Initial commit

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

common/mergemap/mergemap.go

@@ -0,0 +1,66 @@
+package mergemap
+
+import "reflect"
+
+var MaxDepth = 32
+
+// Merge recursively merges the src and dst maps. Key conflicts are resolved by
+// preferring src, or recursively descending, if both src and dst are maps.
+func Merge(dst, src map[string]interface{}) map[string]interface{} {
+	return merge(dst, src, 0)
+}
+
+func merge(dst, src map[string]interface{}, depth int) map[string]interface{} {
+	if depth > MaxDepth {
+		panic("too deep!")
+	}
+	for key, srcVal := range src {
+		if dstVal, ok := dst[key]; ok {
+			srcMap, srcMapOk := mapify(srcVal)
+			dstMap, dstMapOk := mapify(dstVal)
+			if srcMapOk && dstMapOk {
+				srcVal = merge(dstMap, srcMap, depth+1)
+			}
+		}
+		dst[key] = srcVal
+	}
+	return dst
+}
+
+func Reduce(dst, src map[string]interface{}, method func(a, b interface{}) interface{}) map[string]interface{} {
+	return reduce(dst, src, 0, method)
+}
+
+func reduce(dst, src map[string]interface{}, depth int, method func(a, b interface{}) interface{}) map[string]interface{} {
+	if depth > MaxDepth {
+		panic("too deep!")
+	}
+	for key, srcVal := range src {
+		if dstVal, ok := dst[key]; ok {
+			srcMap, srcMapOk := mapify(srcVal)
+			dstMap, dstMapOk := mapify(dstVal)
+			if srcMapOk && dstMapOk {
+				srcVal = reduce(dstMap, srcMap, depth+1, method)
+			}
+		}
+		value := reflect.ValueOf(srcVal)
+		if value.Kind() == reflect.Map {
+			dst[key] = srcVal
+		} else {
+			dst[key] = method(dst[key], srcVal)
+		}
+	}
+	return dst
+}
+
+func mapify(i interface{}) (map[string]interface{}, bool) {
+	value := reflect.ValueOf(i)
+	if value.Kind() == reflect.Map {
+		m := map[string]interface{}{}
+		for _, k := range value.MapKeys() {
+			m[k.String()] = value.MapIndex(k).Interface()
+		}
+		return m, true
+	}
+	return map[string]interface{}{}, false
+}