Support placeholder expansion inside of eval

[thalesmello]

Problem Statement

Some configs snippet expansions I want to do would require expanding the placeholder inside of the eval expression. Would be possible to support that as a feature?

An example of what I'm trying to accomplish, basically to break the line automatically if I hit enter in the $2 placeholder.

snippet f "Anonymous function" i
    function (${1})${2: }$3 `!lua "$2" == "\n" and "\n" or ""`end${0}

Ideas or possible solutions

I think it could maybe be solved by expanding $2 inside the string of the enclosed eval expression, but that would require re-evaluating the eval expression each time the placeholders are updated.

Alternatives you have considered

Alternatively, this could be exposed as a function call:

snippet f "Anonymous function" i
    function (${1})${2: }$3 `!lua require("snippy").expand("$2") == "\n" and "\n" or ""`end${0}

[dcampos]

Looks like an interesting feature to add. Because Snippy uses luaeval() to handle Lua code, we could rely on the "magic" bult-in global _A, that works like this:

luaeval('_A[1] + _A[2]', [40, 2])

So we could have:

snippet f "Anonymous function" i
    function (${1})${2: }$3 `!lua _A[2] == "\n" and "\n" or ""`end${0}

Or something like that.

[roylez]

Could you please explain the _A magic global in more detail? I am not familiar with Lua, and _A cannot be found in the plugin documentation. Additionally, there are not many references to it in the code.

I tried the above example, but it resulted in an attempt to index local '_A' (a nil value) error.

The problem I am encountering is that I need to perform an arithmetic transformation of $1, but it is not obvious how this can be accomplished.

[dcampos]

Could you please explain the _A magic global in more detail? I am not familiar with Lua, and _A cannot be found in the plugin documentation. Additionally, there are not many references to it in the code.

I tried the above example, but it resulted in an attempt to index local '_A' (a nil value) error.

The problem I am encountering is that I need to perform an arithmetic transformation of $1, but it is not obvious how this can be accomplished.

Sorry, my example was just to show how it could work if it was implemented, but currently it doesn't. To learn how _A works, run this from the neovim command line:

:echo luaeval('_A[1] + _A[2]', [2, 3])

For now, if you want to perform an arithmetic transformation of a single tabstop, you could try using a transform tabstop like this:

${1/\d\+/\=submatch(0)*2/}

[roylez]

Awesome. I guess arithmetic transform based on two or more tabstop is still not easily possible but this is good for now.