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39 lines
858 B
Lua
39 lines
858 B
Lua
--- Functions dealing with metatables and tables merging.
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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 a given class 'cls'.
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function meta.isinstance(obj, cls)
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repeat
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local m = getmetatable(obj)
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if m == cls then return true end
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obj = m
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until 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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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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return meta
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