Add the lookup functions by identifier

src/sfizz/NumericId.h

@@ -27,5 +27,15 @@ struct NumericId {
         return number != -1;
     }
 
+    constexpr bool operator==(NumericId other) const noexcept
+    {
+        return number == other.number;
+    }
+
+    constexpr bool operator!=(NumericId other) const noexcept
+    {
+        return number != other.number;
+    }
+
     const int number = -1;
 };

src/sfizz/Synth.cpp

@@ -1056,6 +1056,40 @@ const sfz::EffectBus* sfz::Synth::getEffectBusView(int idx) const noexcept
     return (size_t)idx < effectBuses.size() ? effectBuses[idx].get() : nullptr;
 }
 
+const sfz::Region* sfz::Synth::getRegionById(NumericId<Region> id) const noexcept
+{
+    const size_t size = regions.size();
+
+    if (size == 0 || !id.valid())
+        return nullptr;
+
+    // search a sequence of ordered identifiers with potential gaps
+    size_t index = static_cast<size_t>(id.number);
+    index = std::min(index, size - 1);
+
+    while (index > 0 && regions[index]->getId().number > id.number)
+        --index;
+
+    return (regions[index]->getId() == id) ? regions[index].get() : nullptr;
+}
+
+const sfz::Voice* sfz::Synth::getVoiceById(NumericId<Voice> id) const noexcept
+{
+    const size_t size = voices.size();
+
+    if (size == 0 || !id.valid())
+        return nullptr;
+
+    // search a sequence of ordered identifiers with potential gaps
+    size_t index = static_cast<size_t>(id.number);
+    index = std::min(index, size - 1);
+
+    while (index > 0 && voices[index]->getId().number > id.number)
+        --index;
+
+    return (voices[index]->getId() == id) ? voices[index].get() : nullptr;
+}
+
 const sfz::Voice* sfz::Synth::getVoiceView(int idx) const noexcept
 {
     return (size_t)idx < voices.size() ? voices[idx].get() : nullptr;

src/sfizz/Synth.h

@@ -178,6 +178,20 @@ public:
      * @brief Export a MIDI Name document describing the loaded instrument
      */
     std::string exportMidnam(absl::string_view model = {}) const;
+    /**
+     * @brief Find the region which is associated with the given identifier.
+     *
+     * @param id
+     * @return const Region*
+     */
+    const Region* getRegionById(NumericId<Region> id) const noexcept;
+    /**
+     * @brief Find the voice which is associated with the given identifier.
+     *
+     * @param id
+     * @return const Voice*
+     */
+    const Voice* getVoiceById(NumericId<Voice> id) const noexcept;
     /**
      * @brief Get a raw view into a specific region. This is mostly used
      * for testing.