From 9b2703f557e30e4a3fe4277fdd7980cf588e4f8a Mon Sep 17 00:00:00 2001
From: artemp <artem@mapnik.org>
Date: Fri, 21 Jun 2013 14:47:38 +0100
Subject: [PATCH] + to_string based on spirit::karma for completeness.

---
 src/color.cpp | 38 +++++++++++++++++++++-----------------
 1 file changed, 21 insertions(+), 17 deletions(-)

diff --git a/src/color.cpp b/src/color.cpp
index 4c5e6b38b..a71086664 100644
--- a/src/color.cpp
+++ b/src/color.cpp
@@ -30,6 +30,7 @@
 
 // boost
 #include <boost/spirit/include/karma.hpp>
+#include <boost/spirit/include/phoenix_statement.hpp>
 // stl
 #include <sstream>
 
@@ -42,23 +43,26 @@ color::color(std::string const& str)
 
 std::string color::to_string() const
 {
-    std::stringstream ss;
-    if (alpha_ == 255)
-    {
-        ss << "rgb("
-           << static_cast<unsigned>(red())   << ","
-           << static_cast<unsigned>(green()) << ","
-           << static_cast<unsigned>(blue())  << ")";
-    }
-    else
-    {
-        ss << "rgba("
-           << static_cast<unsigned>(red())   << ","
-           << static_cast<unsigned>(green()) << ","
-           << static_cast<unsigned>(blue()) << ","
-           << alpha() / 255.0 << ")";
-    }
-    return ss.str();
+    namespace karma = boost::spirit::karma;
+    using boost::spirit::karma::_1;
+    using boost::spirit::karma::eps;
+    using boost::spirit::karma::double_;
+    using boost::spirit::karma::string;
+    boost::spirit::karma::uint_generator<uint8_t,10> color_generator;
+    std::string str;
+    std::back_insert_iterator<std::string> sink(str);
+    karma::generate(sink,
+                    // begin grammar
+                    string[ phoenix::if_(alpha()==255) [_1="rgb("].else_[_1="rgba("]]
+                    << color_generator[_1 = red()] << ','
+                    << color_generator[_1 = green()] << ','
+                    << color_generator[_1 = blue()]
+                    << string[ phoenix::if_(alpha()==255) [_1 = ')'].else_[_1 =',']]
+                    << eps(alpha()<255) << ',' << double_ [_1 = alpha()/255.0]
+                    << ')'
+                    // end grammar
+        );
+    return str;
 }
 
 std::string color::to_hex_string() const