Validate string to double using std::isfinite

include/support.h

@@ -23,8 +23,11 @@
 
 #include <algorithm>
 #include <cassert>
+#include <cmath>
 #include <cstdio>
 #include <ctype.h>
+#include <limits>
+#include <stdexcept>
 #include <string.h>
 #include <string>
 
@@ -35,8 +38,26 @@
 #define strncasecmp(a, b, n) _strnicmp(a, b, n)
 #endif
 
-// Convert a string to double, returning true or false depending on susccess
-bool str_to_double(const std::string& input, double &value);
+/*
+ *  Converts a string to a finite number (such as float or double).
+ *  Returns the number or quiet_NaN, if it could not be parsed.
+ *  This function does not attemp to capture exceptions that may
+ *  be thrown from std::stod(...)
+ */
+template<typename T>
+T to_finite(const std::string& input) {
+	T result = std::numeric_limits<T>::quiet_NaN();
+	size_t bytes_read = 0;
+	try {
+		const double interim = std::stod(input, &bytes_read);
+		if (!input.empty() && bytes_read == input.size())
+			result = static_cast<T>(interim);
+	}
+	// handle exceptions that stod may throw
+	catch (std::invalid_argument e) {}
+	catch (std::out_of_range e) {}
+	return result;
+}
 
 // Returns the filename with the prior path stripped.
 // Works with both \ and / directory delimeters.