1 | <?php |
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2 | |||||
3 | namespace Violet\StreamingJsonEncoder; |
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4 | |||||
5 | use Psr\Http\Message\StreamInterface; |
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6 | |||||
7 | /** |
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8 | * Provides a http stream interface for encoding JSON. |
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9 | * |
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10 | * @author Riikka Kalliomäki <[email protected]> |
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11 | * @copyright Copyright (c) 2016-2020 Riikka Kalliomäki |
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12 | * @license http://opensource.org/licenses/mit-license.php MIT License |
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13 | */ |
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14 | class JsonStream implements StreamInterface |
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15 | { |
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16 | /** @var BufferJsonEncoder|null The encoder used to produce the JSON stream or null once closed */ |
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17 | private $encoder; |
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18 | |||||
19 | /** @var int The current position of the cursor in the JSON stream */ |
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20 | private $cursor; |
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21 | |||||
22 | /** @var string|null Buffered output from encoding the value as JSON or null when at EOF */ |
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23 | private $buffer; |
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24 | |||||
25 | /** |
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26 | * JsonStream constructor. |
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27 | * @param BufferJsonEncoder|mixed $value A JSON encoder to use or a value to encode |
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28 | */ |
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29 | public function __construct($value) |
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30 | { |
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31 | if (!$value instanceof BufferJsonEncoder) { |
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32 | $value = (new BufferJsonEncoder($value)) |
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33 | ->setOptions(JSON_PARTIAL_OUTPUT_ON_ERROR) |
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34 | ->setIndent(0); |
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35 | } |
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36 | |||||
37 | $this->encoder = $value; |
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38 | $this->rewind(); |
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39 | } |
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40 | |||||
41 | /** |
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42 | * Returns the JSON encoder used for the JSON stream. |
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43 | * @return BufferJsonEncoder The currently used JSON encoder |
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44 | * @throws \RuntimeException If the stream has been closed |
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45 | */ |
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46 | private function getEncoder() |
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47 | { |
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48 | if (!$this->encoder instanceof BufferJsonEncoder) { |
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49 | throw new \RuntimeException('Cannot operate on a closed JSON stream'); |
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50 | } |
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51 | |||||
52 | return $this->encoder; |
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53 | } |
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54 | |||||
55 | /** |
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56 | * Returns the entire JSON stream as a string. |
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57 | * |
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58 | * Note that this operation performs rewind operation on the JSON encoder. Whether |
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59 | * this works or not is dependant on the underlying value being encoded. An empty |
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60 | * string is returned if the value cannot be encoded. |
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61 | * |
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62 | * @return string The entire JSON stream as a string |
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63 | */ |
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64 | public function __toString() |
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65 | { |
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66 | try { |
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67 | $this->rewind(); |
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68 | return $this->getContents(); |
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69 | } catch (\Exception $exception) { |
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70 | return ''; |
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71 | } |
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72 | } |
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73 | |||||
74 | /** |
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75 | * Frees the JSON encoder from memory and prevents further reading from the JSON stream. |
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76 | */ |
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77 | public function close() |
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78 | { |
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79 | $this->encoder = null; |
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80 | } |
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81 | |||||
82 | /** |
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83 | * Detaches the underlying PHP resource from the stream and returns it. |
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84 | * @return null Always returns null as no underlying PHP resource exists |
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85 | */ |
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86 | public function detach() |
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87 | { |
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88 | return null; |
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89 | } |
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90 | |||||
91 | /** |
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92 | * Returns the total size of the JSON stream. |
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93 | * @return null Always returns null as the total size cannot be determined |
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94 | */ |
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95 | public function getSize() |
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96 | { |
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97 | return null; |
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98 | } |
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99 | |||||
100 | /** |
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101 | * Returns the current position of the cursor in the JSON stream. |
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102 | * @return int Current position of the cursor |
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103 | */ |
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104 | public function tell() |
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105 | { |
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106 | $this->getEncoder(); |
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107 | return $this->cursor; |
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108 | } |
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109 | |||||
110 | /** |
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111 | * Tells if there are no more bytes to read from the JSON stream. |
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112 | * @return bool True if there are no more bytes to read, false if there are |
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113 | */ |
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114 | public function eof() |
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115 | { |
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116 | return $this->buffer === null; |
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117 | } |
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118 | |||||
119 | /** |
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120 | * Tells if the JSON stream is seekable or not. |
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121 | * @return bool Always returns true as JSON streams as always seekable |
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122 | */ |
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123 | public function isSeekable() |
