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#!/usr/bin/env ruby
require_relative './grammar.rb'
class Chart
def initialize n
@m = []
(n+1).times {
_ = []
(n+1).times { _ << [] }
@m << _
}
@b = {}
end
def at i, j
@m[i][j]
end
def add item, i, j
at(i,j) << item
@b["#{i},#{j},#{item.lhs.symbol}"] = true
end
def has symbol, i, j
return @b["#{i},#{j},#{symbol}"]
end
end
class Span
attr_accessor :left, :right
def initialize left=nil, right=nil
@left = left
@right = right
end
end
class Item < Rule
attr_accessor :lhs, :rhs, :dot
def initialize rule_or_item, left, right, dot
@lhs = rule_or_item.lhs
@rhs = rule_or_item.rhs.dup
@lhs.span = Span.new left, right
@dot = dot
end
def to_s
"#{lhs} -> #{rhs.map{|i|i.to_s}.insert(@dot,'*').join ' '} [dot@#{@dot}] [arity=#{arity}] (#{@lhs.span.left}, #{@lhs.span.right})"
end
end
def init input, n, active_chart, passive_chart, grammar
grammar.flat.each { |r|
input.each_index { |i|
if input[i, r.rhs.size] == r.rhs.map { |x| x.word }
passive_chart.add Item.new(r, i, i+r.rhs.size, r.rhs.size), i, i+r.rhs.size
end
}
}
end
def scan item, input, limit, passive_chart
while item.rhs[item.dot].class == T
return false if item.lhs.span.right==limit
if item.rhs[item.dot].word == input[item.lhs.span.right]
item.dot += 1
item.lhs.span.right += 1
else
return false
end
end
return true
end
def visit i, l, r, x=0
i.upto(r-x) { |span|
l.upto(r-span) { |k|
yield k, k+span
}
}
end
def parse input, n, active_chart, passive_chart, grammar
visit(1, 0, n) { |i,j|
STDERR.write " span(#{i},#{j})\n"
# try to apply rules starting with T
grammar.startt.select { |r| r.rhs.first.word == input[i] }.each { |r|
new_item = Item.new r, i, i, 0
active_chart.at(i,j) << new_item if scan new_item, input, j, passive_chart
}
# seed active chart
grammar.startn.each { |r|
next if r.rhs.size > j-i
active_chart.at(i,j) << Item.new(r, i, i, 0)
}
# parse
new_symbols = []
remaining_items = []
while !active_chart.at(i,j).empty?
active_item = active_chart.at(i,j).pop
advanced = false
visit(1, i, j, 1) { |k,l|
if passive_chart.has active_item.rhs[active_item.dot].symbol, k, l
if k == active_item.lhs.span.right
new_item = Item.new active_item, active_item.lhs.span.left, l, active_item.dot+1
if scan new_item, input, j, passive_chart
if new_item.dot == new_item.rhs.size
if new_item.lhs.span.left == i && new_item.lhs.span.right == j
new_symbols << new_item.lhs.symbol if !new_symbols.include? new_item.lhs.symbol
passive_chart.add new_item, i, j
advanced = true
end
else
if new_item.lhs.span.right+(new_item.rhs.size-(new_item.dot)) <= j
active_chart.at(i,j) << new_item
advanced = true
end
end
end
end
end
}
if !advanced
remaining_items << active_item
end
end
# 'self-filling' step
new_symbols.each { |s|
remaining_items.each { |active_item|
next if active_item.dot!=0
next if active_item.rhs[active_item.dot].class!=NT
if active_item.rhs[active_item.dot].symbol == s
new_item = Item.new active_item, i, j, active_item.dot+1
new_symbols << new_item.lhs.symbol if !new_symbols.include? new_item.lhs.symbol
passive_chart.add new_item, i, j if new_item.dot==new_item.rhs.size
end
}
}
}
end
def main
STDERR.write "> reading input from TODO\n"
input = 'ich sah ein kleines haus'.split
#input = 'lebensmittel schuld an europäischer inflation'.split
#input = 'offizielle prognosen sind von nur 3 prozent ausgegangen , meldete bloomberg .'.split
n = input.size
STDERR.write "> reading grammar\n"
grammar = Grammar.new 'example/grammarx'
STDERR.write ">> adding glue grammar\n"
#grammar.add_glue_rules
STDERR.write ">> adding pass-through grammar\n"
#grammar.add_pass_through_rules input
STDERR.write "> initializing charts\n"
passive_chart = Chart.new n
active_chart = Chart.new n
init input, n, active_chart, passive_chart, grammar
STDERR.write "> parsing\n"
parse input, n, active_chart, passive_chart, grammar
puts "\n---\npassive chart"
visit(1, 0, 5) { |i,j| puts "#{i},#{j}"; passive_chart.at(i,j).each { |item| puts ' '+item.to_s }; puts }
end
main
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