1 files changed, 134 insertions, 0 deletions
diff --git a/java/src/com/android/inputmethod/latin/utils/UserLogRingCharBuffer.java b/java/src/com/android/inputmethod/latin/utils/UserLogRingCharBuffer.java
new file mode 100644
index 000000000..3e67e8216
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/utils/UserLogRingCharBuffer.java
@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.inputmethod.latin.utils;
+
+import android.inputmethodservice.InputMethodService;
+
+import com.android.inputmethod.annotations.UsedForTesting;
+import com.android.inputmethod.latin.Settings;
+import com.android.inputmethod.latin.utils.Utils.UsabilityStudyLogUtils;
+
+public final class UserLogRingCharBuffer {
+    public /* for test */ static final int BUFSIZE = 20;
+    public /* for test */ int mLength = 0;
+
+    private static UserLogRingCharBuffer sUserLogRingCharBuffer = new UserLogRingCharBuffer();
+    private static final char PLACEHOLDER_DELIMITER_CHAR = '\uFFFC';
+    private static final int INVALID_COORDINATE = -2;
+    private boolean mEnabled = false;
+    private int mEnd = 0;
+    private char[] mCharBuf = new char[BUFSIZE];
+    private int[] mXBuf = new int[BUFSIZE];
+    private int[] mYBuf = new int[BUFSIZE];
+
+    private UserLogRingCharBuffer() {
+        // Intentional empty constructor for singleton.
+    }
+
+    @UsedForTesting
+    public static UserLogRingCharBuffer getInstance() {
+        return sUserLogRingCharBuffer;
+    }
+
+    public static UserLogRingCharBuffer init(final InputMethodService context,
+            final boolean enabled, final boolean usabilityStudy) {
+        if (!(enabled || usabilityStudy)) {
+            return null;
+        }
+        sUserLogRingCharBuffer.mEnabled = true;
+        UsabilityStudyLogUtils.getInstance().init(context);
+        return sUserLogRingCharBuffer;
+    }
+
+    private static int normalize(final int in) {
+        int ret = in % BUFSIZE;
+        return ret < 0 ? ret + BUFSIZE : ret;
+    }
+
+    // TODO: accept code points
+    @UsedForTesting
+    public void push(final char c, final int x, final int y) {
+        if (!mEnabled) {
+            return;
+        }
+        mCharBuf[mEnd] = c;
+        mXBuf[mEnd] = x;
+        mYBuf[mEnd] = y;
+        mEnd = normalize(mEnd + 1);
+        if (mLength < BUFSIZE) {
+            ++mLength;
+        }
+    }
+
+    public char pop() {
+        if (mLength < 1) {
+            return PLACEHOLDER_DELIMITER_CHAR;
+        }
+        mEnd = normalize(mEnd - 1);
+        --mLength;
+        return mCharBuf[mEnd];
+    }
+
+    public char getBackwardNthChar(final int n) {
+        if (mLength <= n || n < 0) {
+            return PLACEHOLDER_DELIMITER_CHAR;
+        }
+        return mCharBuf[normalize(mEnd - n - 1)];
+    }
+
+    public int getPreviousX(final char c, final int back) {
+        final int index = normalize(mEnd - 2 - back);
+        if (mLength <= back
+                || Character.toLowerCase(c) != Character.toLowerCase(mCharBuf[index])) {
+            return INVALID_COORDINATE;
+        }
+        return mXBuf[index];
+    }
+
+    public int getPreviousY(final char c, final int back) {
+        int index = normalize(mEnd - 2 - back);
+        if (mLength <= back
+                || Character.toLowerCase(c) != Character.toLowerCase(mCharBuf[index])) {
+            return INVALID_COORDINATE;
+        }
+        return mYBuf[index];
+    }
+
+    public String getLastWord(final int ignoreCharCount) {
+        final StringBuilder sb = new StringBuilder();
+        int i = ignoreCharCount;
+        for (; i < mLength; ++i) {
+            final char c = mCharBuf[normalize(mEnd - 1 - i)];
+            if (!Settings.getInstance().isWordSeparator(c)) {
+                break;
+            }
+        }
+        for (; i < mLength; ++i) {
+            char c = mCharBuf[normalize(mEnd - 1 - i)];
+            if (!Settings.getInstance().isWordSeparator(c)) {
+                sb.append(c);
+            } else {
+                break;
+            }
+        }
+        return sb.reverse().toString();
+    }
+
+    public void reset() {
+        mLength = 0;
+    }
+}