diff --git a/ktmidi-ci/src/commonMain/kotlin/dev/atsushieno/ktmidi/ci/propertycommonrules/PropertyPartialUpdater.kt b/ktmidi-ci/src/commonMain/kotlin/dev/atsushieno/ktmidi/ci/propertycommonrules/PropertyPartialUpdater.kt
new file mode 100644
index 00000000..a9dad23b
--- /dev/null
+++ b/ktmidi-ci/src/commonMain/kotlin/dev/atsushieno/ktmidi/ci/propertycommonrules/PropertyPartialUpdater.kt
@@ -0,0 +1,46 @@
+package dev.atsushieno.ktmidi.ci.propertycommonrules
+
+import dev.atsushieno.ktmidi.ci.json.Json
+
+object PropertyPartialUpdater {
+    fun parseJsonPointer(s: String): List<String> =
+        if (s.isNotEmpty() && s[0] == '/')
+            s.substring(1).split('/').map { it.replace("~1", "/").replace("~0", "~") }
+        else listOf()
+
+    fun applyPartialUpdate(obj: Json.JsonValue, path: String, value: Json.JsonValue): Json.JsonValue =
+        applyPartialUpdate(obj, parseJsonPointer(path), value)
+
+    fun applyPartialUpdate(obj: Json.JsonValue, jsonPointerPath: List<String>, value: Json.JsonValue): Json.JsonValue =
+        patch(obj, jsonPointerPath, value)
+
+    private fun patch(obj: Json.JsonValue, path: List<String>, value: Json.JsonValue): Json.JsonValue {
+        val entry = path.firstOrNull() ?: return obj // path is empty
+        if (obj.token.type != Json.TokenType.Object) // obj is not an object
+            return obj
+
+        val contextKey = obj.objectValue.keys.firstOrNull { it.stringValue == entry }
+            ?: return obj // specified path entry does not match
+        // replace context entry with new object which might be recursively alter the content with the new value
+        val replacement = if (path.size == 1) value else patch(obj.objectValue[contextKey]!!, path.drop(1), value)
+        val newMap = obj.objectValue.keys.map {
+            Pair(it, if (it == contextKey) replacement else obj.objectValue[it]!!)
+        }
+        return Json.JsonValue(newMap.toMap())
+    }
+
+    fun applyPartialUpdates(existingJson: Json.JsonValue, partialSpecJson: Json.JsonValue): Pair<Boolean, Json.JsonValue> {
+        val failureReturn = Pair(false, existingJson)
+        if (partialSpecJson.token.type != Json.TokenType.Object)
+            return failureReturn // context should be JSON object
+
+        var target = existingJson
+        // apply all partial updates
+        partialSpecJson.objectValue.keys.forEach {  key ->
+            val path = if (key.token.type == Json.TokenType.String) key.stringValue else return Pair(false, existingJson)
+            val newValue = partialSpecJson.objectValue[key]!!
+            target = applyPartialUpdate(target, path, newValue)
+        }
+        return Pair(true, target)
+    }
+}
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