X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=src%2Flibrustc_front%2Flowering.rs;h=bd5f7cf3c626eba2c81dba90444a1e7f9f1198fb;hb=ea47c2b6b349d7f252a6a734ced8204e6ef70546;hp=c8f5f89b669109142e1f2f485e214475c727d7fa;hpb=20083c1e1f6916eb79e3d967c1c9ab63342c71ae;p=rust.git diff --git a/src/librustc_front/lowering.rs b/src/librustc_front/lowering.rs index c8f5f89b669..bd5f7cf3c62 100644 --- a/src/librustc_front/lowering.rs +++ b/src/librustc_front/lowering.rs @@ -8,10 +8,63 @@ // option. This file may not be copied, modified, or distributed // except according to those terms. -// Lowers the AST to the HIR +// Lowers the AST to the HIR. +// +// Since the AST and HIR are fairly similar, this is mostly a simple procedure, +// much like a fold. Where lowering involves a bit more work things get more +// interesting and there are some invariants you should know about. These mostly +// concern spans and ids. +// +// Spans are assigned to AST nodes during parsing and then are modified during +// expansion to indicate the origin of a node and the process it went through +// being expanded. Ids are assigned to AST nodes just before lowering. +// +// For the simpler lowering steps, ids and spans should be preserved. Unlike +// expansion we do not preserve the process of lowering in the spans, so spans +// should not be modified here. When creating a new node (as opposed to +// 'folding' an existing one), then you create a new id using `next_id()`. +// +// You must ensure that ids are unique. That means that you should only use the +// id from an AST node in a single HIR node (you can assume that AST node ids +// are unique). Every new node must have a unique id. Avoid cloning HIR nodes. +// If you do, you must then set the new node's id to a fresh one. +// +// Lowering must be reproducable (the compiler only lowers once, but tools and +// custom lints may lower an AST node to a HIR node to interact with the +// compiler). The most interesting bit of this is ids - if you lower an AST node +// and create new HIR nodes with fresh ids, when re-lowering the same node, you +// must ensure you get the same ids! To do this, we keep track of the next id +// when we translate a node which requires new ids. By checking this cache and +// using node ids starting with the cached id, we ensure ids are reproducible. +// To use this system, you just need to hold on to a CachedIdSetter object +// whilst lowering. This is an RAII object that takes care of setting and +// restoring the cached id, etc. +// +// This whole system relies on node ids being incremented one at a time and +// all increments being for lowering. This means that you should not call any +// non-lowering function which will use new node ids. +// +// We must also cache gensym'ed Idents to ensure that we get the same Ident +// every time we lower a node with gensym'ed names. One consequence of this is +// that you can only gensym a name once in a lowering (you don't need to worry +// about nested lowering though). That's because we cache based on the name and +// the currently cached node id, which is unique per lowered node. +// +// Spans are used for error messages and for tools to map semantics back to +// source code. It is therefore not as important with spans as ids to be strict +// about use (you can't break the compiler by screwing up a span). Obviously, a +// HIR node can only have a single span. But multiple nodes can have the same +// span and spans don't need to be kept in order, etc. Where code is preserved +// by lowering, it should have the same span as in the AST. Where HIR nodes are +// new it is probably best to give a span for the whole AST node being lowered. +// All nodes should have real spans, don't use dummy spans. Tools are likely to +// get confused if the spans from leaf AST nodes occur in multiple places +// in the HIR, especially for multiple identifiers. use hir; +use std::collections::HashMap; + use syntax::ast::*; use syntax::ptr::P; use syntax::codemap::{respan, Spanned, Span}; @@ -19,32 +72,69 @@ use syntax::parse::token::{self, str_to_ident}; use syntax::std_inject; -pub struct LoweringContext<'a, 'hir> { - // TODO - foo: &'hir i32, - id_assigner: &'a NodeIdAssigner, - crate_root: Option<&'static str>, -} +use std::cell::{Cell, RefCell}; -impl<'a, 'hir> LoweringContext<'a, 'hir> { - pub fn new(foo: &'hir i32, id_assigner: &'a NodeIdAssigner, c: &Crate) -> LoweringContext<'a, 'hir> { - let crate_root = if std_inject::no_core(c) { - None - } else if std_inject::no_std(c) { - Some("core") - } else { - Some("std") - }; +pub struct LoweringContext<'a> { + crate_root: Option<&'static str>, + // Map AST ids to ids used for expanded nodes. + id_cache: RefCell>, + // Use if there are no cached ids for the current node. + id_assigner: &'a NodeIdAssigner, + // 0 == no cached id. Must be incremented to align with previous id + // incrementing. + cached_id: Cell, + // Keep track of gensym'ed idents. + gensym_cache: RefCell>, + // A copy of cached_id, but is also set to an id while it is being cached. + gensym_key: Cell, +} + +impl<'a, 'hir> LoweringContext<'a> { + pub fn new(id_assigner: &'a NodeIdAssigner, c: Option<&Crate>) -> LoweringContext<'a> { + let crate_root = c.and_then(|c| { + if std_inject::no_core(c) { + None + } else if std_inject::no_std(c) { + Some("core") + } else { + Some("std") + } + }); LoweringContext { - foo: foo, - id_assigner: id_assigner, crate_root: crate_root, + id_cache: RefCell::new(HashMap::new()), + id_assigner: id_assigner, + cached_id: Cell::new(0), + gensym_cache: RefCell::new(HashMap::new()), + gensym_key: Cell::new(0), } } fn next_id(&self) -> NodeId { - self.id_assigner.next_node_id() + let cached = self.cached_id.get(); + if cached == 0 { + return self.id_assigner.next_node_id() + } + + self.cached_id.set(cached + 1); + cached + } + + fn str_to_ident(&self, s: &'static str) -> Ident { + let cached_id = self.gensym_key.get(); + if cached_id == 0 { + return token::gensym_ident(s); + } + + let cached = self.gensym_cache.borrow().contains_key(&(cached_id, s)); + if cached { + self.gensym_cache.borrow()[&(cached_id, s)] + } else { + let result = token::gensym_ident(s); + self.gensym_cache.borrow_mut().insert((cached_id, s), result); + result + } } } @@ -59,24 +149,26 @@ pub fn