include/llvm/ADT/ImmutableSet.h

   1 //===--- ImmutableSet.h - Immutable (functional) set interface --*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file defines the ImutAVLTree and ImmutableSet classes.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef LLVM_ADT_IMMUTABLESET_H
  14 #define LLVM_ADT_IMMUTABLESET_H
  15
  16 #include "llvm/ADT/DenseMap.h"
  17 #include "llvm/ADT/FoldingSet.h"
  18 #include "llvm/ADT/SmallVector.h"
  19 #include "llvm/ADT/iterator.h"
  20 #include "llvm/Support/Allocator.h"
  21 #include "llvm/Support/ErrorHandling.h"
  22 #include <cassert>
  23 #include <cstdint>
  24 #include <functional>
  25 #include <iterator>
  26 #include <new>
  27 #include <vector>
  28
  29 namespace llvm {
  30
  31 //===----------------------------------------------------------------------===//
  32 // Immutable AVL-Tree Definition.
  33 //===----------------------------------------------------------------------===//
  34
  35 template <typename ImutInfo> class ImutAVLFactory;
  36 template <typename ImutInfo> class ImutIntervalAVLFactory;
  37 template <typename ImutInfo> class ImutAVLTreeInOrderIterator;
  38 template <typename ImutInfo> class ImutAVLTreeGenericIterator;
  39
  40 template <typename ImutInfo >
  41 class ImutAVLTree {
  42 public:
  43   using key_type_ref = typename ImutInfo::key_type_ref;
  44   using value_type = typename ImutInfo::value_type;
  45   using value_type_ref = typename ImutInfo::value_type_ref;
  46   using Factory = ImutAVLFactory<ImutInfo>;
  47   using iterator = ImutAVLTreeInOrderIterator<ImutInfo>;
  48
  49   friend class ImutAVLFactory<ImutInfo>;
  50   friend class ImutIntervalAVLFactory<ImutInfo>;
  51   friend class ImutAVLTreeGenericIterator<ImutInfo>;
  52
  53   //===----------------------------------------------------===//
  54   // Public Interface.
  55   //===----------------------------------------------------===//
  56
  57   /// Return a pointer to the left subtree.  This value
  58   ///  is NULL if there is no left subtree.
  59   ImutAVLTree *getLeft() const { return left; }
  60
  61   /// Return a pointer to the right subtree.  This value is
  62   ///  NULL if there is no right subtree.
  63   ImutAVLTree *getRight() const { return right; }
  64
  65   /// getHeight - Returns the height of the tree.  A tree with no subtrees
  66   ///  has a height of 1.
  67   unsigned getHeight() const { return height; }
  68
  69   /// getValue - Returns the data value associated with the tree node.
  70   const value_type& getValue() const { return value; }
  71
  72   /// find - Finds the subtree associated with the specified key value.
  73   ///  This method returns NULL if no matching subtree is found.
  74   ImutAVLTree* find(key_type_ref K) {
  75     ImutAVLTree *T = this;
  76     while (T) {
  77       key_type_ref CurrentKey = ImutInfo::KeyOfValue(T->getValue());
  78       if (ImutInfo::isEqual(K,CurrentKey))
  79         return T;
  80       else if (ImutInfo::isLess(K,CurrentKey))
  81         T = T->getLeft();
  82       else
  83         T = T->getRight();
  84     }
  85     return nullptr;
  86   }
  87
  88   /// getMaxElement - Find the subtree associated with the highest ranged
  89   ///  key value.
  90   ImutAVLTree* getMaxElement() {
  91     ImutAVLTree *T = this;
  92     ImutAVLTree *Right = T->getRight();
  93     while (Right) { T = Right; Right = T->getRight(); }
  94     return T;
  95   }
  96
  97   /// size - Returns the number of nodes in the tree, which includes
  98   ///  both leaves and non-leaf nodes.
  99   unsigned size() const {
 100     unsigned n = 1;
 101     if (const ImutAVLTree* L = getLeft())
 102       n += L->size();
 103     if (const ImutAVLTree* R = getRight())
 104       n += R->size();
 105     return n;
 106   }
 107
 108   /// begin - Returns an iterator that iterates over the nodes of the tree
 109   ///  in an inorder traversal.  The returned iterator thus refers to the
 110   ///  the tree node with the minimum data element.
 111   iterator begin() const { return iterator(this); }
 112
 113   /// end - Returns an iterator for the tree that denotes the end of an
 114   ///  inorder traversal.
 115   iterator end() const { return iterator(); }
 116
 117   bool isElementEqual(value_type_ref V) const {
 118     // Compare the keys.
 119     if (!ImutInfo::isEqual(ImutInfo::KeyOfValue(getValue()),
 120                            ImutInfo::KeyOfValue(V)))
 121       return false;
 122
 123     // Also compare the data values.
 124     if (!ImutInfo::isDataEqual(ImutInfo::DataOfValue(getValue()),
 125                                ImutInfo::DataOfValue(V)))
 126       return false;
 127
 128     return true;
 129   }
 130
 131   bool isElementEqual(const ImutAVLTree* RHS) const {
 132     return isElementEqual(RHS->getValue());
 133   }
 134
 135   /// isEqual - Compares two trees for structural equality and returns true
 136   ///   if they are equal.  This worst case performance of this operation is
 137   //    linear in the sizes of the trees.
 138   bool isEqual(const ImutAVLTree& RHS) const {
 139     if (&RHS == this)
 140       return true;
 141
 142     iterator LItr = begin(), LEnd = end();
 143     iterator RItr = RHS.begin(), REnd = RHS.end();
 144
 145     while (LItr != LEnd && RItr != REnd) {
 146       if (&*LItr == &*RItr) {
 147         LItr.skipSubTree();
 148         RItr.skipSubTree();
 149         continue;
 150       }
 151
 152       if (!LItr->isElementEqual(&*RItr))
 153         return false;
 154
 155       ++LItr;
 156       ++RItr;
 157     }
 158
 159     return LItr == LEnd && RItr == REnd;
 160   }
 161
 162   /// isNotEqual - Compares two trees for structural inequality.  Performance
 163   ///  is the same is isEqual.
