Support short float_repr_style

Author: otethal

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/BuiltinConstructors.java

@@ -1024,8 +1024,10 @@ private double convertStringToDouble(String str) {
             try {
                 // Double.valueOf allows format specifier ("d" or "f") at the end
                 String lowSval = sval.toLowerCase(Locale.ENGLISH);
-                if (lowSval.equals("nan") || lowSval.equals("+nan") || lowSval.equals("-nan")) {
+                if (lowSval.equals("nan") || lowSval.equals("+nan")) {
                     return Double.NaN;
+                } else if (lowSval.equals("-nan")) {
+                    return Math.copySign(Double.NaN, -1);
                 } else if (lowSval.equals("inf") || lowSval.equals("+inf") || lowSval.equals("infinity") || lowSval.equals("+infinity")) {
                     return Double.POSITIVE_INFINITY;
                 } else if (lowSval.equals("-inf") || lowSval.equals("-infinity")) {

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/floats/FloatBuiltins.java

@@ -941,8 +941,8 @@ private static double op(double x, long n) {
                 return Math.copySign(0.0, x);
             } else {
                 // We have to work it out properly.
-                BigDecimal xx = BigDecimal.valueOf(x);
-                BigDecimal rr = xx.setScale((int) n, RoundingMode.HALF_UP);
+                BigDecimal xx = new BigDecimal(x);
+                BigDecimal rr = xx.setScale((int) n, RoundingMode.HALF_EVEN);
                 return rr.doubleValue();
             }
         }

graalpython/lib-graalpython/sys.py

@@ -104,6 +104,8 @@ def make_float_info_class():
 float_info = make_float_info_class()(float_info)
 del make_float_info_class
 
+float_repr_style = 'short'
+
 def make_int_info_class():
     from _descriptor import make_named_tuple_class
     return make_named_tuple_class(