[notes]
This is a regression test for #45 "NullPointerException in LexerATNSimulator.execDFA".  https://github.com/antlr/antlr4/issues/46

[type]
Lexer

[grammar]
lexer grammar L;
COLON : ':' ;
PTR : '->' ;
ID : [a-z]+;

[input]
x : x

[output]
[@0,0:0='x',<3>,1:0]
[@1,2:2=':',<1>,1:2]
[@2,4:4='x',<3>,1:4]
[@3,5:4='<EOF>',<-1>,1:5]

[errors]
line 1:1 token recognition error at: ' '
line 1:3 token recognition error at: ' '

