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Introduce ASIntegerMap, improve our changeset handling
Rename to ASIntegerMap License header
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Adlai Holler
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Jul 5, 2017
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,58 @@ | ||
| // | ||
| // ASIntegerMap.h | ||
| // Texture | ||
| // | ||
| // Copyright (c) 2017-present, Pinterest, Inc. All rights reserved. | ||
| // 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 | ||
| // | ||
|
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| #import <Foundation/Foundation.h> | ||
| #import <AsyncDisplayKit/ASBaseDefines.h> | ||
|
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| NS_ASSUME_NONNULL_BEGIN | ||
|
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| /** | ||
| * An objective-C wrapper for unordered_map. | ||
| */ | ||
| AS_SUBCLASSING_RESTRICTED | ||
| @interface ASIntegerMap : NSObject <NSCopying> | ||
|
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| /** | ||
| * Creates an map based on the specified update to an array. | ||
| * | ||
| * If oldCount is 0, returns the empty map. | ||
| * If deleted and inserted are empty, returns the identity map. | ||
| */ | ||
| + (ASIntegerMap *)mapForUpdateWithOldCount:(NSInteger)oldCount | ||
| deleted:(NSIndexSet *)deleted | ||
| inserted:(NSIndexSet *)inserted; | ||
|
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| /** | ||
| * A singleton that maps each integer to itself. Its inverse is itself. | ||
| */ | ||
| @property (class, atomic, readonly) ASIntegerMap *identityMap; | ||
|
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| /** | ||
| * A singleton that returns NSNotFound for all keys. Its inverse is itself. | ||
| */ | ||
| @property (class, atomic, readonly) ASIntegerMap *emptyMap; | ||
|
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| /** | ||
| * Retrieves the integer for a given key, or NSNotFound if the key is not found. | ||
| * | ||
| * @param key A key to lookup the value for. | ||
| */ | ||
| - (NSInteger)integerForKey:(NSInteger)key; | ||
|
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| /** | ||
| * Create and return a map with the inverse mapping. | ||
| */ | ||
| - (ASIntegerMap *)inverseMap; | ||
|
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| @end | ||
|
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| NS_ASSUME_NONNULL_END |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,156 @@ | ||
| // | ||
| // ASIntegerMap.mm | ||
| // Texture | ||
| // | ||
| // Copyright (c) 2017-present, Pinterest, Inc. All rights reserved. | ||
| // 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 | ||
| // | ||
|
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| #import "ASIntegerMap.h" | ||
| #import <unordered_map> | ||
| #import <NSIndexSet+ASHelpers.h> | ||
| #import <AsyncDisplayKit/ASObjectDescriptionHelpers.h> | ||
|
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| /** | ||
| * This is just a friendly Objective-C interface to unordered_map<NSInteger, NSInteger> | ||
| */ | ||
| @interface ASIntegerMap () <ASDescriptionProvider> | ||
| @end | ||
|
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| @implementation ASIntegerMap { | ||
| std::unordered_map<NSInteger, NSInteger> _map; | ||
| BOOL _isIdentity; | ||
| BOOL _isEmpty; | ||
| } | ||
|
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| #pragma mark - Singleton | ||
|
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| + (ASIntegerMap *)identityMap | ||
| { | ||
| static ASIntegerMap *identityMap; | ||
| static dispatch_once_t onceToken; | ||
| dispatch_once(&onceToken, ^{ | ||
| identityMap = [[ASIntegerMap alloc] init]; | ||
| identityMap->_isIdentity = YES; | ||
| }); | ||
| return identityMap; | ||
| } | ||
|
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| + (ASIntegerMap *)emptyMap | ||
| { | ||
| static ASIntegerMap *emptyMap; | ||
| static dispatch_once_t onceToken; | ||
| dispatch_once(&onceToken, ^{ | ||
| emptyMap = [[ASIntegerMap alloc] init]; | ||
| emptyMap->_isEmpty = YES; | ||
| }); | ||
| return emptyMap; | ||
| } | ||
|
