Finding used functions from php source file

Basically I want to find a function from a php string source content. I'm trying to parse a php file and read its content into string. I want to find something like:

function_name(paras) or function_name() or function_name(params, params)

for example if source contains:

echo 'Greetings'.greet("I'm Johan");
$age = date_of_birth(date());
echo 'I am ' .$age . 'years old';

it would then find greet, date_of_birth, date because these are the functions used.

If you want to get the parameters including nested brackets, like your date_of_birth(date()), its maybe not impossible with regex but very difficult.

If you say its enough to find the name of the function then you can try this:

\w+(?=\()

See it here on Regexr

That will match at least one word character that is followed by an opening bracket.

\w contains letters, digits and the underscore

(?=\() is a positive look ahead that checks if a ( is following

you need a regular expression: maybe something like this

preg_match("[a-zA-Z_][a-zA-Z_0-9]*(.*)",$stringToLookIn);

preg_match_all('/([a-zA-Z_]\w+)\s*\(/', $source, $match);
var_dump($match[1]);