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moved unique_mapping to ferris
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init.lua
1
init.lua
@ -33,7 +33,6 @@ local _batteries = {
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--
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timer = require_relative("timer"),
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pubsub = require_relative("pubsub"),
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unique_mapping = require_relative("unique_mapping"),
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state_machine = require_relative("state_machine"),
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async = require_relative("async"),
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manual_gc = require_relative("manual_gc"),
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@ -93,7 +93,6 @@ These modules are probably only useful to some folks in some circumstances, or a
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- [`colour`](./colour.lua) - Colour conversion routines. Alias `color`.
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- [`manual_gc`](./manual_gc.lua) - Get GC out of your update/draw calls. Useful when trying to get accurate profiling information; moves "randomness" of GC. Requires you to think a bit about your garbage budgets though.
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- [`measure`](./measure.lua) - Benchmarking helpers - measure the time or memory taken to run some code.
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- [`unique_mapping`](./unique_mapping.lua) - Generate a unique mapping from arbitrary lua values to numeric keys - essentially making up a consistent ordering for unordered data. Niche, but can be used to optimise draw batches for example, as you can't sort on textures without it.
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- [`make_pooled`](./make_pooled.lua) - add pooling/recycling capability to a class
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Any aliases are provided at both the `batteries` module level, and globally when exported.
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@ -1,62 +0,0 @@
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--[[
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unique mapping
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generate a mapping from unique values to plain numbers
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useful for arbitrarily ordering things that don't have
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a natural ordering in lua (eg textures for batching)
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]]
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local unique_mapping = {}
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unique_mapping._mt = {
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__index = unique_mapping,
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__mode = "kv", --weak refs
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}
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--(used as storage for non-weak data)
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local _MAP_VARS = setmetatable({}, {
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__mode = "k" --only keys are weak
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})
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--create a new unique mapping
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function unique_mapping:new()
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local r = setmetatable({}, self._mt)
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--set up the actual vars
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_MAP_VARS[r] = {
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current_index = 0,
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}
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return r
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end
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--private;
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--get the next index for this mapping
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function unique_mapping:_increment()
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local vars = _MAP_VARS[self]
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vars.current_index = vars.current_index + 1
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return vars.current_index
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end
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--get or build a mapping for a passed value
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function unique_mapping:map(value)
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local val = self[value]
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if val then
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return val
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end
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local i = self:_increment()
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self[value] = i
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return i
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end
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--get a function representing an a < b comparision that can be used
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--with table.sort and friends, like `table.sort(values, mapping:compare())`
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function unique_mapping:compare()
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-- memoised so it doesn't generate garbage, but also doesn't
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-- allocate until it's actually used
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if not self._compare then
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self._compare = function(a, b)
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return self:map(a) < self:map(b)
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end
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end
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return self._compare
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end
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return unique_mapping
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