1 // Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Some code that abstracts away much of the boilerplate of writing
12 //! `derive` instances for traits. Among other things it manages getting
13 //! access to the fields of the 4 different sorts of structs and enum
14 //! variants, as well as creating the method and impl ast instances.
16 //! Supported features (fairly exhaustive):
18 //! - Methods taking any number of parameters of any type, and returning
19 //! any type, other than vectors, bottom and closures.
20 //! - Generating `impl`s for types with type parameters and lifetimes
21 //! (e.g. `Option<T>`), the parameters are automatically given the
22 //! current trait as a bound. (This includes separate type parameters
23 //! and lifetimes for methods.)
24 //! - Additional bounds on the type parameters (`TraitDef.additional_bounds`)
26 //! The most important thing for implementers is the `Substructure` and
27 //! `SubstructureFields` objects. The latter groups 5 possibilities of the
30 //! - `Struct`, when `Self` is a struct (including tuple structs, e.g
31 //! `struct T(i32, char)`).
32 //! - `EnumMatching`, when `Self` is an enum and all the arguments are the
33 //! same variant of the enum (e.g. `Some(1)`, `Some(3)` and `Some(4)`)
34 //! - `EnumNonMatchingCollapsed` when `Self` is an enum and the arguments
35 //! are not the same variant (e.g. `None`, `Some(1)` and `None`).
36 //! - `StaticEnum` and `StaticStruct` for static methods, where the type
37 //! being derived upon is either an enum or struct respectively. (Any
38 //! argument with type Self is just grouped among the non-self
41 //! In the first two cases, the values from the corresponding fields in
42 //! all the arguments are grouped together. For `EnumNonMatchingCollapsed`
43 //! this isn't possible (different variants have different fields), so the
44 //! fields are inaccessible. (Previous versions of the deriving infrastructure
45 //! had a way to expand into code that could access them, at the cost of
46 //! generating exponential amounts of code; see issue #15375). There are no
47 //! fields with values in the static cases, so these are treated entirely
50 //! The non-static cases have `Option<ident>` in several places associated
51 //! with field `expr`s. This represents the name of the field it is
52 //! associated with. It is only not `None` when the associated field has
53 //! an identifier in the source code. For example, the `x`s in the
57 //! struct A { x : i32 }
67 //! The `i32`s in `B` and `C0` don't have an identifier, so the
68 //! `Option<ident>`s would be `None` for them.
70 //! In the static cases, the structure is summarised, either into the just
71 //! spans of the fields or a list of spans and the field idents (for tuple
72 //! structs and record structs, respectively), or a list of these, for
73 //! enums (one for each variant). For empty struct and empty enum
74 //! variants, it is represented as a count of 0.
76 //! # "`cs`" functions
78 //! The `cs_...` functions ("combine substructure) are designed to
79 //! make life easier by providing some pre-made recipes for common
80 //! threads; mostly calling the function being derived on all the
81 //! arguments and then combining them back together in some way (or
82 //! letting the user chose that). They are not meant to be the only
83 //! way to handle the structures that this code creates.
87 //! The following simplified `PartialEq` is used for in-code examples:
91 //! fn eq(&self, other: &Self);
93 //! impl PartialEq for i32 {
94 //! fn eq(&self, other: &i32) -> bool {
100 //! Some examples of the values of `SubstructureFields` follow, using the
101 //! above `PartialEq`, `A`, `B` and `C`.
105 //! When generating the `expr` for the `A` impl, the `SubstructureFields` is
108 //! Struct(vec![FieldInfo {
109 //! span: <span of x>
110 //! name: Some(<ident of x>),
111 //! self_: <expr for &self.x>,
112 //! other: vec![<expr for &other.x]
116 //! For the `B` impl, called with `B(a)` and `B(b)`,
119 //! Struct(vec![FieldInfo {
120 //! span: <span of `i32`>,
122 //! self_: <expr for &a>
123 //! other: vec![<expr for &b>]
129 //! When generating the `expr` for a call with `self == C0(a)` and `other
130 //! == C0(b)`, the SubstructureFields is
133 //! EnumMatching(0, <ast::Variant for C0>,
135 //! span: <span of i32>
137 //! self_: <expr for &a>,
138 //! other: vec![<expr for &b>]
142 //! For `C1 {x}` and `C1 {x}`,
145 //! EnumMatching(1, <ast::Variant for C1>,
147 //! span: <span of x>
148 //! name: Some(<ident of x>),
149 //! self_: <expr for &self.x>,
150 //! other: vec![<expr for &other.x>]
154 //! For `C0(a)` and `C1 {x}` ,
157 //! EnumNonMatchingCollapsed(
158 //! vec![<ident of self>, <ident of __arg_1>],
159 //! &[<ast::Variant for C0>, <ast::Variant for C1>],
160 //! &[<ident for self index value>, <ident of __arg_1 index value>])
163 //! It is the same for when the arguments are flipped to `C1 {x}` and
164 //! `C0(a)`; the only difference is what the values of the identifiers
165 //! <ident for self index value> and <ident of __arg_1 index value> will
166 //! be in the generated code.
168 //! `EnumNonMatchingCollapsed` deliberately provides far less information
169 //! than is generally available for a given pair of variants; see #15375
174 //! A static method on the types above would result in,
177 //! StaticStruct(<ast::StructDef of A>, Named(vec![(<ident of x>, <span of x>)]))
179 //! StaticStruct(<ast::StructDef of B>, Unnamed(vec![<span of x>]))
181 //! StaticEnum(<ast::EnumDef of C>,
182 //! vec![(<ident of C0>, <span of C0>, Unnamed(vec![<span of i32>])),
183 //! (<ident of C1>, <span of C1>, Named(vec![(<ident of x>, <span of x>)]))])
186 pub use self::StaticFields::*;
187 pub use self::SubstructureFields::*;
188 use self::StructType::*;
190 use std::cell::RefCell;
196 use ast::{EnumDef, Expr, Ident, Generics, StructDef};
199 use attr::AttrMetaMethods;
200 use ext::base::{ExtCtxt, Annotatable};
201 use ext::build::AstBuilder;
202 use codemap::{self, DUMMY_SP};
204 use diagnostic::SpanHandler;
206 use owned_slice::OwnedSlice;
207 use parse::token::InternedString;
208 use parse::token::special_idents;
211 use self::ty::{LifetimeBounds, Path, Ptr, PtrTy, Self_, Ty};
215 pub struct TraitDef<'a> {
216 /// The span for the current #[derive(Foo)] header.
