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Optional diff utils use

This commit is contained in:
Denis Karmyshakov 2017-06-30 17:48:57 +03:00
parent 3d4d78708a
commit eb17e79459
16 changed files with 1685 additions and 292 deletions
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2
build.gradle
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@ -16,7 +16,7 @@ android {
}
dependencies {
provided 'com.android.support:support-annotations:25.3.1'
provided 'com.android.support:support-annotations:25.4.0'
provided 'io.reactivex:rxandroid:1.2.1'
provided 'io.reactivex:rxjava:1.3.0'
}

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src/main/java/ru/touchin/roboswag/core/android/support/v7/util/BatchingListUpdateCallback.java Normal file
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@ -0,0 +1,126 @@
/*
* Copyright (C) 2016 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 ru.touchin.roboswag.core.android.support.v7.util;
/**
* Wraps a {@link ListUpdateCallback} callback and batches operations that can be merged.
*
* <p>For instance, when 2 add operations comes that adds 2 consecutive elements,
* BatchingListUpdateCallback merges them and calls the wrapped callback only once.
*
* <p>This is a general purpose class and is also used by
* {@link DiffUtil.DiffResult DiffResult}
*
* <p>If you use this class to batch updates, you must call {@link #dispatchLastEvent()} when the
* stream of update events drain.
*/
@SuppressWarnings({"PMD", "checkstyle:all"})
public class BatchingListUpdateCallback implements ListUpdateCallback {
private static final int TYPE_NONE = 0;
private static final int TYPE_ADD = 1;
private static final int TYPE_REMOVE = 2;
private static final int TYPE_CHANGE = 3;
private final ListUpdateCallback mWrapped;
private int mLastEventType = TYPE_NONE;
private int mLastEventPosition = -1;
private int mLastEventCount = -1;
private Object mLastEventPayload = null;
public BatchingListUpdateCallback(ListUpdateCallback callback) {
mWrapped = callback;
}
/**
* BatchingListUpdateCallback holds onto the last event to see if it can be merged with the
* next one. When stream of events finish, you should call this method to dispatch the last
* event.
*/
public void dispatchLastEvent() {
if (mLastEventType == TYPE_NONE) {
return;
}
switch (mLastEventType) {
case TYPE_ADD:
mWrapped.onInserted(mLastEventPosition, mLastEventCount);
break;
case TYPE_REMOVE:
mWrapped.onRemoved(mLastEventPosition, mLastEventCount);
break;
case TYPE_CHANGE:
mWrapped.onChanged(mLastEventPosition, mLastEventCount, mLastEventPayload);
break;
}
mLastEventPayload = null;
mLastEventType = TYPE_NONE;
}
@Override
public void onInserted(int position, int count) {
if (mLastEventType == TYPE_ADD && position >= mLastEventPosition
&& position <= mLastEventPosition + mLastEventCount) {
mLastEventCount += count;
mLastEventPosition = Math.min(position, mLastEventPosition);
return;
}
dispatchLastEvent();
mLastEventPosition = position;
mLastEventCount = count;
mLastEventType = TYPE_ADD;
}
@Override
public void onRemoved(int position, int count) {
if (mLastEventType == TYPE_REMOVE && mLastEventPosition >= position &&
mLastEventPosition <= position + count) {
mLastEventCount += count;
mLastEventPosition = position;
return;
}
dispatchLastEvent();
mLastEventPosition = position;
mLastEventCount = count;
mLastEventType = TYPE_REMOVE;
}
@Override
public void onMoved(int fromPosition, int toPosition) {
dispatchLastEvent(); // moves are not merged
mWrapped.onMoved(fromPosition, toPosition);
}
@Override
public void onChanged(int position, int count, Object payload) {
if (mLastEventType == TYPE_CHANGE &&
!(position > mLastEventPosition + mLastEventCount
|| position + count < mLastEventPosition || mLastEventPayload != payload)) {
// take potential overlap into account
int previousEnd = mLastEventPosition + mLastEventCount;
mLastEventPosition = Math.min(position, mLastEventPosition);
mLastEventCount = Math.max(previousEnd, position + count) - mLastEventPosition;
return;
}
dispatchLastEvent();
mLastEventPosition = position;
mLastEventCount = count;
mLastEventPayload = payload;
mLastEventType = TYPE_CHANGE;
}
}

