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#![feature(plugin_registrar, box_syntax)]
#![feature(rustc_private)]
#[macro_use]
extern crate syntax;
extern crate syntax_ext;
#[macro_use]
extern crate rustc;
extern crate rustc_plugin;
use rustc_plugin::Registry;
use syntax::parse::token::intern;
use syntax::attr::AttrMetaMethods;
use syntax::ext::base::{Annotatable, ExtCtxt, MultiDecorator};
use syntax::codemap::Span;
use syntax::ptr::P;
use syntax::ast::{MetaItem, Expr};
use syntax::ext::build::AstBuilder;
use syntax_ext::deriving::generic::{combine_substructure, EnumMatching, FieldInfo, MethodDef, Struct, Substructure, TraitDef, ty};
#[plugin_registrar]
pub fn plugin_registrar(reg: &mut Registry) {
reg.register_syntax_extension(intern("derive_Trace"), MultiDecorator(box expand_trace))
}
pub fn expand_trace(cx: &mut ExtCtxt, span: Span, mitem: &MetaItem, item: &Annotatable, push: &mut FnMut(Annotatable)) {
let trait_def = TraitDef {
span: span,
attributes: Vec::new(),
path: ty::Path::new(vec!("gc", "Trace")),
additional_bounds: Vec::new(),
generics: ty::LifetimeBounds::empty(),
methods: vec![
MethodDef {
name: "trace",
generics: ty::LifetimeBounds::empty(),
explicit_self: ty::borrowed_explicit_self(),
args: vec!(),
ret_ty: ty::nil_ty(),
attributes: vec![],
is_unsafe: true,
combine_substructure: combine_substructure(box trace_substructure),
unify_fieldless_variants: false,
},
MethodDef {
name: "root",
generics: ty::LifetimeBounds::empty(),
explicit_self: ty::borrowed_explicit_self(),
args: vec!(),
ret_ty: ty::nil_ty(),
attributes: vec![],
is_unsafe: true,
combine_substructure: combine_substructure(box trace_substructure),
unify_fieldless_variants: false,
},
MethodDef {
name: "unroot",
generics: ty::LifetimeBounds::empty(),
explicit_self: ty::borrowed_explicit_self(),
args: vec!(),
ret_ty: ty::nil_ty(),
attributes: vec![],
is_unsafe: true,
combine_substructure: combine_substructure(box trace_substructure),
unify_fieldless_variants: false,
}
],
associated_types: vec![],
is_unsafe: true,
};
trait_def.expand(cx, mitem, item, push)
}
fn trace_substructure(cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure) -> P<Expr> {
let trace_path = {
let strs = vec![
cx.ident_of("gc"),
cx.ident_of("trace"),
cx.ident_of("Trace"),
substr.method_ident,
];
cx.expr_path(cx.path_global(trait_span, strs))
};
let call_trace = |span, thing_expr| {
let expr = cx.expr_call(span, trace_path.clone(), vec!(cx.expr_addr_of(span, thing_expr)));
cx.stmt_expr(expr)
};
let mut stmts = Vec::new();
let fields = match *substr.fields {
Struct(_, ref fs) | EnumMatching(_, _, ref fs) => fs,
_ => cx.span_bug(trait_span, "impossible substructure in `#[derive(Trace)]`")
};
for &FieldInfo { ref self_, span, attrs, .. } in fields.iter() {
if attrs.iter().all(|ref a| !a.check_name("unsafe_ignore_trace")) {
stmts.push(call_trace(span, self_.clone()));
}
}
cx.expr_block(cx.block(trait_span, stmts))
}