private int getComplexity(PsiExpression expression) {
    if (expression == null) return TOO_COMPLEX;
    int complexity = myCache.get(expression);
    if (complexity < 0) {
      complexity = computeComplexity(expression);
      myCache.put(expression, complexity);
    }
    return complexity;
  }
private int getComplexity(PsiExpression expression)