Fix the semantics of YaPhysicalUIMapList

We're supposed to take the list provided by the host, and modify the
target note expression values.

src/common/serialization/vst3/physical-ui-map-list.cpp

@@ -16,6 +16,8 @@
 
 #include "physical-ui-map-list.h"
 
+#include <cassert>
+
 YaPhysicalUIMapList::YaPhysicalUIMapList() {}
 
 YaPhysicalUIMapList::YaPhysicalUIMapList(
@@ -27,3 +29,14 @@ Steinberg::Vst::PhysicalUIMapList YaPhysicalUIMapList::get() {
         .count = static_cast<Steinberg::uint32>(maps.size()),
         .map = maps.data()};
 }
+
+void YaPhysicalUIMapList::write_back(
+    Steinberg::Vst::PhysicalUIMapList& list) const {
+    assert(list.count == maps.size());
+
+    // Write the note expression IDs as updated by the plugin (if the plugin
+    // updated them) back to the original list we've read from
+    for (Steinberg::uint32 i = 0; i < list.count; i++) {
+        list.map[i].noteExpressionTypeID = maps[i].noteExpressionTypeID;
+    }
+}

src/common/serialization/vst3/physical-ui-map-list.h

@@ -22,7 +22,10 @@
 
 /**
  * Serialization wrapper around `PhysicalUIMapList` that allows loading such a
- * list and recreating one from a `YaPhysicalUIMapList` object.
+ * list and writing the changes made by the plugin back to the original list.
+ * The host provides a list with the `physicalUITypeID` field set for each
+ * mapping, and the plugin then sets the `noteExpressionTypeID` to one of its
+ * note expression of it can handle it.
  */
 class YaPhysicalUIMapList {
    public:
@@ -35,12 +38,19 @@ class YaPhysicalUIMapList {
 
     /**
      * Reconstruct the original `PhysicalUIMapList` object passed to the
-     * constructor and return it. This is used as part of
+     * constructor and return it. This is used to handle
-     * `YaProcessData::get()`. The returned object is valid as long as this
+     * `INoteExpressionPhysicalUIMapping::getPhysicalUIMapping()` on the Wine
-     * object is alive.
+     * plugin host side. The returned object is valid as long as this object is
+     * alive.
      */
     Steinberg::Vst::PhysicalUIMapList get();
 
+    /**
+     * Write the `noteExpressionTypeID` values stored in `maps` back to the
+     * original physical UI mapping list we copied `maps` from.
+     */
+    void write_back(Steinberg::Vst::PhysicalUIMapList& list) const;
+
     template <typename S>
     void serialize(S& s) {
         s.container(maps, 1 << 31);