From d70b8ff2917c027268e9bc1178b4e035164a5ca8 Mon Sep 17 00:00:00 2001
From: Keisuke Kuroyanagi <ksk@google.com>
Date: Mon, 13 Oct 2014 16:07:29 +0900
Subject: [PATCH] Fix: BoS bigram from user history dictionary is too strong.

They can be always stronger than BoS predictions from the
contextual dictionary.

Bug: 17961731
Change-Id: I70297d82436c10c790bdfad6f3dfefdb4bb2f852
---
 .../backward/v402/ver4_patricia_trie_policy.cpp      | 12 +++++++++---
 .../backward/v402/ver4_patricia_trie_policy.h        |  2 +-
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.cpp
index 1c61bd4b9..0eae934ae 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.cpp
@@ -186,7 +186,9 @@ int Ver4PatriciaTriePolicy::getProbabilityOfWord(const WordIdArrayView prevWordI
         if (bigramsIt.getBigramPos() == ptNodePos
                 && bigramsIt.getProbability() != NOT_A_PROBABILITY) {
             const int bigramConditionalProbability = getBigramConditionalProbability(
-                    prevWordPtNodeParams.getProbability(), bigramsIt.getProbability());
+                    prevWordPtNodeParams.getProbability(),
+                    prevWordPtNodeParams.representsBeginningOfSentence(),
+                    bigramsIt.getProbability());
             return getProbability(ptNodeParams.getProbability(), bigramConditionalProbability);
         }
     }
@@ -209,15 +211,19 @@ void Ver4PatriciaTriePolicy::iterateNgramEntries(const WordIdArrayView prevWordI
     while (bigramsIt.hasNext()) {
         bigramsIt.next();
         const int bigramConditionalProbability = getBigramConditionalProbability(
-                prevWordPtNodeParams.getProbability(), bigramsIt.getProbability());
+                prevWordPtNodeParams.getProbability(),
+                prevWordPtNodeParams.representsBeginningOfSentence(), bigramsIt.getProbability());
         listener->onVisitEntry(bigramConditionalProbability,
                 getWordIdFromTerminalPtNodePos(bigramsIt.getBigramPos()));
     }
 }
 
 int Ver4PatriciaTriePolicy::getBigramConditionalProbability(const int prevWordUnigramProbability,
-        const int bigramProbability) const {
+        const bool isInBeginningOfSentenceContext, const int bigramProbability) const {
     if (mHeaderPolicy->hasHistoricalInfoOfWords()) {
+        if (isInBeginningOfSentenceContext) {
+            return bigramProbability;
+        }
         // Calculate conditional probability.
         return std::min(MAX_PROBABILITY - prevWordUnigramProbability + bigramProbability,
                 MAX_PROBABILITY);
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.h
index 4aa399c3e..1ad5e7e36 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/backward/v402/ver4_patricia_trie_policy.h
@@ -175,7 +175,7 @@ class Ver4PatriciaTriePolicy : public DictionaryStructureWithBufferPolicy {
     const WordAttributes getWordAttributes(const int probability,
             const PtNodeParams &ptNodeParams) const;
     int getBigramConditionalProbability(const int prevWordUnigramProbability,
-            const int bigramProbability) const;
+            const bool isInBeginningOfSentenceContext, const int bigramProbability) const;
 };
 } // namespace v402
 } // namespace backward