Changeset 2270

Timestamp:

Jun 14, 2010, 6:05:59 AM (13 years ago)

Author:

Peter

Message:

is<T> and convert<T> is very similar so rather than duplicating the code let them call a private function. Optimize this function by avoiding calls to is_nan and friends. There is no need to check for is_nan (and friends) if the conversion works. Therefore, and since conversion is expected to most of the time, it is better to try conversion first and then only at failure check if the string is nan, inf or similar.

File:

• trunk/yat/utility/utility.h (modified) (4 diffs)

trunk/yat/utility/utility.h

@@ -8 +8 @@
   Copyright (C) 2006 Jari Häkkinen
   Copyright (C) 2007, 2008 Jari Häkkinen, Peter Johansson
-  Copyright (C) 2009 Peter Johansson
+  Copyright (C) 2009, 2010 Peter Johansson
 
   This file is part of the yat library, http://dev.thep.lu.se/yat
@@ -183 +183 @@
 // private namespace
 namespace detail {
+
+  /**
+     \brief convert s to t
+
+     used in function is<T> and convert<T>
+
+     \return true if conversion was successful
+
+     \internal
+   */
+  template<typename T>
+  bool convert(const std::string& s, T& t);
+
   /**
      Functor used in load function
@@ -249 +262 @@
   T convert(const std::string& s)
   {
-    if (is_nan(s))
-      return std::numeric_limits<T>::quiet_NaN();
-    if (is_equal(s, "inf"))
-      return std::numeric_limits<T>::infinity();
-    if (is_equal(s, "-inf")) {
-      if (std::numeric_limits<T>::is_signed)
-        return -std::numeric_limits<T>::infinity();
-      else
-        throw runtime_error(std::string("yat::utility::convert(\"")+s+
-                            std::string("\"): type is unsigned") );
-    }
-    std::stringstream ss(s);
-    T a;
-    ss >> a;
-    bool ok = true;
-    if(ss.fail()) 
-      ok = false;
-    // Check that nothing is left on stream
-    std::string b;
-    ss >> b;
-    if (!b.empty() || !ok)
+    T result;
+    if (!detail::convert(s, result))
       throw runtime_error(std::string("yat::utility::convert(\"")+s+
                           std::string("\")"));
-    return a;
-  }
+    return result;
+  }
+
 
   template<typename T>
   bool is(const std::string& s)
   {
-    if (is_nan(s))
-      return std::numeric_limits<T>::has_quiet_NaN;
-    if (is_equal(s, "inf"))
-      return std::numeric_limits<T>::has_infinity;
-    if (is_equal(s, "-inf"))
-      return std::numeric_limits<T>::has_infinity && 
-        std::numeric_limits<T>::is_signed;
-    std::stringstream ss(s);
-    T a;
-    ss >> a;
-    if(ss.fail())
-      return false;
-    // Check that nothing is left on stream
-    std::string b;
-    ss >> b;
-    return b.empty();
-  }
+    T tmp;
+    return detail::convert(s, tmp);
+  }
+
 
   template<typename T>
@@ -347 +329 @@
   }           
 
+
+namespace detail {
+  template<typename T>
+  bool convert(const std::string& s, T& result)
+  {
+    std::istringstream ss(s);
+    ss >> result;
+    if (ss.fail()) {
+      if (is_nan(s)) {
+        result = std::numeric_limits<T>::quiet_NaN();
+        return true;
+      }
+      if (is_equal(s, "inf")) {
+        result = std::numeric_limits<T>::infinity();
+        return true;
+      }
+      if (std::numeric_limits<T>::is_signed && is_equal(s, "-inf")) {
+        result = -std::numeric_limits<T>::infinity();
+        return true;
+      }
+      return false;
+    }
+    // Check that nothing is left on stream
+    std::string b;
+    ss >> b;
+    return b.empty();
+  }
+} // of namespace detail
+
 }}} // of namespace utility, yat, and theplu