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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 << _
}
end
def at i, j
@m[i][j]
end
def add r, i, j, right, dot=0
item = Item.new(r)
item.span.left = i
item.span.right = right
item.dot = dot
at(i, j) << item
end
end
class Item < Rule
attr_accessor :lhs, :rhs, :span, :dot
def initialize rule
@lhs = rule.lhs.dup
@rhs = rule.rhs.dup
@span = Span.new rule.span.left, rule.span.right
@dot = rule.dot if rule.class==Item
end
def to_s
"#{lhs} -> #{rhs.map{|i|i.to_s}.insert(@dot,'*').join ' '} [dot@#{@dot}] [arity=#{arity}] (#{@span.left}, #{@span.right})"
end
end
def visit n, depth, skip=0
(depth-skip).times { |i|
i += skip
0.upto(n-(i+1)) { |j|
yield j, j+i+1 if block_given?
}
}
end
def init active_chart, passive_chart, grammar, input, n
# pre-fill passive chart w/ 0-arity rules
grammar.rules.select { |r| r.rhs.first.class==Terminal }.each { |r|
input.each_index.select { |i| input[i].w==r.rhs.first.w }.each { |j|
k = 1
if r.rhs.size > 1
z = r.rhs.index { |i| i.class==NonTerminal }
if z
z -= 1
else
z = r.rhs.size-1
end
if input[j..j+z].map { |i| i.w } == r.rhs[0..z].map { |i| i.w }
k = z+1
else
next
end
end
if k == r.rhs.size
passive_chart.add(r, j, j+k, j+k, k)
else
(j+k).upto(n) { |l| active_chart.add(r, j, l, j+k, k) }
end
}
}
# seed active chart
s = grammar.rules.reject { |r| r.rhs.first.class!=NonTerminal }
visit(n, n, 1) { |i,j|
s.each { |r| active_chart.add(r, i, j, i) }
}
end
def scan item, passive_chart, input, i, j
while item.rhs[item.dot].class == Terminal
if item.rhs[item.dot].w == input[item.span.left+item.dot].w
item.dot += 1
item.span.right = item.span.left+item.dot
if item.dot == item.rhs.size
passive_chart.add(item, i, j, item.span.left+item.dot, item.dot)
break
end
end
end
end
def parse i, j, sz, active_chart, passive_chart, g, input
1.upto(sz) { |span|
break if span==(j-i)
i.upto(j-span) { |k|
active_chart.at(i,j).each { |active_item|
passive_chart.at(k, k+span).each { |passive_item|
if active_item.rhs[active_item.dot].class==NonTerminal && passive_item.lhs.sym == active_item.rhs[active_item.dot].sym
next if not active_item.span.right==passive_item.span.left
active_item.span.right = passive_item.span.right
active_item.dot += 1
scan active_item, passive_chart, input, i, j
passive_chart.at(i,j) << Item.new(active_item) if active_item.dot==active_item.rhs.size
end
}
}
}
}
end
def main
g = Grammar.new 'grammar'
input = "ich sah ein kleines haus".split.map { |i| Terminal.new i }
n = input.size
passive_chart = Chart.new n
active_chart = Chart.new n
init active_chart, passive_chart, g, input, n
visit(n, n, 1) { |i,j| parse i, j, n, active_chart, passive_chart, g, input }
visit(n, n, 0) { |i,j| puts "#{i},#{j}"; passive_chart.at(i,j).each { |item| puts item.to_s } }
end
main
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