public IntervalSet getSetFromCharSetLiteral(GrammarAST charSetAST) {
String chars = charSetAST.getText();
chars = chars.substring(1, chars.length() - 1);
String cset = '"' + chars + '"';
IntervalSet set = new IntervalSet();
// unescape all valid escape char like \n, leaving escaped dashes as '\-'
// so we can avoid seeing them as '-' range ops.
chars = CharSupport.getStringFromGrammarStringLiteral(cset);
// now make x-y become set of char
int n = chars.length();
for (int i = 0; i < n; i++) {
int c = chars.charAt(i);
if (c == '\\' && (i + 1) < n && chars.charAt(i + 1) == '-') { // \-
set.add('-');
i++;
} else if ((i + 2) < n && chars.charAt(i + 1) == '-') { // range x-y
int x = c;
int y = chars.charAt(i + 2);
if (x <= y) set.add(x, y);
i += 2;
} else {
set.add(c);
}
}
return set;
}
/**
* For a lexer, a string is a sequence of char to match. That is, "fog" is treated as 'f' 'o' 'g'
* not as a single transition in the DFA. Machine== o-'f'->o-'o'->o-'g'->o and has n+1
* states for n characters.
*/
@Override
public Handle stringLiteral(TerminalAST stringLiteralAST) {
String chars = stringLiteralAST.getText();
chars = CharSupport.getStringFromGrammarStringLiteral(chars);
int n = chars.length();
ATNState left = newState(stringLiteralAST);
ATNState prev = left;
ATNState right = null;
for (int i = 0; i < n; i++) {
right = newState(stringLiteralAST);
prev.addTransition(new AtomTransition(right, chars.charAt(i)));
prev = right;
}
stringLiteralAST.atnState = left;
return new Handle(left, right);
}