wip

vendor/github.com/antonmedv/expr/checker/checker.go

@@ -0,0 +1,597 @@
+package checker
+
+import (
+	"fmt"
+	"reflect"
+
+	"github.com/antonmedv/expr/ast"
+	"github.com/antonmedv/expr/conf"
+	"github.com/antonmedv/expr/file"
+	"github.com/antonmedv/expr/parser"
+)
+
+func Check(tree *parser.Tree, config *conf.Config) (reflect.Type, error) {
+	v := &visitor{
+		collections: make([]reflect.Type, 0),
+	}
+	if config != nil {
+		v.types = config.Types
+		v.operators = config.Operators
+		v.expect = config.Expect
+		v.strict = config.Strict
+		v.defaultType = config.DefaultType
+	}
+
+	t := v.visit(tree.Node)
+
+	if v.expect != reflect.Invalid {
+		switch v.expect {
+		case reflect.Int64, reflect.Float64:
+			if !isNumber(t) {
+				return nil, fmt.Errorf("expected %v, but got %v", v.expect, t)
+			}
+		default:
+			if t.Kind() != v.expect {
+				return nil, fmt.Errorf("expected %v, but got %v", v.expect, t)
+			}
+		}
+	}
+
+	if v.err != nil {
+		return t, v.err.Bind(tree.Source)
+	}
+
+	return t, nil
+}
+
+type visitor struct {
+	types       conf.TypesTable
+	operators   conf.OperatorsTable
+	expect      reflect.Kind
+	collections []reflect.Type
+	strict      bool
+	defaultType reflect.Type
+	err         *file.Error
+}
+
+func (v *visitor) visit(node ast.Node) reflect.Type {
+	var t reflect.Type
+	switch n := node.(type) {
+	case *ast.NilNode:
+		t = v.NilNode(n)
+	case *ast.IdentifierNode:
+		t = v.IdentifierNode(n)
+	case *ast.IntegerNode:
+		t = v.IntegerNode(n)
+	case *ast.FloatNode:
+		t = v.FloatNode(n)
+	case *ast.BoolNode:
+		t = v.BoolNode(n)
+	case *ast.StringNode:
+		t = v.StringNode(n)
+	case *ast.UnaryNode:
+		t = v.UnaryNode(n)
+	case *ast.BinaryNode:
+		t = v.BinaryNode(n)
+	case *ast.MatchesNode:
+		t = v.MatchesNode(n)
+	case *ast.PropertyNode:
+		t = v.PropertyNode(n)
+	case *ast.IndexNode:
+		t = v.IndexNode(n)
+	case *ast.SliceNode:
+		t = v.SliceNode(n)
+	case *ast.MethodNode:
+		t = v.MethodNode(n)
+	case *ast.FunctionNode:
+		t = v.FunctionNode(n)
+	case *ast.BuiltinNode:
+		t = v.BuiltinNode(n)
+	case *ast.ClosureNode:
+		t = v.ClosureNode(n)
+	case *ast.PointerNode:
+		t = v.PointerNode(n)
+	case *ast.ConditionalNode:
+		t = v.ConditionalNode(n)
+	case *ast.ArrayNode:
+		t = v.ArrayNode(n)
+	case *ast.MapNode:
+		t = v.MapNode(n)
+	case *ast.PairNode:
+		t = v.PairNode(n)
+	default:
+		panic(fmt.Sprintf("undefined node type (%T)", node))
+	}
+	node.SetType(t)
+	return t
+}
+
+func (v *visitor) error(node ast.Node, format string, args ...interface{}) reflect.Type {
+	if v.err == nil { // show first error
+		v.err = &file.Error{
+			Location: node.Location(),
+			Message:  fmt.Sprintf(format, args...),
+		}
+	}
+	return interfaceType // interface represent undefined type
+}
+
+func (v *visitor) NilNode(*ast.NilNode) reflect.Type {
+	return nilType
+}
+
+func (v *visitor) IdentifierNode(node *ast.IdentifierNode) reflect.Type {
+	if v.types == nil {
+		return interfaceType
+	}
+	if t, ok := v.types[node.Value]; ok {
