Squashed 'third_party/boostorg/lexical_cast/' content from commit 5bfe667
Change-Id: I518d0a0b83082059176813a98b80ad92892ac745
git-subtree-dir: third_party/boostorg/lexical_cast
git-subtree-split: 5bfe6672d467ebd8de5d911c07b2a931b43156de
diff --git a/example/variant_to_long_double.cpp b/example/variant_to_long_double.cpp
new file mode 100644
index 0000000..9b1aa27
--- /dev/null
+++ b/example/variant_to_long_double.cpp
@@ -0,0 +1,41 @@
+// Copyright 2013-2017 Antony Polukhin
+
+// Distributed under the Boost Software License, Version 1.0.
+// (See the accompanying file LICENSE_1_0.txt
+// or a copy at <http://www.boost.org/LICENSE_1_0.txt>.)
+
+
+//[lexical_cast_variant_to_long_double
+/*`
+ In this example we'll make a `to_long_double` method that converts value of the Boost.Variant to `long double`.
+*/
+
+#include <boost/lexical_cast.hpp>
+#include <boost/variant.hpp>
+#include <cassert>
+
+struct to_long_double_functor: boost::static_visitor<long double> {
+ template <class T>
+ long double operator()(const T& v) const {
+ // Lexical cast has many optimizations including optimizations for situations that usually
+ // occur in generic programming, like std::string to std::string or arithmetic type to arithmetic type conversion.
+ return boost::lexical_cast<long double>(v);
+ }
+};
+
+// Throws `boost::bad_lexical_cast` if value of the variant is not convertible to `long double`
+template <class Variant>
+long double to_long_double(const Variant& v) {
+ return boost::apply_visitor(to_long_double_functor(), v);
+}
+
+int main() {
+ boost::variant<char, int, std::string> v1('0'), v2("10.0001"), v3(1);
+
+ const long double sum = to_long_double(v1) + to_long_double(v2) + to_long_double(v3);
+ const int ret = (sum > 11 && sum < 11.1 ? 0 : 1);
+ assert(ret == 0);
+ return ret;
+}
+
+//] [/lexical_cast_variant_to_long_double]