* range. It stores all the boundary positions it discovers in
* cachedBreakPositions so that we only have to do this work once
* for each time we enter the range.
*/
private void divideUpDictionaryRange(int startPos, int endPos) {
CharacterIterator text = getText();
// the range we're dividing may begin or end with non-dictionary characters
// (i.e., for line breaking, we may have leading or trailing punctuation
// that needs to be kept with the word). Seek from the beginning of the
// range to the first dictionary character
text.setIndex(startPos);
int c = getCurrent();
int category = lookupCategory(c);
while (category == IGNORE || !categoryFlags[category]) {
c = getNext();
category = lookupCategory(c);
}
// initialize. We maintain two stacks: currentBreakPositions contains
// the list of break positions that will be returned if we successfully
// finish traversing the whole range now. possibleBreakPositions lists
// all other possible word ends we've passed along the way. (Whenever
// we reach an error [a sequence of characters that can't begin any word
// in the dictionary], we back up, possibly delete some breaks from
// currentBreakPositions, move a break from possibleBreakPositions
// to currentBreakPositions, and start over from there. This process
// continues in this way until we either successfully make it all the way
// across the range, or exhaust all of our combinations of break
// positions.)
Stack currentBreakPositions = new Stack();
Stack possibleBreakPositions = new Stack();
Vector wrongBreakPositions = new Vector();
// the dictionary is implemented as a trie, which is treated as a state
// machine. -1 represents the end of a legal word. Every word in the
// dictionary is represented by a path from the root node to -1. A path
// that ends in state 0 is an illegal combination of characters.
int state = 0;
// these two variables are used for error handling. We keep track of the
// farthest we've gotten through the range being divided, and the combination
// of breaks that got us that far. If we use up all possible break
// combinations, the text contains an error or a word that's not in the
// dictionary. In this case, we "bless" the break positions that got us the
// farthest as real break positions, and then start over from scratch with
// the character where the error occurred.
int farthestEndPoint = text.getIndex();
Stack bestBreakPositions = null;
// initialize (we always exit the loop with a break statement)
c = getCurrent();
while (true) {
// if we can transition to state "-1" from our current state, we're
// on the last character of a legal word. Push that position onto
// the possible-break-positions stack
if (dictionary.getNextState(state, 0) == -1) {
possibleBreakPositions.push(new Integer(text.getIndex()));
}
// look up the new state to transition to in the dictionary
state = dictionary.getNextStateFromCharacter(state, c);
// if the character we're sitting on causes us to transition to
// the "end of word" state, then it was a non-dictionary character
// and we've successfully traversed the whole range. Drop out
// of the loop.
if (state == -1) {
currentBreakPositions.push(new Integer(text.getIndex()));
break;
}
// if the character we're sitting on causes us to transition to
// the error state, or if we've gone off the end of the range
// without transitioning to the "end of word" state, we've hit
// an error...
else if (state == 0 || text.getIndex() >= endPos) {
// if this is the farthest we've gotten, take note of it in
// case there's an error in the text
if (text.getIndex() > farthestEndPoint) {
farthestEndPoint = text.getIndex();
bestBreakPositions = (Stack)(currentBreakPositions.clone());
}
// wrongBreakPositions is a list of all break positions
// we've tried starting that didn't allow us to traverse
// all the way through the text. Every time we pop a
//break position off of currentBreakPositions, we put it
// into wrongBreakPositions to avoid trying it again later.
// If we make it to this spot, we're either going to back
// up to a break in possibleBreakPositions and try starting
// over from there, or we've exhausted all possible break
// positions and are going to do the fallback procedure.
// This loop prevents us from messing with anything in
// possibleBreakPositions that didn't work as a starting
// point the last time we tried it (this is to prevent a bunch of
// repetitive checks from slowing down some extreme cases)
Integer newStartingSpot = null;
while (!possibleBreakPositions.isEmpty() && wrongBreakPositions.contains(
possibleBreakPositions.peek())) {
possibleBreakPositions.pop();
}
// if we've used up all possible break-position combinations, there's
// an error or an unknown word in the text. In this case, we start
// over, treating the farthest character we've reached as the beginning
// of the range, and "blessing" the break positions that got us that
// far as real break positions
if (possibleBreakPositions.isEmpty()) {
if (bestBreakPositions != null) {
currentBreakPositions = bestBreakPositions;
if (farthestEndPoint < endPos) {
text.setIndex(farthestEndPoint + 1);
}
else {
break;
}
}
else {
if ((currentBreakPositions.size() == 0 ||
((Integer)(currentBreakPositions.peek())).intValue() != text.getIndex())
&& text.getIndex() != startPos) {
currentBreakPositions.push(new Integer(text.getIndex()));
}
getNext();
currentBreakPositions.push(new Integer(text.getIndex()));
}
}
// if we still have more break positions we can try, then promote the
// last break in possibleBreakPositions into currentBreakPositions,
// and get rid of all entries in currentBreakPositions that come after
// it. Then back up to that position and start over from there (i.e.,
// treat that position as the beginning of a new word)
else {
Integer temp = (Integer)possibleBreakPositions.pop();
Object temp2 = null;
while (!currentBreakPositions.isEmpty() && temp.intValue() <
((Integer)currentBreakPositions.peek()).intValue()) {
temp2 = currentBreakPositions.pop();
wrongBreakPositions.addElement(temp2);
}
currentBreakPositions.push(temp);
text.setIndex(((Integer)currentBreakPositions.peek()).intValue());
}
// re-sync "c" for the next go-round, and drop out of the loop if
// we've made it off the end of the range
c = getCurrent();
if (text.getIndex() >= endPos) {
break;
}
}
// if we didn't hit any exceptional conditions on this last iteration,