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vm.go
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vm.go
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package vm
import (
"context"
"errors"
"fmt"
"reflect"
"github.com/dgrr/pako/ast"
"github.com/dgrr/pako/env"
"github.com/dgrr/pako/over"
)
// Options provides options to run VM with
type Options struct {
// DisableGo disables the usage of `go` statements.
DisableGo bool
MaxMemoryUsage int64
Debug bool // run in Debug mode
}
type (
// Error is a VM run error.
Error struct {
Message string
Pos ast.Position
}
// runInfo provides run incoming and outgoing information
runInfoStruct struct {
recv reflect.Value
memUsage int64
vmTypes []string
// incoming
ctx context.Context
env *env.Env
options *Options
stmt ast.Stmt
expr ast.Expr
operator ast.Operator
// outgoing
rv reflect.Value
callErr int
err error
}
vmStruct struct {
v reflect.Value
}
)
func (runInfo *runInfoStruct) runDecls(ctx context.Context) {
mStmt := runInfo.stmt
defer func() {
runInfo.stmt = mStmt
}()
if stmts, ok := runInfo.stmt.(*ast.StmtsStmt); ok {
for i := 0; runInfo.err == nil && i < len(stmts.Stmts); i++ {
select {
case <-ctx.Done():
return
default:
}
stmt := stmts.Stmts[i]
remove := false
switch st := stmt.(type) {
case *ast.StructStmt: // struct declaration
runInfo.stmt = st
runInfo.runSingleStmt() // struct declared if no nil is returned
remove = true
case *ast.ExprStmt: // can be a function
if fn, ok := st.Expr.(*ast.FuncExpr); ok && fn.Recv != "" {
styp, err := runInfo.env.Type(fn.Recv)
if err != nil {
runInfo.err = newStringError(fn, fn.Recv+" not declared at this point")
} else {
runInfo.expr = fn
ftyp := runInfo.funcExpr()
// we need to store the value in some way...
runInfo.env.DefineMethod(fn.Recv+"."+fn.Name, runInfo.rv)
ns := make([]reflect.StructField, styp.NumField()+1)
for i := 0; i < styp.NumField(); i++ {
ns[i] = styp.Field(i)
}
ns[len(ns)-1] = reflect.StructField{
Name: fn.Name,
Type: ftyp,
}
runInfo.rv = nilValue
runInfo.env.DefineReflectType(fn.Recv, reflect.StructOf(ns))
remove = true
}
}
}
if remove {
stmts.Stmts = append(stmts.Stmts[:i], stmts.Stmts[i+1:]...)
i--
}
}
}
}
func getUnderlyingType(v reflect.Value) interface{} {
for v.Type() == reflectValueType {
v = v.Interface().(reflect.Value)
}
return v.Interface()
}
func getSizeOf(v reflect.Value) int64 {
for v.Type() == reflectValueType {
v = v.Interface().(reflect.Value)
}
x := int(v.Type().Size())
switch v.Kind() {
case reflect.Slice, reflect.Array,
reflect.Chan, reflect.String, reflect.Map:
x = 0
if v.Kind() == reflect.Map {
it := v.MapRange()
for it.Next() {
vl := it.Key()
for vl.Type() == reflectValueType {
vl = v.Interface().(reflect.Value)
}
x += int(vl.Type().Size())
vl = it.Value()
for vl.Type() == reflectValueType {
vl = v.Interface().(reflect.Value)
}
x += int(vl.Type().Size())
}
} else {
for i := 0; i < v.Len(); i++ {
vl := v.Index(i)
for vl.Type() == reflectValueType {
vl = v.Interface().(reflect.Value)
}
x += int(vl.Type().Size())
}
}
}
return int64(x)
}
func (runInfo *runInfoStruct) allocMemUsage(v reflect.Value) {
//runInfo.memUsage += getSizeOf(v)
}
func (runInfo *runInfoStruct) deallocMemUsage(v reflect.Value) {
//runInfo.memUsage -= getSizeOf(v)
}
var (
nilType = reflect.TypeOf(nil)
stringType = reflect.TypeOf("a")
byteType = reflect.TypeOf(byte('a'))
runeType = reflect.TypeOf('a')
interfaceType = reflect.ValueOf([]interface{}{int64(1)}).Index(0).Type()
interfaceSliceType = reflect.TypeOf([]interface{}{})
reflectValueType = reflect.TypeOf(reflect.Value{})
errorType = reflect.ValueOf([]error{nil}).Index(0).Type()
vmErrorType = reflect.TypeOf(&Error{})
contextType = reflect.TypeOf((*context.Context)(nil)).Elem()
vmStructType = reflect.TypeOf((*vmStruct)(nil))
nilValue = reflect.New(reflect.TypeOf((*interface{})(nil)).Elem()).Elem()
trueValue = reflect.ValueOf(true)
falseValue = reflect.ValueOf(false)
zeroValue = reflect.Value{}
reflectValueNilValue = reflect.ValueOf(nilValue)
reflectValueErrorNilValue = reflect.ValueOf(reflect.New(errorType).Elem())
errInvalidTypeConversion = fmt.Errorf("invalid type conversion")
// ErrBreak when there is an unexpected break statement
ErrBreak = errors.New("unexpected break statement")
// ErrContinue when there is an unexpected continue statement
ErrContinue = errors.New("unexpected continue statement")
// ErrReturn when there is an unexpected return statement
ErrReturn = errors.New("unexpected return statement")
// ErrInterrupt when execution has been interrupted
ErrInterrupt = errors.New("execution interrupted")
)
// Error returns the VM error message.
