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custom_completions.go
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custom_completions.go
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package cobra
import (
"fmt"
"os"
"strings"
"github.com/spf13/pflag"
)
const (
// 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 scripts.
ShellCompRequestCmd = "__complete"
// ShellCompNoDescRequestCmd is the name of the hidden command that is used to request
// completion results without their description. It is used by the shell completion scripts.
ShellCompNoDescRequestCmd = "__completeNoDesc"
)
// 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
// ShellCompDirectiveFilterFileExt indicates that the provided completions
// should be used as file extension filters.
// For flags, using Command.MarkFlagFilename() and Command.MarkPersistentFlagFilename()
// is a shortcut to using this directive explicitly. The BashCompFilenameExt
// annotation can also be used to obtain the same behavior for flags.
ShellCompDirectiveFilterFileExt
// ShellCompDirectiveFilterDirs indicates that only directory names should
// be provided in file completion. To request directory names within another
// directory, the returned completions should specify the directory within
// which to search. The BashCompSubdirsInDir annotation can be used to
// obtain the same behavior but only for flags.
ShellCompDirectiveFilterDirs
// ===========================================================================
// All directives using iota should be above this one.
// For internal use.
shellCompDirectiveMaxValue
// ShellCompDirectiveDefault indicates to let the shell perform its default
// behavior after completions have been provided.
// This one must be last to avoid messing up the iota count.
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 d&ShellCompDirectiveFilterFileExt != 0 {
directives = append(directives, "ShellCompDirectiveFilterFileExt")
}
if d&ShellCompDirectiveFilterDirs != 0 {
directives = append(directives, "ShellCompDirectiveFilterDirs")
}
if len(directives) == 0 {
directives = append(directives, "ShellCompDirectiveDefault")
}
if d >= shellCompDirectiveMaxValue {
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),
Aliases: []string{ShellCompNoDescRequestCmd},
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
}
noDescriptions := (cmd.CalledAs() == ShellCompNoDescRequestCmd)
for _, comp := range completions {
if noDescriptions {
// Remove any description that may be included following a tab character.
comp = strings.Split(comp, "\t")[0]
}
// Make sure we only write the first line to the output.
// This is needed if a description contains a linebreak.
// Otherwise the shell scripts will interpret the other lines as new flags
// and could therefore provide a wrong completion.
comp = strings.Split(comp, "\n")[0]
// Finally trim the completion. This is especially important to get rid
// of a trailing tab when there are no description following it.
// For example, a sub-command without a description should not be completed
// with a tab at the end (or else zsh will show a -- following it
// although there is no description).
comp = strings.TrimSpace(comp)
// Print each possible completion to stdout for the completion script to consume.
fmt.Fprintln(finalCmd.OutOrStdout(), comp)
}
if directive >= shellCompDirectiveMaxValue {
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) {
// 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]
var finalCmd *Command
var finalArgs []string
var err error
// Find the real command for which completion must be performed
// check if we need to traverse here to parse local flags on parent commands
if c.Root().TraverseChildren {
finalCmd, finalArgs, err = c.Root().Traverse(trimmedArgs)
} else {
finalCmd, finalArgs, err = c.Root().Find(trimmedArgs)
}
if err != nil {
// Unable to find the real command. E.g., <program> someInvalidCmd <TAB>
return c, []string{}, ShellCompDirectiveDefault, fmt.Errorf("Unable to find a command for arguments: %v", trimmedArgs)
}
// Check if we are doing flag value completion before parsing the flags.
// This is important because if we are completing a flag value, we need to also
// remove the flag name argument from the list of finalArgs or else the parsing
// could fail due to an invalid value (incomplete) for the flag.
flag, finalArgs, toComplete, err := checkIfFlagCompletion(finalCmd, finalArgs, toComplete)
if err != nil {
// Error while attempting to parse flags
return finalCmd, []string{}, ShellCompDirectiveDefault, err
}
// Parse the flags early so we can check if required flags are set
if err = finalCmd.ParseFlags(finalArgs); err != nil {
return finalCmd, []string{}, ShellCompDirectiveDefault, fmt.Errorf("Error while parsing flags from args %v: %s", finalArgs, err.Error())
}
if flag != nil {
// Check if we are completing a flag value subject to annotations
if validExts, present := flag.Annotations[BashCompFilenameExt]; present {
if len(validExts) != 0 {
// File completion filtered by extensions
return finalCmd, validExts, ShellCompDirectiveFilterFileExt, nil
}
// The annotation requests simple file completion. There is no reason to do
// that since it is the default behavior anyway. Let's ignore this annotation
// in case the program also registered a completion function for this flag.
