1 files changed, 174 insertions, 0 deletions
diff --git a/intersect.rb b/intersect.rb
new file mode 100644
index 0000000..8a583da
--- /dev/null
+++ b/intersect.rb
@@ -0,0 +1,174 @@
+#!/usr/bin/env ruby
+
+require_relative './grammar.rb'
+
+# interescts a WFSA (WFST) with a WSCFG to produce a hypergraph
+
+
+
+class Chart
+  attr_accessor :m
+  
+  def initialize input
+    @m = []
+    (input.size+1).times {
+      _ = []
+      (input.size+1).times { _ << [] }
+      @m << _
+    }
+  end
+
+  def at span
+    return @m[span.left][span.right]
+  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 shift
+#end
+#def reduce
+#end
+#def init
+  #axioms,goals etc
+#end
+#def parse
+#end
+
+
+g = Grammar.new 'grammar'
+input = "ich sah ein kleines haus".split.map { |i| Terminal.new i }
+#start =  NonTerminal.new 'S'
+
+passive_chart = Chart.new input
+active_chart = Chart.new input
+
+
+
+# 1st row: arity0 rules
+unary_rules = g.rules.reject { |r| r.arity>0 }
+input.each_with_index { |t,j|
+  unary_rules.each { |r|
+    if r.rhs.first.w == t.w
+      passive_chart.at(j,j+1) << Item.new(r)
+      passive_chart.at(j,j+1).last.span.left = j
+      passive_chart.at(j,j+1).last.span.right = j+1
+      passive_chart.at(j,j+1).last.dot = 1
+    end
+  }
+}
+
+
+
+# pre-fill active chart with non 0arity rules starting with a (single(!)) T
+g.rules.reject{|r| r.rhs[0].class==NonTerminal||r.arity==0}.each {|r|
+  input.each_with_index { |i,j|
+    if i.w==r.rhs.first.w
+      (j+2).upto(input.size) { |k| # no empty NT!
+        active_chart.at(j,k) << Item.new(r)
+        active_chart.at(j,k).last.span.left = j
+        active_chart.at(j,k).last.span.right = k #j+1 # k
+        active_chart.at(j,k).last.dot = 1
+      }
+    end
+  }
+}
+# pre-fill active chart
+s = g.rules.reject { |r| r.rhs.first.class!=NonTerminal}#.reject{|r| r.lhs.sym == 'S'}
+(input.size).times { |k|
+  0.upto(input.size-(k+2)) { |i|
+    s.each { |r|
+    active_chart.at(i,i+k+2) << Item.new(r)
+    active_chart.at(i,i+k+2).last.span.left = i
+    active_chart.at(i,i+k+2).last.span.right = i+k+2
+    active_chart.at(i,i+k+2).last.dot = 0
+    }
+  }
+}
+
+
+
+# parse
+puts "parse"
+def visit i, j, sz, active_chart, passive_chart, g, input
+  puts "| #{i},#{j}"
+
+  # SCAN
+  active_chart.at(i,j).each { |item|
+    if item.rhs[item.dot].class == Terminal
+      if item.rhs[item.dot].w == input[item.span.left+item.dot].w
+        item.dot += 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
+  }
+
+  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
+          active_item.span.right = passive_item.span.right if passive_item.span.right > active_item.span.right
+          active_item.dot += 1
+          if active_item.dot == active_item.rhs.size
+            passive_chart.at(i,j) << Item.new(active_item)
+          end
+        end
+      }
+      }
+    }
+
+  # SCAN
+  active_chart.at(i,j).each { |item|
+    if item.rhs[item.dot].class == Terminal
+      if item.rhs[item.dot].w == input[item.span.left+item.dot].w
+        item.dot += 1
+        if item.dot == item.rhs.size
+          passive_chart.at(i,j) << Item.new(item)
+        end
+      end
+    end
+  }
+
+  }
+end
+
+(input.size).times { |k|
+  0.upto(input.size-(k+2)) { |i|
+    visit i, i+k+2, input.size, active_chart, passive_chart, g, input 
+  }
+}
+puts "---"
+
+active_chart.at(0,5).each { |item|
+  puts item.to_s
+}
+