Add SparseTable.

Bug: 10920165
Change-Id: I749dd0269e788799e30b10beb2671813d40ce15f

2 files changed, 170 insertions, 0 deletions

diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoderUtils.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoderUtils.java
index 3b1d2427b..6cc0bfb76 100644
--- a/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoderUtils.java
+++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoderUtils.java
@@ -225,6 +225,26 @@ public class BinaryDictEncoderUtils {
         return position;
     }
 
+    static void writeUIntToStream(final OutputStream stream, final int value, final int size)
+            throws IOException {
+        switch(size) {
+            case 4:
+                stream.write((value >> 24) & 0xFF);
+                /* fall through */
+            case 3:
+                stream.write((value >> 16) & 0xFF);
+                /* fall through */
+            case 2:
+                stream.write((value >> 8) & 0xFF);
+                /* fall through */
+            case 1:
+                stream.write(value & 0xFF);
+                break;
+            default:
+                /* nop */
+        }
+    }
+
     // End utility methods
 
     // This method is responsible for finding a nice ordering of the nodes that favors run-time
diff --git a/java/src/com/android/inputmethod/latin/makedict/SparseTable.java b/java/src/com/android/inputmethod/latin/makedict/SparseTable.java
new file mode 100644
index 000000000..0b9cf91d2
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/makedict/SparseTable.java
@@ -0,0 +1,150 @@
+/*
+ * 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.makedict;
+
+import com.android.inputmethod.annotations.UsedForTesting;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.ArrayList;
+import java.util.Collections;
+
+/**
+ * SparseTable is an extensible map from integer to integer.
+ * This holds one value for every mBlockSize keys, so it uses 1/mBlockSize'th of the full index
+ * memory.
+ */
+@UsedForTesting
+public class SparseTable {
+
+    /**
+     * mLookupTable is indexed by terminal ID, containing exactly one entry for every mBlockSize
+     * terminals.
+     * It contains at index i = j / mBlockSize the index in mContentsTable where the values for
+     * terminals with IDs j to j + mBlockSize - 1 are stored as an mBlockSize-sized integer array.
+     */
+    private final ArrayList<Integer> mLookupTable;
+    private final ArrayList<Integer> mContentTable;
+
+    private final int mBlockSize;
+    public static final int NOT_EXIST = -1;
+
+    @UsedForTesting
+    public SparseTable(final int initialCapacity, final int blockSize) {
+        mBlockSize = blockSize;
+        final int lookupTableSize = initialCapacity / mBlockSize
+                + (initialCapacity % mBlockSize > 0 ? 1 : 0);
+        mLookupTable = new ArrayList<Integer>(Collections.nCopies(lookupTableSize, NOT_EXIST));
+        mContentTable = new ArrayList<Integer>();
+    }
+
+    @UsedForTesting
+    public SparseTable(final int[] lookupTable, final int[] contentTable, final int blockSize) {
+        mBlockSize = blockSize;
+        mLookupTable = new ArrayList<Integer>(lookupTable.length);
+        for (int i = 0; i < lookupTable.length; ++i) {
+            mLookupTable.add(lookupTable[i]);
+        }
+        mContentTable = new ArrayList<Integer>(contentTable.length);
+        for (int i = 0; i < contentTable.length; ++i) {
+            mContentTable.add(contentTable[i]);
+        }
+    }
+
+    /**
+     * Converts an byte array to an int array considering each set of 4 bytes is an int stored in
+     * big-endian.
+     * The length of byteArray must be a multiple of four.
+     * Otherwise, IndexOutOfBoundsException will be raised.
+     */
+    @UsedForTesting
+    private static void convertByteArrayToIntegerArray(final byte[] byteArray,
+            final ArrayList<Integer> integerArray) {
+        for (int i = 0; i < byteArray.length; i += 4) {
+            int value = 0;
+            for (int j = i; j < i + 4; ++j) {
+                value <<= 8;
+                value |= byteArray[j] & 0xFF;
+             }
+            integerArray.add(value);
+        }
+    }
+
+    @UsedForTesting
+    public SparseTable(final byte[] lookupTable, final byte[] contentTable, final int blockSize) {
+        mBlockSize = blockSize;
+        mLookupTable = new ArrayList<Integer>(lookupTable.length / 4);
+        mContentTable = new ArrayList<Integer>(contentTable.length / 4);
+        convertByteArrayToIntegerArray(lookupTable, mLookupTable);
+        convertByteArrayToIntegerArray(contentTable, mContentTable);
+    }
+
+    @UsedForTesting
+    public int get(final int index) {
+        if (index < 0 || index / mBlockSize >= mLookupTable.size()
+                || mLookupTable.get(index / mBlockSize) == NOT_EXIST) {
+            return NOT_EXIST;
+        }
+        return mContentTable.get(mLookupTable.get(index / mBlockSize) + (index % mBlockSize));
+    }
+
+    @UsedForTesting
+    public void set(final int index, final int value) {
+        if (mLookupTable.get(index / mBlockSize) == NOT_EXIST) {
+            mLookupTable.set(index / mBlockSize, mContentTable.size());
+            for (int i = 0; i < mBlockSize; ++i) {
+                mContentTable.add(NOT_EXIST);
+            }
+        }
+        mContentTable.set(mLookupTable.get(index / mBlockSize) + (index % mBlockSize), value);
+    }
+
+    public void remove(final int index) {
+        set(index, NOT_EXIST);
+    }
+
+    @UsedForTesting
+    public int size() {
+        return mLookupTable.size() * mBlockSize;
+    }
+
+    @UsedForTesting
+    /* package */ int getContentTableSize() {
+        return mContentTable.size();
+    }
+
+    @UsedForTesting
+    /* package */ int getLookupTableSize() {
+        return mLookupTable.size();
+    }
+
+    public boolean contains(final int index) {
+        return get(index) != NOT_EXIST;
+    }
+
+    @UsedForTesting
+    public void write(final OutputStream lookupOutStream, final OutputStream contentOutStream)
+            throws IOException {
+        for (final int index : mLookupTable) {
+          BinaryDictEncoderUtils.writeUIntToStream(lookupOutStream, index, 4);
+        }
+
+        for (final int index : mContentTable) {
+            BinaryDictEncoderUtils.writeUIntToStream(contentOutStream, index, 4);
+        }
+    }
+}