+		if t.Ambiguous {
+			return v.error(node, "ambiguous identifier %v", node.Value)
+		}
+		return t.Type
+	}
+	if !v.strict {
+		if v.defaultType != nil {
+			return v.defaultType
+		}
+		return interfaceType
+	}
+	return v.error(node, "unknown name %v", node.Value)
+}
+
+func (v *visitor) IntegerNode(*ast.IntegerNode) reflect.Type {
+	return integerType
+}
+
+func (v *visitor) FloatNode(*ast.FloatNode) reflect.Type {
+	return floatType
+}
+
+func (v *visitor) BoolNode(*ast.BoolNode) reflect.Type {
+	return boolType
+}
+
+func (v *visitor) StringNode(*ast.StringNode) reflect.Type {
+	return stringType
+}
+
+func (v *visitor) UnaryNode(node *ast.UnaryNode) reflect.Type {
+	t := v.visit(node.Node)
+
+	switch node.Operator {
+
+	case "!", "not":
+		if isBool(t) {
+			return boolType
+		}
+
+	case "+", "-":
+		if isNumber(t) {
+			return t
+		}
+
+	default:
+		return v.error(node, "unknown operator (%v)", node.Operator)
+	}
+
+	return v.error(node, `invalid operation: %v (mismatched type %v)`, node.Operator, t)
+}
+
+func (v *visitor) BinaryNode(node *ast.BinaryNode) reflect.Type {
+	l := v.visit(node.Left)
+	r := v.visit(node.Right)
+
+	// check operator overloading
+	if fns, ok := v.operators[node.Operator]; ok {
+		t, _, ok := conf.FindSuitableOperatorOverload(fns, v.types, l, r)
+		if ok {
+			return t
+		}
+	}
+
+	switch node.Operator {
+	case "==", "!=":
+		if isNumber(l) && isNumber(r) {
+			return boolType
+		}
+		if isComparable(l, r) {
+			return boolType
+		}
+
+	case "or", "||", "and", "&&":
+		if isBool(l) && isBool(r) {
+			return boolType
+		}
+
+	case "in", "not in":
+		if isString(l) && isStruct(r) {
+			return boolType
+		}
+		if isMap(r) {
+			return boolType
+		}
+		if isArray(r) {
+			return boolType
+		}
+
+	case "<", ">", ">=", "<=":
+		if isNumber(l) && isNumber(r) {
+			return boolType
+		}
+		if isString(l) && isString(r) {
+			return boolType
+		}
+
+	case "/", "-", "*":
+		if isNumber(l) && isNumber(r) {
+			return combined(l, r)
+		}
+
+	case "**":
+		if isNumber(l) && isNumber(r) {
+			return floatType
+		}
+
+	case "%":
+		if isInteger(l) && isInteger(r) {
+			return combined(l, r)
+		}
+
+	case "+":
+		if isNumber(l) && isNumber(r) {
+			return combined(l, r)
+		}
+		if isString(l) && isString(r) {
+			return stringType
+		}
+
+	case "contains", "startsWith", "endsWith":
+		if isString(l) && isString(r) {
+			return boolType
+		}
+
+	case "..":
+		if isInteger(l) && isInteger(r) {
+			return reflect.SliceOf(integerType)
+		}
+
+	default:
+		return v.error(node, "unknown operator (%v)", node.Operator)
+
+	}
+
+	return v.error(node, `invalid operation: %v (mismatched types %v and %v)`, node.Operator, l, r)
+}
+
+func (v *visitor) MatchesNode(node *ast.MatchesNode) reflect.Type {
+	l := v.visit(node.Left)
+	r := v.visit(node.Right)
+
+	if isString(l) && isString(r) {
+		return boolType
+	}
+
+	return v.error(node, `invalid operation: matches (mismatched types %v and %v)`, l, r)
+}
+
