Simplify variable and field regexes

/** An action upon a variable (e.g. usage, definition, declaration) */

public abstract class VariableAction {

    protected static final String VARIABLE_PATTERN = "^([a-zA-Z][a-zA-Z0-9_]*|[_a-zA-Z][a-zA-Z0-9_]+" +

            "|([a-zA-Z][a-zA-Z0-9_]*)([\\.][a-zA-Z][a-zA-Z]*)+)$";

    protected static final String VARIABLE_PATTERN = "([a-zA-Z][a-zA-Z0-9_]*|_[a-zA-Z0-9_]+)";

    protected static final String FIELD_PATTERN = "^" + VARIABLE_PATTERN + "(\\." + VARIABLE_PATTERN + ")*" + "$";

    protected final Expression variable;

    protected final String realName;

    /** Whether this action is performed upon an invented variable,

     * introduced by this library (e.g. the active exception or the returned value). */

    public boolean isSynthetic() {

        return !getVariable().matches(VARIABLE_PATTERN);

        return !getVariable().matches(FIELD_PATTERN);

    }

    public String getVariable() {