219 pub attributes: Vec<ast::Attribute>,
221 /// Path of the trait, including any type parameters
224 /// Additional bounds required of any type parameters of the type,
225 /// other than the current trait
226 pub additional_bounds: Vec<Ty<'a>>,
228 /// Any extra lifetimes and/or bounds, e.g. `D: serialize::Decoder`
229 pub generics: LifetimeBounds<'a>,
231 pub methods: Vec<MethodDef<'a>>,
233 pub associated_types: Vec<(ast::Ident, Ty<'a>)>,
237 pub struct MethodDef<'a> {
238 /// name of the method
240 /// List of generics, e.g. `R: rand::Rng`
241 pub generics: LifetimeBounds<'a>,
243 /// Whether there is a self argument (outer Option) i.e. whether
244 /// this is a static function, and whether it is a pointer (inner
246 pub explicit_self: Option<Option<PtrTy<'a>>>,
248 /// Arguments other than the self argument
249 pub args: Vec<Ty<'a>>,
254 pub attributes: Vec<ast::Attribute>,
256 // Is it an `unsafe fn`?
259 pub combine_substructure: RefCell<CombineSubstructureFunc<'a>>,
262 /// All the data about the data structure/method being derived upon.
263 pub struct Substructure<'a> {
265 pub type_ident: Ident,
266 /// ident of the method
267 pub method_ident: Ident,
268 /// dereferenced access to any `Self_` or `Ptr(Self_, _)` arguments
269 pub self_args: &'a [P<Expr>],
270 /// verbatim access to any other arguments
271 pub nonself_args: &'a [P<Expr>],
272 pub fields: &'a SubstructureFields<'a>
275 /// Summary of the relevant parts of a struct/enum field.
276 pub struct FieldInfo<'a> {
278 /// None for tuple structs/normal enum variants, Some for normal
279 /// structs/struct enum variants.
280 pub name: Option<Ident>,
281 /// The expression corresponding to this field of `self`
282 /// (specifically, a reference to it).
284 /// The expressions corresponding to references to this field in
285 /// the other `Self` arguments.
286 pub other: Vec<P<Expr>>,
287 /// The attributes on the field
288 pub attrs: &'a [ast::Attribute],
291 /// Fields for a static method
292 pub enum StaticFields {
293 /// Tuple structs/enum variants like this.
295 /// Normal structs/struct variants.
296 Named(Vec<(Ident, Span)>),
299 /// A summary of the possible sets of fields.
300 pub enum SubstructureFields<'a> {
301 Struct(Vec<FieldInfo<'a>>),
302 /// Matching variants of the enum: variant index, ast::Variant,
303 /// fields: the field name is only non-`None` in the case of a struct
305 EnumMatching(usize, &'a ast::Variant, Vec<FieldInfo<'a>>),
307 /// Non-matching variants of the enum, but with all state hidden from
308 /// the consequent code. The first component holds `Ident`s for all of
309 /// the `Self` arguments; the second component is a slice of all of the
310 /// variants for the enum itself, and the third component is a list of
311 /// `Ident`s bound to the variant index values for each of the actual
312 /// input `Self` arguments.
313 EnumNonMatchingCollapsed(Vec<Ident>, &'a [P<ast::Variant>], &'a [Ident]),
315 /// A static method where `Self` is a struct.
316 StaticStruct(&'a ast::StructDef, StaticFields),
317 /// A static method where `Self` is an enum.
318 StaticEnum(&'a ast::EnumDef, Vec<(Ident, Span, StaticFields)>),
323 /// Combine the values of all the fields together. The last argument is
324 /// all the fields of all the structures.
325 pub type CombineSubstructureFunc<'a> =
326 Box<FnMut(&mut ExtCtxt, Span, &Substructure) -> P<Expr> + 'a>;
328 /// Deal with non-matching enum variants. The tuple is a list of
329 /// identifiers (one for each `Self` argument, which could be any of the
330 /// variants since they have been collapsed together) and the identifiers
331 /// holding the variant index value for each of the `Self` arguments. The
332 /// last argument is all the non-`Self` args of the method being derived.
333 pub type EnumNonMatchCollapsedFunc<'a> =
334 Box<FnMut(&mut ExtCtxt, Span, (&[Ident], &[Ident]), &[P<Expr>]) -> P<Expr> + 'a>;
336 pub fn combine_substructure<'a>(f: CombineSubstructureFunc<'a>)
337 -> RefCell<CombineSubstructureFunc<'a>> {
341 /// This method helps to extract all the type parameters referenced from a
342 /// type. For a type parameter `<T>`, it looks for either a `TyPath` that
343 /// is not global and starts with `T`, or a `TyQPath`.
344 fn find_type_parameters(ty: &ast::Ty, ty_param_names: &[ast::Name]) -> Vec<P<ast::Ty>> {
348 ty_param_names: &'a [ast::Name],
349 types: Vec<P<ast::Ty>>,
352 impl<'a> visit::Visitor<'a> for Visitor<'a> {
353 fn visit_ty(&mut self, ty: &'a ast::Ty) {
355 ast::TyPath(_, ref path) if !path.global => {
356 match path.segments.first() {
358 if self.ty_param_names.contains(&segment.identifier.name) {
359 self.types.push(P(ty.clone()));
368 visit::walk_ty(self, ty)
372 let mut visitor = Visitor {
373 ty_param_names: ty_param_names,
377 visit::Visitor::visit_ty(&mut visitor, ty);
382 impl<'a> TraitDef<'a> {
385 mitem: &ast::MetaItem,
386 item: &'a Annotatable,
387 push: &mut FnMut(Annotatable))
390 Annotatable::Item(ref item) => {
391 let newitem = match item.node {
392 ast::ItemStruct(ref struct_def, ref generics) => {
393 self.expand_struct_def(cx,
398 ast::ItemEnum(ref enum_def, ref generics) => {
399 self.expand_enum_def(cx,
406 cx.span_err(mitem.span,
407 "`derive` may only be applied to structs and enums");
411 // Keep the lint attributes of the previous item to control how the
412 // generated implementations are linted
413 let mut attrs = newitem.attrs.clone();
414 attrs.extend(item.attrs.iter().filter(|a| {
415 match &a.name()[..] {
416 "allow" | "warn" | "deny" | "forbid" => true,
420 push(Annotatable::Item(P(ast::Item {
426 cx.span_err(mitem.span, "`derive` may only be applied to structs and enums");
431 /// Given that we are deriving a trait `DerivedTrait` for a type like:
434 /// struct Struct<'a, ..., 'z, A, B: DeclaredTrait, C, ..., Z> where C: WhereTrait {
437 /// b1: <B as DeclaredTrait>::Item,
438 /// c1: <C as WhereTrait>::Item,
439 /// c2: Option<<C as WhereTrait>::Item>,
444 /// create an impl like:
447 /// impl<'a, ..., 'z, A, B: DeclaredTrait, C, ... Z> where
449 /// A: DerivedTrait + B1 + ... + BN,
450 /// B: DerivedTrait + B1 + ... + BN,
451 /// C: DerivedTrait + B1 + ... + BN,
452 /// B::Item: DerivedTrait + B1 + ... + BN,
453 /// <C as WhereTrait>::Item: DerivedTrait + B1 + ... + BN,
460 /// where B1, ..., BN are the bounds given by `bounds_paths`.'. Z is a phantom type, and
461 /// therefore does not get bound by the derived trait.