+func (v *visitor) PropertyNode(node *ast.PropertyNode) reflect.Type {
+	t := v.visit(node.Node)
+
+	if t, ok := fieldType(t, node.Property); ok {
+		return t
+	}
+
+	return v.error(node, "type %v has no field %v", t, node.Property)
+}
+
+func (v *visitor) IndexNode(node *ast.IndexNode) reflect.Type {
+	t := v.visit(node.Node)
+	i := v.visit(node.Index)
+
+	if t, ok := indexType(t); ok {
+		if !isInteger(i) && !isString(i) {
+			return v.error(node, "invalid operation: cannot use %v as index to %v", i, t)
+		}
+		return t
+	}
+
+	return v.error(node, "invalid operation: type %v does not support indexing", t)
+}
+
+func (v *visitor) SliceNode(node *ast.SliceNode) reflect.Type {
+	t := v.visit(node.Node)
+
+	_, isIndex := indexType(t)
+
+	if isIndex || isString(t) {
+		if node.From != nil {
+			from := v.visit(node.From)
+			if !isInteger(from) {
+				return v.error(node.From, "invalid operation: non-integer slice index %v", from)
+			}
+		}
+		if node.To != nil {
+			to := v.visit(node.To)
+			if !isInteger(to) {
+				return v.error(node.To, "invalid operation: non-integer slice index %v", to)
+			}
+		}
+		return t
+	}
+
+	return v.error(node, "invalid operation: cannot slice %v", t)
+}
+
+func (v *visitor) FunctionNode(node *ast.FunctionNode) reflect.Type {
+	if f, ok := v.types[node.Name]; ok {
+		if fn, ok := isFuncType(f.Type); ok {
+
+			inputParamsCount := 1 // for functions
+			if f.Method {
+				inputParamsCount = 2 // for methods
+			}
+
+			if !isInterface(fn) &&
+				fn.IsVariadic() &&
+				fn.NumIn() == inputParamsCount &&
+				fn.NumOut() == 1 &&
+				fn.Out(0).Kind() == reflect.Interface {
+				rest := fn.In(fn.NumIn() - 1) // function has only one param for functions and two for methods
+				if rest.Kind() == reflect.Slice && rest.Elem().Kind() == reflect.Interface {
+					node.Fast = true
+				}
+			}
+
+			return v.checkFunc(fn, f.Method, node, node.Name, node.Arguments)
+		}
+	}
+	if !v.strict {
+		if v.defaultType != nil {
+			return v.defaultType
+		}
+		return interfaceType
+	}
+	return v.error(node, "unknown func %v", node.Name)
+}
+
+func (v *visitor) MethodNode(node *ast.MethodNode) reflect.Type {
+	t := v.visit(node.Node)
+	if f, method, ok := methodType(t, node.Method); ok {
+		if fn, ok := isFuncType(f); ok {
+			return v.checkFunc(fn, method, node, node.Method, node.Arguments)
+		}
+	}
+	return v.error(node, "type %v has no method %v", t, node.Method)
+}
+
+// checkFunc checks func arguments and returns "return type" of func or method.
+func (v *visitor) checkFunc(fn reflect.Type, method bool, node ast.Node, name string, arguments []ast.Node) reflect.Type {
+	if isInterface(fn) {
+		return interfaceType
+	}
+
+	if fn.NumOut() == 0 {
+		return v.error(node, "func %v doesn't return value", name)
+	}
+	if fn.NumOut() != 1 {
+		return v.error(node, "func %v returns more then one value", name)
+	}
+
+	numIn := fn.NumIn()
+
+	// If func is method on an env, first argument should be a receiver,
+	// and actual arguments less then numIn by one.
