feat(picker): multi source picker. Combine multiple pickers (as opposed to just finders) in one picker

lua/snacks/picker/config/defaults.lua

@@ -15,6 +15,7 @@ local M = {}
 ---@field buf? boolean|number only show items for the current or given buffer
 ---@field paths? table<string, boolean> only show items that include or exclude the given paths
 ---@field filter? fun(item:snacks.picker.finder.Item, filter:snacks.picker.Filter):boolean? custom filter function
+---@field transform? fun(picker:snacks.Picker, filter:snacks.picker.Filter):boolean? filter transform. Return `true` to force refresh
 
 --- This is only used when using `opts.preview = "preview"`.
 --- It's a previewer that shows a preview based on the item data.
@@ -59,6 +60,7 @@ local M = {}
 ---@field preview? snacks.win.Config|{} preview window config
 
 ---@class snacks.picker.Config
+---@field multi? (string|snacks.picker.Config)[]
 ---@field source? string source name and config to use
 ---@field pattern? string|fun(picker:snacks.Picker):string pattern used to filter items by the matcher
 ---@field search? string|fun(picker:snacks.Picker):string search string used by finders

lua/snacks/picker/config/init.lua

@@ -76,7 +76,58 @@ function M.get(opts)
   end
 
   -- Merge the configs
-  return Snacks.config.merge(unpack(todo))
+  opts = Snacks.config.merge(unpack(todo))
+  M.multi(opts)
+  return opts
+end
+
+---@param opts snacks.picker.Config
+function M.multi(opts)
+  if not opts.multi then
+    return opts
+  end
+  local Finder = require("snacks.picker.core.finder")
+
+  local finders = {} ---@type snacks.picker.finder[]
+  local formats = {} ---@type snacks.picker.format[]
+  local previews = {} ---@type snacks.picker.preview[]
+  local confirms = {} ---@type snacks.picker.Action.spec[]
+
+  local sources = {} ---@type snacks.picker.Config[]
+  for _, source in ipairs(opts.multi) do
+    if type(source) == "string" then
+      source = { source = source }
+    end
+    ---@cast source snacks.picker.Config
+    source = Snacks.config.merge({}, opts.sources[source.source], source) --[[@as snacks.picker.Config]]
+    source.actions = source.actions or {}
+    if source.confirm then
+      source.actions.confirm = source.confirm
+    end
+    local finder = M.finder(source.finder)
+    finders[#finders + 1] = function(fopts, filter, picker)
+      fopts = Snacks.config.merge({}, vim.deepcopy(source), fopts)
+      return finder(fopts, filter, picker)
+    end
+    confirms[#confirms + 1] = source.actions.confirm or "jump"
+    previews[#previews + 1] = M.preview(source)
+    formats[#formats + 1] = M.format(source)
+    sources[#sources + 1] = source
+  end
+
+  opts.finder = opts.finder or Finder.multi(finders)
+  opts.format = opts.format or function(item, picker)
+    return formats[item.fid](item, picker)
+  end
+  opts.preview = opts.preview or function(ctx)
+    return previews[ctx.item.fid](ctx)
+  end
+  opts.confirm = opts.confirm
+    or function(picker, item, action)
+      return confirms[item.fid](picker, item, action)
+    end
+end
+
 ---@param opts snacks.picker.Config
 function M.format(opts)
   local ret = type(opts.format) == "string" and Snacks.picker.format[opts.format]
@@ -86,6 +137,15 @@ function M.format(opts)
   return ret
 end
 
+---@param opts snacks.picker.Config
+function M.transform(opts)
+  local ret = type(opts.transform) == "string" and require("snacks.picker.transform")[opts.transform]
+    or opts.transform
+    or nil
+  ---@cast ret snacks.picker.transform?
+  return ret
+end
+
 ---@param opts snacks.picker.Config
 function M.preview(opts)
   local preview = opts.preview or Snacks.picker.preview.file

lua/snacks/picker/init.lua

@@ -63,7 +63,7 @@ function M.pick(source, opts)
   opts = opts or {}
   opts.source = source or opts.source
   -- Show pickers if no source, items or finder is provided
-  if not (opts.source or opts.items or opts.finder) then
+  if not (opts.source or opts.items or opts.finder or opts.multi) then
     opts.source = "pickers"
     return M.pick(opts)
   end