Rename BinaryDictEncoder to BinaryDictEncoderUtils.

Change-Id: I4dabf17da7003b1d8204a83dbd10e5be6e8fd805

1 files changed, 0 insertions, 1006 deletions

diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoder.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoder.java
deleted file mode 100644
index ff11cde39..000000000
--- a/java/src/com/android/inputmethod/latin/makedict/BinaryDictEncoder.java
+++ /dev/null
@@ -1,1006 +0,0 @@
-/*
- * 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.latin.makedict.BinaryDictDecoderUtils.CharEncoding;
-import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions;
-import com.android.inputmethod.latin.makedict.FusionDictionary.CharGroup;
-import com.android.inputmethod.latin.makedict.FusionDictionary.DictionaryOptions;
-import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
-import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
-
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
-import java.io.OutputStream;
-import java.util.ArrayList;
-import java.util.Iterator;
-
-/**
- * Encodes binary files for a FusionDictionary.
- *
- * All the methods in this class are static.
- */
-public class BinaryDictEncoder {
-
-    private static final boolean DBG = MakedictLog.DBG;
-
-    private BinaryDictEncoder() {
-        // This utility class is not publicly instantiable.
-    }
-
-    // Arbitrary limit to how much passes we consider address size compression should
-    // terminate in. At the time of this writing, our largest dictionary completes
-    // compression in five passes.
-    // If the number of passes exceeds this number, makedict bails with an exception on
-    // suspicion that a bug might be causing an infinite loop.
-    private static final int MAX_PASSES = 24;
-
-    /**
-     * Compute the binary size of the character array.
-     *
-     * If only one character, this is the size of this character. If many, it's the sum of their
-     * sizes + 1 byte for the terminator.
-     *
-     * @param characters the character array
-     * @return the size of the char array, including the terminator if any
-     */
-    static int getGroupCharactersSize(final int[] characters) {
-        int size = CharEncoding.getCharArraySize(characters);
-        if (characters.length > 1) size += FormatSpec.GROUP_TERMINATOR_SIZE;
-        return size;
-    }
-
-    /**
-     * Compute the binary size of the character array in a group
-     *
-     * If only one character, this is the size of this character. If many, it's the sum of their
-     * sizes + 1 byte for the terminator.
-     *
-     * @param group the group
-     * @return the size of the char array, including the terminator if any
-     */
-    private static int getGroupCharactersSize(final CharGroup group) {
-        return getGroupCharactersSize(group.mChars);
-    }
-
-    /**
-     * Compute the binary size of the group count for a node array.
-     * @param nodeArray the nodeArray
-     * @return the size of the group count, either 1 or 2 bytes.
-     */
-    private static int getGroupCountSize(final PtNodeArray nodeArray) {
-        return BinaryDictIOUtils.getGroupCountSize(nodeArray.mData.size());
-    }
-
-    /**
-     * Compute the size of a shortcut in bytes.
-     */
-    private static int getShortcutSize(final WeightedString shortcut) {
-        int size = FormatSpec.GROUP_ATTRIBUTE_FLAGS_SIZE;
-        final String word = shortcut.mWord;
-        final int length = word.length();
-        for (int i = 0; i < length; i = word.offsetByCodePoints(i, 1)) {
-            final int codePoint = word.codePointAt(i);
-            size += CharEncoding.getCharSize(codePoint);
-        }
-        size += FormatSpec.GROUP_TERMINATOR_SIZE;
-        return size;
-    }
-
-    /**
-     * Compute the size of a shortcut list in bytes.
-     *
-     * This is known in advance and does not change according to position in the file
-     * like address lists do.
-     */
-    static int getShortcutListSize(final ArrayList<WeightedString> shortcutList) {
-        if (null == shortcutList) return 0;
-        int size = FormatSpec.GROUP_SHORTCUT_LIST_SIZE_SIZE;
-        for (final WeightedString shortcut : shortcutList) {
-            size += getShortcutSize(shortcut);
-        }
-        return size;
-    }
-
-    /**
-     * Compute the maximum size of a CharGroup, assuming 3-byte addresses for everything.
-     *
-     * @param group the CharGroup to compute the size of.
-     * @param options file format options.
-     * @return the maximum size of the group.
-     */
-    private static int getCharGroupMaximumSize(final CharGroup group, final FormatOptions options) {
-        int size = getGroupHeaderSize(group, options);
-        // If terminal, one byte for the frequency
-        if (group.isTerminal()) size += FormatSpec.GROUP_FREQUENCY_SIZE;
-        size += FormatSpec.GROUP_MAX_ADDRESS_SIZE; // For children address
-        size += getShortcutListSize(group.mShortcutTargets);
-        if (null != group.mBigrams) {
-            size += (FormatSpec.GROUP_ATTRIBUTE_FLAGS_SIZE
-                    + FormatSpec.GROUP_ATTRIBUTE_MAX_ADDRESS_SIZE)
-                    * group.mBigrams.size();
-        }
-        return size;
-    }
-
-    /**
-     * Compute the maximum size of each node of a node array, assuming 3-byte addresses for
-     * everything, and caches it in the `mCachedSize' member of the nodes; deduce the size of
-     * the containing node array, and cache it it its 'mCachedSize' member.
-     *
-     * @param nodeArray the node array to compute the maximum size of.
-     * @param options file format options.
-     */
-    private static void calculateNodeArrayMaximumSize(final PtNodeArray nodeArray,
-            final FormatOptions options) {
-        int size = getGroupCountSize(nodeArray);
-        for (CharGroup g : nodeArray.mData) {
-            final int groupSize = getCharGroupMaximumSize(g, options);
-            g.mCachedSize = groupSize;
-            size += groupSize;
-        }
-        if (options.mSupportsDynamicUpdate) {
-            size += FormatSpec.FORWARD_LINK_ADDRESS_SIZE;
-        }
-        nodeArray.mCachedSize = size;
-    }
-
-    /**
-     * Compute the size of the header (flag + [parent address] + characters size) of a CharGroup.
