Add lazy.h

1 files changed, 26 insertions, 0 deletions

diff --git a/toolsrc/include/lazy.h b/toolsrc/include/lazy.h
new file mode 100644
index 000000000..f9dbd8dc7
--- /dev/null
+++ b/toolsrc/include/lazy.h
@@ -0,0 +1,26 @@
+#pragma once
+
+namespace vcpkg
+{
+    template <typename T>
+    class lazy
+    {
+    public:
+        lazy() : value(T()), initialized(false) {}
+
+        template <class F>
+        T const& get_lazy(F& f) const
+        {
+            if (!initialized)
+            {
+                value = f();
+                initialized = true;
+            }
+            return value;
+        }
+
+    private:
+        mutable T value;
+        mutable bool initialized;
+    };
+}