787
src/main/java/ru/touchin/roboswag/core/android/support/v7/util/DiffUtil.java Normal file
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@ -0,0 +1,787 @@
/*
* Copyright (C) 2016 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 ru.touchin.roboswag.core.android.support.v7.util;
import android.support.annotation.Nullable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
/**
* DiffUtil is a utility class that can calculate the difference between two lists and output a
* list of update operations that converts the first list into the second one.
*
* <p>It can be used to calculate updates for a RecyclerView Adapter.
*
* <p>DiffUtil uses Eugene W. Myers's difference algorithm to calculate the minimal number of updates
* to convert one list into another. Myers's algorithm does not handle items that are moved so
* DiffUtil runs a second pass on the result to detect items that were moved.
*
* <p>If the lists are large, this operation may take significant time so you are advised to run this
* on a background thread, get the {@link DiffResult} then apply it on the RecyclerView on the main
* thread.
*
* <p>This algorithm is optimized for space and uses O(N) space to find the minimal
* number of addition and removal operations between the two lists. It has O(N + D^2) expected time
* performance where D is the length of the edit script.
*
* <p>If move detection is enabled, it takes an additional O(N^2) time where N is the total number of
* added and removed items. If your lists are already sorted by the same constraint (e.g. a created
* timestamp for a list of posts), you can disable move detection to improve performance.
*
* <p>The actual runtime of the algorithm significantly depends on the number of changes in the list
* and the cost of your comparison methods. Below are some average run times for reference:
* (The areSame list is composed of random UUID Strings and the tests are run on Nexus 5X with M)
* <ul>
* <li>100 items and 10 modifications: avg: 0.39 ms, median: 0.35 ms
* <li>100 items and 100 modifications: 3.82 ms, median: 3.75 ms
* <li>100 items and 100 modifications without moves: 2.09 ms, median: 2.06 ms
* <li>1000 items and 50 modifications: avg: 4.67 ms, median: 4.59 ms
* <li>1000 items and 50 modifications without moves: avg: 3.59 ms, median: 3.50 ms
* <li>1000 items and 200 modifications: 27.07 ms, median: 26.92 ms
* <li>1000 items and 200 modifications without moves: 13.54 ms, median: 13.36 ms
* </ul>
*
* <p>Due to implementation constraints, the max size of the list can be 2^26.
*/
@SuppressWarnings({"PMD", "checkstyle:all"})
public class DiffUtil {
private DiffUtil() {
// utility class, no instance.
}
private static final Comparator<Snake> SNAKE_COMPARATOR = new Comparator<Snake>() {
@Override
public int compare(Snake o1, Snake o2) {
int cmpX = o1.x - o2.x;
return cmpX == 0 ? o1.y - o2.y : cmpX;
}
};
// Myers' algorithm uses two lists as axis labels. In DiffUtil's implementation, `x` axis is
// used for old list and `y` axis is used for new list.
/**
* Calculates the list of update operations that can covert one list into the other one.
*
* @param cb The callback that acts as a gateway to the backing list data
*
* @return A DiffResult that contains the information about the edit sequence to convert the
* old list into the new list.
*/
public static DiffResult calculateDiff(Callback cb) {
return calculateDiff(cb, true);
}
/**
* Calculates the list of update operations that can covert one list into the other one.
* <p>
* If your old and new lists are sorted by the same constraint and items never move (swap
* positions), you can disable move detection which takes <code>O(N^2)</code> time where
* N is the number of added, moved, removed items.
*
* @param cb The callback that acts as a gateway to the backing list data
* @param detectMoves True if DiffUtil should try to detect moved items, false otherwise.
*
* @return A DiffResult that contains the information about the edit sequence to convert the
* old list into the new list.
*/
public static DiffResult calculateDiff(Callback cb, boolean detectMoves) {
final int oldSize = cb.getOldListSize();
final int newSize = cb.getNewListSize();
final List<Snake> snakes = new ArrayList<>();
// instead of a recursive implementation, we keep our own stack to avoid potential stack
// overflow exceptions
final List<Range> stack = new ArrayList<>();
stack.add(new Range(0, oldSize, 0, newSize));
final int max = oldSize + newSize + Math.abs(oldSize - newSize);
// allocate forward and backward k-lines. K lines are diagonal lines in the matrix. (see the
// paper for details)
// These arrays lines keep the max reachable position for each k-line.
final int[] forward = new int[max * 2];
final int[] backward = new int[max * 2];
// We pool the ranges to avoid allocations for each recursive call.
final List<Range> rangePool = new ArrayList<>();
while (!stack.isEmpty()) {
final Range range = stack.remove(stack.size() - 1);
final Snake snake = diffPartial(cb, range.oldListStart, range.oldListEnd,
range.newListStart, range.newListEnd, forward, backward, max);
if (snake != null) {
if (snake.size > 0) {
snakes.add(snake);
}
// offset the snake to convert its coordinates from the Range's area to global
snake.x += range.oldListStart;
snake.y += range.newListStart;
// add new ranges for left and right
final Range left = rangePool.isEmpty() ? new Range() : rangePool.remove(
rangePool.size() - 1);
left.oldListStart = range.oldListStart;
left.newListStart = range.newListStart;
if (snake.reverse) {
left.oldListEnd = snake.x;
left.newListEnd = snake.y;
} else {
if (snake.removal) {
left.oldListEnd = snake.x - 1;
left.newListEnd = snake.y;
} else {
left.oldListEnd = snake.x;
left.newListEnd = snake.y - 1;
}
}
stack.add(left);
// re-use range for right
//noinspection UnnecessaryLocalVariable
final Range right = range;
if (snake.reverse) {
if (snake.removal) {
right.oldListStart = snake.x + snake.size + 1;
right.newListStart = snake.y + snake.size;
} else {
right.oldListStart = snake.x + snake.size;
right.newListStart = snake.y + snake.size + 1;
}
} else {
right.oldListStart = snake.x + snake.size;
right.newListStart = snake.y + snake.size;
}
stack.add(right);
} else {
rangePool.add(range);
}
}
// sort snakes
Collections.sort(snakes, SNAKE_COMPARATOR);
return new DiffResult(cb, snakes, forward, backward, detectMoves);
}
private static Snake diffPartial(Callback cb, int startOld, int endOld,
int startNew, int endNew, int[] forward, int[] backward, int kOffset) {
final int oldSize = endOld - startOld;
final int newSize = endNew - startNew;
if (endOld - startOld < 1 || endNew - startNew < 1) {
return null;
}
final int delta = oldSize - newSize;
final int dLimit = (oldSize + newSize + 1) / 2;
Arrays.fill(forward, kOffset - dLimit - 1, kOffset + dLimit + 1, 0);
Arrays.fill(backward, kOffset - dLimit - 1 + delta, kOffset + dLimit + 1 + delta, oldSize);
final boolean checkInFwd = delta % 2 != 0;
for (int d = 0; d <= dLimit; d++) {
for (int k = -d; k <= d; k += 2) {
// find forward path
// we can reach k from k - 1 or k + 1. Check which one is further in the graph
int x;
final boolean removal;
if (k == -d || k != d && forward[kOffset + k - 1] < forward[kOffset + k + 1]) {
x = forward[kOffset + k + 1];
removal = false;
} else {
x = forward[kOffset + k - 1] + 1;
removal = true;
}
// set y based on x
int y = x - k;
// move diagonal as long as items match
while (x < oldSize && y < newSize
&& cb.areItemsTheSame(startOld + x, startNew + y)) {
x++;
y++;
}
forward[kOffset + k] = x;
if (checkInFwd && k >= delta - d + 1 && k <= delta + d - 1) {
if (forward[kOffset + k] >= backward[kOffset + k]) {
Snake outSnake = new Snake();
outSnake.x = backward[kOffset + k];
outSnake.y = outSnake.x - k;
outSnake.size = forward[kOffset + k] - backward[kOffset + k];
outSnake.removal = removal;
outSnake.reverse = false;
return outSnake;
}
}
}
for (int k = -d; k <= d; k += 2) {
// find reverse path at k + delta, in reverse
final int backwardK = k + delta;
int x;
final boolean removal;
if (backwardK == d + delta || backwardK != -d + delta
&& backward[kOffset + backwardK - 1] < backward[kOffset + backwardK + 1]) {
x = backward[kOffset + backwardK - 1];
removal = false;
} else {
x = backward[kOffset + backwardK + 1] - 1;
removal = true;
}
// set y based on x
int y = x - backwardK;
// move diagonal as long as items match
while (x > 0 && y > 0
&& cb.areItemsTheSame(startOld + x - 1, startNew + y - 1)) {
x--;
y--;
}
backward[kOffset + backwardK] = x;
if (!checkInFwd && k + delta >= -d && k + delta <= d) {
if (forward[kOffset + backwardK] >= backward[kOffset + backwardK]) {
Snake outSnake = new Snake();
outSnake.x = backward[kOffset + backwardK];
outSnake.y = outSnake.x - backwardK;
outSnake.size =
forward[kOffset + backwardK] - backward[kOffset + backwardK];
outSnake.removal = removal;
outSnake.reverse = true;
return outSnake;
}
}
}
}
throw new IllegalStateException("DiffUtil hit an unexpected case while trying to calculate"
+ " the optimal path. Please make sure your data is not changing during the"
+ " diff calculation.");
}
/**
* A Callback class used by DiffUtil while calculating the diff between two lists.
*/
public abstract static class Callback {
/**
* Returns the size of the old list.
*
* @return The size of the old list.
*/
public abstract int getOldListSize();
/**
* Returns the size of the new list.
*
* @return The size of the new list.
*/
public abstract int getNewListSize();
/**
* Called by the DiffUtil to decide whether two object represent the same Item.
* <p>
* For example, if your items have unique ids, this method should check their id equality.
*
* @param oldItemPosition The position of the item in the old list
* @param newItemPosition The position of the item in the new list
* @return True if the two items represent the same object or false if they are different.
*/
public abstract boolean areItemsTheSame(int oldItemPosition, int newItemPosition);
/**
* Called by the DiffUtil when it wants to check whether two items have the same data.
* DiffUtil uses this information to detect if the contents of an item has changed.
* <p>
* DiffUtil uses this method to check equality instead of {@link Object#equals(Object)}
* so that you can change its behavior depending on your UI.
* <p>
* This method is called only if {@link #areItemsTheSame(int, int)} returns
* {@code true} for these items.
*
* @param oldItemPosition The position of the item in the old list
* @param newItemPosition The position of the item in the new list which replaces the
* oldItem
* @return True if the contents of the items are the same or false if they are different.
*/
public abstract boolean areContentsTheSame(int oldItemPosition, int newItemPosition);
/**
* When {@link #areItemsTheSame(int, int)} returns {@code true} for two items and
* {@link #areContentsTheSame(int, int)} returns false for them, DiffUtil
* calls this method to get a payload about the change.
* <p>
* Default implementation returns {@code null}.
*
* @param oldItemPosition The position of the item in the old list
* @param newItemPosition The position of the item in the new list
*
* @return A payload object that represents the change between the two items.
*/
@Nullable
public Object getChangePayload(int oldItemPosition, int newItemPosition) {
return null;
}
}
/**
* Snakes represent a match between two lists. It is optionally prefixed or postfixed with an
* add or remove operation. See the Myers' paper for details.
*/
static class Snake {
/**
* Position in the old list
*/
int x;
/**
* Position in the new list
*/
int y;
/**
* Number of matches. Might be 0.
*/
int size;
/**
* If true, this is a removal from the original list followed by {@code size} matches.
* If false, this is an addition from the new list followed by {@code size} matches.
*/
boolean removal;
/**
* If true, the addition or removal is at the end of the snake.
* If false, the addition or removal is at the beginning of the snake.
*/
boolean reverse;
}
/**
* Represents a range in two lists that needs to be solved.
* <p>
* This internal class is used when running Myers' algorithm without recursion.
*/
static class Range {
int oldListStart, oldListEnd;
int newListStart, newListEnd;
public Range() {
}
public Range(int oldListStart, int oldListEnd, int newListStart, int newListEnd) {
this.oldListStart = oldListStart;
this.oldListEnd = oldListEnd;
this.newListStart = newListStart;
this.newListEnd = newListEnd;
}
}
/**
* This class holds the information about the result of a
* {@link DiffUtil#calculateDiff(Callback, boolean)} call.
* <p>
* You can consume the updates in a DiffResult via
* {@link #dispatchUpdatesTo(ListUpdateCallback)}
*/
