Rather more robust nr_elements_in_seq
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@ -39,10 +39,10 @@ local LEAF_VALUE_TYPES = {
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['boolean'] = true,
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}
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local SHORT_STRING_MAX_LEN = 7
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local MINIMUM_NUMBER_OF_SET_ELEMENTS = 2
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local RECURSIVE_TOSTRING_TIMEOUT = 10
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local SHORT_STRING_MAX_LEN = 7 -- Range: [0, ∞[
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local MINIMUM_NUMBER_OF_SET_ELEMENTS = 2 -- Range: [1, ∞[
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local ALLOWED_HOLE_SIZE_IN_SEQUENCE = 1 -- Range: [0, ∞[. Set to 0, to completely disallow holes in sequences.
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local RECURSIVE_TOSTRING_TIMEOUT = 10 -- Range: [1, ∞[. High values may result in crashes on specially-crafted input.
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--------------------------------------------------------------------------------
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@ -98,6 +98,8 @@ local function largest_number_index (t)
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end
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local function nr_elements_in_table (t)
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-- Determines the total number of elements in the table.
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assert(type(t) == 'table')
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--
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local k, count = nil, -1
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@ -108,16 +110,30 @@ local function nr_elements_in_table (t)
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end
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local function nr_elements_in_seq (t)
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-- Determines the number of elements in the sequence part of the table.
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-- Allows holes of size `ALLOWED_HOLE_SIZE_IN_SEQUENCE`, before stopping.
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-- This function works even when the given table's metamethods throws errors.
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--
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-- Returns:
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-- * Number: number of elements
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-- * Boolean: whether the table has holes.
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assert(type(t) == 'table')
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if getmetatable(t) and getmetatable(t).__index then
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return 0, false -- FIXME: Temporary stopgap for when __index throws an
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-- error. I think we need to clone the numbers part of the table, to
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-- fix this.
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-- We don't want to crash if the __index metamethod throws an error, so we
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-- copy the pairs with number keys into a fresh table, which we then operate
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-- on lower down.
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if debug.getmetatable(t) and debug.getmetatable(t).__index then
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local t_prime = {}
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for k, v in pairs(t) do
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if type(k) == 'number' then t_prime[k] = v end
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end
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t = t_prime
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end
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-- Now we run though the table, from 1 and up.
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local i, last_elem_i, nr_elems, has_holes = 0, 0, 0, false
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while i <= last_elem_i + 2 do
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while i <= last_elem_i + 1 + ALLOWED_HOLE_SIZE_IN_SEQUENCE do
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i = i + 1
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if t[i] ~= nil then
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last_elem_i, nr_elems = i, nr_elems + 1
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@ -229,6 +229,13 @@ SUITE:addTest('Can count elements, even though metatable.__index throws errors',
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assert_equal(2, info[input].seq_elems)
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end)
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SUITE:addTest('Can count elements, even though metatable.__index throws errors and __metatable returns bogus', function ()
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local input = setmetatable({ 'hi', 'hello' }, {__index = function (_, k) error('Undefined access on key: '..k) end, __metatable = {}})
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local info = analyze_structure(input, math.huge)
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assert_equal(2, info[input].seq_elems)
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end)
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--------------------------------------------------------------------------------
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-- Uniform structure
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