minor fixes for 64 bits and refactor code
diff --git a/src/jsontestrunner/main.cpp b/src/jsontestrunner/main.cpp
index 3452c59..df717ff 100644
--- a/src/jsontestrunner/main.cpp
+++ b/src/jsontestrunner/main.cpp
@@ -335,6 +335,7 @@
     std::cerr << "Unhandled exception:" << std::endl << e.what() << std::endl;
     return 1;
   }
+  return 0;
 }
 
 #if defined(__GNUC__)
diff --git a/src/lib_json/json_writer.cpp b/src/lib_json/json_writer.cpp
index 18e7a42..0dd160e 100644
--- a/src/lib_json/json_writer.cpp
+++ b/src/lib_json/json_writer.cpp
@@ -68,7 +68,7 @@
 
 #if !defined(isnan)
 // IEEE standard states that NaN values will not compare to themselves
-#define isnan(x) (x != x)
+#define isnan(x) ((x) != (x))
 #endif
 
 #if !defined(__APPLE__)
@@ -272,7 +272,7 @@
   result.append("\\u").append(toHex16Bit(ch));
 }
 
-static String valueToQuotedStringN(const char* value, unsigned length,
+static String valueToQuotedStringN(const char* value, size_t length,
                                    bool emitUTF8 = false) {
   if (value == nullptr)
     return "";
@@ -350,7 +350,7 @@
 }
 
 String valueToQuotedString(const char* value) {
-  return valueToQuotedStringN(value, static_cast<unsigned int>(strlen(value)));
+  return valueToQuotedStringN(value, strlen(value));
 }
 
 // Class Writer
@@ -399,7 +399,7 @@
     char const* end;
     bool ok = value.getString(&str, &end);
     if (ok)
-      document_ += valueToQuotedStringN(str, static_cast<unsigned>(end - str));
+      document_ += valueToQuotedStringN(str, static_cast<size_t>(end - str));
     break;
   }
   case booleanValue:
@@ -422,8 +422,7 @@
       const String& name = *it;
       if (it != members.begin())
         document_ += ',';
-      document_ += valueToQuotedStringN(name.data(),
-                                        static_cast<unsigned>(name.length()));
+      document_ += valueToQuotedStringN(name.data(), name.length());
       document_ += yamlCompatibilityEnabled_ ? ": " : ":";
       writeValue(value[name]);
     }
@@ -468,7 +467,7 @@
     char const* end;
     bool ok = value.getString(&str, &end);
     if (ok)
-      pushValue(valueToQuotedStringN(str, static_cast<unsigned>(end - str)));
+      pushValue(valueToQuotedStringN(str, static_cast<size_t>(end - str)));
     else
       pushValue("");
     break;
@@ -509,7 +508,7 @@
 }
 
 void StyledWriter::writeArrayValue(const Value& value) {
-  unsigned size = value.size();
+  size_t size = value.size();
   if (size == 0)
     pushValue("[]");
   else {
@@ -518,7 +517,7 @@
       writeWithIndent("[");
       indent();
       bool hasChildValue = !childValues_.empty();
-      unsigned index = 0;
+      ArrayIndex index = 0;
       for (;;) {
         const Value& childValue = value[index];
         writeCommentBeforeValue(childValue);
@@ -541,7 +540,7 @@
     {
       assert(childValues_.size() == size);
       document_ += "[ ";
-      for (unsigned index = 0; index < size; ++index) {
+      for (size_t index = 0; index < size; ++index) {
         if (index > 0)
           document_ += ", ";
         document_ += childValues_[index];
@@ -686,7 +685,7 @@
     char const* end;
     bool ok = value.getString(&str, &end);
     if (ok)
-      pushValue(valueToQuotedStringN(str, static_cast<unsigned>(end - str)));
+      pushValue(valueToQuotedStringN(str, static_cast<size_t>(end - str)));
     else
       pushValue("");
     break;
@@ -960,8 +959,8 @@
     char const* end;
     bool ok = value.getString(&str, &end);
     if (ok)
-      pushValue(valueToQuotedStringN(str, static_cast<unsigned>(end - str),
-                                     emitUTF8_));
+      pushValue(
+          valueToQuotedStringN(str, static_cast<size_t>(end - str), emitUTF8_));
     else
       pushValue("");
     break;
@@ -984,8 +983,8 @@
         String const& name = *it;
         Value const& childValue = value[name];
         writeCommentBeforeValue(childValue);
-        writeWithIndent(valueToQuotedStringN(
-            name.data(), static_cast<unsigned>(name.length()), emitUTF8_));
+        writeWithIndent(
+            valueToQuotedStringN(name.data(), name.length(), emitUTF8_));
         *sout_ << colonSymbol_;
         writeValue(childValue);
         if (++it == members.end()) {