TestArrayWalk.php

<?php
    /**
     * TestArrayWalk
     *
     * This is the code I have used when describing an issue I had with array_walk, closures and referencing $this
     * within PHP version 5.3.3.
     *
     * The original stackoverflow question can be seen here:
     * http://stackoverflow.com/questions/19033184/using-this-when-not-in-object-context-error-within-array-walk
     *
     * The TestArrayWalk class will not work in 5.3.3 while the TestForEach class will. They both do exactly the
     * same thing, just using slightly different code.
     */
    Class TestArrayWalk
    {
        /** @var null|array */
        protected $userInput = null;

        /**
         * This expects to be passed an array of the users input from
         * the input fields.
         *
         * @param  array $input
         * @return void
         */
        public function setUserInput( array $input )
        {
            $this->userInput = $input;

            // Lets explode the users input and format it in a way that this class
            // will use for marking

            array_walk( $this->userInput, function( &$rawValue )
                {
                    $rawValue = array(
                        'raw' => $rawValue,
                        'words' => $this->splitIntoKeywordArray( $rawValue ),
                        'marked' => false,
                        'matched' => array()
                    );
                }
            );
        }

        public function getUserInput()
        {
            return $this->userInput;
        }

        protected function splitIntoKeywordArray( $input )
        {
            if ( ! is_string( $input )){ return array(); }
            return preg_split('/(\s|[\.,\/:;!?])/', $input, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
        }

    }

    Class TestForEach
    {
        /** @var null|array */
        protected $userInput = null;

        /**
         * This expects to be passed an array of the users input from
         * the input fields.
         *
         * @param  array $input
         * @return void
         */
        public function setUserInput( array $input )
        {
            $this->userInput = $input;

            // Lets explode the users input and format it in a way that this class
            // will use for marking

            foreach( $this->userInput as &$rawValue )
            {
                $rawValue = array(
                    'raw' => $rawValue,
                    'words' => $this->splitIntoKeywordArray( $rawValue ),
                    'marked' => false,
                    'matched' => array()
                );
            }
            unset($rawValue); // Clean up pointer
        }

        public function getUserInput()
        {
            return $this->userInput;
        }

        protected function splitIntoKeywordArray( $input )
        {
            if ( ! is_string( $input )){ return array(); }
            return preg_split('/(\s|[\.,\/:;!?])/', $input, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
        }

    }

    $testArrayWalk = new TestArrayWalk();
    $testArrayWalk->setUserInput(
            array(
                'This is a test input',
                'This is another test input'
                )
        );

    var_dump( $testArrayWalk->getUserInput() );

    $testForeach = new TestForEach();
    $testForeach->setUserInput(
            array(
                'This is a test input',
                'This is another test input'
                )
        );

    var_dump( $testForeach->getUserInput() );