1 // Copyright 2012 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 // Type substitutions.
15 use middle::ty_fold::{TypeFoldable, TypeFolder};
16 use util::ppaux::Repr;
21 use std::slice::{Items, MutItems};
23 use syntax::codemap::{Span, DUMMY_SP};
25 ///////////////////////////////////////////////////////////////////////////
26 // HomogeneousTuple3 trait
28 // This could be moved into standard library at some point.
30 trait HomogeneousTuple3<T> {
31 fn len(&self) -> uint;
32 fn as_slice<'a>(&'a self) -> &'a [T];
33 fn as_mut_slice<'a>(&'a mut self) -> &'a mut [T];
34 fn iter<'a>(&'a self) -> Items<'a, T>;
35 fn mut_iter<'a>(&'a mut self) -> MutItems<'a, T>;
36 fn get<'a>(&'a self, index: uint) -> Option<&'a T>;
37 fn get_mut<'a>(&'a mut self, index: uint) -> Option<&'a mut T>;
40 impl<T> HomogeneousTuple3<T> for (T, T, T) {
41 fn len(&self) -> uint {
45 fn as_slice<'a>(&'a self) -> &'a [T] {
47 let ptr: *T = mem::transmute(self);
48 let slice = raw::Slice { data: ptr, len: 3 };
53 fn as_mut_slice<'a>(&'a mut self) -> &'a mut [T] {
55 let ptr: *T = mem::transmute(self);
56 let slice = raw::Slice { data: ptr, len: 3 };
61 fn iter<'a>(&'a self) -> Items<'a, T> {
62 let slice: &'a [T] = self.as_slice();
66 fn mut_iter<'a>(&'a mut self) -> MutItems<'a, T> {
67 self.as_mut_slice().mut_iter()
70 fn get<'a>(&'a self, index: uint) -> Option<&'a T> {
71 self.as_slice().get(index)
74 fn get_mut<'a>(&'a mut self, index: uint) -> Option<&'a mut T> {
75 Some(&mut self.as_mut_slice()[index]) // wrong: fallible
79 ///////////////////////////////////////////////////////////////////////////
82 * A substitution mapping type/region parameters to new values. We
83 * identify each in-scope parameter by an *index* and a *parameter
84 * space* (which indices where the parameter is defined; see
87 #[deriving(Clone, PartialEq, Eq, Hash)]
89 pub types: VecPerParamSpace<ty::t>,
90 pub regions: RegionSubsts,
94 * Represents the values to use when substituting lifetime parameters.
95 * If the value is `ErasedRegions`, then this subst is occurring during
96 * trans, and all region parameters will be replaced with `ty::ReStatic`. */
97 #[deriving(Clone, PartialEq, Eq, Hash)]
98 pub enum RegionSubsts {
100 NonerasedRegions(VecPerParamSpace<ty::Region>)
104 pub fn new(t: VecPerParamSpace<ty::t>,
105 r: VecPerParamSpace<ty::Region>)
108 Substs { types: t, regions: NonerasedRegions(r) }
111 pub fn new_type(t: Vec<ty::t>,
115 Substs::new(VecPerParamSpace::new(t, Vec::new(), Vec::new()),
116 VecPerParamSpace::new(r, Vec::new(), Vec::new()))
119 pub fn new_trait(t: Vec<ty::t>,
124 Substs::new(VecPerParamSpace::new(t, vec!(s), Vec::new()),
125 VecPerParamSpace::new(r, Vec::new(), Vec::new()))
128 pub fn erased(t: VecPerParamSpace<ty::t>) -> Substs
130 Substs { types: t, regions: ErasedRegions }
133 pub fn empty() -> Substs {
135 types: VecPerParamSpace::empty(),
136 regions: NonerasedRegions(VecPerParamSpace::empty()),
140 pub fn trans_empty() -> Substs {
142 types: VecPerParamSpace::empty(),
143 regions: ErasedRegions
147 pub fn is_noop(&self) -> bool {
148 let regions_is_noop = match self.regions {
149 ErasedRegions => false, // may be used to canonicalize
150 NonerasedRegions(ref regions) => regions.is_empty(),
153 regions_is_noop && self.types.is_empty()
156 pub fn self_ty(&self) -> Option<ty::t> {
157 self.types.get_self().map(|&t| t)
160 pub fn with_self_ty(&self, self_ty: ty::t) -> Substs {
161 assert!(self.self_ty().is_none());
162 let mut s = (*self).clone();
163 s.types.push(SelfSpace, self_ty);
167 pub fn regions<'a>(&'a self) -> &'a VecPerParamSpace<ty::Region> {
169 * Since ErasedRegions are only to be used in trans, most of
170 * the compiler can use this method to easily access the set
171 * of region substitutions.
