109 lines
3.8 KiB
Rust
109 lines
3.8 KiB
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use ast::{MetaItem, Item, Expr, MutMutable};
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use codemap::Span;
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use ext::base::ExtCtxt;
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use ext::build::AstBuilder;
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use ext::deriving::generic::*;
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use ext::deriving::generic::ty::*;
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use parse::token::InternedString;
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use ptr::P;
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pub fn expand_deriving_hash<F>(cx: &mut ExtCtxt,
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span: Span,
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mitem: &MetaItem,
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item: &Item,
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push: F) where
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F: FnOnce(P<Item>),
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{
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let path = Path::new_(vec!("std", "hash", "Hash"), None,
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vec!(box Literal(Path::new_local("__S"))), true);
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let generics = LifetimeBounds {
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lifetimes: Vec::new(),
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bounds: vec!(("__S",
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vec!(Path::new(vec!("std", "hash", "Writer")),
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Path::new(vec!("std", "hash", "Hasher"))))),
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};
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let args = Path::new_local("__S");
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let inline = cx.meta_word(span, InternedString::new("inline"));
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let attrs = vec!(cx.attribute(span, inline));
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let hash_trait_def = TraitDef {
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span: span,
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attributes: Vec::new(),
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path: path,
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additional_bounds: Vec::new(),
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generics: generics,
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methods: vec!(
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MethodDef {
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name: "hash",
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generics: LifetimeBounds::empty(),
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explicit_self: borrowed_explicit_self(),
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args: vec!(Ptr(box Literal(args), Borrowed(None, MutMutable))),
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ret_ty: nil_ty(),
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attributes: attrs,
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combine_substructure: combine_substructure(box |a, b, c| {
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hash_substructure(a, b, c)
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})
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}
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),
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associated_types: Vec::new(),
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};
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hash_trait_def.expand(cx, mitem, item, push);
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}
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fn hash_substructure(cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure) -> P<Expr> {
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let state_expr = match substr.nonself_args {
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[ref state_expr] => state_expr,
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_ => cx.span_bug(trait_span, "incorrect number of arguments in `derive(Hash)`")
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};
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let call_hash = |&: span, thing_expr| {
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let hash_path = {
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let strs = vec![
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cx.ident_of("std"),
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cx.ident_of("hash"),
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cx.ident_of("Hash"),
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cx.ident_of("hash"),
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];
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cx.expr_path(cx.path_global(span, strs))
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};
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let ref_thing = cx.expr_addr_of(span, thing_expr);
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let expr = cx.expr_call(span, hash_path, vec!(ref_thing, state_expr.clone()));
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cx.stmt_expr(expr)
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};
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let mut stmts = Vec::new();
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let fields = match *substr.fields {
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Struct(ref fs) => fs,
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EnumMatching(index, variant, ref fs) => {
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// Determine the discriminant. We will feed this value to the byte
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// iteration function.
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let discriminant = match variant.node.disr_expr {
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Some(ref d) => d.clone(),
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None => cx.expr_usize(trait_span, index)
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};
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stmts.push(call_hash(trait_span, discriminant));
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fs
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}
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_ => cx.span_bug(trait_span, "impossible substructure in `derive(Hash)`")
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};
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for &FieldInfo { ref self_, span, .. } in fields.iter() {
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stmts.push(call_hash(span, self_.clone()));
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}
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cx.expr_block(cx.block(trait_span, stmts, None))
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}
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