Match string in string

eval_test.go

@@ -274,6 +274,16 @@ var evalTests = []evalTest{
 		nil,
 		false,
 	},
+	{
+		`"bar" in "foobar"`,
+		nil,
+		true,
+	},
+	{
+		`"bar" in "world"`,
+		nil,
+		false,
+	},
 	{
 		`A == nil`,
 		struct{ A interface{} }{nil},
@@ -450,7 +460,7 @@ var evalErrorTests = []evalErrorTest{
 	{
 		`1 in "a"`,
 		nil,
-		`operator "in" not defined on string`,
+		`cannot use float64 with "in" operator and string`,
 	},
 	{
 		`nil in map`,

runtime.go

@@ -3,6 +3,7 @@ package expr
 import (
 	"fmt"
 	"reflect"
+	"strings"
 )
 
 func toNumber(n Node, val interface{}) float64 {
@@ -153,6 +154,12 @@ func contains(needle interface{}, array interface{}) (bool, error) {
 				return contains(needle, value.Interface())
 			}
 			return false, nil
+		case reflect.String:
+			n := reflect.ValueOf(needle)
+			if !n.IsValid() || n.Kind() != reflect.String {
+				return false, fmt.Errorf("cannot use %T with \"in\" operator and string", needle)
+			}
+			return strings.Contains(v.String(), n.String()), nil
 		}
 		return false, fmt.Errorf("operator \"in\" not defined on %T", array)
 	}

type.go

@@ -92,6 +92,9 @@ func (n binaryNode) Type(table typesTable) (reflect.Type, error) {
 		if isArrayType(rtype) || isMapType(rtype) || isInterfaceType(rtype) {
 			return boolType, nil
 		}
+		if isStringType(ltype) && isStringType(rtype) {
+			return boolType, nil
+		}
 		return nil, fmt.Errorf(`invalid operation: %v (mismatched types %v and %v)`, n, ltype, rtype)
 
 	case "<", ">", ">=", "<=":

type_test.go

@@ -56,6 +56,7 @@ var typeTests = []typeTest{
 	"Str in Foo",
 	"Str in Arr",
 	"nil in Arr",
+	"Str in Str",
 	"Str not in Foo2p",
 	"Int | Num",
 	"Int ^ Num",
@@ -279,10 +280,6 @@ var typeErrorTests = []typeErrorTest{
 		"NilFn() and OkFn()",
 		"invalid operation: NilFn() and OkFn() (mismatched types <nil> and bool)",
 	},
-	{
-		"'str' in Str",
-		`invalid operation: "str" in Str (mismatched types string and string)`,
-	},
 	{
 		"1 in Foo",
 		"invalid operation: 1 in Foo (mismatched types float64 and *expr_test.foo)",