feat(picker): persistent history. Closes #528

lua/snacks/picker/core/picker.lua

@@ -23,8 +23,7 @@ Async.BUDGET = 10
 ---@field start_time number
 ---@field title string
 ---@field closed? boolean
----@field hist_idx number
----@field hist_cursor number
+---@field history snacks.picker.History
 ---@field visual? snacks.picker.Visual
 local M = {}
 M.__index = M
@@ -46,8 +45,7 @@ M._active = {}
 ---@type snacks.picker.Last?
 M.last = nil
 
----@type {pattern: string, search: string, live?: boolean}[]
-M.history = {}
+---@alias snacks.picker.history.Record {pattern: string, search: string, live?: boolean}
 
 ---@hide
 ---@param opts? snacks.picker.Config
@@ -58,6 +56,16 @@ function M.new(opts)
     return M.resume()
   end
 
+  self.history = require("snacks.picker.util.history").new("picker", {
+    ---@param hist snacks.picker.history.Record
+    filter = function(hist)
+      if hist.pattern == "" and hist.search == "" then
+        return false
+      end
+      return true
+    end,
+  })
+
   local picker_count = vim.tbl_count(M._pickers)
   if picker_count > 0 then
     -- clear items from previous pickers for garbage collection
@@ -96,8 +104,6 @@ function M.new(opts)
   self.opts.win.input.actions = actions
   self.opts.win.list.actions = actions
   self.opts.win.preview.actions = actions
-  self.hist_idx = #M.history + 1
-  self.hist_cursor = self.hist_idx
 
   local sort = self.opts.sort or require("snacks.picker.sort").default()
   sort = type(sort) == "table" and require("snacks.picker.sort").default(sort) or sort
@@ -451,6 +457,7 @@ function M:close()
   if self.closed then
     return
   end
+  self:hist_record(true)
   self.closed = true
   M.last.selected = self:selected({ fallback = false })
   M.last.cursor = self.list.cursor
@@ -572,23 +579,31 @@ function M:find(opts)
 end
 
 --- Add current filter to history
+---@param force? boolean
 ---@private
-function M:hist_record()
-  M.history[self.hist_idx] = {
+function M:hist_record(force)
+  if not force and not self.history:is_current() then
+    return
+  end
+  self.history:record({
     pattern = self.input.filter.pattern,
     search = self.input.filter.search,
     live = self.opts.live,
-  }
+  })
 end
 
 --- Move the history cursor
 ---@param forward? boolean
 function M:hist(forward)
   self:hist_record()
-  self.hist_cursor = self.hist_cursor + (forward and 1 or -1)
-  self.hist_cursor = math.min(math.max(self.hist_cursor, 1), #M.history)
-  self.opts.live = M.history[self.hist_cursor].live
-  self.input:set(M.history[self.hist_cursor].pattern, M.history[self.hist_cursor].search)
+  if forward then
+    self.history:next()
+  else
+    self.history:prev()
+  end
+  local hist = self.history:get() --[[@as snacks.picker.history.Record]]
+  self.opts.live = hist.live
+  self.input:set(hist.pattern, hist.search)
 end
 
 --- Run the matcher with the current pattern.

lua/snacks/picker/util/history.lua

@@ -0,0 +1,73 @@
+---@class snacks.picker.History
+---@field path string
+---@field kv snacks.picker.KeyValue
+---@field idx number
+---@field cursor number
+local M = {}
+M.__index = M
+
+---@type table<string, snacks.picker.KeyValue>
+M.stores = {}
+
+-- Save the history on exit
+vim.api.nvim_create_autocmd("ExitPre", {
+  group = vim.api.nvim_create_augroup("snacks_history", { clear = true }),
+  callback = function()
+    for n, kv in pairs(M.stores) do
+      kv:close()
+      M.stores[n] = nil
+    end
+  end,
+})
+
+---@param name string
+---@param opts? {filter?: fun(value: string): boolean}
+function M.new(name, opts)
+  opts = opts or {}
+  local self = setmetatable({}, M)
+  self.path = vim.fn.stdpath("data") .. "/snacks/" .. name .. ".history"
+  if not M.stores[name] then
+    M.stores[name] = require("snacks.picker.util.kv").new(self.path, {
+      max_size = 1000,
+      ---@param a snacks.picker.KeyValue.entry
+      ---@param b snacks.picker.KeyValue.entry
+      cmp = function(a, b)
+        return a.key > b.key
+      end,
+    })
+  end
+  self.kv = M.stores[name]
+  -- re-index the data
+  self.kv.data = vim.tbl_values(self.kv.data)
+  if opts.filter then
+    self.kv.data = vim.tbl_filter(opts.filter, self.kv.data)
+  end
+  self.idx = #self.kv.data + 1
+  self.cursor = self.idx
+
+  return self
+end
+
+function M:is_current()
+  return self.cursor == self.idx
+end
+
+function M:record(value)
+  self.kv:set(self.idx, value)
+end
+
+function M:next()
+  self.cursor = math.min(self.cursor + 1, self.idx)
+  return self:get()
+end
+
+function M:prev()
+  self.cursor = math.max(self.cursor - 1, 1)
+  return self:get()
+end
+
+function M:get()
+  return self.kv:get(self.cursor)
+end
+
+return M

lua/snacks/picker/util/kv.lua

@@ -11,7 +11,7 @@ local uv = vim.uv or vim.loop
 ---@alias snacks.picker.KeyValue.entry {key:string, value:number}
 
 ---@param path string
----@param opts? {max_size?: number, cmp?: fun(a,b)}
+---@param opts? {max_size?: number, cmp?: fun(a:snacks.picker.KeyValue.entry, b:snacks.picker.KeyValue.entry): boolean}
 function M.new(path, opts)
   local self = setmetatable({}, M)
   self.data = {}
@@ -39,7 +39,7 @@ function M:set(key, value)
 end
 
 function M:get(key)
-  return self.data[key] or 0
+  return self.data[key]
 end
 
 function M:close()