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//
// SDLStateMachine.m
// SmartDeviceLink-iOS
//
// Created by Joel Fischer on 10/30/15.
// Copyright © 2015 smartdevicelink. All rights reserved.
//
#import "SDLStateMachine.h"
#import "SDLError.h"
NS_ASSUME_NONNULL_BEGIN
NSString *const SDLStateMachineNotificationFormat = @"com.sdl.statemachine.%@";
SDLStateMachineNotificationInfoKey const SDLStateMachineNotificationInfoKeyOldState = @"oldState";
SDLStateMachineNotificationInfoKey const SDLStateMachineNotificationInfoKeyNewState = @"newState";
SDLStateMachineExceptionInfoKey const SDLStateMachineExceptionInfoKeyTargetClass = @"targetClass";
SDLStateMachineExceptionInfoKey const SDLStateMachineExceptionInfoKeyFromState = @"fromState";
SDLStateMachineExceptionInfoKey const SDLStateMachineExceptionInfoKeyToClass = @"toState";
SDLStateMachineTransitionFormat const SDLStateMachineTransitionFormatWillLeave = @"willLeaveState%@";
SDLStateMachineTransitionFormat const SDLStateMachineTransitionFormatWillTransition = @"willTransitionFromState%@ToState%@";
SDLStateMachineTransitionFormat const SDLStateMachineTransitionFormatDidTransition = @"didTransitionFromState%@ToState%@";
SDLStateMachineTransitionFormat const SDLStateMachineTransitionFormatDidEnter = @"didEnterState%@";
@interface SDLStateMachine ()
@property (copy, nonatomic, readwrite) SDLState *currentState;
@end
@implementation SDLStateMachine
- (instancetype)initWithTarget:(id)target initialState:(SDLState *)initialState states:(NSDictionary<SDLState *, SDLAllowableStateTransitions *> *)states {
self = [super init];
if (!self) {
return nil;
}
if (states[initialState] == nil) {
@throw [NSException exceptionWithName:NSInternalInconsistencyException reason:@"Attempted to start with an SDLState that is not in the states dictionary" userInfo:nil];
}
_target = target;
_states = states;
_currentState = initialState;
return self;
}
- (void)transitionToState:(SDLState *)state {
NSString *oldState = [self.currentState copy];
if ([self isCurrentState:state]) {
return;
}
if (![self sdl_canState:self.currentState transitionToState:state]) {
@throw [NSException exceptionWithName:NSInternalInconsistencyException
reason:@"Invalid state machine transition occurred"
userInfo:@{SDLStateMachineExceptionInfoKeyTargetClass: NSStringFromClass([self.target class]),
SDLStateMachineExceptionInfoKeyFromState: self.currentState,
SDLStateMachineExceptionInfoKeyToClass: state}];
}
SEL willLeave = NSSelectorFromString([NSString stringWithFormat:SDLStateMachineTransitionFormatWillLeave, oldState]);
SEL willTransition = NSSelectorFromString([NSString stringWithFormat:SDLStateMachineTransitionFormatWillTransition, oldState, state]);
SEL didTransition = NSSelectorFromString([NSString stringWithFormat:SDLStateMachineTransitionFormatDidTransition, oldState, state]);
SEL didEnter = NSSelectorFromString([NSString stringWithFormat:SDLStateMachineTransitionFormatDidEnter, state]);
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
// Pre state transition calls
if ([self.target respondsToSelector:willLeave]) {
[self.target performSelector:willLeave];
}
if ([self.target respondsToSelector:willTransition]) {
[self.target performSelector:willTransition];
}
// Transition the state
self.currentState = state;
// Post state transition calls
[[NSNotificationCenter defaultCenter] postNotificationName:self.transitionNotificationName object:self userInfo:@{SDLStateMachineNotificationInfoKeyOldState: oldState, SDLStateMachineNotificationInfoKeyNewState: state}];
if ([self.target respondsToSelector:didTransition]) {
[self.target performSelector:didTransition];
}
if ([self.target respondsToSelector:didEnter]) {
[self.target performSelector:didEnter];
}
#pragma clang diagnostic pop
}
- (BOOL)isCurrentState:(SDLState *)state {
return [self.currentState isEqualToString:state];
}
#pragma mark - Helpers
- (void)setToState:(SDLState *)state fromOldState:(nullable SDLState *)oldState callEnterTransition:(BOOL)shouldCall {
if (![self.states.allKeys containsObject:state]) {
return;
}
if (oldState != nil && shouldCall) {
self.currentState = oldState;
[self transitionToState:state];
} else if (shouldCall) {
SEL didEnter = NSSelectorFromString([NSString stringWithFormat:SDLStateMachineTransitionFormatDidEnter, state]);
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
if ([self.target respondsToSelector:didEnter]) {
[self.target performSelector:didEnter];
#pragma clang diagnostic pop
}
} else {
self.currentState = state;
}
}
/**
* Determine if a state transition is valid. Returns YES if the state transition dictionary's fromState key contains toState in its value array, or if fromState and toState are the same state.
*
* @param fromState The former state
* @param toState The new state
*
* @return Whether or not the state transition is valid
*/
- (BOOL)sdl_canState:(SDLState *)fromState transitionToState:(SDLState *)toState {
if ([self.states[fromState] containsObject:toState] || [fromState isEqualToString:toState]) {
return YES;
}
return NO;
}
- (NSString *)transitionNotificationName {
return [NSString stringWithFormat:SDLStateMachineNotificationFormat, [self.target class]];
}
@end
NS_ASSUME_NONNULL_END
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