(PHP) add experimental support for PHP language.

* codegen for all basic features: WIP (probably implemented all basic feature)
* JSON parsing: NO
* Simple mutation: NO
* Reflection: NO
* Buffer verifier: NO (will be add later)
* Testing: basic: Yes
* Testing: fuzz: Yes
* Performance: Not bad
* Platform: Supported Linux, OS X, Windows (has 32bit integer limitation)
* Engine Unity: No

flatc --php monster_test.fbs

  <?php
  //include neccessary files.
  $fbb = new Google\FlatBuffers\FlatBufferBuilder(1);
  $str = $fbb->createString("monster");
  \MyGame\Example\Monster::startMonster($fbb);
  \MyGame\Example\Monster::addHp($fbb, 80);
  \MyGame\Example\Monster::addName($fbb, $str);
  $mon = \MyGame\Example\Monster::endMonster($fbb);
  $fbb->finish($mon);
  echo $fbb->sizedByteArray();

PHP 5.4 higher

Currently, we do not register this library to packagist as still experimental and versioning problem.
If you intended to use flatbuffers with composer. add repostiories section to composer.json like below.

  "repositories": [{
    "type": "vcs",
    "url": "https://github.com/google/flatbuffers"
  }],

 and just put google/flatbuffers.

  "require": {
    "google/flatbuffers": "*"
  }

* PHP's integer is platform dependant. we strongly recommend use 64bit machine
  and don't use uint, ulong types as prevent overflow issue.
  ref: http://php.net/manual/en/language.types.integer.php

* php don't support float type. floating point numbers are always parsed as double precision internally.
  ref: http://php.net/manual/en/language.types.float.php

* ByteBuffer is little bit slow implemnentation due to many chr/ord function calls. Especially encoding objects.
  This is expected performance as PHP5 has parsing arguments overhead. probably we'll add C-extension.

Basically, PHP implementation respects Java and C# implementation.

Note: ByteBuffer and FlatBuffersBuilder class are not intended to use other purposes.
      we may change internal API foreseeable future.

PSR-2, PSR-4 standards.

Implemented simple assertion class (respect JavaScript testcase implementation) as we prefer small code base.
this also keeps CI iteration speed.

we'll choose phpunit or something when the test cases grown.

