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use deriving::generic::*;
use deriving::generic::ty::*;
use syntax::ast::{self, Expr, MetaItem};
use syntax::ext::base::{Annotatable, ExtCtxt};
use syntax::ext::build::AstBuilder;
use syntax::ptr::P;
use syntax::symbol::Symbol;
use syntax_pos::Span;
pub fn expand_deriving_eq(cx: &mut ExtCtxt,
span: Span,
mitem: &MetaItem,
item: &Annotatable,
push: &mut FnMut(Annotatable)) {
let inline = cx.meta_word(span, Symbol::intern("inline"));
let hidden = cx.meta_list_item_word(span, Symbol::intern("hidden"));
let doc = cx.meta_list(span, Symbol::intern("doc"), vec![hidden]);
let attrs = vec![cx.attribute(span, inline), cx.attribute(span, doc)];
let trait_def = TraitDef {
span: span,
attributes: Vec::new(),
path: path_std!(cx, core::cmp::Eq),
additional_bounds: Vec::new(),
generics: LifetimeBounds::empty(),
is_unsafe: false,
supports_unions: true,
methods: vec![MethodDef {
name: "assert_receiver_is_total_eq",
generics: LifetimeBounds::empty(),
explicit_self: borrowed_explicit_self(),
args: vec![],
ret_ty: nil_ty(),
attributes: attrs,
is_unsafe: false,
unify_fieldless_variants: true,
combine_substructure: combine_substructure(Box::new(|a, b, c| {
cs_total_eq_assert(a, b, c)
})),
}],
associated_types: Vec::new(),
};
trait_def.expand_ext(cx, mitem, item, push, true)
}
fn cs_total_eq_assert(cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure) -> P<Expr> {
fn assert_ty_bounds(cx: &mut ExtCtxt, stmts: &mut Vec<ast::Stmt>,
ty: P<ast::Ty>, span: Span, helper_name: &str) {
let span = super::allow_unstable(cx, span, "derive(Eq)");
let assert_path = cx.path_all(span, true,
cx.std_path(&["cmp", helper_name]),
vec![], vec![ty], vec![]);
stmts.push(cx.stmt_let_type_only(span, cx.ty_path(assert_path)));
}
fn process_variant(cx: &mut ExtCtxt, stmts: &mut Vec<ast::Stmt>, variant: &ast::VariantData) {
for field in variant.fields() {
assert_ty_bounds(cx, stmts, field.ty.clone(), field.span, "AssertParamIsEq");
}
}
let mut stmts = Vec::new();
match *substr.fields {
StaticStruct(vdata, ..) => {
process_variant(cx, &mut stmts, vdata);
}
StaticEnum(enum_def, ..) => {
for variant in &enum_def.variants {
process_variant(cx, &mut stmts, &variant.node.data);
}
}
_ => cx.span_bug(trait_span, "unexpected substructure in `derive(Eq)`")
}
cx.expr_block(cx.block(trait_span, stmts))
}