public static class DiffResult {
/**
* While reading the flags below, keep in mind that when multiple items move in a list,
* Myers's may pick any of them as the anchor item and consider that one NOT_CHANGED while
* picking others as additions and removals. This is completely fine as we later detect
* all moves.
* <p>
* Below, when an item is mentioned to stay in the same "location", it means we won't
* dispatch a move/add/remove for it, it DOES NOT mean the item is still in the same
* position.
*/
// item stayed the same.
private static final int FLAG_NOT_CHANGED = 1;
// item stayed in the same location but changed.
private static final int FLAG_CHANGED = FLAG_NOT_CHANGED << 1;
// Item has moved and also changed.
private static final int FLAG_MOVED_CHANGED = FLAG_CHANGED << 1;
// Item has moved but did not change.
private static final int FLAG_MOVED_NOT_CHANGED = FLAG_MOVED_CHANGED << 1;
// Ignore this update.
// If this is an addition from the new list, it means the item is actually removed from an
// earlier position and its move will be dispatched when we process the matching removal
// from the old list.
// If this is a removal from the old list, it means the item is actually added back to an
// earlier index in the new list and we'll dispatch its move when we are processing that
// addition.
private static final int FLAG_IGNORE = FLAG_MOVED_NOT_CHANGED << 1;
// since we are re-using the int arrays that were created in the Myers' step, we mask
// change flags
private static final int FLAG_OFFSET = 5;
private static final int FLAG_MASK = (1 << FLAG_OFFSET) - 1;
// The Myers' snakes. At this point, we only care about their diagonal sections.
private final List<Snake> mSnakes;
// The list to keep oldItemStatuses. As we traverse old items, we assign flags to them
// which also includes whether they were a real removal or a move (and its new index).
private final int[] mOldItemStatuses;
// The list to keep newItemStatuses. As we traverse new items, we assign flags to them
// which also includes whether they were a real addition or a move(and its old index).
private final int[] mNewItemStatuses;
// The callback that was given to calcualte diff method.
private final Callback mCallback;
private final int mOldListSize;
private final int mNewListSize;
private final boolean mDetectMoves;
/**
* @param callback The callback that was used to calculate the diff
* @param snakes The list of Myers' snakes
* @param oldItemStatuses An int[] that can be re-purposed to keep metadata
* @param newItemStatuses An int[] that can be re-purposed to keep metadata
* @param detectMoves True if this DiffResult will try to detect moved items
*/
DiffResult(Callback callback, List<Snake> snakes, int[] oldItemStatuses,
int[] newItemStatuses, boolean detectMoves) {
mSnakes = snakes;
mOldItemStatuses = oldItemStatuses;
mNewItemStatuses = newItemStatuses;
Arrays.fill(mOldItemStatuses, 0);
Arrays.fill(mNewItemStatuses, 0);
mCallback = callback;
mOldListSize = callback.getOldListSize();
mNewListSize = callback.getNewListSize();
mDetectMoves = detectMoves;
addRootSnake();
findMatchingItems();
}
/**
* We always add a Snake to 0/0 so that we can run loops from end to beginning and be done
* when we run out of snakes.
*/
private void addRootSnake() {
Snake firstSnake = mSnakes.isEmpty() ? null : mSnakes.get(0);
if (firstSnake == null || firstSnake.x != 0 || firstSnake.y != 0) {
Snake root = new Snake();
root.x = 0;
root.y = 0;
root.removal = false;
root.size = 0;
root.reverse = false;
mSnakes.add(0, root);
}
}
/**
* This method traverses each addition / removal and tries to match it to a previous
* removal / addition. This is how we detect move operations.
* <p>
* This class also flags whether an item has been changed or not.
* <p>
* DiffUtil does this pre-processing so that if it is running on a big list, it can be moved
* to background thread where most of the expensive stuff will be calculated and kept in
* the statuses maps. DiffResult uses this pre-calculated information while dispatching
* the updates (which is probably being called on the main thread).
*/
private void findMatchingItems() {
int posOld = mOldListSize;
int posNew = mNewListSize;
// traverse the matrix from right bottom to 0,0.
for (int i = mSnakes.size() - 1; i >= 0; i--) {
final Snake snake = mSnakes.get(i);
final int endX = snake.x + snake.size;
final int endY = snake.y + snake.size;
if (mDetectMoves) {
while (posOld > endX) {
// this is a removal. Check remaining snakes to see if this was added before
findAddition(posOld, posNew, i);
posOld--;
}
while (posNew > endY) {
// this is an addition. Check remaining snakes to see if this was removed
// before
findRemoval(posOld, posNew, i);
posNew--;
}
}
for (int j = 0; j < snake.size; j++) {
// matching items. Check if it is changed or not
final int oldItemPos = snake.x + j;
final int newItemPos = snake.y + j;
final boolean theSame = mCallback
.areContentsTheSame(oldItemPos, newItemPos);
final int changeFlag = theSame ? FLAG_NOT_CHANGED : FLAG_CHANGED;
mOldItemStatuses[oldItemPos] = (newItemPos << FLAG_OFFSET) | changeFlag;
mNewItemStatuses[newItemPos] = (oldItemPos << FLAG_OFFSET) | changeFlag;
}
posOld = snake.x;
posNew = snake.y;
}
}
private void findAddition(int x, int y, int snakeIndex) {
if (mOldItemStatuses[x - 1] != 0) {
return; // already set by a latter item
}
findMatchingItem(x, y, snakeIndex, false);
}
private void findRemoval(int x, int y, int snakeIndex) {
if (mNewItemStatuses[y - 1] != 0) {
return; // already set by a latter item
}
findMatchingItem(x, y, snakeIndex, true);
}
/**
* Finds a matching item that is before the given coordinates in the matrix
* (before : left and above).
*
* @param x The x position in the matrix (position in the old list)
* @param y The y position in the matrix (position in the new list)
* @param snakeIndex The current snake index
* @param removal True if we are looking for a removal, false otherwise
*
* @return True if such item is found.
*/
private boolean findMatchingItem(final int x, final int y, final int snakeIndex,
final boolean removal) {
final int myItemPos;
int curX;
int curY;
if (removal) {
myItemPos = y - 1;
curX = x;
curY = y - 1;
} else {
myItemPos = x - 1;
curX = x - 1;
curY = y;
}
for (int i = snakeIndex; i >= 0; i--) {
final Snake snake = mSnakes.get(i);
final int endX = snake.x + snake.size;
final int endY = snake.y + snake.size;
if (removal) {
// check removals for a match
for (int pos = curX - 1; pos >= endX; pos--) {
if (mCallback.areItemsTheSame(pos, myItemPos)) {
// found!
final boolean theSame = mCallback.areContentsTheSame(pos, myItemPos);
final int changeFlag = theSame ? FLAG_MOVED_NOT_CHANGED
: FLAG_MOVED_CHANGED;
mNewItemStatuses[myItemPos] = (pos << FLAG_OFFSET) | FLAG_IGNORE;
mOldItemStatuses[pos] = (myItemPos << FLAG_OFFSET) | changeFlag;
return true;
}
}
} else {
// check for additions for a match
for (int pos = curY - 1; pos >= endY; pos--) {
if (mCallback.areItemsTheSame(myItemPos, pos)) {
// found
final boolean theSame = mCallback.areContentsTheSame(myItemPos, pos);
final int changeFlag = theSame ? FLAG_MOVED_NOT_CHANGED
: FLAG_MOVED_CHANGED;
mOldItemStatuses[x - 1] = (pos << FLAG_OFFSET) | FLAG_IGNORE;
mNewItemStatuses[pos] = ((x - 1) << FLAG_OFFSET) | changeFlag;
return true;
}
}
}
curX = snake.x;
curY = snake.y;
}
return false;
}
/**
* Dispatches update operations to the given Callback.
* <p>
* These updates are atomic such that the first update call effects every update call that
* comes after it (the same as RecyclerView).
*
* @param updateCallback The callback to receive the update operations.
*/
public void dispatchUpdatesTo(ListUpdateCallback updateCallback) {
final BatchingListUpdateCallback batchingCallback;
if (updateCallback instanceof BatchingListUpdateCallback) {
batchingCallback = (BatchingListUpdateCallback) updateCallback;
} else {
batchingCallback = new BatchingListUpdateCallback(updateCallback);
// replace updateCallback with a batching callback and override references to
// updateCallback so that we don't call it directly by mistake
//noinspection UnusedAssignment
updateCallback = batchingCallback;
}
// These are add/remove ops that are converted to moves. We track their positions until
// their respective update operations are processed.
final List<PostponedUpdate> postponedUpdates = new ArrayList<>();
int posOld = mOldListSize;
int posNew = mNewListSize;
for (int snakeIndex = mSnakes.size() - 1; snakeIndex >= 0; snakeIndex--) {
final Snake snake = mSnakes.get(snakeIndex);
final int snakeSize = snake.size;
final int endX = snake.x + snakeSize;
final int endY = snake.y + snakeSize;
if (endX < posOld) {
dispatchRemovals(postponedUpdates, batchingCallback, endX, posOld - endX, endX);
}
if (endY < posNew) {
dispatchAdditions(postponedUpdates, batchingCallback, endX, posNew - endY,
endY);
}
for (int i = snakeSize - 1; i >= 0; i--) {
if ((mOldItemStatuses[snake.x + i] & FLAG_MASK) == FLAG_CHANGED) {
batchingCallback.onChanged(snake.x + i, 1,
mCallback.getChangePayload(snake.x + i, snake.y + i));
}
}
posOld = snake.x;
posNew = snake.y;
}
batchingCallback.dispatchLastEvent();
}
private static PostponedUpdate removePostponedUpdate(List<PostponedUpdate> updates,
int pos, boolean removal) {
for (int i = updates.size() - 1; i >= 0; i--) {
final PostponedUpdate update = updates.get(i);
if (update.posInOwnerList == pos && update.removal == removal) {
updates.remove(i);
for (int j = i; j < updates.size(); j++) {
// offset other ops since they swapped positions
updates.get(j).currentPos += removal ? 1 : -1;
}
return update;
}
}
return null;
}
private void dispatchAdditions(List<PostponedUpdate> postponedUpdates,
ListUpdateCallback updateCallback, int start, int count, int globalIndex) {
if (!mDetectMoves) {
updateCallback.onInserted(start, count);
return;
}
for (int i = count - 1; i >= 0; i--) {
int status = mNewItemStatuses[globalIndex + i] & FLAG_MASK;
switch (status) {
case 0: // real addition
updateCallback.onInserted(start, 1);
for (PostponedUpdate update : postponedUpdates) {
update.currentPos += 1;
}
break;
case FLAG_MOVED_CHANGED:
case FLAG_MOVED_NOT_CHANGED:
final int pos = mNewItemStatuses[globalIndex + i] >> FLAG_OFFSET;
final PostponedUpdate update = removePostponedUpdate(postponedUpdates, pos,
true);
// the item was moved from that position
//noinspection ConstantConditions
updateCallback.onMoved(update.currentPos, start);
if (status == FLAG_MOVED_CHANGED) {
// also dispatch a change
updateCallback.onChanged(start, 1,
mCallback.getChangePayload(pos, globalIndex + i));
}
break;
case FLAG_IGNORE: // ignoring this
postponedUpdates.add(new PostponedUpdate(globalIndex + i, start, false));
break;
default:
throw new IllegalStateException(
"unknown flag for pos " + (globalIndex + i) + " " + Long
.toBinaryString(status));
}
}
}
private void dispatchRemovals(List<PostponedUpdate> postponedUpdates,
ListUpdateCallback updateCallback, int start, int count, int globalIndex) {
if (!mDetectMoves) {
updateCallback.onRemoved(start, count);
return;
}
for (int i = count - 1; i >= 0; i--) {
final int status = mOldItemStatuses[globalIndex + i] & FLAG_MASK;
switch (status) {
case 0: // real removal
updateCallback.onRemoved(start + i, 1);
for (PostponedUpdate update : postponedUpdates) {
update.currentPos -= 1;
}
break;
case FLAG_MOVED_CHANGED:
case FLAG_MOVED_NOT_CHANGED:
final int pos = mOldItemStatuses[globalIndex + i] >> FLAG_OFFSET;
final PostponedUpdate update = removePostponedUpdate(postponedUpdates, pos,
false);
// the item was moved to that position. we do -1 because this is a move not
// add and removing current item offsets the target move by 1
//noinspection ConstantConditions
updateCallback.onMoved(start + i, update.currentPos - 1);
if (status == FLAG_MOVED_CHANGED) {
// also dispatch a change
updateCallback.onChanged(update.currentPos - 1, 1,
mCallback.getChangePayload(globalIndex + i, pos));
}
break;
case FLAG_IGNORE: // ignoring this
postponedUpdates.add(new PostponedUpdate(globalIndex + i, start + i, true));
break;
default:
throw new IllegalStateException(
"unknown flag for pos " + (globalIndex + i) + " " + Long
.toBinaryString(status));
}
}
}
}
/**
* Represents an update that we skipped because it was a move.
* <p>
* When an update is skipped, it is tracked as other updates are dispatched until the matching
* add/remove operation is found at which point the tracked position is used to dispatch the
* update.
*/
private static class PostponedUpdate {
int posInOwnerList;
int currentPos;
boolean removal;
public PostponedUpdate(int posInOwnerList, int currentPos, boolean removal) {
this.posInOwnerList = posInOwnerList;
this.currentPos = currentPos;
this.removal = removal;
}
}
}

