feat: add getters for flag completions (#1943)

completions.go

@@ -145,6 +145,25 @@ func (c *Command) RegisterFlagCompletionFunc(flagName string, f func(cmd *Comman
 	return nil
 }
 
+// GetFlagCompletion returns the completion function for the given flag, if available.
+func GetFlagCompletion(flag *pflag.Flag) (func(cmd *Command, args []string, toComplete string) ([]string, ShellCompDirective), bool) {
+	flagCompletionMutex.RLock()
+	defer flagCompletionMutex.RUnlock()
+
+	completionFunc, exists := flagCompletionFunctions[flag]
+	return completionFunc, exists
+}
+
+// GetFlagCompletionByName returns the completion function for the given flag in the command by name, if available.
+func (c *Command) GetFlagCompletionByName(flagName string) (func(cmd *Command, args []string, toComplete string) ([]string, ShellCompDirective), bool) {
+	flag := c.Flags().Lookup(flagName)
+	if flag == nil {
+		return nil, false
+	}
+
+	return GetFlagCompletion(flag)
+}
+
 // Returns a string listing the different directive enabled in the specified parameter
 func (d ShellCompDirective) string() string {
 	var directives []string