Completion support for Nushell

README.md

@@ -25,7 +25,7 @@ Cobra provides:
 * Automatic help generation for commands and flags
 * Grouping help for subcommands
 * Automatic help flag recognition of `-h`, `--help`, etc.
-* Automatically generated shell autocomplete for your application (bash, zsh, fish, powershell)
+* Automatically generated shell autocomplete for your application (bash, zsh, fish, powershell, nushell)
 * Automatically generated man pages for your application
 * Command aliases so you can change things without breaking them
 * The flexibility to define your own help, usage, etc.

completions.go

@@ -836,14 +836,43 @@ to your powershell profile.
 				return cmd.Root().GenPowerShellCompletion(out)
 			}
 			return cmd.Root().GenPowerShellCompletionWithDesc(out)
-
 		},
 	}
 	if haveNoDescFlag {
 		powershell.Flags().BoolVar(&noDesc, compCmdNoDescFlagName, compCmdNoDescFlagDefault, compCmdNoDescFlagDesc)
 	}
 
-	completionCmd.AddCommand(bash, zsh, fish, powershell)
+	nushell := &Command{
+		Use:   "nushell",
+		Short: fmt.Sprintf(shortDesc, "nushell"),
+		Long: fmt.Sprintf(`Generate the autocompletion script for nushell.
+
+To configure the Nushell cobra external completer for the first time:
+  # 1. Edit the nushell config file:
+  > config nu
+  # 2. Copy the completer to at the end of the file.
+  # 3. Add a section like the following below at the end of the file:
+    $env.config.completions.external = {
+        enable: true
+        max_results: 100
+        completer: $cobra_completer
+    }
+
+NOTE: This completer will work for all cobra based commands.
+More information can be found in the External Completions (https://www.nushell.sh/book/custom_completions.html#custom-descriptions) section of the Nushell book.
+Information on setting up more than one external completer can be found in the Multiple completer (https://www.nushell.sh/cookbook/external_completers.html#multiple-completer) section of the Nushell cookbook.
+`),
+		Args:              NoArgs,
+		ValidArgsFunction: NoFileCompletions,
+		RunE: func(cmd *Command, args []string) error {
+			return cmd.Root().GenNushellCompletion(out, !noDesc)
+		},
+	}
+	if haveNoDescFlag {
+		nushell.Flags().BoolVar(&noDesc, compCmdNoDescFlagName, compCmdNoDescFlagDefault, compCmdNoDescFlagDesc)
+	}
+
+	completionCmd.AddCommand(bash, zsh, fish, powershell, nushell)
 }
 
 func findFlag(cmd *Command, name string) *pflag.Flag {
@@ -876,7 +905,7 @@ func CompDebug(msg string, printToStdErr bool) {
 	// variable BASH_COMP_DEBUG_FILE to the path of some file to be used.
 	if path := os.Getenv("BASH_COMP_DEBUG_FILE"); path != "" {
 		f, err := os.OpenFile(path,
-			os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+			os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
 		if err == nil {
 			defer f.Close()
 			WriteStringAndCheck(f, msg)

completions_test.go

@@ -2577,6 +2577,7 @@ func TestCompleteCompletion(t *testing.T) {
 	expected := strings.Join([]string{
 		"bash",
 		"fish",
+		"nushell",
 		"powershell",
 		"zsh",
 		":4",