-     *
-     * @param group the group of which to compute the size of the header
-     * @param options file format options.
-     */
-    private static int getGroupHeaderSize(final CharGroup group, final FormatOptions options) {
-        if (BinaryDictIOUtils.supportsDynamicUpdate(options)) {
-            return FormatSpec.GROUP_FLAGS_SIZE + FormatSpec.PARENT_ADDRESS_SIZE
-                    + getGroupCharactersSize(group);
-        } else {
-            return FormatSpec.GROUP_FLAGS_SIZE + getGroupCharactersSize(group);
-        }
-    }
-
-    /**
-     * Compute the size, in bytes, that an address will occupy.
-     *
-     * This can be used either for children addresses (which are always positive) or for
-     * attribute, which may be positive or negative but
-     * store their sign bit separately.
-     *
-     * @param address the address
-     * @return the byte size.
-     */
-    static int getByteSize(final int address) {
-        assert(address <= FormatSpec.UINT24_MAX);
-        if (!BinaryDictIOUtils.hasChildrenAddress(address)) {
-            return 0;
-        } else if (Math.abs(address) <= FormatSpec.UINT8_MAX) {
-            return 1;
-        } else if (Math.abs(address) <= FormatSpec.UINT16_MAX) {
-            return 2;
-        } else {
-            return 3;
-        }
-    }
-
-    // End utility methods
-
-    // This method is responsible for finding a nice ordering of the nodes that favors run-time
-    // cache performance and dictionary size.
-    /* package for tests */ static ArrayList<PtNodeArray> flattenTree(
-            final PtNodeArray rootNodeArray) {
-        final int treeSize = FusionDictionary.countCharGroups(rootNodeArray);
-        MakedictLog.i("Counted nodes : " + treeSize);
-        final ArrayList<PtNodeArray> flatTree = new ArrayList<PtNodeArray>(treeSize);
-        return flattenTreeInner(flatTree, rootNodeArray);
-    }
-
-    private static ArrayList<PtNodeArray> flattenTreeInner(final ArrayList<PtNodeArray> list,
-            final PtNodeArray nodeArray) {
-        // Removing the node is necessary if the tails are merged, because we would then
-        // add the same node several times when we only want it once. A number of places in
-        // the code also depends on any node being only once in the list.
-        // Merging tails can only be done if there are no attributes. Searching for attributes
-        // in LatinIME code depends on a total breadth-first ordering, which merging tails
-        // breaks. If there are no attributes, it should be fine (and reduce the file size)
-        // to merge tails, and removing the node from the list would be necessary. However,
-        // we don't merge tails because breaking the breadth-first ordering would result in
-        // extreme overhead at bigram lookup time (it would make the search function O(n) instead
-        // of the current O(log(n)), where n=number of nodes in the dictionary which is pretty
-        // high).
-        // If no nodes are ever merged, we can't have the same node twice in the list, hence
-        // searching for duplicates in unnecessary. It is also very performance consuming,
-        // since `list' is an ArrayList so it's an O(n) operation that runs on all nodes, making
-        // this simple list.remove operation O(n*n) overall. On Android this overhead is very
-        // high.
-        // For future reference, the code to remove duplicate is a simple : list.remove(node);
-        list.add(nodeArray);
-        final ArrayList<CharGroup> branches = nodeArray.mData;
-        final int nodeSize = branches.size();
-        for (CharGroup group : branches) {
-            if (null != group.mChildren) flattenTreeInner(list, group.mChildren);
-        }
-        return list;
-    }
-
-    /**
-     * Get the offset from a position inside a current node array to a target node array, during
-     * update.
-     *
-     * If the current node array is before the target node array, the target node array has not
-     * been updated yet, so we should return the offset from the old position of the current node
-     * array to the old position of the target node array. If on the other hand the target is
-     * before the current node array, it already has been updated, so we should return the offset
-     * from the new position in the current node array to the new position in the target node
-     * array.
-     *
-     * @param currentNodeArray node array containing the CharGroup where the offset will be written
-     * @param offsetFromStartOfCurrentNodeArray offset, in bytes, from the start of currentNodeArray
-     * @param targetNodeArray the target node array to get the offset to
-     * @return the offset to the target node array
-     */
-    private static int getOffsetToTargetNodeArrayDuringUpdate(final PtNodeArray currentNodeArray,
-            final int offsetFromStartOfCurrentNodeArray, final PtNodeArray targetNodeArray) {
-        final boolean isTargetBeforeCurrent = (targetNodeArray.mCachedAddressBeforeUpdate
-                < currentNodeArray.mCachedAddressBeforeUpdate);
-        if (isTargetBeforeCurrent) {
-            return targetNodeArray.mCachedAddressAfterUpdate
-                    - (currentNodeArray.mCachedAddressAfterUpdate
-                            + offsetFromStartOfCurrentNodeArray);
-        } else {
-            return targetNodeArray.mCachedAddressBeforeUpdate
-                    - (currentNodeArray.mCachedAddressBeforeUpdate
-                            + offsetFromStartOfCurrentNodeArray);
-        }
-    }
-
-    /**
-     * Get the offset from a position inside a current node array to a target CharGroup, during
-     * update.
-     *
-     * @param currentNodeArray node array containing the CharGroup where the offset will be written
-     * @param offsetFromStartOfCurrentNodeArray offset, in bytes, from the start of currentNodeArray
-     * @param targetCharGroup the target CharGroup to get the offset to
-     * @return the offset to the target CharGroup
-     */
-    // TODO: is there any way to factorize this method with the one above?
