added back tab functionality

cat_win/util/editor.py

@@ -343,6 +343,24 @@ def _scroll_key_home(self) -> None:
         self.wpos.row = 0
         self.wpos.col = 0
 
+    def _key_btab(self, _) -> str:
+        c_row = self.window_content[self.cpos.row]
+        if c_row[:1] == '\t':
+            self.window_content[self.cpos.row] = c_row[1:]
+            self.cpos.col = max(self.cpos.col-1, 0)
+            return '\t'
+        if c_row[:4] == '    ':
+            self.window_content[self.cpos.row] = c_row[4:]
+            self.cpos.col = max(self.cpos.col-4, 0)
+            return '    '
+        return None
+
+    def _key_btab_reverse(self, tab) -> str:
+        c_row = self.window_content[self.cpos.row]
+        self.window_content[self.cpos.row] = tab + c_row
+        self.cpos.col += len(tab)
+        return tab
+
     def _key_string(self, wchars) -> str:
         """
         tries to append (a) char(s) to the screen.

cat_win/util/editorhelper.py

@@ -131,6 +131,9 @@
     # shift - pos/home
     b'KEY_SHOME'     : b'_scroll_key_home', # windows & xterm
 
+    # shift + tab
+    b'KEY_BTAB'      : b'_key_btab', # windows & xterm
+
     # default alnum key
     b'_key_string'  : b'_key_string',
     # history
@@ -152,7 +155,8 @@
     b'_key_dl'           : b'_key_string',
     b'_key_backspace'    : b'_key_string',
     b'_key_ctl_backspace': b'_key_string',
-    b'_key_string'         : b'_key_backspace',
+    b'_key_string'       : b'_key_backspace',
+    b'_key_btab'         : b'_key_btab_reverse',
 } # defines the counter action if the file has the same amount of lines
 
 REVERSE_ACTION_SIZE_CHANGE = {