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#![deny(missing_docs)] //! This crate contains a `builder!` macro to declare a struct and a corresponding builder. //! //! The macro is inspired from [jadpole/builder-macro][1], and is designed to remove duplication of field declaration, //! as well as generating appropriate setter methods. //! //! Specify the dependency in your crate's `Cargo.toml`: //! //! ```toml //! [dependencies] //! builder_macro = "0.1.1" # check https://crates.io/crates/builder_macro for the latest version //! ``` //! //! Include the macro inside your crate's `lib.rs` or `main.rs`. //! //! ```rust //! #[macro_use] //! extern crate builder_macro; //! # //! # fn main() {} // necessary to allow doc test to pass //! ``` //! //! # Examples //! //! ## Non-consuming Builder //! //! The simplest usage of the builder macro to generate a [non-consuming builder][2] is: //! //! ```rust,ignore //! builder!(BuilderName -> StructName { //! fieldname: Type = Some(default_value), // or None if there is no sensible default //! }); //! ``` //! //! The above will generate a module private struct and a non-consuming builder with a single private field. //! //! For example, given the following declaration: //! //! ```rust //! # #[macro_use] //! # extern crate builder_macro; //! # //! # fn main() { //! builder!(BuilderName -> StructName { //! value: i32 = Some(1), //! }); //! # } //! ``` //! //! The generated code will function as follows: //! //! ```rust //! # #[macro_use] //! # extern crate builder_macro; //! # //! # fn main() { //! struct StructName { //! value: i32, //! } //! //! /// Auto-generated builder //! struct BuilderName { //! value: Option<i32>, //! } //! //! impl BuilderName { //! /// Construct the builder //! pub fn new() -> BuilderName { BuilderName { value: Some(1), } } //! //! /// Build the struct //! pub fn build(&self) -> StructName { //! let value = self.value.clone().unwrap(); //! StructName{value: value,} //! } //! //! #[allow(dead_code)] //! /// Auto-generated setter //! pub fn value(&mut self, value: i32) -> &mut Self { //! self.value = Some(value); //! self //! } //! } //! # } //! ``` //! //! To generate public structs and builders, see [visbility](#visibility). //! //! ## Consuming Builder //! //! To generate a [consuming builder][3], instead of using `->`, use `=>` between the builder name and the target struct //! name. //! //! ```rust //! # #[macro_use] //! # extern crate builder_macro; //! # //! # fn main() { //! trait Magic { //! fn abracadabra(&mut self) -> i32; //! } //! struct Dust { //! value: i32, //! } //! impl Magic for Dust { //! fn abracadabra(&mut self) -> i32 { //! self.value //! } //! } //! //! // Note: we use => instead of -> for the consuming variant of the builder //! builder!(MyStructBuilder => MyStruct { //! field_trait: Box<Magic> = Some(Box::new(Dust { value: 1 })), //! field_vec: Vec<Box<Magic>> = Some(vec![Box::new(Dust { value: 2 })]), //! }); //! //! let mut my_struct = MyStructBuilder::new().build(); //! //! assert_eq!(my_struct.field_trait.abracadabra(), 1); //! assert_eq!(my_struct.field_vec[0].abracadabra(), 2); //! # } //! ``` //! //! ## Visibility //! //! Generate a builder and struct with module private visibility: //! //! ```rust //! # #[macro_use] //! # extern crate builder_macro; //! # //! # fn main() { //! builder!(MyStructBuilder -> MyStruct { //! field_i32: i32 = Some(123), //! field_str: &'static str = Some("abc"), //! }); //! //! let my_struct = MyStructBuilder::new() //! .field_i32(456) //! .build(); //! assert_eq!(my_struct.field_i32, 456); //! assert_eq!(my_struct.field_str, "abc"); // uses default //! # } //! ``` //! //! Generate a builder and struct with public visibility: //! //! ```rust //! # #[macro_use] //! # extern crate builder_macro; //! # //! # fn main() { //! mod inner { //! builder!