luau-path

A Luau library to handle file paths based on the Rust path library.

The library can be configured to use unix or windows style separator using the global variable SYS_PATH_SEPARATOR. The global should be defined to '/' or '\'.

When the global is not defined, it will default to '/'. If a LUA_ENV global variable is set to lune, the path separator will be inferred from lune's process built-in library.

Installation

Add luau-path in your dependencies:

yarn add luau-path

Or if you are using npm:

npm install luau-path

Content

This libary exports a Path class and the AsPath type.

local PathModule = require('@pkg/luau-path')

local Path = PathModule.Path

type Path = PathModule.Path
type AsPath = PathModule.AsPath

Constructors:

• Path.new
• Path.from

Static functions:

• Path.is

Path methods:

• ancestors
• clear
• components
• endsWith
• equal
• extension
• fileName
• filePrefix
• fileStem
• hasRoot
• isAbsolute
• isRelative
• join
• parent
• pop
• push
• setExtension
• setFileName
• startsWith
• stripPrefix
• toPathBuf
• toString
• withFileName
• withExtension

AsPath Type

type AsPath = string | Path | Components

Path.new

function Path.new(path: string): Path

Creates a new path from the given string.

Path.from

function Path.from(path: AsPath): Path

Creates a new path from a string or a Components iterator, or return the given Path object.

This function errors if the value does not satisfy the AsPath type.

Path.is

function Path.new(value: unknown): boolean

Returns true if the given value is a Path.

toString

function Path:toString(): string

Converts the path to a string representation.

toPathBuf

function Path:toPathBuf(): Path

Creates a new Path object that is a copy of the current path.

isAbsolute

function Path:isAbsolute(): boolean

Returns true if the Path is absolute, i.e., if it is independent of the current directory.

• On Unix, a path is absolute if it starts with the root, so isAbsolute and hasRoot are equivalent.
• On Windows, a path is absolute if it has a prefix and starts with the root: c:\windows is absolute, while c:temp and \temp are not.

isRelative

function Path:isRelative(): boolean

Returns true if the Path is relative, i.e., not absolute.

See isAbsolute's documentation for more details.

Examples

assert(Path.new("foo.txt"):isRelative())

hasRoot

function Path:hasRoot(): boolean

Returns true if the Path has a root.

• On Unix, a path has a root if it begins with /.
• On Windows, a path has a root if it:
  • has no prefix and begins with a separator, e.g., \windows
  • has a prefix followed by a separator, e.g., c:\windows but not c:windows
  • has any non-disk prefix, e.g., \\server\share

Examples

assert(Path.new("/etc/passwd"):hasRoot())

parent

function Path:parent(): Path?

Returns the Path without its final component, if there is one.

This means it returns "" for relative paths with one component.

Returns nil if the path terminates in a root or prefix, or if it’s the empty string.

ancestors

function Path:ancestors(): Ancestors

Produces an iterator over Path and its ancestors.

The iterator will yield the Path that is returned if the parent method is used zero or more times. That means, the iterator will yield self, self:parent(), self:parent():parent() and so on. If the parent method returns nil, the iterator will do likewise. The iterator will always yield at least one value, namely self.

fileName

function Path:fileName(): string?

Returns the final component of the Path, if there is one.

If the path is a normal file, this is the file name. If it’s the path of a directory, this is the directory name.

Returns nil if the path terminates in ...

stripPrefix

function Path:stripPrefix(base: AsPath): Path?

Returns a path that, when joined onto base, yields self.

If base is not a prefix of self (i.e., startsWith returns false), returns nil.

startsWith

function Path:startsWith(base: AsPath): boolean

Determines whether base is a prefix of self.

Only considers whole path components to match.

endsWith

function Path:endsWith(child: AsPath): boolean

Determines whether child is a suffix of self.

Only considers whole path components to match.

fileStem

function Path:fileStem(): string?

Extracts the stem (non-extension) portion of self:fileName().

