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Commit 21a28abc authored by Chieu Nguyen's avatar Chieu Nguyen
Browse files

Handle empty previous ngram context correctly. 

Fixes bug where empty previous ngram context not at the
beginning of a sentence incorrectly returned the
beginning-of-sentence marker.

Bug: 19612336
Change-Id: I5ddf3408e20dcedf70487b85c983cd3fc12550e7
parent 37503590

java/src/com/android/inputmethod/latin/NgramContext.java

+2 −5
Original line number Diff line number Diff line
@@ -142,8 +142,7 @@ public class NgramContext { 
                }

            }

        }

        return terms.size() == 0 ? BEGINNING_OF_SENTENCE_TAG

                : TextUtils.join(CONTEXT_SEPARATOR, terms);

        return TextUtils.join(CONTEXT_SEPARATOR, terms);

    }



    /**
@@ -166,9 +165,7 @@ public class NgramContext { 
                }

            }

        }

        final String[] contextStringArray = prevTermList.size() == 0 ?

                new String[] { BEGINNING_OF_SENTENCE_TAG }

                : prevTermList.toArray(new String[prevTermList.size()]);

        final String[] contextStringArray = prevTermList.toArray(new String[prevTermList.size()]);

        return contextStringArray;

    }

tests/src/com/android/inputmethod/latin/NgramContextTests.java

+17 −0
Original line number Diff line number Diff line
@@ -81,15 +81,24 @@ public class NgramContextTests extends AndroidTestCase { 
        assertTrue(ngramContext_bos_b.isBeginningOfSentenceContext());

        assertEquals("b", ngramContext_bos_b.getNthPrevWord(2));

        assertEquals("a b <S>", ngramContext_bos_b.extractPrevWordsContext());



        final NgramContext ngramContext_empty = new NgramContext(WordInfo.EMPTY_WORD_INFO);

        assertEquals("", ngramContext_empty.extractPrevWordsContext());

        final NgramContext ngramContext_a_empty =

                ngramContext_empty.getNextNgramContext(new WordInfo("a"));

        assertEquals("a", ngramContext_a_empty.getNthPrevWord(1));

        assertEquals("a", ngramContext_a_empty.extractPrevWordsContext());

    }



    public void testExtractPrevWordsContextArray() {

        final NgramContext ngramContext_bos =

                new NgramContext(WordInfo.BEGINNING_OF_SENTENCE_WORD_INFO);

        assertEquals("<S>", ngramContext_bos.extractPrevWordsContext());

        assertEquals(1, ngramContext_bos.extractPrevWordsContextArray().length);

        final NgramContext ngramContext_a = new NgramContext(new WordInfo("a"));

        final NgramContext ngramContext_b_a =

                ngramContext_a.getNextNgramContext(new WordInfo("b"));

        assertEquals(2, ngramContext_b_a.extractPrevWordsContextArray().length);

        assertEquals("b", ngramContext_b_a.getNthPrevWord(1));

        assertEquals("a", ngramContext_b_a.getNthPrevWord(2));

        assertEquals("a", ngramContext_b_a.extractPrevWordsContextArray()[0]);
@@ -98,9 +107,17 @@ public class NgramContextTests extends AndroidTestCase { 
        final NgramContext ngramContext_bos_b =

                ngramContext_b_a.getNextNgramContext(WordInfo.BEGINNING_OF_SENTENCE_WORD_INFO);

        assertTrue(ngramContext_bos_b.isBeginningOfSentenceContext());

        assertEquals(3, ngramContext_bos_b.extractPrevWordsContextArray().length);

        assertEquals("b", ngramContext_bos_b.getNthPrevWord(2));

        assertEquals("a", ngramContext_bos_b.extractPrevWordsContextArray()[0]);

        assertEquals("b", ngramContext_bos_b.extractPrevWordsContextArray()[1]);

        assertEquals("<S>", ngramContext_bos_b.extractPrevWordsContextArray()[2]);



        final NgramContext ngramContext_empty = new NgramContext(WordInfo.EMPTY_WORD_INFO);

        assertEquals(0, ngramContext_empty.extractPrevWordsContextArray().length);

        final NgramContext ngramContext_a_empty =

                ngramContext_empty.getNextNgramContext(new WordInfo("a"));

        assertEquals(1, ngramContext_a_empty.extractPrevWordsContextArray().length);

        assertEquals("a", ngramContext_a_empty.extractPrevWordsContextArray()[0]);

    }

}