(pub MyStructBuilder -> MyStruct { //! pub field_i32: i32 = Some(123), //! field_str: &'static str = Some("abc"), //! }); //! } //! //! let my_struct = inner::MyStructBuilder::new() //! .field_i32(456) //! .build(); //! assert_eq!(my_struct.field_i32, 456); //! //! // The next line will fail compilation if uncommented as field_str is private //! // assert_eq!(my_struct.field_str, "abc"); //! # } //! ``` //! //! ## Full Usage Format //! //! The full macro usage format is: //! //! ```rust //! # #[macro_use] //! # extern crate builder_macro; //! # //! # fn main() { //! // We declare the builder insider a module simply to demonstrate scope //! mod inner { //! builder! { //! /// StructName is an example struct. //! /// These docs are copied over to the generated struct. //! pub BuilderName -> StructName { //! /// a_field is an i32 which must be between 0 and 100 inclusive //! // the trailing comma is mandatory due to how the macro is parsed //! pub a_field: i32 = Some(50), //! //! // None means no default value, a value must be specified when building //! // meta attributes are copied over to the struct's fields //! #[allow(dead_code)] //! a_private_field: &'static str = None, //! }, assertions: { //! assert!(a_field >= 0); //! assert!(a_field <= 100); //! // Yes you can assert on private fields //! assert!(!a_private_field.is_empty()); //! } //! } //! } //! //! let my_struct = inner::BuilderName::new() //! .a_private_field("I must set this to a non-empty string") //! .build(); //! //! assert_eq!(50, my_struct.a_field); //! # } //! ``` //! //! The above will be similar to writing the following: //! //! ```rust //! # #[macro_use] //! # extern crate builder_macro; //! # //! # fn main() { //! mod inner { //! /// StructName is an example struct. //! /// These docs are copied over to the generated struct. //! pub struct StructName { //! /// a_field is an i32 which must be between 0 and 100 inclusive //! pub a_field: i32, //! #[allow(dead_code)] //! a_private_field: &'static str, //! } //! //! /// Auto-generated builder //! pub struct BuilderName { //! /// a_field is an i32 which must be between 0 and 100 inclusive //! a_field: Option<i32>, //! #[allow(dead_code)] //! a_private_field: Option<&'static str>, //! } //! //! impl BuilderName { //! /// Construct the builder //! pub fn new() -> BuilderName { //! BuilderName{a_field: Some(50), a_private_field: None,} //! } //! //! /// Build the struct //! pub fn build(&self) -> StructName { //! let a_field = self.a_field.clone().unwrap(); //! let a_private_field = self.a_private_field.clone().unwrap(); //! //! assert!(a_field >= 0); //! assert!(a_field <= 100); //! assert!(!a_private_field.is_empty()); //! //! StructName { //! a_field: a_field, //! a_private_field: a_private_field, //! } //! } //! //! #[allow(dead_code)] //! /// Auto-generated setter //! pub fn a_field(&mut self, value: i32) -> &mut Self { //! self.a_field = Some(value); //! self //! } //! //! #[allow(dead_code)] //! /// Auto-generated setter //! pub fn a_private_field(&mut self, value: &'static str) //! -> &mut Self { //! self.a_private_field = Some(value); //! self //! } //! } //! } //! //! let my_struct = inner::BuilderName::new() //! .a_private_field("I must set this to a non-empty string") //! .build(); //! //! assert_eq!(50, my_struct.a_field); //! # } //! ``` //! //! [1]: http://jadpole.github.io/rust/builder-macro //! [2]: https://doc.rust-lang.org/style/ownership/builders.html#non-consuming-builders-preferred //! [3]: https://doc.rust-lang.org/style/ownership/builders.html#consuming-builders //! #[macro_use] mod declare_struct_and_builder; #[macro_use] mod parse_struct; #[macro_export] /// Macro to declare a struct and a corresponding builder. See [the module documentation](index.html) for more. macro_rules! builder { ( $( $SPEC:tt )* ) => { parse_struct! { meta: [], spec: $( $SPEC )* } }; } #[cfg(test)] mod test { #[test] fn generates_struct_and_builder_with_defaults() { builder!