Hilbish/sink.go

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package main
import (
"fmt"
"io"
"hilbish/util"
rt "github.com/arnodel/golua/runtime"
)
var sinkMetaKey = rt.StringValue("hshsink")
// a sink is a structure that has input and/or output
// it is like a lua file when used in popen, but specific to hilbish
type sink struct{
writer io.Writer
reader io.Reader
ud *rt.UserData
}
func setupSinkType(rtm *rt.Runtime) {
sinkMeta := rt.NewTable()
sinkMethods := rt.NewTable()
sinkFuncs := map[string]util.LuaExport{
"write": {luaSinkWrite, 2, false},
"writeln": {luaSinkWriteln, 2, false},
}
util.SetExports(l, sinkMethods, sinkFuncs)
sinkIndex := func(t *rt.Thread, c *rt.GoCont) (rt.Cont, error) {
arg := c.Arg(1)
val := sinkMethods.Get(arg)
return c.PushingNext1(t.Runtime, val), nil
}
sinkMeta.Set(rt.StringValue("__index"), rt.FunctionValue(rt.NewGoFunction(sinkIndex, "__index", 2, false)))
l.SetRegistry(sinkMetaKey, rt.TableValue(sinkMeta))
}
func luaSinkWrite(t *rt.Thread, c *rt.GoCont) (rt.Cont, error) {
if err := c.CheckNArgs(2); err != nil {
return nil, err
}
s, err := sinkArg(c, 0)
if err != nil {
return nil, err
}
data, err := c.StringArg(1)
if err != nil {
return nil, err
}
s.writer.Write([]byte(data))
return c.Next(), nil
}
func luaSinkWriteln(t *rt.Thread, c *rt.GoCont) (rt.Cont, error) {
if err := c.CheckNArgs(2); err != nil {
return nil, err
}
s, err := sinkArg(c, 0)
if err != nil {
return nil, err
}
data, err := c.StringArg(1)
if err != nil {
return nil, err
}
s.writer.Write([]byte(data + "\n"))
return c.Next(), nil
}
func newSinkInput(r io.Reader) *sink {
s := &sink{
reader: r,
}
s.ud = sinkUserData(s)
return s
}
func newSinkOutput(w io.Writer) *sink {
s := &sink{
writer: w,
}
s.ud = sinkUserData(s)
return s
}
func sinkArg(c *rt.GoCont, arg int) (*sink, error) {
s, ok := valueToSink(c.Arg(arg))
if !ok {
return nil, fmt.Errorf("#%d must be a sink", arg + 1)
}
return s, nil
}
func valueToSink(val rt.Value) (*sink, bool) {
u, ok := val.TryUserData()
if !ok {
return nil, false
}
s, ok := u.Value().(*sink)
return s, ok
}
func sinkUserData(s *sink) *rt.UserData {
sinkMeta := l.Registry(sinkMetaKey)
return rt.NewUserData(s, sinkMeta.AsTable())
}