From 3be97c61805361b46bfbf0695ef483ae3a3f4685 Mon Sep 17 00:00:00 2001
From: marecabo <23156476+marecabo@users.noreply.github.com>
Date: Tue, 10 Oct 2023 09:42:35 +0200
Subject: [PATCH] Support EnumMaps

---
 .../org/matsim/core/config/ReflectiveConfigGroup.java     | 5 +++--
 .../org/matsim/core/config/ReflectiveConfigGroupTest.java | 8 ++++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/matsim/src/main/java/org/matsim/core/config/ReflectiveConfigGroup.java b/matsim/src/main/java/org/matsim/core/config/ReflectiveConfigGroup.java
index 391c1577394..7d6d86f0a4d 100644
--- a/matsim/src/main/java/org/matsim/core/config/ReflectiveConfigGroup.java
+++ b/matsim/src/main/java/org/matsim/core/config/ReflectiveConfigGroup.java
@@ -433,8 +433,9 @@ private Object fromString(String value, Class<?> type, @Nullable Field paramFiel
 			} else if (paramField != null && paramField.getGenericType() instanceof ParameterizedType pType) {
 				Class<?> keyClass = TypeFactory.rawClass(pType.getActualTypeArguments()[0]);
 				Class<?> valueClass = TypeFactory.rawClass(pType.getActualTypeArguments()[1]);
-				JavaType mapType = OBJECT_MAPPER.getTypeFactory().constructMapType(
-						LinkedHashMap.class, keyClass, valueClass);
+				Class<? extends Map> mapClass = keyClass.isEnum() ? EnumMap.class : LinkedHashMap.class;
+				JavaType mapType = OBJECT_MAPPER.getTypeFactory().constructMapType(mapClass, keyClass,
+						valueClass);
 				try {
 					return OBJECT_MAPPER.readValue(value, mapType);
 				} catch (JsonProcessingException e) {
diff --git a/matsim/src/test/java/org/matsim/core/config/ReflectiveConfigGroupTest.java b/matsim/src/test/java/org/matsim/core/config/ReflectiveConfigGroupTest.java
index e410b659522..b19c1552100 100644
--- a/matsim/src/test/java/org/matsim/core/config/ReflectiveConfigGroupTest.java
+++ b/matsim/src/test/java/org/matsim/core/config/ReflectiveConfigGroupTest.java
@@ -27,6 +27,7 @@
 import java.time.LocalTime;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.EnumMap;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
@@ -74,6 +75,8 @@ public void testDumpAndRead() {
 		dumpedModule.integerMapField = Map.of("a\"b", 1, "b", 2);
 		dumpedModule.localDateMapField = Map.of('d', LocalDate.of(2023, 10, 9));
 		dumpedModule.booleanMapField = Map.of(0.1, true);
+		dumpedModule.enumMapField = new EnumMap<>(MyEnum.class);
+		dumpedModule.enumMapField.put(MyEnum.VALUE1, "abc");
 		dumpedModule.setField = ImmutableSet.of("a", "b", "c");
 		dumpedModule.listField = List.of("1", "2", "3");
 		assertEqualAfterDumpAndRead(dumpedModule);
@@ -198,6 +201,7 @@ public void testComments() {
 		expectedComments.put("integerMapField", "map of Integer");
 		expectedComments.put("localDateMapField", "map of LocalDate");
 		expectedComments.put("booleanMapField", "map of Boolean");
+		expectedComments.put("enumMapField", "map of Enum");
 
 		assertThat(new MyModule().getComments()).isEqualTo(expectedComments);
 	}
@@ -515,6 +519,10 @@ private static class MyModule extends ReflectiveConfigGroup {
 		@Parameter
 		private Map<Double, Boolean> booleanMapField;
 
+		@Comment("map of Enum")
+		@Parameter
+		private Map<MyEnum, String> enumMapField;
+
 		// Object fields:
 		// Id: string representation is toString
 		private Id<Link> idField;