Add getTerminalPosition.

Change-Id: If04d779db23b1aea2cc12e5e9b8cecfcb35a5737

java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java

@@ -16,10 +16,11 @@
 
 package com.android.inputmethod.latin.makedict;
 
-import com.android.inputmethod.latin.makedict.BinaryDictInputOutput;
+import com.android.inputmethod.latin.Constants;
 import com.android.inputmethod.latin.makedict.BinaryDictInputOutput.FusionDictionaryBufferInterface;
 import com.android.inputmethod.latin.makedict.FormatSpec.FileHeader;
 import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions;
+import com.android.inputmethod.latin.makedict.FusionDictionary.CharGroup;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -124,4 +125,69 @@ public class BinaryDictIOUtils {
         readUnigramsAndBigramsBinaryInner(buffer, header.mHeaderSize, words, frequencies, bigrams,
                 header.mFormatOptions);
     }
+
+    /**
+     * Gets the address of the last CharGroup of the exact matching word in the dictionary.
+     * If no match is found, returns NOT_VALID_WORD.
+     *
+     * @param buffer the buffer to read.
+     * @param word the word we search for.
+     * @return the address of the terminal node.
+     * @throws IOException
+     * @throws UnsupportedFormatException
+     */
+    public static int getTerminalPosition(final FusionDictionaryBufferInterface buffer,
+            final String word) throws IOException, UnsupportedFormatException {
+        if (word == null) return FormatSpec.NOT_VALID_WORD;
+        if (buffer.position() != 0) buffer.position(0);
+
+        final FileHeader header = BinaryDictInputOutput.readHeader(buffer);
+        int wordPos = 0;
+        final int wordLen = word.codePointCount(0, word.length());
+        for (int depth = 0; depth < Constants.Dictionary.MAX_WORD_LENGTH; ++depth) {
+            if (wordPos >= wordLen) return FormatSpec.NOT_VALID_WORD;
+            int groupOffset = buffer.position() - header.mHeaderSize;
+            final int charGroupCount = BinaryDictInputOutput.readCharGroupCount(buffer);
+            groupOffset += BinaryDictInputOutput.getGroupCountSize(charGroupCount);
+
+            for (int i = 0; i < charGroupCount; ++i) {
+                final int charGroupPos = buffer.position();
+                final CharGroupInfo currentInfo = BinaryDictInputOutput.readCharGroup(buffer,
+                        buffer.position(), header.mFormatOptions);
+                boolean same = true;
+                for (int p = 0, j = word.offsetByCodePoints(0, wordPos);
+                        p < currentInfo.mCharacters.length;
+                        ++p, j = word.offsetByCodePoints(j, 1)) {
+                    if (wordPos + p >= wordLen
+                            || word.codePointAt(j) != currentInfo.mCharacters[p]) {
+                        same = false;
+                        break;
+                    }
+                }
+
+                if (same) {
+                    if (wordPos + currentInfo.mCharacters.length == wordLen) {
+                        if (currentInfo.mFrequency == CharGroup.NOT_A_TERMINAL) {
+                            return FormatSpec.NOT_VALID_WORD;
+                        } else {
+                            return charGroupPos;
+                        }
+                    }
+                    wordPos += currentInfo.mCharacters.length;
+                    if (currentInfo.mChildrenAddress == FormatSpec.NO_CHILDREN_ADDRESS) {
+                        return FormatSpec.NOT_VALID_WORD;
+                    }
+                    buffer.position(currentInfo.mChildrenAddress);
+                    break;
+                }
+                groupOffset = currentInfo.mEndAddress;
+
+                // not found
+                if (i >= charGroupCount - 1) {
+                    return FormatSpec.NOT_VALID_WORD;
+                }
+            }
+        }
+        return FormatSpec.NOT_VALID_WORD;
+    }
 }

java/src/com/android/inputmethod/latin/makedict/BinaryDictInputOutput.java

@@ -1242,8 +1242,9 @@ public class BinaryDictInputOutput {
      * @param formatOptions file format options.
      * @return the word, as a string.
      */
-    private static String getWordAtAddress(final FusionDictionaryBufferInterface buffer,
-            final int headerSize, final int address, final FormatOptions formatOptions) {
+    /* packages for tests */ static String getWordAtAddress(
+            final FusionDictionaryBufferInterface buffer, final int headerSize, final int address,
+            final FormatOptions formatOptions) {
         final String cachedString = wordCache.get(address);
         if (null != cachedString) return cachedString;
 

java/src/com/android/inputmethod/latin/makedict/FormatSpec.java

@@ -207,6 +207,9 @@ public final class FormatSpec {
     static final int MAX_TERMINAL_FREQUENCY = 255;
     static final int MAX_BIGRAM_FREQUENCY = 15;
 
