svn merge -r114679:114681 svn+ssh://svn.lindenlab.com/svn/linden/branches/event-system/event-system-7 svn+ssh://svn.lindenlab.com/svn/linden/branches/event-system/event-system-8

1 files changed, 75 insertions, 0 deletions

diff --git a/indra/llcommon/stringize.h b/indra/llcommon/stringize.h
new file mode 100644
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+++ b/indra/llcommon/stringize.h
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+/**
+ * @file   stringize.h
+ * @author Nat Goodspeed
+ * @date   2008-12-17
+ * @brief  stringize(item) template function and STRINGIZE(expression) macro
+ * 
+ * $LicenseInfo:firstyear=2008&license=viewergpl$
+ * Copyright (c) 2008, Linden Research, Inc.
+ * $/LicenseInfo$
+ */
+
+#if ! defined(LL_STRINGIZE_H)
+#define LL_STRINGIZE_H
+
+#include <sstream>
+
+/**
+ * stringize(item) encapsulates an idiom we use constantly, using
+ * operator<<(std::ostringstream&, TYPE) followed by std::ostringstream::str()
+ * to render a string expressing some item.
+ */
+template <typename T>
+std::string stringize(const T& item)
+{
+    std::ostringstream out;
+    out << item;
+    return out.str();
+}
+
+/**
+ * STRINGIZE(item1 << item2 << item3 ...) effectively expands to the
+ * following:
+ * @code
+ * std::ostringstream out;
+ * out << item1 << item2 << item3 ... ;
+ * return out.str();
+ * @endcode
+ */
+#define STRINGIZE(EXPRESSION) (static_cast<std::ostringstream&>(Stringize() << EXPRESSION).str())
+
+/**
+ * Helper class for STRINGIZE() macro. Ideally the body of
+ * STRINGIZE(EXPRESSION) would look something like this:
+ * @code
+ * (std::ostringstream() << EXPRESSION).str()
+ * @endcode
+ * That doesn't work because each of the relevant operator<<() functions
+ * accepts a non-const std::ostream&, to which you can't pass a temp instance
+ * of std::ostringstream. Stringize plays the necessary const tricks to make
+ * the whole thing work.
+ */
+class Stringize
+{
+public:
+    /**
+     * This is the essence of Stringize. The leftmost << operator (the one
+     * coded in the STRINGIZE() macro) engages this operator<<() const method
+     * on the temp Stringize instance. Every other << operator (ones embedded
+     * in EXPRESSION) simply sees the std::ostream& returned by the first one.
+     *
+     * Finally, the STRINGIZE() macro downcasts that std::ostream& to
+     * std::ostringstream&.
+     */
+    template <typename T>
+    std::ostream& operator<<(const T& item) const
+    {
+        mOut << item;
+        return mOut;
+    }
+
+private:
+    mutable std::ostringstream mOut;
+};
+
+#endif /* ! defined(LL_STRINGIZE_H) */