59
src/main/java/ru/touchin/roboswag/core/android/support/v7/util/ListUpdateCallback.java Normal file
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@ -0,0 +1,59 @@
/*
* Copyright (C) 2016 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 ru.touchin.roboswag.core.android.support.v7.util;
/**
* An interface that can receive Update operations that are applied to a list.
*
* <p>This class can be used together with DiffUtil to detect changes between two lists.
*/
@SuppressWarnings({"PMD", "checkstyle:all"})
public interface ListUpdateCallback {
/**
* Called when {@code count} number of items are inserted at the given position.
*
* @param position The position of the new item.
* @param count The number of items that have been added.
*/
void onInserted(int position, int count);
/**
* Called when {@code count} number of items are removed from the given position.
*
* @param position The position of the item which has been removed.
* @param count The number of items which have been removed.
*/
void onRemoved(int position, int count);
/**
* Called when an item changes its position in the list.
*
* @param fromPosition The previous position of the item before the move.
* @param toPosition The new position of the item.
*/
void onMoved(int fromPosition, int toPosition);
/**
* Called when {@code count} number of items are updated at the given position.
*
* @param position The position of the item which has been updated.
* @param count The number of items which has changed.
*/
void onChanged(int position, int count, Object payload);
}

225
src/main/java/ru/touchin/roboswag/core/observables/collections/Change.java
View File

