1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Lowers the AST to the HIR.
13 // Since the AST and HIR are fairly similar, this is mostly a simple procedure,
14 // much like a fold. Where lowering involves a bit more work things get more
15 // interesting and there are some invariants you should know about. These mostly
16 // concern spans and ids.
18 // Spans are assigned to AST nodes during parsing and then are modified during
19 // expansion to indicate the origin of a node and the process it went through
20 // being expanded. Ids are assigned to AST nodes just before lowering.
22 // For the simpler lowering steps, ids and spans should be preserved. Unlike
23 // expansion we do not preserve the process of lowering in the spans, so spans
24 // should not be modified here. When creating a new node (as opposed to
25 // 'folding' an existing one), then you create a new id using `next_id()`.
27 // You must ensure that ids are unique. That means that you should only use the
28 // id from an AST node in a single HIR node (you can assume that AST node ids
29 // are unique). Every new node must have a unique id. Avoid cloning HIR nodes.
30 // If you do, you must then set the new node's id to a fresh one.
32 // Lowering must be reproducable (the compiler only lowers once, but tools and
33 // custom lints may lower an AST node to a HIR node to interact with the
34 // compiler). The most interesting bit of this is ids - if you lower an AST node
35 // and create new HIR nodes with fresh ids, when re-lowering the same node, you
36 // must ensure you get the same ids! To do this, we keep track of the next id
37 // when we translate a node which requires new ids. By checking this cache and
38 // using node ids starting with the cached id, we ensure ids are reproducible.
39 // To use this system, you just need to hold on to a CachedIdSetter object
40 // whilst lowering. This is an RAII object that takes care of setting and
41 // restoring the cached id, etc.
43 // This whole system relies on node ids being incremented one at a time and
44 // all increments being for lowering. This means that you should not call any
45 // non-lowering function which will use new node ids.
47 // We must also cache gensym'ed Idents to ensure that we get the same Ident
48 // every time we lower a node with gensym'ed names. One consequence of this is
49 // that you can only gensym a name once in a lowering (you don't need to worry
50 // about nested lowering though). That's because we cache based on the name and
51 // the currently cached node id, which is unique per lowered node.
53 // Spans are used for error messages and for tools to map semantics back to
54 // source code. It is therefore not as important with spans as ids to be strict
55 // about use (you can't break the compiler by screwing up a span). Obviously, a
56 // HIR node can only have a single span. But multiple nodes can have the same
57 // span and spans don't need to be kept in order, etc. Where code is preserved
58 // by lowering, it should have the same span as in the AST. Where HIR nodes are
59 // new it is probably best to give a span for the whole AST node being lowered.
60 // All nodes should have real spans, don't use dummy spans. Tools are likely to
61 // get confused if the spans from leaf AST nodes occur in multiple places
62 // in the HIR, especially for multiple identifiers.
66 use std::collections::BTreeMap;
67 use std::collections::HashMap;
69 use syntax::attr::{ThinAttributes, ThinAttributesExt};
70 use syntax::ext::mtwt;
72 use syntax::codemap::{respan, Spanned, Span};
73 use syntax::parse::token;
74 use syntax::std_inject;
75 use syntax::visit::{self, Visitor};
77 use std::cell::{Cell, RefCell};
79 pub struct LoweringContext<'a> {
80 crate_root: Option<&'static str>,
81 // Map AST ids to ids used for expanded nodes.
82 id_cache: RefCell<HashMap<NodeId, NodeId>>,
83 // Use if there are no cached ids for the current node.
84 id_assigner: &'a NodeIdAssigner,
85 // 0 == no cached id. Must be incremented to align with previous id
88 // Keep track of gensym'ed idents.
89 gensym_cache: RefCell<HashMap<(NodeId, &'static str), hir::Ident>>,
90 // A copy of cached_id, but is also set to an id while a node is lowered for
92 gensym_key: Cell<u32>,
95 impl<'a, 'hir> LoweringContext<'a> {
96 pub fn new(id_assigner: &'a NodeIdAssigner, c: Option<&Crate>) -> LoweringContext<'a> {
97 let crate_root = c.and_then(|c| {
98 if std_inject::no_core(c) {
100 } else if std_inject::no_std(c) {
108 crate_root: crate_root,
109 id_cache: RefCell::new(HashMap::new()),
110 id_assigner: id_assigner,
111 cached_id: Cell::new(0),
112 gensym_cache: RefCell::new(HashMap::new()),
113 gensym_key: Cell::new(0),
117 fn next_id(&self) -> NodeId {
118 let cached_id = self.cached_id.get();
120 return self.id_assigner.next_node_id();
123 self.cached_id.set(cached_id + 1);
127 fn str_to_ident(&self, s: &'static str) -> hir::Ident {
128 let gensym_key = self.gensym_key.get();
130 return hir::Ident::from_name(token::gensym(s));
133 let cached = self.gensym_cache.borrow().contains_key(&(gensym_key, s));
135 self.gensym_cache.borrow()[&(gensym_key, s)]
137 let result = hir::Ident::from_name(token::gensym(s));
138 self.gensym_cache.borrow_mut().insert((gensym_key, s), result);
144 // Utility fn for setting and unsetting the cached id.
145 fn cache_ids<'a, OP, R>(lctx: &LoweringContext, expr_id: NodeId, op: OP) -> R
146 where OP: FnOnce(&LoweringContext) -> R
148 // Only reset the id if it was previously 0, i.e., was not cached.
149 // If it was cached, we are in a nested node, but our id count will
150 // still count towards the parent's count.
151 let reset_cached_id = lctx.cached_id.get() == 0;
152 // We always reset gensym_key so that if we use the same name in a nested
153 // node and after that node, they get different values.
154 let old_gensym_key = lctx.gensym_key.get();
157 let id_cache: &mut HashMap<_, _> = &mut lctx.id_cache.borrow_mut();
159 if id_cache.contains_key(&expr_id) {
160 let cached_id = lctx.cached_id.get();
162 // We're entering a node where we need to track ids, but are not
164 lctx.cached_id.set(id_cache[&expr_id]);
166 // We're already tracking - check that the tracked id is the same
167 // as the expected id.
168 assert!(cached_id == id_cache[&expr_id], "id mismatch");
170 lctx.gensym_key.set(id_cache[&expr_id]);
172 // We've never lowered this node before, remember it for next time.
173 let next_id = lctx.id_assigner.peek_node_id();
174 id_cache.insert(expr_id, next_id);
175 lctx.gensym_key.set(next_id);
176 // self.cached_id is not set when we lower a node for the first time,
177 // only on re-lowering.
