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use deriving::{path_local, path_std};
use deriving::generic::*;
use deriving::generic::ty::*;
use syntax::ast::{BinOpKind, Expr, MetaItem};
use syntax::ext::base::{Annotatable, ExtCtxt};
use syntax::ext::build::AstBuilder;
use syntax::ptr::P;
use syntax::symbol::Symbol;
use syntax_pos::Span;
pub fn expand_deriving_partial_eq(cx: &mut ExtCtxt,
span: Span,
mitem: &MetaItem,
item: &Annotatable,
push: &mut FnMut(Annotatable)) {
fn cs_op(cx: &mut ExtCtxt,
span: Span,
substr: &Substructure,
op: BinOpKind,
combiner: BinOpKind,
base: bool)
-> P<Expr>
{
let op = |cx: &mut ExtCtxt, span: Span, self_f: P<Expr>, other_fs: &[P<Expr>]| {
let other_f = match (other_fs.len(), other_fs.get(0)) {
(1, Some(o_f)) => o_f,
_ => cx.span_bug(span, "not exactly 2 arguments in `derive(PartialEq)`"),
};
cx.expr_binary(span, op, self_f, other_f.clone())
};
cs_fold1(true,
|cx, span, subexpr, self_f, other_fs| {
let eq = op(cx, span, self_f, other_fs);
cx.expr_binary(span, combiner, subexpr, eq)
},
|cx, args| {
match args {
Some((span, self_f, other_fs)) => {
op(cx, span, self_f, other_fs)
}
None => cx.expr_bool(span, base),
}
},
Box::new(|cx, span, _, _| cx.expr_bool(span, !base)),
cx,
span,
substr)
}
fn cs_eq(cx: &mut ExtCtxt, span: Span, substr: &Substructure) -> P<Expr> {
cs_op(cx, span, substr, BinOpKind::Eq, BinOpKind::And, true)
}
fn cs_ne(cx: &mut ExtCtxt, span: Span, substr: &Substructure) -> P<Expr> {
cs_op(cx, span, substr, BinOpKind::Ne, BinOpKind::Or, false)
}
macro_rules! md {
($name:expr, $f:ident) => { {
let inline = cx.meta_word(span, Symbol::intern("inline"));
let attrs = vec![cx.attribute(span, inline)];
MethodDef {
name: $name,
generics: LifetimeBounds::empty(),
explicit_self: borrowed_explicit_self(),
args: vec![(borrowed_self(), "other")],
ret_ty: Literal(path_local!(bool)),
attributes: attrs,
is_unsafe: false,
unify_fieldless_variants: true,
combine_substructure: combine_substructure(Box::new(|a, b, c| {
$f(a, b, c)
}))
}
} }
}
let mut methods = vec![md!("eq", cs_eq)];
if !is_type_without_fields(item) {
methods.push(md!("ne", cs_ne));
}
let trait_def = TraitDef {
span,
attributes: Vec::new(),
path: path_std!(cx, cmp::PartialEq),
additional_bounds: Vec::new(),
generics: LifetimeBounds::empty(),
is_unsafe: false,
supports_unions: false,
methods,
associated_types: Vec::new(),
};
trait_def.expand(cx, mitem, item, push)
}