vise/go/vm/vm.go
2023-03-31 12:41:00 +01:00

84 lines
2.2 KiB
Go

package vm
import (
"encoding/binary"
"fmt"
"context"
"git.defalsify.org/festive/state"
"git.defalsify.org/festive/resource"
)
type Runner func(instruction []byte, st state.State, rs resource.Fetcher, ctx context.Context) (state.State, error)
func Run(instruction []byte, st state.State, rs resource.Fetcher, ctx context.Context) (state.State, error) {
op := binary.BigEndian.Uint16(instruction[:2])
if op > _MAX {
return st, fmt.Errorf("opcode value %v out of range (%v)", op, _MAX)
}
switch op {
case CATCH:
RunCatch(instruction[2:], st, rs, ctx)
case CROAK:
RunCroak(instruction[2:], st, rs, ctx)
case LOAD:
RunLoad(instruction[2:], st, rs, ctx)
case RELOAD:
RunReload(instruction[2:], st, rs, ctx)
case MAP:
RunMap(instruction[2:], st, rs, ctx)
case SINK:
RunSink(instruction[2:], st, rs, ctx)
default:
err := fmt.Errorf("Unhandled state: %v", op)
return st, err
}
return st, nil
}
func instructionSplit(b []byte) (string, []byte, error) {
sz := uint8(b[0])
tailSz := uint8(len(b))
if tailSz - 1 < sz {
return "", nil, fmt.Errorf("corrupt instruction, len %v less than symbol length: %v", tailSz, sz)
}
r := string(b[1:1+sz])
return r, b[1+sz:], nil
}
func RunMap(instruction []byte, st state.State, rs resource.Fetcher, ctx context.Context) (state.State, error) {
head, tail, err := instructionSplit(instruction)
fn, err := rs.FuncFor(head)
if err != nil {
return st, err
}
r, err := fn(tail, ctx)
if err != nil {
return st, err
}
st.Add(head, r)
return st, nil
}
func RunSink(instruction []byte, st state.State, rs resource.Fetcher, ctx context.Context) (state.State, error) {
return st, nil
}
func RunCatch(instruction []byte, st state.State, rs resource.Fetcher, ctx context.Context) (state.State, error) {
return st, nil
}
func RunCroak(instruction []byte, st state.State, rs resource.Fetcher, ctx context.Context) (state.State, error) {
return st, nil
}
func RunLoad(instruction []byte, st state.State, rs resource.Fetcher, ctx context.Context) (state.State, error) {
return st, nil
}
func RunReload(instruction []byte, st state.State, rs resource.Fetcher, ctx context.Context) (state.State, error) {
return st, nil
}