Rename to Kelar Keyboard (org.kelar.inputmethod.latin)

1 files changed, 1033 insertions, 0 deletions

diff --git a/java/src/org/kelar/inputmethod/latin/RichInputConnection.java b/java/src/org/kelar/inputmethod/latin/RichInputConnection.java
new file mode 100644
index 000000000..381560945
--- /dev/null
+++ b/java/src/org/kelar/inputmethod/latin/RichInputConnection.java
@@ -0,0 +1,1033 @@
+/*
+ * Copyright (C) 2012 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 org.kelar.inputmethod.latin;
+
+import android.inputmethodservice.InputMethodService;
+import android.os.Build;
+import android.os.Bundle;
+import android.os.SystemClock;
+import android.text.SpannableStringBuilder;
+import android.text.TextUtils;
+import android.text.style.CharacterStyle;
+import android.util.Log;
+import android.view.KeyEvent;
+import android.view.inputmethod.CompletionInfo;
+import android.view.inputmethod.CorrectionInfo;
+import android.view.inputmethod.ExtractedText;
+import android.view.inputmethod.ExtractedTextRequest;
+import android.view.inputmethod.InputConnection;
+import android.view.inputmethod.InputMethodManager;
+
+import org.kelar.inputmethod.compat.InputConnectionCompatUtils;
+import org.kelar.inputmethod.latin.common.Constants;
+import org.kelar.inputmethod.latin.common.UnicodeSurrogate;
+import org.kelar.inputmethod.latin.common.StringUtils;
+import org.kelar.inputmethod.latin.inputlogic.PrivateCommandPerformer;
+import org.kelar.inputmethod.latin.settings.SpacingAndPunctuations;
+import org.kelar.inputmethod.latin.utils.CapsModeUtils;
+import org.kelar.inputmethod.latin.utils.DebugLogUtils;
+import org.kelar.inputmethod.latin.utils.NgramContextUtils;
+import org.kelar.inputmethod.latin.utils.ScriptUtils;
+import org.kelar.inputmethod.latin.utils.SpannableStringUtils;
+import org.kelar.inputmethod.latin.utils.StatsUtils;
+import org.kelar.inputmethod.latin.utils.TextRange;
+
+import java.util.concurrent.TimeUnit;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+/**
+ * Enrichment class for InputConnection to simplify interaction and add functionality.
+ *
+ * This class serves as a wrapper to be able to simply add hooks to any calls to the underlying
+ * InputConnection. It also keeps track of a number of things to avoid having to call upon IPC
+ * all the time to find out what text is in the buffer, when we need it to determine caps mode
+ * for example.
+ */
+public final class RichInputConnection implements PrivateCommandPerformer {
+    private static final String TAG = "RichInputConnection";
+    private static final boolean DBG = false;
+    private static final boolean DEBUG_PREVIOUS_TEXT = false;
+    private static final boolean DEBUG_BATCH_NESTING = false;
+    private static final int NUM_CHARS_TO_GET_BEFORE_CURSOR = 40;
+    private static final int NUM_CHARS_TO_GET_AFTER_CURSOR = 40;
+    private static final int INVALID_CURSOR_POSITION = -1;
+
+    /**
+     * The amount of time a {@link #reloadTextCache} call needs to take for the keyboard to enter
+     * the {@link #hasSlowInputConnection} state.
+     */
+    private static final long SLOW_INPUT_CONNECTION_ON_FULL_RELOAD_MS = 1000;
+    /**
+     * The amount of time a {@link #getTextBeforeCursor} or {@link #getTextAfterCursor} call needs
+     * to take for the keyboard to enter the {@link #hasSlowInputConnection} state.
+     */
+    private static final long SLOW_INPUT_CONNECTION_ON_PARTIAL_RELOAD_MS = 200;
+
+    private static final int OPERATION_GET_TEXT_BEFORE_CURSOR = 0;
+    private static final int OPERATION_GET_TEXT_AFTER_CURSOR = 1;
+    private static final int OPERATION_GET_WORD_RANGE_AT_CURSOR = 2;
+    private static final int OPERATION_RELOAD_TEXT_CACHE = 3;
+    private static final String[] OPERATION_NAMES = new String[] {
+            "GET_TEXT_BEFORE_CURSOR",
+            "GET_TEXT_AFTER_CURSOR",
+            "GET_WORD_RANGE_AT_CURSOR",
+            "RELOAD_TEXT_CACHE"};
+
+    /**
+     * The amount of time the keyboard will persist in the {@link #hasSlowInputConnection} state
+     * after observing a slow InputConnection event.
+     */
+    private static final long SLOW_INPUTCONNECTION_PERSIST_MS = TimeUnit.MINUTES.toMillis(10);
+
+    /**
+     * This variable contains an expected value for the selection start position. This is where the
+     * cursor or selection start may end up after all the keyboard-triggered updates have passed. We
+     * keep this to compare it to the actual selection start to guess whether the move was caused by
+     * a keyboard command or not.
+     * It's not really the selection start position: the selection start may not be there yet, and
+     * in some cases, it may never arrive there.
+     */
+    private int mExpectedSelStart = INVALID_CURSOR_POSITION; // in chars, not code points
+    /**
+     * The expected selection end.  Only differs from mExpectedSelStart if a non-empty selection is
+     * expected.  The same caveats as mExpectedSelStart apply.
+     */
+    private int mExpectedSelEnd = INVALID_CURSOR_POSITION; // in chars, not code points
+    /**
+     * This contains the committed text immediately preceding the cursor and the composing
+     * text, if any. It is refreshed when the cursor moves by calling upon the TextView.
+     */
+    private final StringBuilder mCommittedTextBeforeComposingText = new StringBuilder();
+    /**
+     * This contains the currently composing text, as LatinIME thinks the TextView is seeing it.
+     */
+    private final StringBuilder mComposingText = new StringBuilder();
+
+    /**
+     * This variable is a temporary object used in {@link #commitText(CharSequence,int)}
+     * to avoid object creation.
