support underscores in literal numbers

Author: timfel

graalpython/com.oracle.graal.python.test/src/tests/test_parser.py

@@ -114,3 +114,10 @@ def newhook(value):
         assert got_value == 6
     finally:
         sys.displayhook = oldhook
+
+
+def test_underscore_in_numbers():
+    assert eval('1_0') == 10
+    assert eval('0b1_1') == 0b11
+    assert eval('0o1_7') == 0o17
+    assert eval('0x1_f') == 0x1f

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/parser/PythonTreeTranslator.java

@@ -791,7 +791,8 @@ public static String unescapeJavaString(String st) {
         return sb.toString();
     }
 
-    private Object parseNumber(String text) {
+    private Object parseNumber(String inputText) {
+        String text = inputText.replace("_", "");
         if (text.endsWith("j") || text.endsWith("J") || text.contains(".")) {
             return parseDottedNumber(text);
         } else {

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/parser/antlr/Python3.g4

@@ -411,7 +411,7 @@ BYTES_LITERAL
 
 /// decimalinteger ::=  nonzerodigit digit* | "0"+
 DECIMAL_INTEGER
- : NON_ZERO_DIGIT DIGIT*
+ : NON_ZERO_DIGIT DECIMAL_DIGIT*
  | '0'+
  ;
 
@@ -541,19 +541,24 @@ fragment DIGIT
  : [0-9]
  ;
 
+/// decimal integer digit    ::=  "0"..."9"
+fragment DECIMAL_DIGIT
+ : [0-9_]
+ ;
+
 /// octdigit       ::=  "0"..."7"
 fragment OCT_DIGIT
- : [0-7]
+ : [0-7_]
  ;
 
 /// hexdigit       ::=  digit | "a"..."f" | "A"..."F"
 fragment HEX_DIGIT
- : [0-9a-fA-F]
+ : [0-9a-fA-F_]
  ;
 
 /// bindigit       ::=  "0" | "1"
 fragment BIN_DIGIT
- : [01]
+ : [01_]
  ;
 
 /// pointfloat    ::=  [intpart] fraction | intpart "."