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// Copyright 2014 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::{MetaItem, Item, Expr, MutMutable};
use codemap::Span;
use ext::base::ExtCtxt;
use ext::build::AstBuilder;
use ext::deriving::generic::*;
use ext::deriving::generic::ty::*;
use parse::token::InternedString;
use ptr::P;
pub fn expand_deriving_hash<F>(cx: &mut ExtCtxt,
span: Span,
mitem: &MetaItem,
item: &Item,
push: F) where
F: FnOnce(P<Item>),
{
let path = Path::new_(vec!("std", "hash", "Hash"), None,
vec!(box Literal(Path::new_local("__S"))), true);
let generics = LifetimeBounds {
lifetimes: Vec::new(),
bounds: vec!(("__S",
vec!(Path::new(vec!("std", "hash", "Writer")),
Path::new(vec!("std", "hash", "Hasher"))))),
};
let args = Path::new_local("__S");
let inline = cx.meta_word(span, InternedString::new("inline"));
let attrs = vec!(cx.attribute(span, inline));
let hash_trait_def = TraitDef {
span: span,
attributes: Vec::new(),
path: path,
additional_bounds: Vec::new(),
generics: generics,
methods: vec!(
MethodDef {
name: "hash",
generics: LifetimeBounds::empty(),
explicit_self: borrowed_explicit_self(),
args: vec!(Ptr(box Literal(args), Borrowed(None, MutMutable))),
ret_ty: nil_ty(),
attributes: attrs,
combine_substructure: combine_substructure(box |a, b, c| {
hash_substructure(a, b, c)
})
}
)
};
hash_trait_def.expand(cx, mitem, item, push);
}
fn hash_substructure(cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure) -> P<Expr> {
let state_expr = match substr.nonself_args {
[ref state_expr] => state_expr,
_ => cx.span_bug(trait_span, "incorrect number of arguments in `deriving(Hash)`")
};
let hash_ident = substr.method_ident;
let call_hash = |&: span, thing_expr| {
let expr = cx.expr_method_call(span, thing_expr, hash_ident, vec!(state_expr.clone()));
cx.stmt_expr(expr)
};
let mut stmts = Vec::new();
let fields = match *substr.fields {
Struct(ref fs) => fs,
EnumMatching(index, variant, ref fs) => {
// Determine the discriminant. We will feed this value to the byte
// iteration function.
let discriminant = match variant.node.disr_expr {
Some(ref d) => d.clone(),
None => cx.expr_uint(trait_span, index)
};
stmts.push(call_hash(trait_span, discriminant));
fs
}
_ => cx.span_bug(trait_span, "impossible substructure in `deriving(Hash)`")
};
for &FieldInfo { ref self_, span, .. } in fields.iter() {
stmts.push(call_hash(span, self_.clone()));
}
if stmts.len() == 0 {
cx.span_bug(trait_span, "#[derive(Hash)] needs at least one field");
}
cx.expr_block(cx.block(trait_span, stmts, None))
}
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