Adding upstream version 14.2.21.upstream/14.2.21upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 102 insertions, 0 deletions

diff --git a/src/boost/libs/proto/example/rgb.cpp b/src/boost/libs/proto/example/rgb.cpp
new file mode 100644
index 00000000..51b0f459
--- /dev/null
+++ b/src/boost/libs/proto/example/rgb.cpp
@@ -0,0 +1,102 @@
+//[ RGB
+///////////////////////////////////////////////////////////////////////////////
+//  Copyright 2008 Eric Niebler. Distributed under the Boost
+//  Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// This is a simple example of doing arbitrary type manipulations with proto
+// transforms. It takes some expression involving primary colors and combines
+// the colors according to arbitrary rules. It is a port of the RGB example
+// from PETE (http://www.codesourcery.com/pooma/download.html).
+
+#include <iostream>
+#include <boost/proto/core.hpp>
+#include <boost/proto/transform.hpp>
+namespace proto = boost::proto;
+
+struct RedTag
+{
+    friend std::ostream &operator <<(std::ostream &sout, RedTag)
+    {
+        return sout << "This expression is red.";
+    }
+};
+
+struct BlueTag
+{
+    friend std::ostream &operator <<(std::ostream &sout, BlueTag)
+    {
+        return sout << "This expression is blue.";
+    }
+};
+
+struct GreenTag
+{
+    friend std::ostream &operator <<(std::ostream &sout, GreenTag)
+    {
+        return sout << "This expression is green.";
+    }
+};
+
+typedef proto::terminal<RedTag>::type RedT;
+typedef proto::terminal<BlueTag>::type BlueT;
+typedef proto::terminal<GreenTag>::type GreenT;
+
+struct Red;
+struct Blue;
+struct Green;
+
+///////////////////////////////////////////////////////////////////////////////
+// A transform that produces new colors according to some arbitrary rules:
+// red & green give blue, red & blue give green, blue and green give red.
+struct Red
+  : proto::or_<
+        proto::plus<Green, Blue>
+      , proto::plus<Blue, Green>
+      , proto::plus<Red, Red>
+      , proto::terminal<RedTag>
+    >
+{};
+
+struct Green
+  : proto::or_<
+        proto::plus<Red, Blue>
+      , proto::plus<Blue, Red>
+      , proto::plus<Green, Green>
+      , proto::terminal<GreenTag>
+    >
+{};
+
+struct Blue
+  : proto::or_<
+        proto::plus<Red, Green>
+      , proto::plus<Green, Red>
+      , proto::plus<Blue, Blue>
+      , proto::terminal<BlueTag>
+    >
+{};
+
+struct RGB
+  : proto::or_<
+        proto::when< Red, RedTag() >
+      , proto::when< Blue, BlueTag() >
+      , proto::when< Green, GreenTag() >
+    >
+{};
+
+template<typename Expr>
+void printColor(Expr const & expr)
+{
+    int i = 0; // dummy state and data parameter, not used
+    std::cout << RGB()(expr, i, i) << std::endl;
+}
+
+int main()
+{
+    printColor(RedT() + GreenT());
+    printColor(RedT() + GreenT() + BlueT());
+    printColor(RedT() + (GreenT() + BlueT()));
+
+    return 0;
+}
+//]