diff options
Diffstat (limited to 'third_party/rust/darling/src/lib.rs')
| -rw-r--r-- | third_party/rust/darling/src/lib.rs | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/third_party/rust/darling/src/lib.rs b/third_party/rust/darling/src/lib.rs new file mode 100644 index 0000000000..b2be36d0cb --- /dev/null +++ b/third_party/rust/darling/src/lib.rs @@ -0,0 +1,108 @@ +//! # Darling +//! Darling is a tool for declarative attribute parsing in proc macro implementations. +//! +//! +//! ## Design +//! Darling takes considerable design inspiration from [`serde`](https://serde.rs). A data structure that can be +//! read from any attribute implements `FromMeta` (or has an implementation automatically +//! generated using `derive`). Any crate can provide `FromMeta` implementations, even one not +//! specifically geared towards proc-macro authors. +//! +//! Proc-macro crates should provide their own structs which implement or derive `FromDeriveInput`, +//! `FromField`, `FromVariant`, `FromGenerics`, _et alia_ 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 +//! All derivable traits except `FromMeta` support forwarding some fields from the input AST to the derived struct. +//! These fields are matched up by identifier **before** `rename` attribute values are considered, +//! allowing you to use their names for your own properties. +//! The deriving struct is responsible for making sure the types of fields it chooses to declare are compatible with 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`|`T: darling::FromGenerics`|The generics of the passed-in type. This can be `syn::Generics`, `darling::ast::Generics`, or any compatible type.| +//! |`data`|`darling::ast::Data`|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`|`Option<syn::Ident>`|The identifier of the passed-in field, or `None` for tuple fields| +//! |`vis`|`syn::Visibility`|The visibility of the passed-in field| +//! |`ty`|`syn::Type`|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.| +//! +//! ### `FromTypeParam` +//! |Field name|Type|Meaning| +//! |---|---|---| +//! |`ident`|`syn::Ident`|The identifier of the passed-in type param| +//! |`bounds`|`Vec<syn::TypeParamBound>`|The bounds applied to the type param| +//! |`default`|`Option<syn::Type>`|The default type of the parameter, if one exists| +//! |`attrs`|`Vec<syn::Attribute>`|The forwarded attributes from the passed in type param. These are controlled using the `forward_attrs` attribute.| +//! +//! ### `FromVariant` +//! |Field name|Type|Meaning| +//! |---|---|---| +//! |`ident`|`syn::Ident`|The identifier of the passed-in variant| +//! |`discriminant`|`Option<syn::Expr>`|For a variant such as `Example = 2`, the `2`| +//! |`fields`|`darling::ast::Fields<T> where T: FromField`|The fields associated with the variant| +//! |`attrs`|`Vec<syn::Attribute>`|The forwarded attributes from the passed in variant. These are controlled using the `forward_attrs` attribute.| + +extern crate core; + +#[allow(unused_imports)] +#[macro_use] +extern crate darling_macro; + +#[doc(hidden)] +pub use darling_macro::*; + +#[doc(inline)] +pub use darling_core::{ + FromAttributes, FromDeriveInput, FromField, FromGenericParam, FromGenerics, FromMeta, + FromTypeParam, FromVariant, +}; + +#[doc(inline)] +pub use darling_core::{Error, Result}; + +#[doc(inline)] +pub use darling_core::{ast, error, usage, util}; + +// XXX exported so that `ExtractAttribute::extractor` can convert a path into tokens. +// This is likely to change in the future, so only generated code should depend on this export. +#[doc(hidden)] +pub use darling_core::ToTokens; + +/// 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::default::Default; + pub use core::option::Option::{self, None, Some}; + pub use core::result::Result::{self, Err, Ok}; + pub use darling_core::syn; + pub use std::string::ToString; + pub use std::vec::Vec; +} + +#[macro_use] +mod macros_public; |