diff kitten: Make the representation of tabs configurable

kittens/diff/config.py

@@ -6,7 +6,7 @@ import os
 
 from kitty.config_utils import (
     init_config, load_config as _load_config, merge_dicts, parse_config_base,
-    resolve_config, to_color
+    python_string, resolve_config, to_color
 )
 from kitty.constants import config_dir
 from kitty.rgb import color_as_sgr
@@ -50,6 +50,7 @@ def syntax_aliases(raw):
 type_map = {
     'syntax_aliases': syntax_aliases,
     'num_context_lines': int,
+    'replace_tab_by': python_string,
 }
 
 for name in (

kittens/diff/diff.conf

@@ -17,6 +17,9 @@ num_context_lines 3
 # is to search the system for either git or diff and use that, if found.
 diff_cmd auto
 
+# The string to replace tabs with. Default is to use four spaces.
+replace_tab_by \x20\x20\x20\x20
+
 # Colors
 foreground            black
 background            white

kittens/diff/main.py

@@ -19,7 +19,9 @@ from ..tui.handler import Handler
 from ..tui.images import ImageManager
 from ..tui.loop import Loop
 from ..tui.operations import styled
-from .collect import create_collection, data_for_path, set_highlight_data
+from .collect import (
+    create_collection, data_for_path, lines_for_path, set_highlight_data
+)
 from .config import init_config
 from .patch import Differ, set_diff_command
 from .render import ImageSupportWarning, LineRef, render_diff
@@ -397,6 +399,7 @@ def main(args):
         raise SystemExit('The items to be diffed should both be either directories or files. Comparing a directory to a file is not valid.')
     opts = init_config(args)
     set_diff_command(opts.diff_cmd)
+    lines_for_path.replace_tab_by = opts.replace_tab_by
 
     loop = Loop()
     handler = DiffHandler(args, opts, left, right)