462 fn create_derived_impl(&self,
466 field_tys: Vec<P<ast::Ty>>,
467 methods: Vec<P<ast::ImplItem>>) -> P<ast::Item> {
468 let trait_path = self.path.to_path(cx, self.span, type_ident, generics);
470 // Transform associated types from `deriving::ty::Ty` into `ast::ImplItem`
471 let associated_types = self.associated_types.iter().map(|&(ident, ref type_def)| {
473 id: ast::DUMMY_NODE_ID,
478 node: ast::TypeImplItem(type_def.to_ty(cx,
486 let Generics { mut lifetimes, ty_params, mut where_clause } =
487 self.generics.to_generics(cx, self.span, type_ident, generics);
488 let mut ty_params = ty_params.into_vec();
490 // Copy the lifetimes
491 lifetimes.extend(generics.lifetimes.iter().cloned());
493 // Create the type parameters.
494 ty_params.extend(generics.ty_params.iter().map(|ty_param| {
495 // I don't think this can be moved out of the loop, since
496 // a TyParamBound requires an ast id
497 let mut bounds: Vec<_> =
498 // extra restrictions on the generics parameters to the type being derived upon
499 self.additional_bounds.iter().map(|p| {
500 cx.typarambound(p.to_path(cx, self.span,
501 type_ident, generics))
504 // require the current trait
505 bounds.push(cx.typarambound(trait_path.clone()));
507 // also add in any bounds from the declaration
508 for declared_bound in ty_param.bounds.iter() {
509 bounds.push((*declared_bound).clone());
512 cx.typaram(self.span,
514 OwnedSlice::from_vec(bounds),
518 // and similarly for where clauses
519 where_clause.predicates.extend(generics.where_clause.predicates.iter().map(|clause| {
521 ast::WherePredicate::BoundPredicate(ref wb) => {
522 ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
524 bound_lifetimes: wb.bound_lifetimes.clone(),
525 bounded_ty: wb.bounded_ty.clone(),
526 bounds: OwnedSlice::from_vec(wb.bounds.iter().cloned().collect())
529 ast::WherePredicate::RegionPredicate(ref rb) => {
530 ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
532 lifetime: rb.lifetime,
533 bounds: rb.bounds.iter().cloned().collect()
536 ast::WherePredicate::EqPredicate(ref we) => {
537 ast::WherePredicate::EqPredicate(ast::WhereEqPredicate {
538 id: ast::DUMMY_NODE_ID,
540 path: we.path.clone(),
547 if !ty_params.is_empty() {
548 let ty_param_names: Vec<ast::Name> = ty_params.iter()
549 .map(|ty_param| ty_param.ident.name)
552 for field_ty in field_tys {
553 let tys = find_type_parameters(&*field_ty, &ty_param_names);
556 let mut bounds: Vec<_> = self.additional_bounds.iter().map(|p| {
557 cx.typarambound(p.to_path(cx, self.span, type_ident, generics))
560 // require the current trait
561 bounds.push(cx.typarambound(trait_path.clone()));
563 let predicate = ast::WhereBoundPredicate {
565 bound_lifetimes: vec![],
567 bounds: OwnedSlice::from_vec(bounds),
570 let predicate = ast::WherePredicate::BoundPredicate(predicate);
571 where_clause.predicates.push(predicate);
576 let trait_generics = Generics {
577 lifetimes: lifetimes,
578 ty_params: OwnedSlice::from_vec(ty_params),
579 where_clause: where_clause
582 // Create the reference to the trait.
583 let trait_ref = cx.trait_ref(trait_path);
585 // Create the type parameters on the `self` path.
586 let self_ty_params = generics.ty_params.map(|ty_param| {
587 cx.ty_ident(self.span, ty_param.ident)
590 let self_lifetimes: Vec<ast::Lifetime> =
593 .map(|ld| ld.lifetime)
596 // Create the type of `self`.
597 let self_type = cx.ty_path(
598 cx.path_all(self.span, false, vec!( type_ident ), self_lifetimes,
599 self_ty_params.into_vec(), Vec::new()));
601 let attr = cx.attribute(
603 cx.meta_word(self.span,
604 InternedString::new("automatically_derived")));
605 // Just mark it now since we know that it'll end up used downstream
606 attr::mark_used(&attr);
607 let opt_trait_ref = Some(trait_ref);
608 let ident = ast_util::impl_pretty_name(&opt_trait_ref, Some(&*self_type));
609 let mut a = vec![attr];
610 a.extend(self.attributes.iter().cloned());
615 ast::ItemImpl(ast::Unsafety::Normal,
616 ast::ImplPolarity::Positive,
620 methods.into_iter().chain(associated_types).collect()))
623 fn expand_struct_def(&self,
625 struct_def: &'a StructDef,
627 generics: &Generics) -> P<ast::Item> {
628 let field_tys: Vec<P<ast::Ty>> = struct_def.fields.iter()
629 .map(|field| field.node.ty.clone())
632 let methods = self.methods.iter().map(|method_def| {
633 let (explicit_self, self_args, nonself_args, tys) =
634 method_def.split_self_nonself_args(
635 cx, self, type_ident, generics);
637 let body = if method_def.is_static() {
638 method_def.expand_static_struct_method_body(
646 method_def.expand_struct_method_body(cx,
654 method_def.create_method(cx,
664 self.create_derived_impl(cx, type_ident, generics, field_tys, methods)
667 fn expand_enum_def(&self,
669 enum_def: &'a EnumDef,
670 type_attrs: &[ast::Attribute],
672 generics: &Generics) -> P<ast::Item> {
673 let mut field_tys = Vec::new();
675 for variant in &enum_def.variants {
676 match variant.node.kind {
677 ast::VariantKind::TupleVariantKind(ref args) => {
678 field_tys.extend(args.iter()
679 .map(|arg| arg.ty.clone()));
681 ast::VariantKind::StructVariantKind(ref args) => {
682 field_tys.extend(args.fields.iter()
683 .map(|field| field.node.ty.clone()));
688 let methods = self.methods.iter().map(|method_def| {
689 let (explicit_self, self_args, nonself_args, tys) =
690 method_def.split_self_nonself_args(cx, self,
691 type_ident, generics);
693 let body = if method_def.is_static() {
694 method_def.expand_static_enum_method_body(
702 method_def.expand_enum_method_body(cx,
711 method_def.create_method(cx,
721 self.create_derived_impl(cx, type_ident, generics, field_tys, methods)
725 fn find_repr_type_name(diagnostic: &SpanHandler,
726 type_attrs: &[ast::Attribute]) -> &'static str {
727 let mut repr_type_name = "i32";
728 for a in type_attrs {
729 for r in &attr::find_repr_attrs(diagnostic, a) {
730 repr_type_name = match *r {
731 attr::ReprAny | attr::ReprPacked => continue,
732 attr::ReprExtern => "i32",
734 attr::ReprInt(_, attr::SignedInt(ast::TyIs)) => "isize",
735 attr::ReprInt(_, attr::SignedInt(ast::TyI8)) => "i8",
