1 //===- llvm/ADT/IndexedMap.h - An index map implementation ------*- 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 implements an indexed map. The index map template takes two
11 // types. The first is the mapped type and the second is a functor
12 // that maps its argument to a size_t. On instantiation a "null" value
13 // can be provided to be used as a "does not exist" indicator in the
14 // map. A member function grow() is provided that given the value of
15 // the maximally indexed key (the argument of the functor) makes sure
16 // the map has enough space for it.
17 //
18 //===----------------------------------------------------------------------===//
19 
20 #ifndef LLVM_ADT_INDEXEDMAP_H
21 #define LLVM_ADT_INDEXEDMAP_H
22 
23 #include "llvm/ADT/STLExtras.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include <cassert>
26 #include <functional>
27 
28 namespace llvm {
29 
30 template <typename T, typename ToIndexT = llvm::identity<unsigned> >
31   class IndexedMap {
32     typedef typename ToIndexT::argument_type IndexT;
33     // Prefer SmallVector with zero inline storage over std::vector. IndexedMaps
34     // can grow very large and SmallVector grows more efficiently as long as T
35     // is trivially copyable.
36     typedef SmallVector<T, 0> StorageT;
37     StorageT storage_;
38     T nullVal_;
39     ToIndexT toIndex_;
40 
41   public:
IndexedMap()42     IndexedMap() : nullVal_(T()) { }
43 
IndexedMap(const T & val)44     explicit IndexedMap(const T& val) : nullVal_(val) { }
45 
46     typename StorageT::reference operator[](IndexT n) {
47       assert(toIndex_(n) < storage_.size() && "index out of bounds!");
48       return storage_[toIndex_(n)];
49     }
50 
51     typename StorageT::const_reference operator[](IndexT n) const {
52       assert(toIndex_(n) < storage_.size() && "index out of bounds!");
53       return storage_[toIndex_(n)];
54     }
55 
reserve(typename StorageT::size_type s)56     void reserve(typename StorageT::size_type s) {
57       storage_.reserve(s);
58     }
59 
resize(typename StorageT::size_type s)60     void resize(typename StorageT::size_type s) {
61       storage_.resize(s, nullVal_);
62     }
63 
clear()64     void clear() {
65       storage_.clear();
66     }
67 
grow(IndexT n)68     void grow(IndexT n) {
69       unsigned NewSize = toIndex_(n) + 1;
70       if (NewSize > storage_.size())
71         resize(NewSize);
72     }
73 
inBounds(IndexT n)74     bool inBounds(IndexT n) const {
75       return toIndex_(n) < storage_.size();
76     }
77 
size()78     typename StorageT::size_type size() const {
79       return storage_.size();
80     }
81   };
82 
83 } // End llvm namespace
84 
85 #endif
86