func (e *Error) Error() string {
return e.Message
}
// newError makes VM error from error
func newError(pos ast.Pos, err error) error {
if err == nil {
return nil
}
if pos == nil {
return &Error{Message: err.Error(), Pos: ast.Position{Line: 1, Column: 1}}
}
return &Error{Message: err.Error(), Pos: pos.Position()}
}
// newStringError makes VM error from string
func newStringError(pos ast.Pos, err string) error {
if err == "" {
return nil
}
if pos == nil {
return &Error{Message: err, Pos: ast.Position{Line: 1, Column: 1}}
}
return &Error{Message: err, Pos: pos.Position()}
}
// recoverFunc generic recover function
func recoverFunc(runInfo *runInfoStruct) {
recoverInterface := recover()
if recoverInterface == nil {
return
}
switch value := recoverInterface.(type) {
case *Error:
runInfo.err = value
case error:
runInfo.err = value
default:
runInfo.err = fmt.Errorf("%v", recoverInterface)
}
}
func isNil(v reflect.Value) bool {
switch v.Kind() {
case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
// from reflect IsNil:
// Note that IsNil is not always equivalent to a regular comparison with nil in Go.
// For example, if v was created by calling ValueOf with an uninitialized interface variable i,
// i==nil will be true but v.IsNil will panic as v will be the zero Value.
return v.IsNil()
default:
return false
}
}
func isNum(v reflect.Value) bool {
switch v.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr,
reflect.Float32, reflect.Float64:
return true
}
return false
}
// equal returns true when lhsV and rhsV is same value.
func equal(lhsV, rhsV reflect.Value) bool {
lhsIsNil, rhsIsNil := isNil(lhsV), isNil(rhsV)
if lhsIsNil && rhsIsNil {
return true
}
if (!lhsIsNil && rhsIsNil) || (lhsIsNil && !rhsIsNil) {
return false
}
if lhsV.Kind() == reflect.Interface || lhsV.Kind() == reflect.Ptr {
lhsV = lhsV.Elem()
}
if rhsV.Kind() == reflect.Interface || rhsV.Kind() == reflect.Ptr {
rhsV = rhsV.Elem()
}
if lhsV.Type().Implements(over.ComparisonReflectType) {
lhv := lhsV.Interface().(over.Comparison)
v := getUnderlyingType(rhsV)
return lhv.Equals(v) == nil
}
// Compare a string and a number.
// This will attempt to convert the string to a number,
// while leaving the other side alone. Code further
// down takes care of converting ints and floats as needed.
if isNum(lhsV) && rhsV.Kind() == reflect.String {
rhsF, err := tryToFloat64(rhsV)
if err != nil {
// Couldn't convert RHS to a float, they can't be compared.