175 ErasedRegions => fail!("Erased regions only expected in trans"),
176 NonerasedRegions(ref r) => r
180 pub fn mut_regions<'a>(&'a mut self) -> &'a mut VecPerParamSpace<ty::Region> {
182 * Since ErasedRegions are only to be used in trans, most of
183 * the compiler can use this method to easily access the set
184 * of region substitutions.
188 ErasedRegions => fail!("Erased regions only expected in trans"),
189 NonerasedRegions(ref mut r) => r
193 pub fn with_method_from(self, substs: &Substs) -> Substs {
194 self.with_method((*substs.types.get_vec(FnSpace)).clone(),
195 (*substs.regions().get_vec(FnSpace)).clone())
198 pub fn with_method(self,
200 m_regions: Vec<ty::Region>)
203 let Substs { types, regions } = self;
204 let types = types.with_vec(FnSpace, m_types);
205 let regions = regions.map(m_regions,
206 |r, m_regions| r.with_vec(FnSpace, m_regions));
207 Substs { types: types, regions: regions }
214 op: |VecPerParamSpace<ty::Region>, A| -> VecPerParamSpace<ty::Region>)
217 ErasedRegions => ErasedRegions,
218 NonerasedRegions(r) => NonerasedRegions(op(r, a))
223 ///////////////////////////////////////////////////////////////////////////
226 #[deriving(PartialOrd, Ord, PartialEq, Eq,
227 Clone, Hash, Encodable, Decodable, Show)]
228 pub enum ParamSpace {
229 TypeSpace, // Type parameters attached to a type definition, trait, or impl
230 SelfSpace, // Self parameter on a trait
231 FnSpace, // Type parameters attached to a method or fn
235 pub fn all() -> [ParamSpace, ..3] {
236 [TypeSpace, SelfSpace, FnSpace]
239 pub fn to_uint(self) -> uint {
247 pub fn from_uint(u: uint) -> ParamSpace {
252 _ => fail!("Invalid ParamSpace: {}", u)
258 * Vector of things sorted by param space. Used to keep
259 * the set of things declared on the type, self, or method
262 #[deriving(PartialEq, Eq, Clone, Hash, Encodable, Decodable)]
263 pub struct VecPerParamSpace<T> {
264 vecs: (Vec<T>, Vec<T>, Vec<T>)
267 impl<T> VecPerParamSpace<T> {
268 pub fn empty() -> VecPerParamSpace<T> {
270 vecs: (Vec::new(), Vec::new(), Vec::new())
274 pub fn params_from_type(types: Vec<T>) -> VecPerParamSpace<T> {
275 VecPerParamSpace::empty().with_vec(TypeSpace, types)
278 pub fn new(t: Vec<T>, s: Vec<T>, f: Vec<T>) -> VecPerParamSpace<T> {
284 pub fn sort(t: Vec<T>, space: |&T| -> ParamSpace) -> VecPerParamSpace<T> {
285 let mut result = VecPerParamSpace::empty();
286 for t in t.move_iter() {
287 result.push(space(&t), t);
292 pub fn push(&mut self, space: ParamSpace, value: T) {
293 self.get_mut_vec(space).push(value);
296 pub fn get_self<'a>(&'a self) -> Option<&'a T> {
297 let v = self.get_vec(SelfSpace);
298 assert!(v.len() <= 1);
299 if v.len() == 0 { None } else { Some(v.get(0)) }
302 pub fn len(&self, space: ParamSpace) -> uint {
303 self.get_vec(space).len()
306 pub fn get_vec<'a>(&'a self, space: ParamSpace) -> &'a Vec<T> {
307 self.vecs.get(space as uint).unwrap()
310 pub fn get_mut_vec<'a>(&'a mut self, space: ParamSpace) -> &'a mut Vec<T> {
311 self.vecs.get_mut(space as uint).unwrap()
314 pub fn opt_get<'a>(&'a self,
318 let v = self.get_vec(space);
319 if index < v.len() { Some(v.get(index)) } else { None }
322 pub fn get<'a>(&'a self, space: ParamSpace, index: uint) -> &'a T {
323 self.get_vec(space).get(index)
326 pub fn get_mut<'a>(&'a mut self,
328 index: uint) -> &'a mut T {
329 self.get_mut_vec(space).get_mut(index)
332 pub fn iter<'a>(&'a self) -> Chain<Items<'a,T>,
335 let (ref r, ref s, ref f) = self.vecs;
336 r.iter().chain(s.iter().chain(f.iter()))
339 pub fn all_vecs(&self, pred: |&Vec<T>| -> bool) -> bool {
340 self.vecs.iter().all(pred)
343 pub fn all(&self, pred: |&T| -> bool) -> bool {
344 self.iter().all(pred)
347 pub fn any(&self, pred: |&T| -> bool) -> bool {
348 self.iter().any(pred)
351 pub fn is_empty(&self) -> bool {
352 self.all_vecs(|v| v.is_empty())
355 pub fn map<U>(&self, pred: |&T| -> U) -> VecPerParamSpace<U> {
356 VecPerParamSpace::new(self.vecs.ref0().iter().map(|p| pred(p)).collect(),
357 self.vecs.ref1().iter().map(|p| pred(p)).collect(),
358 self.vecs.ref2().iter().map(|p| pred(p)).collect())
361 pub fn map_rev<U>(&self, pred: |&T| -> U) -> VecPerParamSpace<U> {
363 * Executes the map but in reverse order. For hacky reasons, we rely
366 * FIXME(#5527) -- order of eval becomes irrelevant with newer
367 * trait reform, which features an idempotent algorithm that
368 * can be run to a fixed point
371 let mut fns: Vec<U> = self.vecs.ref2().iter().rev().map(|p| pred(p)).collect();
373 // NB: Calling foo.rev().map().rev() causes the calls to map
374 // to occur in the wrong order. This was somewhat surprising
375 // to me, though it makes total sense.
