Created
June 18, 2017 20:05
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Command Pattern
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| trait Command<T> { | |
| type Err; | |
| fn forward(&mut self, receiver: &mut T) -> Result<(), Self::Err>; | |
| fn backwards(&mut self, receiver: &mut T) -> Result<(), Self::Err>; | |
| } | |
| struct CommandStack<T, C: Command<T>>{ | |
| stack: Vec<C>, | |
| receiver: T, | |
| } | |
| impl<T, C: Command<T>> CommandStack<T, C> { | |
| fn new(receiver: T) -> CommandStack<T, C> { | |
| CommandStack { | |
| stack: Vec::new(), | |
| receiver: receiver, | |
| } | |
| } | |
| fn push(&mut self, mut command: C) -> Result<(), C::Err> { | |
| command.forward(&mut self.receiver)?; | |
| self.stack.push(command); | |
| Ok(()) | |
| } | |
| fn pop(&mut self) -> Option<Result<C, C::Err>> { | |
| let mut c = match self.stack.pop() { | |
| Some(c) => c, | |
| None => return None, | |
| }; | |
| match c.backwards(&mut self.receiver) { | |
| Ok(_) => Some(Ok(c)), | |
| Err(e) => { | |
| self.stack.push(c); | |
| Some(Err(e)) | |
| } | |
| } | |
| } | |
| } | |
| use std::any::Any; | |
| use std::error::Error; | |
| trait CommandDyn<T>: Any { | |
| fn forward(&mut self, receiver: &mut T) -> Result<(), Box<Error>>; | |
| fn backwards(&mut self, receiver: &mut T) -> Result<(), Box<Error>>; | |
| } | |
| struct CommandStackDyn<T>{ | |
| stack: Vec<Box<CommandDyn<T>>>, | |
| receiver: T, | |
| } | |
| impl<T> CommandStackDyn<T> { | |
| fn new(receiver: T) -> CommandStackDyn<T> { | |
| CommandStackDyn { | |
| stack: Vec::new(), | |
| receiver: receiver, | |
| } | |
| } | |
| fn push<C: CommandDyn<T>>(&mut self, mut command: C) | |
| -> Result<(), Box<Error>> | |
| { | |
| command.forward(&mut self.receiver)?; | |
| self.stack.push(Box::new(command)); | |
| Ok(()) | |
| } | |
| fn pop(&mut self) -> Option<Result<Box<CommandDyn<T>>, Box<Error>>> { | |
| let mut c = match self.stack.pop() { | |
| Some(c) => c, | |
| None => return None, | |
| }; | |
| match c.backwards(&mut self.receiver) { | |
| Ok(_) => Some(Ok(c)), | |
| Err(e) => { | |
| self.stack.push(c); | |
| Some(Err(e)) | |
| } | |
| } | |
| } | |
| } | |
| fn main() { | |
| } |
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