+     */
+    private SpannableStringBuilder mTempObjectForCommitText = new SpannableStringBuilder();
+
+    private final InputMethodService mParent;
+    private InputConnection mIC;
+    private int mNestLevel;
+
+    /**
+     * The timestamp of the last slow InputConnection operation
+     */
+    private long mLastSlowInputConnectionTime = -SLOW_INPUTCONNECTION_PERSIST_MS;
+
+    public RichInputConnection(final InputMethodService parent) {
+        mParent = parent;
+        mIC = null;
+        mNestLevel = 0;
+    }
+
+    public boolean isConnected() {
+        return mIC != null;
+    }
+
+    /**
+     * Returns whether or not the underlying InputConnection is slow. When true, we want to avoid
+     * calling InputConnection methods that trigger an IPC round-trip (e.g., getTextAfterCursor).
+     */
+    public boolean hasSlowInputConnection() {
+        return (SystemClock.uptimeMillis() - mLastSlowInputConnectionTime)
+                        <= SLOW_INPUTCONNECTION_PERSIST_MS;
+    }
+
+    public void onStartInput() {
+        mLastSlowInputConnectionTime = -SLOW_INPUTCONNECTION_PERSIST_MS;
+    }
+
+    private void checkConsistencyForDebug() {
+        final ExtractedTextRequest r = new ExtractedTextRequest();
+        r.hintMaxChars = 0;
+        r.hintMaxLines = 0;
+        r.token = 1;
+        r.flags = 0;
+        final ExtractedText et = mIC.getExtractedText(r, 0);
+        final CharSequence beforeCursor = getTextBeforeCursor(Constants.EDITOR_CONTENTS_CACHE_SIZE,
+                0);
+        final StringBuilder internal = new StringBuilder(mCommittedTextBeforeComposingText)
+                .append(mComposingText);
+        if (null == et || null == beforeCursor) return;
+        final int actualLength = Math.min(beforeCursor.length(), internal.length());
+        if (internal.length() > actualLength) {
+            internal.delete(0, internal.length() - actualLength);
+        }
+        final String reference = (beforeCursor.length() <= actualLength) ? beforeCursor.toString()
+                : beforeCursor.subSequence(beforeCursor.length() - actualLength,
+                        beforeCursor.length()).toString();
+        if (et.selectionStart != mExpectedSelStart
+                || !(reference.equals(internal.toString()))) {
+            final String context = "Expected selection start = " + mExpectedSelStart
+                    + "\nActual selection start = " + et.selectionStart
+                    + "\nExpected text = " + internal.length() + " " + internal
+                    + "\nActual text = " + reference.length() + " " + reference;
+            ((LatinIME)mParent).debugDumpStateAndCrashWithException(context);
+        } else {
+            Log.e(TAG, DebugLogUtils.getStackTrace(2));
+            Log.e(TAG, "Exp <> Actual : " + mExpectedSelStart + " <> " + et.selectionStart);
+        }
+    }
+
+    public void beginBatchEdit() {
+        if (++mNestLevel == 1) {
+            mIC = mParent.getCurrentInputConnection();
+            if (isConnected()) {
+                mIC.beginBatchEdit();
+            }
+        } else {
+            if (DBG) {
+                throw new RuntimeException("Nest level too deep");
+            }
+            Log.e(TAG, "Nest level too deep : " + mNestLevel);
+        }
+        if (DEBUG_BATCH_NESTING) checkBatchEdit();
+        if (DEBUG_PREVIOUS_TEXT) checkConsistencyForDebug();
+    }
+
+    public void endBatchEdit() {
+        if (mNestLevel <= 0) Log.e(TAG, "Batch edit not in progress!"); // TODO: exception instead
+        if (--mNestLevel == 0 && isConnected()) {
+            mIC.endBatchEdit();
+        }
+        if (DEBUG_PREVIOUS_TEXT) checkConsistencyForDebug();
+    }
+
+    /**
+     * Reset the cached text and retrieve it again from the editor.
+     *
+     * This should be called when the cursor moved. It's possible that we can't connect to
+     * the application when doing this; notably, this happens sometimes during rotation, probably
+     * because of a race condition in the framework. In this case, we just can't retrieve the
+     * data, so we empty the cache and note that we don't know the new cursor position, and we
+     * return false so that the caller knows about this and can retry later.
+     *
+     * @param newSelStart the new position of the selection start, as received from the system.
+     * @param newSelEnd the new position of the selection end, as received from the system.
+     * @param shouldFinishComposition whether we should finish the composition in progress.
+     * @return true if we were able to connect to the editor successfully, false otherwise. When
+     *   this method returns false, the caches could not be correctly refreshed so they were only
+     *   reset: the caller should try again later to return to normal operation.
+     */
+    public boolean resetCachesUponCursorMoveAndReturnSuccess(final int newSelStart,
+            final int newSelEnd, final boolean shouldFinishComposition) {
+        mExpectedSelStart = newSelStart;
+        mExpectedSelEnd = newSelEnd;
+        mComposingText.setLength(0);
+        final boolean didReloadTextSuccessfully = reloadTextCache();
+        if (!didReloadTextSuccessfully) {
+            Log.d(TAG, "Will try to retrieve text later.");
+            return false;
+        }
+        if (isConnected() && shouldFinishComposition) {
+            mIC.finishComposingText();
+        }
+        return true;
+    }
+
+    /**
+     * Reload the cached text from the InputConnection.
+     *
+     * @return true if successful
+     */
+    private boolean reloadTextCache() {
+        mCommittedTextBeforeComposingText.setLength(0);
+        mIC = mParent.getCurrentInputConnection();
+        // Call upon the inputconnection directly since our own method is using the cache, and
+        // we want to refresh it.
+        final CharSequence textBeforeCursor = getTextBeforeCursorAndDetectLaggyConnection(
+                OPERATION_RELOAD_TEXT_CACHE,
+                SLOW_INPUT_CONNECTION_ON_FULL_RELOAD_MS,
+                Constants.EDITOR_CONTENTS_CACHE_SIZE,
+                0 /* flags */);
+        if (null == textBeforeCursor) {
+            // For some reason the app thinks we are not connected to it. This looks like a
+            // framework bug... Fall back to ground state and return false.
