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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use syntax::ext::base::ExtCtxt;
use syntax::codemap::Span;
use syntax::ptr::P;
use syntax::ast::{Item, MetaItem, Expr};
use syntax::ast;
use syntax::attr;
use syntax::ext::build::AstBuilder;
use syntax::ext::deriving::generic::{combine_substructure, EnumMatching, FieldInfo, MethodDef, Struct, Substructure, TraitDef, ty};
use syntax::parse::token::InternedString;
pub fn expand_dom_struct(_: &mut ExtCtxt, _: Span, _: &MetaItem, item: P<Item>) -> P<Item> {
let mut item2 = (*item).clone();
item2.attrs.push(attr::mk_attr_outer(attr::mk_attr_id(), attr::mk_word_item(InternedString::new("must_root"))));
item2.attrs.push(attr::mk_attr_outer(attr::mk_attr_id(), attr::mk_word_item(InternedString::new("privatize"))));
item2.attrs.push(attr::mk_attr_outer(attr::mk_attr_id(), attr::mk_word_item(InternedString::new("jstraceable"))));
// The following attribute is only for internal usage
item2.attrs.push(attr::mk_attr_outer(attr::mk_attr_id(), attr::mk_word_item(InternedString::new("_generate_reflector"))));
P(item2)
}
/// Provides the hook to expand `#[jstraceable]` into an implementation of `JSTraceable`
///
/// The expansion basically calls `trace()` on all of the fields of the struct/enum, erroring if they do not implement the method.
pub fn expand_jstraceable(cx: &mut ExtCtxt, span: Span, mitem: &MetaItem, item: &Item, push: |P<Item>|) {
let trait_def = TraitDef {
span: span,
attributes: Vec::new(),
path: ty::Path::new(vec!("dom","bindings","trace","JSTraceable")),
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!(ty::Ptr(box ty::Literal(ty::Path::new(vec!("js","jsapi","JSTracer"))), ty::Raw(ast::MutMutable))),
ret_ty: ty::nil_ty(),
attributes: vec!(attr::mk_attr_outer(attr::mk_attr_id(),
attr::mk_name_value_item_str(InternedString::new("inline"),
InternedString::new("always")))),
combine_substructure: combine_substructure(|a, b, c| {
jstraceable_substructure(a, b, c)
})
}
)
};
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 jstraceable_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 `jstraceable`")
};
let trace_ident = substr.method_ident;
let call_trace = |span, thing_expr| {
let expr = cx.expr_method_call(span, thing_expr, trace_ident, vec!(state_expr.clone()));
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 `jstraceable`")
};
for &FieldInfo { ref self_, span, .. } in fields.iter() {
stmts.push(call_trace(span, self_.clone()));
}
cx.expr_block(cx.block(trait_span, stmts, None))
}
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