 164   bool isNotEqual(const ImutAVLTree& RHS) const { return !isEqual(RHS); }
 165
 166   /// contains - Returns true if this tree contains a subtree (node) that
 167   ///  has an data element that matches the specified key.  Complexity
 168   ///  is logarithmic in the size of the tree.
 169   bool contains(key_type_ref K) { return (bool) find(K); }
 170
 171   /// foreach - A member template the accepts invokes operator() on a functor
 172   ///  object (specifed by Callback) for every node/subtree in the tree.
 173   ///  Nodes are visited using an inorder traversal.
 174   template <typename Callback>
 175   void foreach(Callback& C) {
 176     if (ImutAVLTree* L = getLeft())
 177       L->foreach(C);
 178
 179     C(value);
 180
 181     if (ImutAVLTree* R = getRight())
 182       R->foreach(C);
 183   }
 184
 185   /// validateTree - A utility method that checks that the balancing and
 186   ///  ordering invariants of the tree are satisifed.  It is a recursive
 187   ///  method that returns the height of the tree, which is then consumed
 188   ///  by the enclosing validateTree call.  External callers should ignore the
 189   ///  return value.  An invalid tree will cause an assertion to fire in
 190   ///  a debug build.
 191   unsigned validateTree() const {
 192     unsigned HL = getLeft() ? getLeft()->validateTree() : 0;
 193     unsigned HR = getRight() ? getRight()->validateTree() : 0;
 194     (void) HL;
 195     (void) HR;
 196
 197     assert(getHeight() == ( HL > HR ? HL : HR ) + 1
 198             && "Height calculation wrong");
 199
 200     assert((HL > HR ? HL-HR : HR-HL) <= 2
 201            && "Balancing invariant violated");
 202
 203     assert((!getLeft() ||
 204             ImutInfo::isLess(ImutInfo::KeyOfValue(getLeft()->getValue()),
 205                              ImutInfo::KeyOfValue(getValue()))) &&
 206            "Value in left child is not less that current value");
 207
 208
 209     assert(!(getRight() ||
 210              ImutInfo::isLess(ImutInfo::KeyOfValue(getValue()),
 211                               ImutInfo::KeyOfValue(getRight()->getValue()))) &&
 212            "Current value is not less that value of right child");
 213
 214     return getHeight();
 215   }
 216
 217   //===----------------------------------------------------===//
 218   // Internal values.
 219   //===----------------------------------------------------===//
 220
 221 private:
 222   Factory *factory;
 223   ImutAVLTree *left;
 224   ImutAVLTree *right;
 225   ImutAVLTree *prev = nullptr;
 226   ImutAVLTree *next = nullptr;
 227
 228   unsigned height : 28;
 229   bool IsMutable : 1;
 230   bool IsDigestCached : 1;
 231   bool IsCanonicalized : 1;
 232
 233   value_type value;
 234   uint32_t digest = 0;
 235   uint32_t refCount = 0;
 236
 237   //===----------------------------------------------------===//
 238   // Internal methods (node manipulation; used by Factory).
 239   //===----------------------------------------------------===//
 240
 241 private:
 242   /// ImutAVLTree - Internal constructor that is only called by
 243   ///   ImutAVLFactory.
 244   ImutAVLTree(Factory *f, ImutAVLTree* l, ImutAVLTree* r, value_type_ref v,
 245               unsigned height)
 246     : factory(f), left(l), right(r), height(height), IsMutable(true),
 247       IsDigestCached(false), IsCanonicalized(false), value(v)
 248   {
 249     if (left) left->retain();
 250     if (right) right->retain();
 251   }
 252
 253   /// isMutable - Returns true if the left and right subtree references
 254   ///  (as well as height) can be changed.  If this method returns false,
 255   ///  the tree is truly immutable.  Trees returned from an ImutAVLFactory
 256   ///  object should always have this method return true.  Further, if this
 257   ///  method returns false for an instance of ImutAVLTree, all subtrees
 258   ///  will also have this method return false.  The converse is not true.
 259   bool isMutable() const { return IsMutable; }
 260
 261   /// hasCachedDigest - Returns true if the digest for this tree is cached.
 262   ///  This can only be true if the tree is immutable.
 263   bool hasCachedDigest() const { return IsDigestCached; }
 264
 265   //===----------------------------------------------------===//
 266   // Mutating operations.  A tree root can be manipulated as
 267   // long as its reference has not "escaped" from internal
 268   // methods of a factory object (see below).  When a tree
 269   // pointer is externally viewable by client code, the
 270   // internal "mutable bit" is cleared to mark the tree
 271   // immutable.  Note that a tree that still has its mutable
 272   // bit set may have children (subtrees) that are themselves
 273   // immutable.
 274   //===----------------------------------------------------===//
 275
 276   /// markImmutable - Clears the mutable flag for a tree.  After this happens,
 277   ///   it is an error to call setLeft(), setRight(), and setHeight().
 278   void markImmutable() {
 279     assert(isMutable() && "Mutable flag already removed.");
 280     IsMutable = false;
 281   }
 282
 283   /// markedCachedDigest - Clears the NoCachedDigest flag for a tree.
 284   void markedCachedDigest() {
 285     assert(!hasCachedDigest() && "NoCachedDigest flag already removed.");
 286     IsDigestCached = true;
 287   }
 288
 289   /// setHeight - Changes the height of the tree.  Used internally by
 290   ///  ImutAVLFactory.
 291   void setHeight(unsigned h) {
 292     assert(isMutable() && "Only a mutable tree can have its height changed.");
 293     height = h;
 294   }
 295
 296   static uint32_t computeDigest(ImutAVLTree *L, ImutAVLTree *R,
 297                                 value_type_ref V) {
 298     uint32_t digest = 0;
 299
 300     if (L)
 301       digest += L->computeDigest();
 302
 303     // Compute digest of stored data.
