This script analyzes PHP source code to determine which extensions are required for a project. It uses tokenizer to parse the source code and Reflection to figure out which extensions provide functions and classes.

• Checks functions and classes
• Recursively walks directory trees
• Identifies builtin extensions:
  • You typically do not need to list these in the require section of a composer.json
  • Note: a builtin extension means the extension is required in any PHP build (i.e. always going to be built-in). You may have other extensions that are built into your specific version of PHP that are optional; these optional, built-in extensions are not identified.

usage: depends.php [options] <file-or-directory> [file-or-directory...]

Options:
  --suffix=<suffix1[,suffix2,...]>     Only processes files having suffix(es)

$ php depends.php --suffix .php ~/code/open-source/drupal/core
Core (builtin)
ctype
curl
date (builtin)
filter
gd
hash (builtin)
iconv
json (builtin)
libxml
mbstring
pcre (builtin)
Reflection (builtin)
session
SimpleXML
SPL (builtin)
standard (builtin)
xml
zlib

You should run this utility using the minimum PHP supported by your project. The list of built-in extensions is modified based on PHP version since some non-built-in extensions were updated to built-in extensions in later versions of PHP.

The script does not check global constants at this time. If a project uses constants defined by an extension and nothing else from the extension (i.e. functions or classes), then the extension will not be detected. Note that this limitation does not apply to class constants; class constants don't need to be handled specifically since the extension will be detected via the class component of a class constant expression (e.g. PDO::FETCH_ASSOC captures class PDO).

The script cannot detect an extension if its usage is limited to functions/classes denoted via string literals. For example, if you only use the ctype extension via a string reference to one of its functions (e.g. array_map('ctype_alpha',str_split('name1'))), then the tool will not detect the extension. The same applies to objects instantiated from class names passed as strings.

The script cannot determine if particular extension usage is optional in your application (e.g. via extension_loaded()). Furthermore, since only a regular lexical analysis is performed, the tool cannot follow code paths and test for optional usage.