vise/go/engine/loop.go

48 lines
925 B
Go

package engine
import (
"bufio"
"bytes"
"context"
"fmt"
"io"
"log"
"strings"
)
func Loop(en *Engine, startSym string, ctx context.Context, reader io.Reader, writer io.Writer) error {
err := en.Init(startSym, ctx)
if err != nil {
return fmt.Errorf("cannot init: %v\n", err)
}
b := bytes.NewBuffer(nil)
en.WriteResult(b)
fmt.Println(b.String())
running := true
bufReader := bufio.NewReader(reader)
for running {
in, err := bufReader.ReadString('\n')
if err == io.EOF {
log.Printf("EOF found, that's all folks")
return nil
}
if err != nil {
return fmt.Errorf("cannot read input: %v\n", err)
}
in = strings.TrimSpace(in)
running, err = en.Exec([]byte(in), ctx)
if err != nil {
return fmt.Errorf("unexpected termination: %v\n", err)
}
//b := bytes.NewBuffer(nil)
err = en.WriteResult(writer)
if err != nil {
return err
}
writer.Write([]byte{0x0a})
}
return nil
}