delete_word_left and delete_word_right unexpected behaviour

[wohltat]

When deleting a word with delete_word_left (ctrl+backspace) or delete_word_right (ctrl+delete) the behavior is not like in other editor and in my opinion faulty.

• When deleting back over a linebreak with multiple lines, it deletes all the whitespace + linebreak + the previous word. In sublime text for example this would be 3 steps.
• Strange behavior around brackets
  • It sometimes stops before the last bracket. When there is a word in the bracket like [foo]
  • deletion of adjacent brackets is also strange. For example deleting back in foo bar []() gives foo even though there is a space in between.
  • When there are brackets as first characters in the console command line, then they cannot be deleted at all

[wohltat]

This was bothering me quite a lot. So i had to do something.

Here is an algorithm where i tried to copy the behavior of sublime text:
As far as i tested it, it is identical.

Basic idea is that there are 3 character groups. As long as the next character is of the same group the deletion continues. One preceding white-space is skipped so that it is removed together with the word.

import tkinter as tk

example_text = """

    start_index = text_widget.search(r'\w*\W?', cursor_index, backwards=True, regexp=True, stopindex='1.0')

    # If start_index is at the beginning of the text, move it to the beginning of the line
    if start_index == '':
        start_index = '1.0'
    else:
        start_index = text_widget.index(start_index + "+1c")

    # Delete text between start of the word and cursor position
    text_widget.delete(start_index, cursor_index)

# Example usage:
def on_ctrl_backspace(event):
    delete_word_left(text_widget)
    asdasdf
        aaaaa\tasdf\t \tfsdf\t\tsdksd\t     
    .)(=.,)[]$&/()''""....{} asdf§sadf
"""

def char_group(c):
    # group 1 = whitespaces, group 2 = symbols, group 3 = alphanum
    group2_chars = '!"#$%&\'()*+,-./:;<=>?@[\\]^`{|}~'
    if c.isspace(): return 1
    if c in group2_chars: return 2
    return 3

def delete_word_left(text_widget):
    # Get current cursor position
    cursor_index = text_widget.index(tk.INSERT)
    line_start_index = text_widget.index(cursor_index + " linestart")

    # get the current line and search from the end
    line = text_widget.get(line_start_index, tk.INSERT)
    cur_index = len(line)-1

    # step at least one whitespace at the beginning
    if line and line[cur_index].isspace():	
        cur_index -= 1 

    last_char_group = None 
    for cur_char in reversed(line[:cur_index+1]):
        cur_char_group = char_group(cur_char)
        if last_char_group and last_char_group != cur_char_group:
            break
        last_char_group = cur_char_group
        cur_index -= 1

    start_index = text_widget.index(line_start_index +  f" + {cur_index+2} chars")
    text_widget.delete(start_index, cursor_index)

def delete_word_right(text_widget):
    # Get current cursor position
    cursor_index = text_widget.index(tk.INSERT)
    line_end_index = text_widget.index(cursor_index + " lineend")

    # get the current line and search from the end
    line = text_widget.get(tk.INSERT, line_end_index)
    cur_index = 0

    # step at least one whitespace at the beginning
    if line and line[cur_index].isspace():	
        cur_index += 1 

    last_char_group = None 
    for cur_char in line[cur_index:]:
        cur_char_group = char_group(cur_char)
        # print(f'{cur_index=} {cur_char=} {cur_char_group=} {last_char_group=}')
        if last_char_group and last_char_group != cur_char_group:
            break
        last_char_group = cur_char_group
        cur_index += 1

    end_index = text_widget.index(cursor_index +  f" + {cur_index-1} chars")
    text_widget.delete(cursor_index, end_index)

def on_ctrl_backspace(event):
    delete_word_left(text_widget)

def on_ctrl_delete(event):
    delete_word_right(text_widget)

root = tk.Tk() 
text_widget = tk.Text(root)
text_widget.insert(tk.END, example_text)
text_widget.pack()
text_widget.focus()
text_widget.bind("<Control-BackSpace>", on_ctrl_backspace)
text_widget.bind("<Control-Delete>", on_ctrl_delete)

root.mainloop()