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| + (ASIntegerMap *)mapForUpdateWithOldCount:(NSInteger)oldCount deleted:(NSIndexSet *)deletions inserted:(NSIndexSet *)insertions | ||
| { | ||
| if (oldCount == 0) { | ||
| return ASIntegerMap.emptyMap; | ||
| } | ||
|
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| if (deletions.count == 0 && insertions.count == 0) { | ||
| return ASIntegerMap.identityMap; | ||
| } | ||
|
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| ASIntegerMap *result = [[ASIntegerMap alloc] init]; | ||
| // Start with the old indexes | ||
| NSMutableIndexSet *indexes = [NSMutableIndexSet indexSetWithIndexesInRange:NSMakeRange(0, oldCount)]; | ||
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| // Descending order, shift deleted ranges left | ||
| [deletions enumerateRangesWithOptions:NSEnumerationReverse usingBlock:^(NSRange range, BOOL * _Nonnull stop) { | ||
| [indexes shiftIndexesStartingAtIndex:NSMaxRange(range) by:-range.length]; | ||
| }]; | ||
|
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| // Ascending order, shift inserted ranges right | ||
| [insertions enumerateRangesUsingBlock:^(NSRange range, BOOL * _Nonnull stop) { | ||
| [indexes shiftIndexesStartingAtIndex:range.location by:range.length]; | ||
| }]; | ||
|
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| __block NSInteger oldIndex = 0; | ||
| [indexes enumerateRangesUsingBlock:^(NSRange range, BOOL * _Nonnull stop) { | ||
| // Note we advance oldIndex unconditionally, not newIndex | ||
| for (NSInteger newIndex = range.location; newIndex < NSMaxRange(range); oldIndex++) { | ||
| if ([deletions containsIndex:oldIndex]) { | ||
| // index was deleted, do nothing, just let oldIndex advance. | ||
| } else { | ||
| // assign the next index for this item. | ||
| result->_map[oldIndex] = newIndex++; | ||
| } | ||
| } | ||
| }]; | ||
| return result; | ||
| } | ||
|
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| - (NSInteger)integerForKey:(NSInteger)key | ||
| { | ||
| if (_isIdentity) { | ||
| return key; | ||
| } else if (_isEmpty) { | ||
| return NSNotFound; | ||
| } | ||
|
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| auto result = _map.find(key); | ||
| return result != _map.end() ? result->second : NSNotFound; | ||
| } | ||
|
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| - (ASIntegerMap *)inverseMap | ||
| { | ||
| if (_isIdentity || _isEmpty) { | ||
| return self; | ||
| } | ||
|
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| auto result = [[ASIntegerMap alloc] init]; | ||
| for (auto it = _map.begin(); it != _map.end(); it++) { | ||
| result->_map[it->second] = it->first; | ||
| } | ||
| return result; | ||
| } | ||
|
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| #pragma mark - NSCopying | ||
|
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| - (id)copyWithZone:(NSZone *)zone | ||
| { | ||
| return self; | ||
| } | ||
|
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| #pragma mark - Description | ||
|
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| - (NSMutableArray<NSDictionary *> *)propertiesForDescription | ||
| { | ||
| NSMutableArray *result = [NSMutableArray array]; | ||
|
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| if (_isIdentity) { | ||
| [result addObject:@{ @"map": @"<identity>" }]; | ||
| } else if (_isEmpty) { | ||
| [result addObject:@{ @"map": @"<empty>" }]; | ||
| } else { | ||
| // { 1->2 3->4 5->6 } | ||
| NSMutableString *str = [NSMutableString string]; | ||
| for (auto it = _map.begin(); it != _map.end(); it++) { | ||
| [str appendFormat:@" %zd->%zd", it->first, it->second]; | ||
| } | ||
| // Remove leading space | ||
| if (str.length > 0) { | ||
| [str deleteCharactersInRange:NSMakeRange(0, 1)]; | ||
| } | ||
| [result addObject:@{ @"map": str }]; | ||
| } | ||
|
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| return result; | ||
| } | ||
|
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| - (NSString *)description | ||
| { | ||
| return ASObjectDescriptionMakeWithoutObject([self propertiesForDescription]); | ||
| } | ||
|
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| @end |
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