+            mExpectedSelStart = INVALID_CURSOR_POSITION;
+            mExpectedSelEnd = INVALID_CURSOR_POSITION;
+            Log.e(TAG, "Unable to connect to the editor to retrieve text.");
+            return false;
+        }
+        mCommittedTextBeforeComposingText.append(textBeforeCursor);
+        return true;
+    }
+
+    private void checkBatchEdit() {
+        if (mNestLevel != 1) {
+            // TODO: exception instead
+            Log.e(TAG, "Batch edit level incorrect : " + mNestLevel);
+            Log.e(TAG, DebugLogUtils.getStackTrace(4));
+        }
+    }
+
+    public void finishComposingText() {
+        if (DEBUG_BATCH_NESTING) checkBatchEdit();
+        if (DEBUG_PREVIOUS_TEXT) checkConsistencyForDebug();
+        // TODO: this is not correct! The cursor is not necessarily after the composing text.
+        // In the practice right now this is only called when input ends so it will be reset so
+        // it works, but it's wrong and should be fixed.
+        mCommittedTextBeforeComposingText.append(mComposingText);
+        mComposingText.setLength(0);
+        if (isConnected()) {
+            mIC.finishComposingText();
+        }
+    }
+
+    /**
+     * Calls {@link InputConnection#commitText(CharSequence, int)}.
+     *
+     * @param text The text to commit. This may include styles.
+     * @param newCursorPosition The new cursor position around the text.
+     */
+    public void commitText(final CharSequence text, final int newCursorPosition) {
+        if (DEBUG_BATCH_NESTING) checkBatchEdit();
+        if (DEBUG_PREVIOUS_TEXT) checkConsistencyForDebug();
+        mCommittedTextBeforeComposingText.append(text);
+        // TODO: the following is exceedingly error-prone. Right now when the cursor is in the
+        // middle of the composing word mComposingText only holds the part of the composing text
+        // that is before the cursor, so this actually works, but it's terribly confusing. Fix this.
+        mExpectedSelStart += text.length() - mComposingText.length();
+        mExpectedSelEnd = mExpectedSelStart;
+        mComposingText.setLength(0);
+        if (isConnected()) {
+            mTempObjectForCommitText.clear();
+            mTempObjectForCommitText.append(text);
+            final CharacterStyle[] spans = mTempObjectForCommitText.getSpans(
+                    0, text.length(), CharacterStyle.class);
+            for (final CharacterStyle span : spans) {
+                final int spanStart = mTempObjectForCommitText.getSpanStart(span);
+                final int spanEnd = mTempObjectForCommitText.getSpanEnd(span);
+                final int spanFlags = mTempObjectForCommitText.getSpanFlags(span);
+                // We have to adjust the end of the span to include an additional character.
+                // This is to avoid splitting a unicode surrogate pair.
+                // See org.kelar.inputmethod.latin.common.Constants.UnicodeSurrogate
+                // See https://b.corp.google.com/issues/19255233
+                if (0 < spanEnd && spanEnd < mTempObjectForCommitText.length()) {
+                    final char spanEndChar = mTempObjectForCommitText.charAt(spanEnd - 1);
+                    final char nextChar = mTempObjectForCommitText.charAt(spanEnd);
+                    if (UnicodeSurrogate.isLowSurrogate(spanEndChar)
+                            && UnicodeSurrogate.isHighSurrogate(nextChar)) {
+                        mTempObjectForCommitText.setSpan(span, spanStart, spanEnd + 1, spanFlags);
+                    }
+                }
+            }
+            mIC.commitText(mTempObjectForCommitText, newCursorPosition);
+        }
+    }
+
+    @Nullable
+    public CharSequence getSelectedText(final int flags) {
+        return isConnected() ?  mIC.getSelectedText(flags) : null;
+    }
+
+    public boolean canDeleteCharacters() {
+        return mExpectedSelStart > 0;
+    }
+
+    /**
+     * Gets the caps modes we should be in after this specific string.
+     *
+     * This returns a bit set of TextUtils#CAP_MODE_*, masked by the inputType argument.
+     * This method also supports faking an additional space after the string passed in argument,
+     * to support cases where a space will be added automatically, like in phantom space
+     * state for example.
+     * Note that for English, we are using American typography rules (which are not specific to
+     * American English, it's just the most common set of rules for English).
+     *
+     * @param inputType a mask of the caps modes to test for.
+     * @param spacingAndPunctuations the values of the settings to use for locale and separators.
+     * @param hasSpaceBefore if we should consider there should be a space after the string.
+     * @return the caps modes that should be on as a set of bits
+     */
+    public int getCursorCapsMode(final int inputType,
+            final SpacingAndPunctuations spacingAndPunctuations, final boolean hasSpaceBefore) {
+        mIC = mParent.getCurrentInputConnection();
+        if (!isConnected()) {
+            return Constants.TextUtils.CAP_MODE_OFF;
+        }
+        if (!TextUtils.isEmpty(mComposingText)) {
+            if (hasSpaceBefore) {
+                // If we have some composing text and a space before, then we should have
+                // MODE_CHARACTERS and MODE_WORDS on.
+                return (TextUtils.CAP_MODE_CHARACTERS | TextUtils.CAP_MODE_WORDS) & inputType;
+            }
+            // We have some composing text - we should be in MODE_CHARACTERS only.
+            return TextUtils.CAP_MODE_CHARACTERS & inputType;
+        }
+        // TODO: this will generally work, but there may be cases where the buffer contains SOME
+        // information but not enough to determine the caps mode accurately. This may happen after
+        // heavy pressing of delete, for example DEFAULT_TEXT_CACHE_SIZE - 5 times or so.
+        // getCapsMode should be updated to be able to return a "not enough info" result so that
+        // we can get more context only when needed.
+        if (TextUtils.isEmpty(mCommittedTextBeforeComposingText) && 0 != mExpectedSelStart) {
+            if (!reloadTextCache()) {
+                Log.w(TAG, "Unable to connect to the editor. "
+                        + "Setting caps mode without knowing text.");
+            }
+        }
+        // This never calls InputConnection#getCapsMode - in fact, it's a static method that
+        // never blocks or initiates IPC.
+        // TODO: don't call #toString() here. Instead, all accesses to
+        // mCommittedTextBeforeComposingText should be done on the main thread.
