/**
* Return the next monitored token. Test the token following the monitored token. If following is
* another monitored token, save it for the next invocation of nextToken (like a single lookahead
* token) and return it then. If following is unmonitored, nondiscarded (hidden) channel token,
* add it to the monitored token.
*
* <p>Note: EOF must be a monitored Token.
*/
public Token nextToken() throws TokenStreamException {
// handle an initial condition; don't want to get lookahead
// token of this splitter until first call to nextToken
if (LA(1) == null) {
consumeFirst();
}
// we always consume hidden tokens after monitored, thus,
// upon entry LA(1) is a monitored token.
CommonHiddenStreamToken monitored = LA(1);
// point to hidden tokens found during last invocation
monitored.setHiddenBefore(lastHiddenToken);
lastHiddenToken = null;
// Look for hidden tokens, hook them into list emanating
// from the monitored tokens.
consume();
CommonHiddenStreamToken p = monitored;
// while hidden or discarded scarf tokens
while (hideMask.member(LA(1).getType()) || discardMask.member(LA(1).getType())) {
if (hideMask.member(LA(1).getType())) {
// attach the hidden token to the monitored in a chain
// link forwards
p.setHiddenAfter(LA(1));
// link backwards
if (p != monitored) { // hidden cannot point to monitored tokens
LA(1).setHiddenBefore(p);
}
p = lastHiddenToken = LA(1);
}
consume();
}
return monitored;
}
private void consumeFirst() throws TokenStreamException {
consume(); // get first token of input stream
// Handle situation where hidden or discarded tokens
// appear first in input stream
CommonHiddenStreamToken p = null;
// while hidden or discarded scarf tokens
while (hideMask.member(LA(1).getType()) || discardMask.member(LA(1).getType())) {
if (hideMask.member(LA(1).getType())) {
if (p == null) {
p = LA(1);
} else {
p.setHiddenAfter(LA(1));
LA(1).setHiddenBefore(p); // double-link
p = LA(1);
}
lastHiddenToken = p;
if (firstHidden == null) {
firstHidden = p; // record hidden token if first
}
}
consume();
}
}
/** Return a ptr to the hidden token appearing immediately before token t in the input stream. */
public CommonHiddenStreamToken getHiddenBefore(CommonHiddenStreamToken t) {
return t.getHiddenBefore();
}
/** Return a ptr to the hidden token appearing immediately after token t in the input stream. */
public CommonHiddenStreamToken getHiddenAfter(CommonHiddenStreamToken t) {
return t.getHiddenAfter();
}
