Use the empty string as a parameter to the flag being completed

Also attempt to standardize the bash and zsh implementations

Next up: tests!

bash_completions.go

@@ -280,7 +280,12 @@ __%[1]s_handle_word()
     __%[1]s_handle_word
 }
 
-__%[1]s_handle_dynamic_flag_completion()
+`, name))
+}
+
+func writeDynamicFlagCompletionFunction(buf *bytes.Buffer, dynamicFlagCompletionFunc string) {
+	buf.WriteString(fmt.Sprintf(`
+%s()
 {
     export COBRA_FLAG_COMPLETION="$1"
 
@@ -289,7 +294,7 @@ __%[1]s_handle_dynamic_flag_completion()
         return $?
     fi
 
-    if ! error_message="$($COMP_LINE > "$output")" ; then
+    if ! error_message="$("${COMP_WORDS[@]}" > "$output")" ; then
         local st="$?"
         echo "$error_message"
         return "$st"
@@ -303,7 +308,7 @@ __%[1]s_handle_dynamic_flag_completion()
     rm "$output"
 }
 
-`, name))
+`, dynamicFlagCompletionFunc))
 }
 
 func writePostscript(buf *bytes.Buffer, name string) {
@@ -553,17 +558,19 @@ func gen(buf *bytes.Buffer, cmd *Command) {
 
 // GenBashCompletion generates bash completion file and writes to the passed writer.
 func (c *Command) GenBashCompletion(w io.Writer) error {
-	visitAllFlagsWithCompletions(c, func(f *pflag.Flag) {
-		if f.Annotations == nil {
-			f.Annotations = make(map[string][]string)
-		}
-		f.Annotations[BashCompDynamic] = []string{"__" + c.Root().Name() + "_handle_dynamic_flag_completion " + f.Name}
+	dynamicFlagCompletionFunc := "__" + c.Root().Name() + "_handle_dynamic_flag_completion"
+	c.Root().visitAllFlagsWithCompletions(func(f *pflag.Flag) {
+		f.Annotations[BashCompDynamic] = []string{dynamicFlagCompletionFunc + " " + f.Name}
 	})
+
 	buf := new(bytes.Buffer)
 	writePreamble(buf, c.Name())
 	if len(c.BashCompletionFunction) > 0 {
 		buf.WriteString(c.BashCompletionFunction + "\n")
 	}
+	if c.HasDynamicCompletions() {
+		writeDynamicFlagCompletionFunction(buf, dynamicFlagCompletionFunc)
+	}
 	gen(buf, c)
 	writePostscript(buf, c.Name())
 

command.go

@@ -212,9 +212,9 @@ type Command struct {
 	// errWriter is a writer defined by the user that replaces stderr
 	errWriter io.Writer
 
-	// flagCompletions is a map of flag to a function that returns a list of values to suggest during tab completion for
-	// this flag
-	flagCompletions map[*flag.Flag]DynamicFlagCompletion
+	// dynamicFlagCompletions is a map of flag to a function that returns a list of values to suggest during tab
+	// completion for this flag
+	dynamicFlagCompletions map[*flag.Flag]DynamicFlagCompletion
 }
 
 // Context returns underlying command context. If command wasn't
@@ -907,7 +907,6 @@ func (c *Command) complete(flagName string, a []string) (err error) {
 	} else {
 		c.Flags().StringVar(&currentCompletionValue, flagName, "", "")
 	}
-	c.Flag(flagName).NoOptDefVal = "_hack_"
 
 	err = c.ParseFlags(a)
 	if err != nil {
@@ -917,10 +916,10 @@ func (c *Command) complete(flagName string, a []string) (err error) {
 	c.preRun()
 
 	currentCommand := c
-	completionFunc := currentCommand.flagCompletions[flagToComplete]
+	completionFunc := currentCommand.dynamicFlagCompletions[flagToComplete]
 	for completionFunc == nil && currentCommand.HasParent() {
 		currentCommand = currentCommand.Parent()
-		completionFunc = currentCommand.flagCompletions[flagToComplete]
+		completionFunc = currentCommand.dynamicFlagCompletions[flagToComplete]
 	}
 	if completionFunc == nil {
 		return fmt.Errorf("%s does not have completions enabled", flagName)
@@ -958,6 +957,7 @@ func (c *Command) complete(flagName string, a []string) (err error) {
 	}
 
 	for _, v := range values {
+		c.OutOrStdout()
 		fmt.Print(v + "\x00")
 	}
 
@@ -1741,15 +1741,26 @@ func (c *Command) updateParentsPflags() {
 	})
 }
 
-func visitAllFlagsWithCompletions(c *Command, fn func(*flag.Flag)) {
+func (c *Command) HasDynamicCompletions() bool {
+	hasCompletions := false
+	c.visitAllFlagsWithCompletions(func(*flag.Flag) { hasCompletions = true })
+	return hasCompletions
+}
+
+// visitAllFlagsWithCompletions recursively visits all flags and persistent flags that have dynamic completions enabled.
+// Initializes the flag's Annotations map if nil before calling fn
+func (c Command) visitAllFlagsWithCompletions(fn func(*flag.Flag)) {
 	filterFunc := func(f *flag.Flag) {
-		if _, ok := c.flagCompletions[f]; ok {
+		if _, ok := c.dynamicFlagCompletions[f]; ok {
+			if f.Annotations == nil {
+				f.Annotations = make(map[string][]string)
+			}
 			fn(f)
 		}
 	}
 	c.Flags().VisitAll(filterFunc)
 	c.PersistentFlags().VisitAll(filterFunc)
 	for _, sc := range c.Commands() {
-		visitAllFlagsWithCompletions(sc, fn)
+		sc.visitAllFlagsWithCompletions(fn)
 	}
 }

shell_completions.go

@@ -103,10 +103,10 @@ func (c *Command) MarkDynamicFlagCompletion(name string, completion DynamicFlagC
 		return fmt.Errorf("%s takes no parameters", name)
 	}
 
