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// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use ast;
use ast::{MetaItem, item, Expr};
use codemap::Span;
use ext::base::ExtCtxt;
use ext::build::AstBuilder;
use ext::deriving::generic::*;
pub fn expand_deriving_ord(cx: @ExtCtxt,
span: Span,
mitem: @MetaItem,
in_items: ~[@item]) -> ~[@item] {
macro_rules! md (
($name:expr, $op:expr, $equal:expr) => {
MethodDef {
name: $name,
generics: LifetimeBounds::empty(),
explicit_self: borrowed_explicit_self(),
args: ~[borrowed_self()],
ret_ty: Literal(Path::new(~["bool"])),
const_nonmatching: false,
combine_substructure: |cx, span, substr| cs_op($op, $equal, cx, span, substr)
}
}
);
let trait_def = TraitDef {
path: Path::new(~["std", "cmp", "Ord"]),
additional_bounds: ~[],
generics: LifetimeBounds::empty(),
methods: ~[
md!("lt", true, false),
md!("le", true, true),
md!("gt", false, false),
md!("ge", false, true)
]
};
trait_def.expand(cx, span, mitem, in_items)
}
/// Strict inequality.
fn cs_op(less: bool, equal: bool, cx: @ExtCtxt, span: Span, substr: &Substructure) -> @Expr {
let op = if less {ast::BiLt} else {ast::BiGt};
cs_fold(
false, // need foldr,
|cx, span, subexpr, self_f, other_fs| {
/*
build up a series of chain ||'s and &&'s from the inside
out (hence foldr) to get lexical ordering, i.e. for op ==
`ast::lt`
```
self.f1 < other.f1 || (!(other.f1 < self.f1) &&
(self.f2 < other.f2 || (!(other.f2 < self.f2) &&
(false)
))
)
```
The optimiser should remove the redundancy. We explicitly
get use the binops to avoid auto-deref derefencing too many
layers of pointers, if the type includes pointers.
*/
let other_f = match other_fs {
[o_f] => o_f,
_ => cx.span_bug(span, "Not exactly 2 arguments in `deriving(Ord)`")
};
let cmp = cx.expr_binary(span, op,
cx.expr_deref(span, self_f),
cx.expr_deref(span, other_f));
let not_cmp = cx.expr_unary(span, ast::UnNot,
cx.expr_binary(span, op,
cx.expr_deref(span, other_f),
cx.expr_deref(span, self_f)));
let and = cx.expr_binary(span, ast::BiAnd, not_cmp, subexpr);
cx.expr_binary(span, ast::BiOr, cmp, and)
},
cx.expr_bool(span, equal),
|cx, span, args, _| {
// nonmatching enums, order by the order the variants are
// written
match args {
[(self_var, _, _),
(other_var, _, _)] =>
cx.expr_bool(span,
if less {
self_var < other_var
} else {
self_var > other_var
}),
_ => cx.span_bug(span, "Not exactly 2 arguments in `deriving(Ord)`")
}
},
cx, span, substr)
}
|
