ANTLR4 : no viable alternative at input error

Question

I created a sample grammer and generated java source codes and compile them and executed my sample grammer but I got an error like the below.

C:\devEnvironments\antlr>java org.antlr.v4.runtime.misc.TestRig mytest.RuleTest
column_spec -tree
aaa.bbb.ccc
^Z
line 1:0 no viable alternative at input 'aaa.bbb.ccc\r\n'
(column_spec aaa.bbb.ccc\r\n)

The following is my rule source code.

grammar RuleTest;

@header {
package mytest;
}


column_spec:
    ( ( schema_name DOT )? table_name DOT )? column_name ;

ID: 
    ( 'A'..'Z' | 'a'..'z' | '_' | '$') ( 'A'..'Z' | 'a'..'z' | '_' | '$' | '0'..'9' )*
;

// identifiers ---  http://dev.mysql.com/doc/refman/5.6/en/identifiers.html --------------
schema_name         : ID;
table_name          : ID;
engine_name         : ID;
column_name         : ID;
view_name           : ID;
parser_name         : ID;
index_name          : ID;
partition_name          : ID;
partition_logical_name      : ID;
constraint_symbol_name      : ID;
foreign_key_symbol_name     : ID;
collation_name          : ID;
event_name          : ID;
user_name           : ID;
function_name           : ID;
procedure_name          : ID;
server_name         : ID;
wrapper_name            : ID;
alias               : ( AS_SYM )? ANY_STRING;

ANY_STRING:
    ~(' ')+;

DOT : '.' ;
AS_SYM              : 'as';

WS  : [ \t\r\n]+ -> skip ;

I don't know why '\r', '\n' characters are not skipped and why this error happens? I used antlr 4.4 version.

Sam Harwell Sam Harwell · Accepted Answer · 2014-09-05T10:57:27

The ANY_STRING lexer rule matches your entire input. Since that's long than the 3 characters matched by the ID rule, it will always have precedence. You need to either remove that rule, or change it so it only matches one character (thus never the longest).

ANY_STRING_CHAR : ~' ';

ANTLR4 : no viable alternative at input error

1 Answers