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91 lines
2.5 KiB
Python
91 lines
2.5 KiB
Python
"""Adds head/tail functionality to list/ls.
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1. Implemented as `lslimit` command with `--head` and `--tail` options. This is
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the idiomatic way to use this plugin.
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2. Implemented as query prefix `<` for head functionality only. This is the
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composable way to use the plugin (plays nicely with anything that uses the
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query language).
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"""
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from __future__ import annotations
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from collections import deque
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from itertools import islice
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from typing import TYPE_CHECKING
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from beets.dbcore import FieldQuery
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from beets.plugins import BeetsPlugin
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from beets.ui import Subcommand, print_
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if TYPE_CHECKING:
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import optparse
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from beets.library import Library
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def lslimit(lib: Library, opts: optparse.Values, args: list[str]) -> None:
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"""Query command with head/tail."""
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if (opts.head is not None) and (opts.tail is not None):
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raise ValueError("Only use one of --head and --tail")
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if (opts.head or opts.tail or 0) < 0:
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raise ValueError("Limit value must be non-negative")
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if opts.album:
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objs = lib.albums(args)
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else:
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objs = lib.items(args)
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if opts.head is not None:
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objs = islice(objs, opts.head)
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elif opts.tail is not None:
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objs = deque(objs, opts.tail)
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for obj in objs:
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print_(format(obj))
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lslimit_cmd = Subcommand("lslimit", help="query with optional head or tail")
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lslimit_cmd.parser.add_option(
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"--head", action="store", type="int", default=None
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)
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lslimit_cmd.parser.add_option(
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"--tail", action="store", type="int", default=None
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)
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lslimit_cmd.parser.add_all_common_options()
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lslimit_cmd.func = lslimit
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class LimitPlugin(BeetsPlugin):
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"""Query limit functionality via command and query prefix."""
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def commands(self):
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"""Expose `lslimit` subcommand."""
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return [lslimit_cmd]
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def queries(self):
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class HeadQuery(FieldQuery):
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"""This inner class pattern allows the query to track state."""
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n = 0
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N = None
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def __init__(self, *args, **kwargs) -> None:
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"""Force the query to be slow so that 'value_match' is called."""
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super().__init__(*args, **kwargs)
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self.fast = False
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@classmethod
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def value_match(cls, pattern, value):
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if cls.N is None:
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cls.N = int(pattern)
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if cls.N < 0:
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raise ValueError("Limit value must be non-negative")
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cls.n += 1
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return cls.n <= cls.N
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return {"<": HeadQuery}
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