Add support for zsh to helm completion

Updated the 'helm completion' command to take in the shell
as a parameter. Currently acceptable options are 'bash' and
'zsh'. Also fixed the completions to work with zsh in a manner
similar to what kubectl does.

Also updated the docs to reflect this change.

Closes #2201

cmd/helm/completion.go

@@ -16,32 +16,214 @@ limitations under the License.
 package main
 
 import (
+	"bytes"
+	"fmt"
 	"io"
 
 	"github.com/spf13/cobra"
 )
 
 const completionDesc = `
-Generate bash autocompletions script for Helm.
+Generate autocompletions script for Helm for the specified shell (bash or zsh).
 
-This command can generate shell autocompletions.
+This command can generate shell autocompletions. e.g.
 
-	$ helm completion
+	$ helm completion bash
 
 Can be sourced as such
 
-	$ source <(helm completion)
+	$ source <(helm completion bash)
 `
 
+var (
+	completion_shells = map[string]func(out io.Writer, cmd *cobra.Command) error{
+		"bash": runCompletionBash,
+		"zsh":  runCompletionZsh,
+	}
+)
+
 func newCompletionCmd(out io.Writer) *cobra.Command {
+	shells := []string{}
+	for s := range completion_shells {
+		shells = append(shells, s)
+	}
+
 	cmd := &cobra.Command{
-		Use:    "completion",
-		Short:  "Generate bash autocompletions script",
-		Long:   completionDesc,
-		Hidden: false,
-		RunE: func(cmd *cobra.Command, _ []string) error {
-			return cmd.Root().GenBashCompletion(out)
+		Use:   "completion SHELL",
+		Short: "Generate autocompletions script for the specified shell (bash or zsh)",
+		Long:  completionDesc,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return RunCompletion(out, cmd, args)
 		},
+		ValidArgs: shells,
 	}
+
 	return cmd
 }
+
+func RunCompletion(out io.Writer, cmd *cobra.Command, args []string) error {
+	if len(args) == 0 {
+		return fmt.Errorf("Shell not specified.")
+	}
+	if len(args) > 1 {
+		return fmt.Errorf("Too many arguments. Expected only the shell type.")
+	}
+	run, found := completion_shells[args[0]]
+	if !found {
+		return fmt.Errorf("Unsupported shell type %q.", args[0])
+	}
+
+	return run(out, cmd)
+}
+
+func runCompletionBash(out io.Writer, cmd *cobra.Command) error {
+	return cmd.Root().GenBashCompletion(out)
+}
+
+func runCompletionZsh(out io.Writer, cmd *cobra.Command) error {
+	zsh_initialization := `
+__helm_bash_source() {
+	alias shopt=':'
+	alias _expand=_bash_expand
+	alias _complete=_bash_comp
+	emulate -L sh
+	setopt kshglob noshglob braceexpand
+	source "$@"
+}
+__helm_type() {
+	# -t is not supported by zsh
+	if [ "$1" == "-t" ]; then
+		shift
+		# fake Bash 4 to disable "complete -o nospace". Instead
+		# "compopt +-o nospace" is used in the code to toggle trailing
+		# spaces. We don't support that, but leave trailing spaces on
+		# all the time
+		if [ "$1" = "__helm_compopt" ]; then
+			echo builtin
+			return 0
+		fi
+	fi
+	type "$@"
+}
+__helm_compgen() {
+	local completions w
+	completions=( $(compgen "$@") ) || return $?
+	# filter by given word as prefix
+	while [[ "$1" = -* && "$1" != -- ]]; do
+		shift
+		shift
+	done
+	if [[ "$1" == -- ]]; then
+		shift
+	fi
+	for w in "${completions[@]}"; do
+		if [[ "${w}" = "$1"* ]]; then
+			echo "${w}"
+		fi
+	done
+}
+__helm_compopt() {
+	true # don't do anything. Not supported by bashcompinit in zsh
+}
+__helm_declare() {
+	if [ "$1" == "-F" ]; then
+		whence -w "$@"
+	else
+		builtin declare "$@"
+	fi
+}
+__helm_ltrim_colon_completions()
+{
+	if [[ "$1" == *:* && "$COMP_WORDBREAKS" == *:* ]]; then
+		# Remove colon-word prefix from COMPREPLY items
+		local colon_word=${1%${1##*:}}
+		local i=${#COMPREPLY[*]}
+		while [[ $((--i)) -ge 0 ]]; do
+			COMPREPLY[$i]=${COMPREPLY[$i]#"$colon_word"}
+		done
+	fi
+}
+__helm_get_comp_words_by_ref() {
+	cur="${COMP_WORDS[COMP_CWORD]}"
+	prev="${COMP_WORDS[${COMP_CWORD}-1]}"
+	words=("${COMP_WORDS[@]}")
+	cword=("${COMP_CWORD[@]}")
+}
+__helm_filedir() {
+	local RET OLD_IFS w qw
+	__debug "_filedir $@ cur=$cur"
+	if [[ "$1" = \~* ]]; then
+		# somehow does not work. Maybe, zsh does not call this at all
+		eval echo "$1"
+		return 0
+	fi
+	OLD_IFS="$IFS"
+	IFS=$'\n'
+	if [ "$1" = "-d" ]; then
+		shift
+		RET=( $(compgen -d) )
+	else
+		RET=( $(compgen -f) )
+	fi
+	IFS="$OLD_IFS"
+	IFS="," __debug "RET=${RET[@]} len=${#RET[@]}"
+	for w in ${RET[@]}; do
+		if [[ ! "${w}" = "${cur}"* ]]; then
+			continue
+		fi
+		if eval "[[ \"\${w}\" = *.$1 || -d \"\${w}\" ]]"; then
+			qw="$(__helm_quote "${w}")"
+			if [ -d "${w}" ]; then
+				COMPREPLY+=("${qw}/")
+			else
+				COMPREPLY+=("${qw}")
+			fi
+		fi
+	done
+}
+__helm_quote() {
+	if [[ $1 == \'* || $1 == \"* ]]; then
+		# Leave out first character
+		printf %q "${1:1}"
+	else
+		printf %q "$1"
+	fi
+}
+autoload -U +X bashcompinit && bashcompinit
+# use word boundary patterns for BSD or GNU sed
+LWORD='[[:<:]]'
+RWORD='[[:>:]]'
+if sed --help 2>&1 | grep -q GNU; then
+	LWORD='\<'
+	RWORD='\>'
+fi
+__helm_convert_bash_to_zsh() {
+	sed \
+	-e 's/declare -F/whence -w/' \
+	-e 's/_get_comp_words_by_ref "\$@"/_get_comp_words_by_ref "\$*"/' \
+	-e 's/local \([a-zA-Z0-9_]*\)=/local \1; \1=/' \
+	-e 's/flags+=("\(--.*\)=")/flags+=("\1"); two_word_flags+=("\1")/' \
+	-e 's/must_have_one_flag+=("\(--.*\)=")/must_have_one_flag+=("\1")/' \
+	-e "s/${LWORD}_filedir${RWORD}/__helm_filedir/g" \
+	-e "s/${LWORD}_get_comp_words_by_ref${RWORD}/__helm_get_comp_words_by_ref/g" \
+	-e "s/${LWORD}__ltrim_colon_completions${RWORD}/__helm_ltrim_colon_completions/g" \
+	-e "s/${LWORD}compgen${RWORD}/__helm_compgen/g" \
+	-e "s/${LWORD}compopt${RWORD}/__helm_compopt/g" \
+	-e "s/${LWORD}declare${RWORD}/__helm_declare/g" \
+	-e "s/\\\$(type${RWORD}/\$(__helm_type/g" \
+	<<'BASH_COMPLETION_EOF'
+`
+	out.Write([]byte(zsh_initialization))
+
+	buf := new(bytes.Buffer)
+	cmd.Root().GenBashCompletion(buf)
+	out.Write(buf.Bytes())
+
+	zsh_tail := `
+BASH_COMPLETION_EOF
+}
+__helm_bash_source <(__helm_convert_bash_to_zsh)
+`
+	out.Write([]byte(zsh_tail))
+	return nil
+}