5 files changed, 1598 insertions, 0 deletions

diff --git a/php/ByteBuffer.php b/php/ByteBuffer.php
new file mode 100644
index 00000000..4a583b7a
--- /dev/null
+++ b/php/ByteBuffer.php
@@ -0,0 +1,495 @@
+<?php
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Google\FlatBuffers;
+
+class ByteBuffer
+{
+    /**
+     * @var string $_buffer;
+     */
+    public $_buffer;
+
+    /**
+     * @var int $_pos;
+     */
+    private $_pos;
+
+    /**
+     * @var bool $_is_little_endian
+     */
+    private static $_is_little_endian = null;
+
+    public static function wrap($bytes)
+    {
+        $bb = new ByteBuffer(0);
+        $bb->_buffer = $bytes;
+
+        return $bb;
+    }
+
+    /**
+     * @param $size
+     */
+    public function __construct($size)
+    {
+        $this->_buffer = str_repeat("\0", $size);
+    }
+
+    /**
+     * @return int
+     */
+    public function capacity()
+    {
+        return strlen($this->_buffer);
+    }
+
+    /**
+     * @return int
+     */
+    public function getPosition()
+    {
+        return $this->_pos;
+    }
+
+    /**
+     * @param $pos
+     */
+    public function setPosition($pos)
+    {
+        $this->_pos = $pos;
+    }
+
+    /**
+     *
+     */
+    public function reset()
+    {
+        $this->_pos = 0;
+    }
+
+    /**
+     * @return int
+     */
+    public function length()
+    {
+        return strlen($this->_buffer);
+    }
+
+    /**
+     * @return string
+     */
+    public function data()
+    {
+        return substr($this->_buffer, $this->_pos);
+    }
+
+    /**
+     * @return bool
+     */
+    public static function isLittleEndian()
+    {
+        if (ByteBuffer::$_is_little_endian === null) {
+            ByteBuffer::$_is_little_endian = unpack('S', "\x01\x00")[1] === 1;
+        }
+
+        return ByteBuffer::$_is_little_endian;
+    }
+
+    /**
+     * write little endian value to the buffer.
+     *
+     * @param $offset
+     * @param $count byte length
+     * @param $data actual values
+     */
+    public function writeLittleEndian($offset, $count, $data)
+    {
+        if (ByteBuffer::isLittleEndian()) {
+            for ($i = 0; $i < $count; $i++) {
+                $this->_buffer[$offset + $i] = chr($data >> $i * 8);
+            }
+        } else {
+            for ($i = 0; $i < $count; $i++) {
+                $this->_buffer[$offset + $count - 1 - $i] = chr($data >> $i * 8);
+            }
+        }
+    }
+
+    /**
+     * read little endian value from the buffer
+     *
+     * @param $offset
+     * @param $count acutal size
+     * @return int
+     */
+    public function readLittleEndian($offset, $count, $force_bigendian = false)
+    {
+        $this->assertOffsetAndLength($offset, $count);
+        $r = 0;
+
+        if (ByteBuffer::isLittleEndian() && $force_bigendian == false) {
+            for ($i = 0; $i < $count; $i++) {
+                $r |= ord($this->_buffer[$offset + $i]) << $i * 8;
+            }
+        } else {
+            for ($i = 0; $i < $count; $i++) {
+                $r |= ord($this->_buffer[$offset + $count -1 - $i]) << $i * 8;
+            }
+        }
+
+        return $r;
+    }
+
+    /**
+     * @param $offset
+     * @param $length
+     */
+    public function assertOffsetAndLength($offset, $length)
+    {
+        if ($offset < 0 ||
+            $offset >= strlen($this->_buffer) ||
+            $offset + $length > strlen($this->_buffer)) {
+            throw new \OutOfRangeException(sprintf("offset: %d, length: %d, buffer; %d", $offset, $length, strlen($this->_buffer)));
+        }
+    }
+
+    /**
+     * @param $offset
+     * @param $value
+     * @return mixed
+     */
+    public function putSbyte($offset, $value)
+    {
+        self::validateValue(-128, 127, $value, "sbyte");
+
+        $length = strlen($value);
+        $this->assertOffsetAndLength($offset, $length);
+        return $this->_buffer[$offset] = $value;
+    }
+
+    /**
+     * @param $offset
+     * @param $value
+     * @return mixed
+     */
+    public function putByte($offset, $value)
+    {
+        self::validateValue(0, 255, $value, "byte");
+
+        $length = strlen($value);
+        $this->assertOffsetAndLength($offset, $length);
+        return $this->_buffer[$offset] = $value;
+    }
+
+    /**
+     * @param $offset
+     * @param $value
+     */
+    public function put($offset, $value)
+    {
+        $length = strlen($value);
+        $this->assertOffsetAndLength($offset, $length);
+        for ($i = 0; $i < $length; $i++) {
+            $this->_buffer[$offset + $i] = $value[$i];
+        }
+    }
+
+    /**
+     * @param $offset
+     * @param $value
+     */
+    public function putShort($offset, $value)
+    {
+        self::validateValue(-32768, 32767, $value, "short");
+
+        $this->assertOffsetAndLength($offset, 2);
+        $this->writeLittleEndian($offset, 2, $value);
+    }
+
+    /**
+     * @param $offset
+     * @param $value
+     */
+    public function putUshort($offset, $value)
+    {
+        self::validateValue(0, 65535, $value, "short");
+
+        $this->assertOffsetAndLength($offset, 2);
+        $this->writeLittleEndian($offset, 2, $value);
+    }
+
+    /**
+     * @param $offset
+     * @param $value
+     */
+    public function putInt($offset, $value)
+    {
