64 lines
1.7 KiB
Ruby
64 lines
1.7 KiB
Ruby
class Imbecile
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class Parser
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def initialize(tokens, rules)
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@token_eof = Token.new("$", nil, TOKEN_EOF)
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@item_sets = []
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@item_sets_set = {}
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start_items = rules["Start"].map do |rule|
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rule.components << @token_eof
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Item.new(rule, 0)
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end
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eval_item_sets = Set.new
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eval_item_sets << ItemSet.new(start_items)
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while eval_item_sets.size > 0
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this_eval_item_sets = eval_item_sets
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eval_item_sets = Set.new
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this_eval_item_sets.each do |item_set|
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unless @item_sets_set.include?(item_set)
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item_set.id = @item_sets.size
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@item_sets << item_set
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@item_sets_set[item_set] = item_set
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item_set.follow_symbols.each do |follow_symbol|
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unless follow_symbol == @token_eof
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follow_set = item_set.build_follow_set(follow_symbol)
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eval_item_sets << follow_set
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end
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end
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end
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end
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end
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@item_sets.each do |item_set|
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process_item_set(item_set)
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puts "Item set #{item_set.id}:"
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puts item_set
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item_set.follow_item_set.each do |follow_symbol, follow_item_set|
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if follow_symbol.is_a?(Token)
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name = follow_symbol.name
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else
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name = follow_symbol[0].name
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end
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puts " #{name} => #{follow_item_set.id}"
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end
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puts
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end
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end
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private
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def process_item_set(item_set)
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item_set.follow_symbols.each do |follow_symbol|
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unless follow_symbol == @token_eof
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follow_set = @item_sets_set[item_set.build_follow_set(follow_symbol)]
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item_set.follow_item_set[follow_symbol] = follow_set
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end
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end
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end
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end
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end
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