diff options
Diffstat (limited to 'compiler/rustc_builtin_macros/src/deriving/encodable.rs')
| -rw-r--r-- | compiler/rustc_builtin_macros/src/deriving/encodable.rs | 284 |
1 files changed, 0 insertions, 284 deletions
diff --git a/compiler/rustc_builtin_macros/src/deriving/encodable.rs b/compiler/rustc_builtin_macros/src/deriving/encodable.rs deleted file mode 100644 index 20aacb2caca..00000000000 --- a/compiler/rustc_builtin_macros/src/deriving/encodable.rs +++ /dev/null @@ -1,284 +0,0 @@ -//! The compiler code necessary to implement the `#[derive(RustcEncodable)]` -//! (and `RustcDecodable`, in `decodable.rs`) extension. The idea here is that -//! type-defining items may be tagged with -//! `#[derive(RustcEncodable, RustcDecodable)]`. -//! -//! For example, a type like: -//! -//! ```ignore (old code) -//! #[derive(RustcEncodable, RustcDecodable)] -//! struct Node { id: usize } -//! ``` -//! -//! would generate two implementations like: -//! -//! ```ignore (old code) -//! # struct Node { id: usize } -//! impl<S: Encoder<E>, E> Encodable<S, E> for Node { -//! fn encode(&self, s: &mut S) -> Result<(), E> { -//! s.emit_struct("Node", 1, |this| { -//! this.emit_struct_field("id", 0, |this| { -//! Encodable::encode(&self.id, this) -//! /* this.emit_usize(self.id) can also be used */ -//! }) -//! }) -//! } -//! } -//! -//! impl<D: Decoder<E>, E> Decodable<D, E> for Node { -//! fn decode(d: &mut D) -> Result<Node, E> { -//! d.read_struct("Node", 1, |this| { -//! match this.read_struct_field("id", 0, |this| Decodable::decode(this)) { -//! Ok(id) => Ok(Node { id: id }), -//! Err(e) => Err(e), -//! } -//! }) -//! } -//! } -//! ``` -//! -//! Other interesting scenarios are when the item has type parameters or -//! references other non-built-in types. A type definition like: -//! -//! ```ignore (old code) -//! # #[derive(RustcEncodable, RustcDecodable)] -//! # struct Span; -//! #[derive(RustcEncodable, RustcDecodable)] -//! struct Spanned<T> { node: T, span: Span } -//! ``` -//! -//! would yield functions like: -//! -//! ```ignore (old code) -//! # #[derive(RustcEncodable, RustcDecodable)] -//! # struct Span; -//! # struct Spanned<T> { node: T, span: Span } -//! impl< -//! S: Encoder<E>, -//! E, -//! T: Encodable<S, E> -//! > Encodable<S, E> for Spanned<T> { -//! fn encode(&self, s: &mut S) -> Result<(), E> { -//! s.emit_struct("Spanned", 2, |this| { -//! this.emit_struct_field("node", 0, |this| self.node.encode(this)) -//! .unwrap(); -//! this.emit_struct_field("span", 1, |this| self.span.encode(this)) -//! }) -//! } -//! } -//! -//! impl< -//! D: Decoder<E>, -//! E, -//! T: Decodable<D, E> -//! > Decodable<D, E> for Spanned<T> { -//! fn decode(d: &mut D) -> Result<Spanned<T>, E> { -//! d.read_struct("Spanned", 2, |this| { -//! Ok(Spanned { -//! node: this.read_struct_field("node", 0, |this| Decodable::decode(this)) -//! .unwrap(), -//! span: this.read_struct_field("span", 1, |this| Decodable::decode(this)) -//! .unwrap(), -//! }) -//! }) -//! } -//! } -//! ``` - -use rustc_ast::{AttrVec, ExprKind, MetaItem, Mutability}; -use rustc_expand::base::{Annotatable, ExtCtxt}; -use rustc_span::{Ident, Span, Symbol, sym}; -use thin_vec::{ThinVec, thin_vec}; - -use crate::deriving::generic::ty::*; -use crate::deriving::generic::*; -use crate::deriving::pathvec_std; - -pub(crate) fn expand_deriving_rustc_encodable( - cx: &ExtCtxt<'_>, - span: Span, - mitem: &MetaItem, - item: &Annotatable, - push: &mut dyn FnMut(Annotatable), - is_const: bool, -) { - let krate = sym::rustc_serialize; - let typaram = sym::__S; - - let trait_def = TraitDef { - span, - path: Path::new_(vec![krate, sym::Encodable], vec![], PathKind::Global), - skip_path_as_bound: false, - needs_copy_as_bound_if_packed: true, - additional_bounds: Vec::new(), - supports_unions: false, - methods: vec![MethodDef { - name: sym::encode, - generics: Bounds { - bounds: vec![(typaram, vec![Path::new_( - vec![krate, sym::Encoder], - vec![], - PathKind::Global, - )])], - }, - explicit_self: true, - nonself_args: vec![( - Ref(Box::new(Path(Path::new_local(typaram))), Mutability::Mut), - sym::s, - )], - ret_ty: Path(Path::new_( - pathvec_std!