docs/helm/helm.md

@@ -40,7 +40,7 @@ Environment:
 ```
 
 ### SEE ALSO
-* [helm completion](helm_completion.md)	 - Generate bash autocompletions script
+* [helm completion](helm_completion.md)	 - Generate autocompletions script for the specified shell (bash or zsh)
 * [helm create](helm_create.md)	 - create a new chart with the given name
 * [helm delete](helm_delete.md)	 - given a release name, delete the release from Kubernetes
 * [helm dependency](helm_dependency.md)	 - manage a chart's dependencies

docs/helm/helm_completion.md

 ## helm completion
 
-Generate bash autocompletions script
+Generate autocompletions script for the specified shell (bash or zsh)
 
 ### Synopsis
 
 
 
-Generate bash autocompletions script for Helm.
+Generate autocompletions script for Helm for the specified shell (bash or zsh).
 
-This command can generate shell autocompletions.
+This command can generate shell autocompletions. e.g.
 
-	$ helm completion
+	$ helm completion bash
 
 Can be sourced as such
 
-	$ source <(helm completion)
+	$ source <(helm completion bash)
 
 
 ```
-helm completion
+helm completion SHELL
 ```
 
 ### Options inherited from parent commands

docs/man/man1/helm_completion.1

@@ -5,26 +5,26 @@
 
 .SH NAME
 .PP
-helm\-completion \- Generate bash autocompletions script
+helm\-completion \- Generate autocompletions script for the specified shell (bash or zsh)
 
 
 .SH SYNOPSIS
 .PP
-\fBhelm completion\fP
+\fBhelm completion SHELL\fP
 
 
 .SH DESCRIPTION
 .PP
-Generate bash autocompletions script for Helm.
+Generate autocompletions script for Helm for the specified shell (bash or zsh).
 
 .PP
-This command can generate shell autocompletions.
+This command can generate shell autocompletions. e.g.
 
 .PP
 .RS
 
 .nf
-$ helm completion
+$ helm completion bash
 
 .fi
 .RE
@@ -36,7 +36,7 @@ Can be sourced as such
 .RS
 
 .nf
-$ source <(helm completion)
+$ source <(helm completion bash)
 
 .fi
 .RE

scripts/completions.bash

@@ -242,6 +242,8 @@ _helm_completion()
 
     must_have_one_flag=()
     must_have_one_noun=()
+    must_have_one_noun+=("bash")
+    must_have_one_noun+=("zsh")
     noun_aliases=()
 }