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Make #[derive(JSTraceable)] a procedural macro

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This commit is contained in:
Anthony Ramine 2016-11-02 22:43:37 +01:00
parent b0cac458b6
commit 391296278d
9 changed files with 98 additions and 68 deletions
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65
components/plugins/jstraceable.rs
View file

@ -2,13 +2,10 @@
* 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::{Expr, MetaItem, Mutability};
use syntax::ast::MetaItem;
use syntax::codemap::Span;
use syntax::ext::base::{Annotatable, ExtCtxt};
use syntax::ext::build::AstBuilder;
use syntax::ptr::P;
use syntax_ext::deriving::generic::{Struct, Substructure, TraitDef, ty};
use syntax_ext::deriving::generic::{combine_substructure, EnumMatching, FieldInfo, MethodDef};
pub fn expand_dom_struct(cx: &mut ExtCtxt, sp: Span, _: &MetaItem, anno: Annotatable) -> Annotatable {
if let Annotatable::Item(item) = anno {
@ -29,63 +26,3 @@ pub fn expand_dom_struct(cx: &mut ExtCtxt, sp: Span, _: &MetaItem, anno: Annotat
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 {
is_unsafe: false,
span: span,
attributes: Vec::new(),
path: ty::Path::new(vec!("dom", "bindings", "trace", "JSTraceable")),
additional_bounds: Vec::new(),
generics: ty::LifetimeBounds::empty(),
supports_unions: true,
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(Mutability::Mutable))),
ret_ty: ty::nil_ty(),
attributes: vec![quote_attr!(cx, #[inline])],
is_unsafe: false,
combine_substructure: combine_substructure(box jstraceable_substructure),
unify_fieldless_variants: true,
}
],
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))
}

3
components/plugins/lib.rs
View file

@ -25,7 +25,6 @@ extern crate rustc;
extern crate rustc_plugin;
#[macro_use]
extern crate syntax;
extern crate syntax_ext;
use rustc_plugin::Registry;
use syntax::ext::base::*;
@ -44,8 +43,6 @@ mod utils;
#[plugin_registrar]
pub fn plugin_registrar(reg: &mut Registry) {
reg.register_syntax_extension(intern("dom_struct"), MultiModifier(box jstraceable::expand_dom_struct));
reg.register_syntax_extension(intern("derive_JSTraceable"),
MultiDecorator(box jstraceable::expand_jstraceable));
reg.register_syntax_extension(intern("_generate_reflector"),
MultiDecorator(box reflector::expand_reflector));
reg.register_late_lint_pass(box lints::unrooted_must_root::UnrootedPass::new());