[light] Replace sparse enum switch with linear search to save 156 bytes RAM (#12140)

esphome/components/light/light_json_schema.cpp

@@ -7,30 +7,29 @@ namespace esphome::light {
 
 // See https://www.home-assistant.io/integrations/light.mqtt/#json-schema for documentation on the schema
 
-// Lookup table for color mode strings
-static constexpr const char *get_color_mode_json_str(ColorMode mode) {
-  switch (mode) {
-    case ColorMode::ON_OFF:
-      return "onoff";
-    case ColorMode::BRIGHTNESS:
-      return "brightness";
-    case ColorMode::WHITE:
-      return "white";  // not supported by HA in MQTT
-    case ColorMode::COLOR_TEMPERATURE:
-      return "color_temp";
-    case ColorMode::COLD_WARM_WHITE:
-      return "cwww";  // not supported by HA
-    case ColorMode::RGB:
-      return "rgb";
-    case ColorMode::RGB_WHITE:
-      return "rgbw";
-    case ColorMode::RGB_COLOR_TEMPERATURE:
-      return "rgbct";  // not supported by HA
-    case ColorMode::RGB_COLD_WARM_WHITE:
-      return "rgbww";
-    default:
-      return nullptr;
+// Get JSON string for color mode using linear search (avoids large switch jump table)
+static const char *get_color_mode_json_str(ColorMode mode) {
+  // Parallel arrays: mode values and their corresponding strings
+  // Uses less RAM than a switch jump table on sparse enum values
+  static constexpr ColorMode MODES[] = {
+      ColorMode::ON_OFF,
+      ColorMode::BRIGHTNESS,
+      ColorMode::WHITE,
+      ColorMode::COLOR_TEMPERATURE,
+      ColorMode::COLD_WARM_WHITE,
+      ColorMode::RGB,
+      ColorMode::RGB_WHITE,
+      ColorMode::RGB_COLOR_TEMPERATURE,
+      ColorMode::RGB_COLD_WARM_WHITE,
+  };
+  static constexpr const char *STRINGS[] = {
+      "onoff", "brightness", "white", "color_temp", "cwww", "rgb", "rgbw", "rgbct", "rgbww",
+  };
+  for (size_t i = 0; i < sizeof(MODES) / sizeof(MODES[0]); i++) {
+    if (MODES[i] == mode)
+      return STRINGS[i];
   }
+  return nullptr;
 }
 
 void LightJSONSchema::dump_json(LightState &state, JsonObject root) {