-    private static int getOffsetToTargetCharGroupDuringUpdate(final PtNodeArray currentNodeArray,
-            final int offsetFromStartOfCurrentNodeArray, final CharGroup targetCharGroup) {
-        final int oldOffsetBasePoint = currentNodeArray.mCachedAddressBeforeUpdate
-                + offsetFromStartOfCurrentNodeArray;
-        final boolean isTargetBeforeCurrent = (targetCharGroup.mCachedAddressBeforeUpdate
-                < oldOffsetBasePoint);
-        // If the target is before the current node array, then its address has already been
-        // updated. We can use the AfterUpdate member, and compare it to our own member after
-        // update. Otherwise, the AfterUpdate member is not updated yet, so we need to use the
-        // BeforeUpdate member, and of course we have to compare this to our own address before
-        // update.
-        if (isTargetBeforeCurrent) {
-            final int newOffsetBasePoint = currentNodeArray.mCachedAddressAfterUpdate
-                    + offsetFromStartOfCurrentNodeArray;
-            return targetCharGroup.mCachedAddressAfterUpdate - newOffsetBasePoint;
-        } else {
-            return targetCharGroup.mCachedAddressBeforeUpdate - oldOffsetBasePoint;
-        }
-    }
-
-    /**
-     * Computes the actual node array size, based on the cached addresses of the children nodes.
-     *
-     * Each node array stores its tentative address. During dictionary address computing, these
-     * are not final, but they can be used to compute the node array size (the node array size
-     * depends on the address of the children because the number of bytes necessary to store an
-     * address depends on its numeric value. The return value indicates whether the node array
-     * contents (as in, any of the addresses stored in the cache fields) have changed with
-     * respect to their previous value.
-     *
-     * @param nodeArray the node array to compute the size of.
-     * @param dict the dictionary in which the word/attributes are to be found.
-     * @param formatOptions file format options.
-     * @return false if none of the cached addresses inside the node array changed, true otherwise.
-     */
-    private static boolean computeActualNodeArraySize(final PtNodeArray nodeArray,
-            final FusionDictionary dict, final FormatOptions formatOptions) {
-        boolean changed = false;
-        int size = getGroupCountSize(nodeArray);
-        for (CharGroup group : nodeArray.mData) {
-            group.mCachedAddressAfterUpdate = nodeArray.mCachedAddressAfterUpdate + size;
-            if (group.mCachedAddressAfterUpdate != group.mCachedAddressBeforeUpdate) {
-                changed = true;
-            }
-            int groupSize = getGroupHeaderSize(group, formatOptions);
-            if (group.isTerminal()) groupSize += FormatSpec.GROUP_FREQUENCY_SIZE;
-            if (null == group.mChildren && formatOptions.mSupportsDynamicUpdate) {
-                groupSize += FormatSpec.SIGNED_CHILDREN_ADDRESS_SIZE;
-            } else if (null != group.mChildren) {
-                if (formatOptions.mSupportsDynamicUpdate) {
-                    groupSize += FormatSpec.SIGNED_CHILDREN_ADDRESS_SIZE;
-                } else {
-                    groupSize += getByteSize(getOffsetToTargetNodeArrayDuringUpdate(nodeArray,
-                            groupSize + size, group.mChildren));
-                }
-            }
-            groupSize += getShortcutListSize(group.mShortcutTargets);
-            if (null != group.mBigrams) {
-                for (WeightedString bigram : group.mBigrams) {
-                    final int offset = getOffsetToTargetCharGroupDuringUpdate(nodeArray,
-                            groupSize + size + FormatSpec.GROUP_FLAGS_SIZE,
-                            FusionDictionary.findWordInTree(dict.mRootNodeArray, bigram.mWord));
-                    groupSize += getByteSize(offset) + FormatSpec.GROUP_FLAGS_SIZE;
-                }
-            }
-            group.mCachedSize = groupSize;
-            size += groupSize;
-        }
-        if (formatOptions.mSupportsDynamicUpdate) {
-            size += FormatSpec.FORWARD_LINK_ADDRESS_SIZE;
-        }
-        if (nodeArray.mCachedSize != size) {
-            nodeArray.mCachedSize = size;
-            changed = true;
-        }
-        return changed;
-    }
-
-    /**
-     * Initializes the cached addresses of node arrays and their containing nodes from their size.
-     *
-     * @param flatNodes the list of node arrays.
-     * @param formatOptions file format options.
-     * @return the byte size of the entire stack.
-     */
-    private static int initializeNodeArraysCachedAddresses(final ArrayList<PtNodeArray> flatNodes,
-            final FormatOptions formatOptions) {
-        int nodeArrayOffset = 0;
-        for (final PtNodeArray nodeArray : flatNodes) {
-            nodeArray.mCachedAddressBeforeUpdate = nodeArrayOffset;
-            int groupCountSize = getGroupCountSize(nodeArray);
-            int groupOffset = 0;
-            for (final CharGroup g : nodeArray.mData) {
-                g.mCachedAddressBeforeUpdate = g.mCachedAddressAfterUpdate =
-                        groupCountSize + nodeArrayOffset + groupOffset;
-                groupOffset += g.mCachedSize;
-            }
-            final int nodeSize = groupCountSize + groupOffset
-                    + (formatOptions.mSupportsDynamicUpdate
-                            ? FormatSpec.FORWARD_LINK_ADDRESS_SIZE : 0);
-            nodeArrayOffset += nodeArray.mCachedSize;
-        }
-        return nodeArrayOffset;
-    }
-
-    /**
-     * Updates the cached addresses of node arrays after recomputing their new positions.
-     *
-     * @param flatNodes the list of node arrays.
-     */
-    private static void updateNodeArraysCachedAddresses(final ArrayList<PtNodeArray> flatNodes) {
-        for (final PtNodeArray nodeArray : flatNodes) {
-            nodeArray.mCachedAddressBeforeUpdate = nodeArray.mCachedAddressAfterUpdate;
-            for (final CharGroup g : nodeArray.mData) {
-                g.mCachedAddressBeforeUpdate = g.mCachedAddressAfterUpdate;
-            }
-        }
-    }
-
-    /**
-     * Compute the cached parent addresses after all has been updated.
