145 lines
3.9 KiB
Objective-C
145 lines
3.9 KiB
Objective-C
/*
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* Copyright 2017 Google
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#import "FSparseSnapshotTree.h"
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#import "FChildrenNode.h"
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@interface FSparseSnapshotTree () {
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id<FNode> value;
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NSMutableDictionary* children;
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}
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@end
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@implementation FSparseSnapshotTree
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- (id) init {
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self = [super init];
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if (self) {
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value = nil;
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children = nil;
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}
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return self;
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}
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- (id<FNode>) findPath:(FPath *)path {
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if (value != nil) {
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return [value getChild:path];
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} else if (![path isEmpty] && children != nil) {
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NSString* childKey = [path getFront];
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path = [path popFront];
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FSparseSnapshotTree* childTree = children[childKey];
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if (childTree != nil) {
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return [childTree findPath:path];
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} else {
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return nil;
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}
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} else {
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return nil;
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}
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}
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- (void) rememberData:(id<FNode>)data onPath:(FPath *)path {
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if ([path isEmpty]) {
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value = data;
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children = nil;
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} else if (value != nil) {
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value = [value updateChild:path withNewChild:data];
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} else {
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if (children == nil) {
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children = [[NSMutableDictionary alloc] init];
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}
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NSString* childKey = [path getFront];
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if (children[childKey] == nil) {
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children[childKey] = [[FSparseSnapshotTree alloc] init];
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}
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FSparseSnapshotTree* child = children[childKey];
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path = [path popFront];
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[child rememberData:data onPath:path];
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}
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}
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- (BOOL) forgetPath:(FPath *)path {
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if ([path isEmpty]) {
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value = nil;
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children = nil;
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return YES;
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} else {
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if (value != nil) {
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if ([value isLeafNode]) {
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// non-empty path at leaf. the path leads to nowhere
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return NO;
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} else {
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id<FNode> tmp = value;
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value = nil;
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[tmp enumerateChildrenUsingBlock:^(NSString *key, id<FNode> node, BOOL *stop) {
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[self rememberData:node onPath:[[FPath alloc] initWith:key]];
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}];
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// we've cleared out the value and set children. Call ourself again to hit the next case
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return [self forgetPath:path];
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}
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} else if (children != nil) {
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NSString* childKey = [path getFront];
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path = [path popFront];
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if (children[childKey] != nil) {
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FSparseSnapshotTree* child = children[childKey];
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BOOL safeToRemove = [child forgetPath:path];
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if (safeToRemove) {
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[children removeObjectForKey:childKey];
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}
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}
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if ([children count] == 0) {
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children = nil;
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return YES;
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} else {
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return NO;
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}
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} else {
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return YES;
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}
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}
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}
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- (void) forEachTreeAtPath:(FPath *)prefixPath do:(fbt_void_path_node)func {
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if (value != nil) {
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func(prefixPath, value);
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} else {
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[self forEachChild:^(NSString* key, FSparseSnapshotTree* tree) {
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FPath* path = [prefixPath childFromString:key];
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[tree forEachTreeAtPath:path do:func];
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}];
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}
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}
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- (void) forEachChild:(fbt_void_nsstring_sstree)func {
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if (children != nil) {
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for (NSString* key in children) {
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FSparseSnapshotTree* tree = [children objectForKey:key];
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func(key, tree);
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}
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}
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}
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@end
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