+    // This option needs to be the same numeric value as the one in binary_format.h.
+    static final int NOT_VALID_WORD = -99;
+
     /**
      * Options about file format.
      */

tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOTests.java

@@ -19,7 +19,7 @@ package com.android.inputmethod.latin.makedict;
 import com.android.inputmethod.latin.CollectionUtils;
 import com.android.inputmethod.latin.UserHistoryDictIOUtils;
 import com.android.inputmethod.latin.makedict.BinaryDictInputOutput.FusionDictionaryBufferInterface;
-import com.android.inputmethod.latin.makedict.FormatSpec;
+import com.android.inputmethod.latin.makedict.FormatSpec.FileHeader;
 import com.android.inputmethod.latin.makedict.FusionDictionary.CharGroup;
 import com.android.inputmethod.latin.makedict.FusionDictionary.Node;
 import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
@@ -475,4 +475,93 @@ public class BinaryDictIOTests extends AndroidTestCase {
             Log.d(TAG, result);
         }
     }
+
+    // Tests for getTerminalPosition
+    private String getWordFromBinary(final FusionDictionaryBufferInterface buffer,
+            final int address) {
+        if (buffer.position() != 0) buffer.position(0);
+
+        FileHeader header = null;
+        try {
+            header = BinaryDictInputOutput.readHeader(buffer);
+        } catch (IOException e) {
+            return null;
+        } catch (UnsupportedFormatException e) {
+            return null;
+        }
+        if (header == null) return null;
+        return BinaryDictInputOutput.getWordAtAddress(buffer, header.mHeaderSize,
+                address - header.mHeaderSize, header.mFormatOptions);
+    }
+
+    private long runGetTerminalPosition(final FusionDictionaryBufferInterface buffer,
+            final String word, int index, boolean contained) {
+        final int expectedFrequency = (UNIGRAM_FREQ + index) % 255;
+        long diff = -1;
+        int position = -1;
+        try {
+            final long now = System.nanoTime();
+            position = BinaryDictIOUtils.getTerminalPosition(buffer, word);
+            diff = System.nanoTime() - now;
+        } catch (IOException e) {
+            Log.e(TAG, "IOException while getTerminalPosition: " + e);
+        } catch (UnsupportedFormatException e) {
+            Log.e(TAG, "UnsupportedFormatException while getTermianlPosition: " + e);
+        }
+
+        assertEquals(FormatSpec.NOT_VALID_WORD != position, contained);
+        if (contained) assertEquals(getWordFromBinary(buffer, position), word);
+        return diff;
+    }
+
+    public void testGetTerminalPosition() {
+        File file = null;
+        try {
+            file = File.createTempFile("runReadUnigrams", ".dict");
+        } catch (IOException e) {
+            // do nothing
+        }
+        assertNotNull(file);
+
+        final FusionDictionary dict = new FusionDictionary(new Node(),
+                new FusionDictionary.DictionaryOptions(
+                        new HashMap<String, String>(), false, false));
+        addUnigrams(sWords.size(), dict, sWords, null /* shortcutMap */);
+        timeWritingDictToFile(file, dict, VERSION3_WITH_LINKEDLIST_NODE);
+
+        final FusionDictionaryBufferInterface buffer = getBuffer(file, USE_BYTE_ARRAY);
+
+        try {
+            // too long word
+            final String longWord = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";
+            assertEquals(FormatSpec.NOT_VALID_WORD,
+                    BinaryDictIOUtils.getTerminalPosition(buffer, longWord));
+
+            // null
+            assertEquals(FormatSpec.NOT_VALID_WORD,
+                    BinaryDictIOUtils.getTerminalPosition(buffer, null));
+
+            // empty string
+            assertEquals(FormatSpec.NOT_VALID_WORD,
+                    BinaryDictIOUtils.getTerminalPosition(buffer, ""));
+        } catch (IOException e) {
+        } catch (UnsupportedFormatException e) {
+        }
+
+        // Test a word that is contained within the dictionary.
+        long sum = 0;
+        for (int i = 0; i < sWords.size(); ++i) {
+            final long time = runGetTerminalPosition(buffer, sWords.get(i), i, true);
+            sum += time == -1 ? 0 : time;
+        }
+        Log.d(TAG, "per a search : " + (((double)sum) / sWords.size() / 1000000));
+
+        // Test a word that isn't contained within the dictionary.
+        final Random random = new Random((int)System.currentTimeMillis());
+        for (int i = 0; i < 1000; ++i) {
+            final String word = generateWord(random.nextInt());
+            if (sWords.indexOf(word) != -1) continue;
+            runGetTerminalPosition(buffer, word, i, false);
+        }
+    }
 }