+	if method {
+		numIn--
+	}
+
+	if fn.IsVariadic() {
+		if len(arguments) < numIn-1 {
+			return v.error(node, "not enough arguments to call %v", name)
+		}
+	} else {
+		if len(arguments) > numIn {
+			return v.error(node, "too many arguments to call %v", name)
+		}
+		if len(arguments) < numIn {
+			return v.error(node, "not enough arguments to call %v", name)
+		}
+	}
+
+	offset := 0
+
+	// Skip first argument in case of the receiver.
+	if method {
+		offset = 1
+	}
+
+	for i, arg := range arguments {
+		t := v.visit(arg)
+
+		var in reflect.Type
+		if fn.IsVariadic() && i >= numIn-1 {
+			// For variadic arguments fn(xs ...int), go replaces type of xs (int) with ([]int).
+			// As we compare arguments one by one, we need underling type.
+			in = fn.In(fn.NumIn() - 1)
+			in, _ = indexType(in)
+		} else {
+			in = fn.In(i + offset)
+		}
+
+		if isIntegerOrArithmeticOperation(arg) {
+			t = in
+			setTypeForIntegers(arg, t)
+		}
+
+		if t == nil {
+			continue
+		}
+
+		if !t.AssignableTo(in) && t.Kind() != reflect.Interface {
+			return v.error(arg, "cannot use %v as argument (type %v) to call %v ", t, in, name)
+		}
+	}
+
+	return fn.Out(0)
+}
+
+func (v *visitor) BuiltinNode(node *ast.BuiltinNode) reflect.Type {
+	switch node.Name {
+
+	case "len":
+		param := v.visit(node.Arguments[0])
+		if isArray(param) || isMap(param) || isString(param) {
+			return integerType
+		}
+		return v.error(node, "invalid argument for len (type %v)", param)
+
+	case "all", "none", "any", "one":
+		collection := v.visit(node.Arguments[0])
+		if !isArray(collection) {
+			return v.error(node.Arguments[0], "builtin %v takes only array (got %v)", node.Name, collection)
+		}
+
+		v.collections = append(v.collections, collection)
+		closure := v.visit(node.Arguments[1])
+		v.collections = v.collections[:len(v.collections)-1]
+
+		if isFunc(closure) &&
+			closure.NumOut() == 1 &&
+			closure.NumIn() == 1 && isInterface(closure.In(0)) {
+
+			if !isBool(closure.Out(0)) {
+				return v.error(node.Arguments[1], "closure should return boolean (got %v)", closure.Out(0).String())
+			}
+			return boolType
+		}
+		return v.error(node.Arguments[1], "closure should has one input and one output param")
+
+	case "filter":
+		collection := v.visit(node.Arguments[0])
+		if !isArray(collection) {
+			return v.error(node.Arguments[0], "builtin %v takes only array (got %v)", node.Name, collection)
+		}
+
+		v.collections = append(v.collections, collection)
+		closure := v.visit(node.Arguments[1])
+		v.collections = v.collections[:len(v.collections)-1]
+
+		if isFunc(closure) &&
+			closure.NumOut() == 1 &&
+			closure.NumIn() == 1 && isInterface(closure.In(0)) {
+
+			if !isBool(closure.Out(0)) {
+				return v.error(node.Arguments[1], "closure should return boolean (got %v)", closure.Out(0).String())
+			}
+			if isInterface(collection) {
+				return arrayType
+			}
+			return reflect.SliceOf(collection.Elem())
+		}
+		return v.error(node.Arguments[1], "closure should has one input and one output param")
+
+	case "map":
+		collection := v.visit(node.Arguments[0])
+		if !isArray(collection) {
+			return v.error(node.Arguments[0], "builtin %v takes only array (got %v)", node.Name, collection)
+		}
+