181 let result = op(lctx);
184 lctx.cached_id.set(0);
186 lctx.gensym_key.set(old_gensym_key);
191 pub fn lower_ident(_lctx: &LoweringContext, ident: Ident) -> hir::Ident {
193 name: mtwt::resolve(ident),
194 unhygienic_name: ident.name,
198 pub fn lower_attrs(_lctx: &LoweringContext, attrs: &Vec<Attribute>) -> hir::HirVec<Attribute> {
202 pub fn lower_view_path(lctx: &LoweringContext, view_path: &ViewPath) -> P<hir::ViewPath> {
204 node: match view_path.node {
205 ViewPathSimple(ident, ref path) => {
206 hir::ViewPathSimple(ident.name, lower_path(lctx, path))
208 ViewPathGlob(ref path) => {
209 hir::ViewPathGlob(lower_path(lctx, path))
211 ViewPathList(ref path, ref path_list_idents) => {
212 hir::ViewPathList(lower_path(lctx, path),
213 path_list_idents.iter()
214 .map(lower_path_list_item)
218 span: view_path.span,
222 fn lower_path_list_item(path_list_ident: &PathListItem) -> hir::PathListItem {
224 node: match path_list_ident.node {
225 PathListItemKind::Ident { id, name, rename } => hir::PathListIdent {
228 rename: rename.map(|x| x.name),
230 PathListItemKind::Mod { id, rename } => hir::PathListMod {
232 rename: rename.map(|x| x.name),
235 span: path_list_ident.span,
239 pub fn lower_arm(lctx: &LoweringContext, arm: &Arm) -> hir::Arm {
241 attrs: lower_attrs(lctx, &arm.attrs),
242 pats: arm.pats.iter().map(|x| lower_pat(lctx, x)).collect(),
243 guard: arm.guard.as_ref().map(|ref x| lower_expr(lctx, x)),
244 body: lower_expr(lctx, &arm.body),
248 pub fn lower_decl(lctx: &LoweringContext, d: &Decl) -> P<hir::Decl> {
250 DeclKind::Local(ref l) => P(Spanned {
251 node: hir::DeclLocal(lower_local(lctx, l)),
254 DeclKind::Item(ref it) => P(Spanned {
255 node: hir::DeclItem(lower_item_id(lctx, it)),
261 pub fn lower_ty_binding(lctx: &LoweringContext, b: &TypeBinding) -> hir::TypeBinding {
265 ty: lower_ty(lctx, &b.ty),
270 pub fn lower_ty(lctx: &LoweringContext, t: &Ty) -> P<hir::Ty> {
271 use syntax::ast::TyKind::*;
275 Infer => hir::TyInfer,
276 Vec(ref ty) => hir::TyVec(lower_ty(lctx, ty)),
277 Ptr(ref mt) => hir::TyPtr(lower_mt(lctx, mt)),
278 Rptr(ref region, ref mt) => {
279 hir::TyRptr(lower_opt_lifetime(lctx, region), lower_mt(lctx, mt))
282 hir::TyBareFn(P(hir::BareFnTy {
283 lifetimes: lower_lifetime_defs(lctx, &f.lifetimes),
284 unsafety: lower_unsafety(lctx, f.unsafety),
286 decl: lower_fn_decl(lctx, &f.decl),
289 Tup(ref tys) => hir::TyTup(tys.iter().map(|ty| lower_ty(lctx, ty)).collect()),
291 return lower_ty(lctx, ty);
293 Path(ref qself, ref path) => {
294 let qself = qself.as_ref().map(|&QSelf { ref ty, position }| {
296 ty: lower_ty(lctx, ty),
300 hir::TyPath(qself, lower_path(lctx, path))
302 ObjectSum(ref ty, ref bounds) => {
303 hir::TyObjectSum(lower_ty(lctx, ty), lower_bounds(lctx, bounds))
305 FixedLengthVec(ref ty, ref e) => {
306 hir::TyFixedLengthVec(lower_ty(lctx, ty), lower_expr(lctx, e))
308 Typeof(ref expr) => {
309 hir::TyTypeof(lower_expr(lctx, expr))
311 PolyTraitRef(ref bounds) => {
312 hir::TyPolyTraitRef(bounds.iter().map(|b| lower_ty_param_bound(lctx, b)).collect())
314 Mac(_) => panic!("TyMac should have been expanded by now."),
320 pub fn lower_foreign_mod(lctx: &LoweringContext, fm: &ForeignMod) -> hir::ForeignMod {
323 items: fm.items.iter().map(|x| lower_foreign_item(lctx, x)).collect(),
327 pub fn lower_variant(lctx: &LoweringContext, v: &Variant) -> hir::Variant {
329 node: hir::Variant_ {
330 name: v.node.name.name,
331 attrs: lower_attrs(lctx, &v.node.attrs),
332 data: lower_variant_data(lctx, &v.node.data),
333 disr_expr: v.node.disr_expr.as_ref().map(|e| lower_expr(lctx, e)),
339 // Path segments are usually unhygienic, hygienic path segments can occur only in
340 // identifier-like paths originating from `ExprPath`.
341 // Make life simpler for rustc_resolve by renaming only such segments.
342 pub fn lower_path_full(lctx: &LoweringContext, p: &Path, maybe_hygienic: bool) -> hir::Path {
343 let maybe_hygienic = maybe_hygienic && !p.global && p.segments.len() == 1;
348 .map(|&PathSegment { identifier, ref parameters }| {
350 identifier: if maybe_hygienic {
351 lower_ident(lctx, identifier)
353 hir::Ident::from_name(identifier.name)
355 parameters: lower_path_parameters(lctx, parameters),
363 pub fn lower_path(lctx: &LoweringContext, p: &Path) -> hir::Path {
364 lower_path_full(lctx, p, false)
367 pub fn lower_path_parameters(lctx: &LoweringContext,
368 path_parameters: &PathParameters)
369 -> hir::PathParameters {
370 match *path_parameters {
371 PathParameters::AngleBracketed(ref data) =>
372 hir::AngleBracketedParameters(lower_angle_bracketed_parameter_data(lctx, data)),
373 PathParameters::Parenthesized(ref data) =>
374 hir::ParenthesizedParameters(lower_parenthesized_parameter_data(lctx, data)),
378 pub fn lower_angle_bracketed_parameter_data(lctx: &LoweringContext,
379 data: &AngleBracketedParameterData)
380 -> hir::AngleBracketedParameterData {
381 let &AngleBracketedParameterData { ref lifetimes, ref types, ref bindings } = data;
382 hir::AngleBracketedParameterData {
383 lifetimes: lower_lifetimes(lctx, lifetimes),
384 types: types.iter().map(|ty| lower_ty(lctx, ty)).collect(),
385 bindings: bindings.iter().map(|b| lower_ty_binding(lctx, b)).collect(),
389 pub fn lower_parenthesized_parameter_data(lctx: &LoweringContext,
390 data: &ParenthesizedParameterData)
391 -> hir::ParenthesizedParameterData {
392 let &ParenthesizedParameterData { ref inputs, ref output, span } = data;
393 hir::ParenthesizedParameterData {
394 inputs: inputs.iter().map(|ty| lower_ty(lctx, ty)).collect(),
395 output: output.as_ref().map(|ty| lower_ty(lctx, ty)),
400 pub fn lower_local(lctx: &LoweringContext, l: &Local) -> P<hir::Local> {
403 ty: l.ty.as_ref().map(|t| lower_ty(lctx, t)),
404 pat: lower_pat(lctx, &l.pat),
405 init: l.init.as_ref().map(|e| lower_expr(lctx, e)),
407 attrs: l.attrs.clone(),
411 pub fn lower_explicit_self_underscore(lctx: &LoweringContext,
413 -> hir::ExplicitSelf_ {
415 SelfKind::Static => hir::SelfStatic,
416 SelfKind::Value(v) => hir::SelfValue(v.name),
417 SelfKind::Region(ref lifetime, m, ident) => {
418 hir::SelfRegion(lower_opt_lifetime(lctx, lifetime),
419 lower_mutability(lctx, m),
422 SelfKind::Explicit(ref typ, ident) => {
423 hir::SelfExplicit(lower_ty(lctx, typ), ident.name)
428 pub fn lower_mutability(_lctx: &LoweringContext, m: Mutability) -> hir::Mutability {
430 Mutability::Mutable => hir::MutMutable,
431 Mutability::Immutable => hir::MutImmutable,
435 pub fn lower_explicit_self(lctx: &LoweringContext, s: &ExplicitSelf) -> hir::ExplicitSelf {
437 node: lower_explicit_self_underscore(lctx, &s.node),
442 pub fn lower_arg(lctx: &LoweringContext, arg: &Arg) -> hir::Arg {
445 pat: lower_pat(lctx, &arg.pat),
446 ty: lower_ty(lctx, &arg.ty),
450 pub fn lower_fn_decl(lctx: &LoweringContext, decl: &FnDecl) -> P<hir::FnDecl> {
452 inputs: decl.inputs.iter().map(|x| lower_arg(lctx, x)).collect(),
453 output: match decl.output {
454 FunctionRetTy::Ty(ref ty) => hir::Return(lower_ty(lctx, ty)),
