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Spice up table equality checks
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Lars Mueller
parent
0eb59a85bf
commit
04a33ca841
145
table.lua
145
table.lua
@ -59,30 +59,34 @@ function is_circular(table)
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return _is_circular(table)
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end
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function equals_noncircular(table_1, table_2)
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local is_equal = table_1 == table_2
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if is_equal or type(table_1) ~= "table" or type(table_2) ~= "table" then
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--+ Simple table equality check. Stack overflow if tables are too deep or circular.
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--+ Use `is_circular(table)` to check whether a table is circular.
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--> Equality of noncircular tables if `table` and `other_table` are tables
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--> `table == other_table` else
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function equals_noncircular(table, other_table)
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local is_equal = table == other_table
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if is_equal or type(table) ~= "table" or type(other_table) ~= "table" then
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return is_equal
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end
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if #table_1 ~= #table_2 then
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if #table ~= #other_table then
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return false
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end
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local table_keys = {}
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for key_1, value_1 in pairs(table_1) do
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local value_2 = table_2[key_1]
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if not equals_noncircular(value_1, value_2) then
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if type(key_1) == "table" then
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table_keys[key_1] = value_1
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for key, value in pairs(table) do
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local value_2 = other_table[key]
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if not equals_noncircular(value, value_2) then
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if type(key) == "table" then
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table_keys[key] = value
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else
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return false
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end
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end
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end
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for key_2, value_2 in pairs(table_2) do
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if type(key_2) == "table" then
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for other_key, other_value in pairs(other_table) do
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if type(other_key) == "table" then
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local found
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for table, value in pairs(table_keys) do
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if equals_noncircular(key_2, table) and equals_noncircular(value_2, value) then
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if equals_noncircular(other_key, table) and equals_noncircular(other_value, value) then
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table_keys[table] = nil
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found = true
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break
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@ -92,7 +96,7 @@ function equals_noncircular(table_1, table_2)
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return false
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end
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else
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if table_1[key_2] == nil then
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if table[other_key] == nil then
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return false
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end
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end
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@ -100,45 +104,51 @@ function equals_noncircular(table_1, table_2)
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return true
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end
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-- circular references can be different as long as the content is identical
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function equals_content(table_1, table_2)
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equals = equals_noncircular
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--+ Table equality check properly handling circular tables - tables are equal as long as they provide equal key/value-pairs
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--> Table content equality if `table` and `other_table` are tables
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--> `table == other_table` else
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function equals_content(table, other_table)
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local equal_tables = {}
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local function _equals(table_1, table_2)
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local function _equals(table, other_equal_table)
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local function set_equal_tables(value)
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equal_tables[table_1] = equal_tables[table_1] or {}
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equal_tables[table_1][table_2] = value
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equal_tables[table] = equal_tables[table] or {}
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equal_tables[table][other_equal_table] = value
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return value
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end
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local is_equal = table_1 == table_2
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if is_equal or type(table_1) ~= "table" or type(table_2) ~= "table" then
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local is_equal = table == other_equal_table
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if is_equal or type(table) ~= "table" or type(other_equal_table) ~= "table" then
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return is_equal
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end
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if #table_1 ~= #table_2 then
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return false
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if #table ~= #other_equal_table then
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return set_equal_tables(false)
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end
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local lookup_equal = (equal_tables[table_1] or {})[table_2]
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local lookup_equal = (equal_tables[table] or {})[other_equal_table]
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if lookup_equal ~= nil then
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return lookup_equal
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end
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-- Premise
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set_equal_tables(true)
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local table_keys = {}
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for key_1, value_1 in pairs(table_1) do
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local value_2 = table_2[key_1]
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if not _equals(value_1, value_2) then
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if type(key_1) == "table" then
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table_keys[key_1] = value_1
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for key, value in pairs(table) do
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local other_value = other_equal_table[key]
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if not _equals(value, other_value) then
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if type(key) == "table" then
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table_keys[key] = value
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else
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return set_equal_tables(false)
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end
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end
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end
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for key_2, value_2 in pairs(table_2) do
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if type(key_2) == "table" then
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local found
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for table, value in pairs(table_keys) do
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if _equals(key_2, table) and _equals(value_2, value) then
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table_keys[table] = nil
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for other_key, other_value in pairs(other_equal_table) do
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if type(other_key) == "table" then
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local found = false
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for table_key, value in pairs(table_keys) do
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if _equals(table_key, other_key) and _equals(value, other_value) then
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table_keys[table_key] = nil
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found = true
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-- Breaking is fine as per transitivity
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break
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end
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end
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@ -146,14 +156,77 @@ function equals_content(table_1, table_2)
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return set_equal_tables(false)
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end
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else
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if table_1[key_2] == nil then
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if table[other_key] == nil then
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return set_equal_tables(false)
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end
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end
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end
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return true
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end
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return _equals(table_1, table_2)
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return _equals(table, other_table)
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end
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--+ Table equality check: content has to be equal, relations between tables as well
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--+ The only difference may be in the memory addresses ("identities") of the (sub)tables
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--+ Performance may suffer if the tables contain table keys
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--+ equals(table, copy(table)) is true
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--> equality (same tables after table reference substitution) of circular tables if `table` and `other_table` are tables
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--> `table == other_table` else
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function equals_references(table, other_table)
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local function _equals(table, other_table, equal_refs)
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if equal_refs[table] then
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return equal_refs[table] == other_table
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end
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local is_equal = table == other_table
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-- this check could be omitted if table key equality is being checked
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if type(table) ~= "table" or type(other_table) ~= "table" then
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return is_equal
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end
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if is_equal then
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equal_refs[table] = other_table
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return true
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end
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-- Premise: table = other table
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equal_refs[table] = other_table
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local table_keys = {}
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for key, value in pairs(table) do
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if type(key) == "table" then
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table_keys[key] = value
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else
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local other_value = other_table[key]
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if not _equals(value, other_value, equal_refs) then
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return false
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end
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end
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end
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local other_table_keys = {}
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for other_key, other_value in pairs(other_table) do
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if type(other_key) == "table" then
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other_table_keys[other_key] = other_value
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elseif table[other_key] == nil then
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return false
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end
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end
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local function _next(current_key, equal_refs, available_keys)
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local key, value = next(table_keys, current_key)
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if key == nil then
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return true
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end
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for other_key, other_value in pairs(other_table_keys) do
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local copy_equal_refs = shallowcopy(equal_refs)
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if _equals(key, other_key, copy_equal_refs) and _equals(value, other_value, copy_equal_refs) then
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local copy_available_keys = shallowcopy(available_keys)
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copy_available_keys[other_key] = nil
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if _next(key, copy_equal_refs, copy_available_keys) then
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return true
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end
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end
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end
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return false
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end
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return _next(nil, equal_refs, other_table_keys)
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end
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return _equals(table, other_table, {})
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end
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function shallowcopy(table)
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