736 attr::ReprInt(_, attr::SignedInt(ast::TyI16)) => "i16",
737 attr::ReprInt(_, attr::SignedInt(ast::TyI32)) => "i32",
738 attr::ReprInt(_, attr::SignedInt(ast::TyI64)) => "i64",
740 attr::ReprInt(_, attr::UnsignedInt(ast::TyUs)) => "usize",
741 attr::ReprInt(_, attr::UnsignedInt(ast::TyU8)) => "u8",
742 attr::ReprInt(_, attr::UnsignedInt(ast::TyU16)) => "u16",
743 attr::ReprInt(_, attr::UnsignedInt(ast::TyU32)) => "u32",
744 attr::ReprInt(_, attr::UnsignedInt(ast::TyU64)) => "u64",
751 impl<'a> MethodDef<'a> {
752 fn call_substructure_method(&self,
756 self_args: &[P<Expr>],
757 nonself_args: &[P<Expr>],
758 fields: &SubstructureFields)
760 let substructure = Substructure {
761 type_ident: type_ident,
762 method_ident: cx.ident_of(self.name),
763 self_args: self_args,
764 nonself_args: nonself_args,
767 let mut f = self.combine_substructure.borrow_mut();
768 let f: &mut CombineSubstructureFunc = &mut *f;
769 f(cx, trait_.span, &substructure)
778 self.ret_ty.to_ty(cx, trait_.span, type_ident, generics)
781 fn is_static(&self) -> bool {
782 self.explicit_self.is_none()
785 fn split_self_nonself_args(&self,
790 -> (ast::ExplicitSelf, Vec<P<Expr>>, Vec<P<Expr>>, Vec<(Ident, P<ast::Ty>)>) {
792 let mut self_args = Vec::new();
793 let mut nonself_args = Vec::new();
794 let mut arg_tys = Vec::new();
795 let mut nonstatic = false;
797 let ast_explicit_self = match self.explicit_self {
798 Some(ref self_ptr) => {
799 let (self_expr, explicit_self) =
800 ty::get_explicit_self(cx, trait_.span, self_ptr);
802 self_args.push(self_expr);
807 None => codemap::respan(trait_.span, ast::SelfStatic),
810 for (i, ty) in self.args.iter().enumerate() {
811 let ast_ty = ty.to_ty(cx, trait_.span, type_ident, generics);
812 let ident = cx.ident_of(&format!("__arg_{}", i));
813 arg_tys.push((ident, ast_ty));
815 let arg_expr = cx.expr_ident(trait_.span, ident);
818 // for static methods, just treat any Self
819 // arguments as a normal arg
820 Self_ if nonstatic => {
821 self_args.push(arg_expr);
823 Ptr(ref ty, _) if **ty == Self_ && nonstatic => {
824 self_args.push(cx.expr_deref(trait_.span, arg_expr))
827 nonself_args.push(arg_expr);
832 (ast_explicit_self, self_args, nonself_args, arg_tys)
835 fn create_method(&self,
841 explicit_self: ast::ExplicitSelf,
842 arg_types: Vec<(Ident, P<ast::Ty>)> ,
843 body: P<Expr>) -> P<ast::ImplItem> {
844 // create the generics that aren't for Self
845 let fn_generics = self.generics.to_generics(cx, trait_.span, type_ident, generics);
847 let self_arg = match explicit_self.node {
848 ast::SelfStatic => None,
849 // creating fresh self id
850 _ => Some(ast::Arg::new_self(trait_.span, ast::MutImmutable, special_idents::self_))
853 let args = arg_types.into_iter().map(|(name, ty)| {
854 cx.arg(trait_.span, name, ty)
856 self_arg.into_iter().chain(args).collect()
859 let ret_type = self.get_ret_ty(cx, trait_, generics, type_ident);
861 let method_ident = cx.ident_of(self.name);
862 let fn_decl = cx.fn_decl(args, ret_type);
863 let body_block = cx.block_expr(body);
865 let unsafety = if self.is_unsafe {
866 ast::Unsafety::Unsafe
868 ast::Unsafety::Normal
871 // Create the method.
873 id: ast::DUMMY_NODE_ID,
874 attrs: self.attributes.clone(),
878 node: ast::MethodImplItem(ast::MethodSig {
879 generics: fn_generics,
881 explicit_self: explicit_self,
883 constness: ast::Constness::NotConst,
890 /// #[derive(PartialEq)]
891 /// struct A { x: i32, y: i32 }
893 /// // equivalent to:
894 /// impl PartialEq for A {
895 /// fn eq(&self, __arg_1: &A) -> bool {
897 /// A {x: ref __self_0_0, y: ref __self_0_1} => {
899 /// A {x: ref __self_1_0, y: ref __self_1_1} => {
900 /// __self_0_0.eq(__self_1_0) && __self_0_1.eq(__self_1_1)
908 fn expand_struct_method_body<'b>(&self,
910 trait_: &TraitDef<'b>,
911 struct_def: &'b StructDef,
913 self_args: &[P<Expr>],
914 nonself_args: &[P<Expr>])
917 let mut raw_fields = Vec::new(); // Vec<[fields of self],
918 // [fields of next Self arg], [etc]>
919 let mut patterns = Vec::new();
920 for i in 0..self_args.len() {
921 let struct_path= cx.path(DUMMY_SP, vec!( type_ident ));
922 let (pat, ident_expr) =
923 trait_.create_struct_pattern(cx,
926 &format!("__self_{}",
930 raw_fields.push(ident_expr);
933 // transpose raw_fields
934 let fields = if !raw_fields.is_empty() {
935 let mut raw_fields = raw_fields.into_iter().map(|v| v.into_iter());
936 let first_field = raw_fields.next().unwrap();
937 let mut other_fields: Vec<vec::IntoIter<_>>
938 = raw_fields.collect();
939 first_field.map(|(span, opt_id, field, attrs)| {
944 other: other_fields.iter_mut().map(|l| {
945 match l.next().unwrap() {
953 cx.span_bug(trait_.span,
954 "no self arguments to non-static method in generic \
958 // body of the inner most destructuring match
959 let mut body = self.call_substructure_method(
967 // make a series of nested matches, to destructure the
968 // structs. This is actually right-to-left, but it shouldn't
970 for (arg_expr, pat) in self_args.iter().zip(patterns) {
971 body = cx.expr_match(trait_.span, arg_expr.clone(),
972 vec!( cx.arm(trait_.span, vec!(pat.clone()), body) ))
977 fn expand_static_struct_method_body(&self,
980 struct_def: &StructDef,
982 self_args: &[P<Expr>],
983 nonself_args: &[P<Expr>])
985 let summary = trait_.summarise_struct(cx, struct_def);
987 self.call_substructure_method(cx,
990 self_args, nonself_args,
991 &StaticStruct(struct_def, summary))
995 /// #[derive(PartialEq)]
1001 /// // is equivalent to
1003 /// impl PartialEq for A {
1004 /// fn eq(&self, __arg_1: &A) -> ::bool {
1005 /// match (&*self, &*__arg_1) {
1006 /// (&A1, &A1) => true,
1007 /// (&A2(ref __self_0),
1008 /// &A2(ref __arg_1_0)) => (*__self_0).eq(&(*__arg_1_0)),
1010 /// let __self_vi = match *self { A1(..) => 0, A2(..) => 1 };
1011 /// let __arg_1_vi = match *__arg_1 { A1(..) => 0, A2(..) => 1 };
1019 /// (Of course `__self_vi` and `__arg_1_vi` are unused for
1020 /// `PartialEq`, and those subcomputations will hopefully be removed
1021 /// as their results are unused. The point of `__self_vi` and
1022 /// `__arg_1_vi` is for `PartialOrd`; see #15503.)