455 FunctionRetTy::Default(span) => hir::DefaultReturn(span),
456 FunctionRetTy::None(span) => hir::NoReturn(span),
458 variadic: decl.variadic,
462 pub fn lower_ty_param_bound(lctx: &LoweringContext, tpb: &TyParamBound) -> hir::TyParamBound {
464 TraitTyParamBound(ref ty, modifier) => {
465 hir::TraitTyParamBound(lower_poly_trait_ref(lctx, ty),
466 lower_trait_bound_modifier(lctx, modifier))
468 RegionTyParamBound(ref lifetime) => {
469 hir::RegionTyParamBound(lower_lifetime(lctx, lifetime))
474 pub fn lower_ty_param(lctx: &LoweringContext, tp: &TyParam) -> hir::TyParam {
478 bounds: lower_bounds(lctx, &tp.bounds),
479 default: tp.default.as_ref().map(|x| lower_ty(lctx, x)),
484 pub fn lower_ty_params(lctx: &LoweringContext,
486 -> hir::HirVec<hir::TyParam> {
487 tps.iter().map(|tp| lower_ty_param(lctx, tp)).collect()
490 pub fn lower_lifetime(_lctx: &LoweringContext, l: &Lifetime) -> hir::Lifetime {
498 pub fn lower_lifetime_def(lctx: &LoweringContext, l: &LifetimeDef) -> hir::LifetimeDef {
500 lifetime: lower_lifetime(lctx, &l.lifetime),
501 bounds: lower_lifetimes(lctx, &l.bounds),
505 pub fn lower_lifetimes(lctx: &LoweringContext, lts: &Vec<Lifetime>) -> hir::HirVec<hir::Lifetime> {
506 lts.iter().map(|l| lower_lifetime(lctx, l)).collect()
509 pub fn lower_lifetime_defs(lctx: &LoweringContext,
510 lts: &Vec<LifetimeDef>)
511 -> hir::HirVec<hir::LifetimeDef> {
512 lts.iter().map(|l| lower_lifetime_def(lctx, l)).collect()
515 pub fn lower_opt_lifetime(lctx: &LoweringContext,
516 o_lt: &Option<Lifetime>)
517 -> Option<hir::Lifetime> {
518 o_lt.as_ref().map(|lt| lower_lifetime(lctx, lt))
521 pub fn lower_generics(lctx: &LoweringContext, g: &Generics) -> hir::Generics {
523 ty_params: lower_ty_params(lctx, &g.ty_params),
524 lifetimes: lower_lifetime_defs(lctx, &g.lifetimes),
525 where_clause: lower_where_clause(lctx, &g.where_clause),
529 pub fn lower_where_clause(lctx: &LoweringContext, wc: &WhereClause) -> hir::WhereClause {
532 predicates: wc.predicates
534 .map(|predicate| lower_where_predicate(lctx, predicate))
539 pub fn lower_where_predicate(lctx: &LoweringContext,
540 pred: &WherePredicate)
541 -> hir::WherePredicate {
543 WherePredicate::BoundPredicate(WhereBoundPredicate{ ref bound_lifetimes,
547 hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
548 bound_lifetimes: lower_lifetime_defs(lctx, bound_lifetimes),
549 bounded_ty: lower_ty(lctx, bounded_ty),
550 bounds: bounds.iter().map(|x| lower_ty_param_bound(lctx, x)).collect(),
554 WherePredicate::RegionPredicate(WhereRegionPredicate{ ref lifetime,
557 hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
559 lifetime: lower_lifetime(lctx, lifetime),
560 bounds: bounds.iter().map(|bound| lower_lifetime(lctx, bound)).collect(),
563 WherePredicate::EqPredicate(WhereEqPredicate{ id,
567 hir::WherePredicate::EqPredicate(hir::WhereEqPredicate {
569 path: lower_path(lctx, path),
570 ty: lower_ty(lctx, ty),
577 pub fn lower_variant_data(lctx: &LoweringContext, vdata: &VariantData) -> hir::VariantData {
579 VariantData::Struct(ref fields, id) => {
580 hir::VariantData::Struct(fields.iter()
582 .map(|f| lower_struct_field(lctx, f))
586 VariantData::Tuple(ref fields, id) => {
587 hir::VariantData::Tuple(fields.iter()
589 .map(|f| lower_struct_field(lctx, f))
593 VariantData::Unit(id) => hir::VariantData::Unit(id),
597 pub fn lower_trait_ref(lctx: &LoweringContext, p: &TraitRef) -> hir::TraitRef {
599 path: lower_path(lctx, &p.path),
604 pub fn lower_poly_trait_ref(lctx: &LoweringContext, p: &PolyTraitRef) -> hir::PolyTraitRef {
606 bound_lifetimes: lower_lifetime_defs(lctx, &p.bound_lifetimes),
607 trait_ref: lower_trait_ref(lctx, &p.trait_ref),
612 pub fn lower_struct_field(lctx: &LoweringContext,
613 (index, f): (usize, &StructField))
614 -> hir::StructField {
618 name: f.node.ident().map(|ident| ident.name)
619 .unwrap_or(token::intern(&index.to_string())),
620 vis: lower_visibility(lctx, f.node.kind.visibility()),
621 ty: lower_ty(lctx, &f.node.ty),
622 attrs: lower_attrs(lctx, &f.node.attrs),
626 pub fn lower_field(lctx: &LoweringContext, f: &Field) -> hir::Field {
628 name: respan(f.ident.span, f.ident.node.name),
629 expr: lower_expr(lctx, &f.expr),
634 pub fn lower_mt(lctx: &LoweringContext, mt: &MutTy) -> hir::MutTy {
636 ty: lower_ty(lctx, &mt.ty),
637 mutbl: lower_mutability(lctx, mt.mutbl),
641 pub fn lower_opt_bounds(lctx: &LoweringContext,
642 b: &Option<TyParamBounds>)
643 -> Option<hir::TyParamBounds> {
644 b.as_ref().map(|ref bounds| lower_bounds(lctx, bounds))
647 fn lower_bounds(lctx: &LoweringContext, bounds: &TyParamBounds) -> hir::TyParamBounds {
648 bounds.iter().map(|bound| lower_ty_param_bound(lctx, bound)).collect()
651 pub fn lower_block(lctx: &LoweringContext, b: &Block) -> P<hir::Block> {
654 stmts: b.stmts.iter().map(|s| lower_stmt(lctx, s)).collect(),
655 expr: b.expr.as_ref().map(|ref x| lower_expr(lctx, x)),
656 rules: lower_block_check_mode(lctx, &b.rules),
661 pub fn lower_item_kind(lctx: &LoweringContext, i: &ItemKind) -> hir::Item_ {
663 ItemKind::ExternCrate(string) => hir::ItemExternCrate(string),
664 ItemKind::Use(ref view_path) => {
665 hir::ItemUse(lower_view_path(lctx, view_path))
667 ItemKind::Static(ref t, m, ref e) => {
668 hir::ItemStatic(lower_ty(lctx, t),
669 lower_mutability(lctx, m),
672 ItemKind::Const(ref t, ref e) => {
673 hir::ItemConst(lower_ty(lctx, t), lower_expr(lctx, e))
675 ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
676 hir::ItemFn(lower_fn_decl(lctx, decl),
677 lower_unsafety(lctx, unsafety),
678 lower_constness(lctx, constness),
680 lower_generics(lctx, generics),
681 lower_block(lctx, body))
683 ItemKind::Mod(ref m) => hir::ItemMod(lower_mod(lctx, m)),
684 ItemKind::ForeignMod(ref nm) => hir::ItemForeignMod(lower_foreign_mod(lctx, nm)),
685 ItemKind::Ty(ref t, ref generics) => {
686 hir::ItemTy(lower_ty(lctx, t), lower_generics(lctx, generics))
688 ItemKind::Enum(ref enum_definition, ref generics) => {
689 hir::ItemEnum(hir::EnumDef {
690 variants: enum_definition.variants
692 .map(|x| lower_variant(lctx, x))
695 lower_generics(lctx, generics))
697 ItemKind::Struct(ref struct_def, ref generics) => {
698 let struct_def = lower_variant_data(lctx, struct_def);
699 hir::ItemStruct(struct_def, lower_generics(lctx, generics))
701 ItemKind::DefaultImpl(unsafety, ref trait_ref) => {
702 hir::ItemDefaultImpl(lower_unsafety(lctx, unsafety),
703 lower_trait_ref(lctx, trait_ref))
705 ItemKind::Impl(unsafety, polarity, ref generics, ref ifce, ref ty, ref impl_items) => {
706 let new_impl_items = impl_items.iter()
707 .map(|item| lower_impl_item(lctx, item))
709 let ifce = ifce.as_ref().map(|trait_ref| lower_trait_ref(lctx, trait_ref));
710 hir::ItemImpl(lower_unsafety(lctx, unsafety),
711 lower_impl_polarity(lctx, polarity),
712 lower_generics(lctx, generics),
717 ItemKind::Trait(unsafety, ref generics, ref bounds, ref items) => {
718 let bounds = lower_bounds(lctx, bounds);
719 let items = items.iter().map(|item| lower_trait_item(lctx, item)).collect();
720 hir::ItemTrait(lower_unsafety(lctx, unsafety),
