Add support for nvim snippet engine (vim.snippet) (#164)

* doc: Add reference to `:h vim.snippet`
* doc: Update docs

---------

Co-authored-by: danymat <d.danymat@gmail.com>

lua/neogen/init.lua

@@ -241,6 +241,8 @@ end
 ---
 --- Note: We will only document `major` and `minor` versions, not `patch` ones. (only X and Y in X.Y.z)
 ---
+--- ## 2.16.0~
+---   - Add support for `nvim` snippet engine (default nvim snippet engine) ! (see |neogen-snippet-integration|)
 --- ## 2.15.0~
 ---   - Google docstrings now include "Yields:", whenever possible
 --- ## 2.14.0~
@@ -299,7 +301,7 @@ end
 ---     with multiple annotation conventions.
 ---@tag neogen-changelog
 ---@toc_entry Changes in neogen plugin
-neogen.version = "2.15.3"
+neogen.version = "2.16.0"
 --minidoc_afterlines_end
 
 return neogen

lua/neogen/snippet.lua

@@ -13,6 +13,7 @@ local conf = require("neogen.config").get()
 --- - `"luasnip"` (https://github.com/L3MON4D3/LuaSnip)
 --- - `"snippy"` (https://github.com/dcampos/nvim-snippy)
 --- - `"vsnip"` (https://github.com/hrsh7th/vim-vsnip)
+--- - `"nvim"` (`:h vim.snippet`)
 ---
 --- If you want to customize the placeholders, you can use `placeholders_text` option:
 --- >
@@ -130,4 +131,16 @@ snippet.engines.vsnip = function(snip, pos)
     vim.fn["vsnip#anonymous"](snip)
 end
 
+--- Expand snippet for vim.snippet engine
+---@param snip string the snippet to expand
+---@param pos table a tuple of row, col
+---@private
+snippet.engines.nvim = function(snip, pos)
+    local row, _ = unpack(pos)
+    vim.api.nvim_buf_set_lines(0, row, row, true, { "" })
+    vim.api.nvim_win_set_cursor(0, { row + 1, 0 })
+    snip = table.concat(snip, "\n")
+    vim.snippet.expand(snip)
+end
+
 return snippet