1023 fn expand_enum_method_body<'b>(&self,
1025 trait_: &TraitDef<'b>,
1026 enum_def: &'b EnumDef,
1027 type_attrs: &[ast::Attribute],
1029 self_args: Vec<P<Expr>>,
1030 nonself_args: &[P<Expr>])
1032 self.build_enum_match_tuple(
1033 cx, trait_, enum_def, type_attrs, type_ident, self_args, nonself_args)
1037 /// Creates a match for a tuple of all `self_args`, where either all
1038 /// variants match, or it falls into a catch-all for when one variant
1041 /// There are N + 1 cases because is a case for each of the N
1042 /// variants where all of the variants match, and one catch-all for
1043 /// when one does not match.
1045 /// The catch-all handler is provided access the variant index values
1046 /// for each of the self-args, carried in precomputed variables. (Nota
1047 /// bene: the variant index values are not necessarily the
1048 /// discriminant values. See issue #15523.)
1051 /// let __self0_vi = unsafe {
1052 /// std::intrinsics::discriminant_value(&self) } as i32;
1053 /// let __self1_vi = unsafe {
1054 /// std::intrinsics::discriminant_value(&__arg1) } as i32;
1055 /// let __self2_vi = unsafe {
1056 /// std::intrinsics::discriminant_value(&__arg2) } as i32;
1058 /// if __self0_vi == __self1_vi && __self0_vi == __self2_vi && ... {
1060 /// (Variant1, Variant1, ...) => Body1
1061 /// (Variant2, Variant2, ...) => Body2,
1063 /// _ => ::core::intrinsics::unreachable()
1067 /// ... // catch-all remainder can inspect above variant index values.
1070 fn build_enum_match_tuple<'b>(
1073 trait_: &TraitDef<'b>,
1074 enum_def: &'b EnumDef,
1075 type_attrs: &[ast::Attribute],
1077 self_args: Vec<P<Expr>>,
1078 nonself_args: &[P<Expr>]) -> P<Expr> {
1080 let sp = trait_.span;
1081 let variants = &enum_def.variants;
1083 let self_arg_names = self_args.iter().enumerate()
1084 .map(|(arg_count, _self_arg)| {
1086 "__self".to_string()
1088 format!("__arg_{}", arg_count)
1091 .collect::<Vec<String>>();
1093 let self_arg_idents = self_arg_names.iter()
1094 .map(|name|cx.ident_of(&name[..]))
1095 .collect::<Vec<ast::Ident>>();
1097 // The `vi_idents` will be bound, solely in the catch-all, to
1098 // a series of let statements mapping each self_arg to an int
1099 // value corresponding to its discriminant.
1100 let vi_idents: Vec<ast::Ident> = self_arg_names.iter()
1101 .map(|name| { let vi_suffix = format!("{}_vi", &name[..]);
1102 cx.ident_of(&vi_suffix[..]) })
1103 .collect::<Vec<ast::Ident>>();
1105 // Builds, via callback to call_substructure_method, the
1106 // delegated expression that handles the catch-all case,
1107 // using `__variants_tuple` to drive logic if necessary.
1108 let catch_all_substructure = EnumNonMatchingCollapsed(
1109 self_arg_idents, &variants[..], &vi_idents[..]);
1111 // These arms are of the form:
1112 // (Variant1, Variant1, ...) => Body1
1113 // (Variant2, Variant2, ...) => Body2
1115 // where each tuple has length = self_args.len()
1116 let mut match_arms: Vec<ast::Arm> = variants.iter().enumerate()
1117 .map(|(index, variant)| {
1118 let mk_self_pat = |cx: &mut ExtCtxt, self_arg_name: &str| {
1119 let (p, idents) = trait_.create_enum_variant_pattern(cx, type_ident,
1123 (cx.pat(sp, ast::PatRegion(p, ast::MutImmutable)), idents)
1126 // A single arm has form (&VariantK, &VariantK, ...) => BodyK
1127 // (see "Final wrinkle" note below for why.)
1128 let mut subpats = Vec::with_capacity(self_arg_names.len());
1129 let mut self_pats_idents = Vec::with_capacity(self_arg_names.len() - 1);
1130 let first_self_pat_idents = {
1131 let (p, idents) = mk_self_pat(cx, &self_arg_names[0]);
1135 for self_arg_name in &self_arg_names[1..] {
1136 let (p, idents) = mk_self_pat(cx, &self_arg_name[..]);
1138 self_pats_idents.push(idents);
1141 // Here is the pat = `(&VariantK, &VariantK, ...)`
1142 let single_pat = cx.pat_tuple(sp, subpats);
1144 // For the BodyK, we need to delegate to our caller,
1145 // passing it an EnumMatching to indicate which case
1148 // All of the Self args have the same variant in these
1149 // cases. So we transpose the info in self_pats_idents
1150 // to gather the getter expressions together, in the
1151 // form that EnumMatching expects.
