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Issue 29333474: Issue 4125 - [emscripten] Convert filter classes to C++ (Closed)
Patch Set: Addressed comments from Patch Set 26 Created March 13, 2017, 5:36 p.m.
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1 #pragma once
2
3 #include <cstddef>
4 #include <cmath>
5 #include <initializer_list>
6 #include <memory>
7
8 #include "String.h"
9 #include "debug.h"
10
11 template<typename T>
12 class StringMap;
13
14 namespace StringMap_internal
15 {
16 template<typename Entry>
17 struct HashContainerIterator
18 {
19 typedef Entry entry_type;
20 typedef HashContainerIterator<Entry> iterator;
21
22 const entry_type* mPos;
23 const entry_type* mEnd;
24
25 explicit HashContainerIterator(const entry_type* start, const entry_type* en d)
26 : mPos(start), mEnd(end)
27 {
28 if (mPos != mEnd && mPos->first.is_invalid())
29 ++(*this);
30 }
31
32 const entry_type& operator*() const
33 {
34 return *mPos;
35 }
36
37 const entry_type* operator->() const
38 {
39 return mPos;
40 }
41
42 iterator& operator++()
43 {
44 do {
45 ++mPos;
46 } while(mPos != mEnd && mPos->first.is_invalid());
47 return *this;
48 }
49
50 bool operator==(const iterator& it) const
51 {
52 return mPos == it.mPos;
53 }
54
55 bool operator!=(const iterator& it) const
56 {
57 return mPos != it.mPos;
58 }
59 };
60
61 template<typename Entry>
62 struct HashContainerReference
63 {
64 typedef Entry entry_type;
65
66 entry_type* mEntry;
67
68 explicit HashContainerReference(entry_type* entry)
69 : mEntry(entry)
70 {
71 }
72
73 const entry_type* operator->() const
74 {
75 return mEntry;
76 }
77
78 operator bool() const
79 {
80 return !mEntry->first.is_invalid();
81 }
82 };
83
84 template<typename Entry>
85 class HashContainer
86 {
87 public:
88 typedef Entry entry_type;
89 typedef size_t size_type;
90 typedef HashContainerIterator<Entry> const_iterator;
91 typedef HashContainerReference<const Entry> const_reference;
92
93 private:
94 explicit HashContainer(const HashContainer& other);
95 void operator=(const HashContainer& other);
96
97 protected:
98 static constexpr size_type MIN_BUCKETS = 1;
99 static constexpr double LOAD_FACTOR = 0.8;
100 std::unique_ptr<entry_type[]> mBuckets;
101 size_type mBucketCount;
102 size_type mEntryCount;
103
104 #if defined(DEBUG)
105 size_type mInsertCounter;
106 #endif
107
108 explicit HashContainer(size_type expectedEntries = 0)
109 : mEntryCount(0)
110 {
111 expectedEntries = ceil(expectedEntries / LOAD_FACTOR);
112 mBucketCount = MIN_BUCKETS;
113 while (mBucketCount < expectedEntries)
114 mBucketCount <<= 1;
115
116 mBuckets.reset(new entry_type[mBucketCount]);
117 // Working around https://github.com/waywardmonkeys/emscripten-trace-colle ctor/issues/2 here
118 annotate_address(reinterpret_cast<size_type*>(mBuckets.get()) - 1, "Hash t able buffer");
119 }
120
121 static size_type hash(const String& str)
122 {
123 // FNV-1a hash function
124 size_type result = 2166136261;
125 for (String::size_type i = 0; i < str.length(); i++)
126 result = (result ^ str[i]) * 16777619;
127 return result;
128 }
129
130 entry_type* find_bucket(const String& key) const
131 {
132 size_type h = hash(key);
133
134 // This does quadratic probing, effectively the following formula is used:
135 // pos = (hash + 1/2 i + 1/2 i ^ 2) mod bucketCount
136 for (size_type i = 0; ; ++i)
137 {
138 // mBucketCount is 2^n so (h & mBucketCount - 1) is equivalent to
139 // h % mBucketCount but significantly faster.