The stem is:

• nil, if there is no file name;
• The entire file name if there is no embedded .;
• The entire file name if the file name begins with . and has no other .s within;
• Otherwise, the portion of the file name before the final .

See Also

This method is similar to filePrefix, which extracts the portion of the file name before the first .

filePrefix

function Path:filePrefix(): string?

Extracts the prefix of self:fileName().

The prefix is:

• nil, if there is no file name;
• The entire file name if there is no embedded .;
• The portion of the file name before the first non-beginning .;
• The entire file name if the file name begins with . and has no other .s within;
• The portion of the file name before the second . if the file name begins with .

See Also

This method is similar to fileStem, which extracts the portion of the file name before the last .

extension

function Path:extension(): string?

Extracts the extension (without the leading dot) of self:fileName(), if possible.

The extension is:

• nil, if there is no file name;
• nil, if there is no embedded .;
• nil, if the file name begins with . and has no other .s within;
• Otherwise, the portion of the file name after the final .

join

function Path:join(path: AsPath): Path

Creates a new Path with path adjoined to self.

If path is absolute, it replaces the current path.

See push for more details on what it means to adjoin a path.

withFileName

function Path:withFileName(fileName: string): Path

Creates a new Path like self but with the given file name.

See setFileName for more details.

withExtension

function Path:withExtension(extension: string): Path

Creates a new Path like self but with the given extension.

See setExtension for more details.

components

function Path:components(): Components

Produces an iterator over the Components of the path.

When parsing the path, there is a small amount of normalization:

• Repeated separators are ignored, so a/b and a//b both have a and b as components.
• Occurrences of . are normalized away, except if they are at the beginning of the path. For example, a/./b, a/b/, a/b/. and a/b all have a and b as components, but ./a/b starts with an additional CurDir component.
• A trailing slash is normalized away, /a/b and /a/b/ are equivalent.

Note that no other normalization takes place; in particular, a/c and a/b/../c are distinct, to account for the possibility that b is a symbolic link (so its parent isn't a).

equal

function Path:equal(other: Path): boolean

Returns true if the current path is equal to the other path.

push

function Path:push(path: AsPath): ()

Extends self with path.

If path is absolute, it replaces the current path.

On Windows:

• if path has a root but no prefix (e.g., \windows), it replaces everything except for the prefix (if any) of self.
• if path has a prefix but no root, it replaces self.
• if self has a verbatim prefix (e.g. \\?\C:\windows) and path is not empty, the new path is normalized: all references to . and .. are removed.

Consider using join if you need a new Path instead of using this function on a cloned Path.

pop

function Path:pop(): boolean

Truncates self to self:parent().

Returns false and does nothing if self:parent() is nil. Otherwise, returns true.

setFileName

function Path:setFileName(fileName: string): ()

Updates self:fileName() to fileName.

If self:fileName() was nil, this is equivalent to pushing fileName.

Otherwise it is equivalent to calling pop and then pushing fileName. The new path will be a sibling of the original path. (That is, it will have the same parent.)

setExtension

function Path:setExtension(extension: string): boolean

Updates self:extension() to extension or to nil if extension is empty.

Returns false and does nothing if self:fileName() is nil, returns true and updates the extension otherwise.

If self:extension() is nil, the extension is added; otherwise it is replaced.

If extension is the empty string, self:extension() will be None afterwards, not "".

Caveats

The new extension may contain dots and will be used in its entirety, but only the part after the final dot will be reflected in self:extension().

If the file stem contains internal dots and extension is empty, part of the old file stem will be considered the new self:extension().

clear

function Path:clear(): ()

Clears the path, making it an empty path.

License

This project is available under the MIT license. See LICENSE.txt for details.

Other Lua Environments Support

If you would like to use this library on a Lua environment, where it is currently incompatible, open an issue (or comment on an existing one) to request the appropriate modifications.

The library uses darklua to process its code.