# Path¶

Usage

use Path;

A file utilities library, specifically related to path operations

The Path module focuses on manipulation of the path to a file or directory. Also provided are constant values representing common idioms that may vary across operating systems (though rarely in the modern era), such as general references to a parent directory or the current directory.

Note

This module is currently missing the implementation for expandUser, normCase, Once those are implemented, it will be considered complete.

Operations which occur on the files or directories referred to by these paths may be found in FileSystem (for operations on the file) or IO (for operations within the file).

## Constant and Function Definitions¶

const curDir = "."

Represents generally the current directory. This starts as the directory where the program is being executed from.

const parentDir = ".."

Represents generally the parent directory.

const pathSep = "/"

Denotes the separator between a directory and its child.

proc absPath(name: string): string throws

Creates a normalized absolutized version of a path. On most platforms, when given a non-absolute path this function is equivalent to the following code:

normPath(joinPath(here.cwd(), name))

See normPath(), joinPath(), cwd() for details.

Warning

This function is unsafe for use in a parallel environment due to its reliance on cwd(). Another task on the current locale may change the current working directory at any time.

Arguments: Returns: name : string -- The path whose absolute path is desired. A normalized, absolutized version of the path specified. string Upon failure to get the current working directory.
proc file.absPath(): string throws

Creates a normalized absolutized version of the path in this file. On most platforms, when given a non-absolute path this function is equivalent to the following code:

normPath(joinPath(here.cwd(), file.path))

See normPath(), joinPath(), cwd(), path for details.

Warning

This method is unsafe for use in a parallel environment due to its reliance on cwd(). Another task on the current locale may change the current working directory at any time.

Returns: Return type: A normalized, absolutized version of the path for this file. string Upon failure to get the current working directory.
proc basename(name: string): string

Returns the basename of the file name provided. For instance:

writeln(basename("/foo/bar/baz")); // Prints "baz"
writeln(basename("/foo/bar/")); // Prints "", because of the empty string

Note that this is different from the Unix basename function.

Arguments: name : string -- A string file name. Note that this string does not have to be a valid file name, as the file itself will not be affected.
proc commonPath(in paths: string ...?n): string

Determines and returns the longest common path prefix of all the string pathnames provided.

Arguments: paths : string -- Any number of paths. The longest common path prefix. string
proc commonPath(paths: []): string

Determines and returns the longest common path prefix of all the string pathnames provided.

Arguments: paths : array -- Any number of paths as an array. The longest common path prefix. string
proc dirname(name: string): string

Returns the parent directory of the file name provided. For instance:

writeln(dirname("/foo/bar/baz")); // Prints "/foo/bar"
writeln(dirname("/foo/bar/")); // Also prints "/foo/bar"
Arguments: name : string -- A string file name. Note that this string does not have to be a valid file name, as the file itself will not be affected.
proc expandVars(path: string): string

Expands any environment variables in the path of the form $<name> or${<name>} into their values. If <name> does not exist, they are left in place. Returns the path which includes these expansions.

Arguments: path : string -- A string representation of a path, which may or may not include $or${}. path, having replaced all references to environment variables with their values. string
proc file.getParentName(): string throws

Returns the parent directory of the file record. For instance:

var myFile = open("/foo/bar/baz.txt", iomode.r);
writeln(myFile.getParentName()); // Prints "/foo/bar"

Will throw a SystemError if one occurs.

Returns: The parent directory of the file. string
proc isAbsPath(name: string): bool

Determines whether the path specified is an absolute path.

Note

This is currently only implemented in a Unix environment. It will not behave correctly in a non-Unix environment.

Arguments: name : string -- The path to be checked. true if name is an absolute path, false otherwise. bool
proc joinPath(in paths: string ...?n): string

Join and return one or more paths, putting precedent on the last absolute path seen. Return value is the concatenation of the paths with one directory separator following each non-empty argument except the last. Examples:

writeln(joinPath("/foo/bar", "/baz")); // Prints "/baz"
writeln(joinPath("/foo", "./baz")); // Prints "/foo/./baz"
writeln(joinPath("/foo/", "", "./baz")); // Prints "/foo/./baz"
Arguments: paths : string -- Any number of paths. The concatenation of the last absolute path with everything following it, or all the paths provided if no absolute path is present. string
proc normPath(name: string): string

Normalize a path by eliminating redundant separators and up-level references. The paths foo//bar, foo/bar/, foo/./bar, and foo/baz/../bar would all be changed to foo/bar.

Warning

May alter the meaning of paths containing symbolic links.

Note

Unlike its Python counterpart, this function does not (currently) change slashes to backslashes on Windows.

Arguments: name : string -- A potential path to collapse, possibly destroying the meaning of the path if symbolic links were included. The collapsed version of name. string
proc realPath(name: string): string throws

Given a path name, attempts to determine the canonical path referenced. This resolves and removes any curDir and parentDir uses present, as well as any symbolic links. Returns the result.

Will throw a SystemError if one occurs.

Arguments: name : string -- A path to resolve. If the path does not refer to a valid file or directory, an error will occur. A canonical version of the argument. string
proc file.realPath(): string throws

Determines the canonical path referenced by the file record performing this operation. This resolves and removes any curDir and parentDir uses present, as well as any symbolic links. Returns the result.

Will throw a SystemError if one occurs.

Returns: A canonical path to the file referenced by this file record. If the file record is not valid, an error will occur. string
proc relPath(name: string, start: string = curDir): string throws

Returns a relative filepath to name either from the current directory or an optional start directory. The filesystem is not accessed to verify the existence of the named path or the specified starting location.

Warning

This method is unsafe for use in a parallel environment due to its reliance on cwd(). Another task on the current locale may change the current working directory at any time.

Arguments: Returns: name : string -- A path which the caller would like to access. start : string -- The location from which access to name is desired. If no value is provided, defaults to curDir. The relative path to name from the current directory. string Upon failure to get the current working directory.
proc file.relPath(start: string = curDir): string throws

Returns a relative filepath to the path in this file either from the current directory or an optional start directory. The filesystem is not accessed to verify the existence of the named path or the specified starting location.

Warning

This method is unsafe for use in a parallel environment due to its reliance on cwd(). Another task on the current locale may change the current working directory at any time.

Arguments: Returns: start : string -- The location from which access to the path in this file is desired. If no value is provided, defaults to curDir. The relative filepath to the path in this file. string Upon failure to get the current working directory.
proc splitPath(name: string): (string, string)

Split name into a tuple that is equivalent to (dirname, basename). The second part of the tuple will never contain a slash. Examples:

writeln(splitPath("foo/bar")); // Prints "(foo, bar)"
writeln(splitPath("bar")); // Prints "(, bar)"
writeln(splitPath("foo/")); // Prints "(foo, )"
writeln(splitPath("")); // Prints "(, )"
writeln(splitPath("/")); // Prints "(/, )"

With the exception of a path of the empty string or just "/", the original path can be recreated from this function's returned parts by joining them with the path separator character, either explicitly or by calling joinPath:

var res = splitPath("foo/bar");
var dirnameVar = res(1);
var basenameVar = res(2);
writeln(dirnameVar + "/" + basenameVar); // Prints "foo/bar"
writeln(joinPath(dirnameVar, basenameVar)); // Prints "foo/bar"
Arguments: name : string -- Path to be split.