}
}
-fn variant_to_pat(cx: &mut ExtCtxt, sp: Span, enum_ident: ast::Ident, variant: &ast::Variant)
- -> P<ast::Pat> {
- let path = cx.path(sp, vec![enum_ident, variant.node.name]);
- cx.pat(sp, match variant.node.kind {
- ast::TupleVariantKind(..) => ast::PatEnum(path, None),
- ast::StructVariantKind(..) => ast::PatStruct(path, Vec::new(), true),
- })
-}
-
impl<'a> MethodDef<'a> {
fn call_substructure_method(&self,
cx: &mut ExtCtxt,
.collect::<Vec<ast::Ident>>();
// The `vi_idents` will be bound, solely in the catch-all, to
- // a series of let statements mapping each self_arg to a usize
- // corresponding to its variant index.
+ // a series of let statements mapping each self_arg to an isize
+ // corresponding to its discriminant value.
let vi_idents: Vec<ast::Ident> = self_arg_names.iter()
.map(|name| { let vi_suffix = format!("{}_vi", &name[..]);
cx.ident_of(&vi_suffix[..]) })
// unreachable-pattern error.
//
if variants.len() > 1 && self_args.len() > 1 {
- let arms: Vec<ast::Arm> = variants.iter().enumerate()
- .map(|(index, variant)| {
- let pat = variant_to_pat(cx, sp, type_ident, &**variant);
- let lit = ast::LitInt(index as u64, ast::UnsignedIntLit(ast::TyUs));
- cx.arm(sp, vec![pat], cx.expr_lit(sp, lit))
- }).collect();
-
// Build a series of let statements mapping each self_arg
- // to a usize corresponding to its variant index.
+ // to its discriminant value. If this is a C-style enum
+ // with a specific repr type, then casts the values to
+ // that type. Otherwise casts to `isize`.
+ //
// i.e. for `enum E<T> { A, B(1), C(T, T) }`, and a deriving
// with three Self args, builds three statements:
//
// ```
- // let __self0_vi = match self {
- // A => 0, B(..) => 1, C(..) => 2
- // };
- // let __self1_vi = match __arg1 {
- // A => 0, B(..) => 1, C(..) => 2
- // };
- // let __self2_vi = match __arg2 {
- // A => 0, B(..) => 1, C(..) => 2
- // };
+ // let __self0_vi = unsafe {
+ // std::intrinsics::discriminant_value(&self) } as isize;
+ // let __self1_vi = unsafe {
+ // std::intrinsics::discriminant_value(&__arg1) } as isize;
+ // let __self2_vi = unsafe {
+ // std::intrinsics::discriminant_value(&__arg2) } as isize;
// ```
let mut index_let_stmts: Vec<P<ast::Stmt>> = Vec::new();
for (&ident, self_arg) in vi_idents.iter().zip(self_args.iter()) {
- let variant_idx = cx.expr_match(sp, self_arg.clone(), arms.clone());
- let let_stmt = cx.stmt_let(sp, false, ident, variant_idx);
+ let path = vec![cx.ident_of_std("core"),
+ cx.ident_of("intrinsics"),
+ cx.ident_of("discriminant_value")];
+ let call = cx.expr_call_global(
+ sp, path, vec![cx.expr_addr_of(sp, self_arg.clone())]);
+ let variant_value = cx.expr_block(P(ast::Block {
+ stmts: vec![],
+ expr: Some(call),
+ id: ast::DUMMY_NODE_ID,
+ rules: ast::UnsafeBlock(ast::CompilerGenerated),
+ span: sp }));
+
+ let target_ty = cx.ty_ident(sp, cx.ident_of("isize"));
+ let variant_disr = cx.expr_cast(sp, variant_value, target_ty);
+ let let_stmt = cx.stmt_let(sp, false, ident, variant_disr);
index_let_stmts.push(let_stmt);
}