+        self::validateValue(~PHP_INT_MAX,  PHP_INT_MAX, $value, "int");
+
+        $this->assertOffsetAndLength($offset, 4);
+        $this->writeLittleEndian($offset, 4, $value);
+    }
+
+    /**
+     * @param $offset
+     * @param $value
+     */
+    public function putUint($offset, $value)
+    {
+        // NOTE: We can't put big integer value. this is PHP limitation.
+        self::validateValue(0,  PHP_INT_MAX, $value, "uint",  " php has big numbers limitation. check your PHP_INT_MAX");
+
+        $this->assertOffsetAndLength($offset, 4);
+        $this->writeLittleEndian($offset, 4, $value);
+    }
+
+    /**
+     * @param $offset
+     * @param $value
+     */
+    public function putLong($offset, $value)
+    {
+        // NOTE: We can't put big integer value. this is PHP limitation.
+        self::validateValue(~PHP_INT_MAX, PHP_INT_MAX, $value, "long",  " php has big numbers limitation. check your PHP_INT_MAX");
+
+        $this->assertOffsetAndLength($offset, 8);
+        $this->writeLittleEndian($offset, 8, $value);
+    }
+
+    /**
+     * @param $offset
+     * @param $value
+     */
+    public function putUlong($offset, $value)
+    {
+        // NOTE: We can't put big integer value. this is PHP limitation.
+        self::validateValue(0, PHP_INT_MAX, $value, "long", " php has big numbers limitation. check your PHP_INT_MAX");
+
+        $this->assertOffsetAndLength($offset, 8);
+        $this->writeLittleEndian($offset, 8, $value);
+    }
+
+    /**
+     * @param $offset
+     * @param $value
+     */
+    public function putFloat($offset, $value)
+    {
+        $this->assertOffsetAndLength($offset, 4);
+
+        $floathelper = pack("f", $value);
+        $v = unpack("V", $floathelper);
+        $this->writeLittleEndian($offset, 4, $v[1]);
+    }
+
+    /**
+     * @param $offset
+     * @param $value
+     */
+    public function putDouble($offset, $value)
+    {
+        $this->assertOffsetAndLength($offset, 8);
+
+        $floathelper = pack("d", $value);
+        $v = unpack("V*", $floathelper);
+
+        $this->writeLittleEndian($offset, 4, $v[1]);
+        $this->writeLittleEndian($offset + 4, 4, $v[2]);
+    }
+
+    /**
+     * @param $index
+     * @return mixed
+     */
+    public function getByte($index)
+    {
+        return ord($this->_buffer[$index]);
+    }
+
+    /**
+     * @param $index
+     * @return mixed
+     */
+    public function getSbyte($index)
+    {
+        $v = unpack("c", $this->_buffer[$index]);
+        return $v[1];
+    }
+
+    /**
+     * @param $buffer
+     */
+    public function getX(&$buffer)
+    {
+        for ($i = $this->_pos, $j = 0; $j < strlen($buffer); $i++, $j++) {
+            $buffer[$j] = $this->_buffer[$i];
+        }
+    }
+
+    /**
+     * @param $index
+     * @return mixed
+     */
+    public function get($index)
+    {
+        $this->assertOffsetAndLength($index, 1);
+        return $this->_buffer[$index];
+    }
+
+
+    /**
+     * @param $index
+     * @return mixed
+     */
+    public function getBool($index)
+    {
+        return (bool)ord($this->_buffer[$index]);
+    }
+
+    /**
+     * @param $index
+     * @return int
+     */
+    public function getShort($index)
+    {
+        $result = $this->readLittleEndian($index, 2);
+
+        return self::convertHelper(self::__SHORT, $result);
+    }
+
+    /**
+     * @param $index
+     * @return int
+     */
+    public function getUShort($index)
+    {
+        return $this->readLittleEndian($index, 2);
+    }
+
+    /**
+     * @param $index
+     * @return int
+     */
+    public function getInt($index)
+    {
+        $result = $this->readLittleEndian($index, 4);
+
+        return self::convertHelper(self::__INT, $result);
+    }
+
+    /**
+     * @param $index
+     * @return int
+     */
+    public function getUint($index)
+    {
+        return $this->readLittleEndian($index, 4);
+    }
+
+    /**
+     * @param $index
+     * @return int
+     */
+    public function getLong($index)
+    {
+        $result =  $this->readLittleEndian($index, 8);
+
+        return self::convertHelper(self::__LONG, $result);
+    }
+
+    /**
+     * @param $index
+     * @return int
+     */
+    public function getUlong($index)
+    {
+        return $this->readLittleEndian($index, 8);
+    }
+
+    /**
+     * @param $index
+     * @return mixed
+     */
+    public function getFloat($index)
+    {
+        $i = $this->readLittleEndian($index, 4);
+
+        return self::convertHelper(self::__FLOAT, $i);
+    }
+
+    /**
+     * @param $index
+     * @return float
+     */
+    public function getDouble($index)
+    {
+        $i = $this->readLittleEndian($index, 4);
+        $i2 = $this->readLittleEndian($index + 4, 4);
+
+        return self::convertHelper(self::__DOUBLE, $i, $i2);
+    }
+
+    const __SHORT = 1;
+    const __INT = 2;
+    const __LONG = 3;
+    const __FLOAT = 4;
+    const __DOUBLE = 5;
+    private static function convertHelper($type, $value, $value2 = null) {
+        // readLittleEndian construct unsigned integer value from bytes. we have to encode this value to
+        // correct bytes, and decode as expected types with `unpack` function.
+        // then it returns correct type value.
+        // see also: http://php.net/manual/en/function.pack.php
+
+        switch ($type) {
+            case self::__SHORT:
+                $helper = pack("v", $value);
+                $v = unpack("s", $helper);
+
+                return $v[1];
+                break;
+            case self::__INT:
+                $helper = pack("V", $value);
+                $v = unpack("l", $helper);
+                return $v[1];
+                break;
+            case self::__LONG:
+                $helper = pack("P", $value);
+                $v = unpack("q", $helper);
+                return $v[1];
+                break;
+            case self::__FLOAT:
+                $inthelper = pack("V", $value);
+                $v = unpack("f", $inthelper);
+                return $v[1];
+                break;
+            case self::__DOUBLE:
+                $inthelper = pack("VV", $value, $value2);
+                $v = unpack("d", $inthelper);
+                return $v[1];
+                break;
+            default:
+                throw new \Exception(sprintf("unexpected type %d specified", $type));
+        }
+    }
+
+    private static function validateValue($min, $max, $value, $type, $additional_notes = "") {
+        if(!($min <= $value && $value <= $max)) {
+            throw new \InvalidArgumentException(sprintf("bad number %s for type %s.%s", $value, $type, $additional_notes));
+        }
+    }
+}
diff --git a/php/Constants.php b/php/Constants.php
new file mode 100644
index 00000000..ef3730d4
--- /dev/null
+++ b/php/Constants.php
@@ -0,0 +1,25 @@
+<?php
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Google\FlatBuffers;
+
+class Constants
+{
+    const SIZEOF_SHORT = 2;
+    const SIZEOF_INT = 4;
+    const FILE_IDENTIFIER_LENGTH = 4;
+}
diff --git a/php/FlatbufferBuilder.php b/php/FlatbufferBuilder.php
new file mode 100644
index 00000000..b72a6d65
--- /dev/null
+++ b/php/FlatbufferBuilder.php
@@ -0,0 +1,918 @@
+<?php
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Google\FlatBuffers;
+
+class FlatbufferBuilder
+{
+    /**
+     * @var ByteBuffer $bb
+     */
+    public $bb;
+
+    /**
+     * @var int $space
+     */
+    protected $space;
+
+    /**
+     * @var int $minalign
+     */
+    protected $minalign = 1;
+
+    /**
+     * @var array $vtable
+     */
+    protected $vtable;
+
+    /**
+     * @var int $vtable_in_use
+     */
+    protected $vtable_in_use = 0;
+
+    /**
+     * @var bool $nested
+     */
+    protected $nested = false;
+
+    /**
+     * @var int $object_start
+     */
+    protected $object_start;
+
+    /**
+     * @var array $vtables
+     */
+    protected $vtables = array();
+
+    /**
+     * @var int $num_vtables
+     */
+    protected $num_vtables = 0;
+
+    /**
+     * @var int $vector_num_elems
+     */
+    protected $vector_num_elems = 0;
+
+    /**
+     * @var bool $force_defaults
+     */
+    protected $force_defaults = false;
+
+    /**
+     * create flatbuffers builder
+     *
+     * @param $initial_size initial byte buffer size.
+     */
+    public function __construct($initial_size)
+    {
+        if ($initial_size <= 0) {
+            $initial_size = 1;
+        }
+        $this->space = $initial_size;
+        $this->bb = $this->newByteBuffer($initial_size);
+    }
+
+    /**
+     * create new bytebuffer
+     *
+     * @param $size
+     * @return ByteBuffer
+     */
+    private function newByteBuffer($size)
+    {
+        return new ByteBuffer($size);
+    }
+
+    /**
+     * returns current bytebuffer offset
+     *
+     * @return int
+     */
+    public function offset()
+    {
+        return $this->bb->capacity() - $this->space;
+    }
+
+    /**
+     * padding buffer
+     *
+     * @param $byte_size
+     */
+    public function pad($byte_size)
+    {
+        for ($i = 0; $i < $byte_size; $i++) {
+            $this->bb->putByte(--$this->space, "\0");
+        }
+    }
+
+    /**
+     * prepare bytebuffer
+     *
+     * @param $size
+     * @param $additional_bytes
+     * @throws \Exception
+     */
+    public function prep($size, $additional_bytes)
+    {
+        if ($size > $this->minalign) {
+            $this->minalign = $size;
+        }
+
+        $align_size = ((~($this->bb->capacity() - $this->space + $additional_bytes)) + 1) & ($size - 1);
+        while ($this->space < $align_size + $size  + $additional_bytes) {
+            $old_buf_size = $this->bb->capacity();
+            $this->bb = $this->growByteBuffer($this->bb);
+            $this->space += $this->bb->capacity() - $old_buf_size;
+        }
+
+        $this->pad($align_size);
+    }
+
+    /**
+     * @param ByteBuffer $bb
+     * @return ByteBuffer
+     * @throws \Exception
+     */
+    private static function growByteBuffer(ByteBuffer $bb)
+    {
+        $old_buf_size = $bb->capacity();
+        if (($old_buf_size & 0xC0000000) != 0) {
+            throw new \Exception("FlatBuffers: cannot grow buffer beyond 2 gigabytes");
+        }
+        $new_buf_size = $old_buf_size << 1;
+
+        $bb->setPosition(0);
+        $nbb = new ByteBuffer($new_buf_size);
+
+        $nbb->setPosition($new_buf_size - $old_buf_size);
+
+        // TODO(chobie): is this little bit faster?
+        //$nbb->_buffer = substr_replace($nbb->_buffer, $bb->_buffer, $new_buf_size - $old_buf_size, strlen($bb->_buffer));
+        for ($i = $new_buf_size - $old_buf_size, $j = 0; $j < strlen($bb->_buffer); $i++, $j++) {
