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      1 <?php
      2 /*
      3  * Copyright 2015 Google Inc.
      4  *
      5  * Licensed under the Apache License, Version 2.0 (the "License");
      6  * you may not use this file except in compliance with the License.
      7  * You may obtain a copy of the License at
      8  *
      9  *     http://www.apache.org/licenses/LICENSE-2.0
     10  *
     11  * Unless required by applicable law or agreed to in writing, software
     12  * distributed under the License is distributed on an "AS IS" BASIS,
     13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     14  * See the License for the specific language governing permissions and
     15  * limitations under the License.
     16  */
     17 
     18 namespace Google\FlatBuffers;
     19 
     20 abstract class Table
     21 {
     22     /**
     23      * @var int $bb_pos
     24      */
     25     protected $bb_pos;
     26     /**
     27      * @var ByteBuffer $bb
     28      */
     29     protected $bb;
     30 
     31     public function __construct()
     32     {
     33     }
     34 
     35     public function setByteBufferPos($pos)
     36     {
     37         $this->bb_pos = $pos;
     38     }
     39 
     40     public function setByteBuffer($bb)
     41     {
     42         $this->bb = $bb;
     43     }
     44 
     45     /**
     46      * returns actual vtable offset
     47      *
     48      * @param $vtable_offset
     49      * @return int offset > 0 means exist value. 0 means not exist
     50      */
     51     protected function __offset($vtable_offset)
     52     {
     53         $vtable = $this->bb_pos - $this->bb->getInt($this->bb_pos);
     54         return $vtable_offset < $this->bb->getShort($vtable) ? $this->bb->getShort($vtable + $vtable_offset) : 0;
     55     }
     56 
     57     /**
     58      * @param $offset
     59      * @return mixed
     60      */
     61     protected function __indirect($offset)
     62     {
     63         return $offset + $this->bb->getInt($offset);
     64     }
     65 
     66     /**
     67      * fetch utf8 encoded string.
     68      *
     69      * @param $offset
     70      * @return string
     71      */
     72     protected function __string($offset)
     73     {
     74         $offset += $this->bb->getInt($offset);
     75         $len = $this->bb->getInt($offset);
     76         $startPos = $offset + Constants::SIZEOF_INT;
     77         return substr($this->bb->_buffer, $startPos, $len);
     78     }
     79 
     80     /**
     81      * @param $offset
     82      * @return int
     83      */
     84     protected function __vector_len($offset)
     85     {
     86         $offset += $this->bb_pos;
     87         $offset += $this->bb->getInt($offset);
     88         return $this->bb->getInt($offset);
     89     }
     90 
     91     /**
     92      * @param $offset
     93      * @return int
     94      */
     95     protected function __vector($offset)
     96     {
     97         $offset += $this->bb_pos;
     98         // data starts after the length
     99         return $offset + $this->bb->getInt($offset) + Constants::SIZEOF_INT;
    100     }
    101 
    102     protected function __vector_as_bytes($vector_offset, $elem_size=1)
    103     {
    104         $o = $this->__offset($vector_offset);
    105         if ($o == 0) {
    106             return null;
    107         }
    108 
    109         return substr($this->bb->_buffer, $this->__vector($o), $this->__vector_len($o) * $elem_size);
    110     }
    111 
    112     /**
    113      * @param Table $table
    114      * @param int $offset
    115      * @return Table
    116      */
    117     protected function __union($table, $offset)
    118     {
    119         $offset += $this->bb_pos;
    120         $table->setByteBufferPos($offset + $this->bb->getInt($offset));
    121         $table->setByteBuffer($this->bb);
    122         return $table;
    123     }
    124 
    125     /**
    126      * @param ByteBuffer $bb
    127      * @param string $ident
    128      * @return bool
    129      * @throws \ArgumentException
    130      */
    131     protected static function __has_identifier($bb, $ident)
    132     {
    133         if (strlen($ident) != Constants::FILE_IDENTIFIER_LENGTH) {
    134             throw new \ArgumentException("FlatBuffers: file identifier must be length "  . Constants::FILE_IDENTIFIER_LENGTH);
    135         }
    136 
    137         for ($i = 0; $i < 4; $i++) {
    138             if ($ident[$i] != $bb->get($bb->getPosition() + Constants::SIZEOF_INT + $i)) {
    139                 return false;
    140             }
    141         }
    142 
    143         return true;
    144     }
    145 }
    146