1153 // The transposition is driven by walking across the
1154 // arg fields of the variant for the first self pat.
1155 let field_tuples = first_self_pat_idents.into_iter().enumerate()
1156 // For each arg field of self, pull out its getter expr ...
1157 .map(|(field_index, (sp, opt_ident, self_getter_expr, attrs))| {
1158 // ... but FieldInfo also wants getter expr
1159 // for matching other arguments of Self type;
1160 // so walk across the *other* self_pats_idents
1161 // and pull out getter for same field in each
1162 // of them (using `field_index` tracked above).
1163 // That is the heart of the transposition.
1164 let others = self_pats_idents.iter().map(|fields| {
1165 let (_, _opt_ident, ref other_getter_expr, _) =
1166 fields[field_index];
1168 // All Self args have same variant, so
1169 // opt_idents are the same. (Assert
1170 // here to make it self-evident that
1171 // it is okay to ignore `_opt_ident`.)
1172 assert!(opt_ident == _opt_ident);
1174 other_getter_expr.clone()
1175 }).collect::<Vec<P<Expr>>>();
1177 FieldInfo { span: sp,
1179 self_: self_getter_expr,
1183 }).collect::<Vec<FieldInfo>>();
1185 // Now, for some given VariantK, we have built up
1186 // expressions for referencing every field of every
1187 // Self arg, assuming all are instances of VariantK.
1188 // Build up code associated with such a case.
1189 let substructure = EnumMatching(index,
1192 let arm_expr = self.call_substructure_method(
1193 cx, trait_, type_ident, &self_args[..], nonself_args,
1196 cx.arm(sp, vec![single_pat], arm_expr)
1198 // We will usually need the catch-all after matching the
1199 // tuples `(VariantK, VariantK, ...)` for each VariantK of the
1202 // * when there is only one Self arg, the arms above suffice
1203 // (and the deriving we call back into may not be prepared to
1204 // handle EnumNonMatchCollapsed), and,
1206 // * when the enum has only one variant, the single arm that
1207 // is already present always suffices.
1209 // * In either of the two cases above, if we *did* add a
1210 // catch-all `_` match, it would trigger the
1211 // unreachable-pattern error.
1213 if variants.len() > 1 && self_args.len() > 1 {
1214 // Build a series of let statements mapping each self_arg
1215 // to its discriminant value. If this is a C-style enum
1216 // with a specific repr type, then casts the values to
1217 // that type. Otherwise casts to `i32` (the default repr
1220 // i.e. for `enum E<T> { A, B(1), C(T, T) }`, and a deriving
1221 // with three Self args, builds three statements:
1224 // let __self0_vi = unsafe {
1225 // std::intrinsics::discriminant_value(&self) } as i32;
1226 // let __self1_vi = unsafe {
1227 // std::intrinsics::discriminant_value(&__arg1) } as i32;
1228 // let __self2_vi = unsafe {
1229 // std::intrinsics::discriminant_value(&__arg2) } as i32;
1231 let mut index_let_stmts: Vec<P<ast::Stmt>> = Vec::new();
1233 //We also build an expression which checks whether all discriminants are equal
1234 // discriminant_test = __self0_vi == __self1_vi && __self0_vi == __self2_vi && ...
1235 let mut discriminant_test = cx.expr_bool(sp, true);
1237 let target_type_name =
1238 find_repr_type_name(&cx.parse_sess.span_diagnostic, type_attrs);
1240 let mut first_ident = None;
1241 for (&ident, self_arg) in vi_idents.iter().zip(&self_args) {
1242 let path = vec![cx.ident_of_std("core"),
1243 cx.ident_of("intrinsics"),
1244 cx.ident_of("discriminant_value")];
1245 let call = cx.expr_call_global(
1246 sp, path, vec![cx.expr_addr_of(sp, self_arg.clone())]);
1247 let variant_value = cx.expr_block(P(ast::Block {
1250 id: ast::DUMMY_NODE_ID,
1251 rules: ast::UnsafeBlock(ast::CompilerGenerated),
1254 let target_ty = cx.ty_ident(sp, cx.ident_of(target_type_name));
1255 let variant_disr = cx.expr_cast(sp, variant_value, target_ty);
1256 let let_stmt = cx.stmt_let(sp, false, ident, variant_disr);
1257 index_let_stmts.push(let_stmt);
1261 let first_expr = cx.expr_ident(sp, first);
1262 let id = cx.expr_ident(sp, ident);
1263 let test = cx.expr_binary(sp, ast::BiEq, first_expr, id);
1264 discriminant_test = cx.expr_binary(sp, ast::BiAnd, discriminant_test, test)
1267 first_ident = Some(ident);
1272 let arm_expr = self.call_substructure_method(
1273 cx, trait_, type_ident, &self_args[..], nonself_args,
1274 &catch_all_substructure);
1276 //Since we know that all the arguments will match if we reach the match expression we
1277 //add the unreachable intrinsics as the result of the catch all which should help llvm
1279 let path = vec![cx.ident_of_std("core"),
1280 cx.ident_of("intrinsics"),
1281 cx.ident_of("unreachable")];
1282 let call = cx.expr_call_global(
1284 let unreachable = cx.expr_block(P(ast::Block {
1287 id: ast::DUMMY_NODE_ID,
1288 rules: ast::UnsafeBlock(ast::CompilerGenerated),
1290 match_arms.push(cx.arm(sp, vec![cx.pat_wild(sp)], unreachable));
1292 // Final wrinkle: the self_args are expressions that deref
1293 // down to desired l-values, but we cannot actually deref
1294 // them when they are fed as r-values into a tuple
1295 // expression; here add a layer of borrowing, turning
1296 // `(*self, *__arg_0, ...)` into `(&*self, &*__arg_0, ...)`.
1297 let borrowed_self_args = self_args.move_map(|self_arg| cx.expr_addr_of(sp, self_arg));
1298 let match_arg = cx.expr(sp, ast::ExprTup(borrowed_self_args));
1300 //Lastly we create an expression which branches on all discriminants being equal
1301 // if discriminant_test {
1303 // (Variant1, Variant1, ...) => Body1
1304 // (Variant2, Variant2, ...) => Body2,
1306 // _ => ::core::intrinsics::unreachable()
1310 // <delegated expression referring to __self0_vi, et al.>
1312 let all_match = cx.expr_match(sp, match_arg, match_arms);
1313 let arm_expr = cx.expr_if(sp, discriminant_test, all_match, Some(arm_expr));
1315 cx.block_all(sp, index_let_stmts, Some(arm_expr)))
1316 } else if variants.is_empty() {
1317 // As an additional wrinkle, For a zero-variant enum A,
1318 // currently the compiler
1319 // will accept `fn (a: &Self) { match *a { } }`
1320 // but rejects `fn (a: &Self) { match (&*a,) { } }`
1321 // as well as `fn (a: &Self) { match ( *a,) { } }`
1323 // This means that the strategy of building up a tuple of
1324 // all Self arguments fails when Self is a zero variant
1325 // enum: rustc rejects the expanded program, even though
1326 // the actual code tends to be impossible to execute (at
1327 // least safely), according to the type system.
