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Diffstat (limited to 'third_party/rust/synstructure')
| -rw-r--r-- | third_party/rust/synstructure/.cargo-checksum.json | 1 | ||||
| -rw-r--r-- | third_party/rust/synstructure/Cargo.toml | 44 | ||||
| -rw-r--r-- | third_party/rust/synstructure/LICENSE | 7 | ||||
| -rw-r--r-- | third_party/rust/synstructure/README.md | 159 | ||||
| -rw-r--r-- | third_party/rust/synstructure/src/lib.rs | 2488 | ||||
| -rw-r--r-- | third_party/rust/synstructure/src/macros.rs | 250 |
6 files changed, 2949 insertions, 0 deletions
diff --git a/third_party/rust/synstructure/.cargo-checksum.json b/third_party/rust/synstructure/.cargo-checksum.json new file mode 100644 index 0000000000..bb02a4ca35 --- /dev/null +++ b/third_party/rust/synstructure/.cargo-checksum.json @@ -0,0 +1 @@ +{"files":{"Cargo.toml":"b9f3ce31a9ac80dc24f4afac7108b7cff44399f8d7503dc4addea4d256431a73","LICENSE":"219920e865eee70b7dcfc948a86b099e7f4fe2de01bcca2ca9a20c0a033f2b59","README.md":"a528e7356db49ea813c3290dd4f6b15d8e6c0a870cfc07a2df0f3d1381c575bf","src/lib.rs":"b8d9885399b22a5ee92b51e4ca757427da07775e940b25e1573180d9e8faf7d0","src/macros.rs":"e7cf1808faf5dac5ca25bd40ad99e95c2aab4f9899bd9327898761ea86271f7c"},"package":"f36bdaa60a83aca3921b5259d5400cbf5e90fc51931376a9bd4a0eb79aa7210f"}
\ No newline at end of file diff --git a/third_party/rust/synstructure/Cargo.toml b/third_party/rust/synstructure/Cargo.toml new file mode 100644 index 0000000000..03398567e6 --- /dev/null +++ b/third_party/rust/synstructure/Cargo.toml @@ -0,0 +1,44 @@ +# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO +# +# When uploading crates to the registry Cargo will automatically +# "normalize" Cargo.toml files for maximal compatibility +# with all versions of Cargo and also rewrite `path` dependencies +# to registry (e.g., crates.io) dependencies. +# +# If you are reading this file be aware that the original Cargo.toml +# will likely look very different (and much more reasonable). +# See Cargo.toml.orig for the original contents. + +[package] +edition = "2018" +name = "synstructure" +version = "0.12.6" +authors = ["Nika Layzell <nika@thelayzells.com>"] +include = ["src/**/*", "Cargo.toml", "README.md", "LICENSE"] +description = "Helper methods and macros for custom derives" +documentation = "https://docs.rs/synstructure" +readme = "README.md" +keywords = ["syn", "macros", "derive", "expand_substructure", "enum"] +license = "MIT" +repository = "https://github.com/mystor/synstructure" +[dependencies.proc-macro2] +version = "1" +default-features = false + +[dependencies.quote] +version = "1" +default-features = false + +[dependencies.syn] +version = "1" +features = ["derive", "parsing", "printing", "clone-impls", "visit", "extra-traits"] +default-features = false + +[dependencies.unicode-xid] +version = "0.2" +[dev-dependencies.synstructure_test_traits] +version = "0.1" + +[features] +default = ["proc-macro"] +proc-macro = ["proc-macro2/proc-macro", "syn/proc-macro", "quote/proc-macro"] diff --git a/third_party/rust/synstructure/LICENSE b/third_party/rust/synstructure/LICENSE new file mode 100644 index 0000000000..f78f1c15d1 --- /dev/null +++ b/third_party/rust/synstructure/LICENSE @@ -0,0 +1,7 @@ +Copyright 2016 Nika Layzell + +Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. diff --git a/third_party/rust/synstructure/README.md b/third_party/rust/synstructure/README.md new file mode 100644 index 0000000000..b72b7bd9d5 --- /dev/null +++ b/third_party/rust/synstructure/README.md @@ -0,0 +1,159 @@ +# synstructure + +[](https://crates.io/crates/synstructure) +[](https://docs.rs/synstructure) +[](https://travis-ci.org/mystor/synstructure) +[](https://blog.rust-lang.org/2018/12/06/Rust-1.31-and-rust-2018.html) + +> NOTE: What follows is an exerpt from the module level documentation. For full +> details read the docs on [docs.rs](https://docs.rs/synstructure/) + +This crate provides helper types for matching against enum variants, and +extracting bindings to each of the fields in the deriving Struct or Enum in +a generic way. + +If you are writing a `#[derive]` which needs to perform some operation on +every field, then you have come to the right place! + +# Example: `WalkFields` +### Trait Implementation +```rust +pub trait WalkFields: std::any::Any { + fn walk_fields(&self, walk: &mut FnMut(&WalkFields)); +} +impl WalkFields for i32 { + fn walk_fields(&self, _walk: &mut FnMut(&WalkFields)) {} +} +``` + +### Custom Derive +```rust +#[macro_use] +extern crate synstructure; +#[macro_use] +extern crate quote; +extern crate proc_macro2; + +fn walkfields_derive(s: synstructure::Structure) -> proc_macro2::TokenStream { + let body = s.each(|bi| quote!{ + walk(#bi) + }); + + s.bound_impl(quote!(example_traits::WalkFields), quote!{ + fn walk_fields(&self, walk: &mut FnMut(&example_traits::WalkFields)) { + match *self { #body } + } + }) +} +decl_derive!([WalkFields] => walkfields_derive); + +/* + * Test Case + */ +fn main() { + test_derive! { + walkfields_derive { + enum A<T> { + B(i32, T), + C(i32), + } + } + expands to { + #[allow(non_upper_case_globals)] + const _DERIVE_example_traits_WalkFields_FOR_A: () = { + extern crate example_traits; + impl<T> example_traits::WalkFields for A<T> + where T: example_traits::WalkFields + { + fn walk_fields(&self, walk: &mut FnMut(&example_traits::WalkFields)) { + match *self { + A::B(ref __binding_0, ref __binding_1,) => { + { walk(__binding_0) } + { walk(__binding_1) } + } + A::C(ref __binding_0,) => { + { walk(__binding_0) } + } + } + } + } + }; + } + } +} +``` + +# Example: `Interest` +### Trait Implementation +```rust +pub trait Interest { + fn interesting(&self) -> bool; +} +impl Interest for i32 { + fn interesting(&self) -> bool { *self > 0 } +} +``` + +### Custom Derive +```rust +#[macro_use] +extern crate synstructure; +#[macro_use] +extern crate quote; +extern crate proc_macro2; + +fn interest_derive(mut s: synstructure::Structure) -> proc_macro2::TokenStream { + let body = s.fold(false, |acc, bi| quote!{ + #acc || example_traits::Interest::interesting(#bi) + }); + + s.bound_impl(quote!(example_traits::Interest), quote!{ + fn interesting(&self) -> bool { + match *self { + #body + } + } + }) +} +decl_derive!([Interest] => interest_derive); + +/* + * Test Case + */ +fn main() { + test_derive!{ + interest_derive { + enum A<T> { + B(i32, T), + C(i32), + } + } + expands to { + #[allow(non_upper_case_globals)] + const _DERIVE_example_traits_Interest_FOR_A: () = { + extern crate example_traits; + impl<T> example_traits::Interest for A<T> + where T: example_traits::Interest + { + fn interesting(&self) -> bool { + match *self { + A::B(ref __binding_0, ref __binding_1,) => { + false || + example_traits::Interest::interesting(__binding_0) || + example_traits::Interest::interesting(__binding_1) + } + A::C(ref __binding_0,) => { + false || + example_traits::Interest::interesting(__binding_0) + } + } + } + } + }; + } + } +} +``` + +For more example usage, consider investigating the `abomonation_derive` crate, +which makes use of this crate, and is fairly simple. diff --git a/third_party/rust/synstructure/src/lib.rs b/third_party/rust/synstructure/src/lib.rs new file mode 100644 index 0000000000..2cd2b88011 --- /dev/null +++ b/third_party/rust/synstructure/src/lib.rs @@ -0,0 +1,2488 @@ +//! This crate provides helper types for matching against enum variants, and +//! extracting bindings to each of the fields in the deriving Struct or Enum in +//! a generic way. +//! +//! If you are writing a `#[derive]` which needs to perform some operation on +//! every field, then you have come to the right place! +//! +//! # Example: `WalkFields` +//! ### Trait Implementation +//! ``` +//! pub trait WalkFields: std::any::Any { +//! fn walk_fields(&self, walk: &mut FnMut(&WalkFields)); +//! } +//! impl WalkFields for i32 { +//! fn walk_fields(&self, _walk: &mut FnMut(&WalkFields)) {} +//! } +//! ``` +//! +//! ### Custom Derive +//! ``` +//! # use quote::quote; +//! fn walkfields_derive(s: synstructure::Structure) -> proc_macro2::TokenStream { +//! let body = s.each(|bi| quote!{ +//! walk(#bi) +//! }); +//! +//! s.gen_impl(quote! { +//! extern crate synstructure_test_traits; +//! +//! gen impl synstructure_test_traits::WalkFields for @Self { +//! fn walk_fields(&self, walk: &mut FnMut(&synstructure_test_traits::WalkFields)) { +//! match *self { #body } +//! } +//! } +//! }) +//! } +//! # const _IGNORE: &'static str = stringify!( +//! synstructure::decl_derive!([WalkFields] => walkfields_derive); +//! # ); +//! +//! /* +//! * Test Case +//! */ +//! fn main() { +//! synstructure::test_derive! { +//! walkfields_derive { +//! enum A<T> { +//! B(i32, T), +//! C(i32), +//! } +//! } +//! expands to { +//! #[allow(non_upper_case_globals)] +//! const _DERIVE_synstructure_test_traits_WalkFields_FOR_A: () = { +//! extern crate synstructure_test_traits; +//! impl<T> synstructure_test_traits::WalkFields for A<T> +//! where T: synstructure_test_traits::WalkFields +//! { +//! fn walk_fields(&self, walk: &mut FnMut(&synstructure_test_traits::WalkFields)) { +//! match *self { +//! A::B(ref __binding_0, ref __binding_1,) => { +//! { walk(__binding_0) } +//! { walk(__binding_1) } +//! } +//! A::C(ref __binding_0,) => { +//! { walk(__binding_0) } +//! } +//! } +//! } +//! } +//! }; +//! } +//! } +//! } +//! ``` +//! +//! # Example: `Interest` +//! ### Trait Implementation +//! ``` +//! pub trait Interest { +//! fn interesting(&self) -> bool; +//! } +//! impl Interest for i32 { +//! fn interesting(&self) -> bool { *self > 0 } +//! } +//! ``` +//! +//! ### Custom Derive +//! ``` +//! # use quote::quote; +//! fn interest_derive(mut s: synstructure::Structure) -> proc_macro2::TokenStream { +//! let body = s.fold(false, |acc, bi| quote!