+            $nbb->_buffer[$i] = $bb->_buffer[$j];
+        }
+
+        return $nbb;
+    }
+
+    /**
+     * @param $x
+     */
+    public function putBool($x)
+    {
+        $this->bb->put($this->space -= 1, chr((int)(bool)($x)));
+    }
+
+    /**
+     * @param $x
+     */
+    public function putByte($x)
+    {
+        $this->bb->put($this->space -= 1, chr($x));
+    }
+
+    /**
+     * @param $x
+     */
+    public function putSbyte($x)
+    {
+        $this->bb->put($this->space -= 1, chr($x));
+    }
+
+    /**
+     * @param $x
+     */
+    public function putShort($x)
+    {
+        $this->bb->putShort($this->space -= 2, $x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function putUshort($x)
+    {
+        $this->bb->putUshort($this->space -= 2, $x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function putInt($x)
+    {
+        $this->bb->putInt($this->space -= 4, $x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function putUint($x)
+    {
+        if ($x > PHP_INT_MAX) {
+            throw new \InvalidArgumentException("your platform can't handling uint correctly. use 64bit machine.");
+        }
+
+        $this->bb->putUint($this->space -= 4, $x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function putLong($x)
+    {
+        if ($x > PHP_INT_MAX) {
+            throw new \InvalidArgumentException("your platform can't handling long correctly. use 64bit machine.");
+        }
+
+        $this->bb->putLong($this->space -= 8, $x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function putUlong($x)
+    {
+        if ($x > PHP_INT_MAX) {
+            throw new \InvalidArgumentException("your platform can't handling ulong correctly. this is php limitations. please wait extension release.");
+        }
+
+        $this->bb->putUlong($this->space -= 8, $x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function putFloat($x)
+    {
+        $this->bb->putFloat($this->space -= 4, $x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function putDouble($x)
+    {
+        $this->bb->putDouble($this->space -= 8, $x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function addBool($x)
+    {
+        $this->prep(1, 0);
+        $this->putBool($x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function addByte($x)
+    {
+        $this->prep(1, 0);
+        $this->putByte($x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function addSbyte($x)
+    {
+        $this->prep(1, 0);
+        $this->putSbyte($x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function addShort($x)
+    {
+        $this->prep(2, 0);
+        $this->putShort($x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function addUshort($x)
+    {
+        $this->prep(2, 0);
+        $this->putUshort($x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function addInt($x)
+    {
+        $this->prep(4, 0);
+        $this->putInt($x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function addUint($x)
+    {
+        $this->prep(4, 0);
+        $this->putUint($x);
+    }
+
+
+    /**
+     * @param $x
+     */
+    public function addLong($x)
+    {
+        $this->prep(8, 0);
+        $this->putLong($x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function addUlong($x)
+    {
+        $this->prep(8, 0);
+        $this->putUlong($x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function addFloat($x)
+    {
+        $this->prep(4, 0);
+        $this->putFloat($x);
+    }
+
+    /**
+     * @param $x
+     */
+    public function addDouble($x)
+    {
+        $this->prep(8, 0);
+        $this->putDouble($x);
+    }
+
+    /**
+     * @param $o
+     * @param $x
+     * @param $d
+     */
+    public function addBoolX($o, $x, $d)
+    {
+        if ($this->force_defaults || $x != $d) {
+            $this->addBool($x);
+            $this->slot($o);
+        }
+    }
+
+    /**
+     * @param $o
+     * @param $x
+     * @param $d
+     */
+    public function addByteX($o, $x, $d)
+    {
+        if ($this->force_defaults || $x != $d) {
+            $this->addByte($x);
+            $this->slot($o);
+        }
+    }
+
+    /**
+     * @param $o
+     * @param $x
+     * @param $d
+     */
+    public function addSbyteX($o, $x, $d)
+    {
+        if ($this->force_defaults || $x != $d) {
+            $this->addSbyte($x);
+            $this->slot($o);
+        }
+    }
+
+    /**
+     * @param $o
+     * @param $x
+     * @param $d
+     */
+    public function addShortX($o, $x, $d)
+    {
+        if ($this->force_defaults || $x != $d) {
+            $this->addShort($x);
+            $this->slot($o);
+        }
+    }
+
+    /**
+     * @param $o
+     * @param $x
+     * @param $d
+     */
+    public function addUshortX($o, $x, $d)
+    {
+        if ($this->force_defaults || $x != $d) {
+            $this->addUshort($x);
+            $this->slot($o);
+        }
+    }
+
+    /**
+     * @param $o
+     * @param $x
+     * @param $d
+     */
+    public function addIntX($o, $x, $d)
+    {
+        if ($this->force_defaults || $x != $d) {
+            $this->addInt($x);
+            $this->slot($o);
+        }
+    }
+
+    /**
+     * @param $o
+     * @param $x
+     * @param $d
+     */
+    public function addUintX($o, $x, $d)
+    {
+        if ($this->force_defaults || $x != $d) {
+            $this->addUint($x);
