Activate specific source using a prefix character, thus remove the prefix from the inserted text

[DrKGD]

I'd like to display snippets only by prefixing them using ";", so far i've found someone who already dealt with that

snippets = {
	name = "SNP",
	module = "blink.cmp.sources.snippets",
	score_offset = 95,

	-- THANKS: https://github.com/linkarzu/dotfiles-latest/blob/main/neovim/neobean/lua/plugins/blink-cmp.lua
	should_show_items = function()
		local col = vim.api.nvim_win_get_cursor(0)[2]
		local before_cursor = vim.api.nvim_get_current_line():sub(1, col)
		return before_cursor:match(";%w*$") ~= nil
	end,
}

He also provides a way to "delete" the special prefix character soon after accepting the snippet, but I feel like it is more of a hack and could easily break.

I tried experimenting on my own, but I don't think it is possibile to hijack the item itself to drop the prefix character, all I managed to do is prefixing the displayed label with the character itself

transform_items = function(a, items)
	return vim.iter(items)
		:map(function(item)
			item.label = (";%s"):format(item.label)
			return item
		end)
		:totable()
end

Note that I am not using luasnip as of now (as it is duplicating results) but the builtin snippet source, having friendly-snippets installed. Thanks!

[LamprosPitsillos]

I am also interested in this , any news on this?

[soifou]

Seems related to #1340

[oedotme]

@DrKGD @LamprosPitsillos I got triggering snippets by a semicolon ; working with a combination of should_show_items + get_trigger_characters for the initial trigger, resolve appends the ; to the current completion item - so that the ; is considered part of the snippet prefix and it's replaced automatically once selected/accepted:

opts = {
  sources = {
    providers = {
      snippy = {
        name = 'snippy',
        module = 'utils.snippy',
        min_keyword_length = 1,
        max_items = 8,
        should_show_items = function(ctx) return ctx.trigger.initial_character == ';' end,
        override = {
          get_trigger_characters = function(_) return { ';' } end,
          resolve = function(_, item) item.insertText = ';' .. item.insertText end,
        },
      },
      buffer = {
        min_keyword_length = 2,
        max_items = 8,
        should_show_items = function(ctx) return ctx.trigger.initial_character ~= ';' end,
      },
    },
  },
}

[oedotme]

@DrKGD It's working for me just fine with a partial or full snippet trigger/prefix - maybe it's related to how I have configured the custom source.

Another thing I tried and worked for me as well, is to transform the snippet items adding ; to each - instead of using resolve. This way I believe it's as if you defined all your snippets with ; prefix:

 snippy = {
  name = 'snippy',
  module = 'utils.snippy',
  min_keyword_length = 1,
  max_items = 8,
  should_show_items = function(ctx) return ctx.trigger.initial_character == ';' end,
  override = { get_trigger_characters = function(_) return { ';' } end },
  transform_items = function(_, items)
    for _, item in ipairs(items) do
      item.insertText = ';' .. item.insertText
    end
    return items
  end,
},

[DrKGD]

Mh, also tried that, no luck, here's a summary of what I've observed

1. If I were to configure a resolve method, the given prefix is kept in the buffer
2. If I were to configure transform_items it also prepends a second ;, I suppose the method is called more than once?
3. Not sure if the source is the culprit here, i've tried disabling luasnip and use the default engine only

snippets = {
	preset = 'default',
},

-- ...

providers = {
	snippets = {
		name = "SNP",
	module = "blink.cmp.sources.snippets",
	score_offset = 100,
	min_keyword_length = 1,
	max_items = 10,

        -- I want to be absolutely sure I don't load friendly snippets by mistake
	opts = {
		friendly_snippets = false
	},

	should_show_items = function(ctx)
		return ctx.trigger.initial_character == ';'
	end,

	override = {
		resolve = function(_, item)
			item.insertText = ';' .. item.insertText
		end,

		get_trigger_characters = function(_)
			return { ';' }
		end,
	},
},

Thus I've configured a test snippet only as suggested in the guide

In .config/nvim/snippets/package.json

{
  "name": "personal-snippets",
  "contributes": {
    "snippets": [
      { "language": "c", "path": "./c.json" }
    ]
  }
}