lower_view_path(_lctx: &LoweringContext, view_path: &ViewPath) -> P { hir::ViewPathList(lower_path(_lctx, path), - path_list_idents.iter().map(|path_list_ident| { - Spanned { - node: match path_list_ident.node { - PathListIdent { id, name, rename } => - hir::PathListIdent { - id: id, - name: name.name, - rename: rename.map(|x| x.name), - }, - PathListMod { id, rename } => - hir::PathListMod { - id: id, - rename: rename.map(|x| x.name) - } - }, - span: path_list_ident.span - } - }).collect()) + path_list_idents.iter() + .map(|path_list_ident| { + Spanned { + node: match path_list_ident.node { + PathListIdent { id, name, rename } => + hir::PathListIdent { + id: id, + name: name.name, + rename: rename.map(|x| x.name), + }, + PathListMod { id, rename } => + hir::PathListMod { + id: id, + rename: rename.map(|x| x.name), + }, + }, + span: path_list_ident.span, + } + }) + .collect()) } }, span: view_path.span, @@ -96,17 +188,22 @@ pub fn lower_decl(_lctx: &LoweringContext, d: &Decl) -> P { match d.node { DeclLocal(ref l) => P(Spanned { node: hir::DeclLocal(lower_local(_lctx, l)), - span: d.span + span: d.span, }), DeclItem(ref it) => P(Spanned { node: hir::DeclItem(lower_item(_lctx, it)), - span: d.span + span: d.span, }), } } pub fn lower_ty_binding(_lctx: &LoweringContext, b: &TypeBinding) -> P { - P(hir::TypeBinding { id: b.id, name: b.ident.name, ty: lower_ty(_lctx, &b.ty), span: b.span }) + P(hir::TypeBinding { + id: b.id, + name: b.ident.name, + ty: lower_ty(_lctx, &b.ty), + span: b.span, + }) } pub fn lower_ty(_lctx: &LoweringContext, t: &Ty) -> P { @@ -117,7 +214,8 @@ pub fn lower_ty(_lctx: &LoweringContext, t: &Ty) -> P { TyVec(ref ty) => hir::TyVec(lower_ty(_lctx, ty)), TyPtr(ref mt) => hir::TyPtr(lower_mt(_lctx, mt)), TyRptr(ref region, ref mt) => { - hir::TyRptr(lower_opt_lifetime(_lctx, region), lower_mt(_lctx, mt)) + hir::TyRptr(lower_opt_lifetime(_lctx, region), + lower_mt(_lctx, mt)) } TyBareFn(ref f) => { hir::TyBareFn(P(hir::BareFnTy { @@ -139,8 +237,7 @@ pub fn lower_ty(_lctx: &LoweringContext, t: &Ty) -> P { hir::TyPath(qself, lower_path(_lctx, path)) } TyObjectSum(ref ty, ref bounds) => { - hir::TyObjectSum(lower_ty(_lctx, ty), - lower_bounds(_lctx, bounds)) + hir::TyObjectSum(lower_ty(_lctx, ty), lower_bounds(_lctx, bounds)) } TyFixedLengthVec(ref ty, ref e) => { hir::TyFixedLengthVec(lower_ty(_lctx, ty), lower_expr(_lctx, e)) @@ -170,13 +267,13 @@ pub fn lower_variant(_lctx: &LoweringContext, v: &Variant) -> P { id: v.node.id, name: v.node.name.name, attrs: v.node.attrs.clone(), - kind: match v.node.kind { - TupleVariantKind(ref variant_args) => { - hir::TupleVariantKind(variant_args.iter().map(|ref x| - lower_variant_arg(_lctx, x)).collect()) - } - StructVariantKind(ref struct_def) => { - hir::StructVariantKind(lower_struct_def(_lctx, struct_def)) + kind: { + if v.node.def.ctor_id.is_none() { + hir::StructVariantKind(lower_struct_def(_lctx, &v.node.def)) + } else { + hir::TupleVariantKind(v.node.def.fields.iter().map(|ref field| { + hir::VariantArg { id: field.node.id, ty: lower_ty(_lctx, &field.node.ty) } + }).collect()) } }, disr_expr: v.node.disr_expr.as_ref().map(|e| lower_expr(_lctx, e)), @@ -188,11 +285,15 @@ pub fn lower_variant(_lctx: &LoweringContext, v: &Variant) -> P { pub fn lower_path(_lctx: &LoweringContext, p: &Path) -> hir::Path { hir::Path { global: p.global, - segments: p.segments.iter().map(|&PathSegment {identifier, ref parameters}| - hir::PathSegment { - identifier: identifier, - parameters: lower_path_parameters(_lctx, parameters), - }).collect(), + segments: p.segments + .iter() + .map(|&PathSegment { identifier, ref parameters }| { + hir::PathSegment { + identifier: identifier, + parameters: lower_path_parameters(_lctx, parameters), + } + }) + .collect(), span: p.span, } } @@ -232,12 +333,12 @@ pub fn lower_parenthesized_parameter_data(_lctx: &LoweringContext, pub fn lower_local(_lctx: &LoweringContext, l: &Local) -> P { P(hir::Local { - id: l.id, - ty: l.ty.as_ref().map(|t| lower_ty(_lctx, t)), - pat: lower_pat(_lctx, &l.pat), - init: l.init.as_ref().map(|e| lower_expr(_lctx, e)), - span: l.span, - }) + id: l.id, + ty: l.ty.as_ref().map(|t| lower_ty(_lctx, t)), + pat: lower_pat(_lctx, &l.pat), + init: l.init.as_ref().map(|e| lower_expr(_lctx, e)), + span: l.span, + }) } pub fn lower_explicit_self_underscore(_lctx: &LoweringContext, @@ -265,11 +366,18 @@ pub fn lower_mutability(_lctx: &LoweringContext, m: Mutability) -> hir::Mutabili } pub fn lower_explicit_self(_lctx: &LoweringContext, s: &ExplicitSelf) -> hir::ExplicitSelf { - Spanned { node: lower_explicit_self_underscore(_lctx, &s.node), span: s.span } + Spanned { + node: lower_explicit_self_underscore(_lctx, &s.node), + span: s.span, + } } pub fn lower_arg(_lctx: &LoweringContext, arg: &Arg) -> hir::Arg { - hir::Arg { id: arg.id, pat: lower_pat(_lctx, &arg.pat), ty: lower_ty(_lctx, &arg.ty) } + hir::Arg { + id: arg.id, + pat: lower_pat(_lctx, &arg.pat), + ty: lower_ty(_lctx, &arg.ty), + } } pub fn lower_fn_decl(_lctx: &LoweringContext, decl: &FnDecl) -> P { @@ -313,13 +421,17 @@ pub fn lower_ty_params(_lctx: &LoweringContext, } pub fn lower_lifetime(_lctx: &LoweringContext, l: &Lifetime) -> hir::Lifetime { - hir::Lifetime { id: l.id, name: l.name, span: l.span } + hir::Lifetime { + id: l.id, + name: l.name, + span: l.span, + } } pub fn lower_lifetime_def(_lctx: &LoweringContext, l: &LifetimeDef) -> hir::LifetimeDef { hir::LifetimeDef { lifetime: lower_lifetime(_lctx, &l.lifetime), - bounds: lower_lifetimes(_lctx, &l.bounds) + bounds: lower_lifetimes(_lctx, &l.bounds), } } @@ -350,8 +462,10 @@ pub fn lower_generics(_lctx: &LoweringContext, g: &Generics) -> hir::Generics { pub fn lower_where_clause(_lctx: &LoweringContext, wc: &WhereClause) -> hir::WhereClause { hir::WhereClause { id: wc.id, - predicates: wc.predicates.iter().map(|predicate| - lower_where_predicate(_lctx, predicate)).collect(), + predicates: wc.predicates + .iter() + .map(|predicate| lower_where_predicate(_lctx, predicate)) + .collect(), } } @@ -367,7 +481,7 @@ pub fn lower_where_predicate(_lctx: &LoweringContext, bound_lifetimes: lower_lifetime_defs(_lctx, bound_lifetimes), bounded_ty: lower_ty(_lctx, bounded_ty), bounds: bounds.iter().map(|x| lower_ty_param_bound(_lctx, x)).collect(), - span: span + span: span, }) } WherePredicate::RegionPredicate(WhereRegionPredicate{ ref lifetime, @@ -376,7 +490,7 @@ pub fn lower_where_predicate(_lctx: &LoweringContext, hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate { span: span, lifetime: lower_lifetime(_lctx, lifetime), - bounds: bounds.iter().map(|bound| lower_lifetime(_lctx, bound)).collect() + bounds: bounds.iter().map(|bound| lower_lifetime(_lctx, bound)).collect(), }) } WherePredicate::EqPredicate(WhereEqPredicate{ id, @@ -386,8 +500,8 @@ pub fn lower_where_predicate(_lctx: &LoweringContext, hir::WherePredicate::EqPredicate(hir::WhereEqPredicate { id: id, path: lower_path(_lctx, path), - ty:lower_ty(_lctx, ty), - span: span + ty: lower_ty(_lctx, ty), + span: span, }) } } @@ -401,7 +515,10 @@ pub fn lower_struct_def(_lctx: &LoweringContext, sd: &StructDef) -> P hir::TraitRef { - hir::TraitRef { path: lower_path(_lctx, &p.path), ref_id: p.ref_id } + hir::TraitRef { + path: lower_path(_lctx, &p.path), + ref_id: p.ref_id, + } } pub fn lower_poly_trait_ref(_lctx: &LoweringContext, p: &PolyTraitRef) -> hir::PolyTraitRef { @@ -427,15 +544,20 @@ pub fn lower_struct_field(_lctx: &LoweringContext, f: &StructField) -> hir::Stru pub fn lower_field(_lctx: &LoweringContext, f: &Field) -> hir::Field { hir::Field { name: respan(f.ident.span, f.ident.node.name), - expr: lower_expr(_lctx, &f.expr), span: f.span + expr: lower_expr(_lctx, &f.expr), + span: f.span, } } pub fn lower_mt(_lctx: &LoweringContext, mt: &MutTy) -> hir::MutTy { - hir::MutTy { ty: lower_ty(_lctx, &mt.ty), mutbl: lower_mutability(_lctx, mt.mutbl) } + hir::MutTy { + ty: lower_ty(_lctx, &mt.ty), + mutbl: lower_mutability(_lctx, mt.mutbl), + } } -pub fn lower_opt_bounds(_lctx: &LoweringContext, b: &Option>) +pub fn lower_opt_bounds(_lctx: &LoweringContext, + b: &Option>) -> Option> { b.as_ref().map(|ref bounds| lower_bounds(_lctx, bounds)) } @@ -444,10 +566,6 @@ fn lower_bounds(_lctx: &LoweringContext, bounds: &TyParamBounds) -> hir::TyParam bounds.iter().map(|bound| lower_ty_param_bound(_lctx, bound)).collect() } -fn lower_variant_arg(_lctx: &LoweringContext, va: &VariantArg) -> hir::VariantArg { - hir::VariantArg { id: va.id, ty: lower_ty(_lctx, &va.ty) } -} - pub fn lower_block(_lctx: &LoweringContext, b: &Block) -> P { P(hir::Block { id: b.id, @@ -465,20 +583,20 @@ pub fn lower_item_underscore(_lctx: &LoweringContext, i: &Item_) -> hir::Item_ { hir::ItemUse(lower_view_path(_lctx, view_path)) } ItemStatic(ref t, m, ref e) => { - hir::ItemStatic(lower_ty(_lctx, t), lower_mutability(_lctx, m), lower_expr(_lctx, e)) + hir::ItemStatic(lower_ty(_lctx, t), + lower_mutability(_lctx, m), + lower_expr(_lctx, e)) } ItemConst(ref t, ref e) => { hir::ItemConst(lower_ty(_lctx, t), lower_expr(_lctx, e)) } ItemFn(ref decl, unsafety, constness, abi, ref generics, ref body) => { - hir::ItemFn( - lower_fn_decl(_lctx, decl), - lower_unsafety(_lctx, unsafety), - lower_constness(_lctx, constness), - abi, - lower_generics(_lctx, generics), - lower_block(_lctx, body) - ) + hir::ItemFn(lower_fn_decl(_lctx, decl), + lower_unsafety(_lctx, unsafety), + lower_constness(_lctx, constness), + abi, + lower_generics(_lctx, generics), + lower_block(_lctx, body)) } ItemMod(ref m) => hir::ItemMod(lower_mod(_lctx, m)), ItemForeignMod(ref nm) => hir::ItemForeignMod(lower_foreign_mod(_lctx, nm)), @@ -486,24 +604,26 @@ pub fn lower_item_underscore(_lctx: &LoweringContext, i: &Item_) -> hir::Item_ { hir::ItemTy(lower_ty(_lctx, t), lower_generics(_lctx, generics)) } ItemEnum(ref enum_definition, ref generics) => { - hir::ItemEnum( - hir::EnumDef { - variants: enum_definition.variants.iter().map(|x| { - lower_variant(_lctx, x) - }).collect(), - }, - lower_generics(_lctx, generics)) + hir::ItemEnum(hir::EnumDef { + variants: enum_definition.variants + .iter() + .map(|x| lower_variant(_lctx, x)) + .collect(), + }, + lower_generics(_lctx, generics)) } ItemStruct(ref struct_def, ref generics) => { let struct_def = lower_struct_def(_lctx, struct_def); hir::ItemStruct(struct_def, lower_generics(_lctx, generics)) } ItemDefaultImpl(unsafety, ref trait_ref) => { - hir::ItemDefaultImpl(lower_unsafety(_lctx, unsafety), lower_trait_ref(_lctx, trait_ref)) + hir::ItemDefaultImpl(lower_unsafety(_lctx, unsafety), + lower_trait_ref(_lctx, trait_ref)) } ItemImpl(unsafety, polarity, ref generics, ref ifce, ref ty, ref impl_items) => { - let new_impl_items = - impl_items.iter().map(|item| lower_impl_item(_lctx, item)).collect(); + let new_impl_items = impl_items.iter() + .map(|item| lower_impl_item(_lctx, item)) + .collect(); let ifce = ifce.as_ref().map(|trait_ref| lower_trait_ref(_lctx, trait_ref)); hir::ItemImpl(lower_unsafety(_lctx, unsafety), lower_impl_polarity(_lctx, polarity), @@ -549,11 +669,11 @@ pub fn lower_trait_item(_lctx: &LoweringContext, i: &TraitItem) -> P P { P(hir::ImplItem { - id: i.id, - name: i.ident.name, - attrs: i.attrs.clone(), - vis: lower_visibility(_lctx, i.vis), - node: match i.node { + id: i.id, + name: i.ident.name, + attrs: i.attrs.clone(), + vis: lower_visibility(_lctx, i.vis), + node: match i.node { ConstImplItem(ref ty, ref expr) => { hir::ConstImplItem(lower_ty(_lctx, ty), lower_expr(_lctx, expr)) } @@ -569,7 +689,10 @@ pub fn lower_impl_item(_lctx: &LoweringContext, i: &ImplItem) -> P hir::Mod { - hir::Mod { inner: m.inner, items: m.items.iter().map(|x| lower_item(_lctx, x)).collect() } + hir::Mod { + inner: m.inner, + items: m.items.iter().map(|x| lower_item(_lctx, x)).collect(), + } } pub fn lower_crate(_lctx: &LoweringContext, c: &Crate) -> hir::Crate { @@ -622,15 +745,16 @@ pub fn lower_foreign_item(_lctx: &LoweringContext, i: &ForeignItem) -> P { - hir::ForeignItemFn(lower_fn_decl(_lctx, fdec), lower_generics(_lctx, generics)) + hir::ForeignItemFn(lower_fn_decl(_lctx, fdec), + lower_generics(_lctx, generics)) } ForeignItemStatic(ref t, m) => { hir::ForeignItemStatic(lower_ty(_lctx, t), m) } }, - vis: lower_visibility(_lctx, i.vis), - span: i.span, - }) + vis: lower_visibility(_lctx, i.vis), + span: i.span, + }) } pub fn lower_method_sig(_lctx: &LoweringContext, sig: &MethodSig) -> hir::MethodSig { @@ -694,13 +818,13 @@ pub fn lower_binop(_lctx: &LoweringContext, b: BinOp) -> hir::BinOp { pub fn lower_pat(_lctx: &LoweringContext, p: &Pat) -> P { P(hir::Pat { - id: p.id, - node: match p.node { + id: p.id, + node: match p.node { PatWild(k) => hir::PatWild(lower_pat_wild_kind(_lctx, k)), PatIdent(ref binding_mode, pth1, ref sub) => { hir::PatIdent(lower_binding_mode(_lctx, binding_mode), - pth1, - sub.as_ref().map(|x| lower_pat(_lctx, x))) + pth1, + sub.as_ref().map(|x| lower_pat(_lctx, x))) } PatLit(ref e) => hir::PatLit(lower_expr(_lctx, e)), PatEnum(ref pth, ref pats) => { @@ -717,14 +841,18 @@ pub fn lower_pat(_lctx: &LoweringContext, p: &Pat) -> P { } PatStruct(ref pth, ref fields, etc) => { let pth = lower_path(_lctx, pth); - let fs = fields.iter().map(|f| { - Spanned { span: f.span, - node: hir::FieldPat { - name: f.node.ident.name, - pat: lower_pat(_lctx, &f.node.pat), - is_shorthand: f.node.is_shorthand, - }} - }).collect(); + let fs = fields.iter() + .map(|f| { + Spanned { + span: f.span, + node: hir::FieldPat { + name: f.node.ident.name, + pat: lower_pat(_lctx, &f.node.pat), + is_shorthand: f.node.is_shorthand, + }, + } + }) + .collect(); hir::PatStruct(pth, fs, etc) } PatTup(ref elts) => hir::PatTup(elts.iter().map(|x| lower_pat(_lctx, x)).collect()), @@ -733,11 +861,11 @@ pub fn lower_pat(_lctx: &LoweringContext, p: &Pat) -> P { lower_mutability(_lctx, mutbl)), PatRange(ref e1, ref e2) => { hir::PatRange(lower_expr(_lctx, e1), lower_expr(_lctx, e2)) - }, + } PatVec(ref before, ref slice, ref after) => { hir::PatVec(before.iter().map(|x| lower_pat(_lctx, x)).collect(), - slice.as_ref().map(|x| lower_pat(_lctx, x)), - after.iter().map(|x| lower_pat(_lctx, x)).collect()) + slice.as_ref().map(|x| lower_pat(_lctx, x)), + after.iter().map(|x| lower_pat(_lctx, x)).collect()) } PatMac(_) => panic!("Shouldn't exist here"), }, @@ -745,106 +873,293 @@ pub fn lower_pat(_lctx: &LoweringContext, p: &Pat) -> P { }) } +// RAII utility for setting and unsetting the cached id. +struct CachedIdSetter<'a> { + reset: bool, + lctx: &'a LoweringContext<'a>, +} + +impl<'a> CachedIdSetter<'a> { + fn new(lctx: &'a LoweringContext, expr_id: NodeId) -> CachedIdSetter<'a> { + // Only reset the id if it was previously 0, i.e., was not cached. + // If it was cached, we are in a nested node, but our id count will + // still count towards the parent's count. + let reset_cached_id = lctx.cached_id.get() == 0; + + let id_cache: &mut HashMap<_, _> = &mut lctx.id_cache.borrow_mut(); + + if id_cache.contains_key(&expr_id) { + let cached_id = lctx.cached_id.get(); + if cached_id == 0 { + // We're entering a node where we need to track ids, but are not + // yet tracking. + lctx.cached_id.set(id_cache[&expr_id]); + lctx.gensym_key.set(id_cache[&expr_id]); + } else { + // We're already tracking - check that the tracked id is the same + // as the expected id. + assert!(cached_id == id_cache[&expr_id], "id mismatch"); + } + } else { + let next_id = lctx.id_assigner.peek_node_id(); + id_cache.insert(expr_id, next_id); + lctx.gensym_key.set(next_id); + } + + CachedIdSetter { + reset: reset_cached_id, + lctx: lctx, + } + } +} + +impl<'a> Drop for CachedIdSetter<'a> { + fn drop(&mut self) { + if self.reset { + self.lctx.cached_id.set(0); + self.lctx.gensym_key.set(0); + } + } +} + pub fn lower_expr(lctx: &LoweringContext, e: &Expr) -> P { P(hir::Expr { - id: e.id, - node: match e.node { - ExprBox(ref e) => { - hir::ExprBox(lower_expr(lctx, e)) - } - ExprVec(ref exprs) => { - hir::ExprVec(exprs.iter().map(|x| lower_expr(lctx, x)).collect()) - } - ExprRepeat(ref expr, ref count) => { - hir::ExprRepeat(lower_expr(lctx, expr), lower_expr(lctx, count)) - } - ExprTup(ref elts) => { - hir::ExprTup(elts.iter().map(|x| lower_expr(lctx, x)).collect()) - } - ExprCall(ref f, ref args) => { - hir::ExprCall(lower_expr(lctx, f), - args.iter().map(|x| lower_expr(lctx, x)).collect()) - } - ExprMethodCall(i, ref tps, ref args) => { - hir::ExprMethodCall( - respan(i.span, i.node.name), - tps.iter().map(|x| lower_ty(lctx, x)).collect(), - args.iter().map(|x| lower_expr(lctx, x)).collect()) - } - ExprBinary(binop, ref lhs, ref rhs) => { - hir::ExprBinary(lower_binop(lctx, binop), - lower_expr(lctx, lhs), - lower_expr(lctx, rhs)) - } - ExprUnary(op, ref ohs) => { - hir::ExprUnary(lower_unop(lctx, op), lower_expr(lctx, ohs)) - } - ExprLit(ref l) => hir::ExprLit(P((**l).clone())), - ExprCast(ref expr, ref ty) => { - hir::ExprCast(lower_expr(lctx, expr), lower_ty(lctx, ty)) - } - ExprAddrOf(m, ref ohs) => { - hir::ExprAddrOf(lower_mutability(lctx, m), lower_expr(lctx, ohs)) - } - ExprIf(ref cond, ref tr, ref fl) => { - hir::ExprIf(lower_expr(lctx, cond), - lower_block(lctx, tr), - fl.as_ref().map(|x| lower_expr(lctx, x))) - } - ExprWhile(ref cond, ref body, opt_ident) => { - hir::ExprWhile(lower_expr(lctx, cond), - lower_block(lctx, body), - opt_ident) - } - ExprLoop(ref body, opt_ident) => { - hir::ExprLoop(lower_block(lctx, body), - opt_ident) - } - ExprMatch(ref expr, ref arms, ref source) => { - hir::ExprMatch(lower_expr(lctx, expr), - arms.iter().map(|x| lower_arm(lctx, x)).collect(), - lower_match_source(lctx, source)) - } - ExprClosure(capture_clause, ref decl, ref body) => { - hir::ExprClosure(lower_capture_clause(lctx, capture_clause), - lower_fn_decl(lctx, decl), - lower_block(lctx, body)) - } - ExprBlock(ref blk) => hir::ExprBlock(lower_block(lctx, blk)), - ExprAssign(ref el, ref er) => { - hir::ExprAssign(lower_expr(lctx, el), lower_expr(lctx, er)) - } - ExprAssignOp(op, ref el, ref er) => { - hir::ExprAssignOp(lower_binop(lctx, op), - lower_expr(lctx, el), - lower_expr(lctx, er)) - } - ExprField(ref el, ident) => { - hir::ExprField(lower_expr(lctx, el), respan(ident.span, ident.node.name)) - } - ExprTupField(ref el, ident) => { - hir::ExprTupField(lower_expr(lctx, el), ident) - } - ExprIndex(ref el, ref er) => { - hir::ExprIndex(lower_expr(lctx, el), lower_expr(lctx, er)) - } - ExprRange(ref e1, ref e2) => { - hir::ExprRange(e1.as_ref().map(|x| lower_expr(lctx, x)), - e2.as_ref().map(|x| lower_expr(lctx, x))) - } - ExprPath(ref qself, ref path) => { - let qself = qself.as_ref().map(|&QSelf { ref ty, position }| { - hir::QSelf { - ty: lower_ty(lctx, ty), - position: position + id: e.id, + node: match e.node { + // Issue #22181: + // Eventually a desugaring for `box EXPR` + // (similar to the desugaring above for `in PLACE BLOCK`) + // should go here, desugaring + // + // to: + // + // let mut place = BoxPlace::make_place(); + // let raw_place = Place::pointer(&mut place); + // let value = $value; + // unsafe { + // ::std::ptr::write(raw_place, value); + // Boxed::finalize(place) + // } + // + // But for now there are type-inference issues doing that. + ExprBox(ref e) => { + hir::ExprBox(lower_expr(lctx, e)) + } + + // Desugar ExprBox: `in (PLACE) EXPR` + ExprInPlace(ref placer, ref value_expr) => { + // to: + // + // let p = PLACE; + // let mut place = Placer::make_place(p); + // let raw_place = Place::pointer(&mut place); + // push_unsafe!