+            $this->slot($o);
+        }
+    }
+
+    /**
+     * @param $o
+     * @param $x
+     * @param $d
+     */
+    public function addLongX($o, $x, $d)
+    {
+        if ($this->force_defaults || $x != $d) {
+            $this->addLong($x);
+            $this->slot($o);
+        }
+    }
+
+    /**
+     * @param $o
+     * @param $x
+     * @param $d
+     */
+    public function addUlongX($o, $x, $d)
+    {
+        if ($this->force_defaults || $x != $d) {
+            $this->addUlong($x);
+            $this->slot($o);
+        }
+    }
+
+
+    /**
+     * @param $o
+     * @param $x
+     * @param $d
+     */
+    public function addFloatX($o, $x, $d)
+    {
+        if ($this->force_defaults || $x != $d) {
+            $this->addFloat($x);
+            $this->slot($o);
+        }
+    }
+
+    /**
+     * @param $o
+     * @param $x
+     * @param $d
+     */
+    public function addDoubleX($o, $x, $d)
+    {
+        if ($this->force_defaults || $x != $d) {
+            $this->addDouble($x);
+            $this->slot($o);
+        }
+    }
+
+    /**
+     * @param $o
+     * @param $x
+     * @param $d
+     * @throws \Exception
+     */
+    public function addOffsetX($o, $x, $d)
+    {
+        if ($this->force_defaults || $x != $d) {
+            $this->addOffset($x);
+            $this->slot($o);
+        }
+    }
+
+    /**
+     * @param $off
+     * @throws \Exception
+     */
+    public function addOffset($off)
+    {
+        $this->prep(Constants::SIZEOF_INT, 0); // Ensure alignment is already done
+        if ($off > $this->offset()) {
+            throw new \Exception("");
+        }
+
+        $off = $this->offset() - $off + Constants::SIZEOF_INT;
+        $this->putInt($off);
+    }
+
+    /**
+     * @param $elem_size
+     * @param $num_elems
+     * @param $alignment
+     * @throws \Exception
+     */
+    public function startVector($elem_size, $num_elems, $alignment)
+    {
+        $this->notNested();
+        $this->vector_num_elems = $num_elems;
+        $this->prep(Constants::SIZEOF_INT, $elem_size * $num_elems);
+        $this->prep($alignment, $elem_size * $num_elems); // Just in case alignemnt > int;
+    }
+
+    /**
+     * @return int
+     */
+    public function endVector()
+    {
+        $this->putUint($this->vector_num_elems);
+        return $this->offset();
+    }
+
+    protected function is_utf8($bytes)
+    {
+        $len = strlen($bytes);
+        if ($len < 1) {
+            /* NOTE: always return 1 when passed string is null */
+            return true;
+        }
+
+        for ($j = 0, $i = 0; $i < $len; $i++) {
+            // check ACII
+            if ($bytes[$j] == "\x09" ||
+                $bytes[$j] == "\x0A" ||
+                $bytes[$j] == "\x0D" ||
+                ($bytes[$j] >= "\x20" && $bytes[$j] <= "\x7E")) {
+                $j++;
+                continue;
+            }
+
+            /* non-overlong 2-byte */
+            if ((($i+1) <= $len) &&
+                ($bytes[$j] >= "\xC2" && $bytes[$j] <= "\xDF" &&
+                    ($bytes[$j+1] >= "\x80" && $bytes[$j+1] <= "\xBF"))) {
+                $j += 2;
+                $i++;
+                continue;
+            }
+
+            /* excluding overlongs */
+            if ((($i + 2) <= $len) &&
+                $bytes[$j] == "\xE0" &&
+                ($bytes[$j+1] >= "\xA0" && $bytes[$j+1] <= "\xBF" &&
+                    ($bytes[$j+2] >= "\x80" && $bytes[$j+2] <= "\xBF"))) {
+                $bytes += 3;
+                $i +=2;
+                continue;
+            }
+
+            /* straight 3-byte */
+            if ((($i+2) <= $len) &&
+                (($bytes[$j] >= "\xE1" && $bytes[$j] <= "\xEC") ||
+                    $bytes[$j] == "\xEE" ||
+                    $bytes[$j] = "\xEF") &&
+                ($bytes[$j+1] >= "\x80" && $bytes[$j+1] <= "\xBF") &&
+                ($bytes[$j+2] >= "\x80" && $bytes[$j+2] <= "\xBF")) {
+                $j += 3;
+                $i += 2;
+                continue;
+            }
+
+            /* excluding surrogates */
+            if ((($i+2) <= $len) &&
+                $bytes[$j] == "\xED" &&
+                ($bytes[$j+1] >= "\x80" && $bytes[$j+1] <= "\x9f" &&
+                    ($bytes[$j+2] >= "\x80" && $bytes[$j+2] <= "\xBF"))) {
+                $j += 3;
+                $i += 2;
+                continue;
+            }
+
+            /* planes 1-3 */
+            if ((($i + 3) <= $len) &&
+                $bytes[$j] == "\xF0" &&
+                ($bytes[$j+1] >= "\x90" && $bytes[$j+1] <= "\xBF") &&
+                ($bytes[$j+2] >= "\x80" && $bytes[$j+2] <= "\xBF") &&
+                ($bytes[$j+3] >= "\x80" && $bytes[$j+3] <= "\xBF")) {
+                $j += 4;
+                $i += 3;
+                continue;
+            }
+
+
+            /* planes 4-15 */
+            if ((($i+3) <= $len) &&
+                $bytes[$j] >= "\xF1" && $bytes[$j] <= "\xF3" &&
+                $bytes[$j+1] >= "\x80" && $bytes[$j+1] <= "\xBF" &&
+                $bytes[$j+2] >= "\x80" && $bytes[$j+2] <= "\xBF" &&
+                $bytes[$j+3] >= "\x80" && $bytes[$j+3] <= "\xBF"
+            ) {
+                $j += 4;
+                $i += 3;
+                continue;
+            }
+
+            /* plane 16 */
+            if ((($i+3) <= $len) &&
