/** Return true if the content model could match an empty input stream. */
public boolean empty() {
switch (type) {
case '*':
case '?':
return true;
case '+':
case '|':
for (ContentModel m = (ContentModel) content; m != null; m = m.next) {
if (m.empty()) {
return true;
}
}
return false;
case ',':
case '&':
for (ContentModel m = (ContentModel) content; m != null; m = m.next) {
if (!m.empty()) {
return false;
}
}
return true;
default:
return false;
}
}
/** Return true if the token could potentially be the first token in the input stream. */
public boolean first(Object token) {
switch (type) {
case '*':
case '?':
case '+':
return ((ContentModel) content).first(token);
case ',':
for (ContentModel m = (ContentModel) content; m != null; m = m.next) {
if (m.first(token)) {
return true;
}
if (!m.empty()) {
return false;
}
}
return false;
case '|':
case '&':
{
Element e = (Element) token;
if (valSet == null) {
valSet = new boolean[Element.maxIndex + 1];
val = new boolean[Element.maxIndex + 1];
// All Element instances are created before this ever executes
}
if (valSet[e.index]) {
return val[e.index];
}
for (ContentModel m = (ContentModel) content; m != null; m = m.next) {
if (m.first(token)) {
val[e.index] = true;
break;
}
}
valSet[e.index] = true;
return val[e.index];
}
default:
return (content == token);
// PENDING: refer to comment in ContentModelState
/*
if (content == token) {
return true;
}
Element e = (Element)content;
if (e.omitStart() && e.content != null) {
return e.content.first(token);
}
return false;
*/
}
}