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package interpreter
import (
"fmt"
"usebox.net/lang/ast"
"usebox.net/lang/errors"
"usebox.net/lang/tokens"
)
type Callable interface {
Name() string
String() string
Call(interp *Interpreter, args []any, loc tokens.Location) (any, error)
Type() *ast.Type
Params() []ast.Type
Ret() *ast.Type
}
var builtInFuncs = map[string]Callable{
"len": builtInLen{},
"println": builtInPrintln{},
"panic": builtInPanic{},
}
func BuiltInTypes() map[string]ast.Type {
types := map[string]ast.Type{}
for k, v := range builtInFuncs {
types[k] = *v.Type()
}
return types
}
type builtInLen struct{}
func (n builtInLen) Name() string {
return "'len'"
}
func (n builtInLen) Type() *ast.Type {
return ast.NewFuncType(tokens.Token{}, n.Params(), n.Ret())
}
func (n builtInLen) String() string {
return n.Type().String()
}
func (n builtInLen) Params() []ast.Type {
// won't be arity or type checked
return []ast.Type{ast.TypeArray}
}
func (n builtInLen) Ret() *ast.Type {
return &ast.TypeNumber
}
func (n builtInLen) Call(interp *Interpreter, args []any, loc tokens.Location) (any, error) {
vals, ok := args[0].([]any)
if !ok {
// shouldn't happen
return nil, errors.NewError(errors.Unexpected, loc, "type mismatch in call to 'len'")
}
// return
panic(&PanicJump{typ: PanicJumpReturn, value: ast.Number(len(vals))})
}
type builtInPrintln struct{}
func (n builtInPrintln) Name() string {
return "'println'"
}
func (n builtInPrintln) Type() *ast.Type {
return ast.NewFuncType(tokens.Token{}, n.Params(), n.Ret())
}
func (n builtInPrintln) String() string {
return n.Type().String()
}
func (n builtInPrintln) Params() []ast.Type {
// won't be arity or type checked
return nil
}
func (n builtInPrintln) Ret() *ast.Type {
return &ast.TypeNumber
}
func (n builtInPrintln) Call(interp *Interpreter, args []any, loc tokens.Location) (any, error) {
var count int
for i := range args {
if args[i] == nil {
continue
}
written, err := fmt.Print(args[i])
if err != nil {
return nil, err
}
count += written
}
fmt.Println()
count++
// return
panic(&PanicJump{typ: PanicJumpReturn, value: ast.Number(count)})
}
type builtInPanic struct{}
func (n builtInPanic) Name() string {
return "'panic'"
}
func (n builtInPanic) Type() *ast.Type {
return ast.NewFuncType(tokens.Token{}, n.Params(), n.Ret())
}
func (n builtInPanic) String() string {
return n.Type().String()
}
func (n builtInPanic) Params() []ast.Type {
return []ast.Type{ast.TypeString}
}
func (n builtInPanic) Ret() *ast.Type {
// no return (returns none)
return nil
}
func (n builtInPanic) Call(interp *Interpreter, args []any, loc tokens.Location) (any, error) {
return nil, fmt.Errorf("[%s] panic: %s", loc, args[0])
}
type Function struct {
fun ast.Func
closure *Env
}
func (f Function) Name() string {
return f.fun.Name.String()
}
func (f Function) Type() *ast.Type {
return ast.NewFuncType(f.fun.Name, f.Params(), f.Ret())
}
func (f Function) String() string {
return f.Type().String()
}
func (f Function) Params() []ast.Type {
params := make([]ast.Type, 0, 1)
for _, p := range f.fun.Params {
params = append(params, p.Type)
}
return params
}
func (f Function) Ret() *ast.Type {
return f.fun.Ret
}
func (f Function) Call(interp *Interpreter, args []any, loc tokens.Location) (result any, err error) {
pEnv := interp.env
interp.env = NewEnv(f.closure)
defer func() {
interp.env = pEnv
}()
for n, v := range f.fun.Params {
interp.env = interp.env.Set(v.Name.Value, Var{Value: args[n], Loc: v.Name.Loc})
}
// tail call optimization
for {
// wrap the evaluation in a function
var tailCall *PanicJump
tailCall, result, err = func() (tailCall *PanicJump, result any, err error) {
// handle tail call
// will call this function again without setting up a new call frame
defer func() {
if r := recover(); r != nil {
if val, ok := r.(*PanicJump); ok && val.typ == PanicJumpTailCall {
tailCall = val
return
}
panic(r)
}
}()
result, err = interp.evaluate(f.fun.Body)
return nil, result, err
}()
if tailCall == nil {
break
}
// XXX: can we optimize this?
// if the callee can be a variable expression, we probably can't
call := tailCall.value.(ast.Call)
callee, err := interp.evaluate(call.Callee)
if err != nil {
return nil, err
}
if fun, ok := callee.(Callable); !ok || fun.Name() != f.Name() {
// can't be optimized
val, err := interp.evaluate(call)
if err != nil {
return nil, err
}
panic(&PanicJump{typ: PanicJumpReturn, value: val, loc: tailCall.loc})
}
args, err := interp.evalArgs(f.Name(), call.Loc, f.Params(), call.Args)
if err != nil {
return nil, err
}
for n, v := range f.fun.Params {
interp.env.Update(v.Name.Value, args[n])
}
}
return result, err
}
|
