is_change = False
+        self.centers = None
 
     def add_line(self):
         self.right_count += 1
@@ -47,7 +48,7 @@ def context_line(self):
 
     def finalize(self):
         if not self.is_context and self.left_count == self.right_count:
-            self.is_change = True
+            self.centers = tuple(changed_center(left_lines[self.left_start + i], right_lines[self.right_start + i]) for i in range(self.left_count))
 
     def __repr__(self):
         return 'Chunk(is_context={}, left_start={}, left_count={}, right_start={}, right_count={})'.format(
@@ -183,16 +184,17 @@ def __call__(self, context=3):
             jobs = {executor.submit(run_diff, key, self.jmap[key], context): key for key in self.jobs}
             for future in concurrent.futures.as_completed(jobs):
                 key = jobs[future]
+                left_path, right_path = key, self.jmap[key]
                 try:
                     ok, returncode, output = future.result()
                 except FileNotFoundError as err:
                     return 'Could not find the {} executable. Is it in your PATH?'.format(err.filename)
                 except Exception as e:
-                    return 'Running git diff for {} vs. {} generated an exception: {}'.format(key[0], key[1], e)
+                    return 'Running git diff for {} vs. {} generated an exception: {}'.format(left_path, right_path, e)
                 if not ok:
-                    return output + '\nRunning git diff for {} vs. {} failed'.format(key[0], key[1])
-                left_lines = lines_for_path(key[0])
-                right_lines = lines_for_path(key[1])
+                    return output + '\nRunning git diff for {} vs. {} failed'.format(left_path, right_path)
+                left_lines = lines_for_path(left_path)
+                right_lines = lines_for_path(right_path)
                 try:
                     patch = parse_patch(output)
                 except Exception:

kittens/diff/render.py

@@ -109,6 +109,14 @@ def formatted(text):
 filler_format = format_func('filler')
 hunk_margin_format = format_func('hunk_margin')
 hunk_format = format_func('hunk')
+highlight_map = {'remove': ('removed_highlight', 'removed'), 'add': ('added_highlight', 'added')}
+
+
+def highlight_boundaries(ltype):
+    s, e = highlight_map[ltype]
+    start = '\x1b[' + formats[s] + 'm'
+    stop = '\x1b[' + formats[e] + 'm'
+    return start, stop
 
 
 def title_lines(left_path, right_path, args, columns, margin_size):
@@ -137,6 +145,36 @@ def split_to_size(line, width):
         line = line[p:]
 
 
+def split_to_size_with_center(line, width, prefix_count, suffix_count, start, stop):
+    pos = state = 0
+    suffix_pos = len(line) - suffix_count
+    while line:
+        p = truncate_point_for_length(line, width)
+        if state is 0:
+            if pos + p > prefix_count:
+                state = 1
+                a, line = line[:p], line[p:]
+                if pos + p > suffix_pos:
+                    a = a[:suffix_pos - pos] + stop + a[suffix_pos - pos:]
+                    state = 2
+                yield a[:prefix_count - pos] + start + a[prefix_count - pos:]
+            else:
+                yield line[:p]
+                line = line[p:]
+        elif state is 1:
+            if pos + p > suffix_pos:
+                state = 2
+                a, line = line[:p], line[p:]
+                yield start + a[:suffix_pos - pos] + stop + a[suffix_pos - pos:]
+            else:
+                yield start + line[:p]
+                line = line[p:]
+        elif state is 2:
+            yield line[:p]
+            line = line[p:]
+        pos += p
+
+
 margin_bg_map = {'filler': filler_format, 'remove': removed_margin_format, 'add': added_margin_format, 'context': margin_format}
 text_bg_map = {'filler': filler_format, 'remove': removed_format, 'add': added_format, 'context': text_format}
 
@@ -174,8 +212,12 @@ def hunk_title(hunk_num, hunk, margin_size, available_cols):
     return m + hunk_format(place_in(t, available_cols))
 
 
-def render_half_line(line_number, src, ltype, margin_size, available_cols):
-    lines = split_to_size(src[line_number], available_cols)
+def render_half_line(line_number, src, ltype, margin_size, available_cols, changed_center):
+    if changed_center is not None and changed_center[0]:
+        start, stop = highlight_boundaries(ltype)
+        lines = split_to_size_with_center(src[line_number], available_cols, changed_center[0], changed_center[1], start, stop)
+    else:
+        lines = split_to_size(src[line_number], available_cols)
     line_number = str(line_number + 1)
     for line in lines:
         yield render_diff_line(line_number, line, ltype, margin_size, available_cols)
@@ -205,9 +247,13 @@ def lines_for_chunk(data, hunk_num, chunk, chunk_num):
             ref = Reference(data.left_path, HunkRef(hunk_num, chunk_num, i))
             ll, rl = [], []
             if i < chunk.left_count:
-                ll.extend(render_half_line(chunk.left_start + i, data.left_lines, 'remove', data.margin_size, data.available_cols))
+                ll.extend(render_half_line(
+                    chunk.left_start + i, data.left_lines, 'remove', data.margin_size,
+                    data.available_cols, None if chunk.centers is None else chunk.centers[i]))
             if i < chunk.right_count:
-                rl.extend(render_half_line(chunk.right_start + i, data.right_lines, 'add', data.margin_size, data.available_cols))
+                rl.extend(render_half_line(
+                    chunk.right_start + i, data.right_lines, 'add', data.margin_size,
+                    data.available_cols, None if chunk.centers is None else chunk.centers[i]))
             if i < common:
                 extra = len(ll) - len(rl)
                 if extra != 0:

kitty_tests/diff.py

@@ -21,3 +21,14 @@ def test_changed_center(self):
             pc, sc = changed_center(left, right)
             for src in (left, right):
                 self.assertEqual((prefix, suffix), (src[:pc], src[-sc:] if sc else ''))
+
+    def test_split_to_size(self):
+        from kittens.diff.render import split_to_size_with_center
+        for line, width, prefix_count, suffix_count, expected in [
+                ('abcdefgh', 20, 2, 3, ('abSScdeEEfgh',)),
+                ('abcdefgh', 20, 2, 0, ('abSScdefgh',)),
+                ('abcdefgh', 3, 2, 3, ('abSSc', 'SSdeEEf', 'gh')),
+                ('abcdefgh', 2, 4, 1, ('ab', 'cd', 'SSef', 'SSgEEh')),
+        ]:
+            self.ae(expected, tuple(split_to_size_with_center(
+                line, width, prefix_count, suffix_count, 'SS', 'EE')))