1329 // The most expedient fix for this is to just let the
1330 // code fall through to the catch-all. But even this is
1331 // error-prone, since the catch-all as defined above would
1332 // generate code like this:
1334 // _ => { let __self0 = match *self { };
1335 // let __self1 = match *__arg_0 { };
1336 // <catch-all-expr> }
1338 // Which is yields bindings for variables which type
1339 // inference cannot resolve to unique types.
1341 // One option to the above might be to add explicit type
1342 // annotations. But the *only* reason to go down that path
1343 // would be to try to make the expanded output consistent
1344 // with the case when the number of enum variants >= 1.
1346 // That just isn't worth it. In fact, trying to generate
1347 // sensible code for *any* deriving on a zero-variant enum
1348 // does not make sense. But at the same time, for now, we
1349 // do not want to cause a compile failure just because the
1350 // user happened to attach a deriving to their
1351 // zero-variant enum.
1353 // Instead, just generate a failing expression for the
1354 // zero variant case, skipping matches and also skipping
1355 // delegating back to the end user code entirely.
1357 // (See also #4499 and #12609; note that some of the
1358 // discussions there influence what choice we make here;
1359 // e.g. if we feature-gate `match x { ... }` when x refers
1360 // to an uninhabited type (e.g. a zero-variant enum or a
1361 // type holding such an enum), but do not feature-gate
1362 // zero-variant enums themselves, then attempting to
1363 // derive Debug on such a type could here generate code
1364 // that needs the feature gate enabled.)
1366 cx.expr_unreachable(sp)
1370 // Final wrinkle: the self_args are expressions that deref
1371 // down to desired l-values, but we cannot actually deref
1372 // them when they are fed as r-values into a tuple
1373 // expression; here add a layer of borrowing, turning
1374 // `(*self, *__arg_0, ...)` into `(&*self, &*__arg_0, ...)`.
1375 let borrowed_self_args = self_args.move_map(|self_arg| cx.expr_addr_of(sp, self_arg));
1376 let match_arg = cx.expr(sp, ast::ExprTup(borrowed_self_args));
1377 cx.expr_match(sp, match_arg, match_arms)
1381 fn expand_static_enum_method_body(&self,
1386 self_args: &[P<Expr>],
1387 nonself_args: &[P<Expr>])
1389 let summary = enum_def.variants.iter().map(|v| {
1390 let ident = v.node.name;
1391 let summary = match v.node.kind {
1392 ast::TupleVariantKind(ref args) => {
1393 Unnamed(args.iter().map(|va| trait_.set_expn_info(cx, va.ty.span)).collect())
1395 ast::StructVariantKind(ref struct_def) => {
1396 trait_.summarise_struct(cx, &**struct_def)
1399 (ident, v.span, summary)
1401 self.call_substructure_method(cx, trait_, type_ident,
1402 self_args, nonself_args,
1403 &StaticEnum(enum_def, summary))
1407 #[derive(PartialEq)] // dogfooding!
1409 Unknown, Record, Tuple
1412 // general helper methods.
1413 impl<'a> TraitDef<'a> {
1414 fn set_expn_info(&self,
1416 mut to_set: Span) -> Span {
1417 let trait_name = match self.path.path.last() {
1418 None => cx.span_bug(self.span, "trait with empty path in generic `derive`"),
1421 to_set.expn_id = cx.codemap().record_expansion(codemap::ExpnInfo {
1423 callee: codemap::NameAndSpan {
1424 name: format!("derive({})", trait_name),
1425 format: codemap::MacroAttribute,
1426 span: Some(self.span),
1427 allow_internal_unstable: false,
1433 fn summarise_struct(&self,
1435 struct_def: &StructDef) -> StaticFields {
1436 let mut named_idents = Vec::new();
1437 let mut just_spans = Vec::new();
1438 for field in struct_def.fields.iter(){
1439 let sp = self.set_expn_info(cx, field.span);
1440 match field.node.kind {
1441 ast::NamedField(ident, _) => named_idents.push((ident, sp)),
1442 ast::UnnamedField(..) => just_spans.push(sp),
1446 match (just_spans.is_empty(), named_idents.is_empty()) {
1447 (false, false) => cx.span_bug(self.span,
1448 "a struct with named and unnamed \
1449 fields in generic `derive`"),
1451 (_, false) => Named(named_idents),
1452 // tuple structs (includes empty structs)
1453 (_, _) => Unnamed(just_spans)
1457 fn create_subpatterns(&self,
1459 field_paths: Vec<ast::SpannedIdent> ,
1460 mutbl: ast::Mutability)
1461 -> Vec<P<ast::Pat>> {
1462 field_paths.iter().map(|path| {
1464 ast::PatIdent(ast::BindByRef(mutbl), (*path).clone(), None))
1468 fn create_struct_pattern(&self,
1470 struct_path: ast::Path,
1471 struct_def: &'a StructDef,
1473 mutbl: ast::Mutability)
1474 -> (P<ast::Pat>, Vec<(Span, Option<Ident>,
1476 &'a [ast::Attribute])>) {
1477 if struct_def.fields.is_empty() {
1478 return (cx.pat_enum(self.span, struct_path, vec![]), vec![]);
1481 let mut paths = Vec::new();
1482 let mut ident_expr = Vec::new();
1483 let mut struct_type = Unknown;
1485 for (i, struct_field) in struct_def.fields.iter().enumerate() {
1486 let sp = self.set_expn_info(cx, struct_field.span);
1487 let opt_id = match struct_field.node.kind {
1488 ast::NamedField(ident, _) if (struct_type == Unknown ||
1489 struct_type == Record) => {
1490 struct_type = Record;
1493 ast::UnnamedField(..) if (struct_type == Unknown ||
1494 struct_type == Tuple) => {
1495 struct_type = Tuple;
1499 cx.span_bug(sp, "a struct with named and unnamed fields in `derive`");
1502 let ident = cx.ident_of(&format!("{}_{}", prefix, i));
1503 paths.push(codemap::Spanned{span: sp, node: ident});
1505 sp, ast::ExprParen(cx.expr_deref(sp, cx.expr_path(cx.path_ident(sp,ident)))));
