moved unique_mapping to ferris

This commit is contained in:
Max Cahill 2022-12-05 18:10:21 +11:00
parent 844c9e8c8f
commit 0d88061e3b
3 changed files with 0 additions and 64 deletions

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@ -33,7 +33,6 @@ local _batteries = {
--
timer = require_relative("timer"),
pubsub = require_relative("pubsub"),
unique_mapping = require_relative("unique_mapping"),
state_machine = require_relative("state_machine"),
async = require_relative("async"),
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
- [`colour`](./colour.lua) - Colour conversion routines. Alias `color`.
- [`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.
- [`measure`](./measure.lua) - Benchmarking helpers - measure the time or memory taken to run some code.
- [`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.
- [`make_pooled`](./make_pooled.lua) - add pooling/recycling capability to a class
Any aliases are provided at both the `batteries` module level, and globally when exported.

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@ -1,62 +0,0 @@
--[[
unique mapping
generate a mapping from unique values to plain numbers
useful for arbitrarily ordering things that don't have
a natural ordering in lua (eg textures for batching)
]]
local unique_mapping = {}
unique_mapping._mt = {
__index = unique_mapping,
__mode = "kv", --weak refs
}
--(used as storage for non-weak data)
local _MAP_VARS = setmetatable({}, {
__mode = "k" --only keys are weak
})
--create a new unique mapping
function unique_mapping:new()
local r = setmetatable({}, self._mt)
--set up the actual vars
_MAP_VARS[r] = {
current_index = 0,
}
return r
end
--private;
--get the next index for this mapping
function unique_mapping:_increment()
local vars = _MAP_VARS[self]
vars.current_index = vars.current_index + 1
return vars.current_index
end
--get or build a mapping for a passed value
function unique_mapping:map(value)
local val = self[value]
if val then
return val
end
local i = self:_increment()
self[value] = i
return i
end
--get a function representing an a < b comparision that can be used
--with table.sort and friends, like `table.sort(values, mapping:compare())`
function unique_mapping:compare()
-- memoised so it doesn't generate garbage, but also doesn't
-- allocate until it's actually used
if not self._compare then
self._compare = function(a, b)
return self:map(a) < self:map(b)
end
end
return self._compare
end
return unique_mapping