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.
12 use ast::{MetaItem, Item, Expr, MutMutable};
14 use ext::base::ExtCtxt;
15 use ext::build::AstBuilder;
16 use ext::deriving::generic::*;
18 pub fn expand_deriving_hash(cx: &mut ExtCtxt,
24 let (path, generics, args) = if cx.ecfg.deriving_hash_type_parameter {
25 (Path::new_(vec!("std", "hash", "Hash"), None,
26 vec!(~Literal(Path::new_local("__S"))), true),
28 lifetimes: Vec::new(),
29 bounds: vec!(("__S", ast::StaticSize, vec!(Path::new(vec!("std", "io", "Writer"))))),
31 Path::new_local("__S"))
33 (Path::new(vec!("std", "hash", "Hash")),
34 LifetimeBounds::empty(),
35 Path::new(vec!("std", "hash", "sip", "SipState")))
37 let hash_trait_def = TraitDef {
39 attributes: Vec::new(),
41 additional_bounds: Vec::new(),
46 generics: LifetimeBounds::empty(),
47 explicit_self: borrowed_explicit_self(),
48 args: vec!(Ptr(~Literal(args), Borrowed(None, MutMutable))),
51 const_nonmatching: false,
52 combine_substructure: hash_substructure
57 hash_trait_def.expand(cx, mitem, item, push);
60 fn hash_substructure(cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure) -> @Expr {
61 let state_expr = match substr.nonself_args {
62 [state_expr] => state_expr,
63 _ => cx.span_bug(trait_span, "incorrect number of arguments in `deriving(Hash)`")
65 let hash_ident = substr.method_ident;
66 let call_hash = |span, thing_expr| {
67 let expr = cx.expr_method_call(span, thing_expr, hash_ident, vec!(state_expr));
70 let mut stmts = Vec::new();
72 let fields = match *substr.fields {
74 EnumMatching(index, variant, ref fs) => {
75 // Determine the discriminant. We will feed this value to the byte
76 // iteration function.
77 let discriminant = match variant.node.disr_expr {
79 None => cx.expr_uint(trait_span, index)
82 stmts.push(call_hash(trait_span, discriminant));
86 _ => cx.span_bug(trait_span, "impossible substructure in `deriving(Hash)`")
89 for &FieldInfo { self_, span, .. } in fields.iter() {
90 stmts.push(call_hash(span, self_));
94 cx.span_bug(trait_span, "#[deriving(Hash)] needs at least one field");
97 cx.expr_block(cx.block(trait_span, stmts, None))