feat(std): add comparison support to bench command (#15843)

# Description

Like [hyperfine](https://github.com/sharkdp/hyperfine), I have added the
option to the `bench` command to benchmark multiple commands and then
compare the results.

```
→ bench { ls -a | is-empty } { fd | is-empty }
 # |         code         |       mean       |       min       |       max        |     std     | ratio
---+----------------------+------------------+-----------------+------------------+-------------+-------
 0 | { ls -a | is-empty } |  3ms 816µs 562ns | 3ms 670µs 400ns |        4ms 334µs | 146µs 304ns |  1.00
 1 | { fd | is-empty }    | 33ms 325µs 304ns |      31ms 963µs | 36ms 328µs 500ns | 701µs 295ns |  8.73

→ bench -p { ls -a | is-empty } { fd | is-empty }
Benchmark 1: { ls -a | is-empty }
    3ms 757µs 124ns +/- 103µs 165ns
Benchmark 2: { fd | is-empty }
    33ms 403µs 680ns +/- 704µs 904ns

{ ls -a | is-empty } ran
    8.89 times faster than { fd | is-empty }
```

When passing a single closure, it should behave the same except that
now, the `--verbose` flag controls whether the durations of every round
is printed, and the progress indicator is in it's own flag `--progress`.

# User-Facing Changes

There are user-facing changes, but I don't think anyone is using the
output of `bench` programmatically so it hopefully won't break anything.

---------

Co-authored-by: Bahex <Bahex@users.noreply.github.com>

crates/nu-std/std/bench/mod.nu

@@ -4,52 +4,139 @@
 #
 # > **Note**
 # > `std bench --pretty` will return a `string`.
-@example "measure the performance of simple addition" { bench { 1 + 2 } -n 10 } --result {
-    mean: (4µs + 956ns)
-    std: (4µs + 831ns)
+@example "measure the performance of simple addition" { bench { 1 + 2 } } --result {
+    mean: 2308ns,
+    min: 2000ns,
+    max: 8500ns,
+    std: 895ns
+}
+@example "do 10 runs and show the time of each" { bench { 1 + 2 } -n 10 --verbose } --result {
+    mean: 3170ns,
+    min: 2200ns,
+    max: 9800ns,
+    std: 2228ns,
     times: [
-        (19µs + 402ns)
-        ( 4µs + 322ns)
-        ( 3µs + 352ns)
-        ( 2µs + 966ns)
-        ( 3µs        )
-        ( 3µs +  86ns)
-        ( 3µs +  84ns)
-        ( 3µs + 604ns)
-        ( 3µs +  98ns)
-        ( 3µs + 653ns)
+        9800ns,
+        3100ns,
+        2800ns,
+        2300ns,
+        2500ns,
+        2200ns,
+        2300ns,
+        2300ns,
+        2200ns,
+        2200ns
     ]
 }
 @example "get a pretty benchmark report" { bench { 1 + 2 } --pretty } --result "3µs 125ns +/- 2µs 408ns"
+@example "compare multiple commands" { bench { 2 + 4 } { 2 ** 4 } } --result [
+    [
+        code,
+        mean,
+        min,
+        max,
+        std,
+        ratio
+    ];
+    [
+        "{ 2 + 4 }",
+        2406ns,
+        2100ns,
+        9400ns,
+        1012ns,
+        1.02732707087959
+    ],
+    [
+        "{ 2 ** 4 }",
+        2342ns,
+        2100ns,
+        5300ns,
+        610ns,
+        1.0
+    ]
+]
+@example "compare multiple commands with pretty report" { bench { 2 + 4 } { 2 ** 4 } --pretty } --result "
+Benchmark 1: { 2 + 4 }
+    2µs 494ns +/- 1µs 105ns
+Benchmark 2: { 2 ** 4 }
+    2µs 348ns +/- 565ns
+
+{ 2 + 4 } ran
+    1 times faster than { 2 ** 4 }"
 export def main [
-    code: closure  # the piece of `nushell` code to measure the performance of
+    ...codes: closure        # the piece(s) 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>"
+    --verbose (-v)           # show individual times (has no effect if used with `--pretty`)
+    --progress (-P)          # prints the progress
+    --pretty (-p)            # shows the results in human-readable format: "<mean> +/- <stddev>"
 ]: [
     nothing -> record<mean: duration, std: duration, times: list<duration>>
+    nothing -> record<mean: duration, std: duration>
+    nothing -> table<code: string, mean: duration, std: duration, ratio: float, times: list<duration>>
+    nothing -> table<code: string, mean: duration, std: duration, ratio: float>
     nothing -> string
 ] {
+    let results = (
+        $codes | each {|code|
             let times: list<duration> = (
                 seq 1 $rounds | each {|i|
-            if $verbose { print -n $"($i) / ($rounds)\r" }
+                    if $progress { print -n $"($i) / ($rounds)\r" }
                     timeit { do $code }
                 }
             )
 
-    if $verbose { print $"($rounds) / ($rounds)" }
+            if $progress { print $"($rounds) / ($rounds)" }
 
-    let report = {
+            {
                 mean: ($times | math avg)
                 min: ($times | math min)
                 max: ($times | math max)
                 std: ($times | into int | into float | math stddev | into int | into duration)
-        times: ($times)
+            }
+            | if $verbose { merge { times: $times }} else {}
+        }
+    )
+
+    # One benchmark
+    if ($results | length) == 1 {
+        let report = $results | first
+        if $pretty {
+            return $"($report.mean) +/- ($report.std)"
+        } else {
+            return $report
+        }
     }
 
+    # Multiple benchmarks
+    let min_mean = $results | get mean | math min
+    let results = (
+        $codes
+        | each { view source $in | nu-highlight }
+        | wrap code
+        | merge $results
+        | insert ratio { $in.mean / $min_mean }
+    )
+
     if $pretty {
-        $"($report.mean) +/- ($report.std)"
+        $results
+        | enumerate
+        | each {|x|
+            let report = $x.item
+            print $"Benchmark ($x.index + 1): ($report.code)\n\t($report.mean) +/- ($report.std)"
+        }
+
+        let results = $results | sort-by ratio
+
+        print $"\n($results.0.code) ran"
+
+        $results
+        | skip
+        | each {|report|
+            print $"\t(ansi green)($report.ratio | math round -p 2)(ansi reset) times faster than ($report.code)"
+        }
+
+        ignore
     } else {
-        $report
+        $results
     }
 }