{ +//! #acc || synstructure_test_traits::Interest::interesting(#bi) +//! }); +//! +//! s.gen_impl(quote! { +//! extern crate synstructure_test_traits; +//! gen impl synstructure_test_traits::Interest for @Self { +//! fn interesting(&self) -> bool { +//! match *self { +//! #body +//! } +//! } +//! } +//! }) +//! } +//! # const _IGNORE: &'static str = stringify!( +//! synstructure::decl_derive!([Interest] => interest_derive); +//! # ); +//! +//! /* +//! * Test Case +//! */ +//! fn main() { +//! synstructure::test_derive!{ +//! interest_derive { +//! enum A<T> { +//! B(i32, T), +//! C(i32), +//! } +//! } +//! expands to { +//! #[allow(non_upper_case_globals)] +//! const _DERIVE_synstructure_test_traits_Interest_FOR_A: () = { +//! extern crate synstructure_test_traits; +//! impl<T> synstructure_test_traits::Interest for A<T> +//! where T: synstructure_test_traits::Interest +//! { +//! fn interesting(&self) -> bool { +//! match *self { +//! A::B(ref __binding_0, ref __binding_1,) => { +//! false || +//! synstructure_test_traits::Interest::interesting(__binding_0) || +//! synstructure_test_traits::Interest::interesting(__binding_1) +//! } +//! A::C(ref __binding_0,) => { +//! false || +//! synstructure_test_traits::Interest::interesting(__binding_0) +//! } +//! } +//! } +//! } +//! }; +//! } +//! } +//! } +//! ``` +//! +//! For more example usage, consider investigating the `abomonation_derive` crate, +//! which makes use of this crate, and is fairly simple. + +#[cfg(all( + not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "wasi"))), + feature = "proc-macro" +))] +extern crate proc_macro; + +use std::collections::HashSet; + +use syn::parse::{ParseStream, Parser}; +use syn::visit::{self, Visit}; +use syn::{ + braced, punctuated, token, Attribute, Data, DeriveInput, Error, Expr, Field, Fields, + FieldsNamed, FieldsUnnamed, GenericParam, Generics, Ident, PredicateType, Result, Token, + TraitBound, Type, TypeMacro, TypeParamBound, TypePath, WhereClause, WherePredicate, +}; + +use quote::{format_ident, quote_spanned, ToTokens}; +// re-export the quote! macro so we can depend on it being around in our macro's +// implementations. +#[doc(hidden)] +pub use quote::quote; + +use unicode_xid::UnicodeXID; + +use proc_macro2::{Span, TokenStream, TokenTree}; + +// NOTE: This module has documentation hidden, as it only exports macros (which +// always appear in the root of the crate) and helper methods / re-exports used +// in the implementation of those macros. +#[doc(hidden)] +pub mod macros; + +/// Changes how bounds are added +#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)] +pub enum AddBounds { + /// Add for fields and generics + Both, + /// Fields only + Fields, + /// Generics only + Generics, + /// None + None, + #[doc(hidden)] + __Nonexhaustive, +} + +/// The type of binding to use when generating a pattern. +#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)] +pub enum BindStyle { + /// `x` + Move, + /// `mut x` + MoveMut, + /// `ref x` + Ref, + /// `ref mut x` + RefMut, +} + +impl ToTokens for BindStyle { + fn to_tokens(&self, tokens: &mut TokenStream) { + match self { + BindStyle::Move => {} + BindStyle::MoveMut => quote_spanned!(Span::call_site() => mut).to_tokens(tokens), + BindStyle::Ref => quote_spanned!(Span::call_site() => ref).to_tokens(tokens), + BindStyle::RefMut => quote_spanned!(Span::call_site() => ref mut).to_tokens(tokens), + } + } +} + +// Internal method for merging seen_generics arrays together. +fn generics_fuse(res: &mut Vec<bool>, new: &[bool]) { + for (i, &flag) in new.iter().enumerate() { + if i == res.len() { + res.push(false); + } + if flag { + res[i] = true; + } + } +} + +// Internal method for extracting the set of generics which have been matched. +fn fetch_generics<'a>(set: &[bool], generics: &'a Generics) -> Vec<&'a Ident> { + let mut tys = vec![]; + for (&seen, param) in set.iter().zip(generics.params.iter()) { + if seen { + if let GenericParam::Type(tparam) = param { + tys.push(&tparam.ident) + } + } + } + tys +} + +// Internal method for sanitizing an identifier for hygiene purposes. +fn sanitize_ident(s: &str) -> Ident { + let mut res = String::with_capacity(s.len()); + for mut c in s.chars() { + if !UnicodeXID::is_xid_continue(c) { + c = '_' + } + // Deduplicate consecutive _ characters. + if res.ends_with('_') && c == '_' { + continue; + } + res.push(c); + } + Ident::new(&res, Span::call_site()) +} + +// Internal method to merge two Generics objects together intelligently. +fn merge_generics(into: &mut Generics, from: &Generics) -> Result<()> { + // Try to add the param into `into`, and merge parmas with identical names. + for p in &from.params { + for op in &into.params { + match (op, p) { + (GenericParam::Type(otp), GenericParam::Type(tp)) => { + // NOTE: This is only OK because syn ignores the span for equality purposes. + if otp.ident == tp.ident { + return Err(Error::new_spanned( + p, + format!( + "Attempted to merge conflicting generic parameters: {} and {}", + quote!(#op), + quote!(#p) + ), + )); + } + } + (GenericParam::Lifetime(olp), GenericParam::Lifetime(lp)) => { + // NOTE: This is only OK because syn ignores the span for equality purposes. + if olp.lifetime == lp.lifetime { + return Err(Error::new_spanned( + p, + format!( + "Attempted to merge conflicting generic parameters: {} and {}", + quote!(#op), + quote!(#p) + ), + )); + } + } + // We don't support merging Const parameters, because that wouldn't make much sense. + _ => (), + } + } + into.params.push(p.clone()); + } + + // Add any where clauses from the input generics object. + if let Some(from_clause) = &from.where_clause { + into.make_where_clause() + .predicates + .extend(from_clause.predicates.iter().cloned()); + } + + Ok(()) +} + +/// Helper method which does the same thing as rustc 1.20's +/// `Option::get_or_insert_with`. This method is used to keep backwards +/// compatibility with rustc 1.15. +fn get_or_insert_with<T, F>(opt: &mut Option<T>, f: F) -> &mut T +where + F: FnOnce() -> T, +{ + if opt.is_none() { + *opt = Some(f()); + } + + match opt { + Some(v) => v, + None => unreachable!(), + } +} + +/// Information about a specific binding. This contains both an `Ident` +/// reference to the given field, and the syn `&'a Field` descriptor for that +/// field. +/// +/// This type supports `quote::ToTokens`, so can be directly used within the +/// `quote!` macro. It expands to a reference to the matched field. +#[derive(Debug, Clone, PartialEq, Eq, Hash)] +pub struct BindingInfo<'a> { + /// The name which this BindingInfo will bind to. + pub binding: Ident, + + /// The type of binding which this BindingInfo will create. + pub style: BindStyle, + + field: &'a Field, + + // These are used to determine which type parameters are avaliable. + generics: &'a Generics, + seen_generics: Vec<bool>, + // The original index of the binding + // this will not change when .filter() is called + index: usize, +} + +impl<'a> ToTokens for BindingInfo<'a> { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.binding.to_tokens(tokens); + } +} + +impl<'a> BindingInfo<'a> { + /// Returns a reference to the underlying `syn` AST node which this + /// `BindingInfo` references + pub fn ast(&self) -> &'a Field { + self.field + } + + /// Generates the pattern fragment for this field binding. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B{ a: i32, b: i32 }, + /// C(u32), + /// } + /// }; + /// let s = Structure::new(&di); + /// + /// assert_eq!( + /// s.variants()[0].bindings()[0].pat().to_string(), + /// quote! { + /// ref __binding_0 + /// }.to_string() + /// ); + /// ``` + pub fn pat(&self) -> TokenStream { + let BindingInfo { binding, style, .. } = self; + quote!(#style #binding) + } + + /// Returns a list of the type parameters which are referenced in this + /// field's type. + /// + /// # Caveat + /// + /// If the field contains any macros in type position, all parameters will + /// be considered bound. This is because we cannot determine which type + /// parameters are bound by type macros. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// struct A<T, U> { + /// a: Option<T>, + /// b: U, + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// assert_eq!( + /// s.variants()[0].bindings()[0].referenced_ty_params(), + /// &["e::format_ident!("T")] + /// ); + /// ``` + pub fn referenced_ty_params(&self) -> Vec<&'a Ident> { + fetch_generics(&self.seen_generics, self.generics) + } +} + +/// This type is similar to `syn`'s `Variant` type, however each of the fields +/// are references rather than owned. When this is used as the AST for a real +/// variant, this struct simply borrows the fields of the `syn::Variant`, +/// however this type may also be used as the sole variant for a struct. +#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)] +pub struct VariantAst<'a> { + pub attrs: &'a [Attribute], + pub ident: &'a Ident, + pub fields: &'a Fields, + pub discriminant: &'a Option<(token::Eq, Expr)>, +} + +/// A wrapper around a `syn::DeriveInput`'s variant which provides utilities +/// for destructuring `Variant`s with `match` expressions. +#[derive(Debug, Clone, PartialEq, Eq, Hash)] +pub struct VariantInfo<'a> { + pub prefix: Option<&'a Ident>, + bindings: Vec<BindingInfo<'a>>, + ast: VariantAst<'a>, + generics: &'a Generics, + // The original length of `bindings` before any `.filter()` calls + original_length: usize, +} + +/// Helper function used by the VariantInfo constructor. Walks all of the types +/// in `field` and returns a list of the type parameters from `ty_params` which +/// are referenced in the field. +fn get_ty_params(field: &Field, generics: &Generics) -> Vec<bool> { + // Helper type. Discovers all identifiers inside of the visited type, + // and calls a callback with them. + struct BoundTypeLocator<'a> { + result: Vec<bool>, + generics: &'a Generics, + } + + impl<'a> Visit<'a> for BoundTypeLocator<'a> { + // XXX: This also (intentionally) captures paths like T::SomeType. Is + // this desirable? + fn visit_ident(&mut self, id: &Ident) { + for (idx, i) in self.generics.params.iter().enumerate() { + if let GenericParam::Type(tparam) = i { + if tparam.ident == *id { + self.result[idx] = true; + } + } + } + } + + fn visit_type_macro(&mut self, x: &'a TypeMacro) { + // If we see a type_mac declaration, then we can't know what type parameters + // it might be binding, so we presume it binds all of them. + for r in &mut self.result { + *r = true; + } + visit::visit_type_macro(self, x) + } + } + + let mut btl = BoundTypeLocator { + result: vec![false; generics.params.len()], + generics, + }; + + btl.visit_type(&field.ty); + + btl.result +} + +impl<'a> VariantInfo<'a> { + fn new(ast: VariantAst<'a>, prefix: Option<&'a Ident>, generics: &'a Generics) -> Self { + let bindings = match ast.fields { + Fields::Unit => vec![], + Fields::Unnamed(FieldsUnnamed { + unnamed: fields, .. + }) + | Fields::Named(FieldsNamed { named: fields, .. }) => { + fields + .into_iter() + .enumerate() + .map(|(i, field)| { + BindingInfo { + // XXX: This has to be call_site to avoid privacy + // when deriving on private fields. + binding: format_ident!