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// https://doc.rust-lang.org/1.7.0/book/using-rust-without-the-standard-library.html #![no_std] #![doc(html_favicon_url = "https://avatars0.githubusercontent.com/u/32325099?s=460&u=cd848fc83d9739939a4ea2d38108c8bcee199109&v=4")] #![doc(html_logo_url = "https://avatars0.githubusercontent.com/u/32325099?s=460&u=cd848fc83d9739939a4ea2d38108c8bcee199109&v=4")] #![warn(missing_docs)] // #![warn(missing_doc_code_examples)] // Use it if necessary. //! [trybuild]: https://github.com/dtolnay/trybuild //! [macrotest]: https://github.com/eupn/macrotest //! //! Reuse(Struct, Enum) //! ============= //! //! It provides functional macros to reuse fields from [Struct](https://doc.rust-lang.org/std/keyword.struct.html) and [Enum](https://doc.rust-lang.org/std/keyword.enum.html) definition. //! //! ```toml //! [dependencies] //! born = "0.0.1" //! ``` //! //! <br> //! //! ## Examples //! //! Here, macros to build public struct and enum are used. //! //! If you want to build private struct and enum, just use macros that start with private and shouldn't use `pub` inside. //! //! ### Struct //! //! Say you build a demo web server to send private messages. //! //! ``` //! # #[macro_use] extern crate born; //! use born::{ //! nested_macro, //! public_struct, //! }; //! //! public_struct!( //! // pub is required here before struct //! pub struct MessageBase { //! pub text: String //! // pub text: String // , is not required for the struct definition. //! } //! ); //! //! MessageBase!( //! #[derive(Debug, Clone, PartialEq)] //! pub struct Message { //! pub read: bool, //! // read: bool, // pub is optional. //! } //! ); //! //! impl Message { //! fn update_text(&mut self, new_message: String) { //! self.text = new_message //! } //! fn read(&mut self) { //! if self.read == false { //! self.read = true; //! } //! } //! } //! //! MessageBase!( //! #[derive(Debug, Clone, PartialEq)] //! pub struct MessageCreateRequest //! ); //! //! MessageBase!( //! // #[derive(Debug, Clone, PartialEq)] //! pub struct MessageUpdateRequest //! ); //! //! fn main() { //! let message_create_request = MessageCreateRequest { //! text: "I am Steadylearner and 'born' is the crate name.".into(), //! }; //! //! let mut message = Message { //! text: message_create_request.text, //! read: false, //! }; //! println!("{:#?}", &message); //! //! assert_eq!(message, message.clone()); //! //! let message_update_request = MessageUpdateRequest { //! text: "Reuse fields with macros from 'born'.".into(), //! }; //! //! message.update_text(message_update_request.text); //! println!("{:#?}", &message); //! //! message.read(); //! println!("{:#?}", &message); //! } //! ``` //! //! ### Enum //! //! [Compare it with the code example from the Rust documenation.](https://doc.rust-lang.org/stable/rust-by-example/custom_types/enum.html) //! //! ``` //! # #[macro_use] extern crate born; //! use born::{ //! nested_macro, //! private_enum, //! }; //! //! private_enum!( //! enum WebEventBase { //! PageLoad, //! PageUnload, // , here is required if you want to extend it. //! } //! ); //! //! WebEventBase!( //! // #[derive(Debug, Clone, PartialEq)] //! enum WebEvent { //! KeyPress(char), //! Click { x: i64, y: i64 }, //! Paste(String), //! } //! ); //! //! fn inspect(event: WebEvent) { //! match event { //! WebEvent::PageLoad => println!("page loaded"), //! WebEvent::PageUnload => println!("page unloaded"), //! WebEvent::KeyPress(c) => println!("pressed '{}'.", c), //! WebEvent::Paste(s) => println!("pasted \"{}\".", s), //! WebEvent::Click { x, y } => { //! println!("clicked at x={}, y={}.", x, y); //! }, //! } //! } //! //! fn main() { //! let pressed = WebEvent::KeyPress('x'); //! let pasted = WebEvent::Paste("my text".to_owned()); //! let click = WebEvent::Click { x: 20, y: 80 }; //! let load = WebEvent::PageLoad; //! let unload = WebEvent::PageUnload; //! //! inspect(pressed); //! inspect(pasted); //! inspect(click); //! inspect(load); //! inspect(unload); //! } //! ``` //! //! ### Rename //! //! You can rename struct and enum and reuse the exact same fields. //! //! ``` //! # #[macro_use] extern crate born; //! use born::{ //! nested_macro, //! public_struct, //! }; //! //! public_struct!( //! pub struct UserBase { //! pub first_name: String, //! pub last_name: String, //! pub email: String, //! pub password: String, //! } //! ); //! //! UserBase!( //! pub struct User { //! pub id: i64, //! } //! ); //! //! UserBase!( //! pub struct NewUser //! ); //! //! // It is equal to write these manually. //! //! // pub struct User { //! // pub id: i64, //! // pub first_name: String, //! // pub last_name: String, //! // pub email: String, //! // pub password: String, //! // } //! //! // pub struct NewUser { //! // pub first_name: String, //! // pub last_name: String, //! // pub email: String, //! // pub password: String, //! // } //! ``` //! //! <br> //! //! ## Details //! //! - Each struct and enum created from the macros are completely unrelevant to each other except they are built(born) from the same definition //! //! - When you use `private_struct!` and `private_enum!`, you can't use pub keyword in it and others use them. [It wouldn't be logical if a private struct or private enum can have public fields.](https://doc.rust-lang.org/book/ch07-03-paths-for-referring-to-an-item-in-the-module-tree.html#making-structs-and-enums-public) //! //! - `nested_macro!` is required to use the other macros from this crate. It is used to make a macro that creates other macros. //! ```rust //! macro_rules! nested_macro { //! ($($body:tt)*) => { //! macro_rules! __nested_macro { $($body)+ } //! __nested_macro!($); //! } //! } //! ``` //! //! <br> //! //! ## Why not attribute macro? //! //! - [You can reuse the fields with attribute macro also.](https://github.com/steadylearner/born-attribute) But, you need some dependencies. //! //! - [If you want more, please read the official documenation about procedural macros.](https://doc.rust-lang.org/reference/procedural-macros.html#attribute-macros) mod r#enum; mod r#struct; /// You can make a macro that creates other macros with it. /// /// ## Example /// /// ``` /// macro_rules! public_struct { /// (pub struct $commonstruct:ident { $( $commonfieldpub:vis $commonfield:ident: $commonty:ty ),+ $(,)* }) => { /// nested_macro! { /// ($s:tt) => { /// macro_rules! $commonstruct { /// () => { /// pub struct $commonstruct { /// $( $commonfieldpub $commonfield: $commonty, )+ /// } /// }; /// } /// } /// } /// }; /// } /// ``` #[macro_export] macro_rules! nested_macro { ($($body:tt)*) => { macro_rules! __nested_macro { $($body)+ } __nested_macro!($); } } // It will only work with $cargo test --doc or $cargo test #[cfg(doctest)] doc_comment::doctest!("../README.md");