spf13--cobra/custom_completions.go

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package cobra
import (
"errors"
"fmt"
"os"
"strings"
"github.com/spf13/pflag"
)
// ShellCompRequestCmd is the name of the hidden command that is used to request
// completion results from the program. It is used by the shell completion script.
const ShellCompRequestCmd = "__complete"
// Global map of flag completion functions.
var flagCompletionFunctions = map[*pflag.Flag]func(cmd *Command, args []string, toComplete string) ([]string, ShellCompDirective){}
// ShellCompDirective is a bit map representing the different behaviors the shell
// can be instructed to have once completions have been provided.
type ShellCompDirective int
const (
// ShellCompDirectiveError indicates an error occurred and completions should be ignored.
ShellCompDirectiveError ShellCompDirective = 1 << iota
// ShellCompDirectiveNoSpace indicates that the shell should not add a space
// after the completion even if there is a single completion provided.
ShellCompDirectiveNoSpace
// ShellCompDirectiveNoFileComp indicates that the shell should not provide
// file completion even when no completion is provided.
// This currently does not work for zsh or bash < 4
ShellCompDirectiveNoFileComp
// ShellCompDirectiveDefault indicates to let the shell perform its default
// behavior after completions have been provided.
ShellCompDirectiveDefault ShellCompDirective = 0
)
// RegisterFlagCompletionFunc should be called to register a function to provide completion for a flag.
func (c *Command) RegisterFlagCompletionFunc(flagName string, f func(cmd *Command, args []string, toComplete string) ([]string, ShellCompDirective)) error {
flag := c.Flag(flagName)
if flag == nil {
return fmt.Errorf("RegisterFlagCompletionFunc: flag '%s' does not exist", flagName)
}
if _, exists := flagCompletionFunctions[flag]; exists {
return fmt.Errorf("RegisterFlagCompletionFunc: flag '%s' already registered", flagName)
}
flagCompletionFunctions[flag] = f
return nil
}
// Returns a string listing the different directive enabled in the specified parameter
func (d ShellCompDirective) string() string {
var directives []string
if d&ShellCompDirectiveError != 0 {
directives = append(directives, "ShellCompDirectiveError")
}
if d&ShellCompDirectiveNoSpace != 0 {
directives = append(directives, "ShellCompDirectiveNoSpace")
}
if d&ShellCompDirectiveNoFileComp != 0 {
directives = append(directives, "ShellCompDirectiveNoFileComp")
}
if len(directives) == 0 {
directives = append(directives, "ShellCompDirectiveDefault")
}
if d > ShellCompDirectiveError+ShellCompDirectiveNoSpace+ShellCompDirectiveNoFileComp {
return fmt.Sprintf("ERROR: unexpected ShellCompDirective value: %d", d)
}
return strings.Join(directives, ", ")
}
// Adds a special hidden command that can be used to request custom completions.
func (c *Command) initCompleteCmd(args []string) {
completeCmd := &Command{
Use: fmt.Sprintf("%s [command-line]", ShellCompRequestCmd),
DisableFlagsInUseLine: true,
Hidden: true,
DisableFlagParsing: true,
Args: MinimumNArgs(1),
Short: "Request shell completion choices for the specified command-line",
Long: fmt.Sprintf("%[2]s is a special command that is used by the shell completion logic\n%[1]s",
"to request completion choices for the specified command-line.", ShellCompRequestCmd),
Run: func(cmd *Command, args []string) {
finalCmd, completions, directive, err := cmd.getCompletions(args)
if err != nil {
CompErrorln(err.Error())
// Keep going for multiple reasons:
// 1- There could be some valid completions even though there was an error
// 2- Even without completions, we need to print the directive
}
for _, comp := range completions {
// Print each possible completion to stdout for the completion script to consume.
fmt.Fprintln(finalCmd.OutOrStdout(), comp)
}
if directive > ShellCompDirectiveError+ShellCompDirectiveNoSpace+ShellCompDirectiveNoFileComp {
directive = ShellCompDirectiveDefault
}
// As the last printout, print the completion directive for the completion script to parse.
// The directive integer must be that last character following a single colon (:).
// The completion script expects :<directive>
fmt.Fprintf(finalCmd.OutOrStdout(), ":%d\n", directive)
// Print some helpful info to stderr for the user to understand.
// Output from stderr must be ignored by the completion script.
fmt.Fprintf(finalCmd.ErrOrStderr(), "Completion ended with directive: %s\n", directive.string())
},
}
c.AddCommand(completeCmd)
subCmd, _, err := c.Find(args)
if err != nil || subCmd.Name() != ShellCompRequestCmd {
// Only create this special command if it is actually being called.
