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/state.hh | 123 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 123 insertions(+)
 create mode 100644 klm/lm/state.hh

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

diff --git a/klm/lm/state.hh b/klm/lm/state.hh
new file mode 100644
index 00000000..c7438414
--- /dev/null
+++ b/klm/lm/state.hh
@@ -0,0 +1,123 @@
+#ifndef LM_STATE__
+#define LM_STATE__
+
+#include "lm/max_order.hh"
+#include "lm/word_index.hh"
+#include "util/murmur_hash.hh"
+
+#include <string.h>
+
+namespace lm {
+namespace ngram {
+
+// This is a POD but if you want memcmp to return the same as operator==, call
+// ZeroRemaining first.    
+class State {
+  public:
+    bool operator==(const State &other) const {
+      if (length != other.length) return false;
+      return !memcmp(words, other.words, length * sizeof(WordIndex));
+    }
+
+    // Three way comparison function.  
+    int Compare(const State &other) const {
+      if (length != other.length) return length < other.length ? -1 : 1;
+      return memcmp(words, other.words, length * sizeof(WordIndex));
+    }
+
+    bool operator<(const State &other) const {
+      if (length != other.length) return length < other.length;
+      return memcmp(words, other.words, length * sizeof(WordIndex)) < 0;
+    }
+
+    // Call this before using raw memcmp.  
+    void ZeroRemaining() {
+      for (unsigned char i = length; i < kMaxOrder - 1; ++i) {
+        words[i] = 0;
+        backoff[i] = 0.0;
+      }
+    }
+
+    unsigned char Length() const { return length; }
+
+    // You shouldn't need to touch anything below this line, but the members are public so FullState will qualify as a POD.  
+    // This order minimizes total size of the struct if WordIndex is 64 bit, float is 32 bit, and alignment of 64 bit integers is 64 bit.  
+    WordIndex words[kMaxOrder - 1];
+    float backoff[kMaxOrder - 1];
+    unsigned char length;
+};
+
+inline uint64_t hash_value(const State &state, uint64_t seed = 0) {
+  return util::MurmurHashNative(state.words, sizeof(WordIndex) * state.length, seed);
+}
+
+struct Left {
+  bool operator==(const Left &other) const {
+    return 
+      (length == other.length) && 
+      pointers[length - 1] == other.pointers[length - 1] &&
+      full == other.full;
+  }
+
+  int Compare(const Left &other) const {
+    if (length < other.length) return -1;
+    if (length > other.length) return 1;
+    if (pointers[length - 1] > other.pointers[length - 1]) return 1;
+    if (pointers[length - 1] < other.pointers[length - 1]) return -1;
+    return (int)full - (int)other.full;
+  }
+
+  bool operator<(const Left &other) const {
+    return Compare(other) == -1;
+  }
+
+  void ZeroRemaining() {
+    for (uint64_t * i = pointers + length; i < pointers + kMaxOrder - 1; ++i)
+      *i = 0;
+  }
+
+  uint64_t pointers[kMaxOrder - 1];
+  unsigned char length;
+  bool full;
+};
+
+inline uint64_t hash_value(const Left &left) {
+  unsigned char add[2];
+  add[0] = left.length;
+  add[1] = left.full;
+  return util::MurmurHashNative(add, 2, left.length ? left.pointers[left.length - 1] : 0);
+}
+
+struct ChartState {
+  bool operator==(const ChartState &other) {
+    return (right == other.right) && (left == other.left);
+  }
+
+  int Compare(const ChartState &other) const {
+    int lres = left.Compare(other.left);
+    if (lres) return lres;
+    return right.Compare(other.right);
+  }
+
+  bool operator<(const ChartState &other) const {
+    return Compare(other) == -1;
+  }
+
+  void ZeroRemaining() {
+    left.ZeroRemaining();
+    right.ZeroRemaining();
+  }
+
+  Left left;
+  State right;
+};
+
+inline uint64_t hash_value(const ChartState &state) {
+  return hash_value(state.right, hash_value(state.left));
+}
+
+
+} // namespace ngram
+} // namespace lm
+
+#endif // LM_STATE__
-- 
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