path

Documentation

Overview

Package path implements utility routines for manipulating filename paths as defined by targetted operating systems, and also paths that always use forward slashes regardless of the operating system, such as URLs.

Index

• Variables
• func Base(path string, os OS) string
• func Clean(path string, os OS) string
• func Dir(path string, os OS) string
• func Ext(path string, os OS) string
• func FromSlash(path string, os OS) string
• func IsAbs(path string, os OS) bool
• func Join(elem []string, os OS) string
• func Match(pattern, name string, o OS) (matched bool, err error)
• func Rel(basepath, targpath string, os OS) (string, error)
• func Resolve(dir, sub string, os OS) string
• func Split(path string, os OS) []string
• func SplitList(path string, os OS) []string
• func ToSlash(path string, os OS) string
• func VolumeName(path string, os OS) string
• type OS

Examples

• Base
• Dir
• Ext
• IsAbs
• Join
• Match
• Rel
• Split
• SplitList

Variables

var ErrBadPattern = errors.New("syntax error in pattern")

ErrBadPattern indicates a pattern was malformed.

Functions

func Base

func Base(path string, os OS) string

Base returns the last element of path. Trailing path separators are removed before extracting the last element. If the path is empty, Base returns ".". If the path consists entirely of separators, Base returns a single separator. The default value for os is Unix.

Example

package main

import (
	"fmt"

	"cuelang.org/go/pkg/path"
)

func main() {
	fmt.Println("On Unix:")
	fmt.Println(path.Base("/foo/bar/baz.js", path.Unix))
	fmt.Println(path.Base("/foo/bar/baz", path.Unix))
	fmt.Println(path.Base("/foo/bar/baz/", path.Unix))
	fmt.Println(path.Base("dev.txt", path.Unix))
	fmt.Println(path.Base("../todo.txt", path.Unix))
	fmt.Println(path.Base("..", path.Unix))
	fmt.Println(path.Base(".", path.Unix))
	fmt.Println(path.Base("/", path.Unix))
	fmt.Println(path.Base("", path.Unix))

}

Output:

On Unix:
baz.js
baz
baz
dev.txt
todo.txt
..
.
/
.

func Clean

func Clean(path string, os OS) string

Clean returns the shortest path name equivalent to path by purely lexical processing. The default value for os is Unix. It applies the following rules iteratively until no further processing can be done:

1. Replace multiple Separator elements with a single one.
2. Eliminate each . path name element (the current directory).
3. Eliminate each inner .. path name element (the parent directory) along with the non-.. element that precedes it.
4. Eliminate .. elements that begin a rooted path: that is, replace "/.." by "/" at the beginning of a path, assuming Separator is '/'.

The returned path ends in a slash only if it represents a root directory, such as "/" on Unix or `C:\` on Windows.

Finally, any occurrences of slash are replaced by Separator.

If the result of this process is an empty string, Clean returns the string ".".

See also Rob Pike, “Lexical File Names in Plan 9 or Getting Dot-Dot Right,” https://9p.io/sys/doc/lexnames.html

func Dir

func Dir(path string, os OS) string

Dir returns all but the last element of path, typically the path's directory. After dropping the final element, Dir calls Clean on the path and trailing slashes are removed. If the path is empty, Dir returns ".". If the path consists entirely of separators, Dir returns a single separator. The returned path does not end in a separator unless it is the root directory. The default value for os is Unix.

Example

package main

import (
	"fmt"

	"cuelang.org/go/pkg/path"
)

func main() {
	fmt.Println("On Unix:")
	fmt.Println(path.Dir("/foo/bar/baz.js", path.Unix))
	fmt.Println(path.Dir("/foo/bar/baz", path.Unix))
	fmt.Println(path.Dir("/foo/bar/baz/", path.Unix))
	fmt.Println(path.Dir("/dirty//path///", path.Unix))
	fmt.Println(path.Dir("dev.txt", path.Unix))
	fmt.Println(path.Dir("../todo.txt", path.Unix))
	fmt.Println(path.Dir("..", path.Unix))
	fmt.Println(path.Dir(".", path.Unix))
	fmt.Println(path.Dir("/", path.Unix))
	fmt.Println(path.Dir("", path.Unix))

}

Output:

On Unix:
/foo/bar
/foo/bar
/foo/bar/baz
/dirty/path
.
..
.
.
/
.

func Ext

func Ext(path string, os OS) string

Ext returns the file name extension used by path. The extension is the suffix beginning at the final dot in the final element of path; it is empty if there is no dot. The default value for os is Unix.