({ + // std::intrinsics::move_val_init(raw_place, pop_unsafe!( EXPR )); + // InPlace::finalize(place) + // }) + let _old_cached = CachedIdSetter::new(lctx, e.id); + + let placer_expr = lower_expr(lctx, placer); + let value_expr = lower_expr(lctx, value_expr); + + let placer_ident = lctx.str_to_ident("placer"); + let agent_ident = lctx.str_to_ident("place"); + let p_ptr_ident = lctx.str_to_ident("p_ptr"); + + let make_place = ["ops", "Placer", "make_place"]; + let place_pointer = ["ops", "Place", "pointer"]; + let move_val_init = ["intrinsics", "move_val_init"]; + let inplace_finalize = ["ops", "InPlace", "finalize"]; + + let make_call = |lctx, p, args| { + let path = core_path(lctx, e.span, p); + let path = expr_path(lctx, path); + expr_call(lctx, e.span, path, args) + }; + + let mk_stmt_let = |lctx, bind, expr| stmt_let(lctx, e.span, false, bind, expr); + let mk_stmt_let_mut = |lctx, bind, expr| stmt_let(lctx, e.span, true, bind, expr); + + // let placer = ; + let s1 = mk_stmt_let(lctx, + placer_ident, + signal_block_expr(lctx, + vec![], + placer_expr, + e.span, + hir::PopUnstableBlock)); + + // let mut place = Placer::make_place(placer); + let s2 = { + let call = make_call(lctx, + &make_place, + vec![expr_ident(lctx, e.span, placer_ident)]); + mk_stmt_let_mut(lctx, agent_ident, call) + }; + + // let p_ptr = Place::pointer(&mut place); + let s3 = { + let args = vec![expr_mut_addr_of(lctx, + e.span, + expr_ident(lctx, e.span, agent_ident))]; + let call = make_call(lctx, &place_pointer, args); + mk_stmt_let(lctx, p_ptr_ident, call) + }; + + // pop_unsafe!(EXPR)); + let pop_unsafe_expr = + signal_block_expr(lctx, + vec![], + signal_block_expr(lctx, + vec![], + value_expr, + e.span, + hir::PopUnstableBlock), + e.span, + hir::PopUnsafeBlock(hir::CompilerGenerated)); + + // push_unsafe!({ + // std::intrinsics::move_val_init(raw_place, pop_unsafe!( EXPR )); + // InPlace::finalize(place) + // }) + let expr = { + let call_move_val_init = hir::StmtSemi(make_call(lctx, + &move_val_init, + vec![expr_ident(lctx, e.span, p_ptr_ident), + pop_unsafe_expr]), + lctx.next_id()); + let call_move_val_init = respan(e.span, call_move_val_init); + + let call = make_call(lctx, + &inplace_finalize, + vec![expr_ident(lctx, e.span, agent_ident)]); + signal_block_expr(lctx, + vec![P(call_move_val_init)], + call, + e.span, + hir::PushUnsafeBlock(hir::CompilerGenerated)) + }; + + return signal_block_expr(lctx, + vec![s1, s2, s3], + expr, + e.span, + hir::PushUnstableBlock); + } + + ExprVec(ref exprs) => { + hir::ExprVec(exprs.iter().map(|x| lower_expr(lctx, x)).collect()) + } + ExprRepeat(ref expr, ref count) => { + hir::ExprRepeat(lower_expr(lctx, expr), lower_expr(lctx, count)) + } + ExprTup(ref elts) => { + hir::ExprTup(elts.iter().map(|x| lower_expr(lctx, x)).collect()) + } + ExprCall(ref f, ref args) => { + hir::ExprCall(lower_expr(lctx, f), + args.iter().map(|x| lower_expr(lctx, x)).collect()) + } + ExprMethodCall(i, ref tps, ref args) => { + hir::ExprMethodCall(respan(i.span, i.node.name), + tps.iter().map(|x| lower_ty(lctx, x)).collect(), + args.iter().map(|x| lower_expr(lctx, x)).collect()) + } + ExprBinary(binop, ref lhs, ref rhs) => { + hir::ExprBinary(lower_binop(lctx, binop), + lower_expr(lctx, lhs), + lower_expr(lctx, rhs)) + } + ExprUnary(op, ref ohs) => { + hir::ExprUnary(lower_unop(lctx, op), lower_expr(lctx, ohs)) + } + ExprLit(ref l) => hir::ExprLit(P((**l).clone())), + ExprCast(ref expr, ref ty) => { + hir::ExprCast(lower_expr(lctx, expr), lower_ty(lctx, ty)) + } + ExprAddrOf(m, ref ohs) => { + hir::ExprAddrOf(lower_mutability(lctx, m), lower_expr(lctx, ohs)) + } + // More complicated than you might expect because the else branch + // might be `if let`. + ExprIf(ref cond, ref blk, ref else_opt) => { + let else_opt = else_opt.as_ref().map(|els| { + match els.node { + ExprIfLet(..) => { + let _old_cached = CachedIdSetter::new(lctx, e.id); + // wrap the if-let expr in a block + let span = els.span; + let blk = P(hir::Block { + stmts: vec![], + expr: Some(lower_expr(lctx, els)), + id: lctx.next_id(), + rules: hir::DefaultBlock, + span: span, + }); + expr_block(lctx, blk) } - }); - hir::ExprPath(qself, lower_path(lctx, path)) - } - ExprBreak(opt_ident) => hir::ExprBreak(opt_ident), - ExprAgain(opt_ident) => hir::ExprAgain(opt_ident), - ExprRet(ref e) => hir::ExprRet(e.as_ref().map(|x| lower_expr(lctx, x))), - ExprInlineAsm(InlineAsm { + _ => lower_expr(lctx, els), + } + }); + + hir::ExprIf(lower_expr(lctx, cond), + lower_block(lctx, blk), + else_opt) + } + ExprWhile(ref cond, ref body, opt_ident) => { + hir::ExprWhile(lower_expr(lctx, cond), + lower_block(lctx, body), + opt_ident) + } + ExprLoop(ref body, opt_ident) => { + hir::ExprLoop(lower_block(lctx, body), opt_ident) + } + ExprMatch(ref expr, ref arms) => { + hir::ExprMatch(lower_expr(lctx, expr), + arms.iter().map(|x| lower_arm(lctx, x)).collect(), + hir::MatchSource::Normal) + } + ExprClosure(capture_clause, ref decl, ref body) => { + hir::ExprClosure(lower_capture_clause(lctx, capture_clause), + lower_fn_decl(lctx, decl), + lower_block(lctx, body)) + } + ExprBlock(ref blk) => hir::ExprBlock(lower_block(lctx, blk)), + ExprAssign(ref el, ref er) => { + hir::ExprAssign(lower_expr(lctx, el), lower_expr(lctx, er)) + } + ExprAssignOp(op, ref el, ref er) => { + hir::ExprAssignOp(lower_binop(lctx, op), + lower_expr(lctx, el), + lower_expr(lctx, er)) + } + ExprField(ref el, ident) => { + hir::ExprField(lower_expr(lctx, el), + respan(ident.span, ident.node.name)) + } + ExprTupField(ref el, ident) => { + hir::ExprTupField(lower_expr(lctx, el), ident) + } + ExprIndex(ref el, ref er) => { + hir::ExprIndex(lower_expr(lctx, el), lower_expr(lctx, er)) + } + ExprRange(ref e1, ref e2) => { + hir::ExprRange(e1.as_ref().map(|x| lower_expr(lctx, x)), + e2.as_ref().map(|x| lower_expr(lctx, x))) + } + ExprPath(ref