@ -1,225 +0,0 @@
/*
* Copyright (c) 2015 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
*
* This file is part of RoboSwag library.
*
* 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 ru.touchin.roboswag.core.observables.collections;
import android.support.annotation.NonNull;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
/**
* Created by Gavriil Sitnikov on 23/05/16.
* Class representing simple change of collection like insertion, remove or replacing/changing items.
*
* @param <TItem> Type of changing collection's items.
*/
public class Change<TItem> {
/**
* Method to calculate changes between two collections.
*
* @param initialCollection Initial collection;
* @param modifiedCollection Changed collection;
* @param shrinkChangesToModifiedSize Flag to make position of changed items be less then modified collection size.
* It is needed sometimes to not get exceptions like {@link ArrayIndexOutOfBoundsException}.
* @param <TItem> Type of collections items.
* @return Changes between collections.
*/
@NonNull
public static <TItem> Collection<Change<TItem>> calculateCollectionChanges(@NonNull final Collection<TItem> initialCollection,
@NonNull final Collection<TItem> modifiedCollection,
final boolean shrinkChangesToModifiedSize) {
return new CollectionsChangesCalculator<>(initialCollection, modifiedCollection, shrinkChangesToModifiedSize).calculateChanges();
}
@NonNull
private final Type type;
@NonNull
private final Collection<TItem> changedItems;
private final int start;
private final int count;
public Change(@NonNull final Type type, @NonNull final Collection<TItem> changedItems, final int start) {
this.type = type;
this.changedItems = Collections.unmodifiableCollection(new ArrayList<>(changedItems));
this.start = start;
this.count = changedItems.size();
}
/**
* Returns type of change.
*
* @return Type of change.
*/
@NonNull
public Type getType() {
return type;
}
/**
* Returns collection of items which this change applied to.
*
* @return Changed items.
*/
@NonNull
public Collection<TItem> getChangedItems() {
return changedItems;
}
/**
* Returns first index of changed item.
*
* @return Start of change.
*/
public int getStart() {
return start;
}
/**
* Returns count of changed items.
*
* @return Count of changed items.
*/
public int getCount() {
return count;
}
@NonNull
@Override
public String toString() {
return type + " change of " + start + ":" + count;
}
/**
* Type of change.
*/
public enum Type {
INSERTED,
CHANGED,
REMOVED
}
private static class CollectionsChangesCalculator<TItem> {
@NonNull
private final Collection<TItem> initialCollection;
@NonNull
private final Collection<TItem> modifiedCollection;
private final boolean shrinkChangesToModifiedSize;
private int initialOffset;
@NonNull
private final Collection<TItem> itemsToAdd = new ArrayList<>();
private int currentSize;
private int oldSize;
private int newSize;
private int couldBeAdded;
public CollectionsChangesCalculator(@NonNull final Collection<TItem> initialCollection,
@NonNull final Collection<TItem> modifiedCollection,
final boolean shrinkChangesToModifiedSize) {
this.initialCollection = initialCollection;
this.modifiedCollection = modifiedCollection;
this.shrinkChangesToModifiedSize = shrinkChangesToModifiedSize;
}
@NonNull
public Collection<Change<TItem>> calculateChanges() {
initialOffset = 0;
itemsToAdd.clear();
currentSize = 0;
oldSize = initialCollection.size();
newSize = modifiedCollection.size();
couldBeAdded = modifiedCollection.size() - initialCollection.size();
final List<Change<TItem>> result = new ArrayList<>();
for (final TItem modifiedItem : modifiedCollection) {
int foundPosition = 0;
for (final Object initialObject : initialCollection) {
if (foundPosition >= initialOffset && modifiedItem.equals(initialObject)) {
if (tryAddSkipped(result) == MethodAction.RETURN
|| tryRemoveRest(result, initialOffset, foundPosition - initialOffset) == MethodAction.RETURN) {
return result;
}
initialOffset = foundPosition + 1;
currentSize++;
break;
}
foundPosition++;
}
// if not found
if (foundPosition >= initialCollection.size()) {
itemsToAdd.add(modifiedItem);
}
}
if (tryAddSkipped(result) == MethodAction.RETURN) {
return result;
}
tryRemoveRest(result, initialOffset, initialCollection.size() - initialOffset);
return result;
}
@NonNull
private MethodAction tryAddSkipped(@NonNull final Collection<Change<TItem>> changes) {
if (!itemsToAdd.isEmpty()) {
if (shrinkChangesToModifiedSize && couldBeAdded < itemsToAdd.size()) {
addSimpleDifferenceChanges(changes);
return MethodAction.RETURN;
}
changes.add(new Change<>(Type.INSERTED, itemsToAdd, currentSize));
currentSize += itemsToAdd.size();
couldBeAdded -= itemsToAdd.size();
itemsToAdd.clear();
}
return MethodAction.CONTINUE;
}
@NonNull
private MethodAction tryRemoveRest(@NonNull final Collection<Change<TItem>> changes,
final int initialOffset,
final int itemsToRemove) {
if (itemsToRemove > 0) {
if (shrinkChangesToModifiedSize && couldBeAdded < -itemsToRemove) {
addSimpleDifferenceChanges(changes);
return MethodAction.RETURN;
}
changes.add(new Change<>(Change.Type.REMOVED,
new ArrayList<>(initialCollection).subList(initialOffset, initialOffset + itemsToRemove),
currentSize));
}
return MethodAction.CONTINUE;
}
private void addSimpleDifferenceChanges(@NonNull final Collection<Change<TItem>> changes) {
changes.add(new Change<>(Type.CHANGED, new ArrayList<>(modifiedCollection).subList(currentSize, newSize), currentSize));
if (oldSize - newSize > 0) {
changes.add(new Change<>(Type.REMOVED, new ArrayList<>(initialCollection).subList(newSize, oldSize), newSize));
}
}
private enum MethodAction {
RETURN,
CONTINUE
}
}
}

64
src/main/java/ru/touchin/roboswag/core/observables/collections/ObservableCollection.java
View File

@ -27,7 +27,10 @@ import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import ru.touchin.roboswag.core.observables.collections.changes.Change;
import ru.touchin.roboswag.core.observables.collections.changes.CollectionChanges;
import rx.Emitter;
import rx.Observable;
@ -43,11 +46,11 @@ public abstract class ObservableCollection<TItem> {
private int changesCount;
@NonNull
private transient Observable<CollectionChange<TItem>> changesObservable;
private transient Observable<CollectionChanges<TItem>> changesObservable;
@NonNull
private transient Observable<Collection<TItem>> itemsObservable;
@Nullable
private transient Emitter<? super CollectionChange<TItem>> changesEmitter;
private transient Emitter<? super CollectionChanges<TItem>> changesEmitter;
public ObservableCollection() {
this.changesObservable = createChangesObservable();
@ -55,9 +58,9 @@ public abstract class ObservableCollection<TItem> {
}
@NonNull
private Observable<CollectionChange<TItem>> createChangesObservable() {
private Observable<CollectionChanges<TItem>> createChangesObservable() {
return Observable
.<CollectionChange<TItem>>create(emitter -> this.changesEmitter = emitter, Emitter.BackpressureMode.BUFFER)
.<CollectionChanges<TItem>>create(emitter -> this.changesEmitter = emitter, Emitter.BackpressureMode.BUFFER)
.doOnUnsubscribe(() -> this.changesEmitter = null)
.share();
}
@ -85,22 +88,28 @@ public abstract class ObservableCollection<TItem> {
*
* @param change Change of collection.
*/
protected void notifyAboutChange(@NonNull final Change<TItem> change) {
notifyAboutChanges(Collections.singleton(change));
protected void notifyAboutChange(@NonNull final List<TItem> insertedItems,
@NonNull final List<TItem> removedItems,
@NonNull final Change change) {
notifyAboutChanges(insertedItems, removedItems, Collections.singleton(change));
}
/**
* Method to notify that collection have changed.
*
* @param insertedItems Collection of inserted items;
* @param removedItems Collection of removed items;
* @param changes Changes of collection.
*/
protected void notifyAboutChanges(@NonNull final Collection<Change<TItem>> changes) {
protected void notifyAboutChanges(@NonNull final List<TItem> insertedItems,
@NonNull final List<TItem> removedItems,
@NonNull final Collection<Change> changes) {
if (changes.isEmpty()) {
return;
}
changesCount++;
if (changesEmitter != null) {
changesEmitter.onNext(new CollectionChange<>(changesCount, Collections.unmodifiableCollection(changes)));
changesEmitter.onNext(new CollectionChanges<>(changesCount, insertedItems, removedItems, changes));
}
}
@ -110,7 +119,7 @@ public abstract class ObservableCollection<TItem> {
* @return List of changes applied to collection.
*/
@NonNull
public Observable<CollectionChange<TItem>> observeChanges() {
public Observable<CollectionChanges<TItem>> observeChanges() {
return changesObservable;
}
@ -170,41 +179,4 @@ public abstract class ObservableCollection<TItem> {
this.itemsObservable = createItemsObservable();
}
/**
* Class which is representing change of collection. There could be multiple changes applied to collection.
*
* @param <TItem> Type of collection's items.
*/
public static class CollectionChange<TItem> {
private final int number;
@NonNull
private final Collection<Change<TItem>> changes;
protected CollectionChange(final int number, @NonNull final Collection<Change<TItem>> changes) {
this.number = number;
this.changes = changes;
}
/**
* Returns number of change.
*
* @return Number of change.
*/
public int getNumber() {
return number;
}
/**
* Returns collection of changes.
*
* @return Collection of changes.
*/
@NonNull
public Collection<Change<TItem>> getChanges() {
return changes;
}
}
}

