A source of characters for an ANTLR lexer
public static final int EOF = -1;
For infinite streams, you don't need this; primarily I'm providing
a useful interface for action code. Just make sure actions don't
use this on streams that don't support it.
Get the ith character of lookahead. This is the same usually as
LA(i). This will be used for labels in the generated
lexer code. I'd prefer to return a char here type-wise, but it's
probably better to be 32-bit clean and be consistent with LA.
ANTLR tracks the line information automatically
Because this stream can rewind, we need to be able to reset the line
The index of the character relative to the beginning of the line 0..n-1