Complex classes like Decoder often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Decoder, and based on these observations, apply Extract Interface, too.
1 | <?php |
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16 | final class Decoder |
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17 | { |
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18 | /** @var string */ |
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19 | private $data = ''; |
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20 | |||
21 | /** @var int */ |
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22 | private $offset = 0; |
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23 | |||
24 | 62 | public function decode(string $data) |
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31 | |||
32 | 62 | private function parse() |
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33 | { |
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34 | 62 | if (!isset($this->data[$this->offset])) { |
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35 | throw InsufficientData::fromOffset($this->data, $this->offset, 1); |
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36 | } |
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37 | |||
38 | 62 | $byte = ORD[$this->data[$this->offset++]]; |
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39 | |||
40 | 62 | if ($byte < 0xc0) { |
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41 | // positive fixint |
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42 | 14 | if ($byte < 0x80) { |
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43 | 11 | return $byte; |
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44 | } |
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45 | // fixmap |
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46 | 6 | if ($byte < 0x90) { |
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47 | 2 | return $this->decodeMap($byte & 0xf); |
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48 | } |
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49 | // fixarray |
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50 | 4 | if ($byte < 0xa0) { |
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51 | 2 | return $this->decodeArray($byte & 0x0f); |
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52 | } |
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53 | // fixstr |
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54 | 2 | return $this->decodeStr($byte & 0x1f); |
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55 | } |
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56 | // negative fixint |
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57 | 54 | if ($byte > 0xdf) { |
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58 | 2 | return $byte - 0x100; |
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59 | } |
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60 | |||
61 | 52 | switch ($byte) { |
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62 | 52 | case 0xc0: return null; |
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63 | 51 | case 0xc2: return false; |
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64 | 50 | case 0xc3: return true; |
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65 | |||
66 | // bin 8/16/32 |
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67 | 48 | case 0xc4: return $this->decodeStr($this->decodeUint8()); |
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68 | 48 | case 0xc5: return $this->decodeStr($this->decodeUint16()); |
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69 | 48 | case 0xc6: return $this->decodeStr($this->decodeUint32()); |
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70 | |||
71 | // float 32/64 |
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72 | 48 | case 0xca: return $this->decodeFloat32(); |
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73 | 44 | case 0xcb: return $this->decodeFloat64(); |
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74 | |||
75 | // uint 8/16/32/64 |
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76 | 38 | case 0xcc: return $this->decodeUint8(); |
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77 | 36 | case 0xcd: return $this->decodeUint16(); |
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78 | 34 | case 0xce: return $this->decodeUint32(); |
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79 | 32 | case 0xcf: return $this->decodeUint64(); |
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80 | |||
81 | // int 8/16/32/64 |
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82 | 30 | case 0xd0: return $this->decodeInt8(); |
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83 | 28 | case 0xd1: return $this->decodeInt16(); |
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84 | 26 | case 0xd2: return $this->decodeInt32(); |
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85 | 24 | case 0xd3: return $this->decodeInt64(); |
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86 | |||
87 | // str 8/16/32 |
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88 | 21 | case 0xd9: return $this->decodeStr($this->decodeUint8()); |
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89 | 19 | case 0xda: return $this->decodeStr($this->decodeUint16()); |
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90 | 17 | case 0xdb: return $this->decodeStr($this->decodeUint32()); |
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91 | |||
92 | // array 16/32 |
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93 | 16 | case 0xdc: return $this->decodeArray($this->decodeUint16()); |
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94 | 14 | case 0xdd: return $this->decodeArray($this->decodeUint32()); |
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95 | |||
96 | // map 16/32 |
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97 | 13 | case 0xde: return $this->decodeMap($this->decodeUint16()); |
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98 | 11 | case 0xdf: return $this->decodeMap($this->decodeUint32()); |
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99 | |||
100 | // fixext 1/2/4/8/16 |
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101 | 10 | case 0xd4: return $this->decodeExt(1); |
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102 | 9 | case 0xd5: return $this->decodeExt(2); |
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103 | 8 | case 0xd6: return $this->decodeExt(4); |
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104 | 7 | case 0xd7: return $this->decodeExt(8); |
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105 | 6 | case 0xd8: return $this->decodeExt(16); |
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106 | |||
107 | // ext 8/16/32 |
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108 | 5 | case 0xc7: return $this->decodeExt($this->decodeUint8()); |
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109 | 4 | case 0xc8: return $this->decodeExt($this->decodeUint16()); |
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110 | 2 | case 0xc9: return $this->decodeExt($this->decodeUint32()); |
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111 | } |
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112 | |||
113 | 1 | throw UnknownByteHeader::fromOffset($byte, $this->offset); |
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114 | } |
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115 | |||
116 | 4 | private function decodeFloat32(): float |