+        return CapsModeUtils.getCapsMode(mCommittedTextBeforeComposingText.toString(), inputType,
+                spacingAndPunctuations, hasSpaceBefore);
+    }
+
+    public int getCodePointBeforeCursor() {
+        final int length = mCommittedTextBeforeComposingText.length();
+        if (length < 1) return Constants.NOT_A_CODE;
+        return Character.codePointBefore(mCommittedTextBeforeComposingText, length);
+    }
+
+    public CharSequence getTextBeforeCursor(final int n, final int flags) {
+        final int cachedLength =
+                mCommittedTextBeforeComposingText.length() + mComposingText.length();
+        // If we have enough characters to satisfy the request, or if we have all characters in
+        // the text field, then we can return the cached version right away.
+        // However, if we don't have an expected cursor position, then we should always
+        // go fetch the cache again (as it happens, INVALID_CURSOR_POSITION < 0, so we need to
+        // test for this explicitly)
+        if (INVALID_CURSOR_POSITION != mExpectedSelStart
+                && (cachedLength >= n || cachedLength >= mExpectedSelStart)) {
+            final StringBuilder s = new StringBuilder(mCommittedTextBeforeComposingText);
+            // We call #toString() here to create a temporary object.
+            // In some situations, this method is called on a worker thread, and it's possible
+            // the main thread touches the contents of mComposingText while this worker thread
+            // is suspended, because mComposingText is a StringBuilder. This may lead to crashes,
+            // so we call #toString() on it. That will result in the return value being strictly
+            // speaking wrong, but since this is used for basing bigram probability off, and
+            // it's only going to matter for one getSuggestions call, it's fine in the practice.
+            s.append(mComposingText.toString());
+            if (s.length() > n) {
+                s.delete(0, s.length() - n);
+            }
+            return s;
+        }
+        return getTextBeforeCursorAndDetectLaggyConnection(
+                OPERATION_GET_TEXT_BEFORE_CURSOR,
+                SLOW_INPUT_CONNECTION_ON_PARTIAL_RELOAD_MS,
+                n, flags);
+    }
+
+    private CharSequence getTextBeforeCursorAndDetectLaggyConnection(
+            final int operation, final long timeout, final int n, final int flags) {
+        mIC = mParent.getCurrentInputConnection();
+        if (!isConnected()) {
+            return null;
+        }
+        final long startTime = SystemClock.uptimeMillis();
+        final CharSequence result = mIC.getTextBeforeCursor(n, flags);
+        detectLaggyConnection(operation, timeout, startTime);
+        return result;
+    }
+
+    public CharSequence getTextAfterCursor(final int n, final int flags) {
+        return getTextAfterCursorAndDetectLaggyConnection(
+                OPERATION_GET_TEXT_AFTER_CURSOR,
+                SLOW_INPUT_CONNECTION_ON_PARTIAL_RELOAD_MS,
+                n, flags);
+    }
+
+    private CharSequence getTextAfterCursorAndDetectLaggyConnection(
+            final int operation, final long timeout, final int n, final int flags) {
+        mIC = mParent.getCurrentInputConnection();
+        if (!isConnected()) {
+            return null;
+        }
+        final long startTime = SystemClock.uptimeMillis();
+        final CharSequence result = mIC.getTextAfterCursor(n, flags);
+        detectLaggyConnection(operation, timeout, startTime);
+        return result;
+    }
+
+    private void detectLaggyConnection(final int operation, final long timeout, final long startTime) {
+        final long duration = SystemClock.uptimeMillis() - startTime;
+        if (duration >= timeout) {
+            final String operationName = OPERATION_NAMES[operation];
+            Log.w(TAG, "Slow InputConnection: " + operationName + " took " + duration + " ms.");
+            StatsUtils.onInputConnectionLaggy(operation, duration);
+            mLastSlowInputConnectionTime = SystemClock.uptimeMillis();
+        }
+    }
+
+    public void deleteTextBeforeCursor(final int beforeLength) {
+        if (DEBUG_BATCH_NESTING) checkBatchEdit();
+        // TODO: the following is incorrect if the cursor is not immediately after the composition.
+        // Right now we never come here in this case because we reset the composing state before we
+        // come here in this case, but we need to fix this.
+        final int remainingChars = mComposingText.length() - beforeLength;
+        if (remainingChars >= 0) {
+            mComposingText.setLength(remainingChars);
+        } else {
+            mComposingText.setLength(0);
+            // Never cut under 0
+            final int len = Math.max(mCommittedTextBeforeComposingText.length()
+                    + remainingChars, 0);
+            mCommittedTextBeforeComposingText.setLength(len);
+        }
+        if (mExpectedSelStart > beforeLength) {
+            mExpectedSelStart -= beforeLength;
+            mExpectedSelEnd -= beforeLength;
+        } else {
+            // There are fewer characters before the cursor in the buffer than we are being asked to
+            // delete. Only delete what is there, and update the end with the amount deleted.
+            mExpectedSelEnd -= mExpectedSelStart;
+            mExpectedSelStart = 0;
+        }
+        if (isConnected()) {
+            mIC.deleteSurroundingText(beforeLength, 0);
+        }
+        if (DEBUG_PREVIOUS_TEXT) checkConsistencyForDebug();
+    }
+
+    public void performEditorAction(final int actionId) {
+        mIC = mParent.getCurrentInputConnection();
+        if (isConnected()) {
+            mIC.performEditorAction(actionId);
+        }
+    }
+
+    public void sendKeyEvent(final KeyEvent keyEvent) {
+        if (DEBUG_BATCH_NESTING) checkBatchEdit();
+        if (keyEvent.getAction() == KeyEvent.ACTION_DOWN) {
+            if (DEBUG_PREVIOUS_TEXT) checkConsistencyForDebug();
+            // This method is only called for enter or backspace when speaking to old applications
+            // (target SDK <= 15 (Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1)), or for digits.
+            // When talking to new applications we never use this method because it's inherently
+            // racy and has unpredictable results, but for backward compatibility we continue
+            // sending the key events for only Enter and Backspace because some applications
+            // mistakenly catch them to do some stuff.
