2019-11-11 16:39:27 +04:00

93 lines
3.6 KiB
Objective-C

//
// NSArray+Diffing.h
// Texture
//
// Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
// Changes after 4/13/2017 are: Copyright (c) Pinterest, Inc. All rights reserved.
// Licensed under Apache 2.0: http://www.apache.org/licenses/LICENSE-2.0
//
#import <Foundation/Foundation.h>
/**
* These changes can be used to transform `self` to `array` by applying them in (any) order, *without shifting* the
* other elements. This can be done (in an NSMutableArray) by calling `setObject:atIndexedSubscript:` (or just use
* [subscripting] directly) for insertions from `array` into `self` (not the seemingly more apt `insertObject:atIndex`!),
* and using the same method for deletions from `self` (*set* a `[NSNull null]` as opposed to `removeObject:atIndex:`).
* After all inserts/deletes have been applied, there will be no nulls left (except possibly at the end of the array if
* `[array count] < [self count]`)
* Some examples:
* in: ab c
* out: abdc
* diff: ..+.
*
* in: abcd
* out: dcba
* dif: ---.+++
*
* in: abcd
* out: ab d
* diff: ..-.
*
* in: a bcd
* out: adbc
* diff: .+..-
*
* If `moves` pointer is passed in, instances where one element moves to another location are detected and reported,
* possibly replacing pairs of delete/insert. The process for transforming an array remains the same, however now it is
* important to apply the moves in order and not overwrite an element that needs to be moved somewhere else.
*
* the same examples, with moves:
* in: ab c
* out: abdc
* diff: ..+.
*
* in: abcd
* out: dcba
* diff: 321.
*
* in: abcd
* out: ab d
* diff: ..-.
*
* in: abcd
* out: adbc
* diff: .312
*
* Other notes:
*
* No index will be both moved from and deleted.
* Each index 0...[self count] will be either moved from or deleted. If it is moved to the same location, we omit it.
* Each index 0...[array count] will be the destination of ONE move or ONE insert.
* Knowing these things means any two of the three (delete, move, insert) implies the third.
*/
@interface NSArray (Diffing)
/**
* @abstract Compares two arrays, providing the insertion and deletion indexes needed to transform into the target array.
* @discussion This compares the equality of each object with `isEqual:`.
* This diffing algorithm uses a bottom-up memoized longest common subsequence solution to identify differences.
* It runs in O(mn) complexity.
*/
- (void)asdk_diffWithArray:(NSArray *)array insertions:(NSIndexSet **)insertions deletions:(NSIndexSet **)deletions;
/**
* @abstract Compares two arrays, providing the insertion and deletion indexes needed to transform into the target array.
* @discussion The `compareBlock` is used to identify the equality of the objects within the arrays.
* This diffing algorithm uses a bottom-up memoized longest common subsequence solution to identify differences.
* It runs in O(mn) complexity.
*/
- (void)asdk_diffWithArray:(NSArray *)array insertions:(NSIndexSet **)insertions deletions:(NSIndexSet **)deletions compareBlock:(BOOL (^)(id lhs, id rhs))comparison;
/**
* @abstract Compares two arrays, providing the insertion, deletion, and move indexes needed to transform into the target array.
* @discussion This compares the equality of each object with `isEqual:`.
* This diffing algorithm uses a bottom-up memoized longest common subsequence solution to identify differences.
* It runs in O(mn) complexity.
* The moves are returned in ascending order of their destination index.
*/
- (void)asdk_diffWithArray:(NSArray *)array insertions:(NSIndexSet **)insertions deletions:(NSIndexSet **)deletions moves:(NSArray<NSIndexPath *> **)moves;
@end