1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #ifndef TOOLS_GN_UNIQUE_VECTOR_H_
6 #define TOOLS_GN_UNIQUE_VECTOR_H_
10 #include "base/containers/hash_tables.h"
14 // This lass allows us to insert things by reference into a hash table which
15 // avoids copies. The hash function of a UniquifyRef is that of the object it
18 // There are two ways it can store data: (1) by (vector*, index) which is used
19 // to refer to the array in UniqueVector and make it work even when the
20 // underlying vector is reallocated; (2) by T* which is used to do lookups
21 // into the hash table of things that aren't in a vector yet.
23 // It also caches the hash value which allows us to query and then insert
24 // without recomputing the hash.
31 index_(static_cast<size_t>(-1)),
35 // Initialize with a pointer to a value.
36 UniquifyRef(const T* v)
39 index_(static_cast<size_t>(-1)) {
43 // Initialize with an array + index.
44 UniquifyRef(const std::vector<T>* v, size_t i)
51 // Initialize with an array + index and a known hash value to prevent
53 UniquifyRef(const std::vector<T>* v, size_t i, size_t hash_value)
57 hash_val_(hash_value) {
60 const T& value() const { return value_ ? *value_ : (*vect_)[index_]; }
61 size_t hash_val() const { return hash_val_; }
62 size_t index() const { return index_; }
65 void FillHashValue() {
66 BASE_HASH_NAMESPACE::hash<T> h;
67 hash_val_ = h(value());
70 // When non-null, points to the object.
73 // When value is null these are used.
74 const std::vector<T>* vect_;
80 template<typename T> inline bool operator==(const UniquifyRef<T>& a,
81 const UniquifyRef<T>& b) {
82 return a.value() == b.value();
85 template<typename T> inline bool operator<(const UniquifyRef<T>& a,
86 const UniquifyRef<T>& b) {
87 return a.value() < b.value();
90 } // namespace internal
92 namespace BASE_HASH_NAMESPACE {
94 template<typename T> struct hash< internal::UniquifyRef<T> > {
95 std::size_t operator()(const internal::UniquifyRef<T>& v) const {
100 } // namespace BASE_HASH_NAMESPACE
102 // An ordered set optimized for GN's usage. Such sets are used to store lists
103 // of configs and libraries, and are appended to but not randomly inserted
108 typedef std::vector<T> Vector;
109 typedef typename Vector::iterator iterator;
110 typedef typename Vector::const_iterator const_iterator;
112 const Vector& vector() const { return vector_; }
113 size_t size() const { return vector_.size(); }
114 bool empty() const { return vector_.empty(); }
115 void clear() { vector_.clear(); set_.clear(); }
116 void reserve(size_t s) { vector_.reserve(s); }
118 const T& operator[](size_t index) const { return vector_[index]; }
120 const_iterator begin() const { return vector_.begin(); }
121 iterator begin() { return vector_.begin(); }
122 const_iterator end() const { return vector_.end(); }
123 iterator end() { return vector_.end(); }
125 // Returns true if the item was appended, false if it already existed (and
126 // thus the vector was not modified).
127 bool push_back(const T& t) {
129 if (set_.find(ref) != set_.end())
130 return false; // Already have this one.
132 vector_.push_back(t);
133 set_.insert(Ref(&vector_, vector_.size() - 1, ref.hash_val()));
137 // Like push_back but swaps in the type to avoid a copy.
138 bool PushBackViaSwap(T* t) {
142 if (set_.find(ref) != set_.end())
143 return false; // Already have this one.
145 size_t new_index = vector_.size();
146 vector_.resize(new_index + 1);
147 swap(vector_[new_index], *t);
148 set_.insert(Ref(&vector_, vector_.size() - 1, ref.hash_val()));
152 // Appends a range of items from an iterator.
153 template<typename iter> void Append(const iter& begin, const iter& end) {
154 for (iter i = begin; i != end; ++i)
158 // Returns the index of the item matching the given value in the list, or
159 // (size_t)(-1) if it's not found.
160 size_t IndexOf(const T& t) const {
162 typename HashSet::const_iterator found = set_.find(ref);
163 if (found == set_.end())
164 return static_cast<size_t>(-1);
165 return found->index();
169 typedef internal::UniquifyRef<T> Ref;
170 typedef base::hash_set<Ref> HashSet;
176 #endif // TOOLS_GN_UNIQUE_VECTOR_H_