-     *
-     * The parent addresses are used by some binary formats at write-to-disk time. Not all formats
-     * need them. In particular, version 2 does not need them, and version 3 does.
-     *
-     * @param flatNodes the flat array of node arrays to fill in
-     */
-    private static void computeParentAddresses(final ArrayList<PtNodeArray> flatNodes) {
-        for (final PtNodeArray nodeArray : flatNodes) {
-            for (final CharGroup group : nodeArray.mData) {
-                if (null != group.mChildren) {
-                    // Assign my address to children's parent address
-                    // Here BeforeUpdate and AfterUpdate addresses have the same value, so it
-                    // does not matter which we use.
-                    group.mChildren.mCachedParentAddress = group.mCachedAddressAfterUpdate
-                            - group.mChildren.mCachedAddressAfterUpdate;
-                }
-            }
-        }
-    }
-
-    /**
-     * Compute the addresses and sizes of an ordered list of node arrays.
-     *
-     * This method takes a list of node arrays and will update their cached address and size
-     * values so that they can be written into a file. It determines the smallest size each of the
-     * nodes arrays can be given the addresses of its children and attributes, and store that into
-     * each node.
-     * The order of the node is given by the order of the array. This method makes no effort
-     * to find a good order; it only mechanically computes the size this order results in.
-     *
-     * @param dict the dictionary
-     * @param flatNodes the ordered list of nodes arrays
-     * @param formatOptions file format options.
-     * @return the same array it was passed. The nodes have been updated for address and size.
-     */
-    private static ArrayList<PtNodeArray> computeAddresses(final FusionDictionary dict,
-            final ArrayList<PtNodeArray> flatNodes, final FormatOptions formatOptions) {
-        // First get the worst possible sizes and offsets
-        for (final PtNodeArray n : flatNodes) calculateNodeArrayMaximumSize(n, formatOptions);
-        final int offset = initializeNodeArraysCachedAddresses(flatNodes, formatOptions);
-
-        MakedictLog.i("Compressing the array addresses. Original size : " + offset);
-        MakedictLog.i("(Recursively seen size : " + offset + ")");
-
-        int passes = 0;
-        boolean changesDone = false;
-        do {
-            changesDone = false;
-            int nodeArrayStartOffset = 0;
-            for (final PtNodeArray nodeArray : flatNodes) {
-                nodeArray.mCachedAddressAfterUpdate = nodeArrayStartOffset;
-                final int oldNodeArraySize = nodeArray.mCachedSize;
-                final boolean changed = computeActualNodeArraySize(nodeArray, dict, formatOptions);
-                final int newNodeArraySize = nodeArray.mCachedSize;
-                if (oldNodeArraySize < newNodeArraySize) {
-                    throw new RuntimeException("Increased size ?!");
-                }
-                nodeArrayStartOffset += newNodeArraySize;
-                changesDone |= changed;
-            }
-            updateNodeArraysCachedAddresses(flatNodes);
-            ++passes;
-            if (passes > MAX_PASSES) throw new RuntimeException("Too many passes - probably a bug");
-        } while (changesDone);
-
-        if (formatOptions.mSupportsDynamicUpdate) {
-            computeParentAddresses(flatNodes);
-        }
-        final PtNodeArray lastNodeArray = flatNodes.get(flatNodes.size() - 1);
-        MakedictLog.i("Compression complete in " + passes + " passes.");
-        MakedictLog.i("After address compression : "
-                + (lastNodeArray.mCachedAddressAfterUpdate + lastNodeArray.mCachedSize));
-
-        return flatNodes;
-    }
-
-    /**
-     * Sanity-checking method.
-     *
-     * This method checks a list of node arrays for juxtaposition, that is, it will do
-     * nothing if each node array's cached address is actually the previous node array's address
-     * plus the previous node's size.
-     * If this is not the case, it will throw an exception.
-     *
-     * @param arrays the list of node arrays to check
-     */
-    private static void checkFlatNodeArrayList(final ArrayList<PtNodeArray> arrays) {
-        int offset = 0;
-        int index = 0;
-        for (final PtNodeArray nodeArray : arrays) {
-            // BeforeUpdate and AfterUpdate addresses are the same here, so it does not matter
-            // which we use.
-            if (nodeArray.mCachedAddressAfterUpdate != offset) {
-                throw new RuntimeException("Wrong address for node " + index
-                        + " : expected " + offset + ", got " + nodeArray.mCachedAddressAfterUpdate);
-            }
-            ++index;
-            offset += nodeArray.mCachedSize;
-        }
-    }
-
-    /**
-     * Helper method to write a variable-size address to a file.
-     *
-     * @param buffer the buffer to write to.
-     * @param index the index in the buffer to write the address to.
-     * @param address the address to write.
-     * @return the size in bytes the address actually took.
-     */
-    private static int writeVariableAddress(final byte[] buffer, int index, final int address) {
-        switch (getByteSize(address)) {
-        case 1:
-            buffer[index++] = (byte)address;
-            return 1;
-        case 2:
-            buffer[index++] = (byte)(0xFF & (address >> 8));
-            buffer[index++] = (byte)(0xFF & address);
-            return 2;
-        case 3:
-            buffer[index++] = (byte)(0xFF & (address >> 16));
-            buffer[index++] = (byte)(0xFF & (address >> 8));
-            buffer[index++] = (byte)(0xFF & address);
-            return 3;
-        case 0:
-            return 0;
-        default:
-            throw new RuntimeException("Address " + address + " has a strange size");
-        }
-    }
-
-    /**
-     * Helper method to write a variable-size signed address to a file.
-     *
-     * @param buffer the buffer to write to.
-     * @param index the index in the buffer to write the address to.
-     * @param address the address to write.
-     * @return the size in bytes the address actually took.
