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// Copyright 2015 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.
// force-host
#![feature(plugin_registrar)]
#![feature(box_syntax)]
#![feature(rustc_private)]
extern crate syntax;
extern crate rustc;
extern crate rustc_plugin;
use syntax::ast;
use syntax::attr::AttrMetaMethods;
use syntax::codemap::Span;
use syntax::ext::base::{MultiDecorator, ExtCtxt, Annotatable};
use syntax::ext::build::AstBuilder;
use syntax::ext::deriving::generic::{cs_fold, TraitDef, MethodDef, combine_substructure};
use syntax::ext::deriving::generic::{Substructure, Struct, EnumMatching};
use syntax::ext::deriving::generic::ty::{Literal, LifetimeBounds, Path, borrowed_explicit_self};
use syntax::parse::token;
use syntax::ptr::P;
use rustc_plugin::Registry;
#[plugin_registrar]
pub fn plugin_registrar(reg: &mut Registry) {
reg.register_syntax_extension(
token::intern("derive_TotalSum"),
MultiDecorator(box expand));
}
fn expand(cx: &mut ExtCtxt,
span: Span,
mitem: &ast::MetaItem,
item: &Annotatable,
push: &mut FnMut(Annotatable)) {
let trait_def = TraitDef {
span: span,
attributes: vec![],
path: Path::new(vec!["TotalSum"]),
additional_bounds: vec![],
generics: LifetimeBounds::empty(),
associated_types: vec![],
is_unsafe: false,
methods: vec![
MethodDef {
name: "total_sum",
generics: LifetimeBounds::empty(),
explicit_self: borrowed_explicit_self(),
args: vec![],
ret_ty: Literal(Path::new_local("isize")),
attributes: vec![],
is_unsafe: false,
combine_substructure: combine_substructure(Box::new(totalsum_substructure)),
},
],
};
trait_def.expand(cx, mitem, item, push)
}
// Mostly copied from syntax::ext::deriving::hash
/// Defines how the implementation for `trace()` is to be generated
fn totalsum_substructure(cx: &mut ExtCtxt, trait_span: Span,
substr: &Substructure) -> P<ast::Expr> {
let fields = match *substr.fields {
Struct(ref fs) | EnumMatching(_, _, ref fs) => fs,
_ => cx.span_bug(trait_span, "impossible substructure")
};
fields.iter().fold(cx.expr_isize(trait_span, 0), |acc, ref item| {
if item.attrs.iter().find(|a| a.check_name("ignore")).is_some() {
acc
} else {
cx.expr_binary(item.span, ast::BiAdd, acc,
cx.expr_method_call(item.span,
item.self_.clone(),
substr.method_ident,
Vec::new()))
}
})
}
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