 304     FoldingSetNodeID ID;
 305     ImutInfo::Profile(ID,V);
 306     digest += ID.ComputeHash();
 307
 308     if (R)
 309       digest += R->computeDigest();
 310
 311     return digest;
 312   }
 313
 314   uint32_t computeDigest() {
 315     // Check the lowest bit to determine if digest has actually been
 316     // pre-computed.
 317     if (hasCachedDigest())
 318       return digest;
 319
 320     uint32_t X = computeDigest(getLeft(), getRight(), getValue());
 321     digest = X;
 322     markedCachedDigest();
 323     return X;
 324   }
 325
 326   //===----------------------------------------------------===//
 327   // Reference count operations.
 328   //===----------------------------------------------------===//
 329
 330 public:
 331   void retain() { ++refCount; }
 332
 333   void release() {
 334     assert(refCount > 0);
 335     if (--refCount == 0)
 336       destroy();
 337   }
 338
 339   void destroy() {
 340     if (left)
 341       left->release();
 342     if (right)
 343       right->release();
 344     if (IsCanonicalized) {
 345       if (next)
 346         next->prev = prev;
 347
 348       if (prev)
 349         prev->next = next;
 350       else
 351         factory->Cache[factory->maskCacheIndex(computeDigest())] = next;
 352     }
 353
 354     // We need to clear the mutability bit in case we are
 355     // destroying the node as part of a sweep in ImutAVLFactory::recoverNodes().
 356     IsMutable = false;
 357     factory->freeNodes.push_back(this);
 358   }
 359 };
 360
 361 //===----------------------------------------------------------------------===//
 362 // Immutable AVL-Tree Factory class.
 363 //===----------------------------------------------------------------------===//
 364
 365 template <typename ImutInfo >
 366 class ImutAVLFactory {
 367   friend class ImutAVLTree<ImutInfo>;
 368
 369   using TreeTy = ImutAVLTree<ImutInfo>;
 370   using value_type_ref = typename TreeTy::value_type_ref;
 371   using key_type_ref = typename TreeTy::key_type_ref;
 372   using CacheTy = DenseMap<unsigned, TreeTy*>;
 373
 374   CacheTy Cache;
 375   uintptr_t Allocator;
 376   std::vector<TreeTy*> createdNodes;
 377   std::vector<TreeTy*> freeNodes;
 378
 379   bool ownsAllocator() const {
 380     return (Allocator & 0x1) == 0;
 381   }
 382
 383   BumpPtrAllocator& getAllocator() const {
 384     return *reinterpret_cast<BumpPtrAllocator*>(Allocator & ~0x1);
 385   }
 386
 387   //===--------------------------------------------------===//
 388   // Public interface.
 389   //===--------------------------------------------------===//
 390
 391 public:
 392   ImutAVLFactory()
 393     : Allocator(reinterpret_cast<uintptr_t>(new BumpPtrAllocator())) {}
 394
 395   ImutAVLFactory(BumpPtrAllocator& Alloc)
 396     : Allocator(reinterpret_cast<uintptr_t>(&Alloc) | 0x1) {}
 397
 398   ~ImutAVLFactory() {
 399     if (ownsAllocator()) delete &getAllocator();
 400   }
 401
 402   TreeTy* add(TreeTy* T, value_type_ref V) {
 403     T = add_internal(V,T);
 404     markImmutable(T);
 405     recoverNodes();
 406     return T;
 407   }
 408
 409   TreeTy* remove(TreeTy* T, key_type_ref V) {
 410     T = remove_internal(V,T);
 411     markImmutable(T);
 412     recoverNodes();
 413     return T;
 414   }
 415
 416   TreeTy* getEmptyTree() const { return nullptr; }
 417
 418 protected:
 419   //===--------------------------------------------------===//
 420   // A bunch of quick helper functions used for reasoning
 421   // about the properties of trees and their children.
 422   // These have succinct names so that the balancing code
 423   // is as terse (and readable) as possible.
 424   //===--------------------------------------------------===//
 425
 426   bool            isEmpty(TreeTy* T) const { return !T; }
 427   unsigned        getHeight(TreeTy* T) const { return T ? T->getHeight() : 0; }
 428   TreeTy*         getLeft(TreeTy* T) const { return T->getLeft(); }
 429   TreeTy*         getRight(TreeTy* T) const { return T->getRight(); }
 430   value_type_ref  getValue(TreeTy* T) const { return T->value; }
 431
 432   // Make sure the index is not the Tombstone or Entry key of the DenseMap.
 433   static unsigned maskCacheIndex(unsigned I) { return (I & ~0x02); }
 434
 435   unsigned incrementHeight(TreeTy* L, TreeTy* R) const {
 436     unsigned hl = getHeight(L);
 437     unsigned hr = getHeight(R);
 438     return (hl > hr ? hl : hr) + 1;
 439   }
 440
 441   static bool compareTreeWithSection(TreeTy* T,
 442                                      typename TreeTy::iterator& TI,
 443                                      typename TreeTy::iterator& TE) {
 444     typename TreeTy::iterator I = T->begin(), E = T->end();
 445     for ( ; I!=E ; ++I, ++TI) {
 446       if (TI == TE || !I->isElementEqual(&*TI))
 447         return false;
 448     }
 449     return true;
 450   }
 451
 452   //===--------------------------------------------------===//
 453   // "createNode" is used to generate new tree roots that link
 454   // to other trees.  The functon may also simply move links
 455   // in an existing root if that root is still marked mutable.
 456   // This is necessary because otherwise our balancing code
 457   // would leak memory as it would create nodes that are
 458   // then discarded later before the finished tree is
 459   // returned to the caller.
