From 149232c38eec558ddb1097698d1570aacb67b59f Mon Sep 17 00:00:00 2001
From: Kenneth Heafield <github@kheafield.com>
Date: Wed, 16 May 2012 13:24:08 -0700
Subject: Big kenlm change includes lower order models for probing only.  And
 other stuff.

---
 klm/lm/value_build.hh | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 klm/lm/value_build.hh

(limited to 'klm/lm/value_build.hh')

diff --git a/klm/lm/value_build.hh b/klm/lm/value_build.hh
new file mode 100644
index 00000000..687a41a0
--- /dev/null
+++ b/klm/lm/value_build.hh
@@ -0,0 +1,97 @@
+#ifndef LM_VALUE_BUILD__
+#define LM_VALUE_BUILD__
+
+#include "lm/weights.hh"
+#include "lm/word_index.hh"
+#include "util/bit_packing.hh"
+
+#include <vector>
+
+namespace lm {
+namespace ngram {
+
+class Config;
+class BackoffValue;
+class RestValue;
+
+class NoRestBuild {
+  public:
+    typedef BackoffValue Value;
+
+    NoRestBuild() {}
+
+    void SetRest(const WordIndex *, unsigned int, const Prob &/*prob*/) const {}
+    void SetRest(const WordIndex *, unsigned int, const ProbBackoff &) const {}
+
+    template <class Second> bool MarkExtends(ProbBackoff &weights, const Second &) const {
+      util::UnsetSign(weights.prob);
+      return false;
+    }
+
+    // Probing doesn't need to go back to unigram.
+    const static bool kMarkEvenLower = false;
+};
+
+class MaxRestBuild {
+  public:
+    typedef RestValue Value;
+
+    MaxRestBuild() {}
+
+    void SetRest(const WordIndex *, unsigned int, const Prob &/*prob*/) const {}
+    void SetRest(const WordIndex *, unsigned int, RestWeights &weights) const {
+      weights.rest = weights.prob;
+      util::SetSign(weights.rest);
+    }
+
+    bool MarkExtends(RestWeights &weights, const RestWeights &to) const {
+      util::UnsetSign(weights.prob);
+      if (weights.rest >= to.rest) return false;
+      weights.rest = to.rest;
+      return true;
+    }
+    bool MarkExtends(RestWeights &weights, const Prob &to) const {
+      util::UnsetSign(weights.prob);
+      if (weights.rest >= to.prob) return false;
+      weights.rest = to.prob;
+      return true;
+    }
+
+    // Probing does need to go back to unigram.  
+    const static bool kMarkEvenLower = true;
+};
+
+template <class Model> class LowerRestBuild {
+  public:
+    typedef RestValue Value;
+
+    LowerRestBuild(const Config &config, unsigned int order, const typename Model::Vocabulary &vocab);
+
+    ~LowerRestBuild();
+
+    void SetRest(const WordIndex *, unsigned int, const Prob &/*prob*/) const {}
+    void SetRest(const WordIndex *vocab_ids, unsigned int n, RestWeights &weights) const {
+      typename Model::State ignored;
+      if (n == 1) {
+        weights.rest = unigrams_[*vocab_ids];
+      } else {
+        weights.rest = models_[n-2]->FullScoreForgotState(vocab_ids + 1, vocab_ids + n, *vocab_ids, ignored).prob;
+      }
+    }
+
+    template <class Second> bool MarkExtends(RestWeights &weights, const Second &) const {
+      util::UnsetSign(weights.prob);
+      return false;
+    }
+
+    const static bool kMarkEvenLower = false;
+
+    std::vector<float> unigrams_;
+
+    std::vector<const Model*> models_;
+};
+
+} // namespace ngram
+} // namespace lm
+
+#endif // LM_VALUE_BUILD__
-- 
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