+		v.collections = append(v.collections, collection)
+		closure := v.visit(node.Arguments[1])
+		v.collections = v.collections[:len(v.collections)-1]
+
+		if isFunc(closure) &&
+			closure.NumOut() == 1 &&
+			closure.NumIn() == 1 && isInterface(closure.In(0)) {
+
+			return reflect.SliceOf(closure.Out(0))
+		}
+		return v.error(node.Arguments[1], "closure should has one input and one output param")
+
+	case "count":
+		collection := v.visit(node.Arguments[0])
+		if !isArray(collection) {
+			return v.error(node.Arguments[0], "builtin %v takes only array (got %v)", node.Name, collection)
+		}
+
+		v.collections = append(v.collections, collection)
+		closure := v.visit(node.Arguments[1])
+		v.collections = v.collections[:len(v.collections)-1]
+
+		if isFunc(closure) &&
+			closure.NumOut() == 1 &&
+			closure.NumIn() == 1 && isInterface(closure.In(0)) {
+			if !isBool(closure.Out(0)) {
+				return v.error(node.Arguments[1], "closure should return boolean (got %v)", closure.Out(0).String())
+			}
+
+			return integerType
+		}
+		return v.error(node.Arguments[1], "closure should has one input and one output param")
+
+	default:
+		return v.error(node, "unknown builtin %v", node.Name)
+	}
+}
+
+func (v *visitor) ClosureNode(node *ast.ClosureNode) reflect.Type {
+	t := v.visit(node.Node)
+	return reflect.FuncOf([]reflect.Type{interfaceType}, []reflect.Type{t}, false)
+}
+
+func (v *visitor) PointerNode(node *ast.PointerNode) reflect.Type {
+	if len(v.collections) == 0 {
+		return v.error(node, "cannot use pointer accessor outside closure")
+	}
+
+	collection := v.collections[len(v.collections)-1]
+
+	if t, ok := indexType(collection); ok {
+		return t
+	}
+	return v.error(node, "cannot use %v as array", collection)
+}
+
+func (v *visitor) ConditionalNode(node *ast.ConditionalNode) reflect.Type {
+	c := v.visit(node.Cond)
+	if !isBool(c) {
+		return v.error(node.Cond, "non-bool expression (type %v) used as condition", c)
+	}
+
+	t1 := v.visit(node.Exp1)
+	t2 := v.visit(node.Exp2)
+
+	if t1 == nil && t2 != nil {
+		return t2
+	}
+	if t1 != nil && t2 == nil {
+		return t1
+	}
+	if t1 == nil && t2 == nil {
+		return nilType
+	}
+	if t1.AssignableTo(t2) {
+		return t1
+	}
+	return interfaceType
+}
+
+func (v *visitor) ArrayNode(node *ast.ArrayNode) reflect.Type {
+	for _, node := range node.Nodes {
+		_ = v.visit(node)
+	}
+	return arrayType
+}
+
+func (v *visitor) MapNode(node *ast.MapNode) reflect.Type {
+	for _, pair := range node.Pairs {
+		v.visit(pair)
+	}
+	return mapType
+}
+
+func (v *visitor) PairNode(node *ast.PairNode) reflect.Type {
+	v.visit(node.Key)
+	v.visit(node.Value)
+	return nilType
+}

vendor/github.com/antonmedv/expr/checker/types.go

@@ -0,0 +1,349 @@
+package checker
+
+import (
+	"reflect"
+
+	"github.com/antonmedv/expr/ast"
+)
+
+var (
+	nilType       = reflect.TypeOf(nil)
+	boolType      = reflect.TypeOf(true)
+	integerType   = reflect.TypeOf(int(0))
+	floatType     = reflect.TypeOf(float64(0))
+	stringType    = reflect.TypeOf("")
+	arrayType     = reflect.TypeOf([]interface{}{})
+	mapType       = reflect.TypeOf(map[string]interface{}{})
+	interfaceType = reflect.TypeOf(new(interface{})).Elem()
+)
+
+func typeWeight(t reflect.Type) int {
+	switch t.Kind() {
+	case reflect.Uint:
+		return 1
+	case reflect.Uint8:
+		return 2
+	case reflect.Uint16:
+		return 3
+	case reflect.Uint32:
+		return 4
+	case reflect.Uint64:
+		return 5
+	case reflect.Int:
+		return 6
+	case reflect.Int8:
+		return 7
+	case reflect.Int16:
+		return 8
+	case reflect.Int32:
+		return 9
+	case reflect.Int64:
+		return 10
+	case reflect.Float32:
+		return 11
+	case reflect.Float64:
+		return 12
+	default:
+		return 0
+	}
+}
+
+func combined(a, b reflect.Type) reflect.Type {
+	if typeWeight(a) > typeWeight(b) {
+		return a
+	} else {
+		return b
+	}
+}
+
+func dereference(t reflect.Type) reflect.Type {
+	if t == nil {
+		return nil
+	}
+	if t.Kind() == reflect.Ptr {
+		t = dereference(t.Elem())
+	}
+	return t
+}
+
+func isComparable(l, r reflect.Type) bool {
+	l = dereference(l)
+	r = dereference(r)
+
+	if l == nil || r == nil { // It is possible to compare with nil.
+		return true
+	}
+	if l.Kind() == r.Kind() {
+		return true
+	}
+	if isInterface(l) || isInterface(r) {
+		return true
+	}
+	return false
+}
+
+func isInterface(t reflect.Type) bool {
+	t = dereference(t)
+	if t != nil {
+		switch t.Kind() {
+		case reflect.Interface:
+			return true
+		}
+	}
+	return false
+}
+
+func isInteger(t reflect.Type) bool {
+	t = dereference(t)
+	if t != nil {
+		switch t.Kind() {
+		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+			fallthrough
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			return true
+		case reflect.Interface:
+			return true
+		}
+	}
+	return false
+}
+
+func isFloat(t reflect.Type) bool {
+	t = dereference(t)
+	if t != nil {
+		switch t.Kind() {
+		case reflect.Float32, reflect.Float64:
+			return true
+		case reflect.Interface:
+			return true
+		}
+	}
+	return false
+}
+
+func isNumber(t reflect.Type) bool {
+	return isInteger(t) || isFloat(t)
+}
+
+func isBool(t reflect.Type) bool {
+	t = dereference(t)
+	if t != nil {
+		switch t.Kind() {
+		case reflect.Bool:
+			return true
+		case reflect.Interface:
+			return true
+		}
+	}
+	return false
+}
+
+func isString(t reflect.Type) bool {
+	t = dereference(t)
+	if t != nil {
+		switch t.Kind() {
+		case reflect.String:
+			return true
+		case reflect.Interface:
+			return true
+		}
+	}
+	return false
+}
+
+func isArray(t reflect.Type) bool {
+	t = dereference(t)
+	if t != nil {
+		switch t.Kind() {
+		case reflect.Slice, reflect.Array:
+			return true
+		case reflect.Interface:
+			return true
+		}
+	}
+	return false
+}
+
+func isMap(t reflect.Type) bool {
+	t = dereference(t)
+	if t != nil {
+		switch t.Kind() {
+		case reflect.Map:
+			return true
+		case reflect.Interface:
+			return true
+		}
+	}
+	return false
+}
+
+func isStruct(t reflect.Type) bool {
+	t = dereference(t)
+	if t != nil {
+		switch t.Kind() {
+		case reflect.Struct:
+			return true
+		}
+	}
+	return false
+}
+
+func isFunc(t reflect.Type) bool {
+	t = dereference(t)
+	if t != nil {
+		switch t.Kind() {
+		case reflect.Func:
+			return true
+		}
+	}
+	return false
+}
+
+func fieldType(ntype reflect.Type, name string) (reflect.Type, bool) {
+	ntype = dereference(ntype)
+	if ntype != nil {
+		switch ntype.Kind() {
+		case reflect.Interface:
+			return interfaceType, true
+		case reflect.Struct:
+			// First check all struct's fields.
