feat: add experimental insert mode virtual markers

* feat: add experimental insert mode virtual markers

Requires nvim nightly (0.10.0+).

doc/snippy.txt

@@ -440,7 +440,7 @@ local_snippet_dir ~
 hl_group ~
     Highlight group used for placeholders.
         Type: `String`
-        Default: nil
+        Default: SnippyPlaceholder
 
 choice_delay ~
     Defines the delay in milliseconds before the choice menu is displayed.
@@ -511,12 +511,32 @@ mappings ~
     | previous            | snippy.mapping.Previous          |
     | cut_text            | snippy.mapping.CutText           |
 
-expand_options~
+expand_options ~
     Add new `option`s to limit triggering in certain scenarios. See
     |snippy-snippet-options|.
         Type: `Table`
         Default: {}
 
+virtual_markers ~
+    Enable virtual text markers that show all available (inactive) tabstops
+    and placeholders.
+        Type: `Table`
+        Default: >lua
+
+        virtual_markers = {
+            enabled = false,
+            -- Marker for all placeholders (non-empty)
+            default = '',
+            -- Marker for all empty tabstops
+            empty = '',
+            -- Marker highlighing
+            hl_group = 'SnippyMarker',
+        }
+<
+    The marker value can contain the following special formatting symbols:
+
+        - `%n`: current stop number.
+
 
 ==============================================================================
 BUFFER OPTIONS                                         *snippy-buffer-options*

lua/snippy/buf.lua

@@ -1,4 +1,5 @@
 local shared = require('snippy.shared')
+local util = require('snippy.util')
 
 local Stop = require('snippy.stop')
 
@@ -24,7 +25,7 @@ setmetatable(M, {
         elseif key == 'stops' then
             self.state().stops = value
         else
-            return rawset(self, key, value)
+            rawset(self, key, value)
         end
     end,
 })
@@ -35,32 +36,48 @@ setmetatable(M, {
 ---@param startcol number
 ---@param endrow number
 ---@param endcol number
----@param right_gravity number
----@param end_right_gravity number
+---@param right_gravity boolean
+---@param end_right_gravity boolean
+---@param current boolean
 ---@return number Extmark identifier
-local function add_mark(id, startrow, startcol, endrow, endcol, right_gravity, end_right_gravity)
-    local mark = api.nvim_buf_set_extmark(0, shared.namespace, startrow, startcol, {
+local function add_mark(id, startrow, startcol, endrow, endcol, right_gravity, end_right_gravity, current, order)
+    local config = shared.config
+    local hl_group = config.hl_group
+    local opts = {
         id = id,
         end_line = endrow,
         end_col = endcol,
-        hl_group = shared.config.hl_group,
+        hl_group = hl_group,
         right_gravity = right_gravity,
         end_right_gravity = end_right_gravity,
-    })
+    }
+    if vim.fn.has('nvim-0.10') == 1 and config.virtual_markers.enabled then
+        if not current and order > 0 then
+            opts.virt_text_pos = 'inline'
+            if startrow == endrow and startcol == endcol then
+                local text = util.expand_virtual_marker(config.virtual_markers.empty, order)
+                opts.virt_text = { { text, config.virtual_markers.hl_group } }
+            else
+                local text = util.expand_virtual_marker(config.virtual_markers.default, order)
+                opts.virt_text = { { text, config.virtual_markers.hl_group } }
+            end
+        end
+    end
+    local mark = api.nvim_buf_set_extmark(0, shared.namespace, startrow, startcol, opts)
     return mark
 end
 
-local function activate_parents(number)
+local function activate_parents(number, current)
     local parents = M.stops[number]:get_parents()
     for _, n in ipairs(parents) do
         local stop = M.state().stops[n]
         local from, to = stop:get_range()
         local mark_id = stop.mark
-        local _ = add_mark(mark_id, from[1], from[2], to[1], to[2], false, true)
+        local _ = add_mark(mark_id, from[1], from[2], to[1], to[2], false, true, current, stop.order)
     end
 end
 
