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1"""
2Control character sets for terminal handling.
4This module provides the control character sets used by the width() function to handle terminal
5control characters.
6"""
8# Illegal C0/C1 control characters.
9# These raise ValueError in 'strict' mode.
10ILLEGAL_CTRL = frozenset(
11 chr(c) for c in (
12 list(range(0x01, 0x07)) + # SOH, STX, ETX (^C), EOT (^D), ENQ, ACK
13 list(range(0x10, 0x1b)) + # DLE through SUB (^Z)
14 list(range(0x1c, 0x20)) + # FS, GS, RS, US
15 [0x7f] + # DEL
16 list(range(0x80, 0xa0)) # C1 control characters
17 )
18)
20# Vertical movement control characters.
21# These raise ValueError in 'strict' mode (indeterminate horizontal position).
22VERTICAL_CTRL = frozenset({
23 '\x0a', # LF (line feed)
24 '\x0b', # VT (vertical tab)
25 '\x0c', # FF (form feed)
26})
28# Horizontal movement control characters.
29# These affect cursor position and are tracked in 'strict' and 'parse' modes.
30HORIZONTAL_CTRL = frozenset({
31 '\x08', # BS (backspace) - cursor left 1
32 '\x09', # HT (horizontal tab) - advance to next tab stop
33 '\x0d', # CR (carriage return) - cursor to column 0
34})
36# Terminal-valid zero-width control characters.
37# These are allowed in all modes (zero-width, no movement).
38ZERO_WIDTH_CTRL = frozenset({
39 '\x00', # NUL
40 '\x07', # BEL (bell)
41 '\x0e', # SO (shift out)
42 '\x0f', # SI (shift in)
43})
45# All control characters that need special handling (not regular printable).
46ALL_CTRL = ILLEGAL_CTRL | VERTICAL_CTRL | HORIZONTAL_CTRL | ZERO_WIDTH_CTRL | {'\x1b'}