In .config/nvim/snippets/c.json

{
  "foo": {
    "prefix": "foo",
    "body": [
      "test"
    ]
  }
}

I am only getting that one snippet result, but this time the behavior is consistent, thus the snippet always has the ; prefix

4. If I were to update the test snippet by including the prefix, it works just fine

{
  "foo": {
    "prefix": ";foo",
    "body": [
      "test"
    ]
  }
}

I am on version v1.4.1 if that matters

[oedotme]

If I were to configure transform_items it also prepends a second ;, I suppose the method is called more than once?

That's strange, did you keep override.resolve around when you tried transform_items?

[oedotme]

Nevermind, I could reproduce what you described.

[DrKGD]

If I really have to guess, the problem lies somewhere around here...

blink.cmp/lua/blink/cmp/sources/snippets/luasnip.lua

Lines 190 to 202 in 586ee87

	local expand_params = snip:matches(require('luasnip.util.util').get_current_line_to_cursor())
	if expand_params ~= nil then
	if expand_params.clear_region ~= nil then
	clear_region = expand_params.clear_region
	elseif expand_params.trigger ~= nil then
	clear_region = {
	from = { cursor[1], cursor[2] - #expand_params.trigger },
	to = cursor,
	}
	end
	end

By adding a couple of prints right before line 190...

print('item', vim.inspect(item))
print('region_before', vim.inspect(clear_region))
print('params', vim.inspect(expand_params))
print('expand_params', vim.inspect(expand_params))

And this one after line 202...

print('region_before', vim.inspect(clear_region))

And if I were to type out the entire suggestion ";if" (notice the presence of exact = true)

item {
  cursor_column = 1,
  data = {
    show_condition = <function 1>,
    snip_id = 18
  },
  exact = true,
  insertText = ";if",
  insertTextFormat = 1,
  kind = 15,
  label = "if",
  score = 153,
  score_offset = 100,
  sortText = "00000000|||if",
  source_id = "snippets",
  source_name = "SNP",
  textEdit = {
    newText = ";if",
    range = {
      ["end"] = {
        character = 3,
        line = 7
      },
      start = {
        character = 0,
        line = 7
      }
    }
  }
}

region_before {
  from = { 7, 0 },
  to = { 7, 3 }
}

params {
  captures = {},
  trigger = "if"
}

expand {
  captures = {},
  trigger = "if"
}

region_after {
  from = { 7, 1 },
  to = { 7, 3 }
}

The expand.trigger is populated, thus this section updates the clear_region, which range is now wrong

    elseif expand_params.trigger ~= nil then
      clear_region = {
        from = { cursor[1], cursor[2] - #expand_params.trigger },
        to = cursor,
      }
    end

But whenever I have a partial match (again, exact = false this time)

item {
  cursor_column = 1,
  data = {
    show_condition = <function 1>,
    snip_id = 30
  },
  exact = false,
  insertText = ";if",
  insertTextFormat = 1,
  kind = 15,
  label = "if",
  score = 129,
  score_offset = 100,
  sortText = "00000000|||if",
  source_id = "snippets",
  source_name = "SNP",
  textEdit = {
    newText = ";if",
    range = {
      ["end"] = {
        character = 2,
        line = 7
      },
      start = {
        character = 0,
        line = 7
      }
    }
  }
}
region_before {
  from = { 7, 0 },
  to = { 7, 2 }
}
params nil
expand nil
region_after {
  from = { 7, 0 },
  to = { 7, 2 }
}

The clear_region is not getting updated, thus the insertText is adeguately being replaced

I don't really know what really was the intent here and whether or not commenting that code would break something else in the future 🤔