 460   //===--------------------------------------------------===//
 461
 462   TreeTy* createNode(TreeTy* L, value_type_ref V, TreeTy* R) {
 463     BumpPtrAllocator& A = getAllocator();
 464     TreeTy* T;
 465     if (!freeNodes.empty()) {
 466       T = freeNodes.back();
 467       freeNodes.pop_back();
 468       assert(T != L);
 469       assert(T != R);
 470     } else {
 471       T = (TreeTy*) A.Allocate<TreeTy>();
 472     }
 473     new (T) TreeTy(this, L, R, V, incrementHeight(L,R));
 474     createdNodes.push_back(T);
 475     return T;
 476   }
 477
 478   TreeTy* createNode(TreeTy* newLeft, TreeTy* oldTree, TreeTy* newRight) {
 479     return createNode(newLeft, getValue(oldTree), newRight);
 480   }
 481
 482   void recoverNodes() {
 483     for (unsigned i = 0, n = createdNodes.size(); i < n; ++i) {
 484       TreeTy *N = createdNodes[i];
 485       if (N->isMutable() && N->refCount == 0)
 486         N->destroy();
 487     }
 488     createdNodes.clear();
 489   }
 490
 491   /// balanceTree - Used by add_internal and remove_internal to
 492   ///  balance a newly created tree.
 493   TreeTy* balanceTree(TreeTy* L, value_type_ref V, TreeTy* R) {
 494     unsigned hl = getHeight(L);
 495     unsigned hr = getHeight(R);
 496
 497     if (hl > hr + 2) {
 498       assert(!isEmpty(L) && "Left tree cannot be empty to have a height >= 2");
 499
 500       TreeTy *LL = getLeft(L);
 501       TreeTy *LR = getRight(L);
 502
 503       if (getHeight(LL) >= getHeight(LR))
 504         return createNode(LL, L, createNode(LR,V,R));
 505
 506       assert(!isEmpty(LR) && "LR cannot be empty because it has a height >= 1");
 507
 508       TreeTy *LRL = getLeft(LR);
 509       TreeTy *LRR = getRight(LR);
 510
 511       return createNode(createNode(LL,L,LRL), LR, createNode(LRR,V,R));
 512     }
 513
 514     if (hr > hl + 2) {
 515       assert(!isEmpty(R) && "Right tree cannot be empty to have a height >= 2");
 516
 517       TreeTy *RL = getLeft(R);
 518       TreeTy *RR = getRight(R);
 519
 520       if (getHeight(RR) >= getHeight(RL))
 521         return createNode(createNode(L,V,RL), R, RR);
 522
 523       assert(!isEmpty(RL) && "RL cannot be empty because it has a height >= 1");
 524
 525       TreeTy *RLL = getLeft(RL);
 526       TreeTy *RLR = getRight(RL);
 527
 528       return createNode(createNode(L,V,RLL), RL, createNode(RLR,R,RR));
 529     }
 530
 531     return createNode(L,V,R);
 532   }
 533
 534   /// add_internal - Creates a new tree that includes the specified
 535   ///  data and the data from the original tree.  If the original tree
 536   ///  already contained the data item, the original tree is returned.
 537   TreeTy* add_internal(value_type_ref V, TreeTy* T) {
 538     if (isEmpty(T))
 539       return createNode(T, V, T);
 540     assert(!T->isMutable());
 541
 542     key_type_ref K = ImutInfo::KeyOfValue(V);
 543     key_type_ref KCurrent = ImutInfo::KeyOfValue(getValue(T));
 544
 545     if (ImutInfo::isEqual(K,KCurrent))
 546       return createNode(getLeft(T), V, getRight(T));
 547     else if (ImutInfo::isLess(K,KCurrent))
 548       return balanceTree(add_internal(V, getLeft(T)), getValue(T), getRight(T));
 549     else
 550       return balanceTree(getLeft(T), getValue(T), add_internal(V, getRight(T)));
 551   }
 552
 553   /// remove_internal - Creates a new tree that includes all the data
 554   ///  from the original tree except the specified data.  If the
 555   ///  specified data did not exist in the original tree, the original
 556   ///  tree is returned.
 557   TreeTy* remove_internal(key_type_ref K, TreeTy* T) {
 558     if (isEmpty(T))
 559       return T;
 560
 561     assert(!T->isMutable());
 562
 563     key_type_ref KCurrent = ImutInfo::KeyOfValue(getValue(T));
 564
 565     if (ImutInfo::isEqual(K,KCurrent)) {
 566       return combineTrees(getLeft(T), getRight(T));
 567     } else if (ImutInfo::isLess(K,KCurrent)) {
 568       return balanceTree(remove_internal(K, getLeft(T)),
 569                                             getValue(T), getRight(T));
 570     } else {
 571       return balanceTree(getLeft(T), getValue(T),
 572                          remove_internal(K, getRight(T)));
 573     }
 574   }
 575
 576   TreeTy* combineTrees(TreeTy* L, TreeTy* R) {
 577     if (isEmpty(L))
 578       return R;
 579     if (isEmpty(R))
 580       return L;
 581     TreeTy* OldNode;
 582     TreeTy* newRight = removeMinBinding(R,OldNode);
 583     return balanceTree(L, getValue(OldNode), newRight);
 584   }
 585
 586   TreeTy* removeMinBinding(TreeTy* T, TreeTy*& Noderemoved) {
 587     assert(!isEmpty(T));
 588     if (isEmpty(getLeft(T))) {
 589       Noderemoved = T;
 590       return getRight(T);
 591     }
 592     return balanceTree(removeMinBinding(getLeft(T), Noderemoved),
 593                        getValue(T), getRight(T));
 594   }
 595
 596   /// markImmutable - Clears the mutable bits of a root and all of its
 597   ///  descendants.
 598   void markImmutable(TreeTy* T) {
 599     if (!T || !T->isMutable())
 600       return;
 601     T->markImmutable();
 602     markImmutable(getLeft(T));
 603     markImmutable(getRight(T));
 604   }
 605
 606 public:
 607   TreeTy *getCanonicalTree(TreeTy *TNew) {
 608     if (!TNew)
 609       return nullptr;
 610
 611     if (TNew->IsCanonicalized)
 612       return TNew;
 613
 614     // Search the hashtable for another tree with the same digest, and
 615     // if find a collision compare those trees by their contents.