13
src/main/java/ru/touchin/roboswag/core/observables/collections/ObservableFilteredList.java
View File

@ -9,6 +9,7 @@ import java.util.Collections;
import java.util.List;
import java.util.concurrent.Executors;
import ru.touchin.roboswag.core.observables.collections.changes.DefaultCollectionsChangesCalculator;
import rx.Scheduler;
import rx.Subscription;
import rx.functions.Func1;
@ -23,6 +24,9 @@ import rx.schedulers.Schedulers;
*/
public class ObservableFilteredList<TItem> extends ObservableCollection<TItem> {
// we need to filter on 1 thread to prevent parallel filtering
private static final Scheduler FILTER_SCHEDULER = Schedulers.from(Executors.newSingleThreadExecutor());
@NonNull
private static <TItem> List<TItem> filterCollection(@NonNull final Collection<TItem> sourceCollection,
@Nullable final Func1<TItem, Boolean> filter) {
@ -38,9 +42,6 @@ public class ObservableFilteredList<TItem> extends ObservableCollection<TItem> {
return result;
}
// we need to filter on 1 thread to prevent parallel filtering
@NonNull
private final Scheduler filterScheduler = Schedulers.from(Executors.newSingleThreadExecutor());
@NonNull
private List<TItem> filteredList;
@NonNull
@ -106,11 +107,13 @@ public class ObservableFilteredList<TItem> extends ObservableCollection<TItem> {
sourceCollectionSubscription = null;
}
sourceCollectionSubscription = sourceCollection.observeItems()
.observeOn(filterScheduler)
.observeOn(FILTER_SCHEDULER)
.subscribe(items -> {
final List<TItem> oldFilteredList = filteredList;
filteredList = filterCollection(items, filter);
notifyAboutChanges(Change.calculateCollectionChanges(oldFilteredList, filteredList, false));
final DefaultCollectionsChangesCalculator<TItem> calculator
= new DefaultCollectionsChangesCalculator<>(oldFilteredList, filteredList, false);
notifyAboutChanges(calculator.calculateInsertedItems(), calculator.calculateRemovedItems(), calculator.calculateChanges());
});
}

70
src/main/java/ru/touchin/roboswag/core/observables/collections/ObservableList.java
View File

@ -20,6 +20,7 @@
package ru.touchin.roboswag.core.observables.collections;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import java.io.IOException;
import java.io.ObjectInputStream;
@ -31,6 +32,12 @@ import java.util.Collections;
import java.util.List;
import ru.touchin.roboswag.core.log.Lc;
import ru.touchin.roboswag.core.observables.collections.changes.Change;
import ru.touchin.roboswag.core.observables.collections.changes.ChangePayloadProducer;
import ru.touchin.roboswag.core.observables.collections.changes.CollectionsChangesCalculator;
import ru.touchin.roboswag.core.observables.collections.changes.DefaultCollectionsChangesCalculator;
import ru.touchin.roboswag.core.observables.collections.changes.DiffCollectionsChangesCalculator;
import ru.touchin.roboswag.core.observables.collections.changes.SameItemsPredicate;
/**
* Created by Gavriil Sitnikov on 23/05/16.
@ -46,6 +53,11 @@ public class ObservableList<TItem> extends ObservableCollection<TItem> implement
@NonNull
private List<TItem> items;
private boolean detectMoves;
@Nullable
private SameItemsPredicate<TItem> sameItemsPredicate;
@Nullable
private ChangePayloadProducer<TItem> changePayloadProducer;
public ObservableList() {
super();
@ -75,7 +87,7 @@ public class ObservableList<TItem> extends ObservableCollection<TItem> implement
public void add(final int position, @NonNull final TItem item) {
synchronized (this) {
items.add(position, item);
notifyAboutChange(new Change<>(Change.Type.INSERTED, Collections.singleton(item), position));
notifyAboutChange(Collections.singletonList(item), Collections.emptyList(), new Change.Inserted(position, 1));
}
}
@ -98,7 +110,7 @@ public class ObservableList<TItem> extends ObservableCollection<TItem> implement
synchronized (this) {
if (!itemsToAdd.isEmpty()) {
items.addAll(position, itemsToAdd);
notifyAboutChange(new Change<>(Change.Type.INSERTED, itemsToAdd, position));
notifyAboutChange(new ArrayList<>(itemsToAdd), Collections.emptyList(), new Change.Inserted(position, itemsToAdd.size()));
}
}
}
@ -139,12 +151,11 @@ public class ObservableList<TItem> extends ObservableCollection<TItem> implement
return;
}
synchronized (this) {
final List<TItem> changedItems = new ArrayList<>(count);
final List<TItem> removedItems = new ArrayList<>(count);
for (int i = 0; i < count; i++) {
changedItems.add(items.get(position));
items.remove(position);
removedItems.add(items.remove(position));
}
notifyAboutChange(new Change<>(Change.Type.REMOVED, changedItems, position));
notifyAboutChange(Collections.emptyList(), removedItems, new Change.Removed(position, count));
}
}
@ -153,10 +164,10 @@ public class ObservableList<TItem> extends ObservableCollection<TItem> implement
*/
public void clear() {
synchronized (this) {
final Change<TItem> change = new Change<>(Change.Type.REMOVED, items, 0);
if (!change.getChangedItems().isEmpty()) {
if (!items.isEmpty()) {
final List<TItem> removedItems = new ArrayList<>(items);
items.clear();
notifyAboutChange(change);
notifyAboutChange(Collections.emptyList(), removedItems, new Change.Removed(0, removedItems.size()));
}
}
}
@ -203,7 +214,7 @@ public class ObservableList<TItem> extends ObservableCollection<TItem> implement
items.set(index, item);
index++;
}
notifyAboutChange(new Change<>(Change.Type.CHANGED, updatedItems, position));
notifyAboutChange(Collections.emptyList(), Collections.emptyList(), new Change.Changed(position, updatedItems.size(), null));
}
}
@ -214,10 +225,14 @@ public class ObservableList<TItem> extends ObservableCollection<TItem> implement
*/
public void set(@NonNull final Collection<TItem> newItems) {
synchronized (this) {
final Collection<Change<TItem>> changes = Change.calculateCollectionChanges(items, newItems, false);
final List<TItem> oldList = new ArrayList<>(items);
final List<TItem> newList = new ArrayList<>(newItems);
final CollectionsChangesCalculator<TItem> calculator = sameItemsPredicate != null
? new DiffCollectionsChangesCalculator<>(oldList, newList, detectMoves, sameItemsPredicate, changePayloadProducer)
: new DefaultCollectionsChangesCalculator<>(oldList, newList, false);
items.clear();
items.addAll(newItems);
notifyAboutChanges(changes);
notifyAboutChanges(calculator.calculateInsertedItems(), calculator.calculateRemovedItems(), calculator.calculateChanges());
}
}
@ -228,6 +243,37 @@ public class ObservableList<TItem> extends ObservableCollection<TItem> implement
}
}
/**
* Enable diff utils algorithm in collection changes.
*
* @param detectMoves The flag that determines whether the {@link Change.Moved} changes will be generated or not;
* @param sameItemsPredicate Predicate for the determination of the same elements;
* @param changePayloadProducer Function that calculate change payload when items the same but contents are different.
*/
public void enableDiffUtils(final boolean detectMoves,
@NonNull final SameItemsPredicate<TItem> sameItemsPredicate,
@Nullable final ChangePayloadProducer<TItem> changePayloadProducer) {
this.detectMoves = detectMoves;
this.sameItemsPredicate = sameItemsPredicate;
this.changePayloadProducer = changePayloadProducer;
}
/**
* Disable diff utils algorithm.
*/
public void disableDiffUtils() {
this.sameItemsPredicate = null;
}
/**
* Returns enabled flag of diff utils.
*
* @return true if diff utils is enabled.
*/
public boolean diffUtilsIsEnabled() {
return sameItemsPredicate != null;
}
/**
* Returns position of item in list.
*

