Fix a bug with languages without spaces and predictions

This is simpler and more correct.

Change-Id: I41806d2fc12b4ca25f76e32972b38f91f3d05c2b

3 files changed, 51 insertions, 24 deletions

diff --git a/java/src/com/android/inputmethod/latin/LatinIME.java b/java/src/com/android/inputmethod/latin/LatinIME.java
index 1f6091e90..72d5435a8 100644
--- a/java/src/com/android/inputmethod/latin/LatinIME.java
+++ b/java/src/com/android/inputmethod/latin/LatinIME.java
@@ -1469,7 +1469,7 @@ public class LatinIME extends InputMethodService implements KeyboardActionListen
                 ResearchLogger.latinIME_maybeDoubleSpacePeriod(textToInsert,
                         false /* isBatchMode */);
             }
-            mWordComposer.doubleSpacePeriod();
+            mWordComposer.discardPreviousWordForSuggestion();
             mKeyboardSwitcher.updateShiftState();
             return true;
         }
@@ -2567,7 +2567,7 @@ public class LatinIME extends InputMethodService implements KeyboardActionListen
 
         if (DEBUG) {
             if (mWordComposer.isComposingWord() || mWordComposer.isBatchMode()) {
-                final String previousWord = mWordComposer.getPreviousWord();
+                final String previousWord = mWordComposer.getPreviousWordForSuggestion();
                 // TODO: this is for checking consistency with older versions. Remove this when
                 // we are confident this is stable.
                 // We're checking the previous word in the text field against the memorized previous
@@ -2581,7 +2581,7 @@ public class LatinIME extends InputMethodService implements KeyboardActionListen
                 }
             }
         }
-        suggest.getSuggestedWords(mWordComposer, mWordComposer.getPreviousWord(),
+        suggest.getSuggestedWords(mWordComposer, mWordComposer.getPreviousWordForSuggestion(),
                 keyboard.getProximityInfo(),
                 currentSettings.mBlockPotentiallyOffensive, currentSettings.mCorrectionEnabled,
                 additionalFeaturesOptions, sessionId, sequenceNumber, callback);
@@ -2824,6 +2824,19 @@ public class LatinIME extends InputMethodService implements KeyboardActionListen
         // strings.
         mLastComposedWord = mWordComposer.commitWord(commitType, chosenWord, separatorString,
                 prevWord);
+        final boolean shouldDiscardPreviousWordForSuggestion;
+        if (0 == StringUtils.codePointCount(separatorString)) {
+            // Separator is 0-length. Discard the word only if the current language has spaces.
+            shouldDiscardPreviousWordForSuggestion =
+                    mSettings.getCurrent().mCurrentLanguageHasSpaces;
+        } else {
+            // Otherwise, we discard if the separator contains any non-whitespace.
+            shouldDiscardPreviousWordForSuggestion =
+                    !StringUtils.containsOnlyWhitespace(separatorString);
+        }
+        if (shouldDiscardPreviousWordForSuggestion) {
+            mWordComposer.discardPreviousWordForSuggestion();
+        }
     }
 
     private void setPunctuationSuggestions() {
diff --git a/java/src/com/android/inputmethod/latin/WordComposer.java b/java/src/com/android/inputmethod/latin/WordComposer.java
index 5ecfc67b2..7da97e57a 100644
--- a/java/src/com/android/inputmethod/latin/WordComposer.java
+++ b/java/src/com/android/inputmethod/latin/WordComposer.java
@@ -50,8 +50,9 @@ public final class WordComposer {
     private final StringBuilder mTypedWord;
     // The previous word (before the composing word). Used as context for suggestions. May be null
     // after resetting and before starting a new composing word, or when there is no context like
-    // at the start of text for example.
-    private String mPreviousWord;
+    // at the start of text for example. It can also be set to null externally when the user
+    // enters a separator that does not let bigrams across, like a period or a comma.
+    private String mPreviousWordForSuggestion;
     private String mAutoCorrection;
     private boolean mIsResumed;
     private boolean mIsBatchMode;
@@ -89,7 +90,7 @@ public final class WordComposer {
         mIsBatchMode = false;
         mCursorPositionWithinWord = 0;
         mRejectedBatchModeSuggestion = null;
-        mPreviousWord = null;
+        mPreviousWordForSuggestion = null;
         refreshSize();
     }
 
@@ -106,7 +107,7 @@ public final class WordComposer {
         mIsBatchMode = source.mIsBatchMode;
         mCursorPositionWithinWord = source.mCursorPositionWithinWord;
         mRejectedBatchModeSuggestion = source.mRejectedBatchModeSuggestion;
-        mPreviousWord = source.mPreviousWord;
+        mPreviousWordForSuggestion = source.mPreviousWordForSuggestion;
         refreshSize();
     }
 
