Add extmarks inserter

lua/snippets/inserters/extmarks.lua

@@ -0,0 +1,202 @@
+local api = vim.api
+local U = require("snippets/common")
+
+local ns = api.nvim_create_namespace("")
+
+local M = {}
+
+-- These are user-configurable
+M.marker_with_placeholder_format = "${%d:%s}"
+M.zero_pattern = "$0"
+M.hl_group = "Visual"
+
+local function set_extmark(bufnr, id, line, col, end_line, end_col, hl_group)
+  api.nvim_buf_set_extmark(bufnr, ns, line, col, {
+    id = id,
+    end_line = end_line,
+    end_col = end_col,
+    hl_group = hl_group,
+    right_gravity = false,
+    end_right_gravity = true,
+  })
+end
+
+local function get_extmark_pos(bufnr, id)
+  local row, col, details = unpack(api.nvim_buf_get_extmark_by_id(bufnr, ns, id, { details = true }))
+  return row, col, details and details.end_row or row, details and details.end_col or col
+end
+
+local function set_extmark_text(bufnr, id, text)
+  local row, col, end_row, end_col = get_extmark_pos(bufnr, id)
+  api.nvim_buf_set_text(bufnr, row, col, end_row, end_col, vim.split(text, "\n"))
+end
+
+local function cleanup(bufnr)
+  api.nvim_buf_clear_namespace(bufnr, ns, 0, -1)
+  local F = vim.F.if_nil(vim.on_key, vim.register_keystroke_callback)
+  F(nil, ns)
+end
+
+local function entrypoint(structure)
+  local bufnr = vim.api.nvim_get_current_buf()
+  local win = vim.api.nvim_get_current_win()
+
+  local evaluator = U.evaluate_snippet(structure)
+
+  -- Evalute the structure and insert placeholder markers for input variables
+  local S = evaluator.evaluate_structure({})
+
+  local placeholders = evaluator.evaluate_inputs({})
+  for i, v in ipairs(evaluator.inputs) do
+    S[v.first_index] = M.marker_with_placeholder_format:format(v.id, placeholders[i])
+  end
+
+  -- If the snippet contains a $0, insert a marker for the where the cursor will end up
+  if evaluator.zero_index then
+    S[evaluator.zero_index] = M.zero_pattern
+  end
+
+  local cursor_mark_id
+
+  -- Write the snippet to the buffer and create the extmarks
+  do
+    local lnum, col = unpack(api.nvim_win_get_cursor(win))
+
+    local current_line = api.nvim_get_current_line()
+    local prefix = current_line:sub(1, col)
+    local suffix = current_line:sub(col + 1)
+
+    local lines = vim.split(table.concat(S), "\n")
+    lines[1] = prefix .. lines[1]
+    lines[#lines] = lines[#lines] .. suffix
+    api.nvim_buf_set_lines(bufnr, lnum - 1, lnum, true, lines)
+
+    for i, v in ipairs(evaluator.structure) do
+      local s = S[i]
+      if U.is_variable(v) then
+        set_extmark(bufnr, i, lnum - 1, col, lnum - 1, col + #s)
+        if i == evaluator.zero_index then
+          cursor_mark_id = i
+        end
+      end
+
+      local tail = s:gsub("[^\n]*\n", function()
+        lnum = lnum + 1
+        col = 0
+        return ""
+      end)
+
+      col = col + #tail
+    end
+
+    if not cursor_mark_id then
+      cursor_mark_id = api.nvim_buf_set_extmark(bufnr, ns, lnum - 1, col, {})
+    end
+  end
+
+  local current_index = 0
+  local current_var
+  local resolved_inputs = {}
+
+  local R = { aborted = false, finished = false }
+
+  function R.advance(offset)
+    offset = offset or 1
+    current_index = math.max(math.min(current_index + offset, #evaluator.inputs + 1), 0)
+    if current_index == 0 then
+      R.aborted = true
+      cleanup(bufnr)
+      return true
+    end
+
+    -- User has moved past the last variable, so apply transformations and move the cursor to the
+    -- zero point
+    if current_index > #evaluator.inputs then
+      -- Move cursor to zero point
+      local cur_row, cur_col, cur_end_row, cur_end_col = get_extmark_pos(bufnr, cursor_mark_id)
+      api.nvim_buf_set_text(bufnr, cur_row, cur_col, cur_end_row, cur_end_col, {})
+      api.nvim_win_set_cursor(win, { cur_row + 1, cur_col })
+
+      R.finished = true
+      cleanup(bufnr)
+      return true
+    end
+
+    current_var = evaluator.inputs[current_index]
+
+    -- Clear highlights on all extmarks except those for current variable
+    for i, v in ipairs(evaluator.structure) do
+      if U.is_variable(v) then
+        local hl_group = v.order == current_index and M.hl_group or nil
+        local row, col, end_row, end_col = get_extmark_pos(bufnr, i)
+        set_extmark(bufnr, i, row, col, end_row, end_col, hl_group)
+      end
+    end
+
+    -- Set unresolved variables to their placeholder values
+    placeholders = evaluator.evaluate_inputs(resolved_inputs)
+    for i, v in ipairs(evaluator.structure) do
+      if U.is_variable(v) and v.is_input and (not resolved_inputs[v.id] or resolved_inputs[v.id] == "") then
+        local text = placeholders[v.id]
+        if v.id ~= current_var.id then
+          text = M.marker_with_placeholder_format:format(v.id, text)
+        end
+        set_extmark_text(bufnr, i, text)
+      end
+    end
+
+    -- Move the cursor to the current variable
+    local mark_row, mark_col, _, mark_end_col = get_extmark_pos(bufnr, current_var.first_index)
+    api.nvim_win_set_cursor(win, { mark_row + 1, mark_end_col })
+
+    -- Set resolved input to default value if one exists
+    resolved_inputs[current_var.id] = current_var.default
+
+    -- When a variable is highlighted, the first key pressed replaces the current value
+    -- with the user's input
+    local user_pressed_key = false
+
+    local F = vim.F.if_nil(vim.on_key, vim.register_keystroke_callback)
+    F(
+      vim.schedule_wrap(function(key)
+        if R.finished or R.aborted then
+          return
+        end
+
+        if not user_pressed_key and key:match("^[%w%p]$") then
+        print(key)
+          set_extmark_text(bufnr, current_var.first_index, key)
+          user_pressed_key = true
+          api.nvim_win_set_cursor(win, { mark_row + 1, mark_col + #key })
+          return
+        end
+
+        mark_row, mark_col, _, mark_end_col = get_extmark_pos(bufnr, current_var.first_index)
+        local line = api.nvim_buf_get_lines(bufnr, mark_row, mark_row + 1, true)[1]
+        local mark_text = line:sub(mark_col + 1, mark_end_col)
+
+        resolved_inputs[current_var.id] = mark_text
+        S = evaluator.evaluate_structure(resolved_inputs)
+
+        for i, v in ipairs(evaluator.structure) do
+          if U.is_variable(v) then
+            -- Update variables related to the current variable as well as
+            -- anonymous transforms
+            if v.order == current_index or v.transform and not v.id then
+              set_extmark_text(bufnr, i, S[i])
+            end
+          end
+        end
+      end),
+      ns
+    )
+  end
+
+  return R
+end
+
+return setmetatable(M, {
+  __call = function(_, ...)
+    return entrypoint(...)
+  end,
+})