140 entry_type* entry = &mBuckets[h & (mBucketCount - 1)];
141 if (entry->first.is_invalid() || entry->first.equals(key))
142 return entry;
143 h += i;
144 }
145 }
146
147 void resize(size_type bucketCount)
148 {
149 std::unique_ptr<entry_type[]> oldBuckets(std::move(mBuckets));
150 size_type oldCount = mBucketCount;
151
152 mEntryCount = 0;
153 mBucketCount = bucketCount;
154 mBuckets.reset(new entry_type[mBucketCount]);
155 // Working around https://github.com/waywardmonkeys/emscripten-trace-colle ctor/issues/2 here
156 annotate_address(reinterpret_cast<size_type*>(mBuckets.get()) - 1, "Hash t able buffer");
157
158 // Copy old entries into the new buffer
159 for (size_type i = 0; i < oldCount; i++)
160 {
161 entry_type& entry = oldBuckets[i];
162 if (!entry.first.is_invalid() && !entry.first.is_deleted())
163 {
164 *find_bucket(entry.first) = entry;
165 mEntryCount++;
166 }
167 }
168 }
169
170 entry_type* assign(entry_type* existing, const entry_type& entry)
171 {
172 if (existing->first.is_invalid())
173 {
174 if (mEntryCount + 1 >= mBucketCount * LOAD_FACTOR)
175 {
176 resize(mBucketCount << 1);
177 existing = find_bucket(entry.first);
178 }
179 mEntryCount++;
180 #if defined(DEBUG)
181 mInsertCounter++;
182 #endif
183 }
184 *existing = entry;
185 return existing;
186 }
187
188 public:
189 void insert(const entry_type& entry)
190 {
191 assign(find_bucket(entry.first), entry);
192 }
193
194 bool erase(const String& key)
195 {
196 entry_type* entry = find_bucket(key);
197 if (entry->first.is_invalid())
198 return false;
199
200 entry->first.erase();
201 return true;
202 }
203
204 const_reference find(const String& key) const
205 {
206 return const_reference(find_bucket(key));
207 }
208
209 const_iterator begin() const
210 {
211 return const_iterator(&mBuckets[0], &mBuckets[mBucketCount]);
212 }
213
214 const_iterator end() const
215 {
216 return const_iterator(&mBuckets[mBucketCount], &mBuckets[mBucketCount]);
217 }
218 };
219
220 struct StringSetEntry
221 {
222 StringSetEntry() {}
223 StringSetEntry(const String& key)
224 : first(key)
225 {
226 }
227
228 DependentString first;
229 };
230
231 template<typename T>
232 struct StringMapEntry
233 {
234 StringMapEntry() {}
235 StringMapEntry(const String& key)
236 : first(key), second()
237 {
238 }
239 StringMapEntry(const String& key, T value)
240 : first(key), second(value)
241 {
242 }
243
244 DependentString first;
245 T second;
246 };
247
248 template<typename T>
249 struct StringMapEntryReference : public HashContainerReference<StringMapEntry< T>>
250 {
251 typedef HashContainerReference<StringMapEntry<T>> super;
252 typedef typename super::entry_type entry_type;
253 typedef StringMap<T> map_type;
254
255 map_type* mMap;
256
257 #if defined(DEBUG)
258 typename map_type::size_type mInsertCounter;
259 typename map_type::size_type mHash;
260 #endif
261
262 StringMapEntryReference(map_type* map, const String& key, entry_type* entry)
263 : super(entry), mMap(map)
264 {
265 #if defined(DEBUG)
266 mInsertCounter = mMap->mInsertCounter;
267 mHash = mMap->hash(key);
268 #endif
269 }
270
271 void assign(const String& key, const T& value)
272 {
273 #if defined(DEBUG)
274 assert(mInsertCounter == mMap->mInsertCounter,
275 u"There should be no insert operations performed between map.find() an d assign()"_str);
276 assert(mHash == mMap->hash(key),
277 u"The keys used in map.find() and assign() should be identical"_str);
278 #endif
279
280 mMap->assign(this->mEntry, entry_type(key, value));
281 }
282 };
283 }
284
285 class StringSet
286 : public StringMap_internal::HashContainer<StringMap_internal::StringSetEntry>
287 {
288 };
289
290 template<typename T>
291 class StringMap
292 : public StringMap_internal::HashContainer<StringMap_internal::StringMapEntry< T>>
293 {
294 public:
295 typedef StringMap_internal::HashContainer<StringMap_internal::StringMapEntry<T >> super;
296 typedef typename super::size_type size_type;
297 typedef typename super::entry_type entry_type;
298 typedef typename super::const_reference const_reference;
299 typedef StringMap_internal::StringMapEntryReference<T> reference;
300 friend class StringMap_internal::StringMapEntryReference<T>;
301
302 explicit StringMap(size_type expectedEntries = 0)
303 : super(expectedEntries)
304 {
305 }
306
307 StringMap(std::initializer_list<entry_type> list)
308 : super(list.size())
309 {
310 for (auto it = list.begin(); it != list.end(); ++it)
311 super::insert(*it);
312 }
313
314 ~StringMap()
315 {
316 }
317
318 T& operator[](const String& key)
319 {
320 entry_type* entry = super::find_bucket(key);
321 if (entry->first.is_invalid())
322 entry = super::assign(entry, key);
323 return entry->second;
324 }
325
326 const_reference find(const String& key) const
327 {
328 return super::find(key);
329 }
330
331 reference find(const String& key)
332 {
333 return reference(this, key, super::find_bucket(key));
334 }
335 };
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