Example

package main

import (
	"fmt"

	"cuelang.org/go/pkg/path"
)

func main() {
	fmt.Printf("No dots: %q\n", path.Ext("index", "unix"))
	fmt.Printf("One dot: %q\n", path.Ext("index.js", "unix"))
	fmt.Printf("Two dots: %q\n", path.Ext("main.test.js", "unix"))
}

Output:

No dots: ""
One dot: ".js"
Two dots: ".js"

func FromSlash

func FromSlash(path string, os OS) string

FromSlash returns the result of replacing each slash ('/') character in path with a separator character. Multiple slashes are replaced by multiple separators.

func IsAbs

func IsAbs(path string, os OS) bool

IsAbs reports whether the path is absolute. The default value for os is Unix. Note that because IsAbs has a default value, it cannot be used as a validator.

Example

package main

import (
	"fmt"

	"cuelang.org/go/pkg/path"
)

func main() {
	fmt.Println("On Unix:")
	fmt.Println(path.IsAbs("/home/gopher", path.Unix))
	fmt.Println(path.IsAbs(".bashrc", path.Unix))
	fmt.Println(path.IsAbs("..", path.Unix))
	fmt.Println(path.IsAbs(".", path.Unix))
	fmt.Println(path.IsAbs("/", path.Unix))
	fmt.Println(path.IsAbs("", path.Unix))

}

Output:

On Unix:
true
false
false
false
true
false

func Join

func Join(elem []string, os OS) string

Join joins any number of path elements into a single path, separating them with an OS specific Separator. Empty elements are ignored. The result is Cleaned. However, if the argument list is empty or all its elements are empty, Join returns an empty string. On Windows, the result will only be a UNC path if the first non-empty element is a UNC path. The default value for os is Unix.

Example

package main

import (
	"fmt"

	"cuelang.org/go/pkg/path"
)

func main() {
	fmt.Println("On Unix:")
	fmt.Println(path.Join([]string{"a", "b", "c"}, path.Unix))
	fmt.Println(path.Join([]string{"a", "b/c"}, path.Unix))
	fmt.Println(path.Join([]string{"a/b", "c"}, path.Unix))
	fmt.Println(path.Join([]string{"a/b", "/c"}, path.Unix))

	fmt.Println(path.Join([]string{"a/b", "../../../xyz"}, path.Unix))

}

Output:

On Unix:
a/b/c
a/b/c
a/b/c
a/b/c
../xyz

func Match

func Match(pattern, name string, o OS) (matched bool, err error)

Match reports whether name matches the shell file name pattern. The pattern syntax is:

pattern:
	{ term }
term:
	'*'         matches any sequence of non-Separator characters
	'?'         matches any single non-Separator character
	'[' [ '^' ] { character-range } ']'
	            character class (must be non-empty)
	c           matches character c (c != '*', '?', '\\', '[')
	'\\' c      matches character c

character-range:
	c           matches character c (c != '\\', '-', ']')
	'\\' c      matches character c
	lo '-' hi   matches character c for lo <= c <= hi

Match requires pattern to match all of name, not just a substring. The only possible returned error is ErrBadPattern, when pattern is malformed.

On Windows, escaping is disabled. Instead, '\\' is treated as path separator.

A pattern may not contain '**', as a wildcard matching separator characters is not supported at this time.

