Update neovim_luma_preview.lua

examples/neovim_luma_preview.lua

@@ -6,33 +6,93 @@
 
 local preview_buf = nil
 local preview_win = nil
+local active_job = nil
+local update_id = 0
 
-local function update_luma_preview()
-  local src_buf = vim.api.nvim_get_current_buf()
-  local lines = vim.api.nvim_buf_get_lines(src_buf, 0, -1, false)
-  local cmd = vim.env.LUMA_MARKDOWN_BIN or "luma_markdown"
-  local output = vim.fn.systemlist(cmd, lines)
+local function ensure_preview_buffer()
+  if preview_buf and vim.api.nvim_buf_is_valid(preview_buf) then return end
 
-  if not preview_buf or not vim.api.nvim_buf_is_valid(preview_buf) then
-    preview_buf = vim.api.nvim_create_buf(false, true)
-    vim.api.nvim_buf_set_option(preview_buf, "buftype", "nofile")
-    vim.api.nvim_buf_set_option(preview_buf, "bufhidden", "hide")
-    vim.api.nvim_buf_set_option(preview_buf, "swapfile", false)
-    vim.api.nvim_buf_set_option(preview_buf, "filetype", "markdown")
-  end
+  preview_buf = vim.api.nvim_create_buf(false, true)
+  vim.api.nvim_buf_set_option(preview_buf, "buftype", "nofile")
+  vim.api.nvim_buf_set_option(preview_buf, "bufhidden", "hide")
+  vim.api.nvim_buf_set_option(preview_buf, "swapfile", false)
+  vim.api.nvim_buf_set_option(preview_buf, "filetype", "markdown")
+end
 
+local function show_preview(src_buf, output)
+  ensure_preview_buffer()
   vim.api.nvim_buf_set_lines(preview_buf, 0, -1, false, output)
 
   if not preview_win or not vim.api.nvim_win_is_valid(preview_win) then
+    local src_win = vim.fn.bufwinid(src_buf)
+    if src_win == -1 then return end
+
+    vim.api.nvim_set_current_win(src_win)
     vim.cmd "rightbelow vsplit"
     preview_win = vim.api.nvim_get_current_win()
     vim.api.nvim_win_set_buf(preview_win, preview_buf)
 
-    local src_win = vim.fn.bufwinid(src_buf)
-    if src_win ~= -1 then vim.api.nvim_set_current_win(src_win) end
+    vim.api.nvim_set_current_win(src_win)
   end
 end
 
+local function update_luma_preview()
+  local src_buf = vim.api.nvim_get_current_buf()
+  local lines = vim.api.nvim_buf_get_lines(src_buf, 0, -1, false)
+  local changedtick = vim.api.nvim_buf_get_changedtick(src_buf)
+  local cmd = vim.env.LUMA_MARKDOWN_BIN or "luma_markdown"
+
+  update_id = update_id + 1
+  local this_update = update_id
+
+  if active_job then
+    vim.fn.jobstop(active_job)
+    active_job = nil
+  end
+
+  local output = {}
+  local errors = {}
+  local job
+  job = vim.fn.jobstart({ cmd }, {
+    stdin = "pipe",
+    stdout_buffered = true,
+    stderr_buffered = true,
+    on_stdout = function(_, data)
+      if data then vim.list_extend(output, data) end
+    end,
+    on_stderr = function(_, data)
+      if data then vim.list_extend(errors, data) end
+    end,
+    on_exit = function(_, exit_code)
+      if active_job == job then active_job = nil end
+      if this_update ~= update_id then return end
+      if not vim.api.nvim_buf_is_valid(src_buf) then return end
+      if vim.api.nvim_buf_get_changedtick(src_buf) ~= changedtick then return end
+
+      if exit_code ~= 0 then
+        local message = table.concat(errors, "\n")
+        if message ~= "" then
+          vim.notify("Luma preview failed: " .. message, vim.log.levels.ERROR)
+        end
+        return
+      end
+
+      -- io.println adds a final newline; systemlist used to remove it.
+      if output[#output] == "" then table.remove(output) end
+      show_preview(src_buf, output)
+    end,
+  })
+
+  if job <= 0 then
+    vim.notify("Could not start Luma preview: " .. cmd, vim.log.levels.ERROR)
+    return
+  end
+
+  active_job = job
+  vim.fn.chansend(job, table.concat(lines, "\n"))
+  vim.fn.chanclose(job, "stdin")
+end
+
 vim.api.nvim_create_autocmd("BufWritePost", {
   pattern = "*.luma",
   callback = update_luma_preview,