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124 | { |
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125 | return true; |
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126 | } |
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127 | |||||
128 | /** |
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129 | * Seeks the given cursor position in the JSON stream. |
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130 | * |
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131 | * If the provided seek position is less than the current cursor position, a rewind |
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132 | * operation is performed on the underlying JSON encoder. Whether this works or not |
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133 | * depends on whether the encoded value supports rewinding. |
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134 | * |
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135 | * Note that since it's not possible to determine the end of the JSON stream without |
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136 | * encoding the entire value, it's not possible to set the cursor using SEEK_END |
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137 | * constant and doing so will result in an exception. |
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138 | * |
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139 | * @param int $offset The offset for the cursor |
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140 | * @param int $whence Either SEEK_CUR or SEEK_SET to determine new cursor position |
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141 | * @throws \RuntimeException If SEEK_END is used to determine the cursor position |
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142 | */ |
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143 | public function seek($offset, $whence = SEEK_SET) |
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144 | { |
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145 | $position = $this->calculatePosition($offset, $whence); |
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146 | |||||
147 | if (!isset($this->cursor) || $position < $this->cursor) { |
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148 | $this->getEncoder()->rewind(); |
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149 | $this->buffer = ''; |
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150 | $this->cursor = 0; |
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151 | } |
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152 | |||||
153 | $this->forward($position); |
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154 | } |
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155 | |||||
156 | /** |
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157 | * Calculates new position for the cursor based on offset and whence. |
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158 | * @param int $offset The cursor offset |
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159 | * @param int $whence One of the SEEK_* constants |
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160 | * @return int The new cursor position |
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161 | * @throws \RuntimeException If SEEK_END is used to determine the cursor position |
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162 | */ |
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163 | private function calculatePosition($offset, $whence) |
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164 | { |
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165 | if ($whence === SEEK_CUR) { |
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166 | return max(0, $this->cursor + (int) $offset); |
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167 | } elseif ($whence === SEEK_SET) { |
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168 | return max(0, (int) $offset); |
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169 | } elseif ($whence === SEEK_END) { |
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170 | throw new \RuntimeException('Cannot set cursor position from the end of a JSON stream'); |
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171 | } |
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172 | |||||
173 | throw new \InvalidArgumentException("Invalid cursor relative position '$whence'"); |
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174 | } |
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175 | |||||
176 | /** |
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177 | * Forwards the JSON stream reading cursor to the given position or to the end of stream. |
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178 | * @param int $position The new position of the cursor |
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179 | */ |
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180 | private function forward($position) |
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181 | { |
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182 | $encoder = $this->getEncoder(); |
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183 | |||||
184 | while ($this->cursor < $position) { |
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185 | $length = strlen($this->buffer); |
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186 | |||||
187 | if ($this->cursor + $length > $position) { |
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188 | $this->buffer = substr($this->buffer, $position - $this->cursor); |
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189 | $this->cursor = $position; |
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190 | break; |
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191 | } |
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192 | |||||
193 | $this->cursor += $length; |
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194 | $this->buffer = ''; |
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195 | |||||
196 | if (!$encoder->valid()) { |
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197 | $this->buffer = null; |
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198 | break; |
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199 | } |
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200 | |||||
201 | $this->buffer = $encoder->current(); |
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202 | $encoder->next(); |
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203 | } |
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204 | } |
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205 | |||||
206 | /** |
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207 | * Seeks the beginning of the JSON stream. |
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208 | * |
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209 | * If the encoding has already been started, rewinding the encoder may not work, |
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210 | * if the underlying value being encoded does not support rewinding. |
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211 | */ |
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212 | public function rewind() |
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213 | { |
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214 | $this->seek(0); |
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215 | } |
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216 | |||||
217 | /** |
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218 | * Tells if the JSON stream is writable or not. |
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219 | * @return bool Always returns false as JSON streams are never writable |
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220 | */ |
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221 | public function isWritable() |
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222 | { |
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223 | return false; |
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224 | } |
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225 | |||||
226 | /** |
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227 | * Writes the given bytes to the JSON stream. |
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228 | * |
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229 | * As the JSON stream does not represent a writable stream, this method will |
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230 | * always throw a runtime exception. |
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231 | * |
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232 | * @param string $string The bytes to write |
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233 | * @return int The number of bytes written |
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234 | * @throws \RuntimeException Always throws a runtime exception |
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235 | */ |
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236 | public function write($string) |
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237 | { |
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238 | throw new \RuntimeException('Cannot write to a JSON stream'); |
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239 | } |