("__binding_{}", i), + style: BindStyle::Ref, + field, + generics, + seen_generics: get_ty_params(field, generics), + index: i, + } + }) + .collect::<Vec<_>>() + } + }; + + let original_length = bindings.len(); + VariantInfo { + prefix, + bindings, + ast, + generics, + original_length, + } + } + + /// Returns a slice of the bindings in this Variant. + pub fn bindings(&self) -> &[BindingInfo<'a>] { + &self.bindings + } + + /// Returns a mut slice of the bindings in this Variant. + pub fn bindings_mut(&mut self) -> &mut [BindingInfo<'a>] { + &mut self.bindings + } + + /// Returns a `VariantAst` object which contains references to the + /// underlying `syn` AST node which this `Variant` was created from. + pub fn ast(&self) -> VariantAst<'a> { + self.ast + } + + /// True if any bindings were omitted due to a `filter` call. + pub fn omitted_bindings(&self) -> bool { + self.original_length != self.bindings.len() + } + + /// Generates the match-arm pattern which could be used to match against this Variant. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B(i32, i32), + /// C(u32), + /// } + /// }; + /// let s = Structure::new(&di); + /// + /// assert_eq!( + /// s.variants()[0].pat().to_string(), + /// quote!{ + /// A::B(ref __binding_0, ref __binding_1,) + /// }.to_string() + /// ); + /// ``` + pub fn pat(&self) -> TokenStream { + let mut t = TokenStream::new(); + if let Some(prefix) = self.prefix { + prefix.to_tokens(&mut t); + quote!(::).to_tokens(&mut t); + } + self.ast.ident.to_tokens(&mut t); + match self.ast.fields { + Fields::Unit => { + assert!(self.bindings.is_empty()); + } + Fields::Unnamed(..) => token::Paren(Span::call_site()).surround(&mut t, |t| { + let mut expected_index = 0; + for binding in &self.bindings { + while expected_index < binding.index { + quote!(_,).to_tokens(t); + expected_index += 1; + } + binding.pat().to_tokens(t); + quote!(,).to_tokens(t); + expected_index += 1; + } + if expected_index != self.original_length { + quote!(..).to_tokens(t); + } + }), + Fields::Named(..) => token::Brace(Span::call_site()).surround(&mut t, |t| { + for binding in &self.bindings { + binding.field.ident.to_tokens(t); + quote!(:).to_tokens(t); + binding.pat().to_tokens(t); + quote!(,).to_tokens(t); + } + if self.omitted_bindings() { + quote!(..).to_tokens(t); + } + }), + } + t + } + + /// Generates the token stream required to construct the current variant. + /// + /// The init array initializes each of the fields in the order they are + /// written in `variant.ast().fields`. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B(usize, usize), + /// C{ v: usize }, + /// } + /// }; + /// let s = Structure::new(&di); + /// + /// assert_eq!( + /// s.variants()[0].construct(|_, i| quote!(#i)).to_string(), + /// + /// quote!{ + /// A::B(0usize, 1usize,) + /// }.to_string() + /// ); + /// + /// assert_eq!( + /// s.variants()[1].construct(|_, i| quote!(#i)).to_string(), + /// + /// quote!{ + /// A::C{ v: 0usize, } + /// }.to_string() + /// ); + /// ``` + pub fn construct<F, T>(&self, mut func: F) -> TokenStream + where + F: FnMut(&Field, usize) -> T, + T: ToTokens, + { + let mut t = TokenStream::new(); + if let Some(prefix) = self.prefix { + quote!(#prefix ::).to_tokens(&mut t); + } + self.ast.ident.to_tokens(&mut t); + + match &self.ast.fields { + Fields::Unit => (), + Fields::Unnamed(FieldsUnnamed { unnamed, .. }) => { + token::Paren::default().surround(&mut t, |t| { + for (i, field) in unnamed.into_iter().enumerate() { + func(field, i).to_tokens(t); + quote!(,).to_tokens(t); + } + }) + } + Fields::Named(FieldsNamed { named, .. }) => { + token::Brace::default().surround(&mut t, |t| { + for (i, field) in named.into_iter().enumerate() { + field.ident.to_tokens(t); + quote!(:).to_tokens(t); + func(field, i).to_tokens(t); + quote!(,).to_tokens(t); + } + }) + } + } + t + } + + /// Runs the passed-in function once for each bound field, passing in a `BindingInfo`. + /// and generating a `match` arm which evaluates the returned tokens. + /// + /// This method will ignore fields which are ignored through the `filter` + /// method. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B(i32, i32), + /// C(u32), + /// } + /// }; + /// let s = Structure::new(&di); + /// + /// assert_eq!( + /// s.variants()[0].each(|bi| quote!(println!("{:?}", #bi))).to_string(), + /// + /// quote!{ + /// A::B(ref __binding_0, ref __binding_1,) => { + /// { println!("{:?}", __binding_0) } + /// { println!("{:?}", __binding_1) } + /// } + /// }.to_string() + /// ); + /// ``` + pub fn each<F, R>(&self, mut f: F) -> TokenStream + where + F: FnMut(&BindingInfo<'_>) -> R, + R: ToTokens, + { + let pat = self.pat(); + let mut body = TokenStream::new(); + for binding in &self.bindings { + token::Brace::default().surround(&mut body, |body| { + f(binding).to_tokens(body); + }); + } + quote!(#pat => { #body }) + } + + /// Runs the passed-in function once for each bound field, passing in the + /// result of the previous call, and a `BindingInfo`. generating a `match` + /// arm which evaluates to the resulting tokens. + /// + /// This method will ignore fields which are ignored through the `filter` + /// method. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B(i32, i32), + /// C(u32), + /// } + /// }; + /// let s = Structure::new(&di); + /// + /// assert_eq!( + /// s.variants()[0].fold(quote!(0), |acc, bi| quote!(#acc + #bi)).to_string(), + /// + /// quote!{ + /// A::B(ref __binding_0, ref __binding_1,) => { + /// 0 + __binding_0 + __binding_1 + /// } + /// }.to_string() + /// ); + /// ``` + pub fn fold<F, I, R>(&self, init: I, mut f: F) -> TokenStream + where + F: FnMut(TokenStream, &BindingInfo<'_>) -> R, + I: ToTokens, + R: ToTokens, + { + let pat = self.pat(); + let body = self.bindings.iter().fold(quote!(#init), |i, bi| { + let r = f(i, bi); + quote!(#r) + }); + quote!(#pat => { #body }) + } + + /// Filter the bindings created by this `Variant` object. This has 2 effects: + /// + /// * The bindings will no longer appear in match arms generated by methods + /// on this `Variant` or its subobjects. + /// + /// * Impl blocks created with the `bound_impl` or `unsafe_bound_impl` + /// method only consider type parameters referenced in the types of + /// non-filtered fields. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B{ a: i32, b: i32 }, + /// C{ a: u32 }, + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// s.variants_mut()[0].filter(|bi| { + /// bi.ast().ident == Some(quote::format_ident!("b")) + /// }); + /// + /// assert_eq!( + /// s.each(|bi| quote!(println!("{:?}", #bi))).to_string(), + /// + /// quote!{ + /// A::B{ b: ref __binding_1, .. } => { + /// { println!("{:?}", __binding_1) } + /// } + /// A::C{ a: ref __binding_0, } => { + /// { println!("{:?}", __binding_0) } + /// } + /// }.to_string() + /// ); + /// ``` + pub fn filter<F>(&mut self, f: F) -> &mut Self + where + F: FnMut(&BindingInfo<'_>) -> bool, + { + self.bindings.retain(f); + self + } + + /// Remove the binding at the given index. + /// + /// # Panics + /// + /// Panics if the index is out of range. + pub fn remove_binding(&mut self, idx: usize) -> &mut Self { + self.bindings.remove(idx); + self + } + + /// Updates the `BindStyle` for each of the passed-in fields by calling the + /// passed-in function for each `BindingInfo`. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B(i32, i32), + /// C(u32), + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// s.variants_mut()[0].bind_with(|bi| BindStyle::RefMut); + /// + /// assert_eq!( + /// s.each(|bi| quote!(println!("{:?}", #bi))).to_string(), + /// + /// quote!{ + /// A::B(ref mut __binding_0, ref mut __binding_1,) => { + /// { println!("{:?}", __binding_0) } + /// { println!("{:?}", __binding_1) } + /// } + /// A::C(ref __binding_0,) => { + /// { println!("{:?}", __binding_0) } + /// } + /// }.to_string() + /// ); + /// ``` + pub fn bind_with<F>(&mut self, mut f: F) -> &mut Self + where + F: FnMut(&BindingInfo<'_>) -> BindStyle, + { + for binding in &mut self.bindings { + binding.style = f(&binding); + } + self + } + + /// Updates the binding name for each fo the passed-in fields by calling the + /// passed-in function for each `BindingInfo`. + /// + /// The function will be called with the `BindingInfo` and its index in the + /// enclosing variant. + /// + /// The default name is `__binding_{}` where `{}` is replaced with an + /// increasing number. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B{ a: i32, b: i32 }, + /// C{ a: u32 }, + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// s.variants_mut()[0].binding_name(|bi, i| bi.ident.clone().unwrap()); + /// + /// assert_eq!( + /// s.each(|bi| quote!(println!("{:?}", #bi))).to_string(), + /// + /// quote!{ + /// A::B{ a: ref a, b: ref b, } => { + /// { println!("{:?}", a) } + /// { println!("{:?}", b) } + /// } + /// A::C{ a: ref __binding_0, } => { + /// { println!("{:?}", __binding_0) } + /// } + /// }.to_string() + /// ); + /// ``` + pub fn binding_name<F>(&mut self, mut f: F) -> &mut Self + where + F: FnMut(&Field, usize) -> Ident, + { + for (it, binding) in self.bindings.iter_mut().enumerate() { + binding.binding = f(binding.field, it); + } + self + } + + /// Returns a list of the type parameters which are referenced in this + /// field's type. + /// + /// # Caveat + /// + /// If the field contains any macros in type position, all parameters will + /// be considered bound. This is because we cannot determine which type + /// parameters are bound by type macros. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// struct A<T, U> { + /// a: Option<T>, + /// b: U, + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// assert_eq!( + /// s.variants()[0].bindings()[0].referenced_ty_params(), + /// &["e::format_ident!("T")] + /// ); + /// ``` + pub fn referenced_ty_params(&self) -> Vec<&'a Ident> { + let mut flags = Vec::new(); + for binding in &self.bindings { + generics_fuse(&mut flags, &binding.seen_generics); + } + fetch_generics(&flags, self.generics) + } +} + +/// A wrapper around a `syn::DeriveInput` which provides utilities for creating +/// custom derive trait implementations. +#[derive(Debug, Clone, PartialEq, Eq, Hash)] +pub struct Structure<'a> { + variants: Vec<VariantInfo<'a>>, + omitted_variants: bool, + underscore_const: bool, + ast: &'a DeriveInput, + extra_impl: Vec<GenericParam>, + extra_predicates: Vec<WherePredicate>, + add_bounds: AddBounds, +} + +impl<'a> Structure<'a> { + /// Create a new `Structure` with the variants and fields from the passed-in + /// `DeriveInput`. + /// + /// # Panics + /// + /// This method will panic if the provided AST node represents an untagged + /// union. + pub fn new(ast: &'a DeriveInput) -> Self { + Self::try_new(ast).expect("Unable to create synstructure::Structure") + } + + /// Create a new `Structure` with the variants and fields from the passed-in + /// `DeriveInput`. + /// + /// Unlike `Structure::new`, this method does not panic if the provided AST + /// node represents an untagged union. + pub fn try_new(ast: &'a DeriveInput) -> Result<Self> { + let variants = match &ast.data { + Data::Enum(data) => (&data.variants) + .into_iter() + .map(|v| { + VariantInfo::new( + VariantAst { + attrs: &v.attrs, + ident: &v.ident, + fields: &v.fields, + discriminant: &v.discriminant, + }, + Some(&ast.ident), + &ast.generics, + ) + }) + .collect::<Vec<_>>(), + Data::Struct(data) => { + // SAFETY NOTE: Normally putting an `Expr` in static storage + // wouldn't be safe, because it could contain `Term` objects + // which use thread-local interning. However, this static always + // contains the value `None`. Thus, it will never contain any + // unsafe values. + struct UnsafeMakeSync(Option<(token::Eq, Expr)>); + unsafe impl Sync for UnsafeMakeSync {} + static NONE_DISCRIMINANT: UnsafeMakeSync = UnsafeMakeSync(None); + + vec![VariantInfo::new( + VariantAst { + attrs: &ast.attrs, + ident: &ast.ident, + fields: &data.fields, + discriminant: &NONE_DISCRIMINANT.0, + }, + None, + &ast.generics, + )] + } + Data::Union(_) => { + return Err(Error::new_spanned( + ast, + "unexpected unsupported untagged union", + )); + } + }; + + Ok(Structure { + variants, + omitted_variants: false, + underscore_const: false, + ast, + extra_impl: vec![], + extra_predicates: vec![], + add_bounds: AddBounds::Both, + }) + } + + /// Returns a slice of the variants in this Structure. + pub fn variants(&self) -> &[VariantInfo<'a>] { + &self.variants + } + + /// Returns a mut slice of the variants in this Structure. + pub fn variants_mut(&mut self) -> &mut [VariantInfo<'a>] { + &mut self.variants + } + + /// Returns a reference to the underlying `syn` AST node which this + /// `Structure` was created from. + pub fn ast(&self) -> &'a DeriveInput { + self.ast + } + + /// True if any variants were omitted due to a `filter_variants` call. + pub fn omitted_variants(&self) -> bool { + self.omitted_variants + } + + /// Runs the passed-in function once for each bound field, passing in a `BindingInfo`. + /// and generating `match` arms which evaluate the returned tokens. + /// + /// This method will ignore variants or fields which are ignored through the + /// `filter` and `filter_variant` methods. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B(i32, i32), + /// C(u32), + /// } + /// }; + /// let s = Structure::new(&di); + /// + /// assert_eq!( + /// s.each(|bi| quote!(println!("{:?}", #bi))).to_string(), + /// + /// quote!{ + /// A::B(ref __binding_0, ref __binding_1,) => { + /// { println!("{:?}", __binding_0) } + /// { println!("{:?}", __binding_1) } + /// } + /// A::C(ref __binding_0,) => { + /// { println!("{:?}", __binding_0) } + /// } + /// }.to_string() + /// ); + /// ``` + pub fn each<F, R>(&self, mut f: F) -> TokenStream + where + F: FnMut(&BindingInfo<'_>) -> R, + R: ToTokens, + { + let mut t = TokenStream::new(); + for variant in &self.variants { + variant.each(&mut f).to_tokens(&mut t); + } + if self.omitted_variants { + quote!(_ => {}).to_tokens(&mut t); + } + t + } + + /// Runs the passed-in function once for each bound field, passing in the + /// result of the previous call, and a `BindingInfo`. generating `match` + /// arms which evaluate to the resulting tokens. + /// + /// This method will ignore variants or fields which are ignored through the + /// `filter` and `filter_variant` methods. + /// + /// If a variant has been ignored, it will return the `init` value. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B(i32, i32), + /// C(u32), + /// } + /// }; + /// let s = Structure::new(&di); + /// + /// assert_eq!( + /// s.fold(quote!(0), |acc, bi| quote!(#acc + #bi)).to_string(), + /// + /// quote!{ + /// A::B(ref __binding_0, ref __binding_1,) => { + /// 0 + __binding_0 + __binding_1 + /// } + /// A::C(ref __binding_0,) => { + /// 0 + __binding_0 + /// } + /// }.to_string() + /// ); + /// ``` + pub fn fold<F, I, R>(&self, init: I, mut f: F) -> TokenStream + where + F: FnMut(TokenStream, &BindingInfo<'_>) -> R, + I: ToTokens, + R: ToTokens, + { + let mut t = TokenStream::new(); + for variant in &self.variants { + variant.fold(&init, &mut f).to_tokens(&mut t); + } + if self.omitted_variants { + quote!(_ => { #init }).to_tokens(&mut t); + } + t + } + + /// Runs the passed-in function once for each variant, passing in a + /// `VariantInfo`. and generating `match` arms which evaluate the returned + /// tokens. + /// + /// This method will ignore variants and not bind fields which are ignored + /// through the `filter` and `filter_variant` methods. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B(i32, i32), + /// C(u32), + /// } + /// }; + /// let s = Structure::new(&di); + /// + /// assert_eq!( + /// s.each_variant(|v| { + /// let name = &v.ast().ident; + /// quote!(println!(stringify!(#name))) + /// }).to_string(), + /// + /// quote!{ + /// A::B(ref __binding_0, ref __binding_1,) => { + /// println!(stringify!(B)) + /// } + /// A::C(ref __binding_0,) => { + /// println!(stringify!(C)) + /// } + /// }.to_string() + /// ); + /// ``` + pub fn each_variant<F, R>(&self, mut f: F) -> TokenStream + where + F: FnMut(&VariantInfo<'_>) -> R, + R: ToTokens, + { + let mut t = TokenStream::new(); + for variant in &self.variants { + let pat = variant.pat(); + let body = f(variant); + quote!(#pat => { #body }).to_tokens(&mut t); + } + if self.omitted_variants { + quote!(_ => {}).to_tokens(&mut t); + } + t + } + + /// Filter the bindings created by this `Structure` object. This has 2 effects: + /// + /// * The bindings will no longer appear in match arms generated by methods + /// on this `Structure` or its subobjects. + /// + /// * Impl blocks created with the `bound_impl` or `unsafe_bound_impl` + /// method only consider type parameters referenced in the types of + /// non-filtered fields. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B{ a: i32, b: i32 }, + /// C{ a: u32 }, + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// s.filter(|bi| { + /// bi.ast().ident == Some(quote::format_ident!("a")) + /// }); + /// + /// assert_eq!( + /// s.each(|bi| quote!(println!("{:?}", #bi))).to_string(), + /// + /// quote!{ + /// A::B{ a: ref __binding_0, .. } => { + /// { println!("{:?}", __binding_0) } + /// } + /// A::C{ a: ref __binding_0, } => { + /// { println!("{:?}", __binding_0) } + /// } + /// }.to_string() + /// ); + /// ``` + pub fn filter<F>(&mut self, mut f: F) -> &mut Self + where + F: FnMut(&BindingInfo<'_>) -> bool, + { + for variant in &mut self.variants { + variant.filter(&mut f); + } + self + } + + /// Specify additional where predicate bounds which should be generated by + /// impl-generating functions such as `gen_impl`, `bound_impl`, and + /// `unsafe_bound_impl`. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A<T, U> { + /// B(T), + /// C(Option<U>), + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// // Add an additional where predicate. + /// s.add_where_predicate(syn::parse_quote!(T: std::fmt::Display)); + /// + /// assert_eq!( + /// s.bound_impl(quote!(krate::Trait), quote!{ + /// fn a() {} + /// }).to_string(), + /// quote!