qself, ref path) => { + let qself = qself.as_ref().map(|&QSelf { ref ty, position }| { + hir::QSelf { + ty: lower_ty(lctx, ty), + position: position, + } + }); + hir::ExprPath(qself, lower_path(lctx, path)) + } + ExprBreak(opt_ident) => hir::ExprBreak(opt_ident), + ExprAgain(opt_ident) => hir::ExprAgain(opt_ident), + ExprRet(ref e) => hir::ExprRet(e.as_ref().map(|x| lower_expr(lctx, x))), + ExprInlineAsm(InlineAsm { ref inputs, ref outputs, ref asm, @@ -855,143 +1170,273 @@ pub fn lower_expr(lctx: &LoweringContext, e: &Expr) -> P { dialect, expn_id, }) => hir::ExprInlineAsm(hir::InlineAsm { - inputs: inputs.iter().map(|&(ref c, ref input)| { - (c.clone(), lower_expr(lctx, input)) - }).collect(), - outputs: outputs.iter().map(|&(ref c, ref out, ref is_rw)| { - (c.clone(), lower_expr(lctx, out), *is_rw) - }).collect(), - asm: asm.clone(), - asm_str_style: asm_str_style, - clobbers: clobbers.clone(), - volatile: volatile, - alignstack: alignstack, - dialect: dialect, - expn_id: expn_id, - }), - ExprStruct(ref path, ref fields, ref maybe_expr) => { - hir::ExprStruct(lower_path(lctx, path), - fields.iter().map(|x| lower_field(lctx, x)).collect(), - maybe_expr.as_ref().map(|x| lower_expr(lctx, x))) - }, - ExprParen(ref ex) => { - return lower_expr(lctx, ex); - } - ExprInPlace(..) => { - panic!("todo"); - } - ExprIfLet(..) => { - panic!("todo"); - } - ExprWhileLet(..) => { - panic!("todo"); - } + inputs: inputs.iter() + .map(|&(ref c, ref input)| (c.clone(), lower_expr(lctx, input))) + .collect(), + outputs: outputs.iter() + .map(|&(ref c, ref out, ref is_rw)| { + (c.clone(), lower_expr(lctx, out), *is_rw) + }) + .collect(), + asm: asm.clone(), + asm_str_style: asm_str_style, + clobbers: clobbers.clone(), + volatile: volatile, + alignstack: alignstack, + dialect: dialect, + expn_id: expn_id, + }), + ExprStruct(ref path, ref fields, ref maybe_expr) => { + hir::ExprStruct(lower_path(lctx, path), + fields.iter().map(|x| lower_field(lctx, x)).collect(), + maybe_expr.as_ref().map(|x| lower_expr(lctx, x))) + } + ExprParen(ref ex) => { + return lower_expr(lctx, ex); + } - // Desugar ExprForLoop - // From: `[opt_ident]: for in ` - ExprForLoop(ref pat, ref head, ref body, ref opt_ident) => { - // to: - // - // { - // let result = match ::std::iter::IntoIterator::into_iter() { - // mut iter => { - // [opt_ident]: loop { - // match ::std::iter::Iterator::next(&mut iter) { - // ::std::option::Option::Some() => , - // ::std::option::Option::None => break - // } - // } - // } - // }; - // result - // } - - // expand - let head = lower_expr(lctx, head); - - let iter = token::gensym_ident("iter"); - - // `::std::option::Option::Some() => ` - let pat_arm = { - let body_block = lower_block(lctx, body); - let body_span = body_block.span; - let body_expr = P(hir::Expr { - id: lctx.next_id(), - node: hir::ExprBlock(body_block), - span: body_span, + // Desugar ExprIfLet + // From: `if let = []` + ExprIfLet(ref pat, ref sub_expr, ref body, ref else_opt) => { + // to: + // + // match { + // => , + // [_ if => ,] + // _ => [ | ()] + // } + + let _old_cached = CachedIdSetter::new(lctx, e.id); + + // ` => ` + let pat_arm = { + let body_expr = expr_block(lctx, lower_block(lctx, body)); + arm(vec![lower_pat(lctx, pat)], body_expr) + }; + + // `[_ if => ,]` + let mut else_opt = else_opt.as_ref().map(|e| lower_expr(lctx, e)); + let else_if_arms = { + let mut arms = vec![]; + loop { + let else_opt_continue = else_opt.and_then(|els| { + els.and_then(|els| { + match els.node { + // else if + hir::ExprIf(cond, then, else_opt) => { + let pat_under = pat_wild(lctx, e.span); + arms.push(hir::Arm { + attrs: vec![], + pats: vec![pat_under], + guard: Some(cond), + body: expr_block(lctx, then), + }); + else_opt.map(|else_opt| (else_opt, true)) + } + _ => Some((P(els), false)), + } + }) }); - let pat = lower_pat(lctx, pat); - let some_pat = pat_some(lctx, e.span, pat); + match else_opt_continue { + Some((e, true)) => { + else_opt = Some(e); + } + Some((e, false)) => { + else_opt = Some(e); + break; + } + None => { + else_opt = None; + break; + } + } + } + arms + }; - arm(vec![some_pat], body_expr) - }; + let contains_else_clause = else_opt.is_some(); + + // `_ => [ | ()]` + let else_arm = { + let pat_under = pat_wild(lctx, e.span); + let else_expr = else_opt.unwrap_or_else(|| expr_tuple(lctx, e.span, vec![])); + arm(vec![pat_under], else_expr) + }; - // `::std::option::Option::None => break` - let break_arm = { - let break_expr = expr_break(lctx, e.span); + let mut arms = Vec::with_capacity(else_if_arms.len() + 2); + arms.push(pat_arm); + arms.extend(else_if_arms); + arms.push(else_arm); + + let match_expr = expr(lctx, + e.span, + hir::ExprMatch(lower_expr(lctx, sub_expr), + arms, + hir::MatchSource::IfLetDesugar { + contains_else_clause: contains_else_clause, + })); + return match_expr; + } - arm(vec![pat_none(lctx, e.span)], break_expr) - }; + // Desugar ExprWhileLet + // From: `[opt_ident]: while let = ` + ExprWhileLet(ref pat, ref sub_expr, ref body, opt_ident) => { + // to: + // + // [opt_ident]: loop { + // match { + // => , + // _ => break + // } + // } + + let _old_cached = CachedIdSetter::new(lctx, e.id); + + // ` => ` + let pat_arm = { + let body_expr = expr_block(lctx, lower_block(lctx, body)); + arm(vec![lower_pat(lctx, pat)], body_expr) + }; - // `match ::std::iter::Iterator::next(&mut iter) { ... }` - let match_expr = { - let next_path = { - let strs = std_path(lctx, &["iter", "Iterator", "next"]); - - path_global(e.span, strs) - }; - let ref_mut_iter = expr_mut_addr_of(lctx, e.span, expr_ident(lctx, e.span, iter)); - let next_expr = - expr_call(lctx, e.span, expr_path(lctx, next_path), vec![ref_mut_iter]); - let arms = vec![pat_arm, break_arm]; - - expr(lctx, - e.span, - hir::ExprMatch(next_expr, arms, hir::MatchSource::ForLoopDesugar)) - }; + // `_ => break` + let break_arm = { + let pat_under = pat_wild(lctx, e.span); + let break_expr = expr_break(lctx, e.span); + arm(vec![pat_under], break_expr) + }; - // `[opt_ident]: loop { ... }` - let loop_block = block_expr(lctx, match_expr); - let loop_expr = expr(lctx, e.span, hir::ExprLoop(loop_block, opt_ident.clone())); + // `match { ... }` + let arms = vec![pat_arm, break_arm]; + let match_expr = expr(lctx, + e.span, + hir::ExprMatch(lower_expr(lctx, sub_expr), + arms, + hir::MatchSource::WhileLetDesugar)); + + // `[opt_ident]: loop { ... }` + let loop_block = block_expr(lctx, match_expr); + return expr(lctx, e.span, hir::ExprLoop(loop_block, opt_ident)); + } - // `mut iter => { ... }` - let iter_arm = { - let iter_pat = - pat_ident_binding_mode(lctx, e.span, iter, hir::BindByValue(hir::MutMutable)); - arm(vec![iter_pat], loop_expr) + // Desugar ExprForLoop + // From: `[opt_ident]: for in ` + ExprForLoop(ref pat, ref head, ref body, opt_ident) => { + // to: + // + // { + // let result = match ::std::iter::IntoIterator::into_iter() { + // mut iter => { + // [opt_ident]: loop { + // match ::std::iter::Iterator::next(&mut iter) { + // ::std::option::Option::Some() => , + // ::std::option::Option::None => break + // } + // } + // } + // }; + // result + // } + + let _old_cached = CachedIdSetter::new(lctx, e.id); + + // expand + let head = lower_expr(lctx, head); + + let iter = lctx.str_to_ident("iter"); + + // `::std::option::Option::Some() => ` + let pat_arm = { + let body_block = lower_block(lctx, body); + let body_span = body_block.span; + let body_expr = P(hir::Expr { + id: lctx.next_id(), + node: hir::ExprBlock(body_block), + span: body_span, + }); + let pat = lower_pat(lctx, pat); + let some_pat = pat_some(lctx, e.span, pat); + + arm(vec![some_pat], body_expr) + }; + + // `::std::option::Option::None => break` + let break_arm = { + let break_expr = expr_break(lctx, e.span); + + arm(vec![pat_none(lctx, e.span)], break_expr) + }; + + // `match ::std::iter::Iterator::next(&mut iter) { ... }` + let match_expr = { + let next_path = { + let strs = std_path(lctx, &["iter", "Iterator", "next"]); + + path_global(e.span, strs) }; + let ref_mut_iter = expr_mut_addr_of(lctx, + e.span, + expr_ident(lctx, e.span, iter)); + let next_expr = expr_call(lctx, + e.span, + expr_path(lctx, next_path), + vec![ref_mut_iter]); + let arms = vec![pat_arm, break_arm]; + + expr(lctx, + e.span, + hir::ExprMatch(next_expr, arms, hir::MatchSource::ForLoopDesugar)) + }; - // `match ::std::iter::IntoIterator::into_iter() { ... }` - let into_iter_expr = { - let into_iter_path = { - let strs = std_path(lctx, &["iter", "IntoIterator", "into_iter"]); + // `[opt_ident]: loop { ... }` + let loop_block = block_expr(lctx, match_expr); + let loop_expr = expr(lctx, e.span, hir::ExprLoop(loop_block, opt_ident)); + + // `mut iter => { ... }` + let iter_arm = { + let iter_pat = pat_ident_binding_mode(lctx, + e.span, + iter, + hir::BindByValue(hir::MutMutable)); + arm(vec![iter_pat], loop_expr) + }; - path_global(e.span, strs) - }; + // `match ::std::iter::IntoIterator::into_iter() { ... }` + let into_iter_expr = { + let into_iter_path = { + let strs = std_path(lctx, &["iter", "IntoIterator", "into_iter"]); - expr_call(lctx, e.span, expr_path(lctx, into_iter_path), vec![head]) + path_global(e.span, strs) }; - let match_expr = expr_match(lctx, e.span, into_iter_expr, vec![iter_arm]); - - // `{ let result = ...; result }` - let result_ident = token::gensym_ident("result"); - let result = expr_block(lctx, - block_all(lctx, - e.span, - vec![stmt_let(lctx, - e.span, - false, - result_ident, - match_expr)], - Some(expr_ident(lctx, e.span, result_ident)))); - return result; - } + expr_call(lctx, + e.span, + expr_path(lctx, into_iter_path), + vec![head]) + }; - ExprMac(_) => panic!("Shouldn't exist here"), - }, - span: e.span, - }) + let match_expr = expr_match(lctx, + e.span, + into_iter_expr, + vec![iter_arm], + hir::MatchSource::ForLoopDesugar); + + // `{ let result = ...; result }` + let result_ident = lctx.str_to_ident("result"); + return expr_block(lctx, + block_all(lctx, + e.span, + vec![stmt_let(lctx, + e.span, + false, + result_ident, + match_expr)], + Some(expr_ident(lctx, e.span, result_ident)))) + } + + ExprMac(_) => panic!("Shouldn't exist here"), + }, + span: e.span, + }) } pub fn lower_stmt(_lctx: &LoweringContext, s: &Stmt) -> P { @@ -999,36 +1444,25 @@ pub fn lower_stmt(_lctx: &LoweringContext, s: &Stmt) -> P { StmtDecl(ref d, id) => { P(Spanned { node: hir::StmtDecl(lower_decl(_lctx, d), id), - span: s.span + span: s.span, }) } StmtExpr(ref e, id) => { P(Spanned { node: hir::StmtExpr(lower_expr(_lctx, e), id), - span: s.span + span: s.span, }) } StmtSemi(ref e, id) => { P(Spanned { node: hir::StmtSemi(lower_expr(_lctx, e), id), - span: s.span + span: s.span, }) } StmtMac(..) => panic!("Shouldn't exist here"), } } -pub fn lower_match_source(_lctx: &LoweringContext, m: &MatchSource) -> hir::MatchSource { - match *m { - MatchSource::Normal => hir::MatchSource::Normal, - MatchSource::IfLetDesugar { contains_else_clause } => { - hir::MatchSource::IfLetDesugar { contains_else_clause: contains_else_clause } - } - MatchSource::WhileLetDesugar => hir::MatchSource::WhileLetDesugar, - MatchSource::ForLoopDesugar => hir::MatchSource::ForLoopDesugar, - } -} - pub fn lower_capture_clause(_lctx: &LoweringContext, c: CaptureClause) -> hir::CaptureClause { match c { CaptureByValue => hir::CaptureByValue, @@ -1105,7 +1539,7 @@ fn arm(pats: Vec>, expr: P) -> hir::Arm { attrs: vec!(), pats: pats, guard: None, - body: expr + body: expr, } } @@ -1113,7 +1547,11 @@ fn expr_break(lctx: &LoweringContext, span: Span) -> P { expr(lctx, span, hir::ExprBreak(None)) } -fn expr_call(lctx: &LoweringContext, span: Span, e: P, args: Vec>) -> P { +fn expr_call(lctx: &LoweringContext, + span: Span, + e: P, + args: Vec>) + -> P { expr(lctx, span, hir::ExprCall(e, args)) } @@ -1129,14 +1567,25 @@ fn expr_path(lctx: &LoweringContext, path: hir::Path) -> P { expr(lctx, path.span, hir::ExprPath(None, path)) } -fn expr_match(lctx: &LoweringContext, span: Span, arg: P, arms: Vec) -> P { - expr(lctx, span, hir::ExprMatch(arg, arms, hir::MatchSource::Normal)) +fn expr_match(lctx: &LoweringContext, + span: Span, + arg: P, + arms: Vec, + source: hir::MatchSource) + -> P { + expr(lctx, + span, + hir::ExprMatch(arg, arms, source)) } fn expr_block(lctx: &LoweringContext, b: P) -> P { expr(lctx, b.span, hir::ExprBlock(b)) } +fn expr_tuple(lctx: &LoweringContext, sp: Span, exprs: Vec>) -> P { + expr(lctx, sp, hir::ExprTup(exprs)) +} + fn expr(lctx: &LoweringContext, span: Span, node: hir::Expr_) -> P { P(hir::Expr { id: lctx.next_id(), @@ -1145,7 +1594,12 @@ fn expr(lctx: &LoweringContext, span: Span, node: hir::Expr_) -> P { }) } -fn stmt_let(lctx: &LoweringContext, sp: Span, mutbl: bool, ident: Ident, ex: P) -> P { +fn stmt_let(lctx: &LoweringContext, + sp: Span, + mutbl: bool, + ident: Ident, + ex: P) + -> P { let pat = if mutbl { pat_ident_binding_mode(lctx, sp, ident, hir::BindByValue(hir::MutMutable)) } else { @@ -1169,14 +1623,15 @@ fn block_expr(lctx: &LoweringContext, expr: P) -> P { fn block_all(lctx: &LoweringContext, span: Span, stmts: Vec>, - expr: Option>) -> P { - P(hir::Block { - stmts: stmts, - expr: expr, - id: lctx.next_id(), - rules: hir::DefaultBlock, - span: span, - }) + expr: Option>) + -> P { + P(hir::Block { + stmts: stmts, + expr: expr, + id: lctx.next_id(), + rules: hir::DefaultBlock, + span: span, + }) } fn pat_some(lctx: &LoweringContext, span: Span, pat: P) -> P { @@ -1191,7 +1646,11 @@ fn pat_none(lctx: &LoweringContext, span: Span) -> P { pat_enum(lctx, span, path, vec![]) } -fn pat_enum(lctx: &LoweringContext, span: Span, path: hir::Path, subpats: Vec>) -> P { +fn pat_enum(lctx: &LoweringContext, + span: Span, + path: hir::Path, + subpats: Vec>) + -> P { let pt = hir::PatEnum(path, Some(subpats)); pat(lctx, span, pt) } @@ -1203,49 +1662,64 @@ fn pat_ident(lctx: &LoweringContext, span: Span, ident: Ident) -> P { fn pat_ident_binding_mode(lctx: &LoweringContext, span: Span, ident: Ident, - bm: hir::BindingMode) -> P { - let pat_ident = hir::PatIdent(bm, Spanned{span: span, node: ident}, None); + bm: hir::BindingMode) + -> P { + let pat_ident = hir::PatIdent(bm, + Spanned { + span: span, + node: ident, + }, + None); pat(lctx, span, pat_ident) } +fn pat_wild(lctx: &LoweringContext, span: Span) -> P { + pat(lctx, span, hir::PatWild(hir::PatWildSingle)) +} + fn pat(lctx: &LoweringContext, span: Span, pat: hir::Pat_) -> P { - P(hir::Pat { id: lctx.next_id(), node: pat, span: span }) + P(hir::Pat { + id: lctx.next_id(), + node: pat, + span: span, + }) } fn path_ident(span: Span, id: Ident) -> hir::Path { path(span, vec!(id)) } -fn path(span: Span, strs: Vec ) -> hir::Path { +fn path(span: Span, strs: Vec) -> hir::Path { path_all(span, false, strs, Vec::new(), Vec::new(), Vec::new()) } -fn path_global(span: Span, strs: Vec ) -> hir::Path { +fn path_global(span: Span, strs: Vec) -> hir::Path { path_all(span, true, strs, Vec::new(), Vec::new(), Vec::new()) } fn path_all(sp: Span, global: bool, - mut idents: Vec , + mut idents: Vec, lifetimes: Vec, types: Vec>, - bindings: Vec> ) + bindings: Vec>) -> hir::Path { let last_identifier = idents.pop().unwrap(); let mut segments: Vec = idents.into_iter() .map(|ident| { - hir::PathSegment { - identifier: ident, - parameters: hir::PathParameters::none(), - } - }).collect(); + hir::PathSegment { + identifier: ident, + parameters: hir::PathParameters::none(), + } + }) + .collect(); segments.push(hir::PathSegment { identifier: last_identifier, parameters: hir::AngleBracketedParameters(hir::AngleBracketedParameterData { lifetimes: lifetimes, types: OwnedSlice::from_vec(types), bindings: OwnedSlice::from_vec(bindings), - }) + }), }); hir::Path { span: sp, @@ -1262,3 +1736,126 @@ fn std_path(lctx: &LoweringContext, components: &[&str]) -> Vec { v.extend(components.iter().map(|s| str_to_ident(s))); return v } + +// Given suffix ["b","c","d"], returns path `::std::b::c::d` when +// `fld.cx.use_std`, and `::core::b::c::d` otherwise. +fn core_path(lctx: &LoweringContext, span: Span, components: &[&str]) -> hir::Path { + let idents = std_path(lctx, components); + path_global(span, idents) +} + +fn signal_block_expr(lctx: &LoweringContext, + stmts: Vec>, + expr: P, + span: Span, + rule: hir::BlockCheckMode) + -> P { + expr_block(lctx, + P(hir::Block { + rules: rule, + span: span, + id: lctx.next_id(), + stmts: stmts, + expr: Some(expr), + })) +} + + + +#[cfg(test)] +mod test { + use super::*; + use syntax::ast::{self, NodeId, NodeIdAssigner}; + use syntax::{parse, codemap}; + use syntax::fold::Folder; + use std::cell::Cell; + + struct MockAssigner { + next_id: Cell, + } + + impl MockAssigner { + fn new() -> MockAssigner { + MockAssigner { + next_id: Cell::new(0), + } + } + } + + trait FakeExtCtxt { + fn call_site(&self) -> codemap::Span; + fn cfg(&self) -> ast::CrateConfig; + fn ident_of(&self, st: &str) -> ast::Ident; + fn name_of(&self, st: &str) -> ast::Name; + fn parse_sess(&self) -> &parse::ParseSess; + } + + impl FakeExtCtxt for parse::ParseSess { + fn call_site(&self) -> codemap::Span { + codemap::Span { + lo: codemap::BytePos(0), + hi: codemap::BytePos(0), + expn_id: codemap::NO_EXPANSION, + } + } + fn cfg(&self) -> ast::CrateConfig { Vec::new() } + fn ident_of(&self, st: &str) -> ast::Ident { + parse::token::str_to_ident(st) + } + fn name_of(&self, st: &str) -> ast::Name { + parse::token::intern(st) + } + fn parse_sess(&self) -> &parse::ParseSess { self } + } + + impl NodeIdAssigner for MockAssigner { + fn next_node_id(&self) -> NodeId { + let result = self.next_id.get(); + self.next_id.set(result + 1); + result + } + + fn peek_node_id(&self) -> NodeId { + self.next_id.get() + } + } + + impl Folder for MockAssigner { + fn new_id(&mut self, old_id: NodeId) -> NodeId { + assert_eq!(old_id, ast::DUMMY_NODE_ID); + self.next_node_id() + } + } + + #[test] + fn test_preserves_ids() { + let cx = parse::ParseSess::new(); + let mut assigner = MockAssigner::new(); + + let ast_if_let = quote_expr!(&cx, if let Some(foo) = baz { bar(foo); }); + let ast_if_let = assigner.fold_expr(ast_if_let); + let ast_while_let = quote_expr!(&cx, while let Some(foo) = baz { bar(foo); }); + let ast_while_let = assigner.fold_expr(ast_while_let); + let ast_for = quote_expr!(&cx, for i in 0..10 { foo(i); }); + let ast_for = assigner.fold_expr(ast_for); + let ast_in = quote_expr!(&cx, in HEAP { foo() }); + let ast_in = assigner.fold_expr(ast_in); + + let lctx = LoweringContext::new(&assigner, None); + let hir1 = lower_expr(&lctx, &ast_if_let); + let hir2 = lower_expr(&lctx, &ast_if_let); + assert!(hir1 == hir2); + + let hir1 = lower_expr(&lctx, &ast_while_let); + let hir2 = lower_expr(&lctx, &ast_while_let); + assert!(hir1 == hir2); + + let hir1 = lower_expr(&lctx, &ast_for); + let hir2 = lower_expr(&lctx, &ast_for); + assert!(hir1 == hir2); + + let hir1 = lower_expr(&lctx, &ast_in); + let hir2 = lower_expr(&lctx, &ast_in); + assert!(hir1 == hir2); + } +}