+            switch (keyEvent.getKeyCode()) {
+            case KeyEvent.KEYCODE_ENTER:
+                mCommittedTextBeforeComposingText.append("\n");
+                mExpectedSelStart += 1;
+                mExpectedSelEnd = mExpectedSelStart;
+                break;
+            case KeyEvent.KEYCODE_DEL:
+                if (0 == mComposingText.length()) {
+                    if (mCommittedTextBeforeComposingText.length() > 0) {
+                        mCommittedTextBeforeComposingText.delete(
+                                mCommittedTextBeforeComposingText.length() - 1,
+                                mCommittedTextBeforeComposingText.length());
+                    }
+                } else {
+                    mComposingText.delete(mComposingText.length() - 1, mComposingText.length());
+                }
+                if (mExpectedSelStart > 0 && mExpectedSelStart == mExpectedSelEnd) {
+                    // TODO: Handle surrogate pairs.
+                    mExpectedSelStart -= 1;
+                }
+                mExpectedSelEnd = mExpectedSelStart;
+                break;
+            case KeyEvent.KEYCODE_UNKNOWN:
+                if (null != keyEvent.getCharacters()) {
+                    mCommittedTextBeforeComposingText.append(keyEvent.getCharacters());
+                    mExpectedSelStart += keyEvent.getCharacters().length();
+                    mExpectedSelEnd = mExpectedSelStart;
+                }
+                break;
+            default:
+                final String text = StringUtils.newSingleCodePointString(keyEvent.getUnicodeChar());
+                mCommittedTextBeforeComposingText.append(text);
+                mExpectedSelStart += text.length();
+                mExpectedSelEnd = mExpectedSelStart;
+                break;
+            }
+        }
+        if (isConnected()) {
+            mIC.sendKeyEvent(keyEvent);
+        }
+    }
+
+    public void setComposingRegion(final int start, final int end) {
+        if (DEBUG_BATCH_NESTING) checkBatchEdit();
+        if (DEBUG_PREVIOUS_TEXT) checkConsistencyForDebug();
+        final CharSequence textBeforeCursor =
+                getTextBeforeCursor(Constants.EDITOR_CONTENTS_CACHE_SIZE + (end - start), 0);
+        mCommittedTextBeforeComposingText.setLength(0);
+        if (!TextUtils.isEmpty(textBeforeCursor)) {
+            // The cursor is not necessarily at the end of the composing text, but we have its
+            // position in mExpectedSelStart and mExpectedSelEnd. In this case we want the start
+            // of the text, so we should use mExpectedSelStart. In other words, the composing
+            // text starts (mExpectedSelStart - start) characters before the end of textBeforeCursor
+            final int indexOfStartOfComposingText =
+                    Math.max(textBeforeCursor.length() - (mExpectedSelStart - start), 0);
+            mComposingText.append(textBeforeCursor.subSequence(indexOfStartOfComposingText,
+                    textBeforeCursor.length()));
+            mCommittedTextBeforeComposingText.append(
+                    textBeforeCursor.subSequence(0, indexOfStartOfComposingText));
+        }
+        if (isConnected()) {
+            mIC.setComposingRegion(start, end);
+        }
+    }
+
+    public void setComposingText(final CharSequence text, final int newCursorPosition) {
+        if (DEBUG_BATCH_NESTING) checkBatchEdit();
+        if (DEBUG_PREVIOUS_TEXT) checkConsistencyForDebug();
+        mExpectedSelStart += text.length() - mComposingText.length();
+        mExpectedSelEnd = mExpectedSelStart;
+        mComposingText.setLength(0);
+        mComposingText.append(text);
+        // TODO: support values of newCursorPosition != 1. At this time, this is never called with
+        // newCursorPosition != 1.
+        if (isConnected()) {
+            mIC.setComposingText(text, newCursorPosition);
+        }
+        if (DEBUG_PREVIOUS_TEXT) checkConsistencyForDebug();
+    }
+
+    /**
+     * Set the selection of the text editor.
+     *
+     * Calls through to {@link InputConnection#setSelection(int, int)}.
+     *
+     * @param start the character index where the selection should start.
+     * @param end the character index where the selection should end.
+     * @return Returns true on success, false on failure: either the input connection is no longer
+     * valid when setting the selection or when retrieving the text cache at that point, or
+     * invalid arguments were passed.
+     */
+    public boolean setSelection(final int start, final int end) {
+        if (DEBUG_BATCH_NESTING) checkBatchEdit();
+        if (DEBUG_PREVIOUS_TEXT) checkConsistencyForDebug();
+        if (start < 0 || end < 0) {
+            return false;
+        }
+        mExpectedSelStart = start;
+        mExpectedSelEnd = end;
+        if (isConnected()) {
+            final boolean isIcValid = mIC.setSelection(start, end);
+            if (!isIcValid) {
+                return false;
+            }
+        }
+        return reloadTextCache();
+    }
+
+    public void commitCorrection(final CorrectionInfo correctionInfo) {
+        if (DEBUG_BATCH_NESTING) checkBatchEdit();
+        if (DEBUG_PREVIOUS_TEXT) checkConsistencyForDebug();
+        // This has no effect on the text field and does not change its content. It only makes
+        // TextView flash the text for a second based on indices contained in the argument.
+        if (isConnected()) {
+            mIC.commitCorrection(correctionInfo);
+        }
+        if (DEBUG_PREVIOUS_TEXT) checkConsistencyForDebug();
+    }
+
+    public void commitCompletion(final CompletionInfo completionInfo) {
+        if (DEBUG_BATCH_NESTING) checkBatchEdit();
+        if (DEBUG_PREVIOUS_TEXT) checkConsistencyForDebug();
+        CharSequence text = completionInfo.getText();
+        // text should never be null, but just in case, it's better to insert nothing than to crash
+        if (null == text) text = "";
+        mCommittedTextBeforeComposingText.append(text);
+        mExpectedSelStart += text.length() - mComposingText.length();
+        mExpectedSelEnd = mExpectedSelStart;
+        mComposingText.setLength(0);
+        if (isConnected()) {
+            mIC.commitCompletion(completionInfo);
+        }
+        if (DEBUG_PREVIOUS_TEXT) checkConsistencyForDebug();
+    }
+
+    @SuppressWarnings("unused")
+    @Nonnull
+    public NgramContext getNgramContextFromNthPreviousWord(
+            final SpacingAndPunctuations spacingAndPunctuations, final int n) {
+        mIC = mParent.getCurrentInputConnection();
+        if (!isConnected()) {
+            return NgramContext.EMPTY_PREV_WORDS_INFO;
+        }
+        final CharSequence prev = getTextBeforeCursor(NUM_CHARS_TO_GET_BEFORE_CURSOR, 0);
+        if (DEBUG_PREVIOUS_TEXT && null != prev) {
+            final int checkLength = NUM_CHARS_TO_GET_BEFORE_CURSOR - 1;
+            final String reference = prev.length() <= checkLength ? prev.toString()
+                    : prev.subSequence(prev.length() - checkLength, prev.length()).toString();
+            // TODO: right now the following works because mComposingText holds the part of the
+            // composing text that is before the cursor, but this is very confusing. We should
+            // fix it.
