diff options
Diffstat (limited to 'compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs')
-rw-r--r-- | compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs new file mode 100644 index 000000000..2ebb01cc8 --- /dev/null +++ b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs @@ -0,0 +1,88 @@ +use crate::deriving::generic::ty::*; +use crate::deriving::generic::*; +use crate::deriving::{path_std, pathvec_std}; + +use rustc_ast::MetaItem; +use rustc_expand::base::{Annotatable, ExtCtxt}; +use rustc_span::symbol::{sym, Ident}; +use rustc_span::Span; + +pub fn expand_deriving_partial_ord( + cx: &mut ExtCtxt<'_>, + span: Span, + mitem: &MetaItem, + item: &Annotatable, + push: &mut dyn FnMut(Annotatable), +) { + let ordering_ty = Path(path_std!(cmp::Ordering)); + let ret_ty = + Path(Path::new_(pathvec_std!(option::Option), vec![Box::new(ordering_ty)], PathKind::Std)); + + let inline = cx.meta_word(span, sym::inline); + let attrs = vec![cx.attribute(inline)]; + + let partial_cmp_def = MethodDef { + name: sym::partial_cmp, + generics: Bounds::empty(), + explicit_self: true, + nonself_args: vec![(self_ref(), sym::other)], + ret_ty, + attributes: attrs, + unify_fieldless_variants: true, + combine_substructure: combine_substructure(Box::new(|cx, span, substr| { + cs_partial_cmp(cx, span, substr) + })), + }; + + let trait_def = TraitDef { + span, + attributes: vec![], + path: path_std!(cmp::PartialOrd), + additional_bounds: vec![], + generics: Bounds::empty(), + supports_unions: false, + methods: vec![partial_cmp_def], + associated_types: Vec::new(), + }; + trait_def.expand(cx, mitem, item, push) +} + +pub fn cs_partial_cmp(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>) -> BlockOrExpr { + let test_id = Ident::new(sym::cmp, span); + let equal_path = cx.path_global(span, cx.std_path(&[sym::cmp, sym::Ordering, sym::Equal])); + let partial_cmp_path = cx.std_path(&[sym::cmp, sym::PartialOrd, sym::partial_cmp]); + + // Builds: + // + // match ::core::cmp::PartialOrd::partial_cmp(&self.x, &other.x) { + // ::core::option::Option::Some(::core::cmp::Ordering::Equal) => + // ::core::cmp::PartialOrd::partial_cmp(&self.y, &other.y), + // cmp => cmp, + // } + let expr = cs_fold( + // foldr nests the if-elses correctly, leaving the first field + // as the outermost one, and the last as the innermost. + false, + cx, + span, + substr, + |cx, fold| match fold { + CsFold::Single(field) => { + let [other_expr] = &field.other_selflike_exprs[..] else { + cx.span_bug(field.span, "not exactly 2 arguments in `derive(Ord)`"); + }; + let args = vec![field.self_expr.clone(), other_expr.clone()]; + cx.expr_call_global(field.span, partial_cmp_path.clone(), args) + } + CsFold::Combine(span, expr1, expr2) => { + let eq_arm = + cx.arm(span, cx.pat_some(span, cx.pat_path(span, equal_path.clone())), expr1); + let neq_arm = + cx.arm(span, cx.pat_ident(span, test_id), cx.expr_ident(span, test_id)); + cx.expr_match(span, expr2, vec![eq_arm, neq_arm]) + } + CsFold::Fieldless => cx.expr_some(span, cx.expr_path(equal_path.clone())), + }, + ); + BlockOrExpr::new_expr(expr) +} |