// This reduces possible side-effects of creating such a command;
// for example, having this command would cause problems to a
// cobra program that only consists of the root command, since this
// command would cause the root command to suddenly have a subcommand.
c.RemoveCommand(completeCmd)
}
}
func (c *Command) getCompletions(args []string) (*Command, []string, ShellCompDirective, error) {
var completions []string
// The last argument, which is not completely typed by the user,
// should not be part of the list of arguments
toComplete := args[len(args)-1]
trimmedArgs := args[:len(args)-1]
// Find the real command for which completion must be performed
finalCmd, finalArgs, err := c.Root().Find(trimmedArgs)
if err != nil {
// Unable to find the real command. E.g., <program> someInvalidCmd <TAB>
return c, completions, ShellCompDirectiveDefault, fmt.Errorf("Unable to find a command for arguments: %v", trimmedArgs)
}
var flag *pflag.Flag
if !finalCmd.DisableFlagParsing {
// We only do flag completion if we are allowed to parse flags
// This is important for commands which have requested to do their own flag completion.
flag, finalArgs, toComplete, err = checkIfFlagCompletion(finalCmd, finalArgs, toComplete)
if err != nil {
// Error while attempting to parse flags
return finalCmd, completions, ShellCompDirectiveDefault, err
}
}
// Parse the flags and extract the arguments to prepare for calling the completion function
if err = finalCmd.ParseFlags(finalArgs); err != nil {
return finalCmd, completions, ShellCompDirectiveDefault, fmt.Errorf("Error while parsing flags from args %v: %s", finalArgs, err.Error())
}
// We only remove the flags from the arguments if DisableFlagParsing is not set.
// This is important for commands which have requested to do their own flag completion.
if !finalCmd.DisableFlagParsing {
finalArgs = finalCmd.Flags().Args()
}
// Find the completion function for the flag or command
var completionFn func(cmd *Command, args []string, toComplete string) ([]string, ShellCompDirective)
if flag != nil {
completionFn = flagCompletionFunctions[flag]
} else {
completionFn = finalCmd.ValidArgsFunction
}
if completionFn == nil {
// Go custom completion not supported/needed for this flag or command
return finalCmd, completions, ShellCompDirectiveDefault, nil
}
// Call the registered completion function to get the completions
comps, directive := completionFn(finalCmd, finalArgs, toComplete)
completions = append(completions, comps...)
return finalCmd, completions, directive, nil
}
func checkIfFlagCompletion(finalCmd *Command, args []string, lastArg string) (*pflag.Flag, []string, string, error) {
var flagName string
trimmedArgs := args
flagWithEqual := false
if isFlagArg(lastArg) {
if index := strings.Index(lastArg, "="); index >= 0 {
flagName = strings.TrimLeft(lastArg[:index], "-")
lastArg = lastArg[index+1:]
flagWithEqual = true
} else {
return nil, nil, "", errors.New("Unexpected completion request for flag")
}
}
if len(flagName) == 0 {
if len(args) > 0 {
prevArg := args[len(args)-1]
if isFlagArg(prevArg) {
// Only consider the case where the flag does not contain an =.
// If the flag contains an = it means it has already been fully processed,
// so we don't need to deal with it here.
if index := strings.Index(prevArg, "="); index < 0 {
flagName = strings.TrimLeft(prevArg, "-")
// Remove the uncompleted flag or else there could be an error created
// for an invalid value for that flag
trimmedArgs = args[:len(args)-1]
}
}
}
}
if len(flagName) == 0 {
// Not doing flag completion
return nil, trimmedArgs, lastArg, nil
}
flag := findFlag(finalCmd, flagName)
if flag == nil {
// Flag not supported by this command, nothing to complete
err := fmt.Errorf("Subcommand '%s' does not support flag '%s'", finalCmd.Name(), flagName)
return nil, nil, "", err
}
if !flagWithEqual {
if len(flag.NoOptDefVal) != 0 {
// We had assumed dealing with a two-word flag but the flag is a boolean flag.
// In that case, there is no value following it, so we are not really doing flag completion.
// Reset everything to do noun completion.
trimmedArgs = args
flag = nil
}
}
return flag, trimmedArgs, lastArg, nil
}
func findFlag(cmd *Command, name string) *pflag.Flag {
flagSet := cmd.Flags()
if len(name) == 1 {
// First convert the short flag into a long flag
// as the cmd.Flag() search only accepts long flags
if short := flagSet.ShorthandLookup(name); short != nil {
name = short.Name
} else {
set := cmd.InheritedFlags()
if short = set.ShorthandLookup(name); short != nil {
name = short.Name
} else {
return nil
}
}
}
return cmd.Flag(name)
}
// CompDebug prints the specified string to the same file as where the
// completion script prints its logs.
// Note that completion printouts should never be on stdout as they would
// be wrongly interpreted as actual completion choices by the completion script.
func CompDebug(msg string, printToStdErr bool) {
msg = fmt.Sprintf("[Debug] %s", msg)
// Such logs are only printed when the user has set the environment
// 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)
if err == nil {
defer f.Close()
f.WriteString(msg)
}
}
if printToStdErr {
// Must print to stderr for this not to be read by the completion script.
fmt.Fprintf(os.Stderr, msg)
}
}
// CompDebugln prints the specified string with a newline at the end
// to the same file as where the completion script prints its logs.
// Such logs are only printed when the user has set the environment
// variable BASH_COMP_DEBUG_FILE to the path of some file to be used.
func CompDebugln(msg string, printToStdErr bool) {
CompDebug(fmt.Sprintf("%s\n", msg), printToStdErr)
}
// CompError prints the specified completion message to stderr.
func CompError(msg string) {
msg = fmt.Sprintf("[Error] %s", msg)
CompDebug(msg, true)
}
// CompErrorln prints the specified completion message to stderr with a newline at the end.
func CompErrorln(msg string) {
CompError(fmt.Sprintf("%s\n", msg))
}