grammar keywords;

options {
	language=Java;
	k=*;
}

procedureDecl
	: PROCEDURE IDENTIFIER SEMICOLON subroutineBlock 
	;
	
subroutineBlock
	: external SEMICOLON
	| forward SEMICOLON
	| asmBlock SEMICOLON
	;
	
asmBlock
	: assembler SEMICOLON ASM END
	;

external: {input.LT(1).getText().toLowerCase().equals("external")}? IDENTIFIER;
forward: {input.LT(1).getText().toLowerCase().equals("forward")}? IDENTIFIER;
assembler: {input.LT(1).getText().toLowerCase().equals("assembler")}? IDENTIFIER;

SEMICOLON: ';';
PROCEDURE: 'PROCEDURE';
ASM: 'ASM';
BEGIN: 'BEGIN';
END: 'END';
IDENTIFIER: ('a'..'z'|'A'..'Z')+;
WS: (' '|'\r'|'\n')+ {$channel = HIDDEN;};