82 lines
1.6 KiB
Rust
82 lines
1.6 KiB
Rust
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pub struct Post {
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state: Option<Box<dyn State>>,
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content: String,
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}
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impl Post {
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pub fn new() -> Post {
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Post {
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state: Some(Box::new(Draft {})),
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content: String::new(),
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}
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}
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pub fn add_text(&mut self, text: &str) {
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self.content.push_str(text);
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}
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pub fn content(&self) -> &str {
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self.state.as_ref().unwrap().content(&self)
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}
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pub fn request_review(&mut self) {
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if let Some(s) = self.state.take() {
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self.state = Some(s.request_review())
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}
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}
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pub fn approve(&mut self) {
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if let Some(s) = self.state.take() {
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self.state = Some(s.approve())
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}
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}
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}
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trait State {
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fn request_review(self: Box<Self>) -> Box<dyn State>;
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fn approve(self: Box<Self>) -> Box<dyn State>;
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fn content<'a>(&self, post: &'a Post) -> &'a str {
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""
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}
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}
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struct Draft {}
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impl State for Draft {
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fn request_review(self: Box<Self>) -> Box<dyn State> {
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Box::new(PendingReview {})
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}
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fn approve(self: Box<Self>) -> Box<dyn State> {
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self
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}
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}
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struct PendingReview {}
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impl State for PendingReview {
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fn request_review(self: Box<Self>) -> Box<dyn State> {
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self
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}
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fn approve(self: Box<Self>) -> Box<dyn State> {
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Box::new(Published {})
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}
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}
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struct Published {}
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impl State for Published {
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fn request_review(self: Box<Self>) -> Box<dyn State> {
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self
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}
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fn approve(self: Box<Self>) -> Box<dyn State> {
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self
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}
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fn content<'a>(&self, post: &'a Post) -> &'a str {
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&post.content
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}
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}
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