 616     unsigned digest = TNew->computeDigest();
 617     TreeTy *&entry = Cache[maskCacheIndex(digest)];
 618     do {
 619       if (!entry)
 620         break;
 621       for (TreeTy *T = entry ; T != nullptr; T = T->next) {
 622         // Compare the Contents('T') with Contents('TNew')
 623         typename TreeTy::iterator TI = T->begin(), TE = T->end();
 624         if (!compareTreeWithSection(TNew, TI, TE))
 625           continue;
 626         if (TI != TE)
 627           continue; // T has more contents than TNew.
 628         // Trees did match!  Return 'T'.
 629         if (TNew->refCount == 0)
 630           TNew->destroy();
 631         return T;
 632       }
 633       entry->prev = TNew;
 634       TNew->next = entry;
 635     }
 636     while (false);
 637
 638     entry = TNew;
 639     TNew->IsCanonicalized = true;
 640     return TNew;
 641   }
 642 };
 643
 644 //===----------------------------------------------------------------------===//
 645 // Immutable AVL-Tree Iterators.
 646 //===----------------------------------------------------------------------===//
 647
 648 template <typename ImutInfo>
 649 class ImutAVLTreeGenericIterator
 650     : public std::iterator<std::bidirectional_iterator_tag,
 651                            ImutAVLTree<ImutInfo>> {
 652   SmallVector<uintptr_t,20> stack;
 653
 654 public:
 655   enum VisitFlag { VisitedNone=0x0, VisitedLeft=0x1, VisitedRight=0x3,
 656                    Flags=0x3 };
 657
 658   using TreeTy = ImutAVLTree<ImutInfo>;
 659
 660   ImutAVLTreeGenericIterator() = default;
 661   ImutAVLTreeGenericIterator(const TreeTy *Root) {
 662     if (Root) stack.push_back(reinterpret_cast<uintptr_t>(Root));
 663   }
 664
 665   TreeTy &operator*() const {
 666     assert(!stack.empty());
 667     return *reinterpret_cast<TreeTy *>(stack.back() & ~Flags);
 668   }
 669   TreeTy *operator->() const { return &*this; }
 670
 671   uintptr_t getVisitState() const {
 672     assert(!stack.empty());
 673     return stack.back() & Flags;
 674   }
 675
 676   bool atEnd() const { return stack.empty(); }
 677
 678   bool atBeginning() const {
 679     return stack.size() == 1 && getVisitState() == VisitedNone;
 680   }
 681
 682   void skipToParent() {
 683     assert(!stack.empty());
 684     stack.pop_back();
 685     if (stack.empty())
 686       return;
 687     switch (getVisitState()) {
 688       case VisitedNone:
 689         stack.back() |= VisitedLeft;
 690         break;
 691       case VisitedLeft:
 692         stack.back() |= VisitedRight;
 693         break;
 694       default:
 695         llvm_unreachable("Unreachable.");
 696     }
 697   }
 698
 699   bool operator==(const ImutAVLTreeGenericIterator &x) const {
 700     return stack == x.stack;
 701   }
 702
 703   bool operator!=(const ImutAVLTreeGenericIterator &x) const {
 704     return !(*this == x);
 705   }
 706
 707   ImutAVLTreeGenericIterator &operator++() {
 708     assert(!stack.empty());
 709     TreeTy* Current = reinterpret_cast<TreeTy*>(stack.back() & ~Flags);
 710     assert(Current);
 711     switch (getVisitState()) {
 712       case VisitedNone:
 713         if (TreeTy* L = Current->getLeft())
 714           stack.push_back(reinterpret_cast<uintptr_t>(L));
 715         else
 716           stack.back() |= VisitedLeft;
 717         break;
 718       case VisitedLeft:
 719         if (TreeTy* R = Current->getRight())
 720           stack.push_back(reinterpret_cast<uintptr_t>(R));
 721         else
 722           stack.back() |= VisitedRight;
 723         break;
 724       case VisitedRight:
 725         skipToParent();
 726         break;
 727       default:
 728         llvm_unreachable("Unreachable.");
 729     }
 730     return *this;
 731   }
 732
 733   ImutAVLTreeGenericIterator &operator--() {
 734     assert(!stack.empty());
 735     TreeTy* Current = reinterpret_cast<TreeTy*>(stack.back() & ~Flags);
 736     assert(Current);
 737     switch (getVisitState()) {
 738       case VisitedNone:
 739         stack.pop_back();
 740         break;
 741       case VisitedLeft:
 742         stack.back() &= ~Flags; // Set state to "VisitedNone."
 743         if (TreeTy* L = Current->getLeft())
 744           stack.push_back(reinterpret_cast<uintptr_t>(L) | VisitedRight);
 745         break;
 746       case VisitedRight:
 747         stack.back() &= ~Flags;
 748         stack.back() |= VisitedLeft;
 749         if (TreeTy* R = Current->getRight())
 750           stack.push_back(reinterpret_cast<uintptr_t>(R) | VisitedRight);
 751         break;
 752       default:
 753         llvm_unreachable("Unreachable.");
 754     }
 755     return *this;
 756   }
 757 };
 758
 759 template <typename ImutInfo>
 760 class ImutAVLTreeInOrderIterator
 761     : public std::iterator<std::bidirectional_iterator_tag,
 762                            ImutAVLTree<ImutInfo>> {
 763   using InternalIteratorTy = ImutAVLTreeGenericIterator<ImutInfo>;
 764
 765   InternalIteratorTy InternalItr;
 766
 767 public:
 768   using TreeTy = ImutAVLTree<ImutInfo>;
 769
 770   ImutAVLTreeInOrderIterator(const TreeTy* Root) : InternalItr(Root) {
 771     if (Root)
 772       ++*this; // Advance to first element.
