TinyPtrVector.h revision 840635741f132a9a10f052cbf3b21e14bc74835a 
1//===- llvm/ADT/TinyPtrVector.h - 'Normally tiny' vectors -------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file defines the Type class.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_ADT_TINYPTRVECTOR_H
15#define LLVM_ADT_TINYPTRVECTOR_H
16
17#include "llvm/ADT/SmallVector.h"
18#include "llvm/ADT/PointerUnion.h"
19
20namespace llvm {
21
22/// TinyPtrVector - This class is specialized for cases where there are
23/// normally 0 or 1 element in a vector, but is general enough to go beyond that
24/// when required.
25///
26/// NOTE: This container doesn't allow you to store a null pointer into it.
27///
28template <typename EltTy>
29class TinyPtrVector {
30public:
31  typedef llvm::SmallVector<EltTy, 4> VecTy;
32  llvm::PointerUnion<EltTy, VecTy*> Val;
33
34  TinyPtrVector() {}
35  TinyPtrVector(const TinyPtrVector &RHS) : Val(RHS.Val) {
36    if (VecTy *V = Val.template dyn_cast<VecTy*>())
37      Val = new VecTy(*V);
38  }
39  ~TinyPtrVector() {
40    if (VecTy *V = Val.template dyn_cast<VecTy*>())
41      delete V;
42  }
43
44  /// empty() - This vector can be empty if it contains no element, or if it
45  /// contains a pointer to an empty vector.
46  bool empty() const {
47    if (Val.isNull()) return true;
48    if (VecTy *Vec = Val.template dyn_cast<VecTy*>())
49      return Vec->empty();
50    return false;
51  }
52
53  unsigned size() const {
54    if (empty())
55      return 0;
56    if (Val. template is<EltTy>())
57      return 1;
58    return Val. template get<VecTy*>()->size();
59  }
60
61  EltTy operator[](unsigned i) const {
62    assert(!Val.isNull() && "can't index into an empty vector");
63    if (EltTy V = Val.template dyn_cast<EltTy>()) {
64      assert(i == 0 && "tinyvector index out of range");
65      return V;
66    }
67
68    assert(i < Val. template get<VecTy*>()->size() &&
69           "tinyvector index out of range");
70    return (*Val. template get<VecTy*>())[i];
71  }
72
73  EltTy front() const {
74    assert(!empty() && "vector empty");
75    if (EltTy V = Val.template dyn_cast<EltTy>())
76      return V;
77    return Val.template get<VecTy*>()->front();
78  }
79
80  void push_back(EltTy NewVal) {
81    assert(NewVal != 0 && "Can't add a null value");
82
83    // If we have nothing, add something.
84    if (Val.isNull()) {
85      Val = NewVal;
86      return;
87    }
88
89    // If we have a single value, convert to a vector.
90    if (EltTy V = Val.template  dyn_cast<EltTy>()) {
91      Val = new VecTy();
92      Val.template get<VecTy*>()->push_back(V);
93    }
94
95    // Add the new value, we know we have a vector.
96    Val.template get<VecTy*>()->push_back(NewVal);
97  }
98
99  void clear() {
100    // If we have a single value, convert to empty.
101    if (Val.template is<EltTy>()) {
102      Val = (EltTy)0;
103    } else if (VecTy *Vec = Val.template dyn_cast<VecTy*>()) {
104      // If we have a vector form, just clear it.
105      Vec->clear();
106    }
107    // Otherwise, we're already empty.
108  }
109
110private:
111  void operator=(const TinyPtrVector&); // NOT IMPLEMENTED YET.
112};
113} // end namespace llvm
114
115#endif
116