1 | /*!
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2 | @file Classes/System/Text/UTF8Encoding.ab
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3 | @brief UTF8Encodingクラスとそれに関係するクラスなどの宣言・定義
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4 | */
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5 |
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6 | Namespace System
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7 | Namespace Text
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8 |
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9 | Namespace Detail
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10 |
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11 | Class UTF8Encoder
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12 | Inherits Encoder
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13 | Protected
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14 | Override Sub EncodeImpl(src As *WCHAR, size As SIZE_T, s As IO.Stream, last As Boolean)
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15 | Dim i As Long
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16 | For i = 0 To ELM(size)
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17 | If buffer <> 0 Then
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18 | If _System_IsLowSurrogate(src[i]) Then
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19 | 'UTF-16列からUnicodeコードポイントを復元
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20 | Dim c = (((buffer And &h3FF) As DWord << 10) Or (src[i] And &h3FF)) + &h10000
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21 | '4バイト変換
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22 | s.WriteByte(((c >> 18) Or &hf0) As Byte)
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23 | s.WriteByte(((c >> 12) And &h3F Or &h80) As Byte)
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24 | s.WriteByte(((c >> 6) And &h3F Or &h80) As Byte)
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25 | s.WriteByte((c And &h3F Or &h80) As Byte)
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26 | Else
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27 | writeReplacementChar(s)
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28 | End If
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29 | buffer = 0
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30 | ElseIf src[i] < &h80 Then
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31 | '1バイト変換
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32 | s.WriteByte(src[i] As Byte)
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33 | ElseIf src[i] < &h800 Then
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34 | '2バイト変換
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35 | s.WriteByte(((src[i] >> 6) Or &hC0) As Byte)
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36 | s.WriteByte((src[i] And &h3F Or &h80) As Byte)
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37 | ElseIf _System_IsHighSurrogate(src[i]) Then
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38 | 'バッファに貯め込む
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39 | buffer = src[i]
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40 | ElseIf _System_IsLowSurrogate(src[i]) Then
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41 | writeReplacementChar(s)
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42 | Else
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43 | '3バイト変換
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44 | s.WriteByte(((src[i] >> 12) Or &hE0) As Byte)
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45 | s.WriteByte(((src[i] >> 6) And &h3F Or &h80) As Byte)
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46 | s.WriteByte((src[i] And &h3F Or &h80) As Byte)
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47 | End If
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48 | Next
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49 | End Sub
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50 |
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51 | Private
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52 | ' U+FFFD Replacement CharacterのUTF-8表現、EF BF BDを書き込む。
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53 | Sub writeReplacementChar(s As IO.Stream)
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54 | Dim rc[2] = [&hef, &hbf, &hbd] As Byte
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55 | s.Write(rc, 0, Len(rc))
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56 | End Sub
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57 |
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58 | buffer As WCHAR
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59 | End Class
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60 |
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61 | Class UTF8Decoder
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62 | Inherits Decoder
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63 | Protected
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64 | Override Function DecodeImpl(dst As Collections.Generic.List<WCHAR>, s As IO.Stream) As Boolean
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65 | Dim i As Long
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66 | For i = 0 To DefalultDecodingBufferSize - 1 'ELM
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67 | Dim b = s.ReadByte()
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68 | If b = -1 Then
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69 | DecodeImpl = False
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70 | Exit Function
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71 | ElseIf state = 0 Then
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72 | If b <= &h80 Then
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73 | '1バイト変換
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74 | dst.Add(b As WCHAR)
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75 | ElseIf b < &hC0 Then
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76 | '先頭バイトがなく、いきなりマルチバイトの2バイト目以降
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77 | dst.Add(&hFFFD As WCHAR)
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78 | ElseIf b < &hD0 Then
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79 | '2バイト文字の始まり
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80 | last = 2
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81 | buffer = b And &h3F
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82 | state++
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83 | ElseIf b < &hF0 Then
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84 | '3バイト文字の始まり
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85 | last = 3
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86 | buffer = b And &h1F
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87 | state++
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88 | ElseIf b < &hF8 Then
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89 | '4バイト文字の始まり
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90 | last = 4
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91 | buffer = b And &h0F
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92 | state++
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93 | Else
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94 | '現在のUTF-8は4バイトを超える表現を認めていない。
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95 | dst.Add(&hFFFD As WCHAR)
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96 | End If
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97 | Else
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98 | If &h80 <= b And b < &hC0 Then
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99 | 'マルチバイト文字の2バイト目以降
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100 | buffer <<= 6
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101 | buffer Or= b And &h3F
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102 | state++