721 lower_generics(lctx, generics),
725 ItemKind::Mac(_) => panic!("Shouldn't still be around"),
729 pub fn lower_trait_item(lctx: &LoweringContext, i: &TraitItem) -> hir::TraitItem {
733 attrs: lower_attrs(lctx, &i.attrs),
735 TraitItemKind::Const(ref ty, ref default) => {
736 hir::ConstTraitItem(lower_ty(lctx, ty),
737 default.as_ref().map(|x| lower_expr(lctx, x)))
739 TraitItemKind::Method(ref sig, ref body) => {
740 hir::MethodTraitItem(lower_method_sig(lctx, sig),
741 body.as_ref().map(|x| lower_block(lctx, x)))
743 TraitItemKind::Type(ref bounds, ref default) => {
744 hir::TypeTraitItem(lower_bounds(lctx, bounds),
745 default.as_ref().map(|x| lower_ty(lctx, x)))
752 pub fn lower_impl_item(lctx: &LoweringContext, i: &ImplItem) -> hir::ImplItem {
756 attrs: lower_attrs(lctx, &i.attrs),
757 vis: lower_visibility(lctx, i.vis),
759 ImplItemKind::Const(ref ty, ref expr) => {
760 hir::ImplItemKind::Const(lower_ty(lctx, ty), lower_expr(lctx, expr))
762 ImplItemKind::Method(ref sig, ref body) => {
763 hir::ImplItemKind::Method(lower_method_sig(lctx, sig), lower_block(lctx, body))
765 ImplItemKind::Type(ref ty) => hir::ImplItemKind::Type(lower_ty(lctx, ty)),
766 ImplItemKind::Macro(..) => panic!("Shouldn't exist any more"),
772 pub fn lower_mod(lctx: &LoweringContext, m: &Mod) -> hir::Mod {
775 item_ids: m.items.iter().map(|x| lower_item_id(lctx, x)).collect(),
779 struct ItemLowerer<'lcx, 'interner: 'lcx> {
780 items: BTreeMap<NodeId, hir::Item>,
781 lctx: &'lcx LoweringContext<'interner>,
784 impl<'lcx, 'interner> Visitor<'lcx> for ItemLowerer<'lcx, 'interner> {
785 fn visit_item(&mut self, item: &'lcx Item) {
786 self.items.insert(item.id, lower_item(self.lctx, item));
787 visit::walk_item(self, item);
791 pub fn lower_crate(lctx: &LoweringContext, c: &Crate) -> hir::Crate {
793 let mut item_lowerer = ItemLowerer { items: BTreeMap::new(), lctx: lctx };
794 visit::walk_crate(&mut item_lowerer, c);
799 module: lower_mod(lctx, &c.module),
800 attrs: lower_attrs(lctx, &c.attrs),
801 config: c.config.clone().into(),
803 exported_macros: c.exported_macros.iter().map(|m| lower_macro_def(lctx, m)).collect(),
808 pub fn lower_macro_def(lctx: &LoweringContext, m: &MacroDef) -> hir::MacroDef {
811 attrs: lower_attrs(lctx, &m.attrs),
814 imported_from: m.imported_from.map(|x| x.name),
816 use_locally: m.use_locally,
817 allow_internal_unstable: m.allow_internal_unstable,
818 body: m.body.clone().into(),
822 pub fn lower_item_id(_lctx: &LoweringContext, i: &Item) -> hir::ItemId {
823 hir::ItemId { id: i.id }
826 pub fn lower_item(lctx: &LoweringContext, i: &Item) -> hir::Item {
827 let node = lower_item_kind(lctx, &i.node);
832 attrs: lower_attrs(lctx, &i.attrs),
834 vis: lower_visibility(lctx, i.vis),
839 pub fn lower_foreign_item(lctx: &LoweringContext, i: &ForeignItem) -> hir::ForeignItem {
843 attrs: lower_attrs(lctx, &i.attrs),
845 ForeignItemKind::Fn(ref fdec, ref generics) => {
846 hir::ForeignItemFn(lower_fn_decl(lctx, fdec), lower_generics(lctx, generics))
848 ForeignItemKind::Static(ref t, m) => {
849 hir::ForeignItemStatic(lower_ty(lctx, t), m)
852 vis: lower_visibility(lctx, i.vis),
857 pub fn lower_method_sig(lctx: &LoweringContext, sig: &MethodSig) -> hir::MethodSig {
859 generics: lower_generics(lctx, &sig.generics),
861 explicit_self: lower_explicit_self(lctx, &sig.explicit_self),
862 unsafety: lower_unsafety(lctx, sig.unsafety),
863 constness: lower_constness(lctx, sig.constness),
864 decl: lower_fn_decl(lctx, &sig.decl),
868 pub fn lower_unsafety(_lctx: &LoweringContext, u: Unsafety) -> hir::Unsafety {
870 Unsafety::Unsafe => hir::Unsafety::Unsafe,
871 Unsafety::Normal => hir::Unsafety::Normal,
875 pub fn lower_constness(_lctx: &LoweringContext, c: Constness) -> hir::Constness {
877 Constness::Const => hir::Constness::Const,
878 Constness::NotConst => hir::Constness::NotConst,
882 pub fn lower_unop(_lctx: &LoweringContext, u: UnOp) -> hir::UnOp {
884 UnOp::Deref => hir::UnDeref,
885 UnOp::Not => hir::UnNot,
886 UnOp::Neg => hir::UnNeg,
890 pub fn lower_binop(_lctx: &LoweringContext, b: BinOp) -> hir::BinOp {
893 BinOpKind::Add => hir::BiAdd,
894 BinOpKind::Sub => hir::BiSub,
895 BinOpKind::Mul => hir::BiMul,
896 BinOpKind::Div => hir::BiDiv,
897 BinOpKind::Rem => hir::BiRem,
898 BinOpKind::And => hir::BiAnd,
899 BinOpKind::Or => hir::BiOr,
900 BinOpKind::BitXor => hir::BiBitXor,
901 BinOpKind::BitAnd => hir::BiBitAnd,
902 BinOpKind::BitOr => hir::BiBitOr,
903 BinOpKind::Shl => hir::BiShl,
904 BinOpKind::Shr => hir::BiShr,
905 BinOpKind::Eq => hir::BiEq,
906 BinOpKind::Lt => hir::BiLt,
907 BinOpKind::Le => hir::BiLe,
908 BinOpKind::Ne => hir::BiNe,
909 BinOpKind::Ge => hir::BiGe,
910 BinOpKind::Gt => hir::BiGt,
916 pub fn lower_pat(lctx: &LoweringContext, p: &Pat) -> P<hir::Pat> {
920 PatKind::Wild => hir::PatKind::Wild,
921 PatKind::Ident(ref binding_mode, pth1, ref sub) => {
922 hir::PatKind::Ident(lower_binding_mode(lctx, binding_mode),
923 respan(pth1.span, lower_ident(lctx, pth1.node)),
924 sub.as_ref().map(|x| lower_pat(lctx, x)))
926 PatKind::Lit(ref e) => hir::PatKind::Lit(lower_expr(lctx, e)),
927 PatKind::TupleStruct(ref pth, ref pats) => {
928 hir::PatKind::TupleStruct(lower_path(lctx, pth),
930 .map(|pats| pats.iter().map(|x| lower_pat(lctx, x)).collect()))
932 PatKind::Path(ref pth) => {
933 hir::PatKind::Path(lower_path(lctx, pth))
935 PatKind::QPath(ref qself, ref pth) => {
936 let qself = hir::QSelf {
937 ty: lower_ty(lctx, &qself.ty),
938 position: qself.position,
940 hir::PatKind::QPath(qself, lower_path(lctx, pth))
942 PatKind::Struct(ref pth, ref fields, etc) => {
943 let pth = lower_path(lctx, pth);
944 let fs = fields.iter()
948 node: hir::FieldPat {
949 name: f.node.ident.name,
950 pat: lower_pat(lctx, &f.node.pat),
951 is_shorthand: f.node.is_shorthand,
956 hir::PatKind::Struct(pth, fs, etc)
958 PatKind::Tup(ref elts) => {
959 hir::PatKind::Tup(elts.iter().map(|x| lower_pat(lctx, x)).collect())
961 PatKind::Box(ref inner) => hir::PatKind::Box(lower_pat(lctx, inner)),
962 PatKind::Ref(ref inner, mutbl) => {
963 hir::PatKind::Ref(lower_pat(lctx, inner), lower_mutability(lctx, mutbl))
965 PatKind::Range(ref e1, ref e2) => {
966 hir::PatKind::Range(lower_expr(lctx, e1), lower_expr(lctx, e2))
968 PatKind::Vec(ref before, ref slice, ref after) => {
969 hir::PatKind::Vec(before.iter().map(|x| lower_pat(lctx, x)).collect(),
970 slice.as_ref().map(|x| lower_pat(lctx, x)),
971 after.iter().map(|x| lower_pat(lctx, x)).collect())
973 PatKind::Mac(_) => panic!("Shouldn't exist here"),
979 pub fn lower_expr(lctx: &LoweringContext, e: &Expr) -> P<hir::Expr> {
984 // Eventually a desugaring for `box EXPR`
985 // (similar to the desugaring above for `in PLACE BLOCK`)
986 // should go here, desugaring
990 // let mut place = BoxPlace::make_place();
991 // let raw_place = Place::pointer(&mut place);
992 // let value = $value;
994 // ::std::ptr::write(raw_place, value);
995 // Boxed::finalize(place)
998 // But for now there are type-inference issues doing that.
999 ExprKind::Box(ref e) => {
1000 hir::ExprBox(lower_expr(lctx, e))
1003 // Desugar ExprBox: `in (PLACE) EXPR`
1004 ExprKind::InPlace(ref placer, ref value_expr) => {
1008 // let mut place = Placer::make_place(p);
1009 // let raw_place = Place::pointer(&mut place);
1011 // std::intrinsics::move_val_init(raw_place, pop_unsafe!( EXPR ));
1012 // InPlace::finalize(place)
1014 return cache_ids(lctx, e.id, |lctx| {
1015 let placer_expr = lower_expr(lctx, placer);
1016 let value_expr = lower_expr(lctx, value_expr);
1018 let placer_ident = lctx.str_to_ident("placer");
1019 let place_ident = lctx.str_to_ident("place");
1020 let p_ptr_ident = lctx.str_to_ident("p_ptr");
1022 let make_place = ["ops", "Placer", "make_place"];
1023 let place_pointer = ["ops", "Place", "pointer"];
1024 let move_val_init = ["intrinsics", "move_val_init"];
1025 let inplace_finalize = ["ops", "InPlace", "finalize"];
1027 let make_call = |lctx: &LoweringContext, p, args| {
1028 let path = core_path(lctx, e.span, p);
1029 let path = expr_path(lctx, path, None);
1030 expr_call(lctx, e.span, path, args, None)
1033 let mk_stmt_let = |lctx: &LoweringContext, bind, expr| {
1034 stmt_let(lctx, e.span, false, bind, expr, None)
1037 let mk_stmt_let_mut = |lctx: &LoweringContext, bind, expr| {
1038 stmt_let(lctx, e.span, true, bind, expr, None)
1041 // let placer = <placer_expr> ;
1043 let placer_expr = signal_block_expr(lctx,
1047 hir::PopUnstableBlock,
1049 mk_stmt_let(lctx, placer_ident, placer_expr)
1052 // let mut place = Placer::make_place(placer);
1054 let placer = expr_ident(lctx, e.span, placer_ident, None);
1055 let call = make_call(lctx, &make_place, hir_vec![placer]);
1056 mk_stmt_let_mut(lctx, place_ident, call)
1059 // let p_ptr = Place::pointer(&mut place);
1061 let agent = expr_ident(lctx, e.span, place_ident, None);
1062 let args = hir_vec![expr_mut_addr_of(lctx, e.span, agent, None)];
1063 let call = make_call(lctx, &place_pointer, args);
1064 mk_stmt_let(lctx, p_ptr_ident, call)
1067 // pop_unsafe!(EXPR));
1068 let pop_unsafe_expr = {
1069 let value_expr = signal_block_expr(lctx,
1073 hir::PopUnstableBlock,
1075 signal_block_expr(lctx,
1079 hir::PopUnsafeBlock(hir::CompilerGenerated), None)
1083 // std::intrinsics::move_val_init(raw_place, pop_unsafe!( EXPR ));
1084 // InPlace::finalize(place)
1087 let ptr = expr_ident(lctx, e.span, p_ptr_ident, None);
1088 let call_move_val_init =
1090 make_call(lctx, &move_val_init, hir_vec![ptr, pop_unsafe_expr]),
1092 let call_move_val_init = respan(e.span, call_move_val_init);
1094 let place = expr_ident(lctx, e.span, place_ident, None);
1095 let call = make_call(lctx, &inplace_finalize, hir_vec![place]);
1096 signal_block_expr(lctx,
1097 hir_vec![call_move_val_init],
1100 hir::PushUnsafeBlock(hir::CompilerGenerated), None)
1103 signal_block_expr(lctx,
1104 hir_vec![s1, s2, s3],
1107 hir::PushUnstableBlock,
1112 ExprKind::Vec(ref exprs) => {
1113 hir::ExprVec(exprs.iter().map(|x| lower_expr(lctx, x)).collect())
1115 ExprKind::Repeat(ref expr, ref count) => {
1116 let expr = lower_expr(lctx, expr);
1117 let count = lower_expr(lctx, count);
1118 hir::ExprRepeat(expr, count)
1120 ExprKind::Tup(ref elts) => {
1121 hir::ExprTup(elts.iter().map(|x| lower_expr(lctx, x)).collect())
1123 ExprKind::Call(ref f, ref args) => {
1124 let f = lower_expr(lctx, f);
1125 hir::ExprCall(f, args.iter().map(|x| lower_expr(lctx, x)).collect())
1127 ExprKind::MethodCall(i, ref tps, ref args) => {
1128 let tps = tps.iter().map(|x| lower_ty(lctx, x)).collect();
1129 let args = args.iter().map(|x| lower_expr(lctx, x)).collect();
1130 hir::ExprMethodCall(respan(i.span, i.node.name), tps, args)
1132 ExprKind::Binary(binop, ref lhs, ref rhs) => {
1133 let binop = lower_binop(lctx, binop);
1134 let lhs = lower_expr(lctx, lhs);
1135 let rhs = lower_expr(lctx, rhs);
1136 hir::ExprBinary(binop, lhs, rhs)
1138 ExprKind::Unary(op, ref ohs) => {
1139 let op = lower_unop(lctx, op);
1140 let ohs = lower_expr(lctx, ohs);
1141 hir::ExprUnary(op, ohs)
1143 ExprKind::Lit(ref l) => hir::ExprLit(P((**l).clone())),
1144 ExprKind::Cast(ref expr, ref ty) => {
1145 let expr = lower_expr(lctx, expr);
1146 hir::ExprCast(expr, lower_ty(lctx, ty))
1148 ExprKind::Type(ref expr, ref ty) => {
1149 let expr = lower_expr(lctx, expr);
1150 hir::ExprType(expr, lower_ty(lctx, ty))
1152 ExprKind::AddrOf(m, ref ohs) => {
1153 let m = lower_mutability(lctx, m);
1154 let ohs = lower_expr(lctx, ohs);
1155 hir::ExprAddrOf(m, ohs)
1157 // More complicated than you might expect because the else branch
1158 // might be `if let`.
