grammar fql;

options {
    backtrack = false;
}

tokens {
    IMPORT = 'IMPORT';
    DEF = 'DEF';
    SELECT = 'SELECT';
    AND = 'AND';
    OR = 'OR';
    NOT = 'NOT';
    IF = 'IF';
    THEN = 'THEN';
    ELSE = 'ELSE';
    CASE = 'CASE';
    MATCH = 'MATCH';
    SWITCH = 'SWITCH';
    AS = 'AS';
    FROM = 'FROM';
    IN = 'IN';
    EXIT = 'EXIT';
    MODULE = 'MODULE';
    PUBLIC = 'PUBLIC';
    TRY = 'TRY';
    CATCH = 'CATCH';
    FILTER = 'FILTER';

    // Operators

    ASSIGN_OP           = ':=';
    EQUAL_OP            = '=';
    GREATER_OP          = '>';
    GREATER_OR_EQUAL_OP = '>=';
    LESS_OP             = '<';
    LESS_OR_EQUAL_OP    = '<=';
    PLUS_OP             = '+';
    INCREMENT_OP        = '++';
    MINUS_OP            = '-';
    DECREMENT_OP        = '--';
    MULTIPLY_OP         = '*';
    DIVIDE_OP           = '/';
}


compilation_unit
    :   module_def
    |   function_def+ ;

module_def
    :   MODULE ident '(' function_def+ ')' ;

function_def
    :   PUBLIC DEF ident '=' function_decl ';'
    |   DEF ident '=' function_decl ';' ;
function_decl
    : select_statement
    | filter_statement ;

select_statement
    :   SELECT field_list FROM source ;

filter_statement
    :   FILTER ident '(' filter_list ')';

field_list
    :   ident ( ',' ident )* ;

filter_list
    :   'FILTERLIST' ;

source  : ident ;

// ---------------------------------------------------------------------------
// L E X E R   G R A M M A R
// ---------------------------------------------------------------------------


WHITESPACE : ( ' ' | '\t' | '\r' | '\n' )+ { $channel = HIDDEN; };

ident   : LETTER ( LETTER | DIGIT )* ;
fragment LETTER : 'A'..'Z' | 'a'..'z' ;
fragment DIGIT : '0'..'9';