47 lines
1.6 KiB
Lua
47 lines
1.6 KiB
Lua
--- The @{craftos.expect} library provides helper functions for verifying that
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-- function arguments are well-formed and of the correct type.
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--
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-- @module craftos.expect
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local native_select, native_type = select, type
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--- Expect an argument to have a specific type.
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--
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-- @tparam int index The 1-based argument index.
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-- @param value The argument's value.
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-- @tparam string ... The allowed types of the argument.
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-- @throws If the value is not one of the allowed types.
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local function expect(index, value, ...)
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local t = native_type(value)
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for i = 1, native_select("#", ...) do
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if t == native_select(i, ...) then return true end
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end
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local types = table.pack(...)
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for i = types.n, 1, -1 do
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if types[i] == "nil" then table.remove(types, i) end
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end
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local type_names
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if #types <= 1 then
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type_names = tostring(...)
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else
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type_names = table.concat(types, ", ", 1, #types - 1) .. " or " .. types[#types]
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end
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-- If we can determine the function name with a high level of confidence, try to include it.
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local name
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if native_type(debug) == "table" and native_type(debug.getinfo) == "function" then
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local ok, info = pcall(debug.getinfo, 3, "nS")
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if ok and info.name and #info.name ~= "" and info.what ~= "C" then name = info.name end
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end
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if name then
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error( ("bad argument #%d to '%s' (expected %s, got %s)"):format(index, name, type_names, t), 3 )
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else
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error( ("bad argument #%d (expected %s, got %s)"):format(index, type_names, t), 3 )
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end
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end
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return { expect = expect }
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