 773   }
 774
 775   ImutAVLTreeInOrderIterator() : InternalItr() {}
 776
 777   bool operator==(const ImutAVLTreeInOrderIterator &x) const {
 778     return InternalItr == x.InternalItr;
 779   }
 780
 781   bool operator!=(const ImutAVLTreeInOrderIterator &x) const {
 782     return !(*this == x);
 783   }
 784
 785   TreeTy &operator*() const { return *InternalItr; }
 786   TreeTy *operator->() const { return &*InternalItr; }
 787
 788   ImutAVLTreeInOrderIterator &operator++() {
 789     do ++InternalItr;
 790     while (!InternalItr.atEnd() &&
 791            InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft);
 792
 793     return *this;
 794   }
 795
 796   ImutAVLTreeInOrderIterator &operator--() {
 797     do --InternalItr;
 798     while (!InternalItr.atBeginning() &&
 799            InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft);
 800
 801     return *this;
 802   }
 803
 804   void skipSubTree() {
 805     InternalItr.skipToParent();
 806
 807     while (!InternalItr.atEnd() &&
 808            InternalItr.getVisitState() != InternalIteratorTy::VisitedLeft)
 809       ++InternalItr;
 810   }
 811 };
 812
 813 /// Generic iterator that wraps a T::TreeTy::iterator and exposes
 814 /// iterator::getValue() on dereference.
 815 template <typename T>
 816 struct ImutAVLValueIterator
 817     : iterator_adaptor_base<
 818           ImutAVLValueIterator<T>, typename T::TreeTy::iterator,
 819           typename std::iterator_traits<
 820               typename T::TreeTy::iterator>::iterator_category,
 821           const typename T::value_type> {
 822   ImutAVLValueIterator() = default;
 823   explicit ImutAVLValueIterator(typename T::TreeTy *Tree)
 824       : ImutAVLValueIterator::iterator_adaptor_base(Tree) {}
 825
 826   typename ImutAVLValueIterator::reference operator*() const {
 827     return this->I->getValue();
 828   }
 829 };
 830
 831 //===----------------------------------------------------------------------===//
 832 // Trait classes for Profile information.
 833 //===----------------------------------------------------------------------===//
 834
 835 /// Generic profile template.  The default behavior is to invoke the
 836 /// profile method of an object.  Specializations for primitive integers
 837 /// and generic handling of pointers is done below.
 838 template <typename T>
 839 struct ImutProfileInfo {
 840   using value_type = const T;
 841   using value_type_ref = const T&;
 842
 843   static void Profile(FoldingSetNodeID &ID, value_type_ref X) {
 844     FoldingSetTrait<T>::Profile(X,ID);
 845   }
 846 };
 847
 848 /// Profile traits for integers.
 849 template <typename T>
 850 struct ImutProfileInteger {
 851   using value_type = const T;
 852   using value_type_ref = const T&;
 853
 854   static void Profile(FoldingSetNodeID &ID, value_type_ref X) {
 855     ID.AddInteger(X);
 856   }
 857 };
 858
 859 #define PROFILE_INTEGER_INFO(X)\
 860 template<> struct ImutProfileInfo<X> : ImutProfileInteger<X> {};
 861
 862 PROFILE_INTEGER_INFO(char)
 863 PROFILE_INTEGER_INFO(unsigned char)
 864 PROFILE_INTEGER_INFO(short)
 865 PROFILE_INTEGER_INFO(unsigned short)
 866 PROFILE_INTEGER_INFO(unsigned)
 867 PROFILE_INTEGER_INFO(signed)
 868 PROFILE_INTEGER_INFO(long)
 869 PROFILE_INTEGER_INFO(unsigned long)
 870 PROFILE_INTEGER_INFO(long long)
 871 PROFILE_INTEGER_INFO(unsigned long long)
 872
 873 #undef PROFILE_INTEGER_INFO
 874
 875 /// Profile traits for booleans.
 876 template <>
 877 struct ImutProfileInfo<bool> {
 878   using value_type = const bool;
 879   using value_type_ref = const bool&;
 880
 881   static void Profile(FoldingSetNodeID &ID, value_type_ref X) {
 882     ID.AddBoolean(X);
 883   }
 884 };
 885
 886 /// Generic profile trait for pointer types.  We treat pointers as
 887 /// references to unique objects.
 888 template <typename T>
 889 struct ImutProfileInfo<T*> {
 890   using value_type = const T*;
 891   using value_type_ref = value_type;
 892
 893   static void Profile(FoldingSetNodeID &ID, value_type_ref X) {
 894     ID.AddPointer(X);
 895   }
 896 };
 897
 898 //===----------------------------------------------------------------------===//
 899 // Trait classes that contain element comparison operators and type
 900 //  definitions used by ImutAVLTree, ImmutableSet, and ImmutableMap.  These
 901 //  inherit from the profile traits (ImutProfileInfo) to include operations
 902 //  for element profiling.
 903 //===----------------------------------------------------------------------===//
 904
 905 /// ImutContainerInfo - Generic definition of comparison operations for
 906 ///   elements of immutable containers that defaults to using
 907 ///   std::equal_to<> and std::less<> to perform comparison of elements.
 908 template <typename T>
 909 struct ImutContainerInfo : public ImutProfileInfo<T> {
 910   using value_type = typename ImutProfileInfo<T>::value_type;
 911   using value_type_ref = typename ImutProfileInfo<T>::value_type_ref;
 912   using key_type = value_type;
 913   using key_type_ref = value_type_ref;
 914   using data_type = bool;
 915   using data_type_ref = bool;
 916
 917   static key_type_ref KeyOfValue(value_type_ref D) { return D; }
 918   static data_type_ref DataOfValue(value_type_ref) { return true; }
 919
 920   static bool isEqual(key_type_ref LHS, key_type_ref RHS) {
 921     return std::equal_to<key_type>()(LHS,RHS);
 922   }
 923
 924   static bool isLess(key_type_ref LHS, key_type_ref RHS) {
 925     return std::less<key_type>()(LHS,RHS);
 926   }
 927
 928   static bool isDataEqual(data_type_ref, data_type_ref) { return true; }
 929 };
 930
 931 /// ImutContainerInfo - Specialization for pointer values to treat pointers
 932 ///  as references to unique objects.  Pointers are thus compared by
 933 ///  their addresses.
