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 //! The MIR is built from some high-level abstract IR
12 //! (HAIR). This section defines the HAIR along with a trait for
13 //! accessing it. The intention is to allow MIR construction to be
14 //! unit-tested and separated from the Rust source and compiler data
17 use rustc::mir::{BinOp, BorrowKind, Field, UnOp};
18 use rustc::hir::def_id::DefId;
19 use rustc::middle::region;
20 use rustc::ty::subst::Substs;
21 use rustc::ty::{AdtDef, CanonicalTy, UpvarSubsts, Region, Ty, Const};
30 pub use self::pattern::{BindingMode, Pattern, PatternKind, FieldPattern};
34 #[derive(Copy, Clone, Debug)]
41 pub fn is_explicit(self) -> bool {
43 LintLevel::Inherited => false,
44 LintLevel::Explicit(_) => true
49 #[derive(Clone, Debug)]
50 pub struct Block<'tcx> {
51 pub targeted_by_break: bool,
52 pub region_scope: region::Scope,
53 pub opt_destruction_scope: Option<region::Scope>,
55 pub stmts: Vec<StmtRef<'tcx>>,
56 pub expr: Option<ExprRef<'tcx>>,
57 pub safety_mode: BlockSafety,
60 #[derive(Copy, Clone, Debug)]
61 pub enum BlockSafety {
63 ExplicitUnsafe(ast::NodeId),
68 #[derive(Clone, Debug)]
69 pub enum StmtRef<'tcx> {
70 Mirror(Box<Stmt<'tcx>>),
73 #[derive(Clone, Debug)]
74 pub struct Stmt<'tcx> {
75 pub kind: StmtKind<'tcx>,
76 pub opt_destruction_scope: Option<region::Scope>,
79 #[derive(Clone, Debug)]
80 pub enum StmtKind<'tcx> {
82 /// scope for this statement; may be used as lifetime of temporaries
85 /// expression being evaluated in this statement
90 /// scope for variables bound in this let; covers this and
91 /// remaining statements in block
92 remainder_scope: region::Scope,
94 /// scope for the initialization itself; might be used as
95 /// lifetime of temporaries
96 init_scope: region::Scope,
100 /// if a type is included, it is added as an ascription pattern
101 pattern: Pattern<'tcx>,
103 /// let pat: ty = <INIT> ...
104 initializer: Option<ExprRef<'tcx>>,
106 /// the lint level for this let-statement
107 lint_level: LintLevel,
111 /// The Hair trait implementor lowers their expressions (`&'tcx H::Expr`)
112 /// into instances of this `Expr` enum. This lowering can be done
113 /// basically as lazily or as eagerly as desired: every recursive
114 /// reference to an expression in this enum is an `ExprRef<'tcx>`, which
115 /// may in turn be another instance of this enum (boxed), or else an
116 /// unlowered `&'tcx H::Expr`. Note that instances of `Expr` are very
117 /// shortlived. They are created by `Hair::to_expr`, analyzed and
118 /// converted into MIR, and then discarded.
120 /// If you compare `Expr` to the full compiler AST, you will see it is
121 /// a good bit simpler. In fact, a number of the more straight-forward
122 /// MIR simplifications are already done in the impl of `Hair`. For
123 /// example, method calls and overloaded operators are absent: they are
124 /// expected to be converted into `Expr::Call` instances.
125 #[derive(Clone, Debug)]
126 pub struct Expr<'tcx> {
127 /// type of this expression
130 /// lifetime of this expression if it should be spilled into a
131 /// temporary; should be None only if in a constant context
132 pub temp_lifetime: Option<region::Scope>,
134 /// span of the expression in the source
137 /// kind of expression
138 pub kind: ExprKind<'tcx>,
141 #[derive(Clone, Debug)]
142 pub enum ExprKind<'tcx> {
144 region_scope: region::Scope,
145 lint_level: LintLevel,
146 value: ExprRef<'tcx>,
149 value: ExprRef<'tcx>,
154 args: Vec<ExprRef<'tcx>>,
155 // Whether this is from a call in HIR, rather than from an overloaded
156 // operator. True for overloaded function call.
161 }, // NOT overloaded!
166 }, // NOT overloaded!
171 }, // NOT overloaded!
172 // LogicalOp is distinct from BinaryOp because of lazy evaluation of the operands.
176 }, // NOT overloaded!
178 source: ExprRef<'tcx>,
181 source: ExprRef<'tcx>,
182 }, // Use a lexpr to get a vexpr.
184 source: ExprRef<'tcx>,
187 source: ExprRef<'tcx>,
190 source: ExprRef<'tcx>,
193 source: ExprRef<'tcx>,
196 source: ExprRef<'tcx>,
199 condition: ExprRef<'tcx>,
201 otherwise: Option<ExprRef<'tcx>>,
204 condition: Option<ExprRef<'tcx>>,
208 discriminant: ExprRef<'tcx>,
209 arms: Vec<Arm<'tcx>>,
212 body: &'tcx hir::Block,
229 index: ExprRef<'tcx>,
234 /// first argument, used for self in a closure
240 region: Region<'tcx>,
241 borrow_kind: BorrowKind,
245 label: region::Scope,
246 value: Option<ExprRef<'tcx>>,
249 label: region::Scope,
252 value: Option<ExprRef<'tcx>>,
255 value: ExprRef<'tcx>,
259 fields: Vec<ExprRef<'tcx>>,
262 fields: Vec<ExprRef<'tcx>>,
265 adt_def: &'tcx AdtDef,
266 variant_index: usize,
267 substs: &'tcx Substs<'tcx>,
269 /// Optional user-given substs: for something like `let x =
270 /// Bar::<T> { ... }`.
