1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use ast::{MetaItem, Item, Expr, MutMutable};
13 use ext::base::ExtCtxt;
14 use ext::build::AstBuilder;
15 use ext::deriving::generic::*;
16 use ext::deriving::generic::ty::*;
19 pub fn expand_deriving_hash<F>(cx: &mut ExtCtxt,
27 let path = Path::new_(pathvec_std!(cx, core::hash::Hash), None,
29 let arg = Path::new_local("__H");
30 let hash_trait_def = TraitDef {
32 attributes: Vec::new(),
34 additional_bounds: Vec::new(),
35 generics: LifetimeBounds::empty(),
39 generics: LifetimeBounds {
40 lifetimes: Vec::new(),
42 vec![path_std!(cx, core::hash::Hasher)])],
44 explicit_self: borrowed_explicit_self(),
45 args: vec!(Ptr(box Literal(arg), Borrowed(None, MutMutable))),
48 combine_substructure: combine_substructure(box |a, b, c| {
49 hash_substructure(a, b, c)
53 associated_types: Vec::new(),
56 hash_trait_def.expand(cx, mitem, item, push);
59 fn hash_substructure(cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure) -> P<Expr> {
60 let state_expr = match substr.nonself_args {
61 [ref state_expr] => state_expr,
62 _ => cx.span_bug(trait_span, "incorrect number of arguments in `derive(Hash)`")
64 let call_hash = |span, thing_expr| {
67 cx.ident_of_std("core"),
73 cx.expr_path(cx.path_global(span, strs))
75 let ref_thing = cx.expr_addr_of(span, thing_expr);
76 let expr = cx.expr_call(span, hash_path, vec!(ref_thing, state_expr.clone()));
79 let mut stmts = Vec::new();
81 let fields = match *substr.fields {
83 EnumMatching(index, variant, ref fs) => {
84 // Determine the discriminant. We will feed this value to the byte
85 // iteration function.
86 let discriminant = match variant.node.disr_expr {
87 Some(ref d) => d.clone(),
88 None => cx.expr_usize(trait_span, index)
91 stmts.push(call_hash(trait_span, discriminant));
95 _ => cx.span_bug(trait_span, "impossible substructure in `derive(Hash)`")
98 for &FieldInfo { ref self_, span, .. } in fields {
99 stmts.push(call_hash(span, self_.clone()));
102 cx.expr_block(cx.block(trait_span, stmts, None))