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Spice up table equality checks

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Lars Mueller 2021-01-02 17:02:34 +01:00
parent 0eb59a85bf
commit 04a33ca841
1 changed files with 109 additions and 36 deletions
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145
table.lua
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@ -59,30 +59,34 @@ function is_circular(table)
return _is_circular(table) return _is_circular(table)
end end
function equals_noncircular(table_1, table_2) --+ Simple table equality check. Stack overflow if tables are too deep or circular.
local is_equal = table_1 == table_2 --+ Use `is_circular(table)` to check whether a table is circular.
if is_equal or type(table_1) ~= "table" or type(table_2) ~= "table" then --> Equality of noncircular tables if `table` and `other_table` are tables
--> `table == other_table` else
function equals_noncircular(table, other_table)
local is_equal = table == other_table
if is_equal or type(table) ~= "table" or type(other_table) ~= "table" then
return is_equal return is_equal
end end
if #table_1 ~= #table_2 then if #table ~= #other_table then
return false return false
end end
local table_keys = {} local table_keys = {}
for key_1, value_1 in pairs(table_1) do for key, value in pairs(table) do
local value_2 = table_2[key_1] local value_2 = other_table[key]
if not equals_noncircular(value_1, value_2) then if not equals_noncircular(value, value_2) then
if type(key_1) == "table" then if type(key) == "table" then
table_keys[key_1] = value_1 table_keys[key] = value
else else
return false return false
end end
end end
end end
for key_2, value_2 in pairs(table_2) do for other_key, other_value in pairs(other_table) do
if type(key_2) == "table" then if type(other_key) == "table" then
local found local found
for table, value in pairs(table_keys) do for table, value in pairs(table_keys) do
if equals_noncircular(key_2, table) and equals_noncircular(value_2, value) then if equals_noncircular(other_key, table) and equals_noncircular(other_value, value) then
table_keys[table] = nil table_keys[table] = nil
found = true found = true
break break
@ -92,7 +96,7 @@ function equals_noncircular(table_1, table_2)
return false return false
end end
else else
if table_1[key_2] == nil then if table[other_key] == nil then
return false return false
end end
end end
@ -100,45 +104,51 @@ function equals_noncircular(table_1, table_2)
return true return true
end end
-- circular references can be different as long as the content is identical equals = equals_noncircular
function equals_content(table_1, table_2)
--+ Table equality check properly handling circular tables - tables are equal as long as they provide equal key/value-pairs
--> Table content equality if `table` and `other_table` are tables
--> `table == other_table` else
function equals_content(table, other_table)
local equal_tables = {} local equal_tables = {}
local function _equals(table_1, table_2) local function _equals(table, other_equal_table)
local function set_equal_tables(value) local function set_equal_tables(value)
equal_tables[table_1] = equal_tables[table_1] or {} equal_tables[table] = equal_tables[table] or {}
equal_tables[table_1][table_2] = value equal_tables[table][other_equal_table] = value
return value return value
end end
local is_equal = table_1 == table_2 local is_equal = table == other_equal_table
if is_equal or type(table_1) ~= "table" or type(table_2) ~= "table" then if is_equal or type(table) ~= "table" or type(other_equal_table) ~= "table" then
return is_equal return is_equal
end end
if #table_1 ~= #table_2 then if #table ~= #other_equal_table then
return false return set_equal_tables(false)
end end
local lookup_equal = (equal_tables[table_1] or {})[table_2] local lookup_equal = (equal_tables[table] or {})[other_equal_table]
if lookup_equal ~= nil then if lookup_equal ~= nil then
return lookup_equal return lookup_equal
end end
-- Premise
set_equal_tables(true) set_equal_tables(true)
local table_keys = {} local table_keys = {}
for key_1, value_1 in pairs(table_1) do for key, value in pairs(table) do
local value_2 = table_2[key_1] local other_value = other_equal_table[key]
if not _equals(value_1, value_2) then if not _equals(value, other_value) then
if type(key_1) == "table" then if type(key) == "table" then
table_keys[key_1] = value_1 table_keys[key] = value
else else
return set_equal_tables(false) return set_equal_tables(false)
end end
end end
end end
for key_2, value_2 in pairs(table_2) do for other_key, other_value in pairs(other_equal_table) do
if type(key_2) == "table" then if type(other_key) == "table" then
local found local found = false
for table, value in pairs(table_keys) do for table_key, value in pairs(table_keys) do
if _equals(key_2, table) and _equals(value_2, value) then if _equals(table_key, other_key) and _equals(value, other_value) then
table_keys[table] = nil table_keys[table_key] = nil
found = true found = true
-- Breaking is fine as per transitivity
break break
end end
end end
@ -146,14 +156,77 @@ function equals_content(table_1, table_2)
return set_equal_tables(false) return set_equal_tables(false)
end end
else else
if table_1[key_2] == nil then if table[other_key] == nil then
return set_equal_tables(false) return set_equal_tables(false)
end end
end end
end end
return true return true
end end
return _equals(table_1, table_2) return _equals(table, other_table)
end
--+ Table equality check: content has to be equal, relations between tables as well
--+ The only difference may be in the memory addresses ("identities") of the (sub)tables
--+ Performance may suffer if the tables contain table keys
--+ equals(table, copy(table)) is true
--> equality (same tables after table reference substitution) of circular tables if `table` and `other_table` are tables
--> `table == other_table` else
function equals_references(table, other_table)
local function _equals(table, other_table, equal_refs)
if equal_refs[table] then
return equal_refs[table] == other_table
end
local is_equal = table == other_table
-- this check could be omitted if table key equality is being checked
if type(table) ~= "table" or type(other_table) ~= "table" then
return is_equal
end
if is_equal then
equal_refs[table] = other_table
return true
end
-- Premise: table = other table
equal_refs[table] = other_table
local table_keys = {}
for key, value in pairs(table) do
if type(key) == "table" then
table_keys[key] = value
else
local other_value = other_table[key]
if not _equals(value, other_value, equal_refs) then
return false
end
end
end
local other_table_keys = {}
for other_key, other_value in pairs(other_table) do
if type(other_key) == "table" then
other_table_keys[other_key] = other_value
elseif table[other_key] == nil then
return false
end
end
local function _next(current_key, equal_refs, available_keys)
local key, value = next(table_keys, current_key)
if key == nil then
return true
end
for other_key, other_value in pairs(other_table_keys) do
local copy_equal_refs = shallowcopy(equal_refs)
if _equals(key, other_key, copy_equal_refs) and _equals(value, other_value, copy_equal_refs) then
local copy_available_keys = shallowcopy(available_keys)
copy_available_keys[other_key] = nil
if _next(key, copy_equal_refs, copy_available_keys) then
return true
end
end
end
return false
end
return _next(nil, equal_refs, other_table_keys)
end
return _equals(table, other_table, {})
end end
function shallowcopy(table) function shallowcopy(table)