134
src/main/java/ru/touchin/roboswag/core/observables/collections/changes/Change.java Normal file
View File

@ -0,0 +1,134 @@
/*
* Copyright (c) 2015 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
*
* This file is part of RoboSwag library.
*
* 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 ru.touchin.roboswag.core.observables.collections.changes;
import android.support.annotation.Nullable;
/**
* Created by Gavriil Sitnikov on 23/05/16.
* Class representing simple change of collection like insertion, remove or replacing/changing items.
*/
public abstract class Change {
/**
* Represents a insert operation in collection.
*/
public static class Inserted extends Change {
private final int position;
private final int count;
public Inserted(final int position, final int count) {
super();
this.position = position;
this.count = count;
}
public int getPosition() {
return position;
}
public int getCount() {
return count;
}
}
/**
* Represents a remove operation from collection.
*/
public static class Removed extends Change {
private final int position;
private final int count;
public Removed(final int position, final int count) {
super();
this.position = position;
this.count = count;
}
public int getPosition() {
return position;
}
public int getCount() {
return count;
}
}
/**
* Represents a move operation in collection.
*/
public static class Moved extends Change {
private final int fromPosition;
private final int toPosition;
public Moved(final int fromPosition, final int toPosition) {
super();
this.fromPosition = fromPosition;
this.toPosition = toPosition;
}
public int getFromPosition() {
return fromPosition;
}
public int getToPosition() {
return toPosition;
}
}
/**
* Represents a modification operation in a collection.
*/
public static class Changed extends Change {
private final int position;
private final int count;
@Nullable
private final Object payload;
public Changed(final int position, final int count, @Nullable final Object payload) {
super();
this.position = position;
this.count = count;
this.payload = payload;
}
public int getPosition() {
return position;
}
public int getCount() {
return count;
}
@Nullable
public Object getPayload() {
return payload;
}
}
}

30
src/main/java/ru/touchin/roboswag/core/observables/collections/changes/ChangePayloadProducer.java Normal file
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@ -0,0 +1,30 @@
/*
* Copyright (c) 2017 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
*
* This file is part of RoboSwag library.
*
* 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 ru.touchin.roboswag.core.observables.collections.changes;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
public interface ChangePayloadProducer<TItem> {
@Nullable
Object getChangePayload(@NonNull TItem item1, @NonNull TItem item2);
}

90
src/main/java/ru/touchin/roboswag/core/observables/collections/changes/CollectionChanges.java Normal file
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@ -0,0 +1,90 @@
/*
* Copyright (c) 2017 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
*
* This file is part of RoboSwag library.
*
* 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 ru.touchin.roboswag.core.observables.collections.changes;
import android.support.annotation.NonNull;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
/**
* Class which is representing change of collection. There could be multiple changes applied to collection.
*/
public class CollectionChanges<TItem> {
private final int number;
@NonNull
private final List<TItem> insertedItems;
@NonNull
private final List<TItem> removedItems;
@NonNull
private final Collection<Change> changes;
public CollectionChanges(final int number,
@NonNull final List<TItem> insertedItems,
@NonNull final List<TItem> removedItems,
@NonNull final Collection<Change> changes) {
this.number = number;
this.insertedItems = Collections.unmodifiableList(insertedItems);
this.removedItems = Collections.unmodifiableList(removedItems);
this.changes = Collections.unmodifiableCollection(changes);
}
/**
* Returns number of change.
*
* @return Number of change.
*/
public int getNumber() {
return number;
}
/**
* Returns collection of changes.
*
* @return Collection of changes.
*/
@NonNull
public Collection<Change> getChanges() {
return changes;
}
/**
* Returns inserted items in change.
*
* @return Inserted items.
*/
@NonNull
public List<TItem> getInsertedItems() {
return insertedItems;
}
/**
* Returns removed items in change.
*
* @return Removed items.
*/
@NonNull
public List<TItem> getRemovedItems() {
return removedItems;
}
}

37
src/main/java/ru/touchin/roboswag/core/observables/collections/changes/CollectionsChangesCalculator.java Normal file
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@ -0,0 +1,37 @@
/*
* Copyright (c) 2017 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
*
* This file is part of RoboSwag library.
*
* 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 ru.touchin.roboswag.core.observables.collections.changes;
import android.support.annotation.NonNull;
import java.util.List;
public interface CollectionsChangesCalculator<TItem> {
@NonNull
List<Change> calculateChanges();
@NonNull
List<TItem> calculateInsertedItems();
@NonNull
List<TItem> calculateRemovedItems();
}

