anchor.diff:  SHOWPLAN:                              'SHOWPLAN';
   SIGNATURE:                             'SIGNATURE';
   SIMPLE:                                'SIMPLE';
  -SINGLE_USER:                           'SINGLE_USER';
  +SINGLE_USER:                           'SINGLE_USER'; 
   SIZE:                                  'SIZE';
   SMALLINT:                              'SMALLINT';
   SNAPSHOT:                              'SNAPSHOT';
  
positive.code: DOUBLE_QUOTE_ID:    '"' ~'"'+ '"';
  SINGLE_QUOTE:       '\'';
  SQUARE_BRACKET_ID:  '[' ~']'+ ']';
  LOCAL_ID:           '@' ([A-Za-z_$@#0-9] | FullWidthLetter)+;
  DECIMAL:             DEC_DIGIT+;
  ID:                  ( [A-Z_#] | FullWidthLetter) ( [A-Z_#$@0-9] | FullWidthLetter )*;
  QUOTED_URL:          '\''([A-Z][A-Z]+[:]) '//'(([A-Z]+[.]|[A-Z]+)|IPV4_ADDR) [:] DECIMAL '\'';
  
negative.code: fragment DEC_DIGIT:    [0-9];
  
  fragment FullWidthLetter
      : '\u00c0'..'\u00d6' 
      | '\u00d8'..'\u00f6' 
      | '\u00f8'..'\u00ff' 
      | '\u0100'..'\u1fff' 
      | '\u2c00'..'\u2fff' 
      | '\u3040'..'\u318f' 
      | '\u3300'..'\u337f' 
      | '\u3400'..'\u3fff' 
      | '\u4e00'..'\u9fff' 
      | '\ua000'..'\ud7ff' 
      | '\uf900'..'\ufaff' 
      | '\uff00'..'\ufff0'
      // | '\u10000'..'\u1F9FF'  //not support four bytes chars
      // | '\u20000'..'\u2FA1F'
  