From ba6d8ad2617c2100021d6e3c949c0b9088f2667b Mon Sep 17 00:00:00 2001
From: Antoine Stevan <44101798+amtoine@users.noreply.github.com>
Date: Tue, 12 Sep 2023 21:59:31 +0200
Subject: [PATCH] add `std repeat` command to replace `"foo" * 3` (#10339)
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related to
- https://github.com/nushell/nushell/issues/10233
- https://github.com/nushell/nushell/pull/10293
- https://github.com/nushell/nushell/pull/10292

inspired by @kubouch

# Description
this PR adds a `repeat` command to the standard library

# User-Facing Changes
a new `repeat` command in `std`
```nushell
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"

Usage:
  > repeat <n>

Flags:
  -h, --help - Display the help message for this command

Parameters:
  n <int>: the number of repetitions, must be positive

Input/output types:
  ╭───┬───────┬───────────╮
  │ # │ input │  output   │
  ├───┼───────┼───────────┤
  │ 0 │ any   │ list<any> │
  ╰───┴───────┴───────────╯
```

# Tests + Formatting
a new test called `repeat_things` in `test_std.nu`

# After Submitting
---
 crates/nu-std/std/mod.nu        | 30 ++++++++++++++++++++++++++++++
 crates/nu-std/tests/test_std.nu | 11 +++++++++++
 2 files changed, 41 insertions(+)

diff --git a/crates/nu-std/std/mod.nu b/crates/nu-std/std/mod.nu
index 9ac30ec869..395d5b0393 100644
--- a/crates/nu-std/std/mod.nu
+++ b/crates/nu-std/std/mod.nu
@@ -294,3 +294,33 @@ Startup Time: ($nu.startup-time)
 export def pwd [] {
     $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)"
+                start: $span.start
+                end: $span.end
+            }
+        }
+    }
+
+    if $n == 0 {
+        return []
+    }
+
+    ..($n - 1) | each { $item }
+}
diff --git a/crates/nu-std/tests/test_std.nu b/crates/nu-std/tests/test_std.nu
index fcbc00fa48..6e82335aeb 100644
--- a/crates/nu-std/tests/test_std.nu
+++ b/crates/nu-std/tests/test_std.nu
@@ -44,3 +44,14 @@ def path_add [] {
 def banner [] {
     std assert ((std banner | lines | length) == 15)
 }
+
+#[test]
+def repeat_things [] {
+    std assert error { "foo" | std repeat -1 }
+
+    for x in ["foo", [1 2], {a: 1}] {
+        std assert equal ($x | std repeat 0) []
+        std assert equal ($x | std repeat 1) [$x]
+        std assert equal ($x | std repeat 2) [$x $x]
+    }
+}