95 lines
3.0 KiB
Lua
95 lines
3.0 KiB
Lua
--[[- The @{cc.expect} library provides helper functions for verifying that
|
|
function arguments are well-formed and of the correct type.
|
|
|
|
@module cc.expect
|
|
@usage Define a basic function and check it has the correct arguments.
|
|
|
|
local expect = require "cc.expect"
|
|
local expect, field = expect.expect, expect.field
|
|
|
|
local function add_person(name, info)
|
|
expect(1, name, "string")
|
|
expect(2, info, "table", "nil")
|
|
|
|
if info then
|
|
print("Got age=", field(info, "age", "number"))
|
|
print("Got gender=", field(info, "gender", "string", "nil"))
|
|
end
|
|
end
|
|
|
|
add_person("Anastazja") -- `info' is optional
|
|
add_person("Kion", { age = 23 }) -- `gender' is optional
|
|
add_person("Caoimhin", { age = 23, gender = true }) -- error!
|
|
]]
|
|
|
|
local native_select, native_type = select, type
|
|
|
|
local function get_type_names(...)
|
|
local types = table.pack(...)
|
|
for i = types.n, 1, -1 do
|
|
if types[i] == "nil" then table.remove(types, i) end
|
|
end
|
|
|
|
if #types <= 1 then
|
|
return tostring(...)
|
|
else
|
|
return table.concat(types, ", ", 1, #types - 1) .. " or " .. types[#types]
|
|
end
|
|
end
|
|
--- Expect an argument to have a specific type.
|
|
--
|
|
-- @tparam number index The 1-based argument index.
|
|
-- @param value The argument's value.
|
|
-- @tparam string ... The allowed types of the argument.
|
|
-- @return The given `value`.
|
|
-- @throws If the value is not one of the allowed types.
|
|
local function expect(index, value, ...)
|
|
local t = native_type(value)
|
|
for i = 1, native_select("#", ...) do
|
|
if t == native_select(i, ...) then return value end
|
|
end
|
|
|
|
-- If we can determine the function name with a high level of confidence, try to include it.
|
|
local name
|
|
if native_type(debug) == "table" and native_type(debug.getinfo) == "function" then
|
|
local ok, info = pcall(debug.getinfo, 3, "nS")
|
|
if ok and info.name and #info.name ~= "" and info.what ~= "C" then name = info.name end
|
|
end
|
|
|
|
local type_names = get_type_names(...)
|
|
if name then
|
|
error(("bad argument #%d to '%s' (expected %s, got %s)"):format(index, name, type_names, t), 3)
|
|
else
|
|
error(("bad argument #%d (expected %s, got %s)"):format(index, type_names, t), 3)
|
|
end
|
|
end
|
|
|
|
--- Expect an field to have a specific type.
|
|
--
|
|
-- @tparam table tbl The table to index.
|
|
-- @tparam string index The field name to check.
|
|
-- @tparam string ... The allowed types of the argument.
|
|
-- @return The contents of the given field.
|
|
-- @throws If the field is not one of the allowed types.
|
|
local function field(tbl, index, ...)
|
|
expect(1, tbl, "table")
|
|
expect(2, index, "string")
|
|
|
|
local value = tbl[index]
|
|
local t = native_type(value)
|
|
for i = 1, native_select("#", ...) do
|
|
if t == native_select(i, ...) then return value end
|
|
end
|
|
|
|
if value == nil then
|
|
error(("field '%s' missing from table"):format(index), 3)
|
|
else
|
|
error(("bad field '%s' (expected %s, got %s)"):format(index, get_type_names(...), t), 3)
|
|
end
|
|
end
|
|
|
|
return {
|
|
expect = expect,
|
|
field = field,
|
|
}
|