1 /*
2  * Copyright (C) 2014 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef LATINIME_INT_ARRAY_VIEW_H
18 #define LATINIME_INT_ARRAY_VIEW_H
19 
20 #include <algorithm>
21 #include <array>
22 #include <cstdint>
23 #include <cstring>
24 #include <vector>
25 
26 #include "defines.h"
27 
28 namespace latinime {
29 
30 /**
31  * Helper class used to provide a read-only view of a given range of integer array. This class
32  * does not take ownership of the underlying integer array but is designed to be a lightweight
33  * object that obeys value semantics.
34  *
35  * Example:
36  * <code>
37  * bool constinsX(IntArrayView view) {
38  *     for (size_t i = 0; i < view.size(); ++i) {
39  *         if (view[i] == 'X') {
40  *             return true;
41  *         }
42  *     }
43  *     return false;
44  * }
45  *
46  * const int codePointArray[] = { 'A', 'B', 'X', 'Z' };
47  * auto view = IntArrayView(codePointArray, NELEMS(codePointArray));
48  * const bool hasX = constinsX(view);
49  * </code>
50  */
51 class IntArrayView {
52  public:
IntArrayView()53     IntArrayView() : mPtr(nullptr), mSize(0) {}
54 
IntArrayView(const int * const ptr,const size_t size)55     IntArrayView(const int *const ptr, const size_t size)
56             : mPtr(ptr), mSize(size) {}
57 
IntArrayView(const std::vector<int> & vector)58     explicit IntArrayView(const std::vector<int> &vector)
59             : mPtr(vector.data()), mSize(vector.size()) {}
60 
61     template <size_t N>
fromArray(const std::array<int,N> & array)62     AK_FORCE_INLINE static IntArrayView fromArray(const std::array<int, N> &array) {
63         return IntArrayView(array.data(), array.size());
64     }
65 
66     // Returns a view that points one int object.
singleElementView(const int * const ptr)67     AK_FORCE_INLINE static IntArrayView singleElementView(const int *const ptr) {
68         return IntArrayView(ptr, 1);
69     }
70 
71     AK_FORCE_INLINE int operator[](const size_t index) const {
72         ASSERT(index < mSize);
73         return mPtr[index];
74     }
75 
empty()76     AK_FORCE_INLINE bool empty() const {
77         return size() == 0;
78     }
79 
size()80     AK_FORCE_INLINE size_t size() const {
81         return mSize;
82     }
83 
data()84     AK_FORCE_INLINE const int *data() const {
85         return mPtr;
86     }
87 
begin()88     AK_FORCE_INLINE const int *begin() const {
89         return mPtr;
90     }
91 
end()92     AK_FORCE_INLINE const int *end() const {
93         return mPtr + mSize;
94     }
95 
contains(const int value)96     AK_FORCE_INLINE bool contains(const int value) const {
97         return std::find(begin(), end(), value) != end();
98     }
99 
100     // Returns the view whose size is smaller than or equal to the given count.
limit(const size_t maxSize)101     AK_FORCE_INLINE const IntArrayView limit(const size_t maxSize) const {
102         return IntArrayView(mPtr, std::min(maxSize, mSize));
103     }
104 
skip(const size_t n)105     AK_FORCE_INLINE const IntArrayView skip(const size_t n) const {
106         if (mSize <= n) {
107             return IntArrayView();
108         }
109         return IntArrayView(mPtr + n, mSize - n);
110     }
111 
112     template <size_t N>
copyToArray(std::array<int,N> * const buffer,const size_t offset)113     void copyToArray(std::array<int, N> *const buffer, const size_t offset) const {
114         ASSERT(mSize + offset <= N);
115         memmove(buffer->data() + offset, mPtr, sizeof(int) * mSize);
116     }
117 
firstOrDefault(const int defaultValue)118     AK_FORCE_INLINE int firstOrDefault(const int defaultValue) const {
119         if (empty()) {
120             return defaultValue;
121         }
122         return mPtr[0];
123     }
124 
lastOrDefault(const int defaultValue)125     AK_FORCE_INLINE int lastOrDefault(const int defaultValue) const {
126         if (empty()) {
127             return defaultValue;
128         }
129         return mPtr[mSize - 1];
130     }
131 
toVector()132     AK_FORCE_INLINE std::vector<int> toVector() const {
133         return std::vector<int>(begin(), end());
134     }
135 
136     std::vector<IntArrayView> split(const int separator, const int limit = S_INT_MAX) const {
137         if (limit <= 0) {
138             return std::vector<IntArrayView>();
139         }
140         std::vector<IntArrayView> result;
141         if (limit == 1) {
142             result.emplace_back(mPtr, mSize);
143             return result;
144         }
145         size_t startIndex = 0;
146         for (size_t i = 0; i < mSize; ++i) {
147             if (mPtr[i] == separator) {
148                 result.emplace_back(mPtr + startIndex, i - startIndex);
149                 startIndex = i + 1;
150                 if (result.size() >= static_cast<size_t>(limit - 1)) {
151                     break;
152                 }
153             }
154         }
155         result.emplace_back(mPtr + startIndex, mSize - startIndex);
156         return result;
157     }
158 
159  private:
160     DISALLOW_ASSIGNMENT_OPERATOR(IntArrayView);
161 
162     const int *const mPtr;
163     const size_t mSize;
164 };
165 
166 using WordIdArrayView = IntArrayView;
167 using PtNodePosArrayView = IntArrayView;
168 using CodePointArrayView = IntArrayView;
169 template <size_t size>
170 using WordIdArray = std::array<int, size>;
171 
172 } // namespace latinime
173 #endif // LATINIME_MEMORY_VIEW_H
174