nushell_completions.go

@@ -0,0 +1,128 @@
+// Copyright 2013-2022 The Cobra Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cobra
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+)
+
+func (c *Command) GenNushellCompletion(w io.Writer, includeDesc bool) error {
+	buf := new(bytes.Buffer)
+	WriteStringAndCheck(buf, "# nushell completion -*- shell-script -*- \n")
+	WriteStringAndCheck(buf, fmt.Sprintf(`
+let cobra_completer = {|spans|
+    let ShellCompDirectiveError = %[1]d
+    let ShellCompDirectiveNoSpace = %[2]d
+    let ShellCompDirectiveNoFileComp = %[3]d
+    let ShellCompDirectiveFilterFileExt = %[4]d
+    let ShellCompDirectiveFilterDirs = %[5]d
+    let ShellCompDirectiveKeepOrder = %[6]d
+
+    let cmd = $spans | first 
+    let rest = $spans | skip
+
+    def exec_complete [
+        spans: list<string>
+    ] {
+        # This will catch the stderr message related to the directive and any other errors,
+        # such as the command not being a cobra based command
+        let result = do --ignore-errors { COBRA_ACTIVE_HELP=0 run-external $cmd "__complete" ...$spans | complete }
+
+        if $result != null and $result.exit_code == 0 {
+            let completions = $result.stdout | lines
+
+            # the directive is the last line
+            let directive = do -i { $completions | last | str replace ':' '' | into int }
+
+            let completions = $completions | drop | each { |it| 
+                # the first word is the command, the rest is the description
+                let words = $it | split row -r '\s{1}'
+
+                # If the last span contains a hypen and equals, attach it to the name
+                let last_span = $spans | last
+                let words = if ($last_span =~ '^-') and ($last_span =~ '=$') {
+                    $words | each {|it| $"($last_span)($it)" }
+                } else {
+                    $words
+                }
+
+                {value: ($words | first | str trim), description: ($words | skip | str join ' ')}
+            }
+
+            {completions: $completions, directive: $directive}
+        } else {
+            {completions: [], directive: -1}
+        }
+    }
+
+    if (not ($rest | is-empty)) {
+        let result = exec_complete $rest
+        let completions = $result.completions
+        let directive = $result.directive
+
+        # Add space at the end of each completion
+        let completions = if $directive != $ShellCompDirectiveNoSpace {
+            $completions | each {|it| {value: $"($it.value) ", description: $it.description}}
+        } else {
+            $completions
+        }
+
+        # Cobra returns a list of completions that are supported with this directive
+        # There is no way to currently support this in a nushell external completer
+        let completions = if $directive == $ShellCompDirectiveFilterFileExt {
+            []
+        } else {
+            $completions
+        }
+
+        if $directive == $ShellCompDirectiveNoFileComp {
+            # Allow empty results as this will stop file completion
+            $completions
+        } else if ($completions | is-empty)  or  $directive == $ShellCompDirectiveError {
+            # Not returning null causes file completions to break
+            # Return null if there are no completions or ShellCompDirectiveError
+             null
+          } else {
+            $completions
+        }
+
+        if ($completions | is-empty) {
+            null
+        } else {
+            $completions
+        }
+    } else {
+        null
+    }
+}
+`, ShellCompDirectiveError, ShellCompDirectiveNoSpace, ShellCompDirectiveNoFileComp,
+		ShellCompDirectiveFilterFileExt, ShellCompDirectiveFilterDirs, ShellCompDirectiveKeepOrder))
+
+	_, err := buf.WriteTo(w)
+	return err
+}
+
+func (c *Command) GenNushellCompletionFile(filename string, includeDesc bool) error {
+	outFile, err := os.Create(filename)
+	if err != nil {
+		return err
+	}
+	defer outFile.Close()
+
+	return c.GenNushellCompletion(outFile, includeDesc)
+}

