93 lines
2.9 KiB
Rust
93 lines
2.9 KiB
Rust
use crate::deriving::generic::ty::*;
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use crate::deriving::generic::*;
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use crate::deriving::{self, path_std, pathvec_std};
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use rustc_ast::ast::{Expr, MetaItem, Mutability};
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use rustc_ast::ptr::P;
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use rustc_expand::base::{Annotatable, ExtCtxt};
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use rustc_span::symbol::sym;
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use rustc_span::Span;
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pub fn expand_deriving_hash(
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cx: &mut ExtCtxt<'_>,
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span: Span,
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mitem: &MetaItem,
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item: &Annotatable,
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push: &mut dyn FnMut(Annotatable),
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) {
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let path = Path::new_(pathvec_std!(cx, hash::Hash), None, vec![], PathKind::Std);
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let typaram = "__H";
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let arg = Path::new_local(typaram);
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let hash_trait_def = TraitDef {
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span,
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attributes: Vec::new(),
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path,
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additional_bounds: Vec::new(),
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generics: LifetimeBounds::empty(),
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is_unsafe: false,
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supports_unions: false,
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methods: vec![MethodDef {
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name: "hash",
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generics: LifetimeBounds {
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lifetimes: Vec::new(),
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bounds: vec![(typaram, vec![path_std!(cx, hash::Hasher)])],
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},
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explicit_self: borrowed_explicit_self(),
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args: vec![(Ptr(Box::new(Literal(arg)), Borrowed(None, Mutability::Mut)), "state")],
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ret_ty: nil_ty(),
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attributes: vec![],
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is_unsafe: false,
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unify_fieldless_variants: true,
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combine_substructure: combine_substructure(Box::new(|a, b, c| {
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hash_substructure(a, b, c)
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})),
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}],
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associated_types: Vec::new(),
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};
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hash_trait_def.expand(cx, mitem, item, push);
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}
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fn hash_substructure(cx: &mut ExtCtxt<'_>, trait_span: Span, substr: &Substructure<'_>) -> P<Expr> {
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let state_expr = match &substr.nonself_args {
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&[o_f] => o_f,
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_ => cx.span_bug(trait_span, "incorrect number of arguments in `derive(Hash)`"),
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};
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let call_hash = |span, thing_expr| {
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let hash_path = {
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let strs = cx.std_path(&[sym::hash, sym::Hash, sym::hash]);
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cx.expr_path(cx.path_global(span, strs))
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};
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let ref_thing = cx.expr_addr_of(span, thing_expr);
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let expr = cx.expr_call(span, hash_path, vec![ref_thing, state_expr.clone()]);
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cx.stmt_expr(expr)
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};
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let mut stmts = Vec::new();
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let fields = match *substr.fields {
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Struct(_, ref fs) | EnumMatching(_, 1, .., ref fs) => fs,
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EnumMatching(.., ref fs) => {
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let variant_value = deriving::call_intrinsic(
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cx,
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trait_span,
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"discriminant_value",
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vec![cx.expr_self(trait_span)],
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);
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stmts.push(call_hash(trait_span, variant_value));
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fs
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}
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_ => cx.span_bug(trait_span, "impossible substructure in `derive(Hash)`"),
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};
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stmts.extend(
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fields.iter().map(|FieldInfo { ref self_, span, .. }| call_hash(*span, self_.clone())),
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);
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cx.expr_block(cx.block(trait_span, stmts))
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}
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