@@ -124,7 +125,7 @@ public final class WordComposer {
         mIsBatchMode = false;
         mCursorPositionWithinWord = 0;
         mRejectedBatchModeSuggestion = null;
-        mPreviousWord = null;
+        mPreviousWordForSuggestion = null;
         refreshSize();
     }
 
@@ -305,7 +306,7 @@ public final class WordComposer {
             addKeyInfo(codePoint, keyboard);
         }
         mIsResumed = true;
-        mPreviousWord = previousWord;
+        mPreviousWordForSuggestion = previousWord;
     }
 
     /**
@@ -356,8 +357,8 @@ public final class WordComposer {
         return mTypedWord.toString();
     }
 
-    public String getPreviousWord() {
-        return mPreviousWord;
+    public String getPreviousWordForSuggestion() {
+        return mPreviousWordForSuggestion;
     }
 
     /**
@@ -419,7 +420,7 @@ public final class WordComposer {
     public void setCapitalizedModeAndPreviousWordAtStartComposingTime(final int mode,
             final String previousWord) {
         mCapitalizedMode = mode;
-        mPreviousWord = previousWord;
+        mPreviousWordForSuggestion = previousWord;
     }
 
     /**
@@ -471,12 +472,7 @@ public final class WordComposer {
         mCapsCount = 0;
         mDigitsCount = 0;
         mIsBatchMode = false;
-        final boolean isWhitespace = 1 == StringUtils.codePointCount(separatorString)
-                && Character.isWhitespace(separatorString.codePointAt(0));
-        // If not whitespace, we don't use the previous word for suggestion. This is consistent
-        // with how we get the previous word for suggestion: see RichInputConnection#spaceRegex and
-        // LatinIME#getNthPreviousWordForSuggestion.
-        mPreviousWord = isWhitespace ? mTypedWord.toString() : null;
+        mPreviousWordForSuggestion = mTypedWord.toString();
         mTypedWord.setLength(0);
         mCodePointSize = 0;
         mTrailingSingleQuotesCount = 0;
@@ -490,11 +486,11 @@ public final class WordComposer {
         return lastComposedWord;
     }
 
-    public void doubleSpacePeriod() {
-        // When a period was entered with a double space, the separator we got has been
-        // changed by a period (see #commitWord). We should not use the previous word for
-        // suggestion.
-        mPreviousWord = null;
+    // Call this when the recorded previous word should be discarded. This is typically called
+    // when the user inputs a separator that's not whitespace (including the case of the
+    // double-space-to-period feature).
+    public void discardPreviousWordForSuggestion() {
+        mPreviousWordForSuggestion = null;
     }
 
     public void resumeSuggestionOnLastComposedWord(final LastComposedWord lastComposedWord,
@@ -509,7 +505,7 @@ public final class WordComposer {
         mCursorPositionWithinWord = mCodePointSize;
         mRejectedBatchModeSuggestion = null;
         mIsResumed = true;
-        mPreviousWord = previousWord;
+        mPreviousWordForSuggestion = previousWord;
     }
 
     public boolean isBatchMode() {
diff --git a/java/src/com/android/inputmethod/latin/utils/StringUtils.java b/java/src/com/android/inputmethod/latin/utils/StringUtils.java
index df420417d..85f44541e 100644
--- a/java/src/com/android/inputmethod/latin/utils/StringUtils.java
+++ b/java/src/com/android/inputmethod/latin/utils/StringUtils.java
@@ -250,6 +250,24 @@ public final class StringUtils {
         return true;
     }
 
+    /**
+     * Returns true if all code points in text are whitespace, false otherwise. Empty is true.
+     */
+    // Interestingly enough, U+00A0 NO-BREAK SPACE and U+200B ZERO-WIDTH SPACE are not considered
+    // whitespace, while EN SPACE, EM SPACE and IDEOGRAPHIC SPACES are.
+    public static boolean containsOnlyWhitespace(final String text) {
+        final int length = text.length();
+        int i = 0;
+        while (i < length) {
+            final int codePoint = text.codePointAt(i);
+            if (!Character.isWhitespace(codePoint)) {
+                return false;
+            }
+            i += Character.charCount(codePoint);
+        }
+        return true;
+    }
+
     @UsedForTesting
     public static boolean looksValidForDictionaryInsertion(final CharSequence text,
             final SettingsValues settings) {