[cfe-dev] matcher acting wierd,imho

[Aaron Ballman via cfe-dev]

On Mon, Nov 7, 2016 at 4:18 PM, Farzad Sadeghi <thabogre at gmail.com> wrote:
> The AST dump says that the "else if" is treated as an "if" plus an
> "else" which are both children of the first "if".
> Also another Question. How can I match an ifStmt that has an "else if"
> but no "else" at the end?

I think what you want is:

ifStmt(hasElse(ifStmt().bind("else if")),
unless(hasDescendant(ifStmt(hasElse(unless(ifStmt()))))))

Roughly, match an if statement that has an else if statement, unless
one of the descendants is an if statement that has an else clause that
is not an else if statement.

~Aaron

>
> On 11/7/16, Aaron Ballman <aaron at aaronballman.com> wrote:
>> On Mon, Nov 7, 2016 at 4:02 PM, Farzad Sadeghi <thabogre at gmail.com> wrote:
>>> thank you. that actually solves my problem but still doesnt explain
>>> why the matcher i wrote wasnt matching anything at all.
>>> hasDescendant(ifStmt()) is true for the first "if".
>>> hasElse(anything()) is also true and unless(hasAncestor(ifStmt())) is
>>> also true. and theyre all arguments to a "allOf()" so technically the
>>> first "if" should be matched and binded by root. am i mistaken
>>> somewhere?
>>
>> I've not checked out the behavior of your matcher in the debugger, but
>> what I am guessing is:
>>
>> ifStmt( allOf( hasDescendant(ifStmt()), hasElse(anything()),
>> unless(hasAncestor(ifStmt())) ) )
>>
>> I think that this does not match the top-level if statement because
>> hasDescendant(ifStmt()) will not be satisfied -- the top-level if
>> statement has no sub statements that are also an if statement. It
>> does, however, have a sub statement that is an else statement. I
>> notice that the matcher does match the top-level if statement when you
>> remove the hasDescendant() bit from the query, FWIW.
>>
>> ~Aaron
>>
>>>
>>> On 11/7/16, Aaron Ballman <aaron at aaronballman.com> wrote:
>>>> On Mon, Nov 7, 2016 at 4:03 AM, Farzad Sadeghi via cfe-dev
>>>> <cfe-dev at lists.llvm.org> wrote:
>>>>> I have  a simple `if-else if` code I'm trying to match but clang-query
>>>>> or clang itself match nothing.
>>>>> here's the C code:
>>>>> void myfunc (void)
>>>>> {
>>>>>         int a = 0U;
>>>>>         int b = 10U;
>>>>>
>>>>>         if (a == b)
>>>>>         {
>>>>>                 a++;
>>>>>         }
>>>>>         else if (a > b )
>>>>>         {
>>>>>                 b++;
>>>>>         }
>>>>>
>>>>> }
>>>>>
>>>>> and this is my matcher:
>>>>> ifStmt( allOf( hasDescendant(ifStmt()), hasElse(anything()) ,
>>>>> unless(hasAncestor(ifStmt())) ) )
>>>>>
>>>>> clang-query and clang don't match anything. Am i assuming wrong that I
>>>>> should get one match or I'm misunderstanding something here?
>>>>
>>>> I think the matcher you may want is:
>>>>
>>>> clang-query> m ifStmt(hasElse(ifStmt().bind("else if")))
>>>>
>>>> Match #1:
>>>>
>>>> E:\Desktop\test.c:10:14: note: "else if" binds here
>>>>         else if (a > b )
>>>>              ^~~~~~~~~~~
>>>> E:\Desktop\test.c:6:9: note: "root" binds here
>>>>         if (a == b)
>>>>         ^~~~~~~~~~~
>>>> 1 match.
>>>>
>>>> However, it depends on what code pattern you're trying to match. This
>>>> matcher assumes you're looking for else if statements (which "else if"
>>>> binds to, while "root" binds to the if statement that the else
>>>> statement matches).
>>>>
>>>> ~Aaron
>>>>
>>>>>
>>>>> --
>>>>> Farzad Sadeghi
>>>>> _______________________________________________
>>>>> cfe-dev mailing list
>>>>> cfe-dev at lists.llvm.org
>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>>
>>>
>>>
>>> --
>>> Farzad Sadeghi
>>
>
>
> --
> Farzad Sadeghi