silverstripe-framework/core/manifest/ConfigStaticManifest.php

<?php
/**
 * A utility class which builds a manifest of the statics defined in all classes, along with their
 * access levels and values
 *
 * We use this to make the statics that the Config system uses as default values be truely immutable.
 *
 * It has the side effect of allowing Config to avoid private-level access restrictions, so we can
 * optionally catch attempts to modify the config statics (otherwise the modification will appear
 * to work, but won't actually have any effect - the equvilent of failing silently)
 *
 * @subpackage manifest
 */
class SS_ConfigStaticManifest {

	protected $base;
	protected $tests;

	protected $cache;
	protected $key;

	protected $index;
	protected $statics;

	static protected $initial_classes = array(
		'Object', 'ViewableData', 'Injector', 'Director'
	);

	/**
	 * Constructs and initialises a new config static manifest, either loading the data
	 * from the cache or re-scanning for classes.
	 *
	 * @param string $base The manifest base path.
	 * @param bool   $includeTests Include the contents of "tests" directories.
	 * @param bool   $forceRegen Force the manifest to be regenerated.
	 * @param bool   $cache If the manifest is regenerated, cache it.
	 */
	public function __construct($base, $includeTests = false, $forceRegen = false, $cache = true) {
		$this->base  = $base;
		$this->tests = $includeTests;

		$this->cache = SS_Cache::factory('SS_ConfigStatics', 'Core', array(
			'automatic_serialization' => true,
			'lifetime' => null
		));

		$this->key = 'sc_'.sha1($base . ($includeTests ? '!tests' : ''));

		if(!$forceRegen) {
			$this->index = $this->cache->load($this->key);
		}

		if($this->index) {
			$this->statics = $this->index['$statics'];
		}
		else {
			$this->regenerate($cache);
		}
	}

	public function get($class, $name, $default) {
		if (!isset($this->statics[$class])) {
			if (isset($this->index[$class])) {
				$info = $this->index[$class];

				if ($details = $this->cache->load($this->key.'_'.$info['base'])) {
					$this->statics += $details;
				}

				if (!isset($this->statics[$class])) {
					$this->handleFile(null, $info['path'], null);
				}
			}
			else {
				$this->statics[$class] = false;
			}
		}

		if (isset($this->statics[$class][$name])) {
			$static = $this->statics[$class][$name];

			if ($static['access'] != T_PRIVATE) {
				Deprecation::notice('3.1.0', "Config static $class::\$$name must be marked as private", Deprecation::SCOPE_GLOBAL);
				// Don't warn more than once per static
				$static['access'] = T_PRIVATE;
			}

			return $static['value'];
		}

		return $default;
	}

	/**
	 * Completely regenerates the manifest file.
	 */
	public function regenerate($cache = true) {
		$this->statics = array();

		$finder = new ManifestFileFinder();
		$finder->setOptions(array(
			'name_regex'    => '/^([^_].*\.php)$/',
			'ignore_files'  => array('index.php', 'main.php', 'cli-script.php'),
			'ignore_tests'  => !$this->tests,
			'file_callback' => array($this, 'handleFile')
		));

		$finder->find($this->base);

		if($cache) {
			$index = array('$statics' => array());
			$bases = array();

			foreach ($this->statics as $class => $details) {
				if (in_array($class, self::$initial_classes)) {
					$index['$statics'][$class] = $details;
				}
				else {
					$base = $class;

					do {
						$parent = get_parent_class($base);
					}
					while ($parent != 'Object' && $parent != 'ViewableData' && $parent && ($base = $parent));

					$base = sha1($base);
					$bases[$base][$class] = $details;

					$index[$class] = array(
						'base' => $base,
						'path' => $details['path'],
						'mtime' => filemtime($details['path']),
					);
				}
			}

			foreach ($bases as $base => $details) {
				$this->cache->save($details, $this->key.'_'.$base);
			}

			$this->cache->save($index, $this->key);
		}
	}

	public function handleFile($basename, $pathname, $depth) {
		$parser = new SS_ConfigStaticManifest_Parser($pathname);
		$this->statics = array_merge($this->statics, $parser->parse());
	}

	public function getStatics() {
		return $this->statics;
	}
}

/**
 * A parser that processes a PHP file, using PHP's built in parser to get a string of tokens,
 * then processing them to find the static class variables, their access levels & values
 *
 * We can't do this using TokenisedRegularExpression because we need to keep track of state
 * as we process the token list (when we enter and leave a namespace or class, when we see
 * an access level keyword, etc)
 */
class SS_ConfigStaticManifest_Parser {

	protected $statics = array();

	protected $path;
	protected $tokens;
	protected $length;
	protected $pos;

	function __construct($path) {
		$this->path = $path;
		$file = file_get_contents($path);

