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package commands
import (
"strings"
)
type completionType int
const (
NONE completionType = iota
COMMAND
OPERAND
SHORT_OPTION
OPTION_ARGUMENT
)
type parser struct {
tokens []string
optind int
spec string
space bool
kind completionType
flag string
arg string
err error
}
func newParser(cmd, spec string, spaceTerminated bool) (*parser, error) {
args, err := splitCmd(cmd)
if err != nil {
return nil, err
}
p := &parser{
tokens: args,
optind: 0,
spec: spec,
space: spaceTerminated,
kind: NONE,
flag: "",
arg: "",
err: nil,
}
state := command
for state != nil {
state = state(p)
}
return p, p.err
}
func (p *parser) empty() bool {
return len(p.tokens) == 0
}
func (p *parser) peek() string {
return p.tokens[0]
}
func (p *parser) advance() string {
if p.empty() {
return ""
}
tok := p.tokens[0]
p.tokens = p.tokens[1:]
p.optind++
return tok
}
func (p *parser) set(t completionType) {
p.kind = t
}
func (p *parser) hasArgument() bool {
n := len(p.flag)
if n > 0 {
s := string(p.flag[n-1]) + ":"
return strings.Contains(p.spec, s)
}
return false
}
type stateFn func(*parser) stateFn
func command(p *parser) stateFn {
p.set(COMMAND)
p.advance()
return peek(p)
}
func peek(p *parser) stateFn {
if p.empty() {
if p.space {
return operand
}
return nil
}
if p.spec == "" {
return operand
}
s := p.peek()
switch {
case s == "--":
p.advance()
case strings.HasPrefix(s, "-"):
return short_option
}
return operand
}
func short_option(p *parser) stateFn {
p.set(SHORT_OPTION)
tok := p.advance()
p.flag = tok[1:]
if p.hasArgument() {
return option_argument
}
return peek(p)
}
func option_argument(p *parser) stateFn {
p.set(OPTION_ARGUMENT)
p.arg = p.advance()
if p.empty() && len(p.arg) == 0 {
return nil
}
return peek(p)
}
func operand(p *parser) stateFn {
p.set(OPERAND)
return nil
}
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