 934 template <typename T>
 935 struct ImutContainerInfo<T*> : public ImutProfileInfo<T*> {
 936   using value_type = typename ImutProfileInfo<T*>::value_type;
 937   using value_type_ref = typename ImutProfileInfo<T*>::value_type_ref;
 938   using key_type = value_type;
 939   using key_type_ref = value_type_ref;
 940   using data_type = bool;
 941   using data_type_ref = bool;
 942
 943   static key_type_ref KeyOfValue(value_type_ref D) { return D; }
 944   static data_type_ref DataOfValue(value_type_ref) { return true; }
 945
 946   static bool isEqual(key_type_ref LHS, key_type_ref RHS) { return LHS == RHS; }
 947
 948   static bool isLess(key_type_ref LHS, key_type_ref RHS) { return LHS < RHS; }
 949
 950   static bool isDataEqual(data_type_ref, data_type_ref) { return true; }
 951 };
 952
 953 //===----------------------------------------------------------------------===//
 954 // Immutable Set
 955 //===----------------------------------------------------------------------===//
 956
 957 template <typename ValT, typename ValInfo = ImutContainerInfo<ValT>>
 958 class ImmutableSet {
 959 public:
 960   using value_type = typename ValInfo::value_type;
 961   using value_type_ref = typename ValInfo::value_type_ref;
 962   using TreeTy = ImutAVLTree<ValInfo>;
 963
 964 private:
 965   TreeTy *Root;
 966
 967 public:
 968   /// Constructs a set from a pointer to a tree root.  In general one
 969   /// should use a Factory object to create sets instead of directly
 970   /// invoking the constructor, but there are cases where make this
 971   /// constructor public is useful.
 972   explicit ImmutableSet(TreeTy* R) : Root(R) {
 973     if (Root) { Root->retain(); }
 974   }
 975
 976   ImmutableSet(const ImmutableSet &X) : Root(X.Root) {
 977     if (Root) { Root->retain(); }
 978   }
 979
 980   ~ImmutableSet() {
 981     if (Root) { Root->release(); }
 982   }
 983
 984   ImmutableSet &operator=(const ImmutableSet &X) {
 985     if (Root != X.Root) {
 986       if (X.Root) { X.Root->retain(); }
 987       if (Root) { Root->release(); }
 988       Root = X.Root;
 989     }
 990     return *this;
 991   }
 992
 993   class Factory {
 994     typename TreeTy::Factory F;
 995     const bool Canonicalize;
 996
 997   public:
 998     Factory(bool canonicalize = true)
 999       : Canonicalize(canonicalize) {}
1000
1001     Factory(BumpPtrAllocator& Alloc, bool canonicalize = true)
1002       : F(Alloc), Canonicalize(canonicalize) {}
1003
1004     Factory(const Factory& RHS) = delete;
1005     void operator=(const Factory& RHS) = delete;
1006
1007     /// getEmptySet - Returns an immutable set that contains no elements.
1008     ImmutableSet getEmptySet() {
1009       return ImmutableSet(F.getEmptyTree());
1010     }
1011
1012     /// add - Creates a new immutable set that contains all of the values
1013     ///  of the original set with the addition of the specified value.  If
1014     ///  the original set already included the value, then the original set is
1015     ///  returned and no memory is allocated.  The time and space complexity
1016     ///  of this operation is logarithmic in the size of the original set.
1017     ///  The memory allocated to represent the set is released when the
1018     ///  factory object that created the set is destroyed.
1019     LLVM_NODISCARD ImmutableSet add(ImmutableSet Old, value_type_ref V) {
1020       TreeTy *NewT = F.add(Old.Root, V);
1021       return ImmutableSet(Canonicalize ? F.getCanonicalTree(NewT) : NewT);
1022     }
1023
1024     /// remove - Creates a new immutable set that contains all of the values
1025     ///  of the original set with the exception of the specified value.  If
1026     ///  the original set did not contain the value, the original set is
1027     ///  returned and no memory is allocated.  The time and space complexity
1028     ///  of this operation is logarithmic in the size of the original set.
1029     ///  The memory allocated to represent the set is released when the
1030     ///  factory object that created the set is destroyed.
1031     LLVM_NODISCARD ImmutableSet remove(ImmutableSet Old, value_type_ref V) {
1032       TreeTy *NewT = F.remove(Old.Root, V);
1033       return ImmutableSet(Canonicalize ? F.getCanonicalTree(NewT) : NewT);
1034     }
1035
1036     BumpPtrAllocator& getAllocator() { return F.getAllocator(); }
1037
1038     typename TreeTy::Factory *getTreeFactory() const {
1039       return const_cast<typename TreeTy::Factory *>(&F);
1040     }
1041   };
1042
1043   friend class Factory;
1044
1045   /// Returns true if the set contains the specified value.
1046   bool contains(value_type_ref V) const {
1047     return Root ? Root->contains(V) : false;
1048   }
1049
1050   bool operator==(const ImmutableSet &RHS) const {
1051     return Root && RHS.Root ? Root->isEqual(*RHS.Root) : Root == RHS.Root;
1052   }
1053
1054   bool operator!=(const ImmutableSet &RHS) const {
1055     return Root && RHS.Root ? Root->isNotEqual(*RHS.Root) : Root != RHS.Root;
1056   }
1057
1058   TreeTy *getRoot() {
1059     if (Root) { Root->retain(); }
1060     return Root;
1061   }
1062
1063   TreeTy *getRootWithoutRetain() const {
1064     return Root;
1065   }
1066
1067   /// isEmpty - Return true if the set contains no elements.
