syntactic predicates - Upgrading from Antlr 3 to Antlr 4 - antlr3

Question

I have syntactic predicated that I have to convert into the Antlr 4. The grammar is not written my me so I have no idea how to convert them in a meaningful way. These are the main variations of the grammar that I have to convert.
1.
simpleSelector
: elementName
((esPred)=>elementSubsequent)*
| ((esPred)=>elementSubsequent)+
;
esPred
: HASH | DOT | LBRACKET | COLON
;
elementSubsequent
: HASH
| cssClass
| attrib
| pseudo
;
2.
fragment EMS :; // 'em'
fragment EXS :; // 'ex'
fragment LENGTH :; // 'px'. 'cm', 'mm', 'in'. 'pt', 'pc'
fragment ANGLE :; // 'deg', 'rad', 'grad'
fragment TIME :; // 'ms', 's'
fragment FREQ :; // 'khz', 'hz'
fragment DIMENSION :; // nnn'Somethingnotyetinvented'
fragment PERCENTAGE :; // '%'
NUMBER
:(
'0'..'9' ('.' '0'..'9'+)?
| '.' '0'..'9'+
)
(
(E (M|X))=>
E
(
M { $type = EMS; } //action in lexer rule 'NUMBER' must be last element of single outermost alt
| X { $type = EXS; }
)
| (P(X|T|C))=>
P
(
X
| T
| C
)
{ $type = LENGTH; }
| (C M)=>
C M { $type = LENGTH; }
| (M (M|S))=>
M
(
M { $type = LENGTH; }
| S { $type = TIME; }
)
| (I N)=>
I N { $type = LENGTH; }
| (D E G)=>
D E G { $type = ANGLE; }
| (R A D)=>
R A D { $type = ANGLE; }
| (S)=>S { $type = TIME; }
| (K? H Z)=>
K? H Z { $type = FREQ; }
| IDENT { $type = DIMENSION; }
| '%' { $type = PERCENTAGE; }
| // Just a number
)
;
3.
URI : U R L
'('
((WS)=>WS)? (URL|STRING) WS?
')'
;
some guidance is greatly appreciated.
Edit:
Is it as below.
simpleSelector
: elementName
(elementSubsequent)*
| (elementSubsequent)+
;

Answer 1

Syntactic predicates were only used to work around a prediction weakness in ANTLR 3 that is not present in ANTLR 4. You can simply remove them during your transition to ANTLR 4.
Edit:
A syntactic predicate in ANTLR 3 had the following form:
(stuff) =>
Wherever you see that form in your grammar, just remove it. Here's what your second example looks like with the predicates removed.
NUMBER
:(
'0'..'9' ('.' '0'..'9'+)?
| '.' '0'..'9'+
)
(
E
(
M { $type = EMS; }
| X { $type = EXS; }
)
| P
(
X
| T
| C
)
{ $type = LENGTH; }
| C M { $type = LENGTH; }
| M
(
M { $type = LENGTH; }
| S { $type = TIME; }
)
| I N { $type = LENGTH; }
| D E G { $type = ANGLE; }
| R A D { $type = ANGLE; }
| S { $type = TIME; }
| K? H Z { $type = FREQ; }
| IDENT { $type = DIMENSION; }
| '%' { $type = PERCENTAGE; }
| // Just a number
)
;