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|
local F = {}
--- Returns the first argument which is not nil.
---
--- If all arguments are nil, returns nil.
---
--- Examples:
---
--- ```lua
--- local a = nil
--- local b = nil
--- local c = 42
--- local d = true
--- assert(vim.F.if_nil(a, b, c, d) == 42)
--- ```
---
---@generic T
---@param ... T
---@return T
function F.if_nil(...)
local nargs = select('#', ...)
for i = 1, nargs do
local v = select(i, ...)
if v ~= nil then
return v
end
end
return nil
end
-- Use in combination with pcall
function F.ok_or_nil(status, ...)
if not status then
return
end
return ...
end
-- Nil pcall.
function F.npcall(fn, ...)
return F.ok_or_nil(pcall(fn, ...))
end
--- Wrap a function to return nil if it fails, otherwise the value
function F.nil_wrap(fn)
return function(...)
return F.npcall(fn, ...)
end
end
--- like {...} except preserve the length explicitly
function F.pack_len(...)
return { n = select('#', ...), ... }
end
--- like unpack() but use the length set by F.pack_len if present
function F.unpack_len(t)
return unpack(t, 1, t.n)
end
return F
|