---- Activates a stop (and all its mirrors) by changing its extmark's gravity.
+--- Activates a stop (and all its mirrors) by current its extmark's gravity.
 --- Parents (outer stops) must also be activated.
 ---@param number number Stop number (index)
 local function activate_stop_and_parents(number)
@@ -69,10 +86,22 @@ local function activate_stop_and_parents(number)
         if stop.id == value.id then
             local from, to = stop:get_range()
             local mark_id = stop.mark
-            local _ = add_mark(mark_id, from[1], from[2], to[1], to[2], false, true)
-            activate_parents(n)
+            local _ = add_mark(mark_id, from[1], from[2], to[1], to[2], false, true, n == number, stop.order)
+            activate_parents(n, n == number)
+        end
+    end
+end
+
+--- Gets the ordering number for the next added tabstop.
+---@return integer
+local function next_order()
+    local n = 1
+    for _, stop in ipairs(M.state().stops) do
+        if stop.traversable then
+            n = n + 1
         end
     end
+    return n
 end
 
 --- Mirrors a stop and its parents by number.
@@ -133,7 +162,7 @@ function M.clear_children(stop_num)
 end
 
 function M.state()
-    local bufnr = api.nvim_buf_get_number(0)
+    local bufnr = api.nvim_get_current_buf()
     if not M._state[bufnr] then
         M._state[bufnr] = {
             stops = {},
@@ -158,8 +187,14 @@ function M.add_stop(spec, pos)
     local endrow = spec.endpos[1] - 1
     local endcol = spec.endpos[2]
     local stops = M.state().stops
-    local smark = add_mark(nil, startrow, startcol, endrow, endcol, true, true)
-    table.insert(stops, pos, Stop.new({ id = spec.id, traversable = is_traversable(), mark = smark, spec = spec }))
+    local traversable = is_traversable()
+    local order = traversable and next_order() or -1
+    local smark = add_mark(nil, startrow, startcol, endrow, endcol, true, true, false, order)
+    table.insert(
+        stops,
+        pos,
+        Stop.new({ id = spec.id, order = order, traversable = traversable, mark = smark, spec = spec })
+    )
     M.state().stops = stops
 end
 
@@ -188,7 +223,7 @@ function M.deactivate_stops()
     for _, stop in ipairs(M.state().stops) do
         local from, to = stop:get_range()
         local mark_id = stop.mark
-        local _ = add_mark(mark_id, from[1], from[2], to[1], to[2], true, true)
+        local _ = add_mark(mark_id, from[1], from[2], to[1], to[2], true, true, false, stop.order)
     end
 end
 
@@ -212,7 +247,7 @@ function M.fix_current_stop()
     if new ~= old and current_line:sub(1, #old) == old then
         local stop = M.stops[M.current_stop]
         local from, to = stop:get_range()
-        add_mark(stop.mark, from[1], #old, to[1], to[2], false, true)
+        local _ = add_mark(stop.mark, from[1], #old, to[1], to[2], false, true, true, stop.order)
     end
 end
 

lua/snippy/shared.lua

@@ -25,7 +25,7 @@ end
 local default_config = {
     snippet_dirs = nil,
     local_snippet_dir = '.snippets',
-    hl_group = nil,
+    hl_group = 'SnippyPlaceholder',
     scopes = {},
     mappings = {},
     choice_delay = 100,
@@ -35,6 +35,12 @@ local default_config = {
         enabled = false,
         level = 'debug',
     },
+    virtual_markers = {
+        enabled = false,
+        empty = '',
+        default = '',
+        hl_group = 'SnippyMarker',
+    },
 }
 
