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-- utility functions, in alpha order
local util = {}
-- Allow MyClass(ctor args...) equivalent to MyClass:new(ctor args...)
-- Usage:
-- local MyClass = {}
-- function MyClass:new(...)
-- ...
-- end
-- ...
-- util.classctor(MyClass)
-- or if your constructor is named something other than MyClass:new(), e.g.
-- MyClass:construct():
-- util.classctor(MyClass, MyClass.construct)
-- return MyClass
function util.classctor(class, ctor)
-- get the metatable for the passed class
local mt = getmetatable(class)
if mt == nil then
-- if it doesn't already have a metatable, then create one
mt = {}
setmetatable(class, mt)
end
-- now that class has a metatable, set its __call method to the specified
-- constructor method (class.new if not specified)
mt.__call = ctor or class.new
end
-- check if array-like table contains certain value
function util.contains(t, v)
return table.find(t, v) ~= nil
end
-- reliable count of the number of entries in table t
-- (since #t is unreliable)
function util.count(t)
local count = 0
for _ in pairs(t) do
count += 1
end
return count
end
-- cheap test whether table t is empty
function util.empty(t)
return not next(t)
end
-- recursive table equality
function util.equal(t1, t2)
if not (type(t1) == 'table' and type(t2) == 'table') then
return t1 == t2
end
-- both t1 and t2 are tables: get modifiable copy of t2
local temp = table.clone(t2)
for k, v in pairs(t1) do
-- if any key in t1 doesn't have same value in t2, not equal
if not util.equal(v, temp[k]) then
return false
end
-- temp[k] == t1[k], delete temp[k]
temp[k] = nil
end
-- All keys in t1 have equal values in t2; t2 == t1 if there are no extra keys in t2
return util.empty(temp)
end
return util
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