70 lines
1.3 KiB
Ruby
70 lines
1.3 KiB
Ruby
class Imbecile
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class Parser
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class Item
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attr_reader :pattern
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attr_reader :position
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def initialize(pattern, position)
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@pattern = pattern
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@position = position
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end
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def next_component
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@pattern.components[@position]
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end
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def hash
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[@pattern, @position].hash
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end
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def ==(other)
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@pattern == other.pattern && @position == other.position
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end
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def eql?(other)
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self == other
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end
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def closed_items
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if @pattern.components[@position].is_a?(Rule)
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@pattern.components[@position].patterns.map do |pattern|
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Item.new(pattern, 0)
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end
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else
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[]
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end
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end
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def follow_symbol
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@pattern.components[@position]
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end
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def followed_by?(symbol)
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follow_symbol == symbol
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end
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def next_position
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Item.new(@pattern, @position + 1)
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end
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def to_s
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parts = []
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@pattern.components.each_with_index do |symbol, index|
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if @position == index
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parts << "."
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end
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parts << symbol.name
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end
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if @position == @pattern.components.size
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parts << "."
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end
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parts.join(" ")
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end
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end
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end
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end
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