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- """
- SGR (Select Graphic Rendition) state tracking for terminal escape sequences.
- This module provides functions for tracking and propagating terminal styling (bold, italic, colors,
- etc.) via public API propagate_sgr(), and its dependent functions, cut() and wrap(). It only has
- attributes necessary to perform its functions, eg 'RED' and 'BLUE' attributes are not defined.
- """
- from __future__ import annotations
- # std imports
- import re
- from enum import IntEnum
- from typing import TYPE_CHECKING, Iterator, NamedTuple
- if TYPE_CHECKING: # pragma: no cover
- from typing import Sequence
- class _SGR(IntEnum):
- """
- SGR (Select Graphic Rendition) parameter codes.
- References:
- - https://invisible-island.net/xterm/ctlseqs/ctlseqs.html
- - https://github.com/tehmaze/ansi/tree/master/ansi/colour
- """
- RESET = 0
- BOLD = 1
- DIM = 2
- ITALIC = 3
- UNDERLINE = 4
- BLINK = 5
- RAPID_BLINK = 6
- INVERSE = 7
- HIDDEN = 8
- STRIKETHROUGH = 9
- DOUBLE_UNDERLINE = 21
- BOLD_DIM_OFF = 22
- ITALIC_OFF = 23
- UNDERLINE_OFF = 24
- BLINK_OFF = 25
- INVERSE_OFF = 27
- HIDDEN_OFF = 28
- STRIKETHROUGH_OFF = 29
- FG_BLACK = 30
- FG_WHITE = 37
- FG_EXTENDED = 38
- FG_DEFAULT = 39
- BG_BLACK = 40
- BG_WHITE = 47
- BG_EXTENDED = 48
- BG_DEFAULT = 49
- FG_BRIGHT_BLACK = 90
- FG_BRIGHT_WHITE = 97
- BG_BRIGHT_BLACK = 100
- BG_BRIGHT_WHITE = 107
- # SGR sequence pattern: CSI followed by params (digits, semicolons, colons) ending with 'm'
- # Colons are used in ITU T.416 (ISO 8613-6) extended color format: 38:2::R:G:B
- # This colon format is less common than semicolon (38;2;R;G;B) but supported by kitty,
- # iTerm2, and newer VTE-based terminals.
- _SGR_PATTERN = re.compile(r'\x1b\[([\d;:]*)m')
- # Fast path: quick check if any SGR sequence exists
- _SGR_QUICK_CHECK = re.compile(r'\x1b\[[\d;:]*m')
- # Reset sequence
- _SGR_RESET = '\x1b[0m'
- class _SGRState(NamedTuple):
- """
- Track active SGR terminal attributes by category (immutable).
- :param bold: Bold attribute (SGR 1).
- :param dim: Dim/faint attribute (SGR 2).
- :param italic: Italic attribute (SGR 3).
- :param underline: Underline attribute (SGR 4).
- :param blink: Slow blink attribute (SGR 5).
- :param rapid_blink: Rapid blink attribute (SGR 6).
- :param inverse: Inverse/reverse attribute (SGR 7).
- :param hidden: Hidden/invisible attribute (SGR 8).
- :param strikethrough: Strikethrough attribute (SGR 9).
- :param double_underline: Double underline attribute (SGR 21).
- :param foreground: Foreground color as tuple of SGR params, or None for default.
- :param background: Background color as tuple of SGR params, or None for default.
- """
- bold: bool = False
- dim: bool = False
- italic: bool = False
- underline: bool = False
- blink: bool = False
- rapid_blink: bool = False
- inverse: bool = False
- hidden: bool = False
- strikethrough: bool = False
- double_underline: bool = False
- foreground: tuple[int, ...] | None = None
- background: tuple[int, ...] | None = None
- # Default state with no attributes set
- _SGR_STATE_DEFAULT = _SGRState()
- def _sgr_state_is_active(state: _SGRState) -> bool:
- """
- Return True if any attributes are set.
- :param state: The SGR state to check.
- :returns: True if any attribute differs from default.
- """
- return (state.bold or state.dim or state.italic or state.underline
- or state.blink or state.rapid_blink or state.inverse or state.hidden
- or state.strikethrough or state.double_underline
- or state.foreground is not None or state.background is not None)
- def _sgr_state_to_sequence(state: _SGRState) -> str:
- """
- Generate minimal SGR sequence to restore this state from reset.
