dump_table: Sort keys before printing
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committed by
George Kiagiadakis

parent
86bfdbea13
commit
92d99f4a75
@@ -77,7 +77,56 @@ local function dump_table(t, indent)
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indent_str = indent_str .. "\t"
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end
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local kvpairs = {}
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for k, v in pairs(t) do
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table.insert(kvpairs, { k, v })
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end
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table.sort(kvpairs, function (lhs, rhs)
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local left_key, right_key = lhs[1], rhs[1]
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-- If the types are different, we sort by the type
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-- in alphabetical order. This means that numbers
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-- come before before strings, etc
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if type(left_key) ~= type(right_key) then
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return type(left_key) < type(right_key)
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end
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local key_type = type(left_key)
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-- Only numbers and strings have a well-defined order
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-- that's guaranteed to fulfill the requirements of
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-- table.sort (strict weak order)
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if key_type == "number" or key_type == "string" then
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return left_key < right_key
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end
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-- At this point, we have no good way to order the objects.
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-- We can't just do `left_key < right_key`, because this may fail
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-- if there's no `__lt` metamethod, and even if there is one,
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-- it might not be a strict weak order. (The Lua reference does
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-- not say what happens if the order is not strict weak, so it's
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-- undefined behaviour)
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-- That said, it's always mathematically "permitted" to return `false`,
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-- in which case, since both x < y and y < x are false, the elements
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-- are considered "equivalent" and may appear in any order in relation
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-- to each other. The elements are still sorted in relation to the
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-- *other* keys.
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return false
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-- To be a strict weak order, if x and y are equivalent, and y and z
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-- are equivalent, then x and z must be equivalent too. Otherwise the
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-- ordering is only a strict *partial* order.
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-- Note that the Lua 5.3 reference states that the order merely has to
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-- be a strict *partial* order, but since all weak orders are partial
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-- orders, this is not a problem.
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end)
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for _, pair in ipairs(kvpairs) do
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local k, v = table.unpack(pair)
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if (type(v) == "table") then
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print (indent_str .. tostring(k) .. ": ")
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dump_table(v, indent + 1)
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