+            final StringBuilder internal = new StringBuilder()
+                    .append(mCommittedTextBeforeComposingText).append(mComposingText);
+            if (internal.length() > checkLength) {
+                internal.delete(0, internal.length() - checkLength);
+                if (!(reference.equals(internal.toString()))) {
+                    final String context =
+                            "Expected text = " + internal + "\nActual text = " + reference;
+                    ((LatinIME)mParent).debugDumpStateAndCrashWithException(context);
+                }
+            }
+        }
+        return NgramContextUtils.getNgramContextFromNthPreviousWord(
+                prev, spacingAndPunctuations, n);
+    }
+
+    private static boolean isPartOfCompositionForScript(final int codePoint,
+            final SpacingAndPunctuations spacingAndPunctuations, final int scriptId) {
+        // We always consider word connectors part of compositions.
+        return spacingAndPunctuations.isWordConnector(codePoint)
+                // Otherwise, it's part of composition if it's part of script and not a separator.
+                || (!spacingAndPunctuations.isWordSeparator(codePoint)
+                        && ScriptUtils.isLetterPartOfScript(codePoint, scriptId));
+    }
+
+    /**
+     * Returns the text surrounding the cursor.
+     *
+     * @param spacingAndPunctuations the rules for spacing and punctuation
+     * @param scriptId the script we consider to be writing words, as one of ScriptUtils.SCRIPT_*
+     * @return a range containing the text surrounding the cursor
+     */
+    public TextRange getWordRangeAtCursor(final SpacingAndPunctuations spacingAndPunctuations,
+            final int scriptId) {
+        mIC = mParent.getCurrentInputConnection();
+        if (!isConnected()) {
+            return null;
+        }
+        final CharSequence before = getTextBeforeCursorAndDetectLaggyConnection(
+                OPERATION_GET_WORD_RANGE_AT_CURSOR,
+                SLOW_INPUT_CONNECTION_ON_PARTIAL_RELOAD_MS,
+                NUM_CHARS_TO_GET_BEFORE_CURSOR,
+                InputConnection.GET_TEXT_WITH_STYLES);
+        final CharSequence after = getTextAfterCursorAndDetectLaggyConnection(
+                OPERATION_GET_WORD_RANGE_AT_CURSOR,
+                SLOW_INPUT_CONNECTION_ON_PARTIAL_RELOAD_MS,
+                NUM_CHARS_TO_GET_AFTER_CURSOR,
+                InputConnection.GET_TEXT_WITH_STYLES);
+        if (before == null || after == null) {
+            return null;
+        }
+
+        // Going backward, find the first breaking point (separator)
+        int startIndexInBefore = before.length();
+        while (startIndexInBefore > 0) {
+            final int codePoint = Character.codePointBefore(before, startIndexInBefore);
+            if (!isPartOfCompositionForScript(codePoint, spacingAndPunctuations, scriptId)) {
+                break;
+            }
+            --startIndexInBefore;
+            if (Character.isSupplementaryCodePoint(codePoint)) {
+                --startIndexInBefore;
+            }
+        }
+
+        // Find last word separator after the cursor
+        int endIndexInAfter = -1;
+        while (++endIndexInAfter < after.length()) {
+            final int codePoint = Character.codePointAt(after, endIndexInAfter);
+            if (!isPartOfCompositionForScript(codePoint, spacingAndPunctuations, scriptId)) {
+                break;
+            }
+            if (Character.isSupplementaryCodePoint(codePoint)) {
+                ++endIndexInAfter;
+            }
+        }
+
+        final boolean hasUrlSpans =
+                SpannableStringUtils.hasUrlSpans(before, startIndexInBefore, before.length())
+                || SpannableStringUtils.hasUrlSpans(after, 0, endIndexInAfter);
+        // We don't use TextUtils#concat because it copies all spans without respect to their
+        // nature. If the text includes a PARAGRAPH span and it has been split, then
+        // TextUtils#concat will crash when it tries to concat both sides of it.
+        return new TextRange(
+                SpannableStringUtils.concatWithNonParagraphSuggestionSpansOnly(before, after),
+                        startIndexInBefore, before.length() + endIndexInAfter, before.length(),
+                        hasUrlSpans);
+    }
+
+    public boolean isCursorTouchingWord(final SpacingAndPunctuations spacingAndPunctuations,
+            boolean checkTextAfter) {
+        if (checkTextAfter && isCursorFollowedByWordCharacter(spacingAndPunctuations)) {
+            // If what's after the cursor is a word character, then we're touching a word.