{ + /// #[allow(non_upper_case_globals)] + /// #[doc(hidden)] + /// const _DERIVE_krate_Trait_FOR_A: () = { + /// extern crate krate; + /// impl<T, U> krate::Trait for A<T, U> + /// where T: std::fmt::Display, + /// T: krate::Trait, + /// Option<U>: krate::Trait, + /// U: krate::Trait + /// { + /// fn a() {} + /// } + /// }; + /// }.to_string() + /// ); + /// ``` + pub fn add_where_predicate(&mut self, pred: WherePredicate) -> &mut Self { + self.extra_predicates.push(pred); + self + } + + /// Specify which bounds should be generated by impl-generating functions + /// such as `gen_impl`, `bound_impl`, and `unsafe_bound_impl`. + /// + /// The default behaviour is to generate both field and generic bounds from + /// type parameters. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A<T, U> { + /// B(T), + /// C(Option<U>), + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// // Limit bounds to only generics. + /// s.add_bounds(AddBounds::Generics); + /// + /// assert_eq!( + /// s.bound_impl(quote!(krate::Trait), quote!{ + /// fn a() {} + /// }).to_string(), + /// quote!{ + /// #[allow(non_upper_case_globals)] + /// #[doc(hidden)] + /// const _DERIVE_krate_Trait_FOR_A: () = { + /// extern crate krate; + /// impl<T, U> krate::Trait for A<T, U> + /// where T: krate::Trait, + /// U: krate::Trait + /// { + /// fn a() {} + /// } + /// }; + /// }.to_string() + /// ); + /// ``` + pub fn add_bounds(&mut self, mode: AddBounds) -> &mut Self { + self.add_bounds = mode; + self + } + + /// Filter the variants matched by this `Structure` object. This has 2 effects: + /// + /// * Match arms destructuring these variants will no longer be generated by + /// methods on this `Structure` + /// + /// * Impl blocks created with the `bound_impl` or `unsafe_bound_impl` + /// method only consider type parameters referenced in the types of + /// fields in non-fitered variants. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B(i32, i32), + /// C(u32), + /// } + /// }; + /// + /// let mut s = Structure::new(&di); + /// + /// s.filter_variants(|v| v.ast().ident != "B"); + /// + /// assert_eq!( + /// s.each(|bi| quote!(println!("{:?}", #bi))).to_string(), + /// + /// quote!{ + /// A::C(ref __binding_0,) => { + /// { println!("{:?}", __binding_0) } + /// } + /// _ => {} + /// }.to_string() + /// ); + /// ``` + pub fn filter_variants<F>(&mut self, f: F) -> &mut Self + where + F: FnMut(&VariantInfo<'_>) -> bool, + { + let before_len = self.variants.len(); + self.variants.retain(f); + if self.variants.len() != before_len { + self.omitted_variants = true; + } + self + } + + /// Remove the variant at the given index. + /// + /// # Panics + /// + /// Panics if the index is out of range. + pub fn remove_variant(&mut self, idx: usize) -> &mut Self { + self.variants.remove(idx); + self.omitted_variants = true; + self + } + + /// Updates the `BindStyle` for each of the passed-in fields by calling the + /// passed-in function for each `BindingInfo`. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B(i32, i32), + /// C(u32), + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// s.bind_with(|bi| BindStyle::RefMut); + /// + /// assert_eq!( + /// s.each(|bi| quote!(println!("{:?}", #bi))).to_string(), + /// + /// quote!{ + /// A::B(ref mut __binding_0, ref mut __binding_1,) => { + /// { println!("{:?}", __binding_0) } + /// { println!("{:?}", __binding_1) } + /// } + /// A::C(ref mut __binding_0,) => { + /// { println!("{:?}", __binding_0) } + /// } + /// }.to_string() + /// ); + /// ``` + pub fn bind_with<F>(&mut self, mut f: F) -> &mut Self + where + F: FnMut(&BindingInfo<'_>) -> BindStyle, + { + for variant in &mut self.variants { + variant.bind_with(&mut f); + } + self + } + + /// Updates the binding name for each fo the passed-in fields by calling the + /// passed-in function for each `BindingInfo`. + /// + /// The function will be called with the `BindingInfo` and its index in the + /// enclosing variant. + /// + /// The default name is `__binding_{}` where `{}` is replaced with an + /// increasing number. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A { + /// B{ a: i32, b: i32 }, + /// C{ a: u32 }, + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// s.binding_name(|bi, i| bi.ident.clone().unwrap()); + /// + /// assert_eq!( + /// s.each(|bi| quote!(println!("{:?}", #bi))).to_string(), + /// + /// quote!{ + /// A::B{ a: ref a, b: ref b, } => { + /// { println!("{:?}", a) } + /// { println!("{:?}", b) } + /// } + /// A::C{ a: ref a, } => { + /// { println!("{:?}", a) } + /// } + /// }.to_string() + /// ); + /// ``` + pub fn binding_name<F>(&mut self, mut f: F) -> &mut Self + where + F: FnMut(&Field, usize) -> Ident, + { + for variant in &mut self.variants { + variant.binding_name(&mut f); + } + self + } + + /// Returns a list of the type parameters which are refrenced in the types + /// of non-filtered fields / variants. + /// + /// # Caveat + /// + /// If the struct contains any macros in type position, all parameters will + /// be considered bound. This is because we cannot determine which type + /// parameters are bound by type macros. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A<T, U> { + /// B(T, i32), + /// C(Option<U>), + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// s.filter_variants(|v| v.ast().ident != "C"); + /// + /// assert_eq!( + /// s.referenced_ty_params(), + /// &["e::format_ident!("T")] + /// ); + /// ``` + pub fn referenced_ty_params(&self) -> Vec<&'a Ident> { + let mut flags = Vec::new(); + for variant in &self.variants { + for binding in &variant.bindings { + generics_fuse(&mut flags, &binding.seen_generics); + } + } + fetch_generics(&flags, &self.ast.generics) + } + + /// Adds an `impl<>` generic parameter. + /// This can be used when the trait to be derived needs some extra generic parameters. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A<T, U> { + /// B(T), + /// C(Option<U>), + /// } + /// }; + /// let mut s = Structure::new(&di); + /// let generic: syn::GenericParam = syn::parse_quote!(X: krate::AnotherTrait); + /// + /// assert_eq!( + /// s.add_impl_generic(generic) + /// .bound_impl(quote!(krate::Trait<X>), + /// quote!{ + /// fn a() {} + /// } + /// ).to_string(), + /// quote!{ + /// #[allow(non_upper_case_globals)] + /// #[doc(hidden)] + /// const _DERIVE_krate_Trait_X_FOR_A: () = { + /// extern crate krate; + /// impl<T, U, X: krate::AnotherTrait> krate::Trait<X> for A<T, U> + /// where T : krate :: Trait < X >, + /// Option<U>: krate::Trait<X>, + /// U: krate::Trait<X> + /// { + /// fn a() {} + /// } + /// }; + /// }.to_string() + /// ); + /// ``` + pub fn add_impl_generic(&mut self, param: GenericParam) -> &mut Self { + self.extra_impl.push(param); + self + } + + /// Add trait bounds for a trait with the given path for each type parmaeter + /// referenced in the types of non-filtered fields. + /// + /// # Caveat + /// + /// If the method contains any macros in type position, all parameters will + /// be considered bound. This is because we cannot determine which type + /// parameters are bound by type macros. + pub fn add_trait_bounds( + &self, + bound: &TraitBound, + where_clause: &mut Option<WhereClause>, + mode: AddBounds, + ) { + // If we have any explicit where predicates, make sure to add them first. + if !self.extra_predicates.is_empty() { + let clause = get_or_insert_with(&mut *where_clause, || WhereClause { + where_token: Default::default(), + predicates: punctuated::Punctuated::new(), + }); + clause + .predicates + .extend(self.extra_predicates.iter().cloned()); + } + + let mut seen = HashSet::new(); + let mut pred = |ty: Type| { + if !seen.contains(&ty) { + seen.insert(ty.clone()); + + // Add a predicate. + let clause = get_or_insert_with(&mut *where_clause, || WhereClause { + where_token: Default::default(), + predicates: punctuated::Punctuated::new(), + }); + clause.predicates.push(WherePredicate::Type(PredicateType { + lifetimes: None, + bounded_ty: ty, + colon_token: Default::default(), + bounds: Some(punctuated::Pair::End(TypeParamBound::Trait(bound.clone()))) + .into_iter() + .collect(), + })); + } + }; + + for variant in &self.variants { + for binding in &variant.bindings { + match mode { + AddBounds::Both | AddBounds::Fields => { + for &seen in &binding.seen_generics { + if seen { + pred(binding.ast().ty.clone()); + break; + } + } + } + _ => {} + } + + match mode { + AddBounds::Both | AddBounds::Generics => { + for param in binding.referenced_ty_params() { + pred(Type::Path(TypePath { + qself: None, + path: (*param).clone().into(), + })); + } + } + _ => {} + } + } + } + } + + /// Configure whether to use `const _` instead of a generated const name in + /// code generated by `gen_impl` and `bound_impl`. + /// + /// This syntax is only supported by rust 1.37, and later versions. + /// + /// Defaults to `false` for backwards compatibility reasons. + /// + /// # Example + /// + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// struct MyStruct; + /// }; + /// let mut s = Structure::new(&di); + /// + /// assert_eq!( + /// s.underscore_const(true) + /// .gen_impl(quote! { gen impl Trait for @Self { } }) + /// .to_string(), + /// quote! { + /// const _: () = { + /// impl Trait for MyStruct { } + /// }; + /// } + /// .to_string() + /// ); + /// + /// assert_eq!( + /// s.underscore_const(false) + /// .gen_impl(quote! { gen impl Trait for @Self { } }) + /// .to_string(), + /// quote! { + /// #[allow(non_upper_case_globals)] + /// const _DERIVE_Trait_FOR_MyStruct: () = { + /// impl Trait for MyStruct { } + /// }; + /// } + /// .to_string() + /// ); + /// ``` + pub fn underscore_const(&mut self, enabled: bool) -> &mut Self { + self.underscore_const = enabled; + self + } + + /// > NOTE: This methods' features are superceded by `Structure::gen_impl`. + /// + /// Creates an `impl` block with the required generic type fields filled in + /// to implement the trait `path`. + /// + /// This method also adds where clauses to the impl requiring that all + /// referenced type parmaeters implement the trait `path`. + /// + /// # Hygiene and Paths + /// + /// This method wraps the impl block inside of a `const` (see the example + /// below). In this scope, the first segment of the passed-in path is + /// `extern crate`-ed in. If you don't want to generate that `extern crate` + /// item, use a global path. + /// + /// This means that if you are implementing `my_crate::Trait`, you simply + /// write `s.bound_impl(quote!