anchor.diff:  
   fragment
   ECHAR
  -    : '\\' ('t' | 'b' | 'n' | 'r' | 'f' | '\\' | '"' | '\'')
  +    : '\\' ( 't' | 'b' | 'n' | 'r' | 'f' | '\\' | '"' | '\'')
  +    ;
  +    		
  +IRI_REF
  +    :(LESS (options{greedy=false;}: IRI_REF_CHARACTERS)* GREATER) =>  LESS (options{greedy=false;}: IRI_REF_CHARACTERS)* GREATER { setText($text.substring(1, $text.length()-1)); }
  +    | LESS { $type = LESS; }
  +    ;
  +    
  +fragment
  +IRI_REF_CHARACTERS
  +    : ~( LESS | GREATER | '"' | OPEN_CURLY_BRACE | CLOSE_CURLY_BRACE | PIPE | INVERSE | '`' | '\\' | ('\u0000'..'\u0020'))
       ;
   
   fragment
  
positive.code:     ;
  
  additiveExpression
      : multiplicativeExpression ( PLUS multiplicativeExpression | MINUS multiplicativeExpression | numericLiteralPositive | numericLiteralNegative )*
      ;
  
  multiplicativeExpression
      : unaryExpression ( ASTERISK unaryExpression | DIVIDE unaryExpression )*
      ;
  
  unaryExpression
      : NOT primaryExpression
      | PLUS primaryExpression
      | MINUS primaryExpression
      | primaryExpression
      ;
  
  primaryExpression
      : brackettedExpression | builtInCall | iriRefOrFunction | rdfLiteral | numericLiteral | booleanLiteral | var
      ;
  
  brackettedExpression
      : OPEN_BRACE expression CLOSE_BRACE
      ;
  
  builtInCall
      : STR OPEN_BRACE expression CLOSE_BRACE
      | LANG OPEN_BRACE expression CLOSE_BRACE
      | LANGMATCHES OPEN_BRACE expression COMMA expression CLOSE_BRACE
      | DATATYPE OPEN_BRACE expression CLOSE_BRACE
      | BOUND OPEN_BRACE var CLOSE_BRACE
      | SAMETERM OPEN_BRACE expression COMMA expression CLOSE_BRACE
      | ISIRI OPEN_BRACE expression CLOSE_BRACE
      | ISURI OPEN_BRACE expression CLOSE_BRACE
      | ISBLANK OPEN_BRACE expression CLOSE_BRACE
      | ISLITERAL OPEN_BRACE expression CLOSE_BRACE
      | regexExpression
      ;
  
  regexExpression
      : REGEX OPEN_BRACE expression COMMA expression ( COMMA expression )? CLOSE_BRACE
      ;
  
  iriRefOrFunction
      : iriRef argList?
      ;
  
negative.code:     ;
  
  conditionalOrExpression
      : conditionalAndExpression ( OR ^conditionalAndExpression )*
      ;
  
  conditionalAndExpression
      : valueLogical ( AND ^valueLogical )*
      ;
  
  valueLogical
  