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// Copyright 2015 The Bazel Authors. 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
//
// 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.
#import "Equation.h"
@implementation Equation {
NSMutableArray *_children;
}
@synthesize operation = _operation;
- (id)init {
[self doesNotRecognizeSelector:_cmd];
return nil;
}
- (id)initWithOperation:(Operation)operation {
self = [super init];
if (self) {
_children = [NSMutableArray array];
_operation = operation;
}
return self;
}
- (NSArray *)children {
return [_children copy];
}
- (void)addExpressionAsChild:(Expression *)child {
[_children addObject:child];
}
- (double)calculate {
if ([_children count] == 1) {
return (_operation == kSubtract)
? -[_children[0] calculate] : [_children[0] calculate];
} else if ([_children count] == 0) {
return (_operation == kSubtract || _operation == kAdd) ? 0 : 1;
}
double value = [_children[0] calculate];
for (Equation *child in [_children subarrayWithRange:
NSMakeRange(1, [_children count] - 1)]) {
double childValue = [child calculate];
switch (_operation) {
case kAdd:
value += childValue;
break;
case kSubtract:
value -= childValue;
break;
case kMultiply:
value *= childValue;
break;
case kDivide:
value /= childValue;
break;
}
}
return value;
}
- (NSString *)description {
NSMutableString *result = [[NSMutableString alloc] init];
[result appendString:@"("];
switch (_operation) {
case kAdd:
[result appendString:@"+"];
break;
case kSubtract:
[result appendString:@"-"];
break;
case kMultiply:
[result appendString:@"*"];
break;
case kDivide:
[result appendString:@"/"];
break;
}
for (Equation *child in _children) {
[result appendString:@" "];
[result appendString:[child description]];
}
[result appendString:@")"];
return [result copy];
}
- (BOOL)isEqual:(id)object {
if (![object isKindOfClass:[self class]]) {
return NO;
}
Equation *other = object;
return other->_operation == _operation &&
[other->_children isEqual:_children];
}
@end
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