-     */
-    private static int writeVariableSignedAddress(final byte[] buffer, int index,
-            final int address) {
-        if (!BinaryDictIOUtils.hasChildrenAddress(address)) {
-            buffer[index] = buffer[index + 1] = buffer[index + 2] = 0;
-        } else {
-            final int absAddress = Math.abs(address);
-            buffer[index++] =
-                    (byte)((address < 0 ? FormatSpec.MSB8 : 0) | (0xFF & (absAddress >> 16)));
-            buffer[index++] = (byte)(0xFF & (absAddress >> 8));
-            buffer[index++] = (byte)(0xFF & absAddress);
-        }
-        return 3;
-    }
-
-    /**
-     * Makes the flag value for a char group.
-     *
-     * @param hasMultipleChars whether the group has multiple chars.
-     * @param isTerminal whether the group is terminal.
-     * @param childrenAddressSize the size of a children address.
-     * @param hasShortcuts whether the group has shortcuts.
-     * @param hasBigrams whether the group has bigrams.
-     * @param isNotAWord whether the group is not a word.
-     * @param isBlackListEntry whether the group is a blacklist entry.
-     * @param formatOptions file format options.
-     * @return the flags
-     */
-    static int makeCharGroupFlags(final boolean hasMultipleChars, final boolean isTerminal,
-            final int childrenAddressSize, final boolean hasShortcuts, final boolean hasBigrams,
-            final boolean isNotAWord, final boolean isBlackListEntry,
-            final FormatOptions formatOptions) {
-        byte flags = 0;
-        if (hasMultipleChars) flags |= FormatSpec.FLAG_HAS_MULTIPLE_CHARS;
-        if (isTerminal) flags |= FormatSpec.FLAG_IS_TERMINAL;
-        if (formatOptions.mSupportsDynamicUpdate) {
-            flags |= FormatSpec.FLAG_IS_NOT_MOVED;
-        } else if (true) {
-            switch (childrenAddressSize) {
-                case 1:
-                    flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_ONEBYTE;
-                    break;
-                case 2:
-                    flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_TWOBYTES;
-                    break;
-                case 3:
-                    flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_THREEBYTES;
-                    break;
-                case 0:
-                    flags |= FormatSpec.FLAG_GROUP_ADDRESS_TYPE_NOADDRESS;
-                    break;
-                default:
-                    throw new RuntimeException("Node with a strange address");
-            }
-        }
-        if (hasShortcuts) flags |= FormatSpec.FLAG_HAS_SHORTCUT_TARGETS;
-        if (hasBigrams) flags |= FormatSpec.FLAG_HAS_BIGRAMS;
-        if (isNotAWord) flags |= FormatSpec.FLAG_IS_NOT_A_WORD;
-        if (isBlackListEntry) flags |= FormatSpec.FLAG_IS_BLACKLISTED;
-        return flags;
-    }
-
-    private static byte makeCharGroupFlags(final CharGroup group, final int groupAddress,
-            final int childrenOffset, final FormatOptions formatOptions) {
-        return (byte) makeCharGroupFlags(group.mChars.length > 1, group.mFrequency >= 0,
-                getByteSize(childrenOffset), group.mShortcutTargets != null, group.mBigrams != null,
-                group.mIsNotAWord, group.mIsBlacklistEntry, formatOptions);
-    }
-
-    /**
-     * Makes the flag value for a bigram.
-     *
-     * @param more whether there are more bigrams after this one.
-     * @param offset the offset of the bigram.
-     * @param bigramFrequency the frequency of the bigram, 0..255.
-     * @param unigramFrequency the unigram frequency of the same word, 0..255.
-     * @param word the second bigram, for debugging purposes
-     * @return the flags
-     */
-    private static final int makeBigramFlags(final boolean more, final int offset,
-            int bigramFrequency, final int unigramFrequency, final String word) {
-        int bigramFlags = (more ? FormatSpec.FLAG_ATTRIBUTE_HAS_NEXT : 0)
-                + (offset < 0 ? FormatSpec.FLAG_ATTRIBUTE_OFFSET_NEGATIVE : 0);
-        switch (getByteSize(offset)) {
-        case 1:
-            bigramFlags |= FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE;
-            break;
-        case 2:
-            bigramFlags |= FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES;
-            break;
-        case 3:
-            bigramFlags |= FormatSpec.FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES;
-            break;
-        default:
-            throw new RuntimeException("Strange offset size");
-        }
-        if (unigramFrequency > bigramFrequency) {
-            MakedictLog.e("Unigram freq is superior to bigram freq for \"" + word
-                    + "\". Bigram freq is " + bigramFrequency + ", unigram freq for "
-                    + word + " is " + unigramFrequency);
-            bigramFrequency = unigramFrequency;
-        }
-        // We compute the difference between 255 (which means probability = 1) and the
-        // unigram score. We split this into a number of discrete steps.
-        // Now, the steps are numbered 0~15; 0 represents an increase of 1 step while 15
-        // represents an increase of 16 steps: a value of 15 will be interpreted as the median
-        // value of the 16th step. In all justice, if the bigram frequency is low enough to be
-        // rounded below the first step (which means it is less than half a step higher than the
-        // unigram frequency) then the unigram frequency itself is the best approximation of the
-        // bigram freq that we could possibly supply, hence we should *not* include this bigram
-        // in the file at all.
-        // until this is done, we'll write 0 and slightly overestimate this case.
-        // In other words, 0 means "between 0.5 step and 1.5 step", 1 means "between 1.5 step
-        // and 2.5 steps", and 15 means "between 15.5 steps and 16.5 steps". So we want to
-        // divide our range [unigramFreq..MAX_TERMINAL_FREQUENCY] in 16.5 steps to get the
-        // step size. Then we compute the start of the first step (the one where value 0 starts)
-        // by adding half-a-step to the unigramFrequency. From there, we compute the integer
-        // number of steps to the bigramFrequency. One last thing: we want our steps to include
-        // their lower bound and exclude their higher bound so we need to have the first step
-        // start at exactly 1 unit higher than floor(unigramFreq + half a step).
