|author||Natalie Weizenbaum <firstname.lastname@example.org>||Mon Jun 04 21:09:27 2018 -0400|
|committer||GitHub <email@example.com>||Mon Jun 04 21:09:27 2018 -0400|
Merge pull request #40 from dart-lang/path-map Add PathMap and PathSet classes
A comprehensive, cross-platform path manipulation library for Dart.
The path package provides common operations for manipulating paths: joining, splitting, normalizing, etc.
We‘ve tried very hard to make this library do the “right” thing on whatever platform you run it on, including in the browser. When you use the top-level functions, it will assume the current platform’s path style and work with that. If you want to explicitly work with paths of a specific style, you can construct a
p.Context for that style.
The path library was designed to be imported with a prefix, though you don‘t have to if you don’t want to:
import 'package:path/path.dart' as p;
The most common way to use the library is through the top-level functions. These manipulate path strings based on your current working directory and the path style (POSIX, Windows, or URLs) of the host platform. For example:
This calls the top-level [join] function to join “directory” and “file.txt” using the current platform's directory separator.
If you want to work with paths for a specific platform regardless of the underlying platform that the program is running on, you can create a Context and give it an explicit [Style]:
var context = new p.Context(style: Style.windows); context.join("directory", "file.txt");
This will join “directory” and “file.txt” using the Windows path separator, even when the program is run on a POSIX machine.
path package is used by many Dart packages, and as such it strives for a very high degree of stability. For the same reason, though, releasing a new major version would probably cause a lot of versioning pain, so some flexibility is necessary.
We try to guarantee that operations with valid inputs and correct output will not change. Operations where one or more inputs are invalid according to the semantics of the corresponding platform may produce different output over time. Operations for which
path produces incorrect output will also change so that we can fix bugs.
path package‘s URL handling is based on the WHATWG URL spec. This is a living standard, and some parts of it haven’t yet been entirely solidified by vendor support. The
path package reserves the right to change its URL behavior if the underlying specification changes, although if the change is big enough to break many valid uses we may elect to treat it as a breaking change anyway.
path package runs on the Dart VM and in the browser under both dart2js and Dartium. On the browser,
window.location.href is used as the current path.
When you have path objects, then every API that takes a path has to decide if it accepts strings, path objects, or both.
Accepting strings is the most convenient, but then it seems weird to have these path objects that aren‘t actually accepted by anything that needs a path. Once you’ve created a path, you have to always call
.toString() on it before you can do anything useful with it.
Requiring objects forces users to wrap path strings in these objects, which is tedious. It also means coupling that API to whatever library defines this path class. If there are multiple “path” libraries that each define their own path types, then any library that works with paths has to pick which one it uses.
Taking both means you can‘t type your API. That defeats the purpose of having a path type: why have a type if your APIs can’t annotate that they expect it?
Given that, we've decided this library should simply treat paths as strings.
We believe this library handles most of the corner cases of Windows paths (POSIX paths are generally pretty straightforward):
It understands that both “/” and “\” are valid path separators, not just “\”.
It can accurately tell if a path is absolute based on drive-letters or UNC prefix.
It understands that “/foo” is not an absolute path on Windows.
It knows that “C:\foo\one.txt” and “c:/foo\two.txt” are two files in the same directory.
If you use this package in a browser, then it considers the “platform” to be the browser itself and uses URL strings to represent “browser paths”.