- :param state: The SGR state to convert.
- :returns: SGR escape sequence string, or empty string if no attributes set.
- """
- if not _sgr_state_is_active(state):
- return ''
- # Map boolean attributes to their SGR codes
- bool_attrs = [
- (state.bold, '1'), (state.dim, '2'), (state.italic, '3'),
- (state.underline, '4'), (state.blink, '5'), (state.rapid_blink, '6'),
- (state.inverse, '7'), (state.hidden, '8'), (state.strikethrough, '9'),
- (state.double_underline, '21'),
- ]
- params = [code for active, code in bool_attrs if active]
- # Add color params (already formatted as tuples)
- if state.foreground is not None:
- params.append(';'.join(str(p) for p in state.foreground))
- if state.background is not None:
- params.append(';'.join(str(p) for p in state.background))
- return f'\x1b[{";".join(params)}m'
- def _parse_sgr_params(sequence: str) -> list[int | tuple[int, ...]]:
- r"""
- Parse SGR sequence and return list of parameter values.
- Handles compound sequences like ``\x1b[1;31;4m`` -> [1, 31, 4].
- Empty params (e.g., ``\x1b[m``) are treated as [0] (reset).
- Colon-separated extended colors like ``\x1b[38:2::255:0:0m`` are returned
- as tuples: [(38, 2, 255, 0, 0)].
- :param sequence: SGR escape sequence string.
- :returns: List of integer parameters or tuples for colon-separated colors.
- """
- match = _SGR_PATTERN.match(sequence)
- if not match:
- return []
- params_str = match.group(1)
- if not params_str:
- return [0] # \x1b[m is equivalent to \x1b[0m
- result: list[int | tuple[int, ...]] = []
- for param in params_str.split(';'):
- if ':' in param:
- # Colon-separated extended color (ITU T.416 format)
- # e.g., "38:2::255:0:0" or "38:2:1:255:0:0" (with colorspace)
- parts = [int(p) if p else 0 for p in param.split(':')]
- result.append(tuple(parts))
- else:
- result.append(int(param) if param else 0)
- return result
- def _parse_extended_color(
- params: Iterator[int | tuple[int, ...]], base: int
- ) -> tuple[int, ...] | None:
- """
- Parse extended color (256-color or RGB) from parameter iterator.
- :param params: Iterator of remaining SGR parameters (semicolon-separated format).
- :param base: Base code (38 for foreground, 48 for background).
- :returns: Color tuple like (38, 5, N) or (38, 2, R, G, B), or None if malformed.
- """
- try:
- mode = next(params)
- if isinstance(mode, tuple):
- return None # Unexpected tuple, colon format handled separately
- if mode == 5: # 256-color
- n = next(params)
- if isinstance(n, tuple):
- return None
- return (int(base), 5, n)
- if mode == 2: # RGB
- r, g, b = next(params), next(params), next(params)
- if isinstance(r, tuple) or isinstance(g, tuple) or isinstance(b, tuple):
- return None
- return (int(base), 2, r, g, b)
- except StopIteration:
- pass
- return None
- def _sgr_state_update(state: _SGRState, sequence: str) -> _SGRState:
- # pylint: disable=too-many-branches,too-complex,too-many-statements
- # NOTE: When minimum Python version is 3.10+, this can be simplified using match/case.
- """
- Parse SGR sequence and return new state with updates applied.
- :param state: Current SGR state.
- :param sequence: SGR escape sequence string.
- :returns: New SGRState with updates applied.
