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Description:

fs shim

fs_shim #
A portable file system library to allow working on io, browser (though idb_shim) and memory (through idb_shim).

API supported #
It contains a subset of the io File/Directory API. Basically all sync methods are removed since
on the web indexedDB cannot be accessed in a synchronous way.
Classes

File (create, openWrite, openRead, writeAsBytes, writeAsString, copy)
Link (create, target)
Directory (create, list)
FileSystem (file, link, directory, type, isFile, isDirectory, isLink)
FileSystemEntity (path, exists, delete, rename, absolute, isAbsolute, state, parent)
FileStat
FileSystemEntityType,
FileSystemException,

Static method

Directory.current
FileSystemEntity.isFile
FileSystemEntity.isDirectory
FileSystemEntity.isLink

Static and File/Directory/Link constructor uses fileSystemDefault which is platform dependent (web or io).
Usage #
In memory #
A simple usage example:
import 'package:fs_shim/fs_shim.dart';
import 'package:path/path.dart';

Future main() async {
final fs = fileSystemMemory;

// Create a top level directory
final dir = fs.directory('/dir');

// and a file in it
final file = fs.file(join(dir.path, 'file'));

// create a file
await file.create(recursive: true);
await file.writeAsString('Hello world!');

// read a file
print('file: ${await file.readAsString()}');

// use a file link if supported
if (fs.supportsFileLink) {
final link = fs.link(join(dir.path, 'link'));
await link.create(file.path);

print('link: ${await fs.file(link.path).readAsString()}');
}

// list dir content
print(await dir.list(recursive: true, followLinks: true).toList());
}
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Using IO API #
Using fs_shim.dart
You can simply replace in the above example:
final fs = fileSystemMemory;
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by
final fs = fileSystemIo;
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If you only target io, you can still be able to use File and Directory constructor, replace
import 'dart:io'
hide
Directory,
File,
Link,
FileSystemEntity,
FileMode,
FileStat,
OSError,
FileSystemException,
FileSystemEntityType;

import 'package:fs_shim/fs_shim.dart';
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by
import 'package:fs_shim/fs_io.dart';
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Then a reduced set of the IO API can be used, same source code that might requires some cleanup if you import from
existing code
Simple example
import 'package:fs_shim/fs_shim.dart';
import 'package:path/path.dart';

Future main() async {
await exampleInit();
final fs = fileSystemDefault;
// safe place when running from package root
final dirPath = join(Directory.current.path, 'test_out', 'example', 'dir');

// Create a top level directory
final dir = Directory(dirPath);
print('dir: $dir');
// delete its content
if (await dir.exists()) {
await dir.delete(recursive: true);
}

// and a file in it
final file = File(join(dir.path, 'file'));

// create a file
await file.create(recursive: true);
await file.writeAsString('Hello world!');

// read a file
print('file: ${await file.readAsString()}');

// use a file link if supported
if (fs.supportsFileLink) {
var link = Link(join(dir.path, 'link'));

await link.create(basename(file.path));
var linkFile = File(link.path);
print('link: ${await linkFile.readAsString()}');
}

// list dir content
print(await dir.list(recursive: true, followLinks: true).toList());
}
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Browser usage #
You can simply replace in the in memory example:
final fs = fileSystemMemory;
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by
final fs = fileSystemWeb;
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Default implementation on browser uses fileSystemWeb
Random access support. #
Random access is supported since version 2.1.0. Default web implementation is not optimized for random access support (it might change in the future).
You can specify a paging parameter (initial testing is good in some scenario with a 16Kb page, you might tune it for your needs).
import 'package:fs_shim/fs_browser.dart';

// Use default paging 16Kb
final fs =
fileSystemWeb.withIdbOptions(options: FileSystemIdbOptions.pageDefault);
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Storage remains compatible if the options is changed.
Utilities #

Lightweight glob support (**, * and ? in a posix style path)
Copy utilities (copy files, directories recursively)

Testing #
Dev dependencies #
Stable
fs_shim: any
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Bleeding age
fs_shim:
git: https://github.com/tekartik/fs_shim.dart
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Features and bugs #

On windows file links are not supported (fs.supportsFileLink returns false)
On windows directory link target are absolutes
On the web, the size of the file system is limited by the limit size of indexedDB databases (browser dependent)