fix(previewer): cache fzf port & fix "Too many opened files" issue (#604

)

lua/fzfx/commons/fileios.lua

@@ -136,6 +136,51 @@ M.FileLineReader = FileLineReader
 
 -- FileLineReader }
 
+-- CachedFileReader {
+
+--- @class commons.CachedFileReader
+--- @field filename string
+--- @field cache string?
+local CachedFileReader = {}
+
+--- @param filename string
+--- @return commons.CachedFileReader
+function CachedFileReader:open(filename)
+  local o = {
+    filename = filename,
+    cache = nil,
+  }
+  setmetatable(o, self)
+  self.__index = self
+  return o
+end
+
+--- @param opts {trim:boolean?}?
+--- @return string?
+function CachedFileReader:read(opts)
+  opts = opts or {}
+  opts.trim = type(opts.trim) == "boolean" and opts.trim or false
+
+  if self.cache == nil then
+    self.cache = M.readfile(self.filename)
+  end
+  if self.cache == nil then
+    return self.cache
+  end
+  return opts.trim and vim.trim(self.cache) or self.cache
+end
+
+--- @return string?
+function CachedFileReader:reset()
+  local saved = self.cache
+  self.cache = nil
+  return saved
+end
+
+M.CachedFileReader = CachedFileReader
+
+-- CachedFileReader }
+
 --- @param filename string
 --- @param opts {trim:boolean?}?
 --- @return string?
@@ -227,8 +272,8 @@ end
 --- @param filename string
 --- @return string[]|nil
 M.readlines = function(filename)
-  local reader = M.FileLineReader:open(filename) --[[@as commons.FileLineReader]]
-  if not reader then
+  local ok, reader = pcall(M.FileLineReader.open, M.FileLineReader, filename) --[[@as commons.FileLineReader]]
+  if not ok or reader == nil then
     return nil
   end
   local results = {}

lua/fzfx/commons/numbers.lua

@@ -123,15 +123,8 @@ end
 --- @return number
 M.random = function(m, n)
   local rand_result, rand_err = require("fzfx.commons.uv").random(4)
-  if rand_result == nil then
-    if m == nil and n == nil then
-      return math.random()
-    elseif m ~= nil and n == nil then
-      return math.random(m)
-    else
-      return math.random(m --[[@as integer]], n --[[@as integer]])
-    end
-  end
+  assert(rand_result ~= nil, rand_err)
+
   local bytes = {
     string.byte(rand_result --[[@as string]], 1, -1),
   }