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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::{meta_item, item, expr};
use codemap::span;
use ext::base::ExtCtxt;
use ext::build::AstBuilder;
use ext::deriving::generic::*;
use std::cmp::{Ordering, Equal, Less, Greater};
pub fn expand_deriving_totalord(cx: @ExtCtxt,
span: span,
mitem: @meta_item,
in_items: ~[@item]) -> ~[@item] {
let trait_def = TraitDef {
path: Path::new(~["std", "cmp", "TotalOrd"]),
additional_bounds: ~[],
generics: LifetimeBounds::empty(),
methods: ~[
MethodDef {
name: "cmp",
generics: LifetimeBounds::empty(),
explicit_self: borrowed_explicit_self(),
args: ~[borrowed_self()],
ret_ty: Literal(Path::new(~["std", "cmp", "Ordering"])),
const_nonmatching: false,
combine_substructure: cs_cmp
}
]
};
trait_def.expand(cx, span, mitem, in_items)
}
pub fn ordering_const(cx: @ExtCtxt, span: span, cnst: Ordering) -> @expr {
let cnst = match cnst {
Less => "Less",
Equal => "Equal",
Greater => "Greater"
};
cx.expr_path(
cx.path_global(span,
~[cx.ident_of("std"),
cx.ident_of("cmp"),
cx.ident_of(cnst)]))
}
pub fn cs_cmp(cx: @ExtCtxt, span: span,
substr: &Substructure) -> @expr {
cs_same_method_fold(
// foldr (possibly) nests the matches in lexical_ordering better
false,
|cx, span, old, new| {
cx.expr_call_global(span,
~[cx.ident_of("std"),
cx.ident_of("cmp"),
cx.ident_of("lexical_ordering")],
~[old, new])
},
ordering_const(cx, span, Equal),
|cx, span, list, _| {
match list {
// an earlier nonmatching variant is Less than a
// later one
[(self_var, _, _),
(other_var, _, _)] => ordering_const(cx, span,
self_var.cmp(&other_var)),
_ => cx.span_bug(span, "Not exactly 2 arguments in `deriving(TotalOrd)`")
}
},
cx, span, substr)
}
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