totaleq.rs

// Copyright 2013 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};
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 std::gc::Gc;

pub fn expand_deriving_totaleq(cx: &mut ExtCtxt,
                               span: Span,
                               mitem: Gc<MetaItem>,
                               item: Gc<Item>,
                               push: |Gc<Item>|) {
    fn cs_total_eq_assert(cx: &mut ExtCtxt, span: Span,
                          substr: &Substructure) -> Gc<Expr> {
        cs_same_method(|cx, span, exprs| {
            // create `a.<method>(); b.<method>(); c.<method>(); ...`
            // (where method is `assert_receiver_is_total_eq`)
            let stmts = exprs.move_iter().map(|e| cx.stmt_expr(e)).collect();
            let block = cx.block(span, stmts, None);
            cx.expr_block(block)
        },
                       |cx, sp, _, _| cx.span_bug(sp, "non matching enums in deriving(Eq)?"),
                       cx,
                       span,
                       substr)
    }

    let inline = cx.meta_word(span, InternedString::new("inline"));
    let hidden = cx.meta_word(span, InternedString::new("hidden"));
    let doc = cx.meta_list(span, InternedString::new("doc"), vec!(hidden));
    let attrs = vec!(cx.attribute(span, inline),
                     cx.attribute(span, doc));
    let trait_def = TraitDef {
        span: span,
        attributes: Vec::new(),
        path: Path::new(vec!("std", "cmp", "Eq")),
        additional_bounds: Vec::new(),
        generics: LifetimeBounds::empty(),
        methods: vec!(
            MethodDef {
                name: "assert_receiver_is_total_eq",
                generics: LifetimeBounds::empty(),
                explicit_self: borrowed_explicit_self(),
                args: vec!(),
                ret_ty: nil_ty(),
                attributes: attrs,
                on_nonmatching: NonMatchesCollapse,
                combine_substructure: combine_substructure(|a, b, c| {
                    cs_total_eq_assert(a, b, c)
                })
            }
        )
    };
    trait_def.expand(cx, mitem, item, push)
}