1506 ident_expr.push((sp, opt_id, val, &struct_field.node.attrs[..]));
1509 let subpats = self.create_subpatterns(cx, paths, mutbl);
1511 // struct_type is definitely not Unknown, since struct_def.fields
1512 // must be nonempty to reach here
1513 let pattern = if struct_type == Record {
1514 let field_pats = subpats.into_iter().zip(&ident_expr)
1515 .map(|(pat, &(_, id, _, _))| {
1516 // id is guaranteed to be Some
1519 node: ast::FieldPat { ident: id.unwrap(), pat: pat, is_shorthand: false },
1522 cx.pat_struct(self.span, struct_path, field_pats)
1524 cx.pat_enum(self.span, struct_path, subpats)
1527 (pattern, ident_expr)
1530 fn create_enum_variant_pattern(&self,
1532 enum_ident: ast::Ident,
1533 variant: &'a ast::Variant,
1535 mutbl: ast::Mutability)
1536 -> (P<ast::Pat>, Vec<(Span, Option<Ident>, P<Expr>, &'a [ast::Attribute])>) {
1537 let variant_ident = variant.node.name;
1538 let variant_path = cx.path(variant.span, vec![enum_ident, variant_ident]);
1539 match variant.node.kind {
1540 ast::TupleVariantKind(ref variant_args) => {
1541 if variant_args.is_empty() {
1542 return (cx.pat_enum(variant.span, variant_path, vec![]), vec![]);
1545 let mut paths = Vec::new();
1546 let mut ident_expr: Vec<(_, _, _, &'a [ast::Attribute])> = Vec::new();
1547 for (i, va) in variant_args.iter().enumerate() {
1548 let sp = self.set_expn_info(cx, va.ty.span);
1549 let ident = cx.ident_of(&format!("{}_{}", prefix, i));
1550 let path1 = codemap::Spanned{span: sp, node: ident};
1552 let expr_path = cx.expr_path(cx.path_ident(sp, ident));
1553 let val = cx.expr(sp, ast::ExprParen(cx.expr_deref(sp, expr_path)));
1554 ident_expr.push((sp, None, val, &[]));
1557 let subpats = self.create_subpatterns(cx, paths, mutbl);
1559 (cx.pat_enum(variant.span, variant_path, subpats),
1562 ast::StructVariantKind(ref struct_def) => {
1563 self.create_struct_pattern(cx, variant_path, &**struct_def,
1570 /* helpful premade recipes */
1572 /// Fold the fields. `use_foldl` controls whether this is done
1573 /// left-to-right (`true`) or right-to-left (`false`).
1574 pub fn cs_fold<F>(use_foldl: bool,
1577 mut enum_nonmatch_f: EnumNonMatchCollapsedFunc,
1580 substructure: &Substructure)
1582 F: FnMut(&mut ExtCtxt, Span, P<Expr>, P<Expr>, &[P<Expr>]) -> P<Expr>,
1584 match *substructure.fields {
1585 EnumMatching(_, _, ref all_fields) | Struct(ref all_fields) => {
1587 all_fields.iter().fold(base, |old, field| {
1591 field.self_.clone(),
1595 all_fields.iter().rev().fold(base, |old, field| {
1599 field.self_.clone(),
1604 EnumNonMatchingCollapsed(ref all_args, _, tuple) =>
1605 enum_nonmatch_f(cx, trait_span, (&all_args[..], tuple),
1606 substructure.nonself_args),
1607 StaticEnum(..) | StaticStruct(..) => {
1608 cx.span_bug(trait_span, "static function in `derive`")
1614 /// Call the method that is being derived on all the fields, and then
1615 /// process the collected results. i.e.
1618 /// f(cx, span, vec![self_1.method(__arg_1_1, __arg_2_1),
1619 /// self_2.method(__arg_1_2, __arg_2_2)])
1622 pub fn cs_same_method<F>(f: F,
1623 mut enum_nonmatch_f: EnumNonMatchCollapsedFunc,
1626 substructure: &Substructure)
1628 F: FnOnce(&mut ExtCtxt, Span, Vec<P<Expr>>) -> P<Expr>,
1630 match *substructure.fields {
1631 EnumMatching(_, _, ref all_fields) | Struct(ref all_fields) => {
1632 // call self_n.method(other_1_n, other_2_n, ...)
1633 let called = all_fields.iter().map(|field| {
1634 cx.expr_method_call(field.span,
1635 field.self_.clone(),
1636 substructure.method_ident,
1638 .map(|e| cx.expr_addr_of(field.span, e.clone()))
1642 f(cx, trait_span, called)
1644 EnumNonMatchingCollapsed(ref all_self_args, _, tuple) =>
1645 enum_nonmatch_f(cx, trait_span, (&all_self_args[..], tuple),
1646 substructure.nonself_args),
1647 StaticEnum(..) | StaticStruct(..) => {
1648 cx.span_bug(trait_span, "static function in `derive`")
1653 /// Fold together the results of calling the derived method on all the
1654 /// fields. `use_foldl` controls whether this is done left-to-right
1655 /// (`true`) or right-to-left (`false`).
1657 pub fn cs_same_method_fold<F>(use_foldl: bool,
1660 enum_nonmatch_f: EnumNonMatchCollapsedFunc,
1663 substructure: &Substructure)
1665 F: FnMut(&mut ExtCtxt, Span, P<Expr>, P<Expr>) -> P<Expr>,
1670 vals.into_iter().fold(base.clone(), |old, new| {
1671 f(cx, span, old, new)
1674 vals.into_iter().rev().fold(base.clone(), |old, new| {
1675 f(cx, span, old, new)
1680 cx, trait_span, substructure)
1683 /// Use a given binop to combine the result of calling the derived method
1684 /// on all the fields.
1686 pub fn cs_binop(binop: ast::BinOp_, base: P<Expr>,
1687 enum_nonmatch_f: EnumNonMatchCollapsedFunc,
1688 cx: &mut ExtCtxt, trait_span: Span,
1689 substructure: &Substructure) -> P<Expr> {
1690 cs_same_method_fold(
1691 true, // foldl is good enough
1692 |cx, span, old, new| {
1693 cx.expr_binary(span,
1700 cx, trait_span, substructure)
1703 /// cs_binop with binop == or
1705 pub fn cs_or(enum_nonmatch_f: EnumNonMatchCollapsedFunc,
1706 cx: &mut ExtCtxt, span: Span,
1707 substructure: &Substructure) -> P<Expr> {
1708 cs_binop(ast::BiOr, cx.expr_bool(span, false),
1710 cx, span, substructure)
1713 /// cs_binop with binop == and
1715 pub fn cs_and(enum_nonmatch_f: EnumNonMatchCollapsedFunc,
1716 cx: &mut ExtCtxt, span: Span,
1717 substructure: &Substructure) -> P<Expr> {
1718 cs_binop(ast::BiAnd, cx.expr_bool(span, true),
1720 cx, span, substructure)