80 lines
1.8 KiB
Lua
80 lines
1.8 KiB
Lua
--- Tables and metatables general utility algorithms.
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--
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-- @module gear.meta
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-- @copyright 2022 The DoubleFourteen Code Forge
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-- @author Lorenzo Cogotti
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local meta = {}
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--- Test whether 'obj' is an instance of the given class 'cls'.
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--
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-- Note that nil is the only instance of the nil class.
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--
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-- @tparam table obj object instance to be tested
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-- @tparam table cls class argument
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-- @treturn bool
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function meta.isinstance(obj, cls)
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if rawequal(cls, nil) then return rawequal(obj, nil) end
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repeat
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local m = getmetatable(obj)
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if rawequal(m, cls) then return true end
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obj = m
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until rawequal(obj, nil)
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return false
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end
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--- Merge table 'from' into table 'to'.
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--
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-- For every field in 'from', copy it to destination
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-- table 'to', whenever the same field is nil in that table.
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--
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-- The same process is applied recursively to sub-tables.
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--
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-- @tparam table to table to merge into
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-- @tparam table from table to merge from
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-- @treturn table destination table (a reference to 'to')
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function meta.mergetable(to, from)
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for k,v in pairs(from) do
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if to[k] == nil then
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to[k] = type(v) == 'table' and meta.mergetable({}, v) or v
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end
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end
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return to
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end
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--- Table deep copy.
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--
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-- Copy table 'obj', cloning any sub-table.
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-- Handles cyclic references.
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--
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-- @tparam table obj object to be copied
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-- @tparam[opt={}] table copied known copied sub-object table
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-- @treturn table newly created clone of 'obj'
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function meta.deepcopy(obj, copied)
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copied = copied or {}
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local r = {}
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copied[obj] = r
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for k,v in pairs(obj) do
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if type(v) == 'table' then
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local t = copied[v] or meta.deepcopy(v, copied)
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copied[v] = t -- NOP if object was already copied
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v = t
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end
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r[k] = v
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end
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return r
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end
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return meta
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