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Diffstat (limited to '')
-rw-r--r-- | compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs new file mode 100644 index 000000000..1612be862 --- /dev/null +++ b/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs @@ -0,0 +1,79 @@ +use crate::deriving::generic::ty::*; +use crate::deriving::generic::*; +use crate::deriving::path_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_ord( + cx: &mut ExtCtxt<'_>, + span: Span, + mitem: &MetaItem, + item: &Annotatable, + push: &mut dyn FnMut(Annotatable), +) { + let inline = cx.meta_word(span, sym::inline); + let attrs = vec![cx.attribute(inline)]; + let trait_def = TraitDef { + span, + attributes: Vec::new(), + path: path_std!(cmp::Ord), + additional_bounds: Vec::new(), + generics: Bounds::empty(), + supports_unions: false, + methods: vec![MethodDef { + name: sym::cmp, + generics: Bounds::empty(), + explicit_self: true, + nonself_args: vec![(self_ref(), sym::other)], + ret_ty: Path(path_std!(cmp::Ordering)), + attributes: attrs, + unify_fieldless_variants: true, + combine_substructure: combine_substructure(Box::new(|a, b, c| cs_cmp(a, b, c))), + }], + associated_types: Vec::new(), + }; + + trait_def.expand(cx, mitem, item, push) +} + +pub fn cs_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 cmp_path = cx.std_path(&[sym::cmp, sym::Ord, sym::cmp]); + + // Builds: + // + // match ::core::cmp::Ord::cmp(&self.x, &other.x) { + // ::std::cmp::Ordering::Equal => + // ::core::cmp::Ord::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, cmp_path.clone(), args) + } + CsFold::Combine(span, expr1, expr2) => { + let eq_arm = cx.arm(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_path(equal_path.clone()), + }, + ); + BlockOrExpr::new_expr(expr) +} |