+                $bytes[$j] == "\xF4" &&
+                ($bytes[$j+1] >= "\x80" && $bytes[$j+1] <= "\x8F") &&
+                ($bytes[$j+2] >= "\x80" && $bytes[$j+2] <= "\xBF") &&
+                ($bytes[$j+3] >= "\x80" && $bytes[$j+3] <= "\xBF")
+            ) {
+                $bytes += 4;
+                $i += 3;
+                continue;
+            }
+
+
+            return false;
+        }
+
+        return true;
+    }
+
+
+    /**
+     * @param $s
+     * @return int
+     * @throws \Exception
+     */
+    public function createString($s)
+    {
+        if (!$this->is_utf8($s)) {
+            throw new \InvalidArgumentException("string must be utf-8 encoded value.");
+        }
+
+        $this->notNested();
+        $this->addByte(0); // null terminated
+        $this->startVector(1, strlen($s), 1);
+        $this->space -= strlen($s);
+        for ($i =  $this->space, $j = 0 ; $j < strlen($s) ; $i++, $j++) {
+            $this->bb->_buffer[$i] = $s[$j];
+        }
+        return $this->endVector();
+    }
+
+    /**
+     * @throws \Exception
+     */
+    public function notNested()
+    {
+        if ($this->nested) {
+            throw new \Exception("FlatBuffers; object serialization must not be nested");
+        }
+    }
+
+    /**
+     * @param $obj
+     * @throws \Exception
+     */
+    public function nested($obj)
+    {
+        if ($obj != $this->offset()) {
+            throw new \Exception("FlatBuffers: struct must be serialized inline");
+        }
+    }
+
+    /**
+     * @param $numfields
+     * @throws \Exception
+     */
+    public function startObject($numfields)
+    {
+        $this->notNested();
+        if ($this->vtable == null || count($this->vtable) < $numfields) {
+            $this->vtable = array();
+        }
+
+        $this->vtable_in_use = $numfields;
+        for ($i = 0; $i < $numfields; $i++) {
+            $this->vtable[$i] = 0;
+        }
+
+        $this->nested = true;
+        $this->object_start = $this->offset();
+    }
+
+    /**
+     * @param $voffset
+     * @param $x
+     * @param $d
+     * @throws \Exception
+     */
+    public function addStructX($voffset, $x, $d)
+    {
+        if ($x != $d) {
+            $this->nested($x);
+            $this->slot($voffset);
+        }
+    }
+
+    /**
+     * @param $voffset
+     * @param $x
+     * @param $d
+     * @throws \Exception
+     */
+    public function addStruct($voffset, $x, $d)
+    {
+        if ($x != $d) {
+            $this->nested($x);
+            $this->slot($voffset);
+        }
+    }
+
+    /**
+     * @param $voffset
+     */
+    public function slot($voffset)
+    {
+        $this->vtable[$voffset] = $this->offset();
+    }
+
+    /**
+     * @return int
+     * @throws \Exception
+     */
+    public function endObject()
+    {
+        if ($this->vtable == null || !$this->nested) {
+            throw new \Exception("FlatBuffers: endObject called without startObject");
+        }
+
+        $this->addInt(0);
+        $vtableloc = $this->offset();
+
+        for ($i = $this->vtable_in_use -1; $i >= 0; $i--) {
+            $off = ($this->vtable[$i] != 0) ? $vtableloc - $this->vtable[$i] : 0;
+            $this->addShort($off);
+        }
+
+        $standard_fields = 2; // the fields below
+        $this->addShort($vtableloc - $this->object_start);
+        $this->addShort(($this->vtable_in_use + $standard_fields) * Constants::SIZEOF_SHORT);
+
+        // search for an existing vtable that matches the current one.
+        $existing_vtable = 0;
+
+        for ($i = 0; $i < $this->num_vtables; $i++) {
+            $vt1 = $this->bb->capacity() - $this->vtables[$i];
+            $vt2 = $this->space;
+
+            $len = $this->bb->getShort($vt1);
+
+            if ($len == $this->bb->getShort($vt2)) {
+                for ($j = Constants::SIZEOF_SHORT; $j < $len; $j += Constants::SIZEOF_SHORT) {
+                    if ($this->bb->getShort($vt1 + $j) != $this->bb->getShort($vt2 + $j)) {
+                        continue 2;
+                    }
+                }
+                $existing_vtable = $this->vtables[$i];
+                break;
+            }
+        }
+
+        if ($existing_vtable != 0) {
+            // Found a match:
+            // Remove the current vtable
+            $this->space = $this->bb->capacity() - $vtableloc;
+            $this->bb->putInt($this->space, $existing_vtable - $vtableloc);
+        } else {
+            // No Match:
+            // Add the location of the current vtable to the list of vtables
+            if ($this->num_vtables == count($this->vtables)) {
+                $vtables = $this->vtables;
+                $this->vtables = array();
+                // copy of
+                for ($i = 0; $i < count($vtables) * 2; $i++) {
+                    $this->vtables[$i] = ($i < count($vtables)) ? $vtables[$i] : 0;
+                }
+            }
+            $this->vtables[$this->num_vtables++] = $this->offset();
+            $this->bb->putInt($this->bb->capacity() - $vtableloc, $this->offset() - $vtableloc);
+        }
+
+        $this->nested = false;
+        $this->vtable = null;
+        return $vtableloc;
+    }
+
+    /**
+     * @param $table
+     * @param $field
+     * @throws \Exception
+     */
+    public function required($table, $field)
+    {