- """
- params_list = _parse_sgr_params(sequence)
- params = iter(params_list)
- for p in params:
- # Handle colon-separated extended colors (ITU T.416 format)
- if isinstance(p, tuple):
- if len(p) >= 2 and p[0] == _SGR.FG_EXTENDED:
- # Foreground: (38, 2, [colorspace,] R, G, B) or (38, 5, N)
- state = state._replace(foreground=p)
- elif len(p) >= 2 and p[0] == _SGR.BG_EXTENDED:
- # Background: (48, 2, [colorspace,] R, G, B) or (48, 5, N)
- state = state._replace(background=p)
- continue
- if p == _SGR.RESET:
- state = _SGR_STATE_DEFAULT
- # Attribute ON codes
- elif p == _SGR.BOLD:
- state = state._replace(bold=True)
- elif p == _SGR.DIM:
- state = state._replace(dim=True)
- elif p == _SGR.ITALIC:
- state = state._replace(italic=True)
- elif p == _SGR.UNDERLINE:
- state = state._replace(underline=True)
- elif p == _SGR.BLINK:
- state = state._replace(blink=True)
- elif p == _SGR.RAPID_BLINK:
- state = state._replace(rapid_blink=True)
- elif p == _SGR.INVERSE:
- state = state._replace(inverse=True)
- elif p == _SGR.HIDDEN:
- state = state._replace(hidden=True)
- elif p == _SGR.STRIKETHROUGH:
- state = state._replace(strikethrough=True)
- elif p == _SGR.DOUBLE_UNDERLINE:
- state = state._replace(double_underline=True)
- # Attribute OFF codes
- elif p == _SGR.BOLD_DIM_OFF:
- state = state._replace(bold=False, dim=False)
- elif p == _SGR.ITALIC_OFF:
- state = state._replace(italic=False)
- elif p == _SGR.UNDERLINE_OFF:
- state = state._replace(underline=False, double_underline=False)
- elif p == _SGR.BLINK_OFF:
- state = state._replace(blink=False, rapid_blink=False)
- elif p == _SGR.INVERSE_OFF:
- state = state._replace(inverse=False)
- elif p == _SGR.HIDDEN_OFF:
- state = state._replace(hidden=False)
- elif p == _SGR.STRIKETHROUGH_OFF:
- state = state._replace(strikethrough=False)
- # Basic colors (30-37, 40-47 standard; 90-97, 100-107 bright)
- elif (_SGR.FG_BLACK <= p <= _SGR.FG_WHITE
- or _SGR.FG_BRIGHT_BLACK <= p <= _SGR.FG_BRIGHT_WHITE):
- state = state._replace(foreground=(p,))
- elif (_SGR.BG_BLACK <= p <= _SGR.BG_WHITE
- or _SGR.BG_BRIGHT_BLACK <= p <= _SGR.BG_BRIGHT_WHITE):
- state = state._replace(background=(p,))
- elif p == _SGR.FG_DEFAULT:
- state = state._replace(foreground=None)
- elif p == _SGR.BG_DEFAULT:
- state = state._replace(background=None)
- # Extended colors (semicolon-separated format)
- elif p == _SGR.FG_EXTENDED:
- if color := _parse_extended_color(params, _SGR.FG_EXTENDED):
- state = state._replace(foreground=color)
- elif p == _SGR.BG_EXTENDED:
- if color := _parse_extended_color(params, _SGR.BG_EXTENDED):
- state = state._replace(background=color)
- return state
- def propagate_sgr(lines: Sequence[str]) -> list[str]:
- r"""
- Propagate SGR codes across wrapped lines.
- When text with SGR styling is wrapped across multiple lines, each line
- needs to be self-contained for proper display. This function:
- - Ends each line with ``\x1b[0m`` if styles are active (prevents bleeding)
- - Starts each subsequent line with the active style restored
- :param lines: List of text lines, possibly containing SGR sequences.
- :returns: List of lines with SGR codes propagated.
- Example::
- >>> propagate_sgr(['\x1b[31mhello', 'world\x1b[0m'])
- ['\x1b[31mhello\x1b[0m', '\x1b[31mworld\x1b[0m']
- This is useful in cases of making special editors and viewers, and is used for the
- default modes (propagate_sgr=True) of :func:`wcwidth.width` and :func:`wcwidth.clip`.
- When wrapping and clipping text containing SGR sequences, maybe a previous line enabled the BLUE
- color--if we are viewing *only* the line following, we would want the carry over the BLUE color,
- and all lines with sequences should end with terminating reset (``\x1b[0m``).
- """
- # Fast path: check if any line contains SGR sequences
- if not any(_SGR_QUICK_CHECK.search(line) for line in lines) or not lines:
- return list(lines)
- result: list[str] = []
- state = _SGR_STATE_DEFAULT
- for line in lines:
- # Prefix with restoration sequence if state is active
- prefix = _sgr_state_to_sequence(state)
- # Update state by processing all SGR sequences in this line
- for match in _SGR_PATTERN.finditer(line):
- state = _sgr_state_update(state, match.group())
- # Build output line
- output_line = prefix + line if prefix else line
- if _sgr_state_is_active(state):
- output_line = output_line + _SGR_RESET
- result.append(output_line)
- return result
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