159
src/main/java/ru/touchin/roboswag/core/observables/collections/changes/DefaultCollectionsChangesCalculator.java Normal file
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@ -0,0 +1,159 @@
/*
* Copyright (c) 2017 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
*
* This file is part of RoboSwag library.
*
* 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 ru.touchin.roboswag.core.observables.collections.changes;
import android.support.annotation.NonNull;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
public class DefaultCollectionsChangesCalculator<TItem> implements CollectionsChangesCalculator<TItem> {
@NonNull
private final Collection<TItem> initialCollection;
@NonNull
private final Collection<TItem> modifiedCollection;
private final boolean shrinkChangesToModifiedSize;
@NonNull
private final Collection<TItem> itemsToAdd = new ArrayList<>();
private int currentSize;
private int oldSize;
private int newSize;
private int couldBeAdded;
/**
* Default calculator of changes between two collections.
*
* @param initialCollection Initial collection;
* @param modifiedCollection Changed collection;
* @param shrinkChangesToModifiedSize Flag to make position of changed items be less then modified collection size.
* It is needed sometimes to not get exceptions like {@link ArrayIndexOutOfBoundsException}.
*/
public DefaultCollectionsChangesCalculator(@NonNull final Collection<TItem> initialCollection,
@NonNull final Collection<TItem> modifiedCollection,
final boolean shrinkChangesToModifiedSize) {
super();
this.initialCollection = initialCollection;
this.modifiedCollection = modifiedCollection;
this.shrinkChangesToModifiedSize = shrinkChangesToModifiedSize;
}
@NonNull
@Override
public List<Change> calculateChanges() {
int initialOffset = 0;
itemsToAdd.clear();
currentSize = 0;
oldSize = initialCollection.size();
newSize = modifiedCollection.size();
couldBeAdded = modifiedCollection.size() - initialCollection.size();
final List<Change> result = new ArrayList<>();
for (final TItem modifiedItem : modifiedCollection) {
int foundPosition = 0;
for (final Object initialObject : initialCollection) {
if (foundPosition >= initialOffset && modifiedItem.equals(initialObject)) {
if (tryAddSkipped(result) == MethodAction.RETURN
|| tryRemoveRest(result, foundPosition - initialOffset) == MethodAction.RETURN) {
return result;
}
initialOffset = foundPosition + 1;
currentSize++;
break;
}
foundPosition++;
}
// if not found
if (foundPosition >= initialCollection.size()) {
itemsToAdd.add(modifiedItem);
}
}
if (tryAddSkipped(result) == MethodAction.RETURN) {
return result;
}
tryRemoveRest(result, initialCollection.size() - initialOffset);
return result;
}
@NonNull
@Override
public List<TItem> calculateInsertedItems() {
final List<TItem> insertedItems = new ArrayList<>();
for (final TItem newItem : modifiedCollection) {
if (!initialCollection.contains(newItem)) {
insertedItems.add(newItem);
}
}
return insertedItems;
}
@NonNull
@Override
public List<TItem> calculateRemovedItems() {
final List<TItem> removedItems = new ArrayList<>();
for (final TItem oldItem : initialCollection) {
if (!modifiedCollection.contains(oldItem)) {
removedItems.add(oldItem);
}
}
return removedItems;
}
@NonNull
private MethodAction tryAddSkipped(@NonNull final Collection<Change> changes) {
if (!itemsToAdd.isEmpty()) {
if (shrinkChangesToModifiedSize && couldBeAdded < itemsToAdd.size()) {
addSimpleDifferenceChanges(changes);
return MethodAction.RETURN;
}
changes.add(new Change.Inserted(currentSize, itemsToAdd.size()));
currentSize += itemsToAdd.size();
couldBeAdded -= itemsToAdd.size();
itemsToAdd.clear();
}
return MethodAction.CONTINUE;
}
@NonNull
private MethodAction tryRemoveRest(@NonNull final Collection<Change> changes, final int itemsToRemove) {
if (itemsToRemove > 0) {
if (shrinkChangesToModifiedSize && couldBeAdded < -itemsToRemove) {
addSimpleDifferenceChanges(changes);
return MethodAction.RETURN;
}
changes.add(new Change.Removed(currentSize, itemsToRemove));
}
return MethodAction.CONTINUE;
}
private void addSimpleDifferenceChanges(@NonNull final Collection<Change> changes) {
changes.add(new Change.Changed(currentSize, newSize - currentSize, null));
if (oldSize - newSize > 0) {
changes.add(new Change.Removed(newSize, oldSize - newSize));
}
}
private enum MethodAction {
RETURN,
CONTINUE
}
}

144
src/main/java/ru/touchin/roboswag/core/observables/collections/changes/DiffCollectionsChangesCalculator.java Normal file
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@ -0,0 +1,144 @@
/*
* Copyright (c) 2017 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
*
* This file is part of RoboSwag library.
*
* 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 ru.touchin.roboswag.core.observables.collections.changes;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import java.util.ArrayList;
import java.util.List;
import ru.touchin.roboswag.core.android.support.v7.util.DiffUtil;
import ru.touchin.roboswag.core.android.support.v7.util.ListUpdateCallback;
public class DiffCollectionsChangesCalculator<TItem> extends DiffUtil.Callback implements CollectionsChangesCalculator<TItem> {
@NonNull
private final List<TItem> oldList;
@NonNull
private final List<TItem> newList;
private final boolean detectMoves;
@NonNull
private final SameItemsPredicate<TItem> sameItemsPredicate;
@Nullable
private final ChangePayloadProducer<TItem> changePayloadProducer;
public DiffCollectionsChangesCalculator(@NonNull final List<TItem> oldList,
@NonNull final List<TItem> newList,
final boolean detectMoves,
@NonNull final SameItemsPredicate<TItem> sameItemsPredicate,
@Nullable final ChangePayloadProducer<TItem> changePayloadProducer) {
super();
this.oldList = oldList;
this.newList = newList;
this.detectMoves = detectMoves;
this.sameItemsPredicate = sameItemsPredicate;
this.changePayloadProducer = changePayloadProducer;
}
@NonNull
@Override
public List<Change> calculateChanges() {
final List<Change> changes = new ArrayList<>();
DiffUtil.calculateDiff(this, detectMoves).dispatchUpdatesTo(new ListUpdateCallback() {
@Override
public void onInserted(final int position, final int count) {
changes.add(new Change.Inserted(position, count));
}
@Override
public void onRemoved(final int position, final int count) {
changes.add(new Change.Removed(position, count));
}
@Override
public void onMoved(final int fromPosition, final int toPosition) {
changes.add(new Change.Moved(fromPosition, toPosition));
}
@Override
public void onChanged(final int position, final int count, @Nullable final Object payload) {
changes.add(new Change.Changed(position, count, payload));
}
});
return changes;
}
@NonNull
@Override
public List<TItem> calculateInsertedItems() {
final List<TItem> insertedItems = new ArrayList<>();
for (final TItem newItem : newList) {
if (!containsByPredicate(newItem, oldList)) {
insertedItems.add(newItem);
}
}
return insertedItems;
}
@NonNull
@Override
public List<TItem> calculateRemovedItems() {
final List<TItem> removedItems = new ArrayList<>();
for (final TItem oldItem : oldList) {
if (!containsByPredicate(oldItem, newList)) {
removedItems.add(oldItem);
}
}
return removedItems;
}
@Override
public int getOldListSize() {
return oldList.size();
}
@Override
public int getNewListSize() {
return newList.size();
}
@Override
public boolean areItemsTheSame(final int oldItemPosition, final int newItemPosition) {
return sameItemsPredicate.areSame(oldList.get(oldItemPosition), newList.get(newItemPosition));
}
@Override
public boolean areContentsTheSame(final int oldItemPosition, final int newItemPosition) {
return oldList.get(oldItemPosition).equals(newList.get(newItemPosition));
}
@Nullable
@Override
public Object getChangePayload(final int oldItemPosition, final int newItemPosition) {
return changePayloadProducer != null
? changePayloadProducer.getChangePayload(oldList.get(oldItemPosition), newList.get(newItemPosition)) : null;
}
private boolean containsByPredicate(@NonNull final TItem searchedItem, @NonNull final List<TItem> items) {
for (final TItem item : items) {
if (sameItemsPredicate.areSame(item, searchedItem)) {
return true;
}
}
return false;
}
}

28
src/main/java/ru/touchin/roboswag/core/observables/collections/changes/SameItemsPredicate.java Normal file
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@ -0,0 +1,28 @@
/*
* Copyright (c) 2017 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
*
* This file is part of RoboSwag library.
*
* 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 ru.touchin.roboswag.core.observables.collections.changes;
import android.support.annotation.NonNull;
public interface SameItemsPredicate<TItem> {
boolean areSame(@NonNull TItem item1, @NonNull TItem item2);
}

9
src/main/java/ru/touchin/roboswag/core/observables/collections/loadable/LoadingMoreList.java
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@ -30,9 +30,10 @@ import java.util.NoSuchElementException;
import java.util.concurrent.Executors;
import ru.touchin.roboswag.core.log.Lc;
import ru.touchin.roboswag.core.observables.collections.Change;
import ru.touchin.roboswag.core.observables.collections.ObservableCollection;
import ru.touchin.roboswag.core.observables.collections.ObservableList;
import ru.touchin.roboswag.core.observables.collections.changes.Change;
import ru.touchin.roboswag.core.observables.collections.changes.CollectionChanges;
import ru.touchin.roboswag.core.utils.ShouldNotHappenException;
import rx.Observable;
import rx.Scheduler;
@ -135,12 +136,14 @@ public class LoadingMoreList<TItem, TMoreReference, TLoadedItems extends LoadedI
@NonNull
@Override
public Observable<CollectionChange<TItem>> observeChanges() {
public Observable<CollectionChanges<TItem>> observeChanges() {
return innerList.observeChanges();
}
@Override
protected void notifyAboutChanges(@NonNull final Collection<Change<TItem>> changes) {
protected void notifyAboutChanges(@NonNull final List<TItem> insertedItems,
@NonNull final List<TItem> removedItems,
@NonNull final Collection<Change> changes) {
Lc.assertion("Illegal operation. Modify getInnerList()");
}