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103 | If state = last Then '最終バイトに到達
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104 | If state = 2 And buffer >= &h80 Then
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105 | dst.Add(buffer As WCHAR)
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106 | ElseIf state = 3 And buffer >= &h800 And buffer < &hD800 And &hE0000 >= buffer Then
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107 | dst.Add(buffer As WCHAR)
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108 | ElseIf state = 4 And buffer <= &h10FFFF Then
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109 | buffer -= &h10000
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110 | dst.Add((&hD800 Or (buffer >> 10)) As WCHAR)
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111 | dst.Add((&hDC00 Or (buffer And &h3FF)) As WCHAR)
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112 | Else
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113 | '最短形式でないもの、または4バイト形式で10FFFFを超えるコードポイントのもの
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114 | dst.Add(&hfffd As WCHAR)
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115 | End If
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116 | state = 0
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117 | End If
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118 | Else
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119 | 'マルチバイト文字の途中なのに、それ以外のバイトが現れた場合
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120 | dst.Add(&hFFFD As WCHAR)
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121 | state = 0
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122 | End If
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123 | End If
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124 | Next
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125 | DecodeImpl = True
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126 | End Function
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127 |
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128 | Private
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129 | buffer As DWord
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130 | state As Long
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131 | last As Long
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132 | End Class
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133 |
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134 | End Namespace 'Detail
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135 |
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136 |
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137 | /*!
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138 | @brief UTF-8用のEncoding
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139 | @date 2007/12/21
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140 | @auther Egtra
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141 | */
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142 | Class UTF8Encoding
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143 | Inherits Encoding
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144 | Public
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145 | Override Function Clone() As Object
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146 | Clone = New UTF8Encoding
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147 | End Function
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148 |
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149 | Override Function GetDecoder() As Decoder
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150 | GetDecoder = New Detail.UTF8Decoder
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151 | End Function
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152 |
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153 | Override Function GetEncoder() As Encoder
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154 | GetEncoder = New Detail.UTF8Encoder
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155 | End Function
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156 |
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157 | Override Function GetMaxByteCount(charCount As Long) As Long
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158 | GetMaxByteCount = charCount * 3
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159 | '全てがUTF-8で3バイトになる文字の場合が最大。
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160 |
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161 | 'なお、UTF-8で4バイトになる列は、UTF-16だとサロゲートペアで表現するので、
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162 | '1単位あたりでは2バイトしか食わないことになり、最大ではない。
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163 | End Function
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164 |
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165 | Override Function GetMaxCharCount(byteCount As Long) As Long
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166 | '全てU+7F以下の文字だけだった場合
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167 | GetMaxCharCount = byteCount
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168 | End Function
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169 |
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170 | Override Function GetPreamble() As *Byte
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171 | Return bom
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172 | End Function
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173 |
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174 | Override Function GetPreambleLength() As Long
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175 | Return Len(bom)
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176 | End Function
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177 | /*
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178 | Override Function BodyName() As String
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179 | Return "utf-8"
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180 | End Function
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181 |
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182 | Override Function HeaderName() As String
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183 | Return "utf-8"
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184 | End Function
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185 |
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186 | Override Function EncodingName() As String
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187 | Return "UTF-8"
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188 | End Function
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189 |
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190 | Override Function WebName() As String
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191 | Return "utf-8"
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192 | End Function
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193 |
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194 | Override Function IsSingleByte() As Boolean
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195 | Return False
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196 | End Function
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197 | */
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198 |
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199 | Private
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200 | Static bom[2] = [&hEF, &hBB, &hBF] As Byte
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201 | End Class
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202 |
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203 | End Namespace 'Text
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204 | End Namespace 'System
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