From 04546d0a09d4c3e12e5e2bbd3be6cc026b3b2143 Mon Sep 17 00:00:00 2001
From: Andreas Bichinger <andreas.bichinger@gmail.com>
Date: Tue, 3 May 2022 14:07:01 +0200
Subject: [PATCH] add map support

---
 dummies_test.go    | 11 +++++++++--
 evaluationStage.go | 45 +++++++++++++++++++++++++++++++--------------
 evaluation_test.go | 16 +++++++++++++++-
 3 files changed, 55 insertions(+), 17 deletions(-)

diff --git a/dummies_test.go b/dummies_test.go
index e3a1a2e..6f4bf56 100644
--- a/dummies_test.go
+++ b/dummies_test.go
@@ -3,6 +3,7 @@ package govaluate
 import (
 	"errors"
 	"fmt"
+	"strings"
 )
 
 /*
@@ -14,6 +15,7 @@ type dummyParameter struct {
 	BoolFalse bool
 	Nil       interface{}
 	Nested    dummyNestedParameter
+	Map       map[string]interface{}
 }
 
 func (this dummyParameter) Func() string {
@@ -33,9 +35,9 @@ func (this dummyParameter) FuncArgStr(arg1 string) string {
 }
 
 func (this dummyParameter) TestArgs(str string, ui uint, ui8 uint8, ui16 uint16, ui32 uint32, ui64 uint64, i int, i8 int8, i16 int16, i32 int32, i64 int64, f32 float32, f64 float64, b bool) string {
-	
+
 	var sum float64
-	
+
 	sum = float64(ui) + float64(ui8) + float64(ui16) + float64(ui32) + float64(ui64)
 	sum += float64(i) + float64(i8) + float64(i16) + float64(i32) + float64(i64)
 	sum += float64(f32)
@@ -67,6 +69,11 @@ var dummyParameterInstance = dummyParameter{
 	Nested: dummyNestedParameter{
 		Funk: "funkalicious",
 	},
+	Map: map[string]interface{}{
+		"String":        "string!",
+		"Int":           101,
+		"StringCompare": strings.Compare,
+	},
 }
 
 var fooParameter = EvaluationParameter{
diff --git a/evaluationStage.go b/evaluationStage.go
index 11ea587..a19b49b 100644
--- a/evaluationStage.go
+++ b/evaluationStage.go
@@ -313,6 +313,7 @@ func makeAccessorStage(pair []string) evaluationOperator {
 			}
 		}()
 
+	LOOP:
 		for i := 1; i < len(pair); i++ {
 
 			coreValue := reflect.ValueOf(value)
@@ -325,24 +326,40 @@ func makeAccessorStage(pair []string) evaluationOperator {
 				coreValue = coreValue.Elem()
 			}
 
-			if coreValue.Kind() != reflect.Struct {
-				return nil, errors.New("Unable to access '" + pair[i] + "', '" + pair[i-1] + "' is not a struct")
-			}
-
-			field := coreValue.FieldByName(pair[i])
-			if field != (reflect.Value{}) {
-				value = field.Interface()
-				continue
-			}
+			var field reflect.Value
+			var method reflect.Value
 
-			method := coreValue.MethodByName(pair[i])
-			if method == (reflect.Value{}) {
-				if corePtrVal.IsValid() {
-					method = corePtrVal.MethodByName(pair[i])
+			switch coreValue.Kind() {
+			case reflect.Struct:
+				field = coreValue.FieldByName(pair[i])
+				if field != (reflect.Value{}) {
+					value = field.Interface()
+					continue LOOP
 				}
+
+				method = coreValue.MethodByName(pair[i])
 				if method == (reflect.Value{}) {
-					return nil, errors.New("No method or field '" + pair[i] + "' present on parameter '" + pair[i-1] + "'")
+					if corePtrVal.IsValid() {
+						method = corePtrVal.MethodByName(pair[i])
+					}
 				}
+			case reflect.Map:
+				field = coreValue.MapIndex(reflect.ValueOf(pair[i]))
+				if field != (reflect.Value{}) {
+					inter := field.Interface()
+					if reflect.TypeOf(inter).Kind() == reflect.Func {
+						method = reflect.ValueOf(inter)
+					} else {
+						value = inter
+						continue LOOP
+					}
+				}
+			default:
+				return nil, errors.New("Unable to access '" + pair[i] + "', '" + pair[i-1] + "' is not a struct or map")
+			}
+
+			if method == (reflect.Value{}) {
+				return nil, errors.New("No method or field '" + pair[i] + "' present on parameter '" + pair[i-1] + "'")
 			}
 
 			switch right.(type) {
diff --git a/evaluation_test.go b/evaluation_test.go
index a2b65e8..56c1272 100644
--- a/evaluation_test.go
+++ b/evaluation_test.go
@@ -710,7 +710,7 @@ func TestNoParameterEvaluation(test *testing.T) {
 			Expected: true,
 		},
 		EvaluationTest{
-			
+
 			Name:  "Ternary/Java EL ambiguity",
 			Input: "false ? foo:length()",
 			Functions: map[string]ExpressionFunction{
@@ -1391,6 +1391,20 @@ func TestParameterizedEvaluation(test *testing.T) {
 			Parameters: []EvaluationParameter{fooParameter},
 			Expected:   "funkalicious",
 		},
+		EvaluationTest{
+
+			Name:       "Nested Map string",
+			Input:      "foo.Map.String",
+			Parameters: []EvaluationParameter{fooParameter},
+			Expected:   "string!",
+		},
+		EvaluationTest{
+
+			Name:       "Nested Map function",
+			Input:      `foo.Map.StringCompare("foo", "bar")`,
+			Parameters: []EvaluationParameter{fooParameter},
+			Expected:   1.0,
+		},
 		EvaluationTest{
 
 			Name:       "Parameter call with + modifier",