PHP Regex Question - php

Question

Would it be possible to make a regex that reads {variable} like <?php echo $variable ?> in PHP files?
Thanks
Remy

Answer 1

The PHP manual already provides a regular expression for variable names:
[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*
You just have to alter it to this:
\{[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*\}
And you’re done.
Edit   You should be aware that a simple sequential replacment of such occurrences as Ross proposed can cause some unwanted behavior when for example a substitution also contains such variables.
So you should better parse the code and replace those variables separately. An example:
$tokens = preg_split('/(\{[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*\})/', $string, -1, PREG_SPLIT_DELIM_CAPTURE);
for ($i=1, $n=count($tokens); $i<$n; $i+=2) {
$name = substr($tokens[$i], 1, -1);
if (isset($variables[$name])) {
$tokens[$i] = $variables[$name];
} else {
// Error: variable missing
}
}
$string = implode('', $tokens);

Answer 2

It sounds like you're trying to do some template variable replacement ;)
I'd advise collecting your variables first, in an array for example, and then use something like:
// Variables are stored in $vars which is an array
foreach ($vars as $name => $value) {
$str = str_replace('{' . $name . '}', $value, $str);
}

Answer 3

{Not actually an answer, but need clarification}
Could you expand your question? Are you wanting to apply a regex to the contents of $variable?

Answer 4

The following line should replace all occurences of the string '{variable}' with the value of the global variable $variable:
$mystring = preg_replace_callback(
'/\{([a-zA-Z][\w\d]+)\}/',
create_function('$matches', 'return $GLOBALS[$matches[1]];'),
$mystring);
Edit: Replace the regex used here by the one mentioned by Gumbo to precisely catch all possible PHP variable names.

Answer 5

(in comments) i want to be able to type {variable}
instead of <?php echo $variable ?>
Primitive approach: You could use an external program (e.g. a Python script) to preprocess your files, making the following regex substitution:
"{([a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*)}"
with
"<?php echo $\g<1> ?>"
Better approach: Write a macro in your IDE or code editor to automatically make the substitution for you.