add ecs.Filter

1 files changed, 100 insertions, 0 deletