more work for #611

Author: cowtowncoder

src/main/java/com/fasterxml/jackson/core/json/ReaderBasedJsonParser.java

@@ -757,6 +757,9 @@ public final JsonToken nextToken() throws IOException
              */
             t = _parseNegNumber();
             break;
+        case '.': // [core#61]]
+            t = _parseFloatThatStartsWithPeriod();
+            break;
         case '0':
         case '1':
         case '2':
@@ -950,6 +953,9 @@ public String nextFieldName() throws IOException
         case '-':
             t = _parseNegNumber();
             break;
+        case '.': // [core#61]]
+            t = _parseFloatThatStartsWithPeriod();
+            break;
         case '0':
         case '1':
         case '2':
@@ -1019,6 +1025,9 @@ private final void _isNextTokenNameYes(int i) throws IOException
         case '-':
             _nextToken = _parseNegNumber();
             return;
+        case '.': // [core#61]]
+            _nextToken = _parseFloatThatStartsWithPeriod();
+            return;
         case '0':
         case '1':
         case '2':
@@ -1054,6 +1063,9 @@ protected boolean _isNextTokenNameMaybe(int i, String nameToMatch) throws IOExce
         case '-':
             t = _parseNegNumber();
             break;
+        case '.': // [core#61]]
+            t = _parseFloatThatStartsWithPeriod();
+            break;
         case '0':
         case '1':
         case '2':
@@ -1120,6 +1132,8 @@ private final JsonToken _nextTokenNotInObject(int i) throws IOException
              * it is not allowed per se, it may be erroneously used,
              * and could be indicated by a more specific error message.
              */
+        case '.': // [core#61]]
+            return (_currToken = _parseFloatThatStartsWithPeriod());
         case '0':
         case '1':
         case '2':
@@ -1258,6 +1272,16 @@ public final Boolean nextBooleanValue() throws IOException
     /**********************************************************
      */
 
+    // @since 2.11, [core#611]
+    protected final JsonToken _parseFloatThatStartsWithPeriod() throws IOException
+    {
+        // [core#611]: allow optionally leading decimal point
+        if (!isEnabled(JsonReadFeature.ALLOW_LEADING_DECIMAL_POINT_FOR_NUMBERS.mappedFeature())) {
+            return _handleOddValue('.');
+        }
+        return _parseFloat(INT_PERIOD, _inputPtr-1, _inputPtr, false, 0);
+    }
+
     /**
      * Initial parsing method for number values. It needs to be able
      * to parse enough input to be able to determine whether the