+            return true;
+        }
+        final String textBeforeCursor = mCommittedTextBeforeComposingText.toString();
+        int indexOfCodePointInJavaChars = textBeforeCursor.length();
+        int consideredCodePoint = 0 == indexOfCodePointInJavaChars ? Constants.NOT_A_CODE
+                : textBeforeCursor.codePointBefore(indexOfCodePointInJavaChars);
+        // Search for the first non word-connector char
+        if (spacingAndPunctuations.isWordConnector(consideredCodePoint)) {
+            indexOfCodePointInJavaChars -= Character.charCount(consideredCodePoint);
+            consideredCodePoint = 0 == indexOfCodePointInJavaChars ? Constants.NOT_A_CODE
+                    : textBeforeCursor.codePointBefore(indexOfCodePointInJavaChars);
+        }
+        return !(Constants.NOT_A_CODE == consideredCodePoint
+                || spacingAndPunctuations.isWordSeparator(consideredCodePoint)
+                || spacingAndPunctuations.isWordConnector(consideredCodePoint));
+    }
+
+    public boolean isCursorFollowedByWordCharacter(
+            final SpacingAndPunctuations spacingAndPunctuations) {
+        final CharSequence after = getTextAfterCursor(1, 0);
+        if (TextUtils.isEmpty(after)) {
+            return false;
+        }
+        final int codePointAfterCursor = Character.codePointAt(after, 0);
+        if (spacingAndPunctuations.isWordSeparator(codePointAfterCursor)
+                || spacingAndPunctuations.isWordConnector(codePointAfterCursor)) {
+            return false;
+        }
+        return true;
+    }
+
+    public void removeTrailingSpace() {
+        if (DEBUG_BATCH_NESTING) checkBatchEdit();
+        final int codePointBeforeCursor = getCodePointBeforeCursor();
+        if (Constants.CODE_SPACE == codePointBeforeCursor) {
+            deleteTextBeforeCursor(1);
+        }
+    }
+
+    public boolean sameAsTextBeforeCursor(final CharSequence text) {
+        final CharSequence beforeText = getTextBeforeCursor(text.length(), 0);
+        return TextUtils.equals(text, beforeText);
+    }
+
+    public boolean revertDoubleSpacePeriod(final SpacingAndPunctuations spacingAndPunctuations) {
+        if (DEBUG_BATCH_NESTING) checkBatchEdit();
+        // Here we test whether we indeed have a period and a space before us. This should not
+        // be needed, but it's there just in case something went wrong.
+        final CharSequence textBeforeCursor = getTextBeforeCursor(2, 0);
+        if (!TextUtils.equals(spacingAndPunctuations.mSentenceSeparatorAndSpace,
+                textBeforeCursor)) {
+            // Theoretically we should not be coming here if there isn't ". " before the
+            // cursor, but the application may be changing the text while we are typing, so
+            // anything goes. We should not crash.
+            Log.d(TAG, "Tried to revert double-space combo but we didn't find \""
+                    + spacingAndPunctuations.mSentenceSeparatorAndSpace
+                    + "\" just before the cursor.");
+            return false;
+        }
+        // Double-space results in ". ". A backspace to cancel this should result in a single
+        // space in the text field, so we replace ". " with a single space.
+        deleteTextBeforeCursor(2);
+        final String singleSpace = " ";
+        commitText(singleSpace, 1);
+        return true;
+    }
+
+    public boolean revertSwapPunctuation() {
+        if (DEBUG_BATCH_NESTING) checkBatchEdit();
+        // Here we test whether we indeed have a space and something else before us. This should not
+        // be needed, but it's there just in case something went wrong.
+        final CharSequence textBeforeCursor = getTextBeforeCursor(2, 0);
+        // NOTE: This does not work with surrogate pairs. Hopefully when the keyboard is able to
+        // enter surrogate pairs this code will have been removed.
+        if (TextUtils.isEmpty(textBeforeCursor)
+                || (Constants.CODE_SPACE != textBeforeCursor.charAt(1))) {
+            // We may only come here if the application is changing the text while we are typing.
+            // This is quite a broken case, but not logically impossible, so we shouldn't crash,
+            // but some debugging log may be in order.
+            Log.d(TAG, "Tried to revert a swap of punctuation but we didn't "
+                    + "find a space just before the cursor.");
+            return false;
+        }
+        deleteTextBeforeCursor(2);
+        final String text = " " + textBeforeCursor.subSequence(0, 1);
+        commitText(text, 1);
+        return true;
+    }
+
+    /**
+     * Heuristic to determine if this is an expected update of the cursor.
+     *
+     * Sometimes updates to the cursor position are late because of their asynchronous nature.
+     * This method tries to determine if this update is one, based on the values of the cursor
+     * position in the update, and the currently expected position of the cursor according to
+     * LatinIME's internal accounting. If this is not a belated expected update, then it should
+     * mean that the user moved the cursor explicitly.
+     * This is quite robust, but of course it's not perfect. In particular, it will fail in the
+     * case we get an update A, the user types in N characters so as to move the cursor to A+N but
+     * we don't get those, and then the user places the cursor between A and A+N, and we get only
+     * this update and not the ones in-between. This is almost impossible to achieve even trying
+     * very very hard.
+     *
+     * @param oldSelStart The value of the old selection in the update.
+     * @param newSelStart The value of the new selection in the update.
+     * @param oldSelEnd The value of the old selection end in the update.
+     * @param newSelEnd The value of the new selection end in the update.
+     * @return whether this is a belated expected update or not.
+     */
+    public boolean isBelatedExpectedUpdate(final int oldSelStart, final int newSelStart,
+            final int oldSelEnd, final int newSelEnd) {
+        // This update is "belated" if we are expecting it. That is, mExpectedSelStart and
+        // mExpectedSelEnd match the new values that the TextView is updating TO.
+        if (mExpectedSelStart == newSelStart && mExpectedSelEnd == newSelEnd) return true;
+        // This update is not belated if mExpectedSelStart and mExpectedSelEnd match the old
+        // values, and one of newSelStart or newSelEnd is updated to a different value. In this
+        // case, it is likely that something other than the IME has moved the selection endpoint
+        // to the new value.
+        if (mExpectedSelStart == oldSelStart && mExpectedSelEnd == oldSelEnd
+                && (oldSelStart != newSelStart || oldSelEnd != newSelEnd)) return false;
+        // If neither of the above two cases hold, then the system may be having trouble keeping up
+        // with updates. If 1) the selection is a cursor, 2) newSelStart is between oldSelStart
+        // and mExpectedSelStart, and 3) newSelEnd is between oldSelEnd and mExpectedSelEnd, then
+        // assume a belated update.
+        return (newSelStart == newSelEnd)
+                && (newSelStart - oldSelStart) * (mExpectedSelStart - newSelStart) >= 0
+                && (newSelEnd - oldSelEnd) * (mExpectedSelEnd - newSelEnd) >= 0;
+    }
+
+    /**
+     * Looks at the text just before the cursor to find out if it looks like a URL.
+     *
+     * The weakest point here is, if we don't have enough text bufferized, we may fail to realize
+     * we are in URL situation, but other places in this class have the same limitation and it
+     * does not matter too much in the practice.