return false
}
rhsV = reflect.ValueOf(rhsF)
} else if lhsV.Kind() == reflect.String && isNum(rhsV) {
// If the LHS is a string formatted as an int, try that before trying float
lhsI, err := tryToInt64(lhsV)
if err != nil {
// if LHS is a float, e.g. "1.2", we need to set lhsV to a float64
lhsF, err := tryToFloat64(lhsV)
if err != nil {
return false
}
lhsV = reflect.ValueOf(lhsF)
} else {
lhsV = reflect.ValueOf(lhsI)
}
}
if isNum(lhsV) && isNum(rhsV) {
return fmt.Sprintf("%v", lhsV) == fmt.Sprintf("%v", rhsV)
}
// Try to compare bools to strings and numbers
if lhsV.Kind() == reflect.Bool || rhsV.Kind() == reflect.Bool {
lhsB, err := tryToBool(lhsV)
if err != nil {
return false
}
rhsB, err := tryToBool(rhsV)
if err != nil {
return false
}
return lhsB == rhsB
}
return reflect.DeepEqual(lhsV.Interface(), rhsV.Interface())
}
func getMapIndex(key reflect.Value, aMap reflect.Value) reflect.Value {
if aMap.IsNil() {
return nilValue
}
var err error
key, err = convertReflectValueToType(key, aMap.Type().Key())
if err != nil {
return nilValue
}
// From reflect MapIndex:
// It returns the zero Value if key is not found in the map or if v represents a nil map.
value := aMap.MapIndex(key)
if !value.IsValid() {
return nilValue
}
if aMap.Type().Elem() == interfaceType && !value.IsNil() {
value = reflect.ValueOf(value.Interface())
}
return value
}
// appendSlice appends rhs to lhs
// function assumes lhsV and rhsV are slice or array
func appendSlice(expr ast.Expr, lhsV reflect.Value, rhsV reflect.Value) (reflect.Value, error) {
lhsT := lhsV.Type().Elem()
rhsT := rhsV.Type().Elem()
if lhsT == rhsT {
return reflect.AppendSlice(lhsV, rhsV), nil
}
if rhsT.ConvertibleTo(lhsT) {
for i := 0; i < rhsV.Len(); i++ {
lhsV = reflect.Append(lhsV, rhsV.Index(i).Convert(lhsT))
}
return lhsV, nil
}
leftHasSubArray := lhsT.Kind() == reflect.Slice || lhsT.Kind() == reflect.Array
rightHasSubArray := rhsT.Kind() == reflect.Slice || rhsT.Kind() == reflect.Array
if leftHasSubArray != rightHasSubArray && lhsT != interfaceType && rhsT != interfaceType {
return nilValue, newStringError(expr, "invalid type conversion")
}
if !leftHasSubArray && !rightHasSubArray {
for i := 0; i < rhsV.Len(); i++ {
value := rhsV.Index(i)
if rhsT == interfaceType {
value = value.Elem()
}
if lhsT == value.Type() {
lhsV = reflect.Append(lhsV, value)
} else if value.Type().ConvertibleTo(lhsT) {
lhsV = reflect.Append(lhsV, value.Convert(lhsT))
} else {
return nilValue, newStringError(expr, "invalid type conversion")
}
}
return lhsV, nil
}
if (leftHasSubArray || lhsT == interfaceType) && (rightHasSubArray || rhsT == interfaceType) {
for i := 0; i < rhsV.Len(); i++ {
value := rhsV.Index(i)
if rhsT == interfaceType {
value = value.Elem()
if value.Kind() != reflect.Slice && value.Kind() != reflect.Array {
return nilValue, newStringError(expr, "invalid type conversion")
}
}
newSlice, err := appendSlice(expr, reflect.MakeSlice(lhsT, 0, value.Len()), value)
if err != nil {
return nilValue, err
}
lhsV = reflect.Append(lhsV, newSlice)
}
return lhsV, nil
}
return nilValue, newStringError(expr, "invalid type conversion")
}
func makeType(runInfo *runInfoStruct, typeStruct *ast.TypeStruct) reflect.Type {
switch typeStruct.Kind {
case ast.TypeDefault:
return getTypeFromEnv(runInfo, typeStruct)
case ast.TypePtr:
var t reflect.Type
if typeStruct.SubType != nil {
t = makeType(runInfo, typeStruct.SubType)
} else {
t = getTypeFromEnv(runInfo, typeStruct)
}
if runInfo.err != nil {
return nil
}
if t == nil {
return nil
}
return reflect.PtrTo(t)
case ast.TypeSlice:
var t reflect.Type
if typeStruct.SubType != nil {
t = makeType(runInfo, typeStruct.SubType)
} else {
t = getTypeFromEnv(runInfo, typeStruct)
}
if runInfo.err != nil {
return nil
}
