nushell/crates/nu-std/std/mod.nu

# std.nu, `used` to load all standard library components

export module assert.nu
export module dirs.nu
export module dt.nu
export module formats.nu
export module help.nu
export module input.nu
export module iter.nu
export module log.nu
export module math.nu
export module xml.nu
export-env {
    use dirs.nu []
    use log.nu []
}

use dt.nu [datetime-diff, pretty-print-duration]

# Add the given paths to the PATH.
#
# # Example
# - adding some dummy paths to an empty PATH
# ```nushell
# >_ with-env { PATH: [] } {
#     std path add "foo"
#     std path add "bar" "baz"
#     std path add "fooo" --append
#
#     assert equal $env.PATH ["bar" "baz" "foo" "fooo"]
#
#     print (std path add "returned" --ret)
# }
# ╭───┬──────────╮
# │ 0 │ returned │
# │ 1 │ bar      │
# │ 2 │ baz      │
# │ 3 │ foo      │
# │ 4 │ fooo     │
# ╰───┴──────────╯
# ```
# - adding paths based on the operating system
# ```nushell
# >_ std path add {linux: "foo", windows: "bar", darwin: "baz"}
# ```
export def --env "path add" [
    --ret (-r)  # return $env.PATH, useful in pipelines to avoid scoping.
    --append (-a)  # append to $env.PATH instead of prepending to.
    ...paths  # the paths to add to $env.PATH.
] {
    let span = (metadata $paths).span
    let paths = $paths | flatten

    if ($paths | is-empty) or ($paths | length) == 0 {
        error make {msg: "Empty input", label: {
            text: "Provide at least one string or a record",
            span: $span
        }}
    }

    let path_name = if "PATH" in $env { "PATH" } else { "Path" }

    let paths = $paths | each {|p|
        let p = match ($p | describe | str replace --regex '<.*' '') {
            "string" => $p,
            "record" => { $p | get --ignore-errors $nu.os-info.name },
        }

        $p | path expand --no-symlink
    }

    if null in $paths or ($paths | is-empty) {
        error make {msg: "Empty input", label: {
            text: $"Received a record, that does not contain a ($nu.os-info.name) key",
            span: $span
        }}
    }

    load-env {$path_name: (
        $env
            | get $path_name
            | split row (char esep)
            | if $append { append $paths } else { prepend $paths }
    )}

    if $ret {
        $env | get $path_name
    }
}

# convert an integer amount of nanoseconds to a real duration
def "from ns" [] {
    [$in "ns"] | str join | into duration
}

# run a piece of `nushell` code multiple times and measure the time of execution.
#
# this command returns a benchmark report of the following form:
# ```
# record<
#   mean: duration
#   std: duration
#   times: list<duration>
# >
# ```
#
# > **Note**
# > `std bench --pretty` will return a `string`.
#
# # Examples
#     measure the performance of simple addition
#     > std bench { 1 + 2 } -n 10 | table -e
#     ╭───────┬────────────────────╮
#     │ mean  │ 4µs 956ns          │
#     │ std   │ 4µs 831ns          │
#     │       │ ╭───┬────────────╮ │
#     │ times │ │ 0 │ 19µs 402ns │ │
#     │       │ │ 1 │  4µs 322ns │ │
#     │       │ │ 2 │  3µs 352ns │ │
#     │       │ │ 3 │  2µs 966ns │ │
#     │       │ │ 4 │        3µs │ │
#     │       │ │ 5 │   3µs 86ns │ │
#     │       │ │ 6 │   3µs 84ns │ │
#     │       │ │ 7 │  3µs 604ns │ │
#     │       │ │ 8 │   3µs 98ns │ │
#     │       │ │ 9 │  3µs 653ns │ │
#     │       │ ╰───┴────────────╯ │
#     ╰───────┴────────────────────╯
#
#     get a pretty benchmark report
#     > std bench { 1 + 2 } --pretty
#     3µs 125ns +/- 2µs 408ns
export def bench [
    code: closure  # the piece of `nushell` code to measure the performance of
    --rounds (-n): int = 50  # the number of benchmark rounds (hopefully the more rounds the less variance)
    --verbose (-v) # be more verbose (namely prints the progress)
    --pretty # shows the results in human-readable format: "<mean> +/- <stddev>"
] {
    let times = (
        seq 1 $rounds | each {|i|
            if $verbose { print -n $"($i) / ($rounds)\r" }
            timeit { do $code } | into int | into float
        }
    )

    if $verbose { print $"($rounds) / ($rounds)" }

    let report = {
        mean: ($times | math avg | from ns)
        min: ($times | math min | from ns)
        max: ($times | math max | from ns)
        std: ($times | math stddev | from ns)
        times: ($times | each { from ns })
    }

    if $pretty {
        $"($report.mean) +/- ($report.std)"
    } else {
        $report
    }
}

# Print a banner for nushell with information about the project
export def banner [] {
let dt = (datetime-diff (date now) 2019-05-10T09:59:12-07:00)
$"(ansi green)     __  ,(ansi reset)
(ansi green) .--\(\)°'.' (ansi reset)Welcome to (ansi green)Nushell(ansi reset),
(ansi green)'|, . ,'   (ansi reset)based on the (ansi green)nu(ansi reset) language,
(ansi green) !_-\(_\\    (ansi reset)where all data is structured!

Please join our (ansi purple)Discord(ansi reset) community at (ansi purple)https://discord.gg/NtAbbGn(ansi reset)
Our (ansi green_bold)GitHub(ansi reset) repository is at (ansi green_bold)https://github.com/nushell/nushell(ansi reset)
Our (ansi green)Documentation(ansi reset) is located at (ansi green)https://nushell.sh(ansi reset)
(ansi cyan)Tweet(ansi reset) us at (ansi cyan_bold)@nu_shell(ansi reset)
Learn how to remove this at: (ansi green)https://nushell.sh/book/configuration.html#remove-welcome-message(ansi reset)

It's been this long since (ansi green)Nushell(ansi reset)'s first commit:
(pretty-print-duration $dt)

Startup Time: ($nu.startup-time)
"
}

# the cute and friendly mascot of Nushell :)
export def ellie [] {
    let ellie = [
        "     __  ,",
        " .--()°'.'",
        "'|, . ,'",
        " !_-(_\\",
    ]

    $ellie | str join "\n" | $"(ansi green)($in)(ansi reset)"
}

# Return the current working directory
export def pwd [
    --physical (-P) # resolve symbolic links
] {
    if $physical {
        $env.PWD | path expand
    } else {
        $env.PWD
    }
}

# repeat anything a bunch of times, yielding a list of *n* times the input
#
# # Examples
#     repeat a string
#     > "foo" | std repeat 3 | str join
#     "foofoofoo"
export def repeat [
    n: int  # the number of repetitions, must be positive
]: any -> list<any> {
    let item = $in

    if $n < 0 {
        let span = metadata $n | get span
        error make {
            msg: $"(ansi red_bold)invalid_argument(ansi reset)"
            label: {
                text: $"n should be a positive integer, found ($n)"
            	span: $span
            }
        }
    }

    if $n == 0 {
        return []
    }

    1..$n | each { $item }
}

# return a null device file.
#
# # Examples
#     run a command and ignore it's stderr output
#     > cat xxx.txt e> (null-device)
export def null-device []: nothing -> path {
    if ($nu.os-info.name | str downcase) == "windows" {
        '\\.\NUL'
    } else {
        "/dev/null"
    }
}