-        // Note : to reconstruct the score, the dictionary reader will need to divide
-        // MAX_TERMINAL_FREQUENCY - unigramFreq by 16.5 likewise to get the value of the step,
-        // and add (discretizedFrequency + 0.5 + 0.5) times this value to get the best
-        // approximation. (0.5 to get the first step start, and 0.5 to get the middle of the
-        // step pointed by the discretized frequency.
-        final float stepSize =
-                (FormatSpec.MAX_TERMINAL_FREQUENCY - unigramFrequency)
-                / (1.5f + FormatSpec.MAX_BIGRAM_FREQUENCY);
-        final float firstStepStart = 1 + unigramFrequency + (stepSize / 2.0f);
-        final int discretizedFrequency = (int)((bigramFrequency - firstStepStart) / stepSize);
-        // If the bigram freq is less than half-a-step higher than the unigram freq, we get -1
-        // here. The best approximation would be the unigram freq itself, so we should not
-        // include this bigram in the dictionary. For now, register as 0, and live with the
-        // small over-estimation that we get in this case. TODO: actually remove this bigram
-        // if discretizedFrequency < 0.
-        final int finalBigramFrequency = discretizedFrequency > 0 ? discretizedFrequency : 0;
-        bigramFlags += finalBigramFrequency & FormatSpec.FLAG_ATTRIBUTE_FREQUENCY;
-        return bigramFlags;
-    }
-
-    /**
-     * Makes the 2-byte value for options flags.
-     */
-    private static final int makeOptionsValue(final FusionDictionary dictionary,
-            final FormatOptions formatOptions) {
-        final DictionaryOptions options = dictionary.mOptions;
-        final boolean hasBigrams = dictionary.hasBigrams();
-        return (options.mFrenchLigatureProcessing ? FormatSpec.FRENCH_LIGATURE_PROCESSING_FLAG : 0)
-                + (options.mGermanUmlautProcessing ? FormatSpec.GERMAN_UMLAUT_PROCESSING_FLAG : 0)
-                + (hasBigrams ? FormatSpec.CONTAINS_BIGRAMS_FLAG : 0)
-                + (formatOptions.mSupportsDynamicUpdate ? FormatSpec.SUPPORTS_DYNAMIC_UPDATE : 0);
-    }
-
-    /**
-     * Makes the flag value for a shortcut.
-     *
-     * @param more whether there are more attributes after this one.
-     * @param frequency the frequency of the attribute, 0..15
-     * @return the flags
-     */
-    static final int makeShortcutFlags(final boolean more, final int frequency) {
-        return (more ? FormatSpec.FLAG_ATTRIBUTE_HAS_NEXT : 0)
-                + (frequency & FormatSpec.FLAG_ATTRIBUTE_FREQUENCY);
-    }
-
-    private static final int writeParentAddress(final byte[] buffer, final int index,
-            final int address, final FormatOptions formatOptions) {
-        if (BinaryDictIOUtils.supportsDynamicUpdate(formatOptions)) {
-            if (address == FormatSpec.NO_PARENT_ADDRESS) {
-                buffer[index] = buffer[index + 1] = buffer[index + 2] = 0;
-            } else {
-                final int absAddress = Math.abs(address);
-                assert(absAddress <= FormatSpec.SINT24_MAX);
-                buffer[index] = (byte)((address < 0 ? FormatSpec.MSB8 : 0)
-                        | ((absAddress >> 16) & 0xFF));
-                buffer[index + 1] = (byte)((absAddress >> 8) & 0xFF);
-                buffer[index + 2] = (byte)(absAddress & 0xFF);
-            }
-            return index + 3;
-        } else {
-            return index;
-        }
-    }
-
-    /**
-     * Write a node array to memory. The node array is expected to have its final position cached.
-     *
-     * @param dict the dictionary the node array is a part of (for relative offsets).
-     * @param buffer the memory buffer to write to.
-     * @param nodeArray the node array to write.
-     * @param formatOptions file format options.
-     * @return the address of the END of the node.
-     */
-    @SuppressWarnings("unused")
-    private static int writePlacedNode(final FusionDictionary dict, byte[] buffer,
-            final PtNodeArray nodeArray, final FormatOptions formatOptions) {
-        // TODO: Make the code in common with BinaryDictIOUtils#writeCharGroup
-        int index = nodeArray.mCachedAddressAfterUpdate;
-
-        final int groupCount = nodeArray.mData.size();
-        final int countSize = getGroupCountSize(nodeArray);
-        final int parentAddress = nodeArray.mCachedParentAddress;
-        if (1 == countSize) {
-            buffer[index++] = (byte)groupCount;
-        } else if (2 == countSize) {
-            // We need to signal 2-byte size by setting the top bit of the MSB to 1, so
-            // we | 0x80 to do this.
-            buffer[index++] = (byte)((groupCount >> 8) | 0x80);
-            buffer[index++] = (byte)(groupCount & 0xFF);
-        } else {
-            throw new RuntimeException("Strange size from getGroupCountSize : " + countSize);
-        }
-        int groupAddress = index;
-        for (int i = 0; i < groupCount; ++i) {
-            final CharGroup group = nodeArray.mData.get(i);
-            if (index != group.mCachedAddressAfterUpdate) {
-                throw new RuntimeException("Bug: write index is not the same as the cached address "
-                        + "of the group : " + index + " <> " + group.mCachedAddressAfterUpdate);
-            }
-            groupAddress += getGroupHeaderSize(group, formatOptions);
-            // Sanity checks.
