Grammar for ANLTR 4 - antlr

Question

I'm trying to develop a grammar to parse a DSL using ANTLR4 (first attempt at using it)
The grammar itself is somewhat similar to SQL in the sense that should
It should be able to parse commands like the following:
select type1.attribute1 type2./xpath_expression[#id='test 1'] type3.* from source1 source2
fromDate 2014-01-12T00:00:00.123456+00:00 toDate 2014-01-13T00:00:00.123456Z
where (type1.attribute2 = "XX" AND
(type1.attribute3 <= "2014-01-12T00:00:00.123456+00:00" OR
type2./another_xpath_expression = "YY"))
EDIT: I've updated the grammar switching CHAR, SYMBOL and DIGIT to fragment as suggested by [lucas_trzesniewski], but I did not manage to get improvements.
Attached is the parse tree as suggested by Terence. I get also in the console the following (I'm getting more confused...):
warning(125): API.g4:16:8: implicit definition of token 'CHAR' in parser
warning(125): API.g4:20:31: implicit definition of token 'SYMBOL' in parser
line 1:12 mismatched input 'p' expecting {'.', NUMBER, CHAR, SYMBOL}
line 1:19 mismatched input 't' expecting {'.', NUMBER, CHAR, SYMBOL}
line 1:27 mismatched input 'm' expecting {'.', NUMBER, CHAR, SYMBOL}
line 1:35 mismatched input '#' expecting {NUMBER, CHAR, SYMBOL}
line 1:58 no viable alternative at input 'm'
line 3:13 no viable alternative at input '(deco.m'
I was able to put together the bulk of the grammar, but it fails to properly match all the tokens, therefore resulting in incorrect parsing depending on the complexity of the input.
By browsing on internet it seems to me that the main reason is down to the lexer selecting the longest matching sequence, but even after several attempts of rewriting lexer and grammar rules I could not achieve a robust set.
Below are my grammar and some test cases.
What would be the correct way to specify the rules? should I use lexer modes ?
GRAMMAR
grammar API;
get : K_SELECT (((element) )+ | '*')
'from' (source )+
( K_FROM_DATE dateTimeOffset )? ( K_TO_DATE dateTimeOffset )?
('where' expr )?
EOF
;
element : qualifier DOT attribute;
qualifier : 'raw' | 'std' | 'deco' ;
attribute : ( word | xpath | '*') ;
word : CHAR (CHAR | NUMBER)*;
xpath : (xpathFragment+);
xpathFragment
: '/' ( DOT | CHAR | NUMBER | SYMBOL )+
| '[' (CHAR | NUMBER | SYMBOL )+ ']'
;
source : ( 'system1' | 'system2' | 'ALL') ; // should be generalised.
date : (NUMBER MINUS NUMBER MINUS NUMBER) ;
time : (NUMBER COLON NUMBER (COLON NUMBER ( DOT NUMBER )?)? ( 'Z' | SIGN (NUMBER COLON NUMBER )));
dateTimeOffset : date 'T' time;
filter : (element OP value) ;
value : QUOTE .+? QUOTE ;
expr
: filter
| '(' expr 'AND' expr ')'
| '(' expr 'OR' expr ')'
;
K_SELECT : 'select';
K_RANGE : 'range';
K_FROM_DATE : 'fromDate';
K_TO_DATE : 'toDate' ;
QUOTE : '"' ;
MINUS : '-';
SIGN : '+' | '-';
COLON : ':';
COMMA : ',';
DOT : '.';
OP : '=' | '<' | '<=' | '>' | '>=' | '!=';
NUMBER : DIGIT+;
fragment DIGIT : ('0'..'9');
fragment CHAR : [a-z] | [A-Z] ;
fragment SYMBOL : '#' | [-_=] | '\'' | '/' | '\\' ;
WS : [ \t\r\n]+ -> skip ;
NONWS : ~[ \t\r\n];
TEST 1
select raw./priobj/tradeid/margin[#id='222'] deco.* deco.marginType from system1 system2
fromDate 2014-01-12T00:00:00.123456+00:00 toDate 2014-01-13T00:00:00.123456Z
where ( deco.marginType >= "MV" AND ( ( raw.CretSysInst = "RMS_EXODUS" OR deco.ExtSysNum <= "1234" ) OR deco.ExtSysStr = "TEST Spaced" ) )
TEST 2
select * from ALL
TEST 3
select deco./xpath/expr/text() deco./xpath/expr[a='3' and b gt '6] raw.* from ALL where raw.attr3 = "myvalue"
The image shows that my grammar is unable to recognise several parts of the commands
What is a bit puzzling me is that the single parts are instead working properly,
e.g. parsing only the 'expr' as shown by the tree below

Answer 1

That kind of thing: word : (CHAR (CHAR | NUMBER)+); is indeed a job for the lexer, not the parser.
This: DIGIT : ('0'..'9'); should be a fragment. Same goes for this: CHAR : [a-z] | [A-Z] ;. That way, you could write NUMBER : CHAR+;, and WORD: CHAR (CHAR | NUMBER)*;
The reason is simple: you want to deal with meaningful tokens in your parser, not with parts of words. Think of the lexer as the thing that will "cut" the input text at meaningful points. Later on, you want to process full words, not individual characters. So think about where is it most meaningful to make those cuts.
Now, as the ANTLR master has pointed out, to debug your problem, dump the parse tree and see what goes on.