nushell_completions_test.go

@@ -0,0 +1,98 @@
+// Copyright 2013-2022 The Cobra Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cobra
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"log"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestGenNushellCompletion(t *testing.T) {
+	rootCmd := &Command{Use: "kubectl", Run: emptyRun}
+	rootCmd.PersistentFlags().String("server", "s", "The address and port of the Kubernetes API server")
+	rootCmd.PersistentFlags().BoolP("skip-headers", "", false, "The address and port of the Kubernetes API serverIf true, avoid header prefixes in the log messages")
+	getCmd := &Command{
+		Use:        "get",
+		Short:      "Display one or many resources",
+		ArgAliases: []string{"pods", "nodes", "services", "replicationcontrollers", "po", "no", "svc", "rc"},
+		ValidArgs:  []string{"pod", "node", "service", "replicationcontroller"},
+		Run:        emptyRun,
+	}
+	rootCmd.AddCommand(getCmd)
+
+	buf := new(bytes.Buffer)
+	assertNoErr(t, rootCmd.GenNushellCompletion(buf, true))
+}
+
+func TestGenNushellCompletionFile(t *testing.T) {
+	tmpFile, err := os.CreateTemp("", "cobra-test")
+	if err != nil {
+		log.Fatal(err.Error())
+	}
+
+	defer os.RemoveAll(tmpFile.Name())
+
+	rootCmd := &Command{Use: "root", Args: NoArgs, Run: emptyRun}
+	child := &Command{
+		Use:               "child",
+		ValidArgsFunction: validArgsFunc,
+		Run:               emptyRun,
+	}
+	rootCmd.AddCommand(child)
+
+	assertNoErr(t, rootCmd.GenNushellCompletionFile(tmpFile.Name(), true))
+}
+
+func TestFailGenNushellCompletionFile(t *testing.T) {
+	tmpDir, err := os.MkdirTemp("", "cobra-test")
+	if err != nil {
+		t.Fatal(err.Error())
+	}
+
+	defer os.RemoveAll(tmpDir)
+
+	f, _ := os.OpenFile(filepath.Join(tmpDir, "test"), os.O_CREATE, 0400)
+	defer f.Close()
+
+	rootCmd := &Command{Use: "root", Args: NoArgs, Run: emptyRun}
+	child := &Command{
+		Use:               "child",
+		ValidArgsFunction: validArgsFunc,
+		Run:               emptyRun,
+	}
+	rootCmd.AddCommand(child)
+
+	got := rootCmd.GenFishCompletionFile(f.Name(), false)
+	if !errors.Is(got, os.ErrPermission) {
+		t.Errorf("got: %s, want: %s", got.Error(), os.ErrPermission.Error())
+	}
+}
+
+func TestNushellCompletionNoActiveHelp(t *testing.T) {
+	c := &Command{Use: "c", Run: emptyRun}
+
+	buf := new(bytes.Buffer)
+	assertNoErr(t, c.GenNushellCompletion(buf, true))
+	output := buf.String()
+
+	// check that active help is being disabled
+	activeHelpVar := activeHelpGlobalEnvVar
+	check(t, output, fmt.Sprintf("%s=0", activeHelpVar))
+}

site/content/completions/_index.md

@@ -6,6 +6,7 @@ The currently supported shells are:
 - Zsh
 - fish
 - PowerShell
+- Nushell
 
 Cobra will automatically provide your program with a fully functional `completion` command,
 similarly to how it provides the `help` command.
@@ -28,7 +29,7 @@ and then modifying the generated `cmd/completion.go` file to look something like
 
 ```go
 var completionCmd = &cobra.Command{
-	Use:   "completion [bash|zsh|fish|powershell]",
+	Use:   "completion [bash|zsh|fish|powershell|nushell]",
 	Short: "Generate completion script",
 	Long: fmt.Sprintf(`To load completions:
 
@@ -68,9 +69,27 @@ PowerShell:
   # To load completions for every new session, run:
   PS> %[1]s completion powershell > %[1]s.ps1
   # and source this file from your PowerShell profile.
+
+Nushell:
+
+  # To configure the Nushell cobra external completer for the first time:
+  # 1. Edit the nushell config file:
+  > config nu
+  # 2. Copy the completer to at the end of the file.
+  # 3. Add a section like the following below at the end of the file:
+    $env.config.completions.external = {
+        enable: true
+        max_results: 100
+        completer: $cobra_completer
+    }
+
+NOTE: This completer will work for all cobra based commands. 
+More information can be found in the External Completions (https://www.nushell.sh/book/custom_completions.html#custom-descriptions) section of the Nushell book. 
+Information on setting up more than one external completer can be found in the Multiple completer (https://www.nushell.sh/cookbook/external_completers.html#multiple-completer) section of the Nushell cookbook.
+
 `,cmd.Root().Name()),
 	DisableFlagsInUseLine: true,
-	ValidArgs:             []string{"bash", "zsh", "fish", "powershell"},
+	ValidArgs:             []string{"bash", "zsh", "fish", "powershell", "nushell"},
 	Args:                  cobra.MatchAll(cobra.ExactArgs(1), cobra.OnlyValidArgs),
 	Run: func(cmd *cobra.Command, args []string) {
 		switch args[0] {
@@ -82,6 +101,8 @@ PowerShell:
 			cmd.Root().GenFishCompletion(os.Stdout, true)
 		case "powershell":
 			cmd.Root().GenPowerShellCompletionWithDesc(os.Stdout)
+		case "nushell":
+			cmd.Root().GenNushellCompletion(os.Stdout, true)
 		}
 	},
 }

site/content/completions/nushell_completions.md

@@ -0,0 +1,3 @@
+## Generating Nushell Completions For Your cobra.Command
+
+Please refer to [Shell Completions](_index.md#nushell-completions) for details.