+     */
+    public boolean textBeforeCursorLooksLikeURL() {
+        return StringUtils.lastPartLooksLikeURL(mCommittedTextBeforeComposingText);
+    }
+
+    /**
+     * Looks at the text just before the cursor to find out if we are inside a double quote.
+     *
+     * As with #textBeforeCursorLooksLikeURL, this is dependent on how much text we have cached.
+     * However this won't be a concrete problem in most situations, as the cache is almost always
+     * long enough for this use.
+     */
+    public boolean isInsideDoubleQuoteOrAfterDigit() {
+        return StringUtils.isInsideDoubleQuoteOrAfterDigit(mCommittedTextBeforeComposingText);
+    }
+
+    /**
+     * Try to get the text from the editor to expose lies the framework may have been
+     * telling us. Concretely, when the device rotates and when the keyboard reopens in the same
+     * text field after having been closed with the back key, the frameworks tells us about where
+     * the cursor used to be initially in the editor at the time it first received the focus; this
+     * may be completely different from the place it is upon rotation. Since we don't have any
+     * means to get the real value, try at least to ask the text view for some characters and
+     * detect the most damaging cases: when the cursor position is declared to be much smaller
+     * than it really is.
+     */
+    public void tryFixLyingCursorPosition() {
+        mIC = mParent.getCurrentInputConnection();
+        final CharSequence textBeforeCursor = getTextBeforeCursor(
+                Constants.EDITOR_CONTENTS_CACHE_SIZE, 0);
+        final CharSequence selectedText = isConnected() ? mIC.getSelectedText(0 /* flags */) : null;
+        if (null == textBeforeCursor ||
+                (!TextUtils.isEmpty(selectedText) && mExpectedSelEnd == mExpectedSelStart)) {
+            // If textBeforeCursor is null, we have no idea what kind of text field we have or if
+            // thinking about the "cursor position" actually makes any sense. In this case we
+            // remember a meaningless cursor position. Contrast this with an empty string, which is
+            // valid and should mean the cursor is at the start of the text.
+            // Also, if we expect we don't have a selection but we DO have non-empty selected text,
+            // then the framework lied to us about the cursor position. In this case, we should just
+            // revert to the most basic behavior possible for the next action (backspace in
+            // particular comes to mind), so we remember a meaningless cursor position which should
+            // result in degraded behavior from the next input.
+            // Interestingly, in either case, chances are any action the user takes next will result
+            // in a call to onUpdateSelection, which should set things right.
+            mExpectedSelStart = mExpectedSelEnd = Constants.NOT_A_CURSOR_POSITION;
+        } else {
+            final int textLength = textBeforeCursor.length();
+            if (textLength < Constants.EDITOR_CONTENTS_CACHE_SIZE
+                    && (textLength > mExpectedSelStart
+                            ||  mExpectedSelStart < Constants.EDITOR_CONTENTS_CACHE_SIZE)) {
+                // It should not be possible to have only one of those variables be
+                // NOT_A_CURSOR_POSITION, so if they are equal, either the selection is zero-sized
+                // (simple cursor, no selection) or there is no cursor/we don't know its pos
+                final boolean wasEqual = mExpectedSelStart == mExpectedSelEnd;
+                mExpectedSelStart = textLength;
+                // We can't figure out the value of mLastSelectionEnd :(
+                // But at least if it's smaller than mLastSelectionStart something is wrong,
+                // and if they used to be equal we also don't want to make it look like there is a
+                // selection.
+                if (wasEqual || mExpectedSelStart > mExpectedSelEnd) {
+                    mExpectedSelEnd = mExpectedSelStart;
+                }
+            }
+        }
+    }
+
+    @Override
+    public boolean performPrivateCommand(final String action, final Bundle data) {
+        mIC = mParent.getCurrentInputConnection();
+        if (!isConnected()) {
+            return false;
+        }
+        return mIC.performPrivateCommand(action, data);
+    }
+
+    public int getExpectedSelectionStart() {
+        return mExpectedSelStart;
+    }
+
+    public int getExpectedSelectionEnd() {
+        return mExpectedSelEnd;
+    }
+
+    /**
+     * @return whether there is a selection currently active.
+     */
+    public boolean hasSelection() {
+        return mExpectedSelEnd != mExpectedSelStart;
+    }
+
+    public boolean isCursorPositionKnown() {
+        return INVALID_CURSOR_POSITION != mExpectedSelStart;
+    }
+
+    /**
+     * Work around a bug that was present before Jelly Bean upon rotation.
+     *
+     * Before Jelly Bean, there is a bug where setComposingRegion and other committing
+     * functions on the input connection get ignored until the cursor moves. This method works
+     * around the bug by wiggling the cursor first, which reactivates the connection and has
+     * the subsequent methods work, then restoring it to its original position.
+     *
+     * On platforms on which this method is not present, this is a no-op.
+     */
+    public void maybeMoveTheCursorAroundAndRestoreToWorkaroundABug() {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
+            if (mExpectedSelStart > 0) {
+                mIC.setSelection(mExpectedSelStart - 1, mExpectedSelStart - 1);
+            } else {
+                mIC.setSelection(mExpectedSelStart + 1, mExpectedSelStart + 1);
+            }
+            mIC.setSelection(mExpectedSelStart, mExpectedSelEnd);
+        }
+    }
+
+    /**
+     * Requests the editor to call back {@link InputMethodManager#updateCursorAnchorInfo}.
+     * @param enableMonitor {@code true} to request the editor to call back the method whenever the
+     * cursor/anchor position is changed.
+     * @param requestImmediateCallback {@code true} to request the editor to call back the method
+     * as soon as possible to notify the current cursor/anchor position to the input method.
+     * @return {@code true} if the request is accepted. Returns {@code false} otherwise, which
+     * includes "not implemented" or "rejected" or "temporarily unavailable" or whatever which
+     * prevents the application from fulfilling the request. (TODO: Improve the API when it turns
+     * out that we actually need more detailed error codes)
+     */
+    public boolean requestCursorUpdates(final boolean enableMonitor,
+            final boolean requestImmediateCallback) {
+        mIC = mParent.getCurrentInputConnection();
+        if (!isConnected()) {
+            return false;
+        }
+        return InputConnectionCompatUtils.requestCursorUpdates(
+                mIC, enableMonitor, requestImmediateCallback);
+    }
+}