/** Returns true if the two supplied placements match up (represent a legal board position). */
protected boolean tilesMatch(Placement play1, Placement play2) {
// based on the relative positions of the two placements, determine the "natural" edges to
// be compared (east/west or north/south)
Orient orient1 = play1.loc.directionTo(play2.loc), orient2 = orient1.opposite();
// now rotate those "natural" edges based on the orientations of the placements
orient1 = orient1.rotate(-play1.orient.index);
orient2 = orient2.rotate(-play2.orient.index);
// now make suer those two edges match
return play1.tile.terrain.getEdge(orient1) == play2.tile.terrain.getEdge(orient2);
}
/** Returns the set of board positions where the supplied tile can be legally played. */
public Set<Location> computeLegalPlays(GameTile tile) {
Set<Location> locs = Sets.newHashSet();
// compute the neighbors of all existing tiles
for (Placement play : _plays.values()) {
locs.addAll(play.loc.neighbors());
}
// now go back and remove the occupied tiles
for (Placement play : _plays.values()) {
locs.remove(play.loc);
}
// now remove any position that is not a legal play
OUTER:
for (Iterator<Location> iter = locs.iterator(); iter.hasNext(); ) {
Location pos = iter.next();
ORIENT:
for (Orient orient : Orient.values()) {
Placement play = new Placement(tile, orient, pos);
for (Location npos : pos.neighbors()) {
Placement neighbor = _plays.get(npos);
if (neighbor != null && !tilesMatch(neighbor, play)) {
continue ORIENT; // try next orientation
}
}
continue OUTER; // this orientation matches
}
iter.remove(); // no matches, remove the location
}
return locs;
}
/**
* Computes the legal orientations in which the specified tile can be placed at the supplied
* location.
*/
public List<Orient> computeLegalOrients(GameTile tile, Location loc) {
List<Orient> orients = Lists.newArrayList();
// fetch the neighbors of this tile
List<Placement> neighbors = Lists.newArrayList();
for (Location nloc : loc.neighbors()) {
Placement nplay = _plays.get(nloc);
if (nplay != null) {
neighbors.add(nplay);
}
}
// and validate each candidate orientation against them
ORIENT:
for (Orient orient : Orient.values()) {
Placement play = new Placement(tile, orient, loc);
for (Placement nplay : neighbors) {
if (!tilesMatch(nplay, play)) continue ORIENT;
}
orients.add(orient);
}
return orients;
}