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.

src/dos/program_autotype.cpp

@@ -83,15 +83,15 @@ bool AUTOTYPE::ReadDoubleArg(const std::string &name,
 	std::string str_value;
 	// Is the user trying to set this flag?
 	if (cmd->FindString(flag, str_value, true)) {
-		double user_value;
 
 		// Can the user's value be parsed?
-		if (str_to_double(str_value, user_value)) {
+		const double user_value = to_finite<double>(str_value);
+		if (std::isfinite(user_value)) {
 			result = true;
 			// Clamp the user's value if needed
 			value = clamp(user_value, min_value, max_value);
 
-			// If we had to clamp the users value, then inform them
+			// Inform them if we had to clamp their value 
 			if (std::fabs(user_value - value) > std::numeric_limits<double>::epsilon())
 				WriteOut("AUTOTYPE: bounding %s value of %.2f to %.2f\n",
 				         name.c_str(), user_value, value);

src/misc/support.cpp

@@ -35,17 +35,6 @@
 #include "support.h"
 #include "video.h"
 
-bool str_to_double(const std::string& input, double &value) {
-    bool result = false;
-    size_t bytes_read = 0;
-    try {
-        value = std::stod(input, &bytes_read);
-        if (bytes_read == input.size())
-            result = true;
-    } catch (std::invalid_argument &) {}
-    return result;
-}
-
 std::string get_basename(const std::string& filename) {
 	// Guard against corner cases: '', '/', '\', 'a'
 	if (filename.length() <= 1)