1159 ExprKind::If(ref cond, ref blk, ref else_opt) => {
1160 let else_opt = else_opt.as_ref().map(|els| {
1162 ExprKind::IfLet(..) => {
1163 cache_ids(lctx, e.id, |lctx| {
1164 // wrap the if-let expr in a block
1165 let span = els.span;
1166 let els = lower_expr(lctx, els);
1167 let id = lctx.next_id();
1168 let blk = P(hir::Block {
1172 rules: hir::DefaultBlock,
1175 expr_block(lctx, blk, None)
1178 _ => lower_expr(lctx, els),
1182 hir::ExprIf(lower_expr(lctx, cond), lower_block(lctx, blk), else_opt)
1184 ExprKind::While(ref cond, ref body, opt_ident) => {
1185 hir::ExprWhile(lower_expr(lctx, cond), lower_block(lctx, body),
1186 opt_ident.map(|ident| lower_ident(lctx, ident)))
1188 ExprKind::Loop(ref body, opt_ident) => {
1189 hir::ExprLoop(lower_block(lctx, body),
1190 opt_ident.map(|ident| lower_ident(lctx, ident)))
1192 ExprKind::Match(ref expr, ref arms) => {
1193 hir::ExprMatch(lower_expr(lctx, expr),
1194 arms.iter().map(|x| lower_arm(lctx, x)).collect(),
1195 hir::MatchSource::Normal)
1197 ExprKind::Closure(capture_clause, ref decl, ref body) => {
1198 hir::ExprClosure(lower_capture_clause(lctx, capture_clause),
1199 lower_fn_decl(lctx, decl),
1200 lower_block(lctx, body))
1202 ExprKind::Block(ref blk) => hir::ExprBlock(lower_block(lctx, blk)),
1203 ExprKind::Assign(ref el, ref er) => {
1204 hir::ExprAssign(lower_expr(lctx, el), lower_expr(lctx, er))
1206 ExprKind::AssignOp(op, ref el, ref er) => {
1207 hir::ExprAssignOp(lower_binop(lctx, op),
1208 lower_expr(lctx, el),
1209 lower_expr(lctx, er))
1211 ExprKind::Field(ref el, ident) => {
1212 hir::ExprField(lower_expr(lctx, el), respan(ident.span, ident.node.name))
1214 ExprKind::TupField(ref el, ident) => {
1215 hir::ExprTupField(lower_expr(lctx, el), ident)
1217 ExprKind::Index(ref el, ref er) => {
1218 hir::ExprIndex(lower_expr(lctx, el), lower_expr(lctx, er))
1220 ExprKind::Range(ref e1, ref e2) => {
1221 hir::ExprRange(e1.as_ref().map(|x| lower_expr(lctx, x)),
1222 e2.as_ref().map(|x| lower_expr(lctx, x)))
1224 ExprKind::Path(ref qself, ref path) => {
1225 let hir_qself = qself.as_ref().map(|&QSelf { ref ty, position }| {
1227 ty: lower_ty(lctx, ty),
1231 hir::ExprPath(hir_qself, lower_path_full(lctx, path, qself.is_none()))
1233 ExprKind::Break(opt_ident) => hir::ExprBreak(opt_ident.map(|sp_ident| {
1234 respan(sp_ident.span, lower_ident(lctx, sp_ident.node))
1236 ExprKind::Again(opt_ident) => hir::ExprAgain(opt_ident.map(|sp_ident| {
1237 respan(sp_ident.span, lower_ident(lctx, sp_ident.node))
1239 ExprKind::Ret(ref e) => hir::ExprRet(e.as_ref().map(|x| lower_expr(lctx, x))),
1240 ExprKind::InlineAsm(InlineAsm {
1250 }) => hir::ExprInlineAsm(hir::InlineAsm {
1251 inputs: inputs.iter()
1252 .map(|&(ref c, ref input)| (c.clone(), lower_expr(lctx, input)))
1254 outputs: outputs.iter()
1256 hir::InlineAsmOutput {
1257 constraint: out.constraint.clone(),
1258 expr: lower_expr(lctx, &out.expr),
1260 is_indirect: out.is_indirect,
1265 asm_str_style: asm_str_style,
1266 clobbers: clobbers.clone().into(),
1268 alignstack: alignstack,
1272 ExprKind::Struct(ref path, ref fields, ref maybe_expr) => {
1273 hir::ExprStruct(lower_path(lctx, path),
1274 fields.iter().map(|x| lower_field(lctx, x)).collect(),
1275 maybe_expr.as_ref().map(|x| lower_expr(lctx, x)))
1277 ExprKind::Paren(ref ex) => {
1278 // merge attributes into the inner expression.
1279 return lower_expr(lctx, ex).map(|mut ex| {
1280 ex.attrs.update(|attrs| {
1281 attrs.prepend(e.attrs.clone())
1287 // Desugar ExprIfLet
1288 // From: `if let <pat> = <sub_expr> <body> [<else_opt>]`
1289 ExprKind::IfLet(ref pat, ref sub_expr, ref body, ref else_opt) => {
1292 // match <sub_expr> {
1294 // [_ if <else_opt_if_cond> => <else_opt_if_body>,]
1295 // _ => [<else_opt> | ()]
1298 return cache_ids(lctx, e.id, |lctx| {
1299 // `<pat> => <body>`
1301 let body = lower_block(lctx, body);
1302 let body_expr = expr_block(lctx, body, None);
1303 arm(hir_vec![lower_pat(lctx, pat)], body_expr)
1306 // `[_ if <else_opt_if_cond> => <else_opt_if_body>,]`
1307 let mut else_opt = else_opt.as_ref().map(|e| lower_expr(lctx, e));
1308 let else_if_arms = {
1309 let mut arms = vec![];
1311 let else_opt_continue = else_opt.and_then(|els| {
1312 els.and_then(|els| {
1315 hir::ExprIf(cond, then, else_opt) => {
1316 let pat_under = pat_wild(lctx, e.span);
1317 arms.push(hir::Arm {
1319 pats: hir_vec![pat_under],
1321 body: expr_block(lctx, then, None),
1323 else_opt.map(|else_opt| (else_opt, true))
1325 _ => Some((P(els), false)),
1329 match else_opt_continue {
1330 Some((e, true)) => {
1333 Some((e, false)) => {
1346 let contains_else_clause = else_opt.is_some();
1348 // `_ => [<else_opt> | ()]`
1350 let pat_under = pat_wild(lctx, e.span);
1352 else_opt.unwrap_or_else(
1353 || expr_tuple(lctx, e.span, hir_vec![], None));
1354 arm(hir_vec![pat_under], else_expr)
1357 let mut arms = Vec::with_capacity(else_if_arms.len() + 2);
1359 arms.extend(else_if_arms);
1360 arms.push(else_arm);
1362 let sub_expr = lower_expr(lctx, sub_expr);
1363 // add attributes to the outer returned expr node
1366 hir::ExprMatch(sub_expr,
1368 hir::MatchSource::IfLetDesugar {
1369 contains_else_clause: contains_else_clause,
1375 // Desugar ExprWhileLet
1376 // From: `[opt_ident]: while let <pat> = <sub_expr> <body>`
1377 ExprKind::WhileLet(ref pat, ref sub_expr, ref body, opt_ident) => {
1380 // [opt_ident]: loop {
1381 // match <sub_expr> {
1387 return cache_ids(lctx, e.id, |lctx| {
1388 // `<pat> => <body>`
1390 let body = lower_block(lctx, body);
1391 let body_expr = expr_block(lctx, body, None);
1392 arm(hir_vec![lower_pat(lctx, pat)], body_expr)