-            if (DBG && group.mFrequency > FormatSpec.MAX_TERMINAL_FREQUENCY) {
-                throw new RuntimeException("A node has a frequency > "
-                        + FormatSpec.MAX_TERMINAL_FREQUENCY
-                        + " : " + group.mFrequency);
-            }
-            if (group.mFrequency >= 0) groupAddress += FormatSpec.GROUP_FREQUENCY_SIZE;
-            final int childrenOffset = null == group.mChildren
-                    ? FormatSpec.NO_CHILDREN_ADDRESS
-                            : group.mChildren.mCachedAddressAfterUpdate - groupAddress;
-            buffer[index++] =
-                    makeCharGroupFlags(group, groupAddress, childrenOffset, formatOptions);
-
-            if (parentAddress == FormatSpec.NO_PARENT_ADDRESS) {
-                index = writeParentAddress(buffer, index, parentAddress, formatOptions);
-            } else {
-                index = writeParentAddress(buffer, index, parentAddress
-                        + (nodeArray.mCachedAddressAfterUpdate - group.mCachedAddressAfterUpdate),
-                        formatOptions);
-            }
-
-            index = CharEncoding.writeCharArray(group.mChars, buffer, index);
-            if (group.hasSeveralChars()) {
-                buffer[index++] = FormatSpec.GROUP_CHARACTERS_TERMINATOR;
-            }
-            if (group.mFrequency >= 0) {
-                buffer[index++] = (byte) group.mFrequency;
-            }
-
-            final int shift;
-            if (formatOptions.mSupportsDynamicUpdate) {
-                shift = writeVariableSignedAddress(buffer, index, childrenOffset);
-            } else {
-                shift = writeVariableAddress(buffer, index, childrenOffset);
-            }
-            index += shift;
-            groupAddress += shift;
-
-            // Write shortcuts
-            if (null != group.mShortcutTargets) {
-                final int indexOfShortcutByteSize = index;
-                index += FormatSpec.GROUP_SHORTCUT_LIST_SIZE_SIZE;
-                groupAddress += FormatSpec.GROUP_SHORTCUT_LIST_SIZE_SIZE;
-                final Iterator<WeightedString> shortcutIterator = group.mShortcutTargets.iterator();
-                while (shortcutIterator.hasNext()) {
-                    final WeightedString target = shortcutIterator.next();
-                    ++groupAddress;
-                    int shortcutFlags = makeShortcutFlags(shortcutIterator.hasNext(),
-                            target.mFrequency);
-                    buffer[index++] = (byte)shortcutFlags;
-                    final int shortcutShift = CharEncoding.writeString(buffer, index, target.mWord);
-                    index += shortcutShift;
-                    groupAddress += shortcutShift;
-                }
-                final int shortcutByteSize = index - indexOfShortcutByteSize;
-                if (shortcutByteSize > 0xFFFF) {
-                    throw new RuntimeException("Shortcut list too large");
-                }
-                buffer[indexOfShortcutByteSize] = (byte)(shortcutByteSize >> 8);
-                buffer[indexOfShortcutByteSize + 1] = (byte)(shortcutByteSize & 0xFF);
-            }
-            // Write bigrams
-            if (null != group.mBigrams) {
-                final Iterator<WeightedString> bigramIterator = group.mBigrams.iterator();
-                while (bigramIterator.hasNext()) {
-                    final WeightedString bigram = bigramIterator.next();
-                    final CharGroup target =
-                            FusionDictionary.findWordInTree(dict.mRootNodeArray, bigram.mWord);
-                    final int addressOfBigram = target.mCachedAddressAfterUpdate;
-                    final int unigramFrequencyForThisWord = target.mFrequency;
-                    ++groupAddress;
-                    final int offset = addressOfBigram - groupAddress;
-                    int bigramFlags = makeBigramFlags(bigramIterator.hasNext(), offset,
-                            bigram.mFrequency, unigramFrequencyForThisWord, bigram.mWord);
-                    buffer[index++] = (byte)bigramFlags;
-                    final int bigramShift = writeVariableAddress(buffer, index, Math.abs(offset));
-                    index += bigramShift;
-                    groupAddress += bigramShift;
-                }
-            }
-
-        }
-        if (formatOptions.mSupportsDynamicUpdate) {
-            buffer[index] = buffer[index + 1] = buffer[index + 2]
-                    = FormatSpec.NO_FORWARD_LINK_ADDRESS;
-            index += FormatSpec.FORWARD_LINK_ADDRESS_SIZE;
-        }
-        if (index != nodeArray.mCachedAddressAfterUpdate + nodeArray.mCachedSize) {
-            throw new RuntimeException(
-                    "Not the same size : written " + (index - nodeArray.mCachedAddressAfterUpdate)
-                     + " bytes from a node that should have " + nodeArray.mCachedSize + " bytes");
-        }
-        return index;
-    }
-
-    /**
-     * Dumps a collection of useful statistics about a list of node arrays.
-     *
-     * This prints purely informative stuff, like the total estimated file size, the
-     * number of node arrays, of character groups, the repartition of each address size, etc
-     *
-     * @param nodeArrays the list of node arrays.
