LeoVasanko
465206067b
Store the two-digit WS id (colored when stderr supports color, plain otherwise) in the ASGI scope state so user code can include it in its own log lines via websocket.state.logid. Move terminal helpers (use_color, strip_ansi, display width) into a new dependency-free fastapi_vue.tty module, absorbing termwidth.py, to keep imports one-directional and avoid the logging/accesslog cycle.
64 lines
2.1 KiB
Python
64 lines
2.1 KiB
Python
"""Terminal color detection, ANSI helpers, and display width calculation."""
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from __future__ import annotations
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import io
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import os
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import re
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import sys
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import unicodedata
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from contextlib import suppress
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ANSI_ESCAPE_RE = re.compile(r"\x1b\[[0-9;:]*[A-Za-z]")
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def strip_ansi(text: str) -> str:
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"""Remove ANSI escape codes from text."""
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return ANSI_ESCAPE_RE.sub("", text)
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def use_color(stream: io.TextIOBase = sys.stderr) -> bool:
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"""Test if the stream supports color codes."""
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if os.environ.get("NO_COLOR"): # Non empty means no (no-color.org)
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return False
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if os.environ.get("FORCE_COLOR", "") not in {"", "0"}: # force-color.org, node
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return True
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if hasattr(stream, "isatty") and stream.isatty():
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return True
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with suppress(KeyError, ValueError, OSError): # Journald does color (-ocat)
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dev, ino = map(int, os.environ["JOURNAL_STREAM"].split(":", 1))
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st = os.fstat(stream.fileno())
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return st.st_dev == dev and st.st_ino == ino
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return False
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def _is_wide(char: str) -> bool:
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"""Return True for characters rendered as two terminal columns."""
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if unicodedata.east_asian_width(char) in {"F", "W"}:
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return True
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cp = ord(char)
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return unicodedata.category(char) == "So" and (
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0x2600 <= cp <= 0x27BF or 0x1F300 <= cp <= 0x1F9FF or 0x1FA00 <= cp <= 0x1FAFF
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)
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def display_width(text: str) -> int:
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"""Calculate the display width of a string in terminal columns.
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ANSI escape codes are ignored. Wide characters (East Asian F/W and
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emoji) count as two columns, combining marks and format characters
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(e.g. emoji variation selectors) as zero.
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"""
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plain = ANSI_ESCAPE_RE.sub("", text)
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width = 0
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for char in plain:
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if unicodedata.category(char) in {"Mn", "Mc", "Me", "Cf"}:
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continue
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width += 2 if _is_wide(char) else 1
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return width
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def pad_display(text: str, width: int) -> str:
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"""Pad text with trailing spaces to the given display width (no truncation)."""
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return text + " " * max(width - display_width(text), 0)
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