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fsm.go
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fsm.go
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package cli
import (
"sort"
"strings"
"fmt"
)
type state struct {
id int
terminal bool
transitions transitions
cmd *Cmd
}
type transition struct {
matcher upMatcher
next *state
}
type transitions []*transition
func (t transitions) Len() int { return len(t) }
func (t transitions) Swap(i, j int) { t[i], t[j] = t[j], t[i] }
func (t transitions) Less(i, j int) bool {
a, _ := t[i].matcher, t[j].matcher
switch a.(type) {
case upShortcut:
return false
case upOptsEnd:
return false
case *arg:
return false
default:
return true
}
}
var _id = 0
func newState(cmd *Cmd) *state {
_id++
return &state{_id, false, []*transition{}, cmd}
}
func (s *state) t(matcher upMatcher, next *state) *state {
s.transitions = append(s.transitions, &transition{matcher, next})
return next
}
func (s *state) has(tr *transition) bool {
for _, t := range s.transitions {
if t.next == tr.next && t.matcher == tr.matcher {
return true
}
}
return false
}
func incoming(s, into *state, visited map[*state]bool) []*transition {
res := []*transition{}
if visited[s] {
return res
}
visited[s] = true
for _, tr := range s.transitions {
if tr.next == into {
res = append(res, tr)
}
res = append(res, incoming(tr.next, into, visited)...)
}
return res
}
func removeItemAt(idx int, arr transitions) transitions {
res := make([]*transition, len(arr)-1)
copy(res, arr[:idx])
copy(res[idx:], arr[idx+1:])
return res
}
func fsmCopy(s, e *state) (*state, *state) {
cache := map[*state]*state{}
s.copy(cache)
return cache[s], cache[e]
}
func (s *state) copy(cache map[*state]*state) *state {
c := newState(s.cmd)
c.terminal = s.terminal
cache[s] = c
for _, tr := range s.transitions {
dest := tr.next
if destCopy, found := cache[dest]; found {
c.transitions = append(c.transitions, &transition{tr.matcher, destCopy})
continue
}
c.transitions = append(c.transitions, &transition{tr.matcher, dest.copy(cache)})
}
return c
}
func (s *state) simplify() {
simplify(s, s, map[*state]bool{})
}
func simplify(start, s *state, visited map[*state]bool) {
if visited[s] {
return
}
visited[s] = true
for _, tr := range s.transitions {
simplify(start, tr.next, visited)
}
for s.simplifySelf(start) {
}
}
func (s *state) simplifySelf(start *state) bool {
for idx, tr := range s.transitions {
if _, ok := tr.matcher.(upShortcut); ok {
next := tr.next
s.transitions = removeItemAt(idx, s.transitions)
for _, tr := range next.transitions {
if !s.has(tr) {
s.transitions = append(s.transitions, tr)
}
}
if next.terminal {
s.terminal = true
}
return true
}
}
return false
}
func (s *state) onlyOpts() bool {
return onlyOpts(s, map[*state]bool{})
}
func onlyOpts(s *state, visited map[*state]bool) bool {
if visited[s] {
return true
}
visited[s] = true
for _, tr := range s.transitions {
switch tr.matcher.(type) {
case *arg:
return false
}
if !onlyOpts(tr.next, visited) {
return false
}
}
return true
}
func (s *state) dot() string {
trs := dot(s, map[*state]bool{})
return fmt.Sprintf("digraph G {\n\trankdir=LR\n%s\n}\n", strings.Join(trs, "\n"))
}
func dot(s *state, visited map[*state]bool) []string {
res := []string{}
if visited[s] {
return res
}
visited[s] = true
for _, tr := range s.transitions {
res = append(res, fmt.Sprintf("\tS%d -> S%d [label=\"%v\"]", s.id, tr.next.id, tr.matcher))
res = append(res, dot(tr.next, visited)...)
}
if s.terminal {
res = append(res, fmt.Sprintf("\tS%d [peripheries=2]", s.id))
}
return res
}
type parseContext struct {
args map[*arg][]string
opts map[*opt][]string
rejectOptions bool
}
func newParseContext() parseContext {
return parseContext{map[*arg][]string{}, map[*opt][]string{}, false}
}
func (pc parseContext) merge(o parseContext) {
for k, vs := range o.args {
pc.args[k] = append(pc.args[k], vs...)
}
for k, vs := range o.opts {
pc.opts[k] = append(pc.opts[k], vs...)
}
}
func (s *state) parse(args []string) error {
pc := newParseContext()
ok, err := s.apply(args, pc)
if err != nil {
return err
}
if !ok {
return fmt.Errorf("incorrect usage")
}
for opt, vs := range pc.opts {
for _, v := range vs {
if err := opt.set(v); err != nil {
return err
}
}
}
for arg, vs := range pc.args {
for _, v := range vs {
if err := arg.set(v); err != nil {
return err
}
}
}
return nil
}
func (s *state) apply(args []string, pc parseContext) (bool, error) {
if s.terminal && len(args) == 0 {
return true, nil
}
sort.Sort(s.transitions)
if len(args) > 0 {
arg := args[0]
if !pc.rejectOptions && arg == "--" {
pc.rejectOptions = true
args = args[1:]
}
}
type match struct {
tr *transition
rem []string
pc parseContext
}
matches := []*match{}
for _, tr := range s.transitions {
fresh := newParseContext()
fresh.rejectOptions = pc.rejectOptions
if ok, rem := tr.matcher.match(args, &fresh); ok {
matches = append(matches, &match{tr, rem, fresh})
}
}
for _, m := range matches {
ok, err := m.tr.next.apply(m.rem, m.pc)
if err != nil {
return false, err
}
if ok {
pc.merge(m.pc)
return true, nil
}
}
return false, nil
}