adds cursor control ANSI escape codes

[wassup05]

The PR adds cursor control ANSI escape codes as a separate module stdlib_ansi_cursor

This was brought up scarcely in #229 but was not really discussed.

Functions added are

1. move_to(x,y)
2. move_to_column(x)
3. move_<direction> where <direction> is any one of up, down, left, right
4. A couple of constants for clearning the terminal, clearning a line and it's different variants

Motivation

There is already a module stdlib_ansi for ANSI escape codes of foreground, background colors and the different styles... If a person finds the use for such module it is very probable that he will also at some point want to control the cursor position too, to let's say, implement a custom loading animation or for elegant management of terminal output

Side note

I chose to make it a different module because of the difference in approach between the two, the functions in this module talk in terms of strings whereas stdlib_ansi has a whole type surrounding it and also because you won't need to add the cursor_ to all the functions to make it more readable... But I don't really see a problem in merging the two too...

Edit: This is my first attempt at contributing here and I am not sure about who I am supposed to ask for feedback.. Could you guide me regarding this @perazz @jalvesz (I figured as you were the most active right now, hence pinging you would be appropriate)

[jvdp1]

Thank you @wassup05 for this PR. It sounds like a good start. I left a few comments.

[jvdp1]

Could this be considered as a submodule of the module stdlib_ansi?

[wassup05]

Thank you for reviewing!

It could be, but I thought separating it would be better since stdlib_ansi revolves around it's own derived type whereas this doesn't... I'm open to either way though

[jvdp1]

Is this the same for all OS?

[wassup05]

Yes, It's more of a terminal thing than an OS thing.. But almost all of the modern terminals support these ansi codes

[jvdp1]

Could some of these functions be elemental?

[wassup05]

They could be made so, But I don't think it's worth it since I don't see anyone using it like that

[perazz]

Nice work @wassup05, thank you. I'm no expert on ANSI terminal handling so I will add some of my thoughts here.

• The stdlib_ansi module has a derived type for ANSI escape codes:

stdlib/src/stdlib_ansi.f90

Lines 23 to 31 in 7511064

	type :: ansi_code
	private
	!> Style descriptor
	integer(i1) :: style = -1_i1
	!> Background color descriptor
	integer(i1) :: bg = -1_i1
	!> Foreground color descriptor
	integer(i1) :: fg = -1_i1
	end type ansi_code

If the terminal handling codes provided here match the same pattern, I believe it would be better to uniform their handling with that of the module, and make them type(ansi_code) as well.

• Testing and examples are hard with console handling. However, I think it would be very useful to have examples that show some console interaction with these functions (for example, draw a box on the terminal, or something like that).

[wassup05]

Thanks for replying, @perazz !

When I started working on this, I thought of ways to integrate the two but couldn't really find any such way... As these are more action oriented whereas those of ansi_type were more of like changing the properties of the text being printed

Regarding examples... I added an example in the recent commit which basically draws a blue box on the screen using a subroutine draw_box, whose width, height and the position (line, column) were it is drawn can be changed.. I added the link to it in the spec as well

Please let me know what you think about it