Make PrevWordsInfo have multiple words' information.

Bug: 14425059
Change-Id: I2bd6a872904a44b80f638a13d91a97559217cc1a

1 files changed, 97 insertions, 22 deletions

diff --git a/java/src/com/android/inputmethod/latin/PrevWordsInfo.java b/java/src/com/android/inputmethod/latin/PrevWordsInfo.java
index 42b311c69..5dda44445 100644
--- a/java/src/com/android/inputmethod/latin/PrevWordsInfo.java
+++ b/java/src/com/android/inputmethod/latin/PrevWordsInfo.java
@@ -16,47 +16,122 @@
 
 package com.android.inputmethod.latin;
 
+import java.util.Arrays;
+
+import com.android.inputmethod.latin.utils.StringUtils;
+
 /**
  * Class to represent information of previous words. This class is used to add n-gram entries
  * into binary dictionaries, to get predictions, and to get suggestions.
  */
-// TODO: Support multiple previous words for n-gram.
 public class PrevWordsInfo {
-    public static final PrevWordsInfo EMPTY_PREV_WORDS_INFO = new PrevWordsInfo(null);
+    public static final PrevWordsInfo EMPTY_PREV_WORDS_INFO =
+            new PrevWordsInfo(WordInfo.EMPTY_WORD_INFO);
     public static final PrevWordsInfo BEGINNING_OF_SENTENCE = new PrevWordsInfo();
 
-    // The word immediately before the considered word. null means we don't have any context
-    // including the "beginning of sentence context" - we just don't know what to predict.
-    // An example of that is after a comma.
-    // For simplicity of implementation, this may also be null transiently after the WordComposer
-    // was reset and before starting a new composing word, but we should never be calling
-    // getSuggetions* in this situation.
-    // This is an empty string when mIsBeginningOfSentence is true.
-    public final String mPrevWord;
+    /**
+     * Word information used to represent previous words information.
+     */
+    public static class WordInfo {
+        public static final WordInfo EMPTY_WORD_INFO = new WordInfo(null);
+        public static final WordInfo BEGINNING_OF_SENTENCE = new WordInfo();
+
+        // This is an empty string when mIsBeginningOfSentence is true.
+        public final String mWord;
+        // TODO: Have sentence separator.
+        // Whether the current context is beginning of sentence or not. This is true when composing
+        // at the beginning of an input field or composing a word after a sentence separator.
+        public final boolean mIsBeginningOfSentence;
+
+        // Beginning of sentence.
+        public WordInfo() {
+            mWord = "";
+            mIsBeginningOfSentence = true;
+        }
+
+        public WordInfo(final String word) {
+            mWord = word;
+            mIsBeginningOfSentence = false;
+        }
+
+        public boolean isValid() {
+            return mWord != null;
+        }
+    }
 
-    // TODO: Have sentence separator.
-    // Whether the current context is beginning of sentence or not. This is true when composing at
-    // the beginning of an input field or composing a word after a sentence separator.
-    public final boolean mIsBeginningOfSentence;
+    // The words immediately before the considered word. EMPTY_WORD_INFO element means we don't
+    // have any context for that previous word including the "beginning of sentence context" - we
+    // just don't know what to predict using the information. An example of that is after a comma.
+    // For simplicity of implementation, elements may also be EMPTY_WORD_INFO transiently after the
+    // WordComposer was reset and before starting a new composing word, but we should never be
+    // calling getSuggetions* in this situation.
+    public WordInfo[] mPrevWordsInfo = new WordInfo[Constants.MAX_PREV_WORD_COUNT_FOR_N_GRAM];
 
     // Beginning of sentence.
     public PrevWordsInfo() {
-        mPrevWord = "";
-        mIsBeginningOfSentence = true;
+        mPrevWordsInfo[0] = WordInfo.BEGINNING_OF_SENTENCE;
+        Arrays.fill(mPrevWordsInfo, 1 /* start */, mPrevWordsInfo.length, WordInfo.EMPTY_WORD_INFO);
     }
 
-    public PrevWordsInfo(final String prevWord) {
-        mPrevWord = prevWord;
-        mIsBeginningOfSentence = false;
+    // Construct from the previous word information.
+    public PrevWordsInfo(final WordInfo prevWordInfo) {
+        mPrevWordsInfo[0] = prevWordInfo;
+        Arrays.fill(mPrevWordsInfo, 1 /* start */, mPrevWordsInfo.length, WordInfo.EMPTY_WORD_INFO);
+    }
+
+    // Construct from WordInfo array. n-th element represents (n+1)-th previous word's information.
+    public PrevWordsInfo(final WordInfo[] prevWordsInfo) {
+        for (int i = 0; i < Constants.MAX_PREV_WORD_COUNT_FOR_N_GRAM; i++) {
+            mPrevWordsInfo[i] =
+                    (prevWordsInfo.length > i) ? prevWordsInfo[i] : WordInfo.EMPTY_WORD_INFO;
+        }
+    }
+
+    // Create next prevWordsInfo using current prevWordsInfo.
+    public PrevWordsInfo getNextPrevWordsInfo(final WordInfo wordInfo) {
+        final WordInfo[] prevWordsInfo = new WordInfo[Constants.MAX_PREV_WORD_COUNT_FOR_N_GRAM];
+        prevWordsInfo[0] = wordInfo;
+        for (int i = 1; i < prevWordsInfo.length; i++) {
+            prevWordsInfo[i] = mPrevWordsInfo[i - 1];
+        }
+        return new PrevWordsInfo(prevWordsInfo);
     }
 
     public boolean isValid() {
-        return mPrevWord != null;
+        return mPrevWordsInfo[0].isValid();
+    }
+
+    public void outputToArray(final int[][] codePointArrays,
+            final boolean[] isBeginningOfSentenceArray) {
+        for (int i = 0; i < mPrevWordsInfo.length; i++) {
+            final WordInfo wordInfo = mPrevWordsInfo[i];
+            if (wordInfo == null || !wordInfo.isValid()) {
+                codePointArrays[i] = new int[0];
+                isBeginningOfSentenceArray[i] = false;
+                continue;
+            }
+            codePointArrays[i] = StringUtils.toCodePointArray(wordInfo.mWord);
+            isBeginningOfSentenceArray[i] = wordInfo.mIsBeginningOfSentence;
+        }
     }
 
     @Override
     public String toString() {
-        return "PrevWord: " + mPrevWord + ", isBeginningOfSentence: "
-                    + mIsBeginningOfSentence + ".";
+        final StringBuffer builder = new StringBuffer();
+        for (int i = 0; i < mPrevWordsInfo.length; i++) {
+            final WordInfo wordInfo = mPrevWordsInfo[i];
+            builder.append("PrevWord[");
+            builder.append(i);
+            builder.append("]: ");
+            if (!wordInfo.isValid()) {
+                builder.append("Empty. ");
+                continue;
+            }
+            builder.append(wordInfo.mWord);
+            builder.append(", isBeginningOfSentence: ");
+            builder.append(wordInfo.mIsBeginningOfSentence);
+            builder.append(". ");
+        }
+        return builder.toString();
     }
 }