STLSoft 1.9.98 changes to stlsoft::split()

As of STLSoft 1.9.98, stlsoft::split() has been enhanced to be able to split into between two and six fragments. Previously you would have use intermediates to split into more fields, as in:

std::string line = "abc|def|ghi|jkl";

stlsoft::string_view dummy1;

stlsoft::string_view dummy2;

stlsoft::string_view field0;

stlsoft::string_view field1;

stlsoft::string_view field2;

stlsoft::string_view field3;

if(stlsoft::split(line, '|', field0, dummy1) &&
   stlsoft::split(dummy1, '|', field1, dummy2) &&
   stlsoft::split(dummy2, '|', field2, field3))
{
  . . . // use fields
} 

Although there's no additional memory allocation here - because we're using string views as the intermediate and final fragment types - it's still hard to follow, and doing three separate split operations.

You can now split directly into up to six fields, as in:

std::string line = "abc|def|ghi|jkl";

stlsoft::string_view field0;

stlsoft::string_view field1;

stlsoft::string_view field2;

stlsoft::string_view field3;

if(stlsoft::split(line, '|', field0, field1, field2, field3))
{
  . . . // use fields
} 

It's marginally more efficient when using string views, and substantially more efficient when using string value types (such as std::string and stlsoft::simple_string). In either cases, it's considerably more transparent.

simple_string evolution

I'm finally putting some time into getting stlsoft::(basic_)simple_string finished - it's only been, er, 6 years. :$

Anyhow, here's the thinking:

1. Round out all the currently-missing std::basic_string equivalency methods, so that it can act as a full functional replacement
   
2. Define its purpose. This is something that has confused STLSoft users over the years.
   
3. Provide compile-time selection of its nature, facilitating user-selected customisations of its implementation
   

The second point can be expressed as two main notions:

• It has a documented footprint, equivalent to a single char*, which is consistent across platforms/architectures/operating systems, allowing, for example, a user to pass a std::vector<stlsoft::simple_string> to a function taking an array of C-style strings
• It is, in some circumstances, more efficient than std::basic_string. Please note that superior efficiency is not a main design feature of the component, nor is it claimed in any general sense.

These changes will be included in forthcoming alpha releases of STLSoft 1.10.