silverstripe-textextraction/code/extractors/FileTextExtractor.php
2015-11-18 17:07:31 +13:00

146 lines
3.7 KiB
PHP

<?php
/**
* A decorator for File or a subclass that provides a method for extracting full-text from the file's external contents.
* @author mstephens
*
*/
abstract class FileTextExtractor extends Object
{
/**
* Set priority from 0-100.
* The highest priority extractor for a given content type will be selected.
*
* @config
* @var integer
*/
private static $priority = 50;
/**
* Cache of extractor class names, sorted by priority
*
* @var array
*/
protected static $sorted_extractor_classes = null;
/**
* Gets the list of prioritised extractor classes
*
* @return array
*/
protected static function get_extractor_classes()
{
// Check cache
if (self::$sorted_extractor_classes) {
return self::$sorted_extractor_classes;
}
// Generate the sorted list of extractors on demand.
$classes = ClassInfo::subclassesFor("FileTextExtractor");
array_shift($classes);
$classPriorities = array();
foreach ($classes as $class) {
$classPriorities[$class] = Config::inst()->get($class, 'priority');
}
arsort($classPriorities);
// Save classes
$sortedClasses = array_keys($classPriorities);
return self::$sorted_extractor_classes = $sortedClasses;
}
/**
* Get the text file extractor for the given class
*
* @param string $class
* @return FileTextExtractor
*/
protected static function get_extractor($class)
{
return Injector::inst()->get($class);
}
/**
* Attempt to detect mime type for given file
*
* @param string $path
* @return string Mime type if found
*/
protected static function get_mime($path)
{
$file = new Symfony\Component\HttpFoundation\File\File($path);
return $file->getMimeType();
}
/**
* @param string $path
* @return FileTextExtractor|null
*/
public static function for_file($path)
{
if (!file_exists($path) || is_dir($path)) {
return;
}
$extension = pathinfo($path, PATHINFO_EXTENSION);
$mime = self::get_mime($path);
foreach (self::get_extractor_classes() as $className) {
$extractor = self::get_extractor($className);
// Skip unavailable extractors
if (!$extractor->isAvailable()) {
continue;
}
// Check extension
if ($extension && $extractor->supportsExtension($extension)) {
return $extractor;
}
// Check mime
if ($mime && $extractor->supportsMime($mime)) {
return $extractor;
}
}
}
/**
* Checks if the extractor is supported on the current environment,
* for example if the correct binaries or libraries are available.
*
* @return boolean
*/
abstract public function isAvailable();
/**
* Determine if this extractor supports the given extension.
* If support is determined by mime/type only, then this should return false.
*
* @param string $extension
* @return boolean
*/
abstract public function supportsExtension($extension);
/**
* Determine if this extractor suports the given mime type.
* Will only be called if supportsExtension returns false.
*
* @param string $mime
* @return boolean
*/
abstract public function supportsMime($mime);
/**
* Given a file path, extract the contents as text.
*
* @param string $path
* @return string
*/
abstract public function getContent($path);
}
class FileTextExtractor_Exception extends Exception
{
}