49 lines
871 B
Go
49 lines
871 B
Go
package command
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import (
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"errors"
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"fmt"
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"io"
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"strings"
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"text/tabwriter"
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)
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var ErrHelp = errors.New("help requested")
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type helpBuilder struct {
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n *node
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prefix []string
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}
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func (h *helpBuilder) writeHelp(w io.Writer) error {
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if _, err := fmt.Fprintf(w,
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"\nUsage:\t%s%s COMMAND [OPTIONS]\n\nCommands:\n",
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strings.Join(h.prefix, " "), &h.n.su); err != nil {
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return err
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}
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tw := tabwriter.NewWriter(w, 0, 1, 4, ' ', 0)
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if err := h.writeCommands(h.n.child, tw); err != nil {
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return err
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}
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if err := tw.Flush(); err != nil {
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return err
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}
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_, err := w.Write([]byte{'\n'})
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if err == nil {
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err = ErrHelp
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}
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return err
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}
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func (h *helpBuilder) writeCommands(n *node, w io.Writer) error {
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if n == nil {
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return nil
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}
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if _, err := fmt.Fprintf(w, "\t%s\t%s\n", n.name, n.usage); err != nil {
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return err
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}
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return h.writeCommands(n.next, w)
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}
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