+			for i := 0; i < ntype.NumField(); i++ {
+				f := ntype.Field(i)
+				if f.Name == name {
+					return f.Type, true
+				}
+			}
+
+			// Second check fields of embedded structs.
+			for i := 0; i < ntype.NumField(); i++ {
+				f := ntype.Field(i)
+				if f.Anonymous {
+					if t, ok := fieldType(f.Type, name); ok {
+						return t, true
+					}
+				}
+			}
+		case reflect.Map:
+			return ntype.Elem(), true
+		}
+	}
+
+	return nil, false
+}
+
+func methodType(t reflect.Type, name string) (reflect.Type, bool, bool) {
+	if t != nil {
+		// First, check methods defined on type itself,
+		// independent of which type it is.
+		if m, ok := t.MethodByName(name); ok {
+			if t.Kind() == reflect.Interface {
+				// In case of interface type method will not have a receiver,
+				// and to prevent checker decreasing numbers of in arguments
+				// return method type as not method (second argument is false).
+				return m.Type, false, true
+			} else {
+				return m.Type, true, true
+			}
+		}
+
+		d := t
+		if t.Kind() == reflect.Ptr {
+			d = t.Elem()
+		}
+
+		switch d.Kind() {
+		case reflect.Interface:
+			return interfaceType, false, true
+		case reflect.Struct:
+			// First, check all struct's fields.
+			for i := 0; i < d.NumField(); i++ {
+				f := d.Field(i)
+				if !f.Anonymous && f.Name == name {
+					return f.Type, false, true
+				}
+			}
+
+			// Second, check fields of embedded structs.
+			for i := 0; i < d.NumField(); i++ {
+				f := d.Field(i)
+				if f.Anonymous {
+					if t, method, ok := methodType(f.Type, name); ok {
+						return t, method, true
+					}
+				}
+			}
+
+		case reflect.Map:
+			return d.Elem(), false, true
+		}
+	}
+	return nil, false, false
+}
+
+func indexType(ntype reflect.Type) (reflect.Type, bool) {
+	ntype = dereference(ntype)
+	if ntype == nil {
+		return nil, false
+	}
+
+	switch ntype.Kind() {
+	case reflect.Interface:
+		return interfaceType, true
+	case reflect.Map, reflect.Array, reflect.Slice:
+		return ntype.Elem(), true
+	}
+
+	return nil, false
+}
+
+func isFuncType(ntype reflect.Type) (reflect.Type, bool) {
+	ntype = dereference(ntype)
+	if ntype == nil {
+		return nil, false
+	}
+
+	switch ntype.Kind() {
+	case reflect.Interface:
+		return interfaceType, true
+	case reflect.Func:
+		return ntype, true
+	}
+
+	return nil, false
+}
+
+func isIntegerOrArithmeticOperation(node ast.Node) bool {
+	switch n := node.(type) {
+	case *ast.IntegerNode:
+		return true
+	case *ast.UnaryNode:
+		switch n.Operator {
+		case "+", "-":
+			return true
+		}
+	case *ast.BinaryNode:
+		switch n.Operator {
+		case "+", "/", "-", "*":
+			return true
+		}
+	}
+	return false
+}
+
+func setTypeForIntegers(node ast.Node, t reflect.Type) {
+	switch n := node.(type) {
+	case *ast.IntegerNode:
+		n.SetType(t)
+	case *ast.UnaryNode:
+		switch n.Operator {
+		case "+", "-":
+			setTypeForIntegers(n.Node, t)
+		}
+	case *ast.BinaryNode:
+		switch n.Operator {
+		case "+", "/", "-", "*":
+			setTypeForIntegers(n.Left, t)
+			setTypeForIntegers(n.Right, t)
+		}
+	}
+}