118 lines
4.1 KiB
Rust
118 lines
4.1 KiB
Rust
use crate::deriving::path_std;
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use crate::deriving::generic::*;
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use crate::deriving::generic::ty::*;
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use syntax::ast::{self, Expr, MetaItem};
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use syntax::ext::base::{Annotatable, ExtCtxt};
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use syntax::ptr::P;
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use syntax::symbol::sym;
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use syntax_pos::Span;
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pub fn expand_deriving_ord(cx: &mut ExtCtxt<'_>,
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span: Span,
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mitem: &MetaItem,
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item: &Annotatable,
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push: &mut dyn FnMut(Annotatable)) {
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let inline = cx.meta_word(span, sym::inline);
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let attrs = vec![cx.attribute(inline)];
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let trait_def = TraitDef {
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span,
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attributes: Vec::new(),
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path: path_std!(cx, cmp::Ord),
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additional_bounds: Vec::new(),
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generics: LifetimeBounds::empty(),
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is_unsafe: false,
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supports_unions: false,
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methods: vec![MethodDef {
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name: "cmp",
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generics: LifetimeBounds::empty(),
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explicit_self: borrowed_explicit_self(),
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args: vec![(borrowed_self(), "other")],
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ret_ty: Literal(path_std!(cx, cmp::Ordering)),
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attributes: attrs,
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is_unsafe: false,
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unify_fieldless_variants: true,
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combine_substructure: combine_substructure(Box::new(|a, b, c| {
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cs_cmp(a, b, c)
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})),
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}],
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associated_types: Vec::new(),
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};
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trait_def.expand(cx, mitem, item, push)
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}
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pub fn ordering_collapsed(
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cx: &mut ExtCtxt<'_>,
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span: Span,
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self_arg_tags: &[ast::Ident],
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) -> P<ast::Expr> {
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let lft = cx.expr_ident(span, self_arg_tags[0]);
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let rgt = cx.expr_addr_of(span, cx.expr_ident(span, self_arg_tags[1]));
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cx.expr_method_call(span, lft, ast::Ident::new(sym::cmp, span), vec![rgt])
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}
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pub fn cs_cmp(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>) -> P<Expr> {
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let test_id = ast::Ident::new(sym::cmp, span);
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let equals_path = cx.path_global(span, cx.std_path(&[sym::cmp, sym::Ordering, sym::Equal]));
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let cmp_path = cx.std_path(&[sym::cmp, sym::Ord, sym::cmp]);
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// Builds:
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//
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// match ::std::cmp::Ord::cmp(&self_field1, &other_field1) {
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// ::std::cmp::Ordering::Equal =>
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// match ::std::cmp::Ord::cmp(&self_field2, &other_field2) {
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// ::std::cmp::Ordering::Equal => {
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// ...
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// }
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// cmp => cmp
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// },
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// cmp => cmp
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// }
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//
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cs_fold(// foldr nests the if-elses correctly, leaving the first field
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// as the outermost one, and the last as the innermost.
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false,
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|cx, span, old, self_f, other_fs| {
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// match new {
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// ::std::cmp::Ordering::Equal => old,
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// cmp => cmp
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// }
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let new = {
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let other_f = match other_fs {
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[o_f] => o_f,
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_ => cx.span_bug(span, "not exactly 2 arguments in `derive(Ord)`"),
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};
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let args = vec![
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cx.expr_addr_of(span, self_f),
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cx.expr_addr_of(span, other_f.clone()),
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];
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cx.expr_call_global(span, cmp_path.clone(), args)
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};
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let eq_arm = cx.arm(span,
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vec![cx.pat_path(span, equals_path.clone())],
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old);
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let neq_arm = cx.arm(span,
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vec![cx.pat_ident(span, test_id)],
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cx.expr_ident(span, test_id));
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cx.expr_match(span, new, vec![eq_arm, neq_arm])
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},
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cx.expr_path(equals_path.clone()),
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Box::new(|cx, span, (self_args, tag_tuple), _non_self_args| {
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if self_args.len() != 2 {
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cx.span_bug(span, "not exactly 2 arguments in `derive(Ord)`")
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} else {
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ordering_collapsed(cx, span, tag_tuple)
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}
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}),
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cx,
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span,
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substr)
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}
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