public ASTNode createAST(IProgressMonitor monitor) {
		SubMonitor subMonitor = SubMonitor.convert(monitor, 1);
		ASTNode result = null;
		try {
			if (this.rawSource == null && this.typeRoot == null) {
				throw new IllegalStateException("source not specified"); //$NON-NLS-1$
			}
			result = internalCreateAST(subMonitor.split(1));
		} finally {
			// reset to defaults to allow reuse (and avoid leaking)
			initializeDefaults();
		}
		return result;
	}