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117 | { |
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118 | 4 | if (!isset($this->data[$this->offset + 3])) { |
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119 | throw InsufficientData::fromOffset($this->data, $this->offset, 4); |
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120 | } |
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121 | |||
122 | 4 | $num = ORD[$this->data[$this->offset++]] * 0x1000000 |
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123 | 4 | | ORD[$this->data[$this->offset++]] << 16 |
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124 | 4 | | ORD[$this->data[$this->offset++]] << 8 |
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125 | 4 | | ORD[$this->data[$this->offset++]]; |
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126 | |||
127 | 4 | return toFloat($num); |
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128 | } |
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129 | |||
130 | 6 | private function decodeFloat64(): float |
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131 | { |
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132 | 6 | if (!isset($this->data[$this->offset + 7])) { |
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133 | throw InsufficientData::fromOffset($this->data, $this->offset, 8); |
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134 | } |
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135 | |||
136 | 6 | $x = ORD[$this->data[$this->offset++]] * 0x1000000 |
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137 | 6 | | ORD[$this->data[$this->offset++]] << 16 |
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138 | 6 | | ORD[$this->data[$this->offset++]] << 8 |
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139 | 6 | | ORD[$this->data[$this->offset++]]; |
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140 | |||
141 | 6 | $y = ORD[$this->data[$this->offset++]] * 0x1000000 |
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142 | 6 | | ORD[$this->data[$this->offset++]] << 16 |
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143 | 6 | | ORD[$this->data[$this->offset++]] << 8 |
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144 | 6 | | ORD[$this->data[$this->offset++]]; |
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145 | |||
146 | 6 | return toDouble($y, $x); |
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147 | } |
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148 | |||
149 | 7 | private function decodeUint8(): int |
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150 | { |
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151 | 7 | if (!isset($this->data[$this->offset])) { |
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152 | throw InsufficientData::fromOffset($this->data, $this->offset, 1); |
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153 | } |
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154 | |||
155 | 7 | return ORD($this->data[$this->offset++]); |
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156 | } |
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157 | |||
158 | 11 | private function decodeUint16(): int |
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159 | { |
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160 | 11 | if (!isset($this->data[$this->offset + 1])) { |
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161 | throw InsufficientData::fromOffset($this->data, $this->offset, 2); |
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162 | } |
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163 | |||
164 | 11 | return ORD[$this->data[$this->offset++]] << 8 |
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165 | 11 | | ORD[$this->data[$this->offset++]]; |
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166 | } |
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167 | |||
168 | 6 | private function decodeUint32(): int |
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169 | { |
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170 | 6 | if (!isset($this->data[$this->offset + 3])) { |
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171 | throw InsufficientData::fromOffset($this->data, $this->offset, 4); |
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172 | } |
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173 | |||
174 | 6 | return ORD[$this->data[$this->offset++]] * 0x1000000 |
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175 | 6 | | ORD[$this->data[$this->offset++]] << 16 |
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176 | 6 | | ORD[$this->data[$this->offset++]] << 8 |
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177 | 6 | | ORD[$this->data[$this->offset++]]; |
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178 | } |
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179 | |||
180 | 2 | private function decodeUint64() |
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181 | { |
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182 | 2 | if (!isset($this->data[$this->offset + 7])) { |
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183 | throw InsufficientData::fromOffset($this->data, $this->offset, 8); |
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184 | } |
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185 | |||
186 | 2 | $num = (ORD[$this->data[$this->offset++]] * 0x1000000 |
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187 | 2 | | ORD[$this->data[$this->offset++]] << 16 |
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188 | 2 | | ORD[$this->data[$this->offset++]] << 8 |
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189 | 2 | | ORD[$this->data[$this->offset++]]) * 0x100000000 |
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190 | 2 | | ORD[$this->data[$this->offset++]] * 0x1000000 |
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191 | 2 | | ORD[$this->data[$this->offset++]] << 16 |
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192 | 2 | | ORD[$this->data[$this->offset++]] << 8 |
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193 | 2 | | ORD[$this->data[$this->offset++]]; |
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194 | |||
195 | 2 | return $num < 0 ? sprintf('%u', $num) : $num; |
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196 | } |
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197 | |||
198 | 11 | private function decodeInt8(): int |
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199 | { |
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200 | 11 | if (!isset($this->data[$this->offset])) { |
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201 | throw InsufficientData::fromOffset($this->data, $this->offset, 1); |
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202 | } |
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203 | |||
204 | 11 | $num = ORD[$this->data[$this->offset++]]; |
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205 | |||
206 | 11 | return $num & 0x80 ? $num - 0x100 : $num; |
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207 | } |
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208 | |||
209 | 2 | private function decodeInt16(): int |
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210 | { |
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211 | 2 | if (!isset($this->data[$this->offset + 1])) { |
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212 | throw InsufficientData::fromOffset($this->data, $this->offset, 2); |
