Add a utility method to SuggestionSpanUtils

This is a ground work for subsequent CLs.

BUG: 16995261
Change-Id: Icbb708a35412a635a0d625b520069840c0bb0904

java/src/com/android/inputmethod/compat/SuggestionSpanUtils.java

@@ -28,9 +28,13 @@ import com.android.inputmethod.latin.SuggestedWords;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
 import com.android.inputmethod.latin.SuggestionSpanPickedNotificationReceiver;
 import com.android.inputmethod.latin.define.DebugFlags;
+import com.android.inputmethod.latin.utils.LocaleUtils;
 
 import java.lang.reflect.Field;
 import java.util.ArrayList;
+import java.util.Locale;
+
+import javax.annotation.Nullable;
 
 public final class SuggestionSpanUtils {
     // Note that SuggestionSpan.FLAG_AUTO_CORRECTION has been introduced
@@ -98,4 +102,28 @@ public final class SuggestionSpanUtils {
         spannable.setSpan(suggestionSpan, 0, pickedWord.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
         return spannable;
     }
+
+    /**
+     * Returns first {@link Locale} found in the given array of {@link SuggestionSpan}.
+     * @param suggestionSpans the array of {@link SuggestionSpan} to be examined.
+     * @return the first {@link Locale} found in {@code suggestionSpans}. {@code null} when not
+     * found.
+     */
+    @UsedForTesting
+    @Nullable
+    public static Locale findFirstLocaleFromSuggestionSpans(
+            final SuggestionSpan[] suggestionSpans) {
+        for (final SuggestionSpan suggestionSpan : suggestionSpans) {
+            final String localeString = suggestionSpan.getLocale();
+            if (TextUtils.isEmpty(localeString)) {
+                continue;
+            }
+            final Locale locale = LocaleUtils.constructLocaleFromString(localeString);
+            if (locale == null) {
+                continue;
+            }
+            return locale;
+        }
+        return null;
+    }
 }

tests/src/com/android/inputmethod/compat/SuggestionSpanUtilsTest.java

@@ -178,4 +178,30 @@ public class SuggestionSpanUtilsTest extends AndroidTestCase {
                             typedAndCollectedWords));
         }
     }
+
+    public void testFindFirstLocaleFromSuggestionSpans() {
+        final String[] suggestions = new String[] {"Quality", "Speed", "Price"};
+        final SuggestionSpan nullLocaleSpan = new SuggestionSpan((Locale)null, suggestions, 0);
+        final SuggestionSpan emptyLocaleSpan = new SuggestionSpan(new Locale(""), suggestions, 0);
+        final SuggestionSpan enUsLocaleSpan = new SuggestionSpan(Locale.US, suggestions, 0);
+        final SuggestionSpan jaJpLocaleSpan = new SuggestionSpan(Locale.JAPAN, suggestions, 0);
+
+        assertEquals(null, SuggestionSpanUtils.findFirstLocaleFromSuggestionSpans(
+                new SuggestionSpan[] {}));
+
+        assertEquals(null, SuggestionSpanUtils.findFirstLocaleFromSuggestionSpans(
+                new SuggestionSpan[] {emptyLocaleSpan}));
+
+        assertEquals(Locale.US, SuggestionSpanUtils.findFirstLocaleFromSuggestionSpans(
+                new SuggestionSpan[] {enUsLocaleSpan}));
+
+        assertEquals(Locale.US, SuggestionSpanUtils.findFirstLocaleFromSuggestionSpans(
+                new SuggestionSpan[] {nullLocaleSpan, enUsLocaleSpan}));
+
+        assertEquals(Locale.US, SuggestionSpanUtils.findFirstLocaleFromSuggestionSpans(
+                new SuggestionSpan[] {nullLocaleSpan, emptyLocaleSpan, enUsLocaleSpan}));
+
+        assertEquals(Locale.JAPAN, SuggestionSpanUtils.findFirstLocaleFromSuggestionSpans(
+                new SuggestionSpan[] {nullLocaleSpan, jaJpLocaleSpan, enUsLocaleSpan}));
+    }
 }