From dc6930c00b4b276883280cff1ed6dcd9ddef03c7 Mon Sep 17 00:00:00 2001
From: Chris Dyer <redpony@gmail.com>
Date: Tue, 8 Dec 2009 21:38:55 -0500
Subject: LICENSE fixes, full support of lattice decoding

---
 src/lattice.cc | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

(limited to 'src/lattice.cc')

diff --git a/src/lattice.cc b/src/lattice.cc
index aa1df3db..56bc9551 100644
--- a/src/lattice.cc
+++ b/src/lattice.cc
@@ -5,6 +5,39 @@
 
 using namespace std;
 
+static const int kUNREACHABLE = 99999999;
+
+void Lattice::ComputeDistances() {
+  const int n = this->size() + 1;
+  dist_.resize(n, n, kUNREACHABLE);
+  for (int i = 0; i < this->size(); ++i) {
+    const vector<LatticeArc>& alts = (*this)[i];
+    for (int j = 0; j < alts.size(); ++j)
+      dist_(i, i + alts[j].dist2next) = 1;
+  }
+  for (int k = 0; k < n; ++k) {
+    for (int i = 0; i < n; ++i) {
+      for (int j = 0; j < n; ++j) {
+        const int dp = dist_(i,k) + dist_(k,j);
+        if (dist_(i,j) > dp)
+          dist_(i,j) = dp;
+      }
+    }
+  }
+
+  for (int i = 0; i < n; ++i) {
+    int latest = kUNREACHABLE;
+    for (int j = n-1; j >= 0; --j) {
+      const int c = dist_(i,j);
+      if (c < kUNREACHABLE)
+        latest = c;
+      else
+        dist_(i,j) = latest;
+    }
+  }
+  // cerr << dist_ << endl;
+}
+
 bool LatticeTools::LooksLikePLF(const string &line) {
   return (line.size() > 5) && (line.substr(0,4) == "((('");
 }
@@ -23,5 +56,6 @@ void LatticeTools::ConvertTextOrPLF(const string& text_or_plf, Lattice* pl) {
     HypergraphIO::PLFtoLattice(text_or_plf, pl);
   else
     ConvertTextToLattice(text_or_plf, pl);
+  pl->ComputeDistances();
 }
 
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