ANTLR error when generating C file using ANTLRWorks - c

Question

I am using ANTLRWorks 1.5 for C (ANTLR 3.5).
I created a lexer and parser file.
When trying to generate code, it returns as error <[18:52:50] error(100): Script.g:57:2: syntax error: antlr: MissingTokenException(inserted [#-1,0:0='<missing EOF>',<-1>,57:1] at options {)>.
Here is the code, please tell what am I missing.
/* ############################## L E X E R ############################ */
grammar Lexer;
options {
language = C;
output = AST; //generating an AST
ASTLabelType = pANTLT3_BASE_TREE; //specifying a tree walker
k=1; // Only 1 lookahead character required
}
// Define string values - either simple unquoted or complex quoted
STRING : ('a'..'z'|'A'..'Z'|'0'..'9'|'_' | '+')+
| ('"' (~'"')* '"');
// Ignore all whitespace
WS :(' '
| '\t'
| '\r' '\n' { newline(); }
| '\n' { newline(); }
)
{ $setType(Token.SKIP); } ;
// TODO:Single-line comment
LINE_COMMENT : '/*' (~('\n'|'\r'))* ('\n'|'\r'('\n')?)?
{ $setType(Token.SKIP); newline(); } ;
// Punctuation
LBRACE : '<';
RBRACE : '>';
SLASH : '/';
EQUALS : '=';
SEMI : ';';
TRIGGER : ('Trigger');
TRIGGERTYPE : ('Fall') SLASH ('Rise')|('Rise') SLASH ('Fall')|('Fall')|('Rise');
DEFAULT : ('Default TimeSet');
TIMESETVAL : ('TSET_')('0..9')*;
/* ############################## P A R S E R ############################ */
grammar Script;
options {
language=C;
output=AST; // Automatically build the AST while parsing
ASTLabelType=pANTLR3_BASE_TREE;
//k=2; // Need lookahead of two for props without keys (to check for the =)
}
/*tokens {
SCRIPT; // Imaginary token inserted at the root of the script
BLOCK; // Imaginary token inserted at the root of a block
COMMAND; // Imaginary token inserted at the root of a command
PROPERTY; // Imaginary token inserted at the root of a property
}*/
/** Rule to parse Trigger line
*/
trigger : TRIGGER EQUALS TRIGGERTYPE SEMI;
/** Rule to parse TimeSet line
*/
timeset : DEFAULT TIMESETVAL;

Answer 1

Your "combined" grammar Lexer only has lexer rules, while when you only define grammar, ANTLR expects at least 1 parser rule.
There are 3 different types of grammars
combined grammar: grammar Foo, generates:
class FooParser extends Parser and
class FooLexer extends Lexer
parser grammar: parser grammar Bar, generates:
class Bar extends Parser
lexer grammar: lexer grammar Baz, generates:
class Baz extends Lexer
So, in your case, change grammar Lexer; into lexer grammar ScriptLexer; (don't name your lexer grammar Lexer since it is the base lexer class in ANTLR!) and import this lexer in your parser grammar:
parser grammar ScriptParser;
import ScriptLexer;
options {
language=C;
output=AST;
ASTLabelType=pANTLR3_BASE_TREE;
}
// ...
Related:
ANTLR3 Wiki: Composite Grammars