perf(picker): dont use async when not needed

lua/snacks/picker/core/finder.lua

@@ -41,22 +41,27 @@ end
 
 ---@param picker snacks.Picker
 function M:run(picker)
+  local score = require("snacks.picker.core.matcher").DEFAULT_SCORE
   self.task:abort()
   self.items = {}
   local yield ---@type fun()
-  collectgarbage("stop") -- moar speed
   self.filter = picker.input.filter:clone({ trim = true })
   local finder = self._find(picker.opts, self.filter)
   local limit = picker.opts.limit or math.huge
+
+  -- PERF: if finder is a table, we can skip the async part
   if type(finder) == "table" then
     local items = finder --[[@as snacks.picker.finder.Item[] ]]
-    finder = function(cb)
-      for _, item in ipairs(items) do
-        cb(item)
-      end
+    for i, item in ipairs(items) do
+      item.idx, item.score = i, score
+      self.items[i] = item
     end
+    return
   end
+
+  collectgarbage("stop") -- moar speed
   ---@cast finder fun(cb:async fun(item:snacks.picker.finder.Item))
+  ---@diagnostic disable-next-line: await-in-sync
   self.task = Async.new(function()
     ---@async
     finder(function(item)
@@ -67,7 +72,7 @@ function M:run(picker)
         end
         return
       end
-      item.idx = #self.items + 1
+      item.idx, item.score = #self.items + 1, score
       self.items[item.idx] = item
       picker.matcher.task:resume()
       yield = yield or Async.yielder(YIELD_FIND)

lua/snacks/picker/core/matcher.lua

@@ -11,6 +11,8 @@ local Async = require("snacks.picker.util.async")
 ---@field live? boolean
 local M = {}
 M.__index = M
+M.DEFAULT_SCORE = 1000
+M.INVERSE_SCORE = 1000
 
 local YIELD_MATCH = 5 -- ms
 local clear = require("table.clear")
@@ -79,6 +81,14 @@ function M:run(picker, opts)
   if self.task:running() then
     return
   end
+
+  -- PERF: fast path for empty pattern
+  if self:empty() then
+    picker.list.items = picker.finder.items
+    picker:update()
+    return
+  end
+
   ---@async
   self.task = Async.new(function()
     local yield = Async.yielder(YIELD_MATCH)
@@ -230,7 +240,7 @@ end
 function M:match(item, opts)
   opts = opts or {}
   if self:empty() or (self.live and not opts.force) then
-    return 1000 -- empty pattern matches everything
+    return M.DEFAULT_SCORE -- empty pattern matches everything
   end
   local score = 0
   local positions = opts.positions and {} or nil ---@type number[]?
@@ -288,7 +298,7 @@ function M:_match(item, mods, positions)
   if mods.field then
     if item[mods.field] == nil then
       if mods.inverse then
-        return 1000
+        return M.INVERSE_SCORE
       end
       return
     end
@@ -323,7 +333,7 @@ function M:_match(item, mods, positions)
   end
   if mods.inverse then
     if not from then
-      return 1000
+      return M.INVERSE_SCORE
     end
     return
   end

lua/snacks/picker/core/picker.lua

@@ -349,6 +349,7 @@ function M:update()
   end
 
   local count = self.finder:count()
+  local list_count = self.list:count()
   -- Check if we should show the picker
   if not self.shown then
     -- Always show live pickers
@@ -376,7 +377,7 @@ function M:update()
         self:show()
         self:debug("show")
       end
-    elseif count > 1 or (count == 1 and not self.opts.auto_confirm) then -- show the picker if we have results
+    elseif list_count > 1 or (list_count == 1 and not self.opts.auto_confirm) then -- show the picker if we have results
       self:show()
       self:debug("show")
     end

lua/snacks/picker/util/async.lua

@@ -72,6 +72,10 @@ end
 ---@param event snacks.picker.AsyncEvent
 ---@param cb async fun(res:any, async:snacks.picker.Async)
 function Async:on(event, cb)
+  if event == "done" and not self:running() then
+    cb(nil, self)
+    return self
+  end
   self._on[event] = self._on[event] or {}
   table.insert(self._on[event], cb)
   return self