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240 | |||||
241 | /** |
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242 | * Tells if the JSON stream is readable or not. |
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243 | * @return bool Always returns true as JSON streams are always readable |
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244 | */ |
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245 | public function isReadable() |
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246 | { |
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247 | return true; |
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248 | } |
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249 | |||||
250 | /** |
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251 | * Returns the given number of bytes from the JSON stream. |
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252 | * |
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253 | * The underlying value is encoded into JSON until enough bytes have been |
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254 | * generated to fulfill the requested number of bytes. The extraneous bytes are |
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255 | * then buffered for the next read from the JSON stream. The stream may return |
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256 | * fewer number of bytes if the entire value has been encoded and there are no |
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257 | * more bytes to return. |
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258 | * |
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259 | * @param int $length The number of bytes to return |
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260 | * @return string The bytes read from the JSON stream |
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261 | */ |
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262 | public function read($length) |
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263 | { |
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264 | if ($this->eof()) { |
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265 | return ''; |
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266 | } |
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267 | |||||
268 | $length = max(0, (int) $length); |
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269 | $encoder = $this->getEncoder(); |
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270 | |||||
271 | while (strlen($this->buffer) < $length && $encoder->valid()) { |
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272 | $this->buffer .= $encoder->current(); |
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273 | $encoder->next(); |
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274 | } |
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275 | |||||
276 | if (strlen($this->buffer) > $length || $encoder->valid()) { |
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277 | $output = substr($this->buffer, 0, $length); |
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278 | $this->buffer = substr($this->buffer, $length); |
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279 | } else { |
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280 | $output = (string) $this->buffer; |
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281 | $this->buffer = null; |
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282 | } |
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283 | |||||
284 | $this->cursor += strlen($output); |
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285 | |||||
286 | return $output; |
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287 | } |
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288 | |||||
289 | /** |
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290 | * Returns the remaining bytes from the JSON stream. |
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291 | * @return string The remaining bytes from JSON stream |
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292 | */ |
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293 | public function getContents() |
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294 | { |
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295 | if ($this->eof()) { |
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296 | return ''; |
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297 | } |
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298 | |||||
299 | $encoder = $this->getEncoder(); |
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300 | $output = $this->buffer; |
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301 | |||||
302 | while ($encoder->valid()) { |
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303 | $output .= $encoder->current(); |
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304 | $encoder->next(); |
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305 | } |
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306 | |||||
307 | $this->cursor += strlen($output); |
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308 | $this->buffer = null; |
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309 | |||||
310 | return $output; |
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311 | } |
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312 | |||||
313 | /** |
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314 | * Returns the metadata related to the JSON stream. |
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315 | * |
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316 | * No underlying PHP resource exists for the stream, but this method will |
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317 | * still return relevant information regarding the stream that is similar |
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318 | * to PHP stream meta data. |
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319 | * |
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320 | * @param string|null $key The key of the value to return |
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321 | * @return array|mixed|null The meta data array, a specific value or null if not defined |
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322 | */ |
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323 | public function getMetadata($key = null) |
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324 | { |
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325 | $meta = [ |
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326 | 'timed_out' => false, |
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327 | 'blocked' => true, |
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328 | 'eof' => $this->eof(), |
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329 | 'unread_bytes' => strlen($this->buffer), |
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0 ignored issues
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show
It seems like
$this->buffer can also be of type null ; however, parameter $string of strlen() does only seem to accept string , maybe add an additional type check?
(
Ignorable by Annotation
)
If this is a false-positive, you can also ignore this issue in your code via the
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330 | 'stream_type' => get_class($this->encoder), |
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It seems like
$this->encoder can also be of type null ; however, parameter $object of get_class() does only seem to accept object , maybe add an additional type check?
(
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)
If this is a false-positive, you can also ignore this issue in your code via the
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331 | 'wrapper_type' => 'OBJECT', |
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332 | 'wrapper_data' => [ |
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333 | 'step' => $this->encoder->key(), |
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0 ignored issues
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The method
key() does not exist on null .
(
Ignorable by Annotation
)
If this is a false-positive, you can also ignore this issue in your code via the
This check looks for calls to methods that do not seem to exist on a given type. It looks for the method on the type itself as well as in inherited classes or implemented interfaces. This is most likely a typographical error or the method has been renamed.
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334 | 'errors' => $this->encoder->getErrors(), |
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335 | ], |
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336 | 'mode' => 'r', |
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337 | 'seekable' => true, |
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338 | 'uri' => '', |
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339 | ]; |
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340 | |||||
341 | return $key === null ? $meta : (isset($meta[$key]) ? $meta[$key] : null); |
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342 | } |
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343 | } |
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344 |