A Word-Based Compression Technique for Text Files.

Fuente: ERIC Institute of Education Sciences

Saved in:

Bibliographic Details
Main Authors:	Vernor, Russel L., III, Weiss, Stephen F.
Format:	Recurso educativo Open Access
Language:	en
Published:	1978
Subjects:	Databases Information Processing Information Retrieval Information Storage
Online Access:	Acceder al recurso
Tags:	Add Tag No Tags, Be the first to tag this record!

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author	Vernor, Russel L., III Weiss, Stephen F.
author_facet	Vernor, Russel L., III Weiss, Stephen F. Vernor, Russel L., III Weiss, Stephen F.
collection	Education Resources Information Center
contents	A Word-Based Compression Technique for Text Files. Vernor, Russel L., III Weiss, Stephen F. Databases Information Processing Information Retrieval Information Storage Presents a word-based technique for storing natural language text in compact form. The compressed text consists of a dictionary and a text that is a combination of actual running text and pointers to the dictionary. This technique has shown itself to be effective for both text storage and retrieval. (VT)
format	Recurso educativo Open Access
id	eric_EJ190879
institution	ERIC Institute of Education Sciences
language	en
publishDate	1978
record_format	eric
spellingShingle	A Word-Based Compression Technique for Text Files. Vernor, Russel L., III Weiss, Stephen F. Databases Information Processing Information Retrieval Information Storage A Word-Based Compression Technique for Text Files. Vernor, Russel L., III Weiss, Stephen F. Databases Information Processing Information Retrieval Information Storage Presents a word-based technique for storing natural language text in compact form. The compressed text consists of a dictionary and a text that is a combination of actual running text and pointers to the dictionary. This technique has shown itself to be effective for both text storage and retrieval. (VT)
title	A Word-Based Compression Technique for Text Files.
topic	Databases Information Processing Information Retrieval Information Storage
url	https://eric.ed.gov/?id=EJ190879

if (filemtime($filename) + $maxlifetime < time()) { unlink($filename); $count++; } } return $count; } /** * A function that is called internally when session data is to be saved. * * @param string $sessId The current session ID * @param string $data The session data to write * * @return bool */ protected function saveSession($sessId, $data): bool { $sessFile = $this->path . '/sess_' . $sessId; if ($handle = fopen($sessFile, 'w')) { $return = false; // Lock the file for exclusive access to avoid issues with multiple // processes writing session simultaneously: if (flock($handle, LOCK_EX)) { $return = fwrite($handle, $data); // Make sure that there's no trailing data by truncating the file to // the correct length: ftruncate($handle, strlen($data)); fflush($handle); flock($handle, LOCK_UN); } fclose($handle); if ($return !== false) { return true; } } // If we got this far, something went wrong with the file output... // It is tempting to throw an exception here, but this code is called // outside of the context of exception handling, so all we can do is // echo a message.

// Anecdotal testing Today and Yesterday seems to indicate destroy() // is called by the garbage collector and everything is good. // Something to keep in mind though. return 0; } /** * Write function that is called when session data is to be saved. * * @param string $sessId The current session ID * @param string $data The session data to write * * @return bool */ public function write($sessId, $data): bool { if ($this->writesDisabled) { return true; } return $this->saveSession($sessId, $data); } /** * A function that is called internally when session data is to be saved. * * @param string $sessId The current session ID * @param string $data The session data to write * * @return bool */ abstract protected function saveSession($sessId, $data): bool; }

* * @return void */ public function writeClose() { // The assumption is that we're using PHP's ext/session. // session_write_close() will actually overwrite $_SESSION with an // empty array on completion -- which leads to a mismatch between what // is in the storage object and $_SESSION. To get around this, we // temporarily reset $_SESSION to an array, and then re-link it to // the storage object. // // Additionally, while you _can_ write to $_SESSION following a // session_write_close() operation, no changes made to it will be // flushed to the session handler. As such, we now mark the storage // object isImmutable. $storage = $this->getStorage(); if (! $storage->isImmutable()) { $_SESSION = $storage->toArray(true); session_write_close(); $storage->fromArray($_SESSION); $storage->markImmutable(); } } /** * Attempt to set the session name * * If the session has already been started, or if the name provided fails * validation, an exception will be raised. * * @param string $name * @return SessionManager * @throws Exception\InvalidArgumentException */ public function setName($name) { if ($this->sessionExists()) { throw new Exception\InvalidArgumentException( 'Cannot set session name after a session has already started'

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