+        $table_start = $this->bb->capacity() - $table;
+        $vtable_start = $table_start - $this->bb->getInt($table_start);
+        $ok = $this->bb->getShort($vtable_start + $field) != 0;
+
+        if (!$ok) {
+            throw new \Exception("FlatBuffers: field "  . $field  .  " must be set");
+        }
+    }
+
+    /**
+     * @param $root_table
+     * @throws \Exception
+     */
+    public function finish($root_table, $identifier = null)
+    {
+        if ($identifier == null) {
+            $this->prep($this->minalign, Constants::SIZEOF_INT);
+            $this->addOffset($root_table);
+            $this->bb->setPosition($this->space);
+        } else {
+            $this->prep($this->minalign, Constants::SIZEOF_INT + Constants::FILE_IDENTIFIER_LENGTH);
+            if (strlen($identifier) != Constants::FILE_IDENTIFIER_LENGTH) {
+                throw new \InvalidArgumentException(
+                    sprintf("FlatBuffers: file identifier must be length %d",
+                        Constants::FILE_IDENTIFIER_LENGTH));
+            }
+
+            for ($i = Constants::FILE_IDENTIFIER_LENGTH - 1; $i >= 0;
+                  $i--) {
+                $this->addByte(ord($identifier[$i]));
+            }
+            $this->finish($root_table);
+        }
+    }
+
+    /**
+     * @param bool $forceDefaults
+     */
+    public function forceDefaults($forceDefaults)
+    {
+        $this->force_defaults = $forceDefaults;
+    }
+
+    /**
+     * @return ByteBuffer
+     */
+    public function dataBuffer()
+    {
+        return $this->bb;
+    }
+
+    /**
+     * @return int
+     */
+    public function dataStart()
+    {
+        return $this->space;
+    }
+
+    /**
+     * @return string
+     */
+    public function sizedByteArray()
+    {
+        $start = $this->space;
+        $length = $this->bb->capacity() - $this->space;
+
+        $result = str_repeat("\0", $length);
+        $this->bb->setPosition($start);
+        $this->bb->getX($result);
+
+        return $result;
+    }
+}
diff --git a/php/Struct.php b/php/Struct.php
new file mode 100644
index 00000000..94e712b2
--- /dev/null
+++ b/php/Struct.php
@@ -0,0 +1,31 @@
+<?php
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Google\FlatBuffers;
+
+abstract class Struct
+{
+    /**
+     * @var int $bb_pos
+     */
+    protected $bb_pos;
+
+    /**
+     * @var ByteBuffer $bb
+     */
+    protected $bb;
+}
diff --git a/php/Table.php b/php/Table.php
new file mode 100644
index 00000000..7f611456
--- /dev/null
+++ b/php/Table.php
@@ -0,0 +1,129 @@
+<?php
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Google\FlatBuffers;
+
+abstract class Table
+{
+    /**
+     * @var int $bb_pos
+     */
+    protected $bb_pos;
+    /**
+     * @var ByteBuffer $bb
+     */
+    protected $bb;
+
+    public function __construct()
+    {
+    }
+
+    /**
+     * returns actual vtable offset
+     *
+     * @param $vtable_offset
+     * @return int offset > 0 means exist value. 0 means not exist
+     */
+    protected function __offset($vtable_offset)
+    {
+        $vtable = $this->bb_pos - $this->bb->getInt($this->bb_pos);
+        return $vtable_offset < $this->bb->getShort($vtable) ? $this->bb->getShort($vtable + $vtable_offset) : 0;
+    }
+
+    /**
+     * @param $offset
+     * @return mixed
+     */
+    protected function __indirect($offset)
+    {
+        return $offset + $this->bb->getInt($offset);
+    }
+
+    /**
+     * fetch utf8 encoded string.
+     *
+     * @param $offset
+     * @return string
+     */
+    protected function __string($offset)
+    {
+        $offset += $this->bb->getInt($offset);
+        $len = $this->bb->getInt($offset);
+        $startPos = $offset + Constants::SIZEOF_INT;
+        return substr($this->bb->_buffer, $startPos, $len);
+    }
+
+    /**
+     * @param $offset
+     * @return int
+     */
+    protected function __vector_len($offset)
+    {
+        $offset += $this->bb_pos;
+        $offset += $this->bb->getInt($offset);
+        return $this->bb->getInt($offset);
+    }
+
+    /**
+     * @param $offset
+     * @return int
+     */
+    protected function __vector($offset)
+    {
+        $offset += $this->bb_pos;
+        // data starts after the length
+        return $offset + $this->bb->getInt($offset) + Constants::SIZEOF_INT;
+    }
+
+//    protected function __vector_as_bytebuffer($vector_offset, $elem_size)
+//    {
+//    }
+
+    /**
+     * @param Table $table
+     * @param int $offset
+     * @return Table
+     */
+    protected function __union($table, $offset)
+    {
+        $offset += $this->bb_pos;
+        $table->bb_pos = $offset + $this->bb->getInt($offset);
+        $table->bb = $this->bb;
+        return $table;
+    }
+
+    /**
+     * @param ByteBuffer $bb
+     * @param string $ident
+     * @return bool
+     * @throws \ArgumentException
+     */
+    protected static function __has_identifier($bb, $ident)
+    {
+        if (strlen($ident) != Constants::FILE_IDENTIFIER_LENGTH) {
+            throw new \ArgumentException("FlatBuffers: file identifier must be length "  . Constants::FILE_IDENTIFIER_LENGTH);
+        }
+
+        for ($i = 0; $i < 4; $i++) {
+            if ($ident[$i] != $bb->get($bb->getPosition() + Constants::SIZEOF_INT + $i)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+}