rename old_start and new_start to be more understandable

pydiffchecker/line_shift_checker.py

@@ -33,18 +33,26 @@ class LineShiftChecker:
         return file_list
 
     def __get_shifted_lines_in_file(self, file_info) -> 'Dict[str, str | None]':
-        lines_in_source_file = self.__count_lines_in_source_file(file_info['src'])
-        process_output = subprocess_readlines(['git', 'diff', f'-U{lines_in_source_file}',
+        process_output = subprocess_readlines(['git', 'diff',
                                                self.revision_since, self.revision_until, '--',
                                                file_info['src'], file_info['dst']])
 
-        diff_started = False
         shifted_lines = {}
+        src_line_index = 1
+        dst_line_index = 1
+        diff_started = False
         for line in process_output:
             matches = re.search(LineShiftChecker.DIFF_BLOCK_REGEX, line)
             if matches:
-                old_start = int(matches.group(1))
-                new_start = int(matches.group(3))
+                diff_block_src_start = int(matches.group(1))
+                diff_block_dst_start = int(matches.group(3))
+
+                # fill shifted lines between 2 diff blocks
+                for i in range(0, diff_block_src_start - src_line_index):
+                    shifted_lines[f'{file_info["src"]}:{src_line_index+i}'] = f'{file_info["dst"]}:{dst_line_index+i}'
+
+                src_line_index = diff_block_src_start
+                dst_line_index = diff_block_dst_start
                 diff_started = True
                 continue
 
@@ -52,20 +60,19 @@ class LineShiftChecker:
                 continue
 
             if line.startswith(' '):
-                shifted_lines[f'{file_info["src"]}:{old_start}'] = f'{file_info["dst"]}:{new_start}'
-                old_start += 1
-                new_start += 1
+                shifted_lines[f'{file_info["src"]}:{src_line_index}'] = f'{file_info["dst"]}:{dst_line_index}'
+                src_line_index += 1
+                dst_line_index += 1
             elif line.startswith('+'):
-                new_start += 1
+                dst_line_index += 1
             elif line.startswith('-'):
-                shifted_lines[f'{file_info["src"]}:{old_start}'] = None
-                old_start += 1
+                shifted_lines[f'{file_info["src"]}:{src_line_index}'] = None
+                src_line_index += 1
 
-        if not diff_started:
-            # it was a pure rename, so no diff blocks were returned,
-            # we just put the lines into the dict
-            shifted_lines = {f'{file_info["src"]}:{i}': f'{file_info["dst"]}:{i}'
-                             for i in range(0, lines_in_source_file)}
+        # fill shifted lines until end of file
+        lines_in_source_file = self.__count_lines_in_source_file(file_info['src'])
+        for i in range(0, lines_in_source_file - src_line_index + 1):
+            shifted_lines[f'{file_info["src"]}:{src_line_index+i}'] = f'{file_info["dst"]}:{dst_line_index+i}'
 
         assert lines_in_source_file == len(shifted_lines)