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};
32 #[derive(Copy, Clone, Debug)]
39 pub fn is_explicit(self) -> bool {
41 LintLevel::Inherited => false,
42 LintLevel::Explicit(_) => true
47 #[derive(Clone, Debug)]
48 pub struct Block<'tcx> {
49 pub targeted_by_break: bool,
50 pub region_scope: region::Scope,
51 pub opt_destruction_scope: Option<region::Scope>,
53 pub stmts: Vec<StmtRef<'tcx>>,
54 pub expr: Option<ExprRef<'tcx>>,
55 pub safety_mode: BlockSafety,
58 #[derive(Copy, Clone, Debug)]
59 pub enum BlockSafety {
61 ExplicitUnsafe(ast::NodeId),
66 #[derive(Clone, Debug)]
67 pub enum StmtRef<'tcx> {
68 Mirror(Box<Stmt<'tcx>>),
71 #[derive(Clone, Debug)]
72 pub struct Stmt<'tcx> {
73 pub kind: StmtKind<'tcx>,
74 pub opt_destruction_scope: Option<region::Scope>,
77 #[derive(Clone, Debug)]
78 pub enum StmtKind<'tcx> {
80 /// scope for this statement; may be used as lifetime of temporaries
83 /// expression being evaluated in this statement
88 /// scope for variables bound in this let; covers this and
89 /// remaining statements in block
90 remainder_scope: region::Scope,
92 /// scope for the initialization itself; might be used as
93 /// lifetime of temporaries
94 init_scope: region::Scope,
98 /// if a type is included, it is added as an ascription pattern
99 pattern: Pattern<'tcx>,
101 /// let pat: ty = <INIT> ...
102 initializer: Option<ExprRef<'tcx>>,
104 /// the lint level for this let-statement
105 lint_level: LintLevel,
109 /// The Hair trait implementor lowers their expressions (`&'tcx H::Expr`)
110 /// into instances of this `Expr` enum. This lowering can be done
111 /// basically as lazily or as eagerly as desired: every recursive
112 /// reference to an expression in this enum is an `ExprRef<'tcx>`, which
113 /// may in turn be another instance of this enum (boxed), or else an
114 /// unlowered `&'tcx H::Expr`. Note that instances of `Expr` are very
115 /// shortlived. They are created by `Hair::to_expr`, analyzed and
116 /// converted into MIR, and then discarded.
118 /// If you compare `Expr` to the full compiler AST, you will see it is
119 /// a good bit simpler. In fact, a number of the more straight-forward
120 /// MIR simplifications are already done in the impl of `Hair`. For
121 /// example, method calls and overloaded operators are absent: they are
122 /// expected to be converted into `Expr::Call` instances.
123 #[derive(Clone, Debug)]
124 pub struct Expr<'tcx> {
125 /// type of this expression
128 /// lifetime of this expression if it should be spilled into a
129 /// temporary; should be None only if in a constant context
130 pub temp_lifetime: Option<region::Scope>,
132 /// span of the expression in the source
135 /// kind of expression
136 pub kind: ExprKind<'tcx>,
139 #[derive(Clone, Debug)]
140 pub enum ExprKind<'tcx> {
142 region_scope: region::Scope,
143 lint_level: LintLevel,
144 value: ExprRef<'tcx>,
147 value: ExprRef<'tcx>,
152 args: Vec<ExprRef<'tcx>>,
153 // Whether this is from a call in HIR, rather than from an overloaded
154 // operator. True for overloaded function call.
159 }, // NOT overloaded!
164 }, // NOT overloaded!
169 }, // NOT overloaded!
170 // LogicalOp is distinct from BinaryOp because of lazy evaluation of the operands.
174 }, // NOT overloaded!
176 source: ExprRef<'tcx>,
179 source: ExprRef<'tcx>,
180 }, // Use a lexpr to get a vexpr.
182 source: ExprRef<'tcx>,
185 source: ExprRef<'tcx>,
188 source: ExprRef<'tcx>,
191 source: ExprRef<'tcx>,
194 source: ExprRef<'tcx>,
197 condition: ExprRef<'tcx>,
199 otherwise: Option<ExprRef<'tcx>>,
202 condition: Option<ExprRef<'tcx>>,
206 discriminant: ExprRef<'tcx>,
207 arms: Vec<Arm<'tcx>>,
210 body: &'tcx hir::Block,
227 index: ExprRef<'tcx>,
232 /// first argument, used for self in a closure
238 region: Region<'tcx>,
239 borrow_kind: BorrowKind,
243 label: region::Scope,
244 value: Option<ExprRef<'tcx>>,
247 label: region::Scope,
250 value: Option<ExprRef<'tcx>>,
253 value: ExprRef<'tcx>,
257 fields: Vec<ExprRef<'tcx>>,
260 fields: Vec<ExprRef<'tcx>>,
263 adt_def: &'tcx AdtDef,
264 variant_index: usize,
265 substs: &'tcx Substs<'tcx>,
267 /// Optional user-given substs: for something like `let x =
268 /// Bar::<T> { ... }`.