-     */
-    private static void showStatistics(ArrayList<PtNodeArray> nodeArrays) {
-        int firstTerminalAddress = Integer.MAX_VALUE;
-        int lastTerminalAddress = Integer.MIN_VALUE;
-        int size = 0;
-        int charGroups = 0;
-        int maxGroups = 0;
-        int maxRuns = 0;
-        for (final PtNodeArray nodeArray : nodeArrays) {
-            if (maxGroups < nodeArray.mData.size()) maxGroups = nodeArray.mData.size();
-            for (final CharGroup cg : nodeArray.mData) {
-                ++charGroups;
-                if (cg.mChars.length > maxRuns) maxRuns = cg.mChars.length;
-                if (cg.mFrequency >= 0) {
-                    if (nodeArray.mCachedAddressAfterUpdate < firstTerminalAddress)
-                        firstTerminalAddress = nodeArray.mCachedAddressAfterUpdate;
-                    if (nodeArray.mCachedAddressAfterUpdate > lastTerminalAddress)
-                        lastTerminalAddress = nodeArray.mCachedAddressAfterUpdate;
-                }
-            }
-            if (nodeArray.mCachedAddressAfterUpdate + nodeArray.mCachedSize > size) {
-                size = nodeArray.mCachedAddressAfterUpdate + nodeArray.mCachedSize;
-            }
-        }
-        final int[] groupCounts = new int[maxGroups + 1];
-        final int[] runCounts = new int[maxRuns + 1];
-        for (final PtNodeArray nodeArray : nodeArrays) {
-            ++groupCounts[nodeArray.mData.size()];
-            for (final CharGroup cg : nodeArray.mData) {
-                ++runCounts[cg.mChars.length];
-            }
-        }
-
-        MakedictLog.i("Statistics:\n"
-                + "  total file size " + size + "\n"
-                + "  " + nodeArrays.size() + " node arrays\n"
-                + "  " + charGroups + " groups (" + ((float)charGroups / nodeArrays.size())
-                        + " groups per node)\n"
-                + "  first terminal at " + firstTerminalAddress + "\n"
-                + "  last terminal at " + lastTerminalAddress + "\n"
-                + "  Group stats : max = " + maxGroups);
-        for (int i = 0; i < groupCounts.length; ++i) {
-            MakedictLog.i("    " + i + " : " + groupCounts[i]);
-        }
-        MakedictLog.i("  Character run stats : max = " + maxRuns);
-        for (int i = 0; i < runCounts.length; ++i) {
-            MakedictLog.i("    " + i + " : " + runCounts[i]);
-        }
-    }
-
-    /**
-     * Dumps a FusionDictionary to a file.
-     *
-     * This is the public entry point to write a dictionary to a file.
-     *
-     * @param destination the stream to write the binary data to.
-     * @param dict the dictionary to write.
-     * @param formatOptions file format options.
-     */
-    public static void writeDictionaryBinary(final OutputStream destination,
-            final FusionDictionary dict, final FormatOptions formatOptions)
-            throws IOException, UnsupportedFormatException {
-
-        // Addresses are limited to 3 bytes, but since addresses can be relative to each node
-        // array, the structure itself is not limited to 16MB. However, if it is over 16MB deciding
-        // the order of the node arrays becomes a quite complicated problem, because though the
-        // dictionary itself does not have a size limit, each node array must still be within 16MB
-        // of all its children and parents. As long as this is ensured, the dictionary file may
-        // grow to any size.
-
-        final int version = formatOptions.mVersion;
-        if (version < FormatSpec.MINIMUM_SUPPORTED_VERSION
-                || version > FormatSpec.MAXIMUM_SUPPORTED_VERSION) {
-            throw new UnsupportedFormatException("Requested file format version " + version
-                    + ", but this implementation only supports versions "
-                    + FormatSpec.MINIMUM_SUPPORTED_VERSION + " through "
-                    + FormatSpec.MAXIMUM_SUPPORTED_VERSION);
-        }
-
-        ByteArrayOutputStream headerBuffer = new ByteArrayOutputStream(256);
-
-        // The magic number in big-endian order.
-        // Magic number for all versions.
-        headerBuffer.write((byte) (0xFF & (FormatSpec.MAGIC_NUMBER >> 24)));
-        headerBuffer.write((byte) (0xFF & (FormatSpec.MAGIC_NUMBER >> 16)));
-        headerBuffer.write((byte) (0xFF & (FormatSpec.MAGIC_NUMBER >> 8)));
-        headerBuffer.write((byte) (0xFF & FormatSpec.MAGIC_NUMBER));
-        // Dictionary version.
-        headerBuffer.write((byte) (0xFF & (version >> 8)));
-        headerBuffer.write((byte) (0xFF & version));
-
-        // Options flags
-        final int options = makeOptionsValue(dict, formatOptions);
-        headerBuffer.write((byte) (0xFF & (options >> 8)));
-        headerBuffer.write((byte) (0xFF & options));
-        final int headerSizeOffset = headerBuffer.size();
-        // Placeholder to be written later with header size.
-        for (int i = 0; i < 4; ++i) {
-            headerBuffer.write(0);
-        }
-        // Write out the options.
-        for (final String key : dict.mOptions.mAttributes.keySet()) {
-            final String value = dict.mOptions.mAttributes.get(key);
-            CharEncoding.writeString(headerBuffer, key);
-            CharEncoding.writeString(headerBuffer, value);
-        }
-        final int size = headerBuffer.size();
-        final byte[] bytes = headerBuffer.toByteArray();
-        // Write out the header size.
-        bytes[headerSizeOffset] = (byte) (0xFF & (size >> 24));
-        bytes[headerSizeOffset + 1] = (byte) (0xFF & (size >> 16));
-        bytes[headerSizeOffset + 2] = (byte) (0xFF & (size >> 8));
-        bytes[headerSizeOffset + 3] = (byte) (0xFF & (size >> 0));
-        destination.write(bytes);
-
-        headerBuffer.close();
-
-        // Leave the choice of the optimal node order to the flattenTree function.
-        MakedictLog.i("Flattening the tree...");
-        ArrayList<PtNodeArray> flatNodes = flattenTree(dict.mRootNodeArray);
-
-        MakedictLog.i("Computing addresses...");
-        computeAddresses(dict, flatNodes, formatOptions);
-        MakedictLog.i("Checking array...");
-        if (DBG) checkFlatNodeArrayList(flatNodes);
-
-        // Create a buffer that matches the final dictionary size.
-        final PtNodeArray lastNodeArray = flatNodes.get(flatNodes.size() - 1);
-        final int bufferSize = lastNodeArray.mCachedAddressAfterUpdate + lastNodeArray.mCachedSize;
-        final byte[] buffer = new byte[bufferSize];
-        int index = 0;
-
-        MakedictLog.i("Writing file...");
-        int dataEndOffset = 0;
-        for (PtNodeArray nodeArray : flatNodes) {
-            dataEndOffset = writePlacedNode(dict, buffer, nodeArray, formatOptions);
-        }
-
-        if (DBG) showStatistics(flatNodes);
-
-        destination.write(buffer, 0, dataEndOffset);
-
-        destination.close();
-        MakedictLog.i("Done");
-    }
-}