1068   bool isEmpty() const { return !Root; }
1069
1070   /// isSingleton - Return true if the set contains exactly one element.
1071   ///   This method runs in constant time.
1072   bool isSingleton() const { return getHeight() == 1; }
1073
1074   template <typename Callback>
1075   void foreach(Callback& C) { if (Root) Root->foreach(C); }
1076
1077   template <typename Callback>
1078   void foreach() { if (Root) { Callback C; Root->foreach(C); } }
1079
1080   //===--------------------------------------------------===//
1081   // Iterators.
1082   //===--------------------------------------------------===//
1083
1084   using iterator = ImutAVLValueIterator<ImmutableSet>;
1085
1086   iterator begin() const { return iterator(Root); }
1087   iterator end() const { return iterator(); }
1088
1089   //===--------------------------------------------------===//
1090   // Utility methods.
1091   //===--------------------------------------------------===//
1092
1093   unsigned getHeight() const { return Root ? Root->getHeight() : 0; }
1094
1095   static void Profile(FoldingSetNodeID &ID, const ImmutableSet &S) {
1096     ID.AddPointer(S.Root);
1097   }
1098
1099   void Profile(FoldingSetNodeID &ID) const { return Profile(ID, *this); }
1100
1101   //===--------------------------------------------------===//
1102   // For testing.
1103   //===--------------------------------------------------===//
1104
1105   void validateTree() const { if (Root) Root->validateTree(); }
1106 };
1107
1108 // NOTE: This may some day replace the current ImmutableSet.
1109 template <typename ValT, typename ValInfo = ImutContainerInfo<ValT>>
1110 class ImmutableSetRef {
1111 public:
1112   using value_type = typename ValInfo::value_type;
1113   using value_type_ref = typename ValInfo::value_type_ref;
1114   using TreeTy = ImutAVLTree<ValInfo>;
1115   using FactoryTy = typename TreeTy::Factory;
1116
1117 private:
1118   TreeTy *Root;
1119   FactoryTy *Factory;
1120
1121 public:
1122   /// Constructs a set from a pointer to a tree root.  In general one
1123   /// should use a Factory object to create sets instead of directly
1124   /// invoking the constructor, but there are cases where make this
1125   /// constructor public is useful.
1126   explicit ImmutableSetRef(TreeTy* R, FactoryTy *F)
1127     : Root(R),
1128       Factory(F) {
1129     if (Root) { Root->retain(); }
1130   }
1131
1132   ImmutableSetRef(const ImmutableSetRef &X)
1133     : Root(X.Root),
1134       Factory(X.Factory) {
1135     if (Root) { Root->retain(); }
1136   }
1137
1138   ~ImmutableSetRef() {
1139     if (Root) { Root->release(); }
1140   }
1141
1142   ImmutableSetRef &operator=(const ImmutableSetRef &X) {
1143     if (Root != X.Root) {
1144       if (X.Root) { X.Root->retain(); }
1145       if (Root) { Root->release(); }
1146       Root = X.Root;
1147       Factory = X.Factory;
1148     }
1149     return *this;
1150   }
1151
1152   static ImmutableSetRef getEmptySet(FactoryTy *F) {
1153     return ImmutableSetRef(0, F);
1154   }
1155
1156   ImmutableSetRef add(value_type_ref V) {
1157     return ImmutableSetRef(Factory->add(Root, V), Factory);
1158   }
1159
1160   ImmutableSetRef remove(value_type_ref V) {
1161     return ImmutableSetRef(Factory->remove(Root, V), Factory);
1162   }
1163
1164   /// Returns true if the set contains the specified value.
1165   bool contains(value_type_ref V) const {
1166     return Root ? Root->contains(V) : false;
1167   }
1168
1169   ImmutableSet<ValT> asImmutableSet(bool canonicalize = true) const {
1170     return ImmutableSet<ValT>(canonicalize ?
1171                               Factory->getCanonicalTree(Root) : Root);
1172   }
1173
1174   TreeTy *getRootWithoutRetain() const {
1175     return Root;
1176   }
1177
1178   bool operator==(const ImmutableSetRef &RHS) const {
1179     return Root && RHS.Root ? Root->isEqual(*RHS.Root) : Root == RHS.Root;
1180   }
1181
1182   bool operator!=(const ImmutableSetRef &RHS) const {
1183     return Root && RHS.Root ? Root->isNotEqual(*RHS.Root) : Root != RHS.Root;
1184   }
1185
1186   /// isEmpty - Return true if the set contains no elements.
1187   bool isEmpty() const { return !Root; }
1188
1189   /// isSingleton - Return true if the set contains exactly one element.
1190   ///   This method runs in constant time.
1191   bool isSingleton() const { return getHeight() == 1; }
1192
1193   //===--------------------------------------------------===//
1194   // Iterators.
1195   //===--------------------------------------------------===//
1196
1197   using iterator = ImutAVLValueIterator<ImmutableSetRef>;
1198
1199   iterator begin() const { return iterator(Root); }
1200   iterator end() const { return iterator(); }
1201
1202   //===--------------------------------------------------===//
1203   // Utility methods.
1204   //===--------------------------------------------------===//
1205
1206   unsigned getHeight() const { return Root ? Root->getHeight() : 0; }
1207
1208   static void Profile(FoldingSetNodeID &ID, const ImmutableSetRef &S) {
1209     ID.AddPointer(S.Root);
1210   }
1211
1212   void Profile(FoldingSetNodeID &ID) const { return Profile(ID, *this); }
1213
1214   //===--------------------------------------------------===//
1215   // For testing.
1216   //===--------------------------------------------------===//
1217
1218   void validateTree() const { if (Root) Root->validateTree(); }
1219 };
1220
1221 } // end namespace llvm
1222
1223 #endif // LLVM_ADT_IMMUTABLESET_H