271 user_ty: Option<CanonicalTy<'tcx>>,
273 fields: Vec<FieldExprRef<'tcx>>,
274 base: Option<FruInfo<'tcx>>
276 PlaceTypeAscription {
277 source: ExprRef<'tcx>,
278 /// Type that the user gave to this expression
279 user_ty: CanonicalTy<'tcx>,
281 ValueTypeAscription {
282 source: ExprRef<'tcx>,
283 /// Type that the user gave to this expression
284 user_ty: CanonicalTy<'tcx>,
288 substs: UpvarSubsts<'tcx>,
289 upvars: Vec<ExprRef<'tcx>>,
290 movability: Option<hir::GeneratorMovability>,
293 literal: &'tcx Const<'tcx>,
295 /// Optional user-given type: for something like
296 /// `collect::<Vec<_>>`, this would be present and would
297 /// indicate that `Vec<_>` was explicitly specified.
299 /// Needed for NLL to impose user-given type constraints.
300 user_ty: Option<CanonicalTy<'tcx>>,
303 asm: &'tcx hir::InlineAsm,
304 outputs: Vec<ExprRef<'tcx>>,
305 inputs: Vec<ExprRef<'tcx>>
308 value: ExprRef<'tcx>,
312 #[derive(Clone, Debug)]
313 pub enum ExprRef<'tcx> {
314 Hair(&'tcx hir::Expr),
315 Mirror(Box<Expr<'tcx>>),
318 #[derive(Clone, Debug)]
319 pub struct FieldExprRef<'tcx> {
321 pub expr: ExprRef<'tcx>,
324 #[derive(Clone, Debug)]
325 pub struct FruInfo<'tcx> {
326 pub base: ExprRef<'tcx>,
327 pub field_types: Vec<Ty<'tcx>>
330 #[derive(Clone, Debug)]
331 pub struct Arm<'tcx> {
332 pub patterns: Vec<Pattern<'tcx>>,
333 pub guard: Option<Guard<'tcx>>,
334 pub body: ExprRef<'tcx>,
335 pub lint_level: LintLevel,
338 #[derive(Clone, Debug)]
339 pub enum Guard<'tcx> {
343 #[derive(Copy, Clone, Debug)]
349 impl<'tcx> ExprRef<'tcx> {
350 pub fn span(&self) -> Span {
352 ExprRef::Hair(expr) => expr.span,
353 ExprRef::Mirror(expr) => expr.span,
358 ///////////////////////////////////////////////////////////////////////////
361 /// "Mirroring" is the process of converting from a HIR type into one
362 /// of the HAIR types defined in this file. This is basically a "on
363 /// the fly" desugaring step that hides a lot of the messiness in the
364 /// tcx. For example, the mirror of a `&'tcx hir::Expr` is an
367 /// Mirroring is gradual: when you mirror an outer expression like `e1
368 /// + e2`, the references to the inner expressions `e1` and `e2` are
369 /// `ExprRef<'tcx>` instances, and they may or may not be eagerly
370 /// mirrored. This allows a single AST node from the compiler to
371 /// expand into one or more Hair nodes, which lets the Hair nodes be
373 pub trait Mirror<'tcx> {
376 fn make_mirror<'a, 'gcx>(self, cx: &mut Cx<'a, 'gcx, 'tcx>) -> Self::Output;
379 impl<'tcx> Mirror<'tcx> for Expr<'tcx> {
380 type Output = Expr<'tcx>;
382 fn make_mirror<'a, 'gcx>(self, _: &mut Cx<'a, 'gcx, 'tcx>) -> Expr<'tcx> {
387 impl<'tcx> Mirror<'tcx> for ExprRef<'tcx> {
388 type Output = Expr<'tcx>;
390 fn make_mirror<'a, 'gcx>(self, hir: &mut Cx<'a, 'gcx, 'tcx>) -> Expr<'tcx> {
392 ExprRef::Hair(h) => h.make_mirror(hir),
393 ExprRef::Mirror(m) => *m,
398 impl<'tcx> Mirror<'tcx> for Stmt<'tcx> {
399 type Output = Stmt<'tcx>;
401 fn make_mirror<'a, 'gcx>(self, _: &mut Cx<'a, 'gcx, 'tcx>) -> Stmt<'tcx> {
406 impl<'tcx> Mirror<'tcx> for StmtRef<'tcx> {
407 type Output = Stmt<'tcx>;
409 fn make_mirror<'a, 'gcx>(self, _: &mut Cx<'a, 'gcx, 'tcx>) -> Stmt<'tcx> {
411 StmtRef::Mirror(m) => *m,
416 impl<'tcx> Mirror<'tcx> for Block<'tcx> {
417 type Output = Block<'tcx>;
419 fn make_mirror<'a, 'gcx>(self, _: &mut Cx<'a, 'gcx, 'tcx>) -> Block<'tcx> {