diff options
Diffstat (limited to 'src/doc/book/listings/ch17-oop/listing-17-18')
4 files changed, 120 insertions, 0 deletions
diff --git a/src/doc/book/listings/ch17-oop/listing-17-18/Cargo.lock b/src/doc/book/listings/ch17-oop/listing-17-18/Cargo.lock new file mode 100644 index 000000000..b6f4232c6 --- /dev/null +++ b/src/doc/book/listings/ch17-oop/listing-17-18/Cargo.lock @@ -0,0 +1,6 @@ +# This file is automatically @generated by Cargo. +# It is not intended for manual editing. +[[package]] +name = "blog" +version = "0.1.0" + diff --git a/src/doc/book/listings/ch17-oop/listing-17-18/Cargo.toml b/src/doc/book/listings/ch17-oop/listing-17-18/Cargo.toml new file mode 100644 index 000000000..1619af5c6 --- /dev/null +++ b/src/doc/book/listings/ch17-oop/listing-17-18/Cargo.toml @@ -0,0 +1,6 @@ +[package] +name = "blog" +version = "0.1.0" +edition = "2021" + +[dependencies] diff --git a/src/doc/book/listings/ch17-oop/listing-17-18/src/lib.rs b/src/doc/book/listings/ch17-oop/listing-17-18/src/lib.rs new file mode 100644 index 000000000..1bac8a87a --- /dev/null +++ b/src/doc/book/listings/ch17-oop/listing-17-18/src/lib.rs @@ -0,0 +1,94 @@ +pub struct Post { + state: Option<Box<dyn State>>, + content: String, +} + +impl Post { + pub fn new() -> Post { + Post { + state: Some(Box::new(Draft {})), + content: String::new(), + } + } + + pub fn add_text(&mut self, text: &str) { + self.content.push_str(text); + } + + pub fn content(&self) -> &str { + self.state.as_ref().unwrap().content(self) + } + + pub fn request_review(&mut self) { + if let Some(s) = self.state.take() { + self.state = Some(s.request_review()) + } + } + + pub fn approve(&mut self) { + if let Some(s) = self.state.take() { + self.state = Some(s.approve()) + } + } +} + +// ANCHOR: here +trait State { + // --snip-- + // ANCHOR_END: here + fn request_review(self: Box<Self>) -> Box<dyn State>; + fn approve(self: Box<Self>) -> Box<dyn State>; + + // ANCHOR: here + fn content<'a>(&self, post: &'a Post) -> &'a str { + "" + } +} + +// --snip-- +// ANCHOR_END: here + +struct Draft {} + +impl State for Draft { + fn request_review(self: Box<Self>) -> Box<dyn State> { + Box::new(PendingReview {}) + } + + fn approve(self: Box<Self>) -> Box<dyn State> { + self + } +} + +struct PendingReview {} + +impl State for PendingReview { + fn request_review(self: Box<Self>) -> Box<dyn State> { + self + } + + fn approve(self: Box<Self>) -> Box<dyn State> { + Box::new(Published {}) + } +} + +// ANCHOR: here +struct Published {} + +impl State for Published { + // --snip-- + // ANCHOR_END: here + fn request_review(self: Box<Self>) -> Box<dyn State> { + self + } + + fn approve(self: Box<Self>) -> Box<dyn State> { + self + } + + // ANCHOR: here + fn content<'a>(&self, post: &'a Post) -> &'a str { + &post.content + } +} +// ANCHOR_END: here diff --git a/src/doc/book/listings/ch17-oop/listing-17-18/src/main.rs b/src/doc/book/listings/ch17-oop/listing-17-18/src/main.rs new file mode 100644 index 000000000..14b4c0824 --- /dev/null +++ b/src/doc/book/listings/ch17-oop/listing-17-18/src/main.rs @@ -0,0 +1,14 @@ +use blog::Post; + +fn main() { + let mut post = Post::new(); + + post.add_text("I ate a salad for lunch today"); + assert_eq!("", post.content()); + + post.request_review(); + assert_eq!("", post.content()); + + post.approve(); + assert_eq!("I ate a salad for lunch today", post.content()); +} |