PHP 7.0.6 Released

    The SeekableIterator interface

    (PHP 5 >= 5.1.0, PHP 7)

    Introduction

    The Seekable iterator.

    Interface synopsis

    SeekableIterator extends Iterator {
    /* Methods */
    abstract public void seek ( int $position )
    /* Inherited methods */
    abstract public mixed Iterator::current ( void )
    abstract public scalar Iterator::key ( void )
    abstract public void Iterator::next ( void )
    abstract public void Iterator::rewind ( void )
    abstract public boolean Iterator::valid ( void )
    }

    Example #1 Basic usage

    This example demonstrates creating a custom SeekableIterator, seeking to a position and handling an invalid position.

    <?php
    class MySeekableIterator implements SeekableIterator {

        private     $position;

        private     $array = array(
                "first element",
                "second element",
                "third element",
                "fourth element"
            );

            /* Method required for SeekableIterator interface */

            public function seek($position) {
          if (!isset(    $this->array[$position])) {
              throw new     OutOfBoundsException("invalid seek position ($position)");
          }

              $this->position = $position;
        }

            /* Methods required for Iterator interface */
        
            public function rewind() {
                $this->position = 0;
        }

        public function     current() {
            return     $this->array[$this->position];
        }

        public function     key() {
            return     $this->position;
        }

        public function     next() {
            ++    $this->position;
        }

        public function     valid() {
            return isset(    $this->array[$this->position]);
        }
    }

    try {

            $it = new MySeekableIterator;
        echo     $it->current(), "\n";
        
            $it->seek(2);
        echo     $it->current(), "\n";
        
            $it->seek(1);
        echo     $it->current(), "\n";
        
            $it->seek(10);
        
    } catch (    OutOfBoundsException $e) {
        echo     $e->getMessage();
    }
    ?>

    The above example will output something similar to:

    first element
third element
second element
invalid seek position (10)

    Table of Contents

    User Contributed Notes

    svenr at selfhtml dot org
    4 years ago
    Best method:

    <?php

    if ($object instanceof SeekableIterator) {
      echo     "\$object has method seek()";
    }

    ?>

    Please, make use of checking if a particular interface has been implemented to assure that the object you are dealing with definately has the methods you are about to use.

    This also works as typehinting:

    <?php

    class foo {
      public function     doSomeSeeking(SeekableIterator $seekMe) {
            $seekMe->seek(10); // will work, otherwise Typehint triggers complaints
          }
    }

    ?>
    Anonymous
    2 years ago
    The code above is missing a closing parenthesis.

    <?php
    if (!isset($this->array[$position]) {
              throw new     OutOfBoundsException("invalid seek position ($position)");
    }
    ?>

    should be

    <?php
    if (!isset($this->array[$position])) { // close here
                  throw new OutOfBoundsException("invalid seek position ($position)");
    }
    ?>
    martin at smasty dot net
    4 years ago
    The reflection approach:

    <?php

    $reflection     = new ReflectionClass('MySeekableIterator');
    if(    $reflection->hasMethod('seek'))
      echo     "This class has method seek().";

    ?>
    marcin dot kleczek at gmail dot com
    6 years ago
    Better method:

    <?php
                $class     = 'SeekableIterator';
                    $findingMethod = 'seek'; // have to be lower chars
              
                    $methods = get_class_methods($class);
              
                foreach(     $methods as $pVal )
                    if (     $findingMethod == strtolower($pVal) ) {
                        echo     'This class has method seek().';
                        break;
                    }

    }

    ?>

    Best method: http://php.net/manual/en/function.method-exists.php
    dreake at example dot com
    6 years ago
    This example show how to check if some class has method seek() (or another method).

    <?php
    $class     = 'SeekableIterator';
                    $findingMethod = 'seek'; // have to be lower chars
               
                    $methods = get_class_methods($class);
               
                for(    $i = 0, $ii = count($methods); $i < $ii; $i++){
                        $sl = strtolower($methods[$i]);
                        $lowermethods[$i] = $sl;
                }
               
               
                if(    in_array($findingMethod,$lowermethods))
                    echo     'This class has method seek().';
    ?>
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