vendor/github.com/posener/complete/complete.go

   1 // Package complete provides a tool for bash writing bash completion in go.
   2 //
   3 // Writing bash completion scripts is a hard work. This package provides an easy way
   4 // to create bash completion scripts for any command, and also an easy way to install/uninstall
   5 // the completion of the command.
   6 package complete
   7
   8 import (
   9         "flag"
  10         "fmt"
  11         "io"
  12         "os"
  13
  14         "github.com/posener/complete/cmd"
  15         "github.com/posener/complete/match"
  16 )
  17
  18 const (
  19         envComplete = "COMP_LINE"
  20         envDebug    = "COMP_DEBUG"
  21 )
  22
  23 // Complete structs define completion for a command with CLI options
  24 type Complete struct {
  25         Command Command
  26         cmd.CLI
  27         Out io.Writer
  28 }
  29
  30 // New creates a new complete command.
  31 // name is the name of command we want to auto complete.
  32 // IMPORTANT: it must be the same name - if the auto complete
  33 // completes the 'go' command, name must be equal to "go".
  34 // command is the struct of the command completion.
  35 func New(name string, command Command) *Complete {
  36         return &Complete{
  37                 Command: command,
  38                 CLI:     cmd.CLI{Name: name},
  39                 Out:     os.Stdout,
  40         }
  41 }
  42
  43 // Run runs the completion and add installation flags beforehand.
  44 // The flags are added to the main flag CommandLine variable.
  45 func (c *Complete) Run() bool {
  46         c.AddFlags(nil)
  47         flag.Parse()
  48         return c.Complete()
  49 }
  50
  51 // Complete a command from completion line in environment variable,
  52 // and print out the complete options.
  53 // returns success if the completion ran or if the cli matched
  54 // any of the given flags, false otherwise
  55 // For installation: it assumes that flags were added and parsed before
  56 // it was called.
  57 func (c *Complete) Complete() bool {
  58         line, ok := getLine()
  59         if !ok {
  60                 // make sure flags parsed,
  61                 // in case they were not added in the main program
  62                 return c.CLI.Run()
  63         }
  64         Log("Completing line: %s", line)
  65         a := newArgs(line)
  66         Log("Completing last field: %s", a.Last)
  67         options := c.Command.Predict(a)
  68         Log("Options: %s", options)
  69
  70         // filter only options that match the last argument
  71         matches := []string{}
  72         for _, option := range options {
  73                 if match.Prefix(option, a.Last) {
  74                         matches = append(matches, option)
  75                 }
  76         }
  77         Log("Matches: %s", matches)
  78         c.output(matches)
  79         return true
  80 }
  81
  82 func getLine() (string, bool) {
  83         line := os.Getenv(envComplete)
  84         if line == "" {
  85                 return "", false
  86         }
  87         return line, true
  88 }
  89
  90 func (c *Complete) output(options []string) {
  91         // stdout of program defines the complete options
  92         for _, option := range options {
  93                 fmt.Fprintln(c.Out, option)
  94         }
  95 }