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213 | } |
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214 | |||
215 | 2 | $num = ORD[$this->data[$this->offset++]] << 8 |
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216 | 2 | | ORD[$this->data[$this->offset++]]; |
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217 | |||
218 | 2 | return $num & 0x8000 ? $num - 0x10000 : $num; |
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219 | } |
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220 | |||
221 | 2 | private function decodeInt32(): int |
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222 | { |
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223 | 2 | if (!isset($this->data[$this->offset + 3])) { |
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224 | throw InsufficientData::fromOffset($this->data, $this->offset, 4); |
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225 | } |
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226 | |||
227 | 2 | $num = ORD[$this->data[$this->offset++]] * 0x1000000 |
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228 | 2 | | ORD[$this->data[$this->offset++]] << 16 |
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229 | 2 | | ORD[$this->data[$this->offset++]] << 8 |
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230 | 2 | | ORD[$this->data[$this->offset++]]; |
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231 | |||
232 | 2 | return $num & 0x80000000 ? $num - 0x100000000 : $num; |
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233 | } |
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234 | |||
235 | 3 | private function decodeInt64(): int |
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236 | { |
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237 | 3 | if (!isset($this->data[$this->offset + 7])) { |
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238 | throw InsufficientData::fromOffset($this->data, $this->offset, 8); |
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239 | } |
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240 | |||
241 | 3 | $num = ORD[$this->data[$this->offset++]]; |
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242 | |||
243 | 3 | $negate = ($num & 0x80) === 0x80; |
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244 | |||
245 | 3 | if ($negate) { |
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246 | 2 | $num = (($num ^ 0xff) * 0x100000000000000) |
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247 | 2 | | (ORD[$this->data[$this->offset++]] ^ 0xff) * 0x1000000000000 |
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248 | 2 | | (ORD[$this->data[$this->offset++]] ^ 0xff) * 0x10000000000 |
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249 | 2 | | (ORD[$this->data[$this->offset++]] ^ 0xff) * 0x100000000 |
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250 | 2 | | (ORD[$this->data[$this->offset++]] ^ 0xff) * 0x1000000 |
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251 | 2 | | (ORD[$this->data[$this->offset++]] ^ 0xff) * 0x10000 |
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252 | 2 | | (ORD[$this->data[$this->offset++]] ^ 0xff) * 0x100 |
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253 | 2 | | ORD[$this->data[$this->offset++]] ^ 0xff; |
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254 | |||
255 | 2 | return ~$num; |
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256 | } |
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257 | |||
258 | 1 | $num = ($num * 0x100000000000000) |
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259 | 1 | | ORD[$this->data[$this->offset++]] * 0x1000000000000 |
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260 | 1 | | ORD[$this->data[$this->offset++]] * 0x10000000000 |
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261 | 1 | | ORD[$this->data[$this->offset++]] * 0x100000000 |
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262 | 1 | | ORD[$this->data[$this->offset++]] * 0x1000000 |
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263 | 1 | | ORD[$this->data[$this->offset++]] * 0x10000 |
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264 | 1 | | ORD[$this->data[$this->offset++]] * 0x100 |
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265 | 1 | | ORD[$this->data[$this->offset++]]; |
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266 | |||
267 | 1 | return $num; |
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268 | } |
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269 | |||
270 | 7 | private function decodeStr(int $length): string |
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271 | { |
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272 | 7 | if (0 === $length) { |
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273 | 1 | return ''; |
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274 | } |
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275 | |||
276 | 6 | if (!isset($this->data[$this->offset + $length - 1])) { |
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277 | throw InsufficientData::fromOffset($this->data, $this->offset, $length); |
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278 | } |
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279 | |||
280 | 6 | $str = substr($this->data, $this->offset++, $length); |
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281 | 6 | $this->offset += $length; |
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282 | |||
283 | 6 | return $str; |
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284 | } |
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285 | |||
286 | 5 | private function decodeArray(int $size): array |
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295 | |||
296 | 5 | private function decodeMap(int $size): array |
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305 | |||
306 | 9 | private function decodeExt(int $length): Ext |
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307 | { |
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308 | 9 | if (!isset($this->data[$this->offset + $length - 1])) { |
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309 | throw InsufficientData::fromOffset($this->data, $this->offset, $length); |
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310 | } |
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311 | |||
312 | 9 | $type = $this->decodeInt8(); |
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313 | |||
314 | 9 | $data = substr($this->data, $this->offset++, $length); |
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315 | 9 | $this->offset += $length; |
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316 | |||
317 | 9 | return Ext::make($type, $data); |
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319 | } |
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320 |
Let’s assume that you have a directory layout like this:
and let’s assume the following content of
Bar.php
:If both files
OtherDir/Foo.php
andSomeDir/Foo.php
are loaded in the same runtime, you will see a PHP error such as the following:PHP Fatal error: Cannot use SomeDir\Foo as Foo because the name is already in use in OtherDir/Foo.php
However, as
OtherDir/Foo.php
does not necessarily have to be loaded and the error is only triggered if it is loaded beforeOtherDir/Bar.php
, this problem might go unnoticed for a while. In order to prevent this error from surfacing, you must import the namespace with a different alias: