42 lines
1.1 KiB
Ruby
42 lines
1.1 KiB
Ruby
# -*- coding: utf-8; frozen_string_literal: true -*-
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#
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#--
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# Copyright (C) 2009-2026 Thomas Leitner <t_leitner@gmx.at>
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#
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# This file is part of kramdown which is licensed under the MIT.
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#++
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#
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module Kramdown
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module Utils
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# A simple least recently used (LRU) cache.
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#
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# The cache relies on the fact that Ruby's Hash class maintains insertion order. So deleting
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# and re-inserting a key-value pair on access moves the key to the last position. When an
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# entry is added and the cache is full, the first entry is removed.
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class LRUCache
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# Creates a new LRUCache that can hold +size+ entries.
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def initialize(size)
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@size = size
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@cache = {}
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end
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# Returns the stored value for +key+ or +nil+ if no value was stored under the key.
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def [](key)
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(val = @cache.delete(key)).nil? ? nil : @cache[key] = val
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end
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# Stores the +value+ under the +key+.
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def []=(key, value)
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@cache.delete(key)
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@cache[key] = value
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@cache.shift if @cache.length > @size
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end
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end
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end
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end
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