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From Anton Pevtsov <>
Subject Re: Re: test for 21.strings.capacity
Date Mon, 06 Mar 2006 16:21:10 GMT
The attached file contains the updated version of the test for
I modified the code and pass the tested string length to the widen
function and basic_string ctor to avoid the bug with strings containing
embedded NULs.
But I suspect a bug in the rw_assert formatting output for {#*S}.
The wchar string "abc" is displayed as "a\0b" (maybe the function
dumps each byte, not symbol here).

Btw., maybe it would be useful to move the widen function to rw_char
header (or some another place in the test driver).

With best wishes,
Anton Pevtsov

-----Original Message-----
From: Martin Sebor []
Sent: Sunday, March 05, 2006 01:07
Subject: Re: test for 21.strings.capacity

Anton Pevtsov wrote:

 >> The attached file contains the test for the basic_string methods
 >> described in 21.strings.capacity. Here the same to
 >> 27.stringbuf.virtuals schema is used. But I think we need to implement

 >> our own allocator class for the test purposes to strictly test some
 >> methods (max_size, capacity). Also may be useful to develop some
 >> analogue of the algorithms tests X class to be used instead of char
 >> and wchar_t (according to the standard here may be any POD type).
 >> Martin, what do you think about this?

I agree. Exercising the template with user-defined template arguments in
addition to the default ones is important. The header file named
mychar.h contains a user-defined character type and traits class that
was designed for this purpose. The header myallocator.h defines a custom
allocator that we could use. We need to port these headers to the new
driver first (it should be pretty easy). I also want to rename them to
follow the rw_xxx.h convention.

I made a few improvements to the test and committed it here:

My comments are below.

Btw., I noticed a bug in the test I decided not to fix and let you do it
 :)  The hardocded strings containing embedded NULs do not always seem to
be handled correctly (with my changes in place you will see it if you
run the test with the --trace option). The string object needs to be
initialized using the two-argument ctor.



 >> int traits_eof = -1;

This shouldn't be necessary. AFAIK, basic_string doesn't use EOF for

 >> template <class charT>
 >> struct CharTraits: std::char_traits<charT>
 >> {
 >>     typedef std::char_traits<charT> Base;
 >>     typedef typename Base::int_type int_type;

I think it would be useful to change the int_type here from the default,
say to short or something unusual.

 >>     // override eof() to detect bad assumptions
 >>     static int_type eof () { return traits_eof; }
 >>     static int_type not_eof (int_type c) {
 >>         return c == eof () ? int_type (!c) : c;
 >>     }

This shouldn't be necessary. As I mentioned above, basic_string doesn't
make use of these functions (they're good for I/O).

 >> };
 >> /*********************************************************************
 >> *****/
 >> struct VFun
 >> {
 >>     enum charT { Char, WChar };
 >>     enum Traits { DefaultTraits, UserTraits };
 >>     enum VirtualTag {
 >>         // which virtual function to exercise

Since (unlike basic_stringbuf) basic_string has no virtual functions I
changed the name of the class and of the tag to make more sense.

 >>         size, resize, length, reserve, capacity, max_size, clear,


 >>     };


 >> template <class charT>
 >> void widen (charT *buf, const char *str)

This function will need to take an additional argument -- the length of
string -- to correctly handle embedded NULs.


 >>     rw_assert (should_throw == ex_thrown, 0, line,
 >>                "line %d. basic_string<%s, %s, %s>.resize(%zu%{?},

%#c%{;}) "

 >>                "on \"%s\" should throw == %b, was thrown == %b",
 >>                __LINE__, pfid->cname_, pfid->tname_, "std::allocator",
 >>                nparam, resize2args, chart_param, 0 != str ? str :


 >>                should_throw, ex_thrown);

I changed this and the other statements to use the %{#*S} directive
designed for the formatting of generic basic_string objects. Check it
out, it's quite handy (so handy, in fact, that it exposed the bug I
mentioned above).


 >>     // check the results
 >>     static charT wstr_tmp [long_string_len];
 >>     widen (wstr_tmp, str);

When str contains embedded NULs they are not handled.


 >> void test_size (VFun *pfid)
 >> {
 >>     rw_info (0, 0, 0, "basic_string<%s, %s, %s>::size ()",
 >>              pfid->cname_, pfid->tname_, "std::allocator");
 >>     pfid->vfun_ = VFun::size;

I decided to move this assignment up to the caller for simplicity.

 >> #define TEST(str, size)


 >>     test_string_capacity (pfid, __LINE__, str, sizeof str - 1,


 >>                           0, 0, size, false)


I think it's better (less error-prone) to #undef the macro just before
#defining it so I moved the #undef directives immediately above the


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