1397 let pat_under = pat_wild(lctx, e.span);
1398 let break_expr = expr_break(lctx, e.span, None);
1399 arm(hir_vec![pat_under], break_expr)
1402 // `match <sub_expr> { ... }`
1403 let arms = hir_vec![pat_arm, break_arm];
1404 let sub_expr = lower_expr(lctx, sub_expr);
1405 let match_expr = expr(lctx,
1407 hir::ExprMatch(sub_expr,
1409 hir::MatchSource::WhileLetDesugar),
1412 // `[opt_ident]: loop { ... }`
1413 let loop_block = block_expr(lctx, match_expr);
1414 let loop_expr = hir::ExprLoop(loop_block,
1415 opt_ident.map(|ident| lower_ident(lctx, ident)));
1416 // add attributes to the outer returned expr node
1417 expr(lctx, e.span, loop_expr, e.attrs.clone())
1421 // Desugar ExprForLoop
1422 // From: `[opt_ident]: for <pat> in <head> <body>`
1423 ExprKind::ForLoop(ref pat, ref head, ref body, opt_ident) => {
1427 // let result = match ::std::iter::IntoIterator::into_iter(<head>) {
1429 // [opt_ident]: loop {
1430 // match ::std::iter::Iterator::next(&mut iter) {
1431 // ::std::option::Option::Some(<pat>) => <body>,
1432 // ::std::option::Option::None => break
1440 return cache_ids(lctx, e.id, |lctx| {
1442 let head = lower_expr(lctx, head);
1444 let iter = lctx.str_to_ident("iter");
1446 // `::std::option::Option::Some(<pat>) => <body>`
1448 let body_block = lower_block(lctx, body);
1449 let body_span = body_block.span;
1450 let body_expr = P(hir::Expr {
1452 node: hir::ExprBlock(body_block),
1456 let pat = lower_pat(lctx, pat);
1457 let some_pat = pat_some(lctx, e.span, pat);
1459 arm(hir_vec![some_pat], body_expr)
1462 // `::std::option::Option::None => break`
1464 let break_expr = expr_break(lctx, e.span, None);
1466 arm(hir_vec![pat_none(lctx, e.span)], break_expr)
1469 // `match ::std::iter::Iterator::next(&mut iter) { ... }`
1472 let strs = std_path(lctx, &["iter", "Iterator", "next"]);
1474 path_global(e.span, strs)
1476 let iter = expr_ident(lctx, e.span, iter, None);
1477 let ref_mut_iter = expr_mut_addr_of(lctx, e.span, iter, None);
1478 let next_path = expr_path(lctx, next_path, None);
1479 let next_expr = expr_call(lctx,
1482 hir_vec![ref_mut_iter],
1484 let arms = hir_vec![pat_arm, break_arm];
1488 hir::ExprMatch(next_expr, arms, hir::MatchSource::ForLoopDesugar),
1492 // `[opt_ident]: loop { ... }`
1493 let loop_block = block_expr(lctx, match_expr);
1494 let loop_expr = hir::ExprLoop(loop_block,
1495 opt_ident.map(|ident| lower_ident(lctx, ident)));
1496 let loop_expr = expr(lctx, e.span, loop_expr, None);
1498 // `mut iter => { ... }`
1500 let iter_pat = pat_ident_binding_mode(lctx,
1503 hir::BindByValue(hir::MutMutable));
1504 arm(hir_vec![iter_pat], loop_expr)
1507 // `match ::std::iter::IntoIterator::into_iter(<head>) { ... }`
1508 let into_iter_expr = {
1509 let into_iter_path = {
1510 let strs = std_path(lctx, &["iter", "IntoIterator", "into_iter"]);
1512 path_global(e.span, strs)
1515 let into_iter = expr_path(lctx, into_iter_path, None);
1516 expr_call(lctx, e.span, into_iter, hir_vec![head], None)
1519 let match_expr = expr_match(lctx,
1523 hir::MatchSource::ForLoopDesugar,
1526 // `{ let _result = ...; _result }`
1527 // underscore prevents an unused_variables lint if the head diverges
1528 let result_ident = lctx.str_to_ident("_result");
1529 let let_stmt = stmt_let(lctx, e.span, false, result_ident, match_expr, None);
1530 let result = expr_ident(lctx, e.span, result_ident, None);
1531 let block = block_all(lctx, e.span, hir_vec![let_stmt], Some(result));
1532 // add the attributes to the outer returned expr node
1533 expr_block(lctx, block, e.attrs.clone())
1537 ExprKind::Mac(_) => panic!("Shouldn't exist here"),
1540 attrs: e.attrs.clone(),
1544 pub fn lower_stmt(lctx: &LoweringContext, s: &Stmt) -> hir::Stmt {
1546 StmtKind::Decl(ref d, id) => {
1548 node: hir::StmtDecl(lower_decl(lctx, d), id),
1552 StmtKind::Expr(ref e, id) => {
1554 node: hir::StmtExpr(lower_expr(lctx, e), id),
1558 StmtKind::Semi(ref e, id) => {
1560 node: hir::StmtSemi(lower_expr(lctx, e), id),
1564 StmtKind::Mac(..) => panic!("Shouldn't exist here"),
1568 pub fn lower_capture_clause(_lctx: &LoweringContext, c: CaptureBy) -> hir::CaptureClause {
1570 CaptureBy::Value => hir::CaptureByValue,
1571 CaptureBy::Ref => hir::CaptureByRef,
1575 pub fn lower_visibility(_lctx: &LoweringContext, v: Visibility) -> hir::Visibility {
1577 Visibility::Public => hir::Public,
1578 Visibility::Inherited => hir::Inherited,
1582 pub fn lower_block_check_mode(lctx: &LoweringContext, b: &BlockCheckMode) -> hir::BlockCheckMode {
1584 BlockCheckMode::Default => hir::DefaultBlock,
1585 BlockCheckMode::Unsafe(u) => hir::UnsafeBlock(lower_unsafe_source(lctx, u)),
1589 pub fn lower_binding_mode(lctx: &LoweringContext, b: &BindingMode) -> hir::BindingMode {
1591 BindingMode::ByRef(m) => hir::BindByRef(lower_mutability(lctx, m)),
1592 BindingMode::ByValue(m) => hir::BindByValue(lower_mutability(lctx, m)),
1596 pub fn lower_unsafe_source(_lctx: &LoweringContext, u: UnsafeSource) -> hir::UnsafeSource {
1598 CompilerGenerated => hir::CompilerGenerated,
1599 UserProvided => hir::UserProvided,
1603 pub fn lower_impl_polarity(_lctx: &LoweringContext, i: ImplPolarity) -> hir::ImplPolarity {
1605 ImplPolarity::Positive => hir::ImplPolarity::Positive,
1606 ImplPolarity::Negative => hir::ImplPolarity::Negative,
1610 pub fn lower_trait_bound_modifier(_lctx: &LoweringContext,
1611 f: TraitBoundModifier)
1612 -> hir::TraitBoundModifier {
1614 TraitBoundModifier::None => hir::TraitBoundModifier::None,
1615 TraitBoundModifier::Maybe => hir::TraitBoundModifier::Maybe,
1619 // Helper methods for building HIR.