(my_crate::Trait), quote!(...))`, and for the + /// entirety of the definition, you can refer to your crate as `my_crate`. + /// + /// # Caveat + /// + /// If the method contains any macros in type position, all parameters will + /// be considered bound. This is because we cannot determine which type + /// parameters are bound by type macros. + /// + /// # Panics + /// + /// Panics if the path string parameter is not a valid `TraitBound`. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A<T, U> { + /// B(T), + /// C(Option<U>), + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// s.filter_variants(|v| v.ast().ident != "B"); + /// + /// assert_eq!( + /// s.bound_impl(quote!(krate::Trait), quote!{ + /// fn a() {} + /// }).to_string(), + /// quote!{ + /// #[allow(non_upper_case_globals)] + /// #[doc(hidden)] + /// const _DERIVE_krate_Trait_FOR_A: () = { + /// extern crate krate; + /// impl<T, U> krate::Trait for A<T, U> + /// where Option<U>: krate::Trait, + /// U: krate::Trait + /// { + /// fn a() {} + /// } + /// }; + /// }.to_string() + /// ); + /// ``` + pub fn bound_impl<P: ToTokens, B: ToTokens>(&self, path: P, body: B) -> TokenStream { + self.impl_internal( + path.into_token_stream(), + body.into_token_stream(), + quote!(), + None, + ) + } + + /// > NOTE: This methods' features are superceded by `Structure::gen_impl`. + /// + /// Creates an `impl` block with the required generic type fields filled in + /// to implement the unsafe trait `path`. + /// + /// This method also adds where clauses to the impl requiring that all + /// referenced type parmaeters implement the trait `path`. + /// + /// # Hygiene and Paths + /// + /// This method wraps the impl block inside of a `const` (see the example + /// below). In this scope, the first segment of the passed-in path is + /// `extern crate`-ed in. If you don't want to generate that `extern crate` + /// item, use a global path. + /// + /// This means that if you are implementing `my_crate::Trait`, you simply + /// write `s.bound_impl(quote!(my_crate::Trait), quote!(...))`, and for the + /// entirety of the definition, you can refer to your crate as `my_crate`. + /// + /// # Caveat + /// + /// If the method contains any macros in type position, all parameters will + /// be considered bound. This is because we cannot determine which type + /// parameters are bound by type macros. + /// + /// # Panics + /// + /// Panics if the path string parameter is not a valid `TraitBound`. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A<T, U> { + /// B(T), + /// C(Option<U>), + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// s.filter_variants(|v| v.ast().ident != "B"); + /// + /// assert_eq!( + /// s.unsafe_bound_impl(quote!(krate::Trait), quote!{ + /// fn a() {} + /// }).to_string(), + /// quote!{ + /// #[allow(non_upper_case_globals)] + /// #[doc(hidden)] + /// const _DERIVE_krate_Trait_FOR_A: () = { + /// extern crate krate; + /// unsafe impl<T, U> krate::Trait for A<T, U> + /// where Option<U>: krate::Trait, + /// U: krate::Trait + /// { + /// fn a() {} + /// } + /// }; + /// }.to_string() + /// ); + /// ``` + pub fn unsafe_bound_impl<P: ToTokens, B: ToTokens>(&self, path: P, body: B) -> TokenStream { + self.impl_internal( + path.into_token_stream(), + body.into_token_stream(), + quote!(unsafe), + None, + ) + } + + /// > NOTE: This methods' features are superceded by `Structure::gen_impl`. + /// + /// Creates an `impl` block with the required generic type fields filled in + /// to implement the trait `path`. + /// + /// This method will not add any where clauses to the impl. + /// + /// # Hygiene and Paths + /// + /// This method wraps the impl block inside of a `const` (see the example + /// below). In this scope, the first segment of the passed-in path is + /// `extern crate`-ed in. If you don't want to generate that `extern crate` + /// item, use a global path. + /// + /// This means that if you are implementing `my_crate::Trait`, you simply + /// write `s.bound_impl(quote!(my_crate::Trait), quote!(...))`, and for the + /// entirety of the definition, you can refer to your crate as `my_crate`. + /// + /// # Panics + /// + /// Panics if the path string parameter is not a valid `TraitBound`. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A<T, U> { + /// B(T), + /// C(Option<U>), + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// s.filter_variants(|v| v.ast().ident != "B"); + /// + /// assert_eq!( + /// s.unbound_impl(quote!(krate::Trait), quote!{ + /// fn a() {} + /// }).to_string(), + /// quote!{ + /// #[allow(non_upper_case_globals)] + /// #[doc(hidden)] + /// const _DERIVE_krate_Trait_FOR_A: () = { + /// extern crate krate; + /// impl<T, U> krate::Trait for A<T, U> { + /// fn a() {} + /// } + /// }; + /// }.to_string() + /// ); + /// ``` + pub fn unbound_impl<P: ToTokens, B: ToTokens>(&self, path: P, body: B) -> TokenStream { + self.impl_internal( + path.into_token_stream(), + body.into_token_stream(), + quote!(), + Some(AddBounds::None), + ) + } + + /// > NOTE: This methods' features are superceded by `Structure::gen_impl`. + /// + /// Creates an `impl` block with the required generic type fields filled in + /// to implement the unsafe trait `path`. + /// + /// This method will not add any where clauses to the impl. + /// + /// # Hygiene and Paths + /// + /// This method wraps the impl block inside of a `const` (see the example + /// below). In this scope, the first segment of the passed-in path is + /// `extern crate`-ed in. If you don't want to generate that `extern crate` + /// item, use a global path. + /// + /// This means that if you are implementing `my_crate::Trait`, you simply + /// write `s.bound_impl(quote!(my_crate::Trait), quote!(...))`, and for the + /// entirety of the definition, you can refer to your crate as `my_crate`. + /// + /// # Panics + /// + /// Panics if the path string parameter is not a valid `TraitBound`. + /// + /// # Example + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A<T, U> { + /// B(T), + /// C(Option<U>), + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// s.filter_variants(|v| v.ast().ident != "B"); + /// + /// assert_eq!( + /// s.unsafe_unbound_impl(quote!(krate::Trait), quote!{ + /// fn a() {} + /// }).to_string(), + /// quote!{ + /// #[allow(non_upper_case_globals)] + /// #[doc(hidden)] + /// const _DERIVE_krate_Trait_FOR_A: () = { + /// extern crate krate; + /// unsafe impl<T, U> krate::Trait for A<T, U> { + /// fn a() {} + /// } + /// }; + /// }.to_string() + /// ); + /// ``` + #[deprecated] + pub fn unsafe_unbound_impl<P: ToTokens, B: ToTokens>(&self, path: P, body: B) -> TokenStream { + self.impl_internal( + path.into_token_stream(), + body.into_token_stream(), + quote!(unsafe), + Some(AddBounds::None), + ) + } + + fn impl_internal( + &self, + path: TokenStream, + body: TokenStream, + safety: TokenStream, + mode: Option<AddBounds>, + ) -> TokenStream { + let mode = mode.unwrap_or(self.add_bounds); + let name = &self.ast.ident; + let mut gen_clone = self.ast.generics.clone(); + gen_clone.params.extend(self.extra_impl.clone().into_iter()); + let (impl_generics, _, _) = gen_clone.split_for_impl(); + let (_, ty_generics, where_clause) = self.ast.generics.split_for_impl(); + + let bound = syn::parse2::<TraitBound>(path) + .expect("`path` argument must be a valid rust trait bound"); + + let mut where_clause = where_clause.cloned(); + self.add_trait_bounds(&bound, &mut where_clause, mode); + + // This function is smart. If a global path is passed, no extern crate + // statement will be generated, however, a relative path will cause the + // crate which it is relative to to be imported within the current + // scope. + let mut extern_crate = quote!(); + if bound.path.leading_colon.is_none() { + if let Some(seg) = bound.path.segments.first() { + let seg = &seg.ident; + extern_crate = quote! { extern crate #seg; }; + } + } + + let generated = quote! { + #extern_crate + #safety impl #impl_generics #bound for #name #ty_generics #where_clause { + #body + } + }; + + if self.underscore_const { + quote! { + const _: () = { #generated }; + } + } else { + let dummy_const: Ident = sanitize_ident(&format!( + "_DERIVE_{}_FOR_{}", + (&bound).into_token_stream(), + name.into_token_stream(), + )); + quote! { + #[allow(non_upper_case_globals)] + #[doc(hidden)] + const #dummy_const: () = { + #generated + }; + } + } + } + + /// Generate an impl block for the given struct. This impl block will + /// automatically use hygiene tricks to avoid polluting the caller's + /// namespace, and will automatically add trait bounds for generic type + /// parameters. + /// + /// # Syntax + /// + /// This function accepts its arguments as a `TokenStream`. The recommended way + /// to call this function is passing the result of invoking the `quote!