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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::ast;
use syntax::ast::{MetaItem, Expr};
use syntax::codemap::Span;
use syntax::ext::base::{Annotatable, ExtCtxt};
use syntax::ext::build::AstBuilder;
use syntax::ext::deriving::generic::{Struct, Substructure, TraitDef, ty};
use syntax::ext::deriving::generic::{combine_substructure, EnumMatching, FieldInfo, MethodDef};
use syntax::ptr::P;
pub fn expand_dom_struct(cx: &mut ExtCtxt, sp: Span, _: &MetaItem, anno: Annotatable) -> Annotatable {
if let Annotatable::Item(item) = anno {
let mut item2 = (*item).clone();
item2.attrs.push(quote_attr!(cx, #[must_root]));
item2.attrs.push(quote_attr!(cx, #[privatize]));
item2.attrs.push(quote_attr!(cx, #[derive(JSTraceable)]));
// The following attributes are only for internal usage
item2.attrs.push(quote_attr!(cx, #[_generate_reflector]));
// #[dom_struct] gets consumed, so this lets us keep around a residue
// Do NOT register a modifier/decorator on this attribute
item2.attrs.push(quote_attr!(cx, #[_dom_struct_marker]));
Annotatable::Item(P(item2))
} else {
cx.span_err(sp, "#[dom_struct] applied to something other than a struct");
anno
}
}
/// Provides the hook to expand `#[derive(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: &Annotatable,
push: &mut FnMut(Annotatable)) {
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![quote_attr!(cx, #[inline])],
is_unsafe: false,
combine_substructure: combine_substructure(box jstraceable_substructure)
}
],
associated_types: vec![],
};
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 = if substr.nonself_args.len() == 1 {
&substr.nonself_args[0]
} else {
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 {
stmts.push(call_trace(span, self_.clone()));
}
cx.expr_block(cx.block(trait_span, stmts, None))
}
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