if t == nil {
return nil
}
for i := 1; i < typeStruct.Dimensions; i++ {
t = reflect.SliceOf(t)
}
return reflect.SliceOf(t)
case ast.TypeMap:
key := makeType(runInfo, typeStruct.Key)
if runInfo.err != nil {
return nil
}
if key == nil {
return nil
}
t := makeType(runInfo, typeStruct.SubType)
if runInfo.err != nil {
return nil
}
if t == nil {
return nil
}
if !runInfo.options.Debug {
// captures panic
defer recoverFunc(runInfo)
}
t = reflect.MapOf(key, t)
return t
case ast.TypeChan:
var t reflect.Type
if typeStruct.SubType != nil {
t = makeType(runInfo, typeStruct.SubType)
} else {
t = getTypeFromEnv(runInfo, typeStruct)
}
if runInfo.err != nil {
return nil
}
if t == nil {
return nil
}
return reflect.ChanOf(reflect.BothDir, t)
case ast.TypeStructType:
var t reflect.Type
fields := make([]reflect.StructField, 0, len(typeStruct.StructNames))
for i := 0; i < len(typeStruct.StructNames); i++ {
t = makeType(runInfo, typeStruct.StructTypes[i])
if runInfo.err != nil {
return nil
}
if t == nil {
return nil
}
fields = append(fields, reflect.StructField{Name: typeStruct.StructNames[i], Type: t})
}
if !runInfo.options.Debug {
// captures panic
defer recoverFunc(runInfo)
}
t = reflect.StructOf(fields)
return t
default:
runInfo.err = fmt.Errorf("unknown kind")
return nil
}
}
func getTypeFromEnv(runInfo *runInfoStruct, typeStruct *ast.TypeStruct) reflect.Type {
var e *env.Env
e, runInfo.err = runInfo.env.GetEnvFromPath(typeStruct.Env)
if runInfo.err != nil {
return nil
}
var t reflect.Type
t, runInfo.err = e.Type(typeStruct.Name)
return t
}
func (runInfo *runInfoStruct) isVMType(name string) (b bool) {
if runInfo == nil {
return
}
for _, T := range runInfo.vmTypes {
if b = T == name; b {
break
}
}
return
}
func makeValue(runInfo *runInfoStruct, name string, t reflect.Type) (reflect.Value, error) {
if t.Implements(over.MemReflectType) {
tl := reflect.New(t).Elem().Interface().(over.Mem)
v, err := tl.New()
return reflect.ValueOf(v), err
}
switch t.Kind() {
case reflect.Chan:
return reflect.MakeChan(t, 0), nil
case reflect.Func:
if t.NumIn() < 2 || t.In(0) != contextType {
return reflect.MakeFunc(t, nil), nil
}
v := t.In(1)
if v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface {
v = v.Elem()
}
V, err := runInfo.env.Method(name)
if err != nil {
return reflect.MakeFunc(t, nil), nil
}
return V, nil
case reflect.Map:
// note creating slice as work around to create map
// just doing MakeMap can give incorrect type for defined types
value := reflect.MakeSlice(reflect.SliceOf(t), 0, 1)
value = reflect.Append(value, reflect.MakeMap(reflect.MapOf(t.Key(), t.Elem())))
return value.Index(0), nil
case reflect.Ptr:
ptrV := reflect.New(t.Elem())
v, err := makeValue(runInfo, "", t.Elem())
if err != nil {
return nilValue, err
}
ptrV.Elem().Set(v)
return ptrV, nil
case reflect.Slice:
return reflect.MakeSlice(t, 0, 0), nil
case reflect.Struct:
structV := reflect.New(t).Elem()
for i := 0; i < structV.NumField(); i++ {
if structV.Field(i).Kind() == reflect.Ptr {
continue
}
v, err := makeValue(runInfo, name+"."+t.Field(i).Name, structV.Field(i).Type())
if err != nil {
return nilValue, err
}
if structV.Field(i).CanSet() {
structV.Field(i).Set(v)
}
}
return structV, nil
}
return reflect.New(t).Elem(), nil
}
// precedenceOfKinds returns the greater of two kinds
// string > float > int
func precedenceOfKinds(kind1 reflect.Kind, kind2 reflect.Kind) reflect.Kind {
if kind1 == kind2 {
return kind1
}
switch kind1 {
case reflect.String:
return kind1
case reflect.Float64, reflect.Float32:
switch kind2 {
case reflect.String:
return kind2
}
return kind1
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
switch kind2 {
case reflect.String, reflect.Float64, reflect.Float32:
return kind2
}
}
return kind1
}