(result::Result), - vec![ - Box::new(Unit), - Box::new(Path(Path::new_(vec![typaram, sym::Error], vec![], PathKind::Local))), - ], - PathKind::Std, - )), - attributes: AttrVec::new(), - fieldless_variants_strategy: FieldlessVariantsStrategy::Default, - combine_substructure: combine_substructure(Box::new(|a, b, c| { - encodable_substructure(a, b, c, krate) - })), - }], - associated_types: Vec::new(), - is_const, - }; - - trait_def.expand(cx, mitem, item, push) -} - -fn encodable_substructure( - cx: &ExtCtxt<'_>, - trait_span: Span, - substr: &Substructure<'_>, - krate: Symbol, -) -> BlockOrExpr { - let encoder = substr.nonselflike_args[0].clone(); - // throw an underscore in front to suppress unused variable warnings - let blkarg = Ident::new(sym::_e, trait_span); - let blkencoder = cx.expr_ident(trait_span, blkarg); - let fn_path = cx.expr_path(cx.path_global(trait_span, vec![ - Ident::new(krate, trait_span), - Ident::new(sym::Encodable, trait_span), - Ident::new(sym::encode, trait_span), - ])); - - match substr.fields { - Struct(_, fields) => { - let fn_emit_struct_field_path = - cx.def_site_path(&[sym::rustc_serialize, sym::Encoder, sym::emit_struct_field]); - let mut stmts = ThinVec::new(); - for (i, &FieldInfo { name, ref self_expr, span, .. }) in fields.iter().enumerate() { - let name = match name { - Some(id) => id.name, - None => Symbol::intern(&format!("_field{i}")), - }; - let self_ref = cx.expr_addr_of(span, self_expr.clone()); - let enc = - cx.expr_call(span, fn_path.clone(), thin_vec![self_ref, blkencoder.clone()]); - let lambda = cx.lambda1(span, enc, blkarg); - let call = cx.expr_call_global(span, fn_emit_struct_field_path.clone(), thin_vec![ - blkencoder.clone(), - cx.expr_str(span, name), - cx.expr_usize(span, i), - lambda, - ]); - - // last call doesn't need a try! - let last = fields.len() - 1; - let call = if i != last { - cx.expr_try(span, call) - } else { - cx.expr(span, ExprKind::Ret(Some(call))) - }; - - let stmt = cx.stmt_expr(call); - stmts.push(stmt); - } - - // unit structs have no fields and need to return Ok() - let blk = if stmts.is_empty() { - let ok = cx.expr_ok(trait_span, cx.expr_tuple(trait_span, ThinVec::new())); - cx.lambda1(trait_span, ok, blkarg) - } else { - cx.lambda_stmts_1(trait_span, stmts, blkarg) - }; - - let fn_emit_struct_path = - cx.def_site_path(&[sym::rustc_serialize, sym::Encoder, sym::emit_struct]); - - let expr = cx.expr_call_global(trait_span, fn_emit_struct_path, thin_vec![ - encoder, - cx.expr_str(trait_span, substr.type_ident.name), - cx.expr_usize(trait_span, fields.len()), - blk, - ]); - BlockOrExpr::new_expr(expr) - } - - EnumMatching(idx, variant, fields) => { - // We're not generating an AST that the borrow checker is expecting, - // so we need to generate a unique local variable to take the - // mutable loan out on, otherwise we get conflicts which don't - // actually exist. - let me = cx.stmt_let(trait_span, false, blkarg, encoder); - let encoder = cx.expr_ident(trait_span, blkarg); - - let fn_emit_enum_variant_arg_path: Vec<_> = - cx.def_site_path(&[sym::rustc_serialize, sym::Encoder, sym::emit_enum_variant_arg]); - - let mut stmts = ThinVec::new(); - if !fields.is_empty() { - let last = fields.len() - 1; - for (i, &FieldInfo { ref self_expr, span, .. }) in fields.iter().enumerate() { - let self_ref = cx.expr_addr_of(span, self_expr.clone()); - let enc = cx - .expr_call(span, fn_path.clone(), thin_vec![self_ref, blkencoder.clone()]); - let lambda = cx.lambda1(span, enc, blkarg); - - let call = cx.expr_call_global( - span, - fn_emit_enum_variant_arg_path.clone(), - thin_vec![blkencoder.clone(), cx.expr_usize(span, i), lambda], - ); - let call = if i != last { - cx.expr_try(span, call) - } else { - cx.expr(span, ExprKind::Ret(Some(call))) - }; - stmts.push(cx.stmt_expr(call)); - } - } else { - let ok = cx.expr_ok(trait_span, cx.expr_tuple(trait_span, ThinVec::new())); - let ret_ok = cx.expr(trait_span, ExprKind::Ret(Some(ok))); - stmts.push(cx.stmt_expr(ret_ok)); - } - - let blk = cx.lambda_stmts_1(trait_span, stmts, blkarg); - let name = cx.expr_str(trait_span, variant.ident.name); - - let fn_emit_enum_variant_path: Vec<_> = - cx.def_site_path(&[sym::rustc_serialize, sym::Encoder, sym::emit_enum_variant]); - - let call = cx.expr_call_global(trait_span, fn_emit_enum_variant_path, thin_vec![ - blkencoder, - name, - cx.expr_usize(trait_span, *idx), - cx.expr_usize(trait_span, fields.len()), - blk, - ]); - - let blk = cx.lambda1(trait_span, call, blkarg); - let fn_emit_enum_path: Vec<_> = - cx.def_site_path(&[sym::rustc_serialize, sym::Encoder, sym::emit_enum]); - let expr = cx.expr_call_global(trait_span, fn_emit_enum_path, thin_vec![ - encoder, - cx.expr_str(trait_span, substr.type_ident.name), - blk - ]); - BlockOrExpr::new_mixed(thin_vec![me], Some(expr)) - } - - _ => cx.dcx().bug("expected Struct or EnumMatching in derive(Encodable)"), - } -} |