highlight.g4

    /* This test file tests Kate's ANTLR highlighting
       compilable bt ANTLR although not directly:
       grammar can be alone file for both parser and lexer
       or two files
       This file is merged TestParser.g4 and TestLexer.g4
       this lines also tests regions of multiline comment
    */
    //file TestParser.g4
    parser grammar TestParser;

    options { tokenVocab = TestLexer; }

    // The main entry point for parsing a grammar.

    startRule
         :  (expression | STRING)+ EOF
         ;

    expression
         :  expression PLUS mulExpr
         |  expression MINUS mulExpr
         |  mulExpr
         ;

    mulExpr
        :  mulExpr MUL unaryExpr
        |  mulExpr DIV unaryExpr
        |  unaryExpr
        ;

    unaryExpr
        : atom
        | LPAR expression RPAR
        ;

    atom
        : IDENT
        | number
        ;

    number
        : INT
        | FLOAT
        ;

    //================================
    //file TestLexer.g4

    lexer grammar TestLexer;

    /*'channels' and '{' must be in one line
     to correct highlighting, highlighter can't
     recognize regular expression "(options|tokens|channels)(?=([\s]*{))"
     where apart from \s whitrspaces are end of lines
     */
    channels { OFF_CHANNEL , COMMENT }

    PLUS
        : '+'
        ;

    MINUS
        : '-'
        ;

    MUL
        : '*'
        ;

    DIV
        : '/'
        ;

    LPAR
        : '('
        ;

    RPAR
        : ')'
        ;

    IDENT
        :   Nondigit
            (   Nondigit
            |   Digit
            )*
        ;

    fragment
    Digit
        :   [0-9]
        ;

    fragment
    NonzeroDigit
        :   [1-9]
        ;

    fragment
    Nondigit
        :   [a-zA-Z_]
        ;

    Sign
        :   '+' | '-'
        ;

    INT
        :  Sign? (NonzeroDigit Digit* | '0')
        ;

    fragment
    DigitSequence
        :   Digit+
        ;

    fragment
    ExponentPart
        :   [eE] Sign? DigitSequence
        ;

    fragment
    FractionalConstant
        :   DigitSequence? '.' DigitSequence
        |   DigitSequence '.'
        ;

    FLOAT
        :   (FractionalConstant ExponentPart? | DigitSequence ExponentPart)
        ;

    fragment
    EscapeSequence
        :   '\\' ['"?abfnrtvhe\\]
        ;

    //between [] is charset , test escape \
    fragment
    SChar
        :   ~["\\\r\n]
        |   EscapeSequence
        ;

    STRING
        :   '"' SChar* '"'
        ;