(MyStructBuilder -> MyStruct { field_i32: i32 = Some(123), field_str: &'static str = Some("abc"), }); let my_struct = MyStructBuilder::new().build(); assert_eq!(my_struct.field_i32, 123); assert_eq!(my_struct.field_str, "abc"); } #[test] fn generates_struct_and_builder_with_parameters() { builder!(MyStructBuilder -> MyStruct { field_i32: i32 = Some(123), field_str: &'static str = Some("abc"), }); let my_struct = MyStructBuilder::new() .field_i32(456) .field_str("str") .build(); assert_eq!(my_struct.field_i32, 456); assert_eq!(my_struct.field_str, "str"); } #[test] fn generates_struct_and_builder_with_generic_types() { builder!(MyStructBuilder -> MyStruct { field_vec: Vec<i32> = Some(vec![123]), }); let my_struct = MyStructBuilder::new().build(); let my_struct_2 = MyStructBuilder::new().field_vec(vec![234, 456]).build(); assert_eq!(my_struct.field_vec, vec![123]); assert_eq!(my_struct_2.field_vec, vec![234, 456]); } #[test] fn generates_struct_and_builder_with_traits_using_default_values() { trait Magic { fn abracadabra(&mut self) -> i32; } struct Dust { value: i32, }; impl Magic for Dust { fn abracadabra(&mut self) -> i32 { self.value } } // Note: we use => instead of -> for the consuming variant of the builder builder!(MyStructBuilder => MyStruct { field_trait: Box<Magic> = Some(Box::new(Dust { value: 1 })), field_vec: Vec<Box<Magic>> = Some(vec![Box::new(Dust { value: 2 })]), }); let mut my_struct = MyStructBuilder::new().build(); assert_eq!(my_struct.field_trait.abracadabra(), 1); assert_eq!(my_struct.field_vec[0].abracadabra(), 2); } #[test] fn generates_struct_and_builder_with_traits_specifying_parameters() { trait Magic { fn abracadabra(&mut self) -> i32; } struct Dust { value: i32, }; impl Magic for Dust { fn abracadabra(&mut self) -> i32 { self.value } } // Note: we use => instead of -> for the consuming variant of the builder builder!(MyStructBuilder => MyStruct { field_trait: Box<Magic> = None, field_vec: Vec<Box<Magic>> = None, }); let mut my_struct = MyStructBuilder::new() .field_trait(Box::new(Dust { value: 1 })) .field_vec(vec![Box::new(Dust { value: 2 })]) .build(); assert_eq!(my_struct.field_trait.abracadabra(), 1); assert_eq!(my_struct.field_vec[0].abracadabra(), 2); } #[test] #[should_panic(expected = "assertion failed")] fn generated_build_method_uses_assertions() { builder!(MyStructBuilder -> MyStruct { field_i32: i32 = Some(123), }, assertions: { assert!(field_i32 > 0); }); let my_struct = MyStructBuilder::new() .field_i32(-1) .build(); assert_eq!(my_struct.field_i32, -1); } mod visibility_test { builder!(OuterStructBuilder -> OuterStruct { field_i32: i32 = Some(1), }); mod inner { builder!(MyStructBuilder -> MyStruct { field_i32: i32 = Some(1), }); builder!(pub InnerStructBuilder -> InnerStruct { pub field_i32: i32 = Some(1), }); #[test] fn can_access_private_struct_from_within_module() { let my_struct = MyStructBuilder::new().build(); assert_eq!(my_struct.field_i32, 1); } #[test] fn can_access_private_outer_struct_from_inner_module() { let outer_struct = super::OuterStructBuilder::new().build(); assert_eq!(outer_struct.field_i32, 1); } } #[test] fn can_access_public_struct_from_outside_module() { let inner_struct = inner::InnerStructBuilder::new().build(); assert_eq!(inner_struct.field_i32, 1); } // The following causes a compilation failure if uncommented // #[test] // fn cannot_access_private_struct() { // let my_struct = inner::MyStructBuilder::new().build(); // assert_eq!(my_struct.field_i32, 0); // } } }