269 user_ty: Option<CanonicalTy<'tcx>>,
271 fields: Vec<FieldExprRef<'tcx>>,
272 base: Option<FruInfo<'tcx>>
274 PlaceTypeAscription {
275 source: ExprRef<'tcx>,
276 /// Type that the user gave to this expression
277 user_ty: CanonicalTy<'tcx>,
279 ValueTypeAscription {
280 source: ExprRef<'tcx>,
281 /// Type that the user gave to this expression
282 user_ty: CanonicalTy<'tcx>,
286 substs: UpvarSubsts<'tcx>,
287 upvars: Vec<ExprRef<'tcx>>,
288 movability: Option<hir::GeneratorMovability>,
291 literal: &'tcx Const<'tcx>,
293 /// Optional user-given type: for something like
294 /// `collect::<Vec<_>>`, this would be present and would
295 /// indicate that `Vec<_>` was explicitly specified.
297 /// Needed for NLL to impose user-given type constraints.
298 user_ty: Option<CanonicalTy<'tcx>>,
301 asm: &'tcx hir::InlineAsm,
302 outputs: Vec<ExprRef<'tcx>>,
303 inputs: Vec<ExprRef<'tcx>>
306 value: ExprRef<'tcx>,
310 #[derive(Clone, Debug)]
311 pub enum ExprRef<'tcx> {
312 Hair(&'tcx hir::Expr),
313 Mirror(Box<Expr<'tcx>>),
316 #[derive(Clone, Debug)]
317 pub struct FieldExprRef<'tcx> {
319 pub expr: ExprRef<'tcx>,
322 #[derive(Clone, Debug)]
323 pub struct FruInfo<'tcx> {
324 pub base: ExprRef<'tcx>,
325 pub field_types: Vec<Ty<'tcx>>
328 #[derive(Clone, Debug)]
329 pub struct Arm<'tcx> {
330 pub patterns: Vec<Pattern<'tcx>>,
331 pub guard: Option<Guard<'tcx>>,
332 pub body: ExprRef<'tcx>,
333 pub lint_level: LintLevel,
336 #[derive(Clone, Debug)]
337 pub enum Guard<'tcx> {
341 #[derive(Copy, Clone, Debug)]
347 impl<'tcx> ExprRef<'tcx> {
348 pub fn span(&self) -> Span {
350 ExprRef::Hair(expr) => expr.span,
351 ExprRef::Mirror(expr) => expr.span,
356 ///////////////////////////////////////////////////////////////////////////
359 /// "Mirroring" is the process of converting from a HIR type into one
360 /// of the HAIR types defined in this file. This is basically a "on
361 /// the fly" desugaring step that hides a lot of the messiness in the
362 /// tcx. For example, the mirror of a `&'tcx hir::Expr` is an
365 /// Mirroring is gradual: when you mirror an outer expression like `e1
366 /// + e2`, the references to the inner expressions `e1` and `e2` are
367 /// `ExprRef<'tcx>` instances, and they may or may not be eagerly
368 /// mirrored. This allows a single AST node from the compiler to
369 /// expand into one or more Hair nodes, which lets the Hair nodes be
371 pub trait Mirror<'tcx> {
374 fn make_mirror<'a, 'gcx>(self, cx: &mut Cx<'a, 'gcx, 'tcx>) -> Self::Output;
377 impl<'tcx> Mirror<'tcx> for Expr<'tcx> {
378 type Output = Expr<'tcx>;
380 fn make_mirror<'a, 'gcx>(self, _: &mut Cx<'a, 'gcx, 'tcx>) -> Expr<'tcx> {
385 impl<'tcx> Mirror<'tcx> for ExprRef<'tcx> {
386 type Output = Expr<'tcx>;
388 fn make_mirror<'a, 'gcx>(self, hir: &mut Cx<'a, 'gcx, 'tcx>) -> Expr<'tcx> {
390 ExprRef::Hair(h) => h.make_mirror(hir),
391 ExprRef::Mirror(m) => *m,
396 impl<'tcx> Mirror<'tcx> for Stmt<'tcx> {
397 type Output = Stmt<'tcx>;
399 fn make_mirror<'a, 'gcx>(self, _: &mut Cx<'a, 'gcx, 'tcx>) -> Stmt<'tcx> {
404 impl<'tcx> Mirror<'tcx> for StmtRef<'tcx> {
405 type Output = Stmt<'tcx>;
407 fn make_mirror<'a, 'gcx>(self, _: &mut Cx<'a, 'gcx, 'tcx>) -> Stmt<'tcx> {
409 StmtRef::Mirror(m) => *m,
414 impl<'tcx> Mirror<'tcx> for Block<'tcx> {
415 type Output = Block<'tcx>;
417 fn make_mirror<'a, 'gcx>(self, _: &mut Cx<'a, 'gcx, 'tcx>) -> Block<'tcx> {