/**
* Checks if this NFA matches the specified input text. The
* matching will be performed from position zero (0) in the
* buffer. This method will not read any characters from the
* stream, just peek ahead.
*
* @param buffer the input buffer to check
* @param match the token match to update
*
* @return the number of characters matched, or
* zero (0) if no match was found
*
* @throws IOException if an I/O error occurred
*/
public int Match(ReaderBuffer buffer, TokenMatch match)
{
int length = 0;
int pos = 1;
int peekChar;
NFAState state;
// The first step of the match loop has been unrolled and
// optimized for performance below.
queue.Clear();
peekChar = buffer.Peek(0);
if (0 <= peekChar && peekChar < 128)
{
state = initialChar[peekChar];
if (state != null)
{
queue.AddLast(state);
}
}
if (peekChar >= 0)
{
initial.MatchTransitions((char)peekChar, queue, true);
}
queue.MarkEnd();
peekChar = buffer.Peek(1);
// The remaining match loop processes all subsequent states
while (!queue.Empty)
{
if (queue.Marked)
{
pos++;
peekChar = buffer.Peek(pos);
queue.MarkEnd();
}
state = queue.RemoveFirst();
if (state.value != null)
{
match.Update(pos, state.value);
}
if (peekChar >= 0)
{
state.MatchTransitions((char)peekChar, queue, false);
}
}
return(length);
}
/**
* Adds all the epsilon transition targets to the specified
* queue.
*
* @param queue the state queue
*/
public void MatchEmpty(NFAStateQueue queue)
{
NFATransition trans;
NFAState target;
for (int i = 0; i < outgoing.Length; i++)
{
trans = outgoing[i];
if (trans is NFAEpsilonTransition)
{
target = trans.state;
queue.AddLast(target);
if (target.epsilonOut)
{
target.MatchEmpty(queue);
}
}
}
}
/**
* Attempts a match on each of the transitions leading from
* this state. If a match is found, its state will be added
* to the queue. If the initial match flag is set, epsilon
* transitions will also be matched (and their targets called
* recursively).
*
* @param ch the character to match
* @param queue the state queue
* @param initial the initial match flag
*/
public void MatchTransitions(char ch, NFAStateQueue queue, bool initial)
{
NFATransition trans;
NFAState target;
for (int i = 0; i < outgoing.Length; i++)
{
trans = outgoing[i];
target = trans.state;
if (initial && trans is NFAEpsilonTransition)
{
target.MatchTransitions(ch, queue, true);
}
else if (trans.Match(ch))
{
queue.AddLast(target);
if (target.epsilonOut)
{
target.MatchEmpty(queue);
}
}
}
}
/**
* Attempts a match on each of the transitions leading from
* this state. If a match is found, its state will be added
* to the queue. If the initial match flag is set, epsilon
* transitions will also be matched (and their targets called
* recursively).
*
* @param ch the character to match
* @param queue the state queue
* @param initial the initial match flag
*/
public void MatchTransitions(char ch, NFAStateQueue queue, bool initial)
{
NFATransition trans;
NFAState target;
for (int i = 0; i < outgoing.Length; i++) {
trans = outgoing[i];
target = trans.state;
if (initial && trans is NFAEpsilonTransition) {
target.MatchTransitions(ch, queue, true);
} else if (trans.Match(ch)) {
queue.AddLast(target);
if (target.epsilonOut) {
target.MatchEmpty(queue);
}
}
}
}
/**
* Adds all the epsilon transition targets to the specified
* queue.
*
* @param queue the state queue
*/
public void MatchEmpty(NFAStateQueue queue)
{
NFATransition trans;
NFAState target;
for (int i = 0; i < outgoing.Length; i++) {
trans = outgoing[i];
if (trans is NFAEpsilonTransition) {
target = trans.state;
queue.AddLast(target);
if (target.epsilonOut) {
target.MatchEmpty(queue);
}
}
}
}
