サロゲートペアを考慮してSubstringできるやつ | Codetter（こーどったー）

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
using System;
using System.Collections.Generic;
using System.Text;
namespace Liberfy
{
    public sealed unsafe class TwStringInfo : IDisposable
    {
        #region fields
        private int* surrogateIndices;
        private int surrogateIndicesLength;
        #endregion
        #region properties
        public string String { get; private set; }
        public int Length { get; private set; }
        #endregion
        public TwStringInfo(string text)
        {
            if (text == null) return;
            var surrogateIndicesList = new LinkedList<int>();
            String = text.Normalize(NormalizationForm.FormC);
            char c;
            int Length = String.Length;
            int surrogateIndex;
            for (surrogateIndex = 0; surrogateIndex < Length; surrogateIndex++)
            {
                if ('\uD800' <= (c = String[surrogateIndex]) && c <= '\uDBFF')
                {
                    surrogateIndicesList.AddLast(surrogateIndex);
                    surrogateIndex++;
                }
            }
            surrogateIndicesLength = surrogateIndicesList.Count;
            if (surrogateIndicesLength > 0)
            {
                int* indices = stackalloc int[surrogateIndicesLength];
                LinkedListNode<int> node = surrogateIndicesList.First;
                for (int i = 0; i < surrogateIndicesLength; i++)
                {
                    indices[i] = node.Value;
                    node = node.Next;
                }
                surrogateIndices = indices;
                indices = null;
                surrogateIndicesList.Clear();
            }
            surrogateIndicesList = null;
        }
        public string Substring(int startIndex)
        {
            int substringStartIndex = startIndex;
            for (int i = 0; i < surrogateIndicesLength; i++)
            {
                if (surrogateIndices[i] < startIndex)
                {
                    substringStartIndex++;
                }
                else
                {
                    break;
                }
            }
            return String.Substring(substringStartIndex);
        }
        public string Substring(int startIndex, int length)
        {
            int i = 0;
            int substringStartIndex = startIndex;
            int substringLength = length;
            int totalLength = startIndex + length;
            for (; i < surrogateIndicesLength; i++)
            {
                if (surrogateIndices[i] < startIndex)
                {
                    substringStartIndex++;
                }
                else
                {
                    break;
                }
            }
            for (; i < surrogateIndicesLength; i++)
            {
                if (surrogateIndices[i] < totalLength)
                {
                    substringLength++;
                }
                else
                {
                    break;
                }
            }
            return String.Substring(substringStartIndex, substringLength);
        }
        #region IDisposable Support
        private bool disposedValue = false;
        private void Dispose(bool disposing)
        {
            if (!disposedValue)
            {
                if (disposing)
                {
                    Length = 0;
                    String = null;
                }
                else
                {
                    surrogateIndices = null;
                    surrogateIndicesLength = 0;
                }
                disposedValue = true;
            }
        }
        ~TwStringInfo()
        {
            Dispose(false);
        }
        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }
        #endregion
    }
}
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX