1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
#pragma once
#include "coding/byte_stream.hpp"
#include "coding/varint.hpp"
#include "base/buffer_vector.hpp"
#include "std/algorithm.hpp"
// Trie format:
// [1: header]
// [node] ... [node]
// Nodes are written in post-order (first child, last child, parent). Contents of nodes is writern
// reversed. The resulting file should be reverese before use! Then its contents will appear in
// pre-order alphabetically reversed (parent, last child, first child).
// Leaf node format:
// [value] ... [value]
// Internal node format:
// [1: header]: [2: min(valueCount, 3)] [6: min(childCount, 63)]
// [vu valueCount]: if valueCount in header == 3
// [vu childCount]: if childCount in header == 63
// [value] ... [value]
// [childInfo] ... [childInfo]
// Child info format:
// Every char of the edge is encoded as varint difference from the previous char. First char is
// encoded as varint difference from the base char, which is the last char of the current prefix.
//
// [1: header]: [1: isLeaf] [1: isShortEdge] [6: (edgeChar0 - baseChar) or min(edgeLen-1, 63)]
// [vu edgeLen-1]: if edgeLen-1 in header == 63
// [vi edgeChar0 - baseChar]
// [vi edgeChar1 - edgeChar0]
// ...
// [vi edgeCharN - edgeCharN-1]
// [child size]: if the child is not the last one when reading
namespace trie
{
template <typename TSink, typename TChildIter, typename TValueList>
void WriteNode(TSink & sink, TrieChar baseChar, TValueList const & valueList,
TChildIter const begChild, TChildIter const endChild, bool isRoot = false)
{
if (begChild == endChild && !isRoot)
{
// Leaf node.
valueList.Dump(sink);
return;
}
uint32_t const childCount = endChild - begChild;
uint32_t const valueCount = valueList.size();
uint8_t const header = static_cast<uint32_t>((min(valueCount, 3U) << 6) + min(childCount, 63U));
sink.Write(&header, 1);
if (valueCount >= 3)
WriteVarUint(sink, valueCount);
if (childCount >= 63)
WriteVarUint(sink, childCount);
valueList.Dump(sink);
for (TChildIter it = begChild; it != endChild; /*++it*/)
{
uint8_t header = (it->IsLeaf() ? 128 : 0);
TrieChar const * const edge = it->GetEdge();
uint32_t const edgeSize = it->GetEdgeSize();
CHECK_NOT_EQUAL(edgeSize, 0, ());
CHECK_LESS(edgeSize, 100000, ());
uint32_t const diff0 = bits::ZigZagEncode(int32_t(edge[0] - baseChar));
if (edgeSize == 1 && (diff0 & ~63U) == 0)
{
header |= 64;
header |= diff0;
WriteToSink(sink, header);
}
else
{
if (edgeSize - 1 < 63)
{
header |= edgeSize - 1;
WriteToSink(sink, header);
}
else
{
header |= 63;
WriteToSink(sink, header);
WriteVarUint(sink, edgeSize - 1);
}
for (uint32_t i = 0; i < edgeSize; ++i)
{
WriteVarInt(sink, int32_t(edge[i] - baseChar));
baseChar = edge[i];
}
}
baseChar = edge[0];
uint32_t const childSize = it->Size();
if (++it != endChild)
WriteVarUint(sink, childSize);
}
}
struct ChildInfo
{
bool m_isLeaf;
uint32_t m_size;
buffer_vector<TrieChar, 8> m_edge;
ChildInfo(bool isLeaf, uint32_t size, TrieChar c) : m_isLeaf(isLeaf), m_size(size), m_edge(1, c)
{
}
uint32_t Size() const { return m_size; }
bool IsLeaf() const { return m_isLeaf; }
TrieChar const * GetEdge() const { return m_edge.data(); }
uint32_t GetEdgeSize() const { return m_edge.size(); }
};
template <typename TValueList>
struct NodeInfo
{
uint64_t m_begPos;
TrieChar m_char;
vector<ChildInfo> m_children;
TValueList m_valueList;
NodeInfo() : m_begPos(0), m_char(0) {}
NodeInfo(uint64_t pos, TrieChar trieChar) : m_begPos(pos), m_char(trieChar) {}
};
template <typename TSink, typename TValueList>
void WriteNodeReverse(TSink & sink, TrieChar baseChar, NodeInfo<TValueList> const & node,
bool isRoot = false)
{
using TOutStorage = buffer_vector<uint8_t, 64>;
TOutStorage out;
PushBackByteSink<TOutStorage> outSink(out);
WriteNode(outSink, baseChar, node.m_valueList, node.m_children.rbegin(), node.m_children.rend(),
isRoot);
reverse(out.begin(), out.end());
sink.Write(out.data(), out.size());
}
template <typename TSink, class TNodes>
void PopNodes(TSink & sink, TNodes & nodes, int nodesToPop)
{
using TNodeInfo = typename TNodes::value_type;
ASSERT_GREATER(nodes.size(), nodesToPop, ());
for (; nodesToPop > 0; --nodesToPop)
{
TNodeInfo & node = nodes.back();
TNodeInfo & prevNode = nodes[nodes.size() - 2];
if (node.m_valueList.empty() && node.m_children.size() <= 1)
{
ASSERT_EQUAL(node.m_children.size(), 1, ());
ChildInfo & child = node.m_children[0];
prevNode.m_children.push_back(ChildInfo(child.m_isLeaf, child.m_size, node.m_char));
prevNode.m_children.back().m_edge.append(child.m_edge.begin(), child.m_edge.end());
}
else
{
WriteNodeReverse(sink, node.m_char, node);
prevNode.m_children.push_back(ChildInfo(node.m_children.empty(),
static_cast<uint32_t>(sink.Pos() - node.m_begPos),
node.m_char));
}
nodes.pop_back();
}
}
template <typename TSink, typename TIter, typename TValueList>
void Build(TSink & sink, TIter const beg, TIter const end)
{
using TTrieString = buffer_vector<TrieChar, 32>;
using TNodeInfo = NodeInfo<TValueList>;
buffer_vector<TNodeInfo, 32> nodes;
nodes.push_back(TNodeInfo(sink.Pos(), DEFAULT_CHAR));
TTrieString prevKey;
using TElement = typename TIter::value_type;
TElement prevE;
for (TIter it = beg; it != end; ++it)
{
TElement e = *it;
if (it != beg && e == prevE)
continue;
TrieChar const * const pKeyData = e.GetKeyData();
TTrieString key(pKeyData, pKeyData + e.GetKeySize());
CHECK(!(key < prevKey), (key, prevKey));
size_t nCommon = 0;
while (nCommon < min(key.size(), prevKey.size()) && prevKey[nCommon] == key[nCommon])
++nCommon;
PopNodes(sink, nodes, nodes.size() - nCommon - 1); // Root is also a common node.
uint64_t const pos = sink.Pos();
for (size_t i = nCommon; i < key.size(); ++i)
nodes.push_back(TNodeInfo(pos, key[i]));
nodes.back().m_valueList.Append(e.GetValue());
prevKey.swap(key);
prevE.Swap(e);
}
// Pop all the nodes from the stack.
PopNodes(sink, nodes, nodes.size() - 1);
// Write the root.
WriteNodeReverse(sink, DEFAULT_CHAR /* baseChar */, nodes.back(), true /* isRoot */);
}
} // namespace trie
|