` + /// macro to it. + /// + /// ```ignore + /// s.gen_impl(quote! { + /// // You can write any items which you want to import into scope here. + /// // For example, you may want to include an `extern crate` for the + /// // crate which implements your trait. These items will only be + /// // visible to the code you generate, and won't be exposed to the + /// // consuming crate + /// extern crate krate; + /// + /// // You can also add `use` statements here to bring types or traits + /// // into scope. + /// // + /// // WARNING: Try not to use common names here, because the stable + /// // version of syn does not support hygiene and you could accidentally + /// // shadow types from the caller crate. + /// use krate::Trait as MyTrait; + /// + /// // The actual impl block is a `gen impl` or `gen unsafe impl` block. + /// // You can use `@Self` to refer to the structure's type. + /// gen impl MyTrait for @Self { + /// fn f(&self) { ... } + /// } + /// }) + /// ``` + /// + /// The most common usage of this trait involves loading the crate the + /// target trait comes from with `extern crate`, and then invoking a `gen + /// impl` block. + /// + /// # Hygiene + /// + /// This method tries to handle hygiene intelligenly for both stable and + /// unstable proc-macro implementations, however there are visible + /// differences. + /// + /// The output of every `gen_impl` function is wrapped in a dummy `const` + /// value, to ensure that it is given its own scope, and any values brought + /// into scope are not leaked to the calling crate. + /// + /// By default, the above invocation may generate an output like the + /// following: + /// + /// ```ignore + /// const _DERIVE_krate_Trait_FOR_Struct: () = { + /// extern crate krate; + /// use krate::Trait as MyTrait; + /// impl<T> MyTrait for Struct<T> where T: MyTrait { + /// fn f(&self) { ... } + /// } + /// }; + /// ``` + /// + /// The `Structure` may also be confired with the [`underscore_const`] method + /// to generate `const _` instead. + /// + /// ```ignore + /// const _: () = { + /// extern crate krate; + /// use krate::Trait as MyTrait; + /// impl<T> MyTrait for Struct<T> where T: MyTrait { + /// fn f(&self) { ... } + /// } + /// }; + /// ``` + /// + /// ### Using the `std` crate + /// + /// If you are using `quote!()` to implement your trait, with the + /// `proc-macro2/nightly` feature, `std` isn't considered to be in scope for + /// your macro. This means that if you use types from `std` in your + /// procedural macro, you'll want to explicitly load it with an `extern + /// crate std;`. + /// + /// ### Absolute paths + /// + /// You should generally avoid using absolute paths in your generated code, + /// as they will resolve very differently when using the stable and nightly + /// versions of `proc-macro2`. Instead, load the crates you need to use + /// explictly with `extern crate` and + /// + /// # Trait Bounds + /// + /// This method will automatically add trait bounds for any type parameters + /// which are referenced within the types of non-ignored fields. + /// + /// Additional type parameters may be added with the generics syntax after + /// the `impl` keyword. + /// + /// ### Type Macro Caveat + /// + /// If the method contains any macros in type position, all parameters will + /// be considered bound. This is because we cannot determine which type + /// parameters are bound by type macros. + /// + /// # Errors + /// + /// This function will generate a `compile_error!` if additional type + /// parameters added by `impl<..>` conflict with generic type parameters on + /// the original struct. + /// + /// # Panics + /// + /// This function will panic if the input `TokenStream` is not well-formed. + /// + /// # Example Usage + /// + /// ``` + /// # use synstructure::*; + /// let di: syn::DeriveInput = syn::parse_quote! { + /// enum A<T, U> { + /// B(T), + /// C(Option<U>), + /// } + /// }; + /// let mut s = Structure::new(&di); + /// + /// s.filter_variants(|v| v.ast().ident != "B"); + /// + /// assert_eq!( + /// s.gen_impl(quote! { + /// extern crate krate; + /// gen impl krate::Trait for @Self { + /// fn a() {} + /// } + /// }).to_string(), + /// quote!{ + /// #[allow(non_upper_case_globals)] + /// const _DERIVE_krate_Trait_FOR_A: () = { + /// extern crate krate; + /// impl<T, U> krate::Trait for A<T, U> + /// where + /// Option<U>: krate::Trait, + /// U: krate::Trait + /// { + /// fn a() {} + /// } + /// }; + /// }.to_string() + /// ); + /// + /// // NOTE: You can also add extra generics after the impl + /// assert_eq!( + /// s.gen_impl(quote! { + /// extern crate krate; + /// gen impl<X: krate::OtherTrait> krate::Trait<X> for @Self + /// where + /// X: Send + Sync, + /// { + /// fn a() {} + /// } + /// }).to_string(), + /// quote!{ + /// #[allow(non_upper_case_globals)] + /// const _DERIVE_krate_Trait_X_FOR_A: () = { + /// extern crate krate; + /// impl<X: krate::OtherTrait, T, U> krate::Trait<X> for A<T, U> + /// where + /// X: Send + Sync, + /// Option<U>: krate::Trait<X>, + /// U: krate::Trait<X> + /// { + /// fn a() {} + /// } + /// }; + /// }.to_string() + /// ); + /// + /// // NOTE: you can generate multiple traits with a single call + /// assert_eq!( + /// s.gen_impl(quote! { + /// extern crate krate; + /// + /// gen impl krate::Trait for @Self { + /// fn a() {} + /// } + /// + /// gen impl krate::OtherTrait for @Self { + /// fn b() {} + /// } + /// }).to_string(), + /// quote!{ + /// #[allow(non_upper_case_globals)] + /// const _DERIVE_krate_Trait_FOR_A: () = { + /// extern crate krate; + /// impl<T, U> krate::Trait for A<T, U> + /// where + /// Option<U>: krate::Trait, + /// U: krate::Trait + /// { + /// fn a() {} + /// } + /// + /// impl<T, U> krate::OtherTrait for A<T, U> + /// where + /// Option<U>: krate::OtherTrait, + /// U: krate::OtherTrait + /// { + /// fn b() {} + /// } + /// }; + /// }.to_string() + /// ); + /// ``` + /// + /// Use `add_bounds` to change which bounds are generated. + pub fn gen_impl(&self, cfg: TokenStream) -> TokenStream { + Parser::parse2( + |input: ParseStream<'_>| -> Result<TokenStream> { self.gen_impl_parse(input, true) }, + cfg, + ) + .expect("Failed to parse gen_impl") + } + + fn gen_impl_parse(&self, input: ParseStream<'_>, wrap: bool) -> Result<TokenStream> { + fn parse_prefix(input: ParseStream<'_>) -> Result<Option<Token![unsafe]>> { + if input.parse::<Ident>()? != "gen" { + return Err(input.error("Expected keyword `gen`")); + } + let safety = input.parse::<Option<Token![unsafe]>>()?; + let _ = input.parse::<Token![impl]>()?; + Ok(safety) + } + + let mut before = vec![]; + loop { + if parse_prefix(&input.fork()).is_ok() { + break; + } + before.push(input.parse::<TokenTree>()?); + } + + // Parse the prefix "for real" + let safety = parse_prefix(input)?; + + // optional `<>` + let mut generics = input.parse::<Generics>()?; + + // @bound + let bound = input.parse::<TraitBound>()?; + + // `for @Self` + let _ = input.parse::<Token![for]>()?; + let _ = input.parse::<Token![@]>()?; + let _ = input.parse::<Token![Self]>()?; + + // optional `where ...` + generics.where_clause = input.parse()?; + + // Body of the impl + let body; + braced!(body in input); + let body = body.parse::<TokenStream>()?; + + // Try to parse the next entry in sequence. If this fails, we'll fall + // back to just parsing the entire rest of the TokenStream. + let maybe_next_impl = self.gen_impl_parse(&input.fork(), false); + + // Eat tokens to the end. Whether or not our speculative nested parse + // succeeded, we're going to want to consume the rest of our input. + let mut after = input.parse::<TokenStream>()?; + if let Ok(stream) = maybe_next_impl { + after = stream; + } + assert!(input.is_empty(), "Should've consumed the rest of our input"); + + /* Codegen Logic */ + let name = &self.ast.ident; + + // Add the generics from the original struct in, and then add any + // additional trait bounds which we need on the type. + if let Err(err) = merge_generics(&mut generics, &self.ast.generics) { + // Report the merge error as a `compile_error!`, as it may be + // triggerable by an end-user. + return Ok(err.to_compile_error()); + } + + self.add_trait_bounds(&bound, &mut generics.where_clause, self.add_bounds); + let (impl_generics, _, where_clause) = generics.split_for_impl(); + let (_, ty_generics, _) = self.ast.generics.split_for_impl(); + + let generated = quote! { + #(#before)* + #safety impl #impl_generics #bound for #name #ty_generics #where_clause { + #body + } + #after + }; + + if wrap { + if self.underscore_const { + Ok(quote! { + const _: () = { #generated }; + }) + } else { + let dummy_const: Ident = sanitize_ident(&format!( + "_DERIVE_{}_FOR_{}", + (&bound).into_token_stream(), + name.into_token_stream(), + )); + Ok(quote! { + #[allow(non_upper_case_globals)] + const #dummy_const: () = { + #generated + }; + }) + } + } else { + Ok(generated) + } + } +} + +/// Dumps an unpretty version of a tokenstream. Takes any type which implements +/// `Display`. +/// +/// This is mostly useful for visualizing the output of a procedural macro, as +/// it makes it marginally more readable. It is used in the implementation of +/// `test_derive!` to unprettily print the output. +/// +/// # Stability +/// +/// The stability of the output of this function is not guaranteed. Do not +/// assert that the output of this function does not change between minor +/// versions. +/// +/// # Example +/// +/// ``` +/// # use quote::quote; +/// assert_eq!( +/// synstructure::unpretty_print(quote! { +/// #[allow(non_upper_case_globals)] +/// const _DERIVE_krate_Trait_FOR_A: () = { +/// extern crate krate; +/// impl<T, U> krate::Trait for A<T, U> +/// where +/// Option<U>: krate::Trait, +/// U: krate::Trait +/// { +/// fn a() {} +/// } +/// }; +/// }), +/// "# [ +/// allow ( +/// non_upper_case_globals ) +/// ] +/// const _DERIVE_krate_Trait_FOR_A : ( +/// ) +/// = { +/// extern crate krate ; +/// impl < T , U > krate :: Trait for A < T , U > where Option < U > : krate :: Trait , U : krate :: Trait { +/// fn a ( +/// ) +/// { +/// } +/// } +/// } +/// ; +/// " +/// ) +/// ``` +pub fn unpretty_print<T: std::fmt::Display>(ts: T) -> String { + let mut res = String::new(); + + let raw_s = ts.to_string(); + let mut s = &raw_s[..]; + let mut indent = 0; + while let Some(i) = s.find(&['(', '{', '[', ')', '}', ']', ';'][..]) { + match &s[i..=i] { + "(" | "{" | "[" => indent += 1, + ")" | "}" | "]" => indent -= 1, + _ => {} + } + res.push_str(&s[..