Help

[jamiecarter]

Guys,  total PHP noob here but years of MS development experience (I know, I know,,,).

 

Really need to get an understanding of this code, I have a handle on the individual lines and can run the code, but overall I'm kinda at a loss, all help much appreciated!

 

class MyTestClass

{

const REGEXP = '/\{(((?>[^\{\}]+)|(?R))*)\}/x';

 

public function render($text)

{

               return preg_replace_callback(

self::REGEXP,

[$this, 'replace'],

$text

);

}

 

public function replace($text)

{

$text = $this->render($text[1]);

$parts = explode('|', $text);

return trim($parts[array_rand($parts)]);

}

 

}

 

$obj = new MyTestClass();

 

$result = $obj->replace("Fred");

 

echo $result;

 

[scootstah]

What exactly are you struggling with?

[hansford]

That regex is not going to work. Lay out in detail what you expect this class to do.

[Jacques1]

The regex is perfectly fine, but you're not using the class correctly.

 

What this does is look for substrings of the kind {<choice₁>|<choice₂>|<choice₃>|...|<choice_n>} and randomly replace them with one of the substrings <choice₁>, <choice₂>, <choice₃>, ..., <choice_n>. For example,

Have a look at our {fabulous|fantastic|awesome} pet shop.

could become “Have a look at our fantastic pet shop.” or “Have a look at our awesome pet shop”.

 

Nested patterns are also supported:

We sell {furry {cats|kittens}|adorable dogs}.

So it's basically a simple text generator.

You use the class by calling the render() method with an appropriate input. Do not call replace(), that's just an internal method.

<?php

class TextGenerator
{
    const REGEXP = '/\{(((?>[^{}]+)|(?R))*)\}/';

    public function render($text)
    {
        return preg_replace_callback(
            self::REGEXP,
            [$this, 'replace'],
            $text
        );
    }

    public function replace($text)
    {
        $text = $this->render($text[1]);
        $parts = explode('|', $text);
        return trim($parts[array_rand($parts)]);
    }

}

$textGenerator = new TextGenerator();
echo $textGenerator->render('We sell {furry {cats|kittens}|adorable dogs}.');

Edited September 26, 2015 by Jacques1

[jamiecarter]

Jacques1 - thank you very much for the reply - it has really helped.   In the Replace function, the line

$text = $this->render($text[1]);

is confusing me, does this "recall" the Render function??

 

If I had to add a second parameter to Render, how would I pass it into the callback?

 

Thanks

[Jacques1]

In the Replace function, the line

$text = $this->render($text[1]);

is confusing me, does this "recall" the Render function??

 

Yes, the method is called repeatedly to handle nested expressions.

 

 

 

If I had to add a second parameter to Render, how would I pass it into the callback?

 

You can use a closure as the callback function. It has access to variables in the scope of its definition:

<?php

class TextGenerator
{
    const REGEXP = '/\{(((?>[^{}]+)|(?R))*)\}/';

    public function render($text, $separator)
    {
        $replace = function ($subject) use ($separator) {
            $subject = $this->render($subject[1], $separator);
            $parts = explode($separator, $subject);
            return trim($parts[array_rand($parts)]);
        };

        return preg_replace_callback(
            self::REGEXP,
            $replace,
            $text
        );
    }
}

$textGenerator = new TextGenerator();
$separator = '/';
echo $textGenerator->render('We sell {furry {cats/kittens}/adorable dogs}.', $separator);

This is actually a cleaner solution in general, because you don't need a pseudo-public replace() method.

[jamiecarter]

Wow. Great much appreciated!

[jamiecarter]

One final question - promise!

 

Why will the above code not work in PHP 5.3, its fine in 5.4 and above?

 

Thanks

[Jacques1]

PHP 5.3 doesn't support $this in a closure. You need to explicitly import it as a variable:

public function render($text, $separator)
{
    $currentObject = $this;
    $replace = function ($subject) use ($currentObject, $separator) {
        $subject = $currentObject->render($subject[1], $separator);
        ...
    };
}

Note that both PHP 5.3 and PHP 5.4 have reached end-of-life.