/**
* Returns the R or S chirality according to the CIP rules, based on the given chirality
* information.
*
* @param container {@link IAtomContainer} to which the <code>stereoCenter</code> belongs.
* @param stereoCenter Chiral center for which the CIP chirality is to be determined as {@link
* ITetrahedralChirality} object.
* @return A {@link CIP_CHIRALITY} value.
*/
public static CIP_CHIRALITY getCIPChirality(
IAtomContainer container, ITetrahedralChirality stereoCenter) {
// the LigancyFourChirality is kind of redundant but we keep for an
// easy way to get the ILigands array
LigancyFourChirality tmp = new LigancyFourChirality(container, stereoCenter);
Stereo stereo = stereoCenter.getStereo();
int parity = permParity(tmp.getLigands());
if (parity == 0) return CIP_CHIRALITY.NONE;
if (parity < 0) stereo = stereo.invert();
if (stereo == Stereo.CLOCKWISE) return CIP_CHIRALITY.R;
if (stereo == Stereo.ANTI_CLOCKWISE) return CIP_CHIRALITY.S;
return CIP_CHIRALITY.NONE;
}