60 lines
1.5 KiB
Go
60 lines
1.5 KiB
Go
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package cli
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import (
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"bytes"
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"fmt"
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"log"
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"sort"
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"strings"
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)
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// HelpFunc is the type of the function that is responsible for generating
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// the help output when the CLI must show the general help text.
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type HelpFunc func(map[string]CommandFactory) string
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// BasicHelpFunc generates some basic help output that is usually good enough
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// for most CLI applications.
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func BasicHelpFunc(app string) HelpFunc {
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return func(commands map[string]CommandFactory) string {
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var buf bytes.Buffer
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buf.WriteString(fmt.Sprintf(
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"usage: %s [--version] [--help] <command> [<args>]\n\n",
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app))
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buf.WriteString("Available commands are:\n")
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// Get the list of keys so we can sort them, and also get the maximum
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// key length so they can be aligned properly.
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keys := make([]string, 0, len(commands))
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maxKeyLen := 0
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for key, _ := range commands {
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if len(key) > maxKeyLen {
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maxKeyLen = len(key)
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}
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keys = append(keys, key)
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}
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sort.Strings(keys)
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for _, key := range keys {
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commandFunc, ok := commands[key]
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if !ok {
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// This should never happen since we JUST built the list of
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// keys.
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panic("command not found: " + key)
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}
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command, err := commandFunc()
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if err != nil {
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log.Printf("[ERR] cli: Command '%s' failed to load: %s",
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key, err)
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continue
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}
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key = fmt.Sprintf("%s%s", key, strings.Repeat(" ", maxKeyLen-len(key)))
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buf.WriteString(fmt.Sprintf(" %s %s\n", key, command.Synopsis()))
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}
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return buf.String()
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}
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}
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