		$this->tokens = token_get_all($file);
		$this->length = count($this->tokens);
		$this->pos = 0;
	}

	/**
	 * Get the next token to process, incrementing the pointer
	 *
	 * @param bool $ignoreWhitespace - if true will skip any whitespace tokens & only return non-whitespace ones
	 * @return null | int - Either the next token or null if there isn't one
	 */
	protected function next($ignoreWhitespace = true) {
		do {
			if($this->pos >= $this->length) return null;
			$next = $this->tokens[$this->pos++];
		}
		while($ignoreWhitespace && is_array($next) && $next[0] == T_WHITESPACE);

		return $next;
	}

	/**
	 * Parse the given file to find the static variables declared in it, along with their access & values
	 */
	function parse() {
		$depth = 0; $namespace = null; $class = null; $clsdepth = null; $access = 0;

		while($token = $this->next()) {
			$type = is_array($token) ? $token[0] : $token;

			if($type == T_CLASS) {
				$next = $this->next();

				if($next[0] != T_STRING) {
					user_error("Couldn\'t parse {$this->path} when building config static manifest", E_USER_ERROR);
				}

				$class = $next[1];
			}
			else if($type == T_NAMESPACE) {
				$next = $this->next();

				if($next[0] != T_STRING) {
					user_error("Couldn\'t parse {$this->path} when building config static manifest", E_USER_ERROR);
				}

				$namespace = $next[1];
			}
			else if($type == '{' || $type == T_CURLY_OPEN || $type == T_DOLLAR_OPEN_CURLY_BRACES){
				$depth += 1;
				if($class && !$clsdepth) $clsdepth = $depth;
			}
			else if($type == '}') {
				$depth -= 1;
				if($depth < $clsdepth) $class = $clsdepth = null;
				if($depth < 0) user_error("Hmm - depth calc wrong, hit negatives", E_USER_ERROR);
			}
			else if($type == T_PUBLIC || $type == T_PRIVATE || $type == T_PROTECTED) {
				$access = $type;
			}
			else if($type == T_STATIC) {
				if($class && $depth == $clsdepth) $this->parseStatic($access, $namespace ? $namespace.'\\'.$class : $class);
			}
			else {
				$access = '';
			}
		}

		return $this->statics;
	}

	/**
	 * During parsing we've found a "static" keyword. Parse out the variable names and value
	 * assignments that follow.
	 *
	 * Seperated out from parse partially so that we can recurse if there are multiple statics
	 * being declared in a comma seperated list
	 */
	function parseStatic($access, $class) {
		$variable = null;
		$value = '';

		while($token = $this->next()) {
			$type = is_array($token) ? $token[0] : $token;

			if($type == T_PUBLIC || $type == T_PRIVATE || $type == T_PROTECTED) {
				$access = $type;
			}
			else if($type == T_FUNCTION) {
				return;
			}
			else if($type == T_VARIABLE) {
				$variable = substr($token[1], 1); // Cut off initial "$"
			}
			else if($type == ';' || $type == ',' || $type == '=') {
				break;
			}
			else {
				echo "What's this?\n";
				print_r($token);
				return;
			}
		}

		if($token == '=') {
			$depth = 0;

			while($token = $this->next(false)){
				$type = is_array($token) ? $token[0] : $token;

				// Track array nesting depth
				if($type == T_ARRAY) {
					$depth += 1;
				}
				else if($type == ')') {
					$depth -= 1;
				}

				// Parse out the assignment side of a static declaration, ending on either a ';' or a ',' outside an array
				if($type == T_WHITESPACE) {
					$value .= ' ';
				}
				else if($type == ';' || ($type == ',' && !$depth)) {
					break;
				}
				// Statics can reference class constants with self:: (and that won't work in eval)
				else if($type == T_STRING && $token[1] == 'self') {
					$value .= $class;
				}
				else {
					$value .= is_array($token) ? $token[1] : $token;
				}
			}
		}

		if(!isset($this->statics[$class])) {
			$this->statics[$class] = array(
				'path' => $this->path,
				'statics' => array()
			);
		}

		$this->statics[$class][$variable] = array(
			'access' => $access,
			'value' => eval('return '.$value.';')
		);

		if($token == ',') $this->parseStatic($access, $class);
	}
}