1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80
//! # Darling //! Darling is a tool for declarative attribute parsing in proc macro implementations. //! //! //! ## Design //! Darling takes considerable design inspiration from [`serde`]. A data structure that can be //! read from any attribute implements `FromMetaItem` (or has an implementation automatically //! generated using `derive`). Any crate can provide `FromMetaItem` implementations, even one not //! specifically geared towards proc-macro authors. //! //! Proc-macro crates should provide their own structs which implement or derive `FromDeriveInput` and //! `FromField` to gather settings relevant to their operation. //! //! ## Attributes //! There are a number of attributes that `darling` exposes to enable finer-grained control over the code //! it generates. //! //! * **Field renaming**: You can use `#[darling(rename="new_name")]` on a field to change the name Darling looks for. //! You can also use `#[darling(rename_all="...")]` at the struct or enum level to apply a casing rule to all fields or variants. //! * **Map function**: You can use `#[darling(map="path::to::function")]` to run code on a field before its stored in the struct. //! * **Default values**: You can use `#[darling(default)]` at the type or field level to use that type's default value to fill //! in values not specified by the caller. //! * **Skipped fields**: You can skip a variant or field using `#[darling(skip)]`. Fields marked with this will fall back to //! `Default::default()` for their value, but you can override that with an explicit default or a value from the type-level default. //! //! ## Forwarded Fields //! The traits `FromDeriveInput` and `FromField` support forwarding fields from the input AST directly //! to the derived struct. These fields are matched up by identifier **before** `rename` attribute values are //! considered. The deriving struct is responsible for making sure the types of fields it does declare match this //! table. //! //! A deriving struct is free to include or exclude any of the fields below. //! //! ### `FromDeriveInput` //! |Field name|Type|Meaning| //! |---|---|---| //! |`ident`|`syn::Ident`|The identifier of the passed-in type| //! |`vis`|`syn::Visibility`|The visibility of the passed-in type| //! |`generics`|`syn::Generics`|The generics of the passed-in type| //! |`body`|`darling::ast::Body`|The body of the passed-in type| //! |`attrs`|`Vec<syn::Attribute>`|The forwarded attributes from the passed in type. These are controlled using the `forward_attrs` attribute.| //! //! ### `FromField` //! |Field name|Type|Meaning| //! |---|---|---| //! |`ident`|`syn::Ident`|The identifier of the passed-in field| //! |`vis`|`syn::Visibility`|The visibility of the passed-in field| //! |`ty`|`syn::Ty`|The type of the passed-in field| //! |`attrs`|`Vec<syn::Attribute>`|The forwarded attributes from the passed in field. These are controlled using the `forward_attrs` attribute.| extern crate core; extern crate darling_core; #[allow(unused_imports)] #[macro_use] extern crate darling_macro; #[doc(hidden)] pub use darling_macro::*; #[doc(inline)] pub use darling_core::{FromMetaItem, FromDeriveInput, FromField, FromVariant}; #[doc(inline)] pub use darling_core::{Result, Error}; #[doc(inline)] pub use darling_core::{ast, error, util}; /// Core/std trait re-exports. This should help produce generated code which doesn't /// depend on `std` unnecessarily, and avoids problems caused by aliasing `std` or any /// of the referenced types. #[doc(hidden)] pub mod export { pub use ::core::convert::From; pub use ::core::option::Option::{self, Some, None}; pub use ::core::result::Result::{self, Ok, Err}; pub use ::core::default::Default; pub use ::std::vec::Vec; }