378 let mut selfs: Vec<U> = self.vecs.ref1().iter().rev().map(|p| pred(p)).collect();
380 let mut tys: Vec<U> = self.vecs.ref0().iter().rev().map(|p| pred(p)).collect();
382 VecPerParamSpace::new(tys, selfs, fns)
385 pub fn split(self) -> (Vec<T>, Vec<T>, Vec<T>) {
389 pub fn with_vec(mut self, space: ParamSpace, vec: Vec<T>)
390 -> VecPerParamSpace<T>
392 assert!(self.get_vec(space).is_empty());
393 *self.get_mut_vec(space) = vec;
398 ///////////////////////////////////////////////////////////////////////////
399 // Public trait `Subst`
401 // Just call `foo.subst(tcx, substs)` to perform a substitution across
402 // `foo`. Or use `foo.subst_spanned(tcx, substs, Some(span))` when
403 // there is more information available (for better errors).
406 fn subst(&self, tcx: &ty::ctxt, substs: &Substs) -> Self {
407 self.subst_spanned(tcx, substs, None)
410 fn subst_spanned(&self, tcx: &ty::ctxt,
416 impl<T:TypeFoldable> Subst for T {
417 fn subst_spanned(&self,
423 let mut folder = SubstFolder { tcx: tcx,
428 (*self).fold_with(&mut folder)
432 ///////////////////////////////////////////////////////////////////////////
433 // The actual substitution engine itself is a type folder.
435 struct SubstFolder<'a> {
439 // The location for which the substitution is performed, if available.
442 // The root type that is being substituted, if available.
443 root_ty: Option<ty::t>,
445 // Depth of type stack
446 ty_stack_depth: uint,
449 impl<'a> TypeFolder for SubstFolder<'a> {
450 fn tcx<'a>(&'a self) -> &'a ty::ctxt { self.tcx }
452 fn fold_region(&mut self, r: ty::Region) -> ty::Region {
453 // Note: This routine only handles regions that are bound on
454 // type declarations and other outer declarations, not those
455 // bound in *fn types*. Region substitution of the bound
456 // regions that appear in a function signature is done using
457 // the specialized routine
458 // `middle::typeck::check::regionmanip::replace_late_regions_in_fn_sig()`.
460 ty::ReEarlyBound(_, space, i, _) => {
461 match self.substs.regions {
462 ErasedRegions => ty::ReStatic,
463 NonerasedRegions(ref regions) => *regions.get(space, i),
470 fn fold_ty(&mut self, t: ty::t) -> ty::t {
471 if !ty::type_needs_subst(t) {
475 // track the root type we were asked to substitute
476 let depth = self.ty_stack_depth;
478 self.root_ty = Some(t);
480 self.ty_stack_depth += 1;
482 let t1 = match ty::get(t).sty {
484 check(self, t, self.substs.types.opt_get(p.space, p.idx))
487 ty_fold::super_fold_ty(self, t)
491 assert_eq!(depth + 1, self.ty_stack_depth);
492 self.ty_stack_depth -= 1;
499 fn check(this: &SubstFolder,
501 opt_ty: Option<&ty::t>)
506 let span = this.span.unwrap_or(DUMMY_SP);
507 this.tcx().sess.span_bug(
509 format!("Type parameter {} out of range \
510 when substituting (root type={})",
511 source_ty.repr(this.tcx()),
512 this.root_ty.repr(this.tcx())).as_slice());