Add CStringArray::join() method

[mikee47]

Available in other languages (python, javascript) this provides an efficient way to concatenate array members.

[what-the-diff]

PR Summary

• Introduction of a Novel Method in CStringArray Class
  A new function called join has been incorporated into the CStringArray class. This function allows arranged items in the array to be conveniently converted into a string separated by a delimiter, which is, by default, a comma. Although the separator is preset to a comma, this can be adjusted depending on the user's preference.

• Addition of Tests for the New Method
  Essential tests have been added to evaluate the performance and correctness of the recently implemented join function. This is crucial to ensure that the method works as expected and doesn't produce unexpected outcomes.

• Improved Code Readability in CStringArray.cpp
  Several formatting adjustments have been made to the CStringArray.cpp file. The goal of these changes is to enhance the readability of the code, making it easier for the developers to understand, manage, and maintain the codebase.

[slaff]

@mikee47 Is there a reason for the separator parameter to be optional? In JavaScript, PHP and Python as far as I can say this parameter is mandatory.

[mikee47]

I hadn't considered PHP but default is same as javascript https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/join.

Python would be ",".join(cs) which is an interesting construction - clearly there cannot be any 'default' in this case. However, to actually implement this efficiently for Sming would require that the array itself does the join. We could add this as a template method to String easily enough:

class String
{
  ...

  template <class Array> String join(const Array& array)
  {
    return array.join(*this);
  }

  ...
};

[mikee47]

I don't know of any C++ STL equivalent for this, though I see Boost has https://www.geeksforgeeks.org/boostalgorithmjoin-in-cpp-library/ https://www.boost.org/doc/libs/1_83_0/doc/html/boost/algorithm/join.html

[mikee47]

to actually implement this efficiently for Sming would require that the array itself does the join

The efficiency here is avoiding reallocations for the returned String as in the general case:

template <class Array> String join(const Array& array, const String& separator)
{
  String s;
  for(auto& e: array) {
    if(s) {
      s += separator;
    }
    s += e;
  }
  return s;
}

This should work for any Vector or other iterable objects with an implicit String() operator. Something that works with HashMaps would also be useful (returning delimited 'name=value' pairs). However the implementation as it stands does not perform any string escaping, for example:

CStringArray cs;
cs.add("first");
cs.add("second,plus,stuff");

Then cs.join() returns "first,second,plus,stuff" as requested. If "first,""second,plus,stuff""" is required that'll have to be done manually. This is same behaviour as python.