new method: makeStringSafeForPropertyName, replaces invalid chars

simgear/misc/strutils.cxx

@@ -267,6 +267,38 @@ namespace simgear {
 	    return do_strip( s, BOTHSTRIP );
 	}
 
+    string makeStringSafeForPropertyName(const std::string& str)
+    {
+        // This function replaces all characters in 'str' that are not
+        // alphanumeric or '-'.
+        // TODO: make the function multibyte safe.
+        string res = str;
+
+        int index = 0;
+        for (char& c : res) {
+            if (!std::isalpha(c) && !std::isdigit(c) && c != '-') {
+                switch (c) {
+                case ' ':
+                case '\t':
+                case '\n':
+                case '\r':
+                case '_':
+                case '.':
+                case '/':
+                case '\\':
+                    res[index] = '-';
+                    break;
+                default:
+                    res[index] = '_';
+                    SG_LOG(SG_GENERAL, SG_WARN, "makeStringSafeForPropertyName: Modified '" << str << "' to '" << res << "'");
+                }
+            }
+            index++;
+        }
+
+        return res;
+    }
+
         void
         stripTrailingNewlines_inplace(string& s)
         {

simgear/misc/strutils.hxx

@@ -75,7 +75,9 @@ namespace simgear {
 	std::string rstrip( const std::string& s );
 	std::string strip( const std::string& s );
 
-	/**
+    std::string makeStringSafeForPropertyName(const std::string& str);
+
+    /**
          * Return a new string with any trailing \\r and \\n characters removed.
          * Typically useful to clean a CR-terminated line obtained from
          * std::getline() which, upon reading CRLF (\\r\\n), discards the Line

simgear/misc/strutils_test.cxx

@@ -737,6 +737,11 @@ void testDecodeHex()
     SG_VERIFY(decoded == data1);
 }
 
+void test_makeStringSafeForPropertyName()
+{
+    SG_CHECK_EQUAL(strutils::makeStringSafeForPropertyName(" ABC/01234\t:\\\"_*$"), "-ABC-01234-_-_-__");
+}
+
 int main(int argc, char* argv[])
 {
     test_strip();
@@ -761,6 +766,7 @@ int main(int argc, char* argv[])
     test_formatGeod();
     test_iequals();
     testDecodeHex();
-    
+    test_makeStringSafeForPropertyName();
+
     return EXIT_SUCCESS;
 }