 M.get_scopes = get_scopes
@@ -99,6 +105,12 @@ function M.set_config(params)
             end,
         })
     end
+    if params.logging then
+        params.logging = vim.tbl_extend('keep', params.logging, M.config.logging)
+    end
+    if params.virtual_markers then
+        params.virtual_markers = vim.tbl_extend('keep', params.virtual_markers, M.config.virtual_markers)
+    end
     M.config = vim.tbl_extend('force', M.config, params)
 end
 

lua/snippy/stop.lua

@@ -4,13 +4,22 @@ local util = require('snippy.util')
 local api = vim.api
 local fn = vim.fn
 
+---@class Stop
+---@field id number
+---@field order number
+---@field traversable boolean
+---@field mark number
+---@field spec table
 local Stop = {}
 
 function Stop.new(o)
     local self = setmetatable(o, {
         __index = Stop,
         id = -1,
+        order = -1,
+        traversable = false,
         mark = nil,
+        spec = {},
     })
     return self
 end
@@ -22,7 +31,7 @@ function Stop:get_range()
         local endrow, endcol = mark[3].end_row, mark[3].end_col
         return { startrow, startcol }, { endrow, endcol }
     end
-    return nil
+    error('No mark found for stop')
 end
 
 function Stop:get_text()
@@ -45,6 +54,7 @@ end
 
 function Stop:get_before()
     local from, _ = self:get_range()
+    assert(from, 'from should not be nil')
     local current_line = fn.getline(from[1] + 1)
     local pre = current_line:sub(1, from[2])
     return pre

lua/snippy/util.lua

@@ -57,4 +57,11 @@ function M.merge_snippets(current, added)
     return result
 end
 
+function M.expand_virtual_marker(marker_text, number)
+    -- Use %n to insert the stop number
+    local result = marker_text:gsub('([^%%]-)%%n', '%1' .. number)
+    result = result:gsub('%%%%', '%')
+    return result
+end
+
 return M

test/functional/snippy_spec.lua

@@ -905,4 +905,66 @@ describe('Snippy', function()
         exec_lua('snippy.next()')
         eq('ExpandedJumpedFinished', exec_lua([[return Snippy_autocmds]]))
     end)
+
+    it('virtual markers', function()
+        command('set filetype=lua')
+        exec_lua([[snippy.setup({
+            virtual_markers ={
+                enabled = true,
+                default = '>',
+                empty = '|',
+            }
+        })]])
+        exec_lua('snippy.expand_snippet([[local ${1:var} = ${2:val}${0}]])')
+        screen:expect({
+            grid = [[
+          local ^v{3:ar} = >val|                                 |
+          {1:~                                                 }|
+          {1:~                                                 }|
+          {1:~                                                 }|
+          {2:-- SELECT --}                                      |
+        ]],
+        })
+        exec_lua([[snippy.next()]])
+        screen:expect({
+            grid = [[
+          local >var = ^v{3:al}|                                 |
+          {1:~                                                 }|
+          {1:~                                                 }|
+          {1:~                                                 }|
+          {2:-- SELECT --}                                      |
+        ]],
+        })
+    end)
+
+    it('virtual markers with numbers', function()
+        command('set filetype=lua')
+        exec_lua([[snippy.setup({
+            virtual_markers = {
+                enabled = true,
+                default = '%n:>',
+                empty = '%n:|',
+            }
+        })]])
+        exec_lua('snippy.expand_snippet([[local ${1:var} = ${2:val}${0}]])')
+        screen:expect({
+            grid = [[
+          local ^v{3:ar} = 2:>val3:|                             |
+          {1:~                                                 }|
+          {1:~                                                 }|
+          {1:~                                                 }|
+          {2:-- SELECT --}                                      |
+        ]],
+        })
+        exec_lua([[snippy.next()]])
+        screen:expect({
+            grid = [[
+          local 1:>var = ^v{3:al}3:|                             |
+          {1:~                                                 }|
+          {1:~                                                 }|
+          {1:~                                                 }|
+          {2:-- SELECT --}                                      |
+        ]],
+        })
+    end)
 end)