Yunxiao Xu
93c777cf6a
Thread RP_DEBUG-driven logging through input, detection, rendering, and pager decisions so CLI behavior is inspectable without polluting stdout. Add focused coverage for debug wiring, env parsing, and stderr-only output.
102 lines
3.4 KiB
Python
102 lines
3.4 KiB
Python
"""Less-based pager integration with mouse support and fallback."""
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from __future__ import annotations
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import re
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import signal
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import shutil
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import subprocess
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from rich.pager import Pager, SystemPager
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from rp.debug import DebugLogger, log_debug
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def _mouse_capable_less(debug: DebugLogger | None = None) -> str | None:
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"""Return a ``less`` path that likely supports ``--mouse``.
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Mouse support was added in ``less`` 543. This probe is best-effort: it
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checks that ``less`` exists, asks for its version string, and extracts the
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version number from the leading ``less <version>`` banner. Any unexpected
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output is treated as unsupported so the caller can fall back safely.
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Returns:
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The resolved ``less`` executable path when it appears mouse-capable,
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otherwise ``None``.
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"""
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less = shutil.which("less")
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if less is None:
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log_debug(debug, "pager: 'less' was not found")
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return None
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try:
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result = subprocess.run(
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[less, "--version"], capture_output=True, text=True, timeout=5
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)
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except (subprocess.TimeoutExpired, OSError):
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log_debug(debug, "pager: failed to probe the installed 'less' binary")
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return None
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version_str = result.stdout or result.stderr or ""
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match = re.search(r"\bless\s+(\d+)\b", version_str, re.IGNORECASE)
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if match is None:
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log_debug(debug, "pager: could not parse the installed 'less' version")
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return None
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version = int(match.group(1))
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if version < 543:
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log_debug(debug, f"pager: installed 'less' {version} is too old for --mouse")
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return None
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log_debug(debug, f"pager: using 'less' {version} from {less!r}")
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return less
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class MousePager(Pager):
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"""Pager that prefers ``less -R --mouse`` for mouse scrolling.
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``less`` is the prerequisite for mouse-enabled paging in this project. If
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``less`` is missing, too old, cannot be launched, or exits with a non-zero
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status, we fall back to Rich's ``SystemPager``. A user interrupt does not
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trigger a second pager session.
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"""
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def __init__(self, debug: DebugLogger | None = None) -> None:
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"""Initialize the pager with an optional debug logger."""
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self._debug = debug
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def show(self, content: str) -> None:
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"""Display rendered content in ``less -R --mouse`` when possible.
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Args:
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content: Fully rendered text from Rich.
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"""
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less = _mouse_capable_less(self._debug)
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if less is None:
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log_debug(self._debug, "pager: falling back to Rich's SystemPager")
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SystemPager().show(content)
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return
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try:
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log_debug(self._debug, "pager: launching 'less -R --mouse'")
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result = subprocess.run(
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[less, "-R", "--mouse"],
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input=content,
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text=True,
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)
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except OSError:
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log_debug(self._debug, "pager: failed to launch 'less', using SystemPager")
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SystemPager().show(content)
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return
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if result.returncode in (-signal.SIGINT, 128 + signal.SIGINT):
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log_debug(self._debug, "pager: interrupted by user")
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return
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if result.returncode != 0:
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log_debug(
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self._debug,
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f"pager: 'less' exited with status {result.returncode}, using SystemPager",
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)
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SystemPager().show(content)
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