-	if c.flagCompletions == nil {
-		c.flagCompletions = make(map[*pflag.Flag]DynamicFlagCompletion)
+	if c.dynamicFlagCompletions == nil {
+		c.dynamicFlagCompletions = make(map[*pflag.Flag]DynamicFlagCompletion)
 	}
-	c.flagCompletions[flag] = completion
+	c.dynamicFlagCompletions[flag] = completion
 
 	return nil
 }

zsh_completions.go

@@ -27,7 +27,6 @@ var (
 		"genFlagEntryForZshArguments":         zshCompGenFlagEntryForArguments,
 		"extractArgsCompletions":              zshCompExtractArgumentCompletionHintsForRendering,
 		"genZshFlagDynamicCompletionFuncName": zshCompGenDynamicFlagCompletionFuncName,
-		"hasDynamicCompletions":               zshCompHasDynamicCompletions,
 	}
 	zshCompletionText = `
 {{/* should accept Command (that contains subcommands) as parameter */}}
@@ -35,6 +34,9 @@ var (
 {{ $cmdPath := genZshFuncName .}}
 function {{$cmdPath}} {
   local -a commands
+{{/* If we are at the root, save a copy of the $words array as it contains the full command, including any empty
+     strings and other parameters */}}
+{{ if (not .HasParent) and .HasDynamicCompletions }}  full_command=("${(@)words}"){{- end}}
 
   _arguments -C \{{- range extractFlags .}}
     {{genFlagEntryForZshArguments .}} \{{- end}}
@@ -82,7 +84,7 @@ function {{genZshFuncName .}} {
 {{define "Main" -}}
 #compdef _{{.Name}} {{.Name}}
 
-{{if hasDynamicCompletions . -}}
+{{if .HasDynamicCompletions -}}
 function {{genZshFlagDynamicCompletionFuncName .}} {
   export COBRA_FLAG_COMPLETION="$1"
 
@@ -91,7 +93,7 @@ function {{genZshFlagDynamicCompletionFuncName .}} {
     return $?
   fi
 
-  if ! error_message="$($tokens 2>&1 > "$output")" ; then
+  if ! error_message="$("${(@)full_command}" 2>&1 > "$output")" ; then
     local st="$?"
     _message "Exception occurred during completion: $error_message"
     return "$st"
@@ -102,7 +104,11 @@ function {{genZshFlagDynamicCompletionFuncName .}} {
     args+="$line"
   done < "$output"
 
-  _values "$1" $args
+  if [[ $#args -gt 0 ]] ; then
+    _values "$1" "${(@)args}"
+  else
+    _message "No matching completion for $descr: $opt_args"
+  fi
 
   unset COBRA_FLAG_COMPLETION
   rm "$output"
@@ -141,12 +147,11 @@ func (c *Command) GenZshCompletionFile(filename string) error {
 // writer. The completion always run on the root command regardless of the
 // command it was called from.
 func (c *Command) GenZshCompletion(w io.Writer) error {
-	visitAllFlagsWithCompletions(c, func(f *pflag.Flag) {
-		if f.Annotations == nil {
-			f.Annotations = make(map[string][]string)
-		}
-		f.Annotations[zshCompDynamicCompletion] = []string{zshCompGenDynamicFlagCompletionFuncName(c)}
+	dynamicFlagCompletionFuncName := zshCompGenDynamicFlagCompletionFuncName(c.Root())
+	c.Root().visitAllFlagsWithCompletions(func(f *pflag.Flag) {
+		f.Annotations[zshCompDynamicCompletion] = []string{dynamicFlagCompletionFuncName + " " + f.Name}
 	})
+
 	tmpl, err := template.New("Main").Funcs(zshCompFuncMap).Parse(zshCompletionText)
 	if err != nil {
 		return fmt.Errorf("error creating zsh completion template: %v", err)
@@ -285,10 +290,6 @@ func zshCompGenFuncName(c *Command) string {
 	return "_" + c.Name()
 }
 
-func zshCompGenDynamicFlagCompletionFuncName(c *Command) string {
-	return "_" + c.Root().Name() + "-flag-completion"
-}
-
 func zshCompExtractFlag(c *Command) []*pflag.Flag {
 	var flags []*pflag.Flag
 	c.LocalFlags().VisitAll(func(f *pflag.Flag) {
@@ -360,7 +361,7 @@ func zshCompGenFlagEntryExtras(f *pflag.Flag) string {
 				extras = extras + fmt.Sprintf(` -g "%s"`, pattern)
 			}
 		case zshCompDynamicCompletion:
-			extras += fmt.Sprintf(":{%s %s}", values[0], f.Name)
+			extras += fmt.Sprintf(":{%s}", values[0])
 		}
 	}
 
@@ -376,14 +377,6 @@ func zshCompQuoteFlagDescription(s string) string {
 	return strings.Replace(s, "'", `'\''`, -1)
 }
 
-func zshCompHasDynamicCompletions(c *Command) bool {
-	if len(c.flagCompletions) > 0 {
-		return true
-	}
-	for _, subcommand := range c.Commands() {
-		if zshCompHasDynamicCompletions(subcommand) {
-			return true
-		}
-	}
-	return false
+func zshCompGenDynamicFlagCompletionFuncName(c *Command) string {
+	return "_" + c.Root().Name() + "-handle-dynamic-flag-completion"
 }