layers: move get_layer_for_surface() to .cpp

Signed-off-by: Marcus Fritzsch <marcus_fritzsch@mentor.com>

1 files changed, 24 insertions, 1 deletions

diff --git a/src/layers.cpp b/src/layers.cpp
index 8bd9b8f..07586ad 100644
--- a/src/layers.cpp
+++ b/src/layers.cpp
@@ -2,8 +2,10 @@
 // Created by m on 7/27/17.
 //
 
-#include "layers.hpp"
+#include <algorithm>
+
 #include "json_helper.hpp"
+#include "layers.hpp"
 #include "util.hpp"
 
 namespace wm {
@@ -45,4 +47,25 @@ struct result<struct surface_id_to_layer_map> to_surface_id_to_layer_map(
    }
 }
 
+// Helper to allow std::lower_bound with a int key only
+inline bool
+   operator<(struct surface_id_to_layer const &a, int b) {
+   return a.id_max < b;
+}
+
+optional<int> surface_id_to_layer_map::get_layer_for_surface(int surface_id) {
+   auto i = std::lower_bound(std::cbegin(this->mapping),
+                             std::cend(this->mapping), surface_id);
+
+   if (i != this->mapping.end()) {
+      // std::less only checks for surface_id_to_layer::id_max, so check
+      // that we are actually inside of an interval here.
+      if (i->id_min <= surface_id) {
+         return optional<int>(i->layer_id);
+      }
+   }
+
+   return nullopt;
+}
+
 }  // namespace wm