Example

package main

import (
	"fmt"

	"cuelang.org/go/pkg/path"
)

func main() {
	fmt.Println("On Unix:")
	fmt.Println(path.Match("/home/catch/*", "/home/catch/foo", path.Unix))
	fmt.Println(path.Match("/home/catch/*", "/home/catch/foo/bar", path.Unix))
	fmt.Println(path.Match("/home/?opher", "/home/gopher", path.Unix))
	fmt.Println(path.Match("/home/\\*", "/home/*", path.Unix))

}

Output:

On Unix:
true <nil>
false <nil>
true <nil>
true <nil>

func Rel

func Rel(basepath, targpath string, os OS) (string, error)

Rel returns a relative path that is lexically equivalent to targpath when joined to basepath with an intervening separator. That is, Join(basepath, Rel(basepath, targpath)) is equivalent to targpath itself. On success, the returned path will always be relative to basepath, even if basepath and targpath share no elements. An error is returned if targpath can't be made relative to basepath or if knowing the current working directory would be necessary to compute it. Rel calls Clean on the result. The default value for os is Unix.

Example

package main

import (
	"fmt"

	"cuelang.org/go/pkg/path"
)

func main() {
	paths := []string{
		"/a/b/c",
		"/b/c",
		"./b/c",
	}
	base := "/a"

	fmt.Println("On Unix:")
	for _, p := range paths {
		rel, err := path.Rel(base, p, path.Unix)
		fmt.Printf("%q: %q %v\n", p, rel, err)
	}

}

Output:

On Unix:
"/a/b/c": "b/c" <nil>
"/b/c": "../b/c" <nil>
"./b/c": "" Rel: can't make ./b/c relative to /a

func Resolve

func Resolve(dir, sub string, os OS) string

Resolve reports the path of sub relative to dir. If sub is an absolute path, or if dir is empty, it will return sub. If sub is empty, it will return dir. Resolve calls Clean on the result. The default value for os is Unix.

func Split

func Split(path string, os OS) []string

Split splits path immediately following the final slash and returns them as the list [dir, file], separating it into a directory and file name component. If there is no slash in path, Split returns an empty dir and file set to path. The returned values have the property that path = dir+file. The default value for os is Unix.

Example

package main

import (
	"fmt"

	"cuelang.org/go/pkg/path"
)

func main() {
	paths := []string{
		"/home/arnie/amelia.jpg",
		"/mnt/photos/",
		"rabbit.jpg",
		"/usr/local//go",
	}
	fmt.Println("On Unix:")
	for _, p := range paths {
		pair := path.Split(p, path.Unix)
		fmt.Printf("input: %q\n\tdir: %q\n\tfile: %q\n", p, pair[0], pair[1])
	}
}

Output:

On Unix:
input: "/home/arnie/amelia.jpg"
	dir: "/home/arnie/"
	file: "amelia.jpg"
input: "/mnt/photos/"
	dir: "/mnt/photos/"
	file: ""
input: "rabbit.jpg"
	dir: ""
	file: "rabbit.jpg"
input: "/usr/local//go"
	dir: "/usr/local//"
	file: "go"

func SplitList

func SplitList(path string, os OS) []string

SplitList splits a list of paths joined by the OS-specific ListSeparator, usually found in PATH or GOPATH environment variables. Unlike strings.Split, SplitList returns an empty slice when passed an empty string.

Example

package main

import (
	"fmt"

	"cuelang.org/go/pkg/path"
)

func main() {
	fmt.Println("On Unix:", path.SplitList("/a/b/c:/usr/bin", path.Unix))
}

Output:

On Unix: [/a/b/c /usr/bin]

func ToSlash

func ToSlash(path string, os OS) string

ToSlash returns the result of replacing each separator character in path with a slash ('/') character. Multiple separators are replaced by multiple slashes.

func VolumeName

func VolumeName(path string, os OS) string

VolumeName returns leading volume name. Given "C:\foo\bar" it returns "C:" on Windows. Given "\\host\share\foo" it returns "\\host\share". On other platforms it returns "". The default value for os is Windows.

Types

type OS

type OS string

OS must be a valid runtime.GOOS value or "unix".

const (
	Unix    OS = "unix"
	Windows OS = "windows"
	Plan9   OS = "plan9"
)