From 77666a09c0f82b231605da463a946a5a5fcd09b6 Mon Sep 17 00:00:00 2001
From: Patrick Simianer <patrick@lilt.com>
Date: Tue, 24 Feb 2026 17:07:57 +0100
Subject: Fix reordering bug in derive and add test example

derive used a sequential counter to index into the source-side NT map,
which only worked for monotone rules. Now looks up tails by the target
NT's own index via map.index(i.index).

Adds toy-reorder example (German verb-final -> English SVO) to exercise
the fix. Also updates trollop -> optimist and guards xmlsimple require.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 example/toy-reorder/grammar     | 6 ++++++
 example/toy-reorder/in          | 1 +
 example/toy-reorder/weights.toy | 1 +
 prototype/hypergraph.rb         | 4 +---
 prototype/ow_proto.rb           | 6 +++---
 5 files changed, 12 insertions(+), 6 deletions(-)
 create mode 100644 example/toy-reorder/grammar
 create mode 100644 example/toy-reorder/in
 create mode 100644 example/toy-reorder/weights.toy

diff --git a/example/toy-reorder/grammar b/example/toy-reorder/grammar
new file mode 100644
index 0000000..d93d98c
--- /dev/null
+++ b/example/toy-reorder/grammar
@@ -0,0 +1,6 @@
+[S] ||| [NP,1] [VP,2] ||| [NP,1] [VP,2] ||| logp=0
+[NP] ||| er ||| he ||| logp=-0.5
+[NP] ||| das [NN,1] ||| the [NN,1] ||| logp=0
+[NN] ||| buch ||| book ||| logp=0
+[VP] ||| [NP,1] [V,2] ||| [V,2] [NP,1] ||| logp=0
+[V] ||| liest ||| reads ||| logp=-0.25
diff --git a/example/toy-reorder/in b/example/toy-reorder/in
new file mode 100644
index 0000000..6eeb3a9
--- /dev/null
+++ b/example/toy-reorder/in
@@ -0,0 +1 @@
+er das buch liest
diff --git a/example/toy-reorder/weights.toy b/example/toy-reorder/weights.toy
new file mode 100644
index 0000000..3eb2502
--- /dev/null
+++ b/example/toy-reorder/weights.toy
@@ -0,0 +1 @@
+logp 2
diff --git a/prototype/hypergraph.rb b/prototype/hypergraph.rb
index fd72393..fdaba5a 100644
--- a/prototype/hypergraph.rb
+++ b/prototype/hypergraph.rb
@@ -196,11 +196,9 @@ def HG::derive path, cur, carry
   edge = path.select { |e|    e.head.symbol==cur.symbol \
                            && e.head.left==cur.left \
                            && e.head.right==cur.right }.first
-  j = 0
   edge.rule.target.each { |i|
     if i.class == Grammar::NT
-      derive path, edge.tails[edge.rule.map[j]], carry
-      j += 1
+      derive path, edge.tails[edge.rule.map.index(i.index)], carry
     else
       carry << i
     end
diff --git a/prototype/ow_proto.rb b/prototype/ow_proto.rb
index 912090b..41fe683 100755
--- a/prototype/ow_proto.rb
+++ b/prototype/ow_proto.rb
@@ -1,7 +1,7 @@
 #!/usr/bin/env ruby
 
-require 'trollop'
-require 'xmlsimple'
+require 'optimist'
+begin; require 'xmlsimple'; rescue LoadError; end
 require_relative 'parse'
 
 def read_grammar fn, add_glue, add_pass_through, input=nil
@@ -19,7 +19,7 @@ def read_grammar fn, add_glue, add_pass_through, input=nil
 end
 
 def main
-  cfg = Trollop::options do
+  cfg = Optimist::options do
     opt :input,            "", :type => :string, :default => '-',    :short => '-i'
     opt :grammar,          "", :type => :string, :required => true,  :short => '-g'
     opt :weights,          "", :type => :string, :required => true,  :short => '-w'
-- 
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