[LLVMdev] Some enhancements to ImmutableSet and FoldingSet

[Ted Kremenek]

Actually, neither of these methods are needed for ImmutableSet.   
ImmutableSet already has an 'isEmpty()' method and I have never really  
seen a case where "size()" needs to be explicitly calculated.  If you  
need size() itself, however, this seems like a perfectly valid addition.

On Feb 11, 2009, at 10:57 AM, Ted Kremenek wrote:

>
> On Feb 11, 2009, at 10:54 AM, Bill Wendling wrote:
>
>> On Wed, Feb 11, 2009 at 10:36 AM, Ben Laurie <benl at google.com> wrote:
>>> I needed these for some work I'm doing in clang...
>>>
>> Yes sir! At least this message was informative. One thing:
>>
>> +  int size() const {
>> +    int n = 0;
>> +    for(iterator i = begin() ; i != end() ; ++n, ++i)
>> +      ;
>> +    return n;
>> +  }
>> +  bool empty() const {
>> +    return size() == 0;
>> +  }
>>
>> empty() here isn't a constant-time method. Can you make it's time
>> complexity O(1)?
>>
>> -bw
>
> Bill's right; empty can be made constant time.  e.g.,  "return Root  
> == 0";

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