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|
#!/usr/bin/env ruby
require_relative './grammar.rb'
class Chart
def initialize input
@m = []
(input.size+1).times {
_ = []
(input.size+1).times { _ << [] }
@m << _
}
end
def at i,j
return @m[i][j]
end
end
class Item < Rule
attr_accessor :lhs, :rhs, :span, :dot
def initialize rule, dot=-1
@lhs = rule.lhs.dup
@rhs = rule.rhs.dup
@span = Span.new rule.span.left, rule.span.right
@dot = dot
if rule.class==Item
@dot = rule.dot
end
end
def to_s
"#{lhs} -> #{rhs.map{|i|i.to_s}.insert(@dot,'*').join ' '} dot:#{@dot} a:#{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
# set-up
g = Grammar.new 'grammar'
input = "ich sah ein kleines haus".split.map { |i| Terminal.new i }
n = input.size
passive_chart = Chart.new input
active_chart = Chart.new input
# pre-fill passive chart w/ 0-arity rules
g.rules.select { |r| r.rhs.first.class==Terminal }.each { |r|
input.each_index.select{ |j| input[j].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
slice = input[j..j+z].map { |i| i.w }
if slice == r.rhs[0..z].map { |i| i.w }
k = z+1
else
next
end
end
if k == r.rhs.size
passive_chart.at(j,j+k) << Item.new(r)
passive_chart.at(j,j+k).last.span.left = j
passive_chart.at(j,j+k).last.span.right = j+k
passive_chart.at(j,j+k).last.dot = k
else
(j+k).upto(input.size) { |l|
active_chart.at(j,l) << Item.new(r)
active_chart.at(j,l).last.span.left = j
active_chart.at(j,l).last.span.right = j+k
active_chart.at(j,l).last.dot = k
}
end
}
}
# seed active chart
s = g.rules.reject { |r| r.rhs.first.class!=NonTerminal }
visit(n, n, 1) { |i,j|
s.each { |r|
active_chart.at(i,j) << Item.new(r)
active_chart.at(i,j).last.span.left = i
active_chart.at(i,j).last.span.right = i
active_chart.at(i,j).last.dot = 0
}
}
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 += 1
if item.dot == item.rhs.size
passive_chart.at(i,j) << Item.new(item)
passive_chart.at(i,j).last.span.right = item.span.left+item.dot
end
end
end
end
# parse
def parse i, j, sz, active_chart, passive_chart, g, input
puts "| #{i},#{j}"
1.upto(sz) { |span|
break if span==(j-i)
i.upto(j-span) { |k|
puts " #{k},#{k+span} (##{span})"
# complete
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
if active_item.dot == active_item.rhs.size
passive_chart.at(i,j) << Item.new(active_item)
end
end
}
}
}
}
end
visit(n, n, 1) { |i,j|
parse i, j, n, active_chart, passive_chart, g, input
}
puts "---"
passive_chart.at(0,5).each { |item|
puts item.to_s
}
|
