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