Add custom comparision block to array diffing category

This commit is contained in:
Levi McCallum
2016-02-01 15:31:46 -08:00
parent 9f25b54f9e
commit bd1de07c77
2 changed files with 23 additions and 5 deletions

View File

@@ -11,8 +11,19 @@
@interface NSArray (Diffing)
/**
* Uses a bottom-up memoized longest common subsequence solution to identify differences. Runs in O(mn) complexity.
* @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;
@end

View File

@@ -12,13 +12,20 @@
- (void)asdk_diffWithArray:(NSArray *)array insertions:(NSIndexSet **)insertions deletions:(NSIndexSet **)deletions
{
NSIndexSet *commonIndexes = [self _asdk_commonIndexesWithArray:array];
[self asdk_diffWithArray:array insertions:insertions deletions:deletions compareBlock:^BOOL(id lhs, id rhs) {
return [lhs isEqual:rhs];
}];
}
- (void)asdk_diffWithArray:(NSArray *)array insertions:(NSIndexSet **)insertions deletions:(NSIndexSet **)deletions compareBlock:(BOOL (^)(id lhs, id rhs))comparison
{
NSIndexSet *commonIndexes = [self _asdk_commonIndexesWithArray:array compareBlock:comparison];
if (insertions) {
NSArray *commonObjects = [self objectsAtIndexes:commonIndexes];
NSMutableIndexSet *insertionIndexes = [NSMutableIndexSet indexSet];
for (NSInteger i = 0, j = 0; i < commonObjects.count || j < array.count;) {
if (i < commonObjects.count && j < array.count && [commonObjects[i] isEqual:array[j]]) {
if (i < commonObjects.count && j < array.count && comparison(commonObjects[i], array[j])) {
i++; j++;
} else {
[insertionIndexes addIndex:j];
@@ -39,7 +46,7 @@
}
}
- (NSIndexSet *)_asdk_commonIndexesWithArray:(NSArray *)array
- (NSIndexSet *)_asdk_commonIndexesWithArray:(NSArray *)array compareBlock:(BOOL (^)(id lhs, id rhs))comparison
{
NSInteger lengths[self.count+1][array.count+1];
for (NSInteger i = self.count; i >= 0; i--) {
@@ -56,7 +63,7 @@
NSMutableIndexSet *common = [NSMutableIndexSet indexSet];
for (NSInteger i = 0, j = 0; i < self.count && j < array.count;) {
if ([self[i] isEqual:array[j]]) {
if (comparison(self[i], array[j])) {
[common addIndex:i];
i++; j++;
} else if (lengths[i+1][j] >= lengths[i][j+1]) {