1621 fn arm(pats: hir::HirVec<P<hir::Pat>>, expr: P<hir::Expr>) -> hir::Arm {
1630 fn expr_break(lctx: &LoweringContext, span: Span,
1631 attrs: ThinAttributes) -> P<hir::Expr> {
1632 expr(lctx, span, hir::ExprBreak(None), attrs)
1635 fn expr_call(lctx: &LoweringContext,
1638 args: hir::HirVec<P<hir::Expr>>,
1639 attrs: ThinAttributes)
1641 expr(lctx, span, hir::ExprCall(e, args), attrs)
1644 fn expr_ident(lctx: &LoweringContext, span: Span, id: hir::Ident,
1645 attrs: ThinAttributes) -> P<hir::Expr> {
1646 expr_path(lctx, path_ident(span, id), attrs)
1649 fn expr_mut_addr_of(lctx: &LoweringContext, span: Span, e: P<hir::Expr>,
1650 attrs: ThinAttributes) -> P<hir::Expr> {
1651 expr(lctx, span, hir::ExprAddrOf(hir::MutMutable, e), attrs)
1654 fn expr_path(lctx: &LoweringContext, path: hir::Path,
1655 attrs: ThinAttributes) -> P<hir::Expr> {
1656 expr(lctx, path.span, hir::ExprPath(None, path), attrs)
1659 fn expr_match(lctx: &LoweringContext,
1662 arms: hir::HirVec<hir::Arm>,
1663 source: hir::MatchSource,
1664 attrs: ThinAttributes)
1666 expr(lctx, span, hir::ExprMatch(arg, arms, source), attrs)
1669 fn expr_block(lctx: &LoweringContext, b: P<hir::Block>,
1670 attrs: ThinAttributes) -> P<hir::Expr> {
1671 expr(lctx, b.span, hir::ExprBlock(b), attrs)
1674 fn expr_tuple(lctx: &LoweringContext, sp: Span, exprs: hir::HirVec<P<hir::Expr>>,
1675 attrs: ThinAttributes) -> P<hir::Expr> {
1676 expr(lctx, sp, hir::ExprTup(exprs), attrs)
1679 fn expr(lctx: &LoweringContext, span: Span, node: hir::Expr_,
1680 attrs: ThinAttributes) -> P<hir::Expr> {
1689 fn stmt_let(lctx: &LoweringContext,
1694 attrs: ThinAttributes)
1696 let pat = if mutbl {
1697 pat_ident_binding_mode(lctx, sp, ident, hir::BindByValue(hir::MutMutable))
1699 pat_ident(lctx, sp, ident)
1701 let local = P(hir::Local {
1709 let decl = respan(sp, hir::DeclLocal(local));
1710 respan(sp, hir::StmtDecl(P(decl), lctx.next_id()))
1713 fn block_expr(lctx: &LoweringContext, expr: P<hir::Expr>) -> P<hir::Block> {
1714 block_all(lctx, expr.span, hir::HirVec::new(), Some(expr))
1717 fn block_all(lctx: &LoweringContext,
1719 stmts: hir::HirVec<hir::Stmt>,
1720 expr: Option<P<hir::Expr>>)
1726 rules: hir::DefaultBlock,
1731 fn pat_some(lctx: &LoweringContext, span: Span, pat: P<hir::Pat>) -> P<hir::Pat> {
1732 let some = std_path(lctx, &["option", "Option", "Some"]);
1733 let path = path_global(span, some);
1734 pat_enum(lctx, span, path, hir_vec![pat])
1737 fn pat_none(lctx: &LoweringContext, span: Span) -> P<hir::Pat> {
1738 let none = std_path(lctx, &["option", "Option", "None"]);
1739 let path = path_global(span, none);
1740 pat_enum(lctx, span, path, hir_vec![])
1743 fn pat_enum(lctx: &LoweringContext,
1746 subpats: hir::HirVec<P<hir::Pat>>)
1748 let pt = if subpats.is_empty() {
1749 hir::PatKind::Path(path)
1751 hir::PatKind::TupleStruct(path, Some(subpats))
1756 fn pat_ident(lctx: &LoweringContext, span: Span, ident: hir::Ident) -> P<hir::Pat> {
1757 pat_ident_binding_mode(lctx, span, ident, hir::BindByValue(hir::MutImmutable))
1760 fn pat_ident_binding_mode(lctx: &LoweringContext,
1763 bm: hir::BindingMode)
1765 let pat_ident = hir::PatKind::Ident(bm,
1771 pat(lctx, span, pat_ident)
1774 fn pat_wild(lctx: &LoweringContext, span: Span) -> P<hir::Pat> {
1775 pat(lctx, span, hir::PatKind::Wild)
1778 fn pat(lctx: &LoweringContext, span: Span, pat: hir::PatKind) -> P<hir::Pat> {
1786 fn path_ident(span: Span, id: hir::Ident) -> hir::Path {
1787 path(span, vec![id])
1790 fn path(span: Span, strs: Vec<hir::Ident>) -> hir::Path {
1791 path_all(span, false, strs, hir::HirVec::new(), hir::HirVec::new(), hir::HirVec::new())
1794 fn path_global(span: Span, strs: Vec<hir::Ident>) -> hir::Path {
1795 path_all(span, true, strs, hir::HirVec::new(), hir::HirVec::new(), hir::HirVec::new())
1798 fn path_all(sp: Span,
1800 mut idents: Vec<hir::Ident>,
1801 lifetimes: hir::HirVec<hir::Lifetime>,
1802 types: hir::HirVec<P<hir::Ty>>,
1803 bindings: hir::HirVec<hir::TypeBinding>)
1805 let last_identifier = idents.pop().unwrap();
1806 let mut segments: Vec<hir::PathSegment> = idents.into_iter()
1810 parameters: hir::PathParameters::none(),
1814 segments.push(hir::PathSegment {
1815 identifier: last_identifier,
1816 parameters: hir::AngleBracketedParameters(hir::AngleBracketedParameterData {
1817 lifetimes: lifetimes,
1825 segments: segments.into(),
1829 fn std_path(lctx: &LoweringContext, components: &[&str]) -> Vec<hir::Ident> {
1830 let mut v = Vec::new();
1831 if let Some(s) = lctx.crate_root {
1832 v.push(hir::Ident::from_name(token::intern(s)));
1834 v.extend(components.iter().map(|s| hir::Ident::from_name(token::intern(s))));
1838 // Given suffix ["b","c","d"], returns path `::std::b::c::d` when
1839 // `fld.cx.use_std`, and `::core::b::c::d` otherwise.
1840 fn core_path(lctx: &LoweringContext, span: Span, components: &[&str]) -> hir::Path {
1841 let idents = std_path(lctx, components);
1842 path_global(span, idents)
1845 fn signal_block_expr(lctx: &LoweringContext,
1846 stmts: hir::HirVec<hir::Stmt>,
1849 rule: hir::BlockCheckMode,
1850 attrs: ThinAttributes)
1852 let id = lctx.next_id();
1869 use syntax::ast::{self, NodeId, NodeIdAssigner};
1870 use syntax::{parse, codemap};
1871 use syntax::fold::Folder;
1872 use std::cell::Cell;
1874 struct MockAssigner {
1875 next_id: Cell<NodeId>,
1879 fn new() -> MockAssigner {
1880 MockAssigner { next_id: Cell::new(0) }
1885 fn call_site(&self) -> codemap::Span;
1886 fn cfg(&self) -> ast::CrateConfig;
1887 fn ident_of(&self, st: &str) -> ast::Ident;
1888 fn name_of(&self, st: &str) -> ast::Name;
1889 fn parse_sess(&self) -> &parse::ParseSess;
1892 impl FakeExtCtxt for parse::ParseSess {
1893 fn call_site(&self) -> codemap::Span {
1895 lo: codemap::BytePos(0),
1896 hi: codemap::BytePos(0),
1897 expn_id: codemap::NO_EXPANSION,
1900 fn cfg(&self) -> ast::CrateConfig {
1903 fn ident_of(&self, st: &str) -> ast::Ident {
1904 parse::token::str_to_ident(st)
1906 fn name_of(&self, st: &str) -> ast::Name {
1907 parse::token::intern(st)
1909 fn parse_sess(&self) -> &parse::ParseSess {
1914 impl NodeIdAssigner for MockAssigner {
1915 fn next_node_id(&self) -> NodeId {
1916 let result = self.next_id.get();
1917 self.next_id.set(result + 1);
1921 fn peek_node_id(&self) -> NodeId {
1926 impl Folder for MockAssigner {
1927 fn new_id(&mut self, old_id: NodeId) -> NodeId {
1928 assert_eq!(old_id, ast::DUMMY_NODE_ID);
1934 fn test_preserves_ids() {
1935 let cx = parse::ParseSess::new();
1936 let mut assigner = MockAssigner::new();
1938 let ast_if_let = quote_expr!(&cx,
1939 if let Some(foo) = baz {
1942 let ast_if_let = assigner.fold_expr(ast_if_let);
1943 let ast_while_let = quote_expr!(&cx,
1944 while let Some(foo) = baz {
1947 let ast_while_let = assigner.fold_expr(ast_while_let);
1948 let ast_for = quote_expr!(&cx,
1954 let ast_for = assigner.fold_expr(ast_for);
1955 let ast_in = quote_expr!(&cx, in HEAP { foo() });
1956 let ast_in = assigner.fold_expr(ast_in);
1958 let lctx = LoweringContext::new(&assigner, None);
1959 let hir1 = lower_expr(&lctx, &ast_if_let);
1960 let hir2 = lower_expr(&lctx, &ast_if_let);
1961 assert!(hir1 == hir2);
1963 let hir1 = lower_expr(&lctx, &ast_while_let);
1964 let hir2 = lower_expr(&lctx, &ast_while_let);
1965 assert!(hir1 == hir2);
1967 let hir1 = lower_expr(&lctx, &ast_for);
1968 let hir2 = lower_expr(&lctx, &ast_for);
1969 assert!(hir1 == hir2);
1971 let hir1 = lower_expr(&lctx, &ast_in);
1972 let hir2 = lower_expr(&lctx, &ast_in);
1973 assert!(hir1 == hir2);