=i]); + res.push('\n'); + for _ in 0..indent { + res.push_str(" "); + } + s = trim_start_matches(&s[i + 1..], ' '); + } + res.push_str(s); + res +} + +/// `trim_left_matches` has been deprecated in favor of `trim_start_matches`. +/// This helper silences the warning, as we need to continue using +/// `trim_left_matches` for rust 1.15 support. +#[allow(deprecated)] +fn trim_start_matches(s: &str, c: char) -> &str { + s.trim_left_matches(c) +} + +/// Helper trait describing values which may be returned by macro implementation +/// methods used by this crate's macros. +pub trait MacroResult { + /// Convert this result into a `Result` for further processing / validation. + fn into_result(self) -> Result<TokenStream>; + + /// Convert this result into a `proc_macro::TokenStream`, ready to return + /// from a native `proc_macro` implementation. + /// + /// If `into_result()` would return an `Err`, this method should instead + /// generate a `compile_error!` invocation to nicely report the error. + /// + /// *This method is available if `synstructure` is built with the + /// `"proc-macro"` feature.* + #[cfg(all( + not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "wasi"))), + feature = "proc-macro" + ))] + fn into_stream(self) -> proc_macro::TokenStream + where + Self: Sized, + { + match self.into_result() { + Ok(ts) => ts.into(), + Err(err) => err.to_compile_error().into(), + } + } +} + +#[cfg(all( + not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "wasi"))), + feature = "proc-macro" +))] +impl MacroResult for proc_macro::TokenStream { + fn into_result(self) -> Result<TokenStream> { + Ok(self.into()) + } + + fn into_stream(self) -> proc_macro::TokenStream { + self + } +} + +impl MacroResult for TokenStream { + fn into_result(self) -> Result<TokenStream> { + Ok(self) + } +} + +impl<T: MacroResult> MacroResult for Result<T> { + fn into_result(self) -> Result<TokenStream> { + match self { + Ok(v) => v.into_result(), + Err(err) => Err(err), + } + } +} + +#[cfg(test)] +mod tests { + use super::*; + + // Regression test for #48 + #[test] + fn test_each_enum() { + let di: syn::DeriveInput = syn::parse_quote! { + enum A { + Foo(usize, bool), + Bar(bool, usize), + Baz(usize, bool, usize), + Quux(bool, usize, bool) + } + }; + let mut s = Structure::new(&di); + + s.filter(|bi| bi.ast().ty.to_token_stream().to_string() == "bool"); + + assert_eq!( + s.each(|bi| quote!(do_something(#bi))).to_string(), + quote! { + A::Foo(_, ref __binding_1,) => { { do_something(__binding_1) } } + A::Bar(ref __binding_0, ..) => { { do_something(__binding_0) } } + A::Baz(_, ref __binding_1, ..) => { { do_something(__binding_1) } } + A::Quux(ref __binding_0, _, ref __binding_2,) => { + { + do_something(__binding_0) + } + { + do_something(__binding_2) + } + } + } + .to_string() + ); + } +} diff --git a/third_party/rust/synstructure/src/macros.rs b/third_party/rust/synstructure/src/macros.rs new file mode 100644 index 0000000000..5b6557b7c7 --- /dev/null +++ b/third_party/rust/synstructure/src/macros.rs @@ -0,0 +1,250 @@ +//! This module provides two utility macros for testing custom derives. They can +//! be used together to eliminate some of the boilerplate required in order to +//! declare and test custom derive implementations. + +// Re-exports used by the decl_derive! and test_derive! +pub use proc_macro2::TokenStream as TokenStream2; +pub use syn::{parse_str, DeriveInput}; + +#[cfg(all( + not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "wasi"))), + feature = "proc-macro" +))] +pub use proc_macro::TokenStream; +#[cfg(all( + not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "wasi"))), + feature = "proc-macro" +))] +pub use syn::parse; + +/// The `decl_derive!` macro declares a custom derive wrapper. It will parse the +/// incoming `TokenStream` into a `synstructure::Structure` object, and pass it +/// into the inner function. +/// +/// Your inner function should take a `synstructure::Structure` by value, and +/// return a type implementing `synstructure::MacroResult`, for example: +/// +/// ``` +/// fn derive_simple(input: synstructure::Structure) -> proc_macro2::TokenStream { +/// unimplemented!() +/// } +/// +/// fn derive_result(input: synstructure::Structure) +/// -> syn::Result<proc_macro2::TokenStream> +/// { +/// unimplemented!() +/// } +/// ``` +/// +/// # Usage +/// +/// ### Without Attributes +/// ``` +/// fn derive_interesting(_input: synstructure::Structure) -> proc_macro2::TokenStream { +/// quote::quote! { ... } +/// } +/// +/// # const _IGNORE: &'static str = stringify! { +/// decl_derive!([Interesting] => derive_interesting); +/// # }; +/// ``` +/// +/// ### With Attributes +/// ``` +/// # fn main() {} +/// fn derive_interesting(_input: synstructure::Structure) -> proc_macro2::TokenStream { +/// quote::quote! { ... } +/// } +/// +/// # const _IGNORE: &'static str = stringify! { +/// decl_derive!([Interesting, attributes(interesting_ignore)] => derive_interesting); +/// # }; +/// ``` +/// +/// ### Decl Attributes & Doc Comments +/// ``` +/// # fn main() {} +/// fn derive_interesting(_input: synstructure::Structure) -> proc_macro2::TokenStream { +/// quote::quote! { ... } +/// } +/// +/// # const _IGNORE: &'static str = stringify! { +/// decl_derive! { +/// [Interesting] => +/// #[allow(some_lint)] +/// /// Documentation Comments +/// derive_interesting +/// } +/// # }; +/// ``` +/// +/// *This macro is available if `synstructure` is built with the `"proc-macro"` +/// feature.* +#[cfg(all( + not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "wasi"))), + feature = "proc-macro" +))] +#[macro_export] +macro_rules! decl_derive { + // XXX: Switch to using this variant everywhere? + ([$derives:ident $($derive_t:tt)*] => $(#[$($attrs:tt)*])* $inner:path) => { + #[proc_macro_derive($derives $($derive_t)*)] + #[allow(non_snake_case)] + $(#[$($attrs)*])* + pub fn $derives( + i: $crate::macros::TokenStream + ) -> $crate::macros::TokenStream { + match $crate::macros::parse::<$crate::macros::DeriveInput>(i) { + Ok(p) => { + match $crate::Structure::try_new(&p) { + Ok(s) => $crate::MacroResult::into_stream($inner(s)), + Err(e) => e.to_compile_error().into(), + } + } + Err(e) => e.to_compile_error().into(), + } + } + }; +} + +/// The `decl_attribute!` macro declares a custom attribute wrapper. It will +/// parse the incoming `TokenStream` into a `synstructure::Structure` object, +/// and pass it into the inner function. +/// +/// Your inner function should have the following type: +/// +/// ``` +/// fn attribute( +/// attr: proc_macro2::TokenStream, +/// structure: synstructure::Structure, +/// ) -> proc_macro2::TokenStream { +/// unimplemented!() +/// } +/// ``` +/// +/// # Usage +/// +/// ``` +/// fn attribute_interesting( +/// _attr: proc_macro2::TokenStream, +/// _structure: synstructure::Structure, +/// ) -> proc_macro2::TokenStream { +/// quote::quote! { ... } +/// } +/// +/// # const _IGNORE: &'static str = stringify! { +/// decl_attribute!([interesting] => attribute_interesting); +/// # }; +/// ``` +/// +/// *This macro is available if `synstructure` is built with the `"proc-macro"` +/// feature.* +#[cfg(all( + not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "wasi"))), + feature = "proc-macro" +))] +#[macro_export] +macro_rules! decl_attribute { + ([$attribute:ident] => $(#[$($attrs:tt)*])* $inner:path) => { + #[proc_macro_attribute] + $(#[$($attrs)*])* + pub fn $attribute( + attr: $crate::macros::TokenStream, + i: $crate::macros::TokenStream, + ) -> $crate::macros::TokenStream { + match $crate::macros::parse::<$crate::macros::DeriveInput>(i) { + Ok(p) => match $crate::Structure::try_new(&p) { + Ok(s) => $crate::MacroResult::into_stream($inner(attr.into(), s)), + Err(e) => e.to_compile_error().into(), + }, + Err(e) => e.to_compile_error().into(), + } + } + }; +} + +/// Run a test on a custom derive. This macro expands both the original struct +/// and the expansion to ensure that they compile correctly, and confirms that +/// feeding the original struct into the named derive will produce the written +/// output. +/// +/// You can add `no_build` to the end of the macro invocation to disable +/// checking that the written code compiles. This is useful in contexts where +/// the procedural macro cannot depend on the crate where it is used during +/// tests. +/// +/// # Usage +/// +/// ``` +/// fn test_derive_example(_s: synstructure::Structure) +/// -> Result<proc_macro2::TokenStream, syn::Error> +/// { +/// Ok(quote::quote! { const YOUR_OUTPUT: &'static str = "here"; }) +/// } +/// +/// fn main() { +/// synstructure::test_derive!{ +/// test_derive_example { +/// struct A; +/// } +/// expands to { +/// const YOUR_OUTPUT: &'static str = "here"; +/// } +/// } +/// } +/// ``` +#[macro_export] +macro_rules! test_derive { + ($name:path { $($i:tt)* } expands to { $($o:tt)* }) => { + { + #[allow(dead_code)] + fn ensure_compiles() { + $($i)* + $($o)* + } + + $crate::test_derive!($name { $($i)* } expands to { $($o)* } no_build); + } + }; + + ($name:path { $($i:tt)* } expands to { $($o:tt)* } no_build) => { + { + let i = stringify!( $($i)* ); + let parsed = $crate::macros::parse_str::<$crate::macros::DeriveInput>(i) + .expect(concat!( + "Failed to parse input to `#[derive(", + stringify!($name), + ")]`", + )); + + let raw_res = $name($crate::Structure::new(&parsed)); + let res = $crate::MacroResult::into_result(raw_res) + .expect(concat!( + "Procedural macro failed for `#[derive(", + stringify!($name), + ")]`", + )); + + let expected = stringify!( $($o)* ) + .parse::<$crate::macros::TokenStream2>() + .expect("output should be a valid TokenStream"); + let mut expected_toks = $crate::macros::TokenStream2::from(expected); + if res.to_string() != expected_toks.to_string() { + panic!("\ +test_derive failed: +expected: +``` +{} +``` + +got: +``` +{} +```\n", + $crate::unpretty_print(&expected_toks), + $crate::unpretty_print(&res), + ); + } + } + }; +} |