1 files changed, 137 insertions, 0 deletions
diff --git a/java/src/org/kelar/inputmethod/event/CombinerChain.java b/java/src/org/kelar/inputmethod/event/CombinerChain.java
new file mode 100644
index 000000000..afd992e62
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+++ b/java/src/org/kelar/inputmethod/event/CombinerChain.java
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+/*
+ * Copyright (C) 2014 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.event;
+
+import android.text.SpannableStringBuilder;
+import android.text.TextUtils;
+
+import org.kelar.inputmethod.latin.common.Constants;
+
+import java.util.ArrayList;
+
+import javax.annotation.Nonnull;
+
+/**
+ * This class implements the logic chain between receiving events and generating code points.
+ *
+ * Event sources are multiple. It may be a hardware keyboard, a D-PAD, a software keyboard,
+ * or any exotic input source.
+ * This class will orchestrate the composing chain that starts with an event as its input. Each
+ * composer will be given turns one after the other.
+ * The output is composed of two sequences of code points: the first, representing the already
+ * finished combining part, will be shown normally as the composing string, while the second is
+ * feedback on the composing state and will typically be shown with different styling such as
+ * a colored background.
+ */
+public class CombinerChain {
+    // The already combined text, as described above
+    private StringBuilder mCombinedText;
+    // The feedback on the composing state, as described above
+    private SpannableStringBuilder mStateFeedback;
+    private final ArrayList<Combiner> mCombiners;
+
+    /**
+     * Create an combiner chain.
+     *
+     * The combiner chain takes events as inputs and outputs code points and combining state.
+     * For example, if the input language is Japanese, the combining chain will typically perform
+     * kana conversion. This takes a string for initial text, taken to be present before the
+     * cursor: we'll start after this.
+     *
+     * @param initialText The text that has already been combined so far.
+     */
+    public CombinerChain(final String initialText) {
+        mCombiners = new ArrayList<>();
+        // The dead key combiner is always active, and always first
+        mCombiners.add(new DeadKeyCombiner());
+        mCombinedText = new StringBuilder(initialText);
+        mStateFeedback = new SpannableStringBuilder();
+    }
+
+    public void reset() {
+        mCombinedText.setLength(0);
+        mStateFeedback.clear();
+        for (final Combiner c : mCombiners) {
+            c.reset();
+        }
+    }
+
+    private void updateStateFeedback() {
+        mStateFeedback.clear();
+        for (int i = mCombiners.size() - 1; i >= 0; --i) {
+            mStateFeedback.append(mCombiners.get(i).getCombiningStateFeedback());
+        }
+    }
+
+    /**
+     * Process an event through the combining chain, and return a processed event to apply.
+     * @param previousEvents the list of previous events in this composition
+     * @param newEvent the new event to process
+     * @return the processed event. It may be the same event, or a consumed event, or a completely
+     *   new event. However it may never be null.
+     */
+    @Nonnull
+    public Event processEvent(final ArrayList<Event> previousEvents,
+            @Nonnull final Event newEvent) {
+        final ArrayList<Event> modifiablePreviousEvents = new ArrayList<>(previousEvents);
+        Event event = newEvent;
+        for (final Combiner combiner : mCombiners) {
+            // A combiner can never return more than one event; it can return several
+            // code points, but they should be encapsulated within one event.
+            event = combiner.processEvent(modifiablePreviousEvents, event);
+            if (event.isConsumed()) {
+                // If the event is consumed, then we don't pass it to subsequent combiners:
+                // they should not see it at all.
+                break;
+            }
+        }
+        updateStateFeedback();
+        return event;
+    }
+
+    /**
+     * Apply a processed event.
+     * @param event the event to be applied
+     */
+    public void applyProcessedEvent(final Event event) {
+        if (null != event) {
+            // TODO: figure out the generic way of doing this
+            if (Constants.CODE_DELETE == event.mKeyCode) {
+                final int length = mCombinedText.length();
+                if (length > 0) {
+                    final int lastCodePoint = mCombinedText.codePointBefore(length);
+                    mCombinedText.delete(length - Character.charCount(lastCodePoint), length);
+                }
+            } else {
+                final CharSequence textToCommit = event.getTextToCommit();
+                if (!TextUtils.isEmpty(textToCommit)) {
+                    mCombinedText.append(textToCommit);
+                }
+            }
+        }
+        updateStateFeedback();
+    }
+
+    /**
+     * Get the char sequence that should be displayed as the composing word. It may include
+     * styling spans.
+     */
+    public CharSequence getComposingWordWithCombiningFeedback() {
+        final SpannableStringBuilder s = new SpannableStringBuilder(mCombinedText);
+        return s.append(mStateFeedback);
+    }
+}