// Even though it is a mistake on the program's side, let's be nice when we can.
}
if subDir, present := flag.Annotations[BashCompSubdirsInDir]; present {
if len(subDir) == 1 {
// Directory completion from within a directory
return finalCmd, subDir, ShellCompDirectiveFilterDirs, nil
}
// Directory completion
return finalCmd, []string{}, ShellCompDirectiveFilterDirs, nil
}
}
// When doing completion of a flag name, as soon as an argument starts with
// a '-' we know it is a flag. We cannot use isFlagArg() here as it requires
// the flag name to be complete
if flag == nil && len(toComplete) > 0 && toComplete[0] == '-' && !strings.Contains(toComplete, "=") {
var completions []string
// First check for required flags
completions = completeRequireFlags(finalCmd, toComplete)
// If we have not found any required flags, only then can we show regular flags
if len(completions) == 0 {
doCompleteFlags := func(flag *pflag.Flag) {
if !flag.Changed ||
strings.Contains(flag.Value.Type(), "Slice") ||
strings.Contains(flag.Value.Type(), "Array") {
// If the flag is not already present, or if it can be specified multiple times (Array or Slice)
// we suggest it as a completion
completions = append(completions, getFlagNameCompletions(flag, toComplete)...)
}
}
// We cannot use finalCmd.Flags() because we may not have called ParsedFlags() for commands
// that have set DisableFlagParsing; it is ParseFlags() that merges the inherited and
// non-inherited flags.
finalCmd.InheritedFlags().VisitAll(func(flag *pflag.Flag) {
doCompleteFlags(flag)
})
finalCmd.NonInheritedFlags().VisitAll(func(flag *pflag.Flag) {
doCompleteFlags(flag)
})
}
directive := ShellCompDirectiveNoFileComp
if len(completions) == 1 && strings.HasSuffix(completions[0], "=") {
// If there is a single completion, the shell usually adds a space
// after the completion. We don't want that if the flag ends with an =
directive = ShellCompDirectiveNoSpace
}
return finalCmd, completions, directive, nil
}
// 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()
}
var completions []string
directive := ShellCompDirectiveDefault
if flag == nil {
foundLocalNonPersistentFlag := false
// If TraverseChildren is true on the root command we don't check for
// local flags because we can use a local flag on a parent command
if !finalCmd.Root().TraverseChildren {
// Check if there are any local, non-persistent flags on the command-line
localNonPersistentFlags := finalCmd.LocalNonPersistentFlags()
finalCmd.NonInheritedFlags().VisitAll(func(flag *pflag.Flag) {
if localNonPersistentFlags.Lookup(flag.Name) != nil && flag.Changed {
foundLocalNonPersistentFlag = true
}
})
}
// Complete subcommand names, including the help command
if len(finalArgs) == 0 && !foundLocalNonPersistentFlag {
// We only complete sub-commands if:
// - there are no arguments on the command-line and
// - there are no local, non-peristent flag on the command-line or TraverseChildren is true
for _, subCmd := range finalCmd.Commands() {
if subCmd.IsAvailableCommand() || subCmd == finalCmd.helpCommand {
if strings.HasPrefix(subCmd.Name(), toComplete) {
completions = append(completions, fmt.Sprintf("%s\t%s", subCmd.Name(), subCmd.Short))
}
directive = ShellCompDirectiveNoFileComp
}
}
}
// Complete required flags even without the '-' prefix
completions = append(completions, completeRequireFlags(finalCmd, toComplete)...)
// Always complete ValidArgs, even if we are completing a subcommand name.
// This is for commands that have both subcommands and ValidArgs.
if len(finalCmd.ValidArgs) > 0 {
if len(finalArgs) == 0 {
// ValidArgs are only for the first argument
for _, validArg := range finalCmd.ValidArgs {
if strings.HasPrefix(validArg, toComplete) {
completions = append(completions, validArg)
}
}
directive = ShellCompDirectiveNoFileComp
// If no completions were found within commands or ValidArgs,
// see if there are any ArgAliases that should be completed.
if len(completions) == 0 {
for _, argAlias := range finalCmd.ArgAliases {
if strings.HasPrefix(argAlias, toComplete) {
completions = append(completions, argAlias)
}
}
}
}
// If there are ValidArgs specified (even if they don't match), we stop completion.
// Only one of ValidArgs or ValidArgsFunction can be used for a single command.
return finalCmd, completions, directive, nil
}
// Let the logic continue so as to add any ValidArgsFunction completions,
// even if we already found sub-commands.
// This is for commands that have subcommands but also specify a ValidArgsFunction.
}
// 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 defined for this flag or command.
// Call the registered completion function to get the completions.
var comps []string
comps, directive = completionFn(finalCmd, finalArgs, toComplete)
completions = append(completions, comps...)
}
return finalCmd, completions, directive, nil
}
func getFlagNameCompletions(flag *pflag.Flag, toComplete string) []string {
if nonCompletableFlag(flag) {
return []string{}
}
var completions []string
flagName := "--" + flag.Name
if strings.HasPrefix(flagName, toComplete) {
// Flag without the =
completions = append(completions, fmt.Sprintf("%s\t%s", flagName, flag.Usage))
// Why suggest both long forms: --flag and --flag= ?
// This forces the user to *always* have to type either an = or a space after the flag name.
// Let's be nice and avoid making users have to do that.
// Since boolean flags and shortname flags don't show the = form, let's go that route and never show it.
// The = form will still work, we just won't suggest it.
// This also makes the list of suggested flags shorter as we avoid all the = forms.
//
// if len(flag.NoOptDefVal) == 0 {
// // Flag requires a value, so it can be suffixed with =
// flagName += "="
// completions = append(completions, fmt.Sprintf("%s\t%s", flagName, flag.Usage))
// }
}
flagName = "-" + flag.Shorthand
if len(flag.Shorthand) > 0 && strings.HasPrefix(flagName, toComplete) {
completions = append(completions, fmt.Sprintf("%s\t%s", flagName, flag.Usage))
}
return completions
}
func completeRequireFlags(finalCmd *Command, toComplete string) []string {
var completions []string
doCompleteRequiredFlags := func(flag *pflag.Flag) {
if _, present := flag.Annotations[BashCompOneRequiredFlag]; present {
if !flag.Changed {
// If the flag is not already present, we suggest it as a completion
completions = append(completions, getFlagNameCompletions(flag, toComplete)...)
}
}
}
// We cannot use finalCmd.Flags() because we may not have called ParsedFlags() for commands
// that have set DisableFlagParsing; it is ParseFlags() that merges the inherited and
// non-inherited flags.
finalCmd.InheritedFlags().VisitAll(func(flag *pflag.Flag) {
doCompleteRequiredFlags(flag)
})
finalCmd.NonInheritedFlags().VisitAll(func(flag *pflag.Flag) {
doCompleteRequiredFlags(flag)
})
return completions
}
func checkIfFlagCompletion(finalCmd *Command, args []string, lastArg string) (*pflag.Flag, []string, string, error) {
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.
return nil, args, lastArg, nil
}
var flagName string
trimmedArgs := args
flagWithEqual := false
// When doing completion of a flag name, as soon as an argument starts with
// a '-' we know it is a flag. We cannot use isFlagArg() here as that function
// requires the flag name to be complete
if len(lastArg) > 0 && lastArg[0] == '-' {
if index := strings.Index(lastArg, "="); index >= 0 {
// Flag with an =
flagName = strings.TrimLeft(lastArg[:index], "-")
lastArg = lastArg[index+1:]
flagWithEqual = true
} else {
// Normal flag completion
return nil, args, lastArg, nil
}
}
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()
WriteStringAndCheck(f, msg)
}
}
if printToStdErr {
// Must print to stderr for this not to be read by the completion script.
fmt.Fprint(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))
}