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shell.go
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shell.go
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package main
import (
"errors"
"fmt"
"os"
)
type Shell struct {
name string
args []string
cwd string
globals map[string]string
functions map[string]Command
done chan struct{}
exited bool
exitCode int
exported []string
frames []Frame
}
type Frame struct {
name string
args []string
locals map[string]string
returned bool
returnCode int
}
func NewShell(name string, args []string, cwd string) *Shell {
return &Shell{
name: name,
args: args,
cwd: cwd,
globals: map[string]string{},
done: make(chan struct{}),
functions: map[string]Command{},
}
}
func (s *Shell) currentFrame() *Frame {
n := len(s.frames)
if n == 0 {
return nil
}
return &s.frames[n-1]
}
func (s *Shell) PushFrame(name string, args []string) {
s.frames = append(s.frames, Frame{name: name, args: args})
}
func (s *Shell) PopFrame() (int, bool) {
f := s.currentFrame()
if f == nil {
panic("no frame to pop")
}
s.frames = s.frames[:len(s.frames)-1]
return f.returnCode, f.returned
}
func (s *Shell) Return(code int) error {
f := s.currentFrame()
if f == nil {
return errors.New("no function to return from")
}
f.returnCode = code
f.returned = true
return nil
}
func (s *Shell) Returned() bool {
f := s.currentFrame()
return f != nil && f.returned
}
func (s *Shell) GetArg(n int) string {
f := s.currentFrame()
if n == 0 {
if f != nil {
return f.name
}
return s.name
}
var args []string
n--
if f != nil {
args = f.args
} else {
args = s.args
}
if n >= len(args) {
return ""
}
return args[n]
}
func (s *Shell) ArgCount() int {
f := s.currentFrame()
if f != nil {
return len(f.args)
}
return len(s.args)
}
func (s *Shell) GetArgs() []string {
f := s.currentFrame()
if f != nil {
return f.args
}
return s.args
}
func (s *Shell) ShiftArgs(n int) {
f := s.currentFrame()
if f != nil {
f.args = f.args[n:]
} else {
s.args = s.args[n:]
}
}
func (s *Shell) GetVar(name string) string {
var (
val string
ok bool
f = s.currentFrame()
)
if f != nil {
val, ok = f.locals[name]
}
if !ok {
val, ok = s.globals[name]
}
if !ok {
val = os.Getenv(name)
}
return val
}
func (s *Shell) GetFunction(name string) Command {
return s.functions[name]
}
func (s *Shell) Export(name string) {
for _, gname := range s.exported {
if name == gname {
return
}
}
s.exported = append(s.exported, name)
}
func (s *Shell) SetVar(name, val string) {
f := s.currentFrame()
if f != nil {
_, ok := f.locals[name]
if ok {
f.locals[name] = val
return
}
}
s.globals[name] = val
}
func (s *Shell) SetFunction(name string, body Command) {
fmt.Println("Setting function:", name)
s.functions[name] = body
}
func (s *Shell) SetCwd(dir string) error {
cwd, err := LookDir(s.cwd, dir)
if err != nil {
return err
}
s.cwd = cwd
return nil
}
func (s *Shell) GetCwd() string {
return s.cwd
}
func (s *Shell) Exited() bool {
return s.exited
}
func (s *Shell) ShouldStop() bool {
return s.Exited() || s.Returned()
}
func (s *Shell) Exit(code int) {
if !s.exited {
s.exited = true
s.exitCode = code
close(s.done)
}
}
func (s *Shell) ExitCode() int {
return s.exitCode
}
func (s *Shell) Wait() int {
<-s.done
return s.exitCode
}
func (s *Shell) Subshell() *Shell {
args := make([]string, len(s.args))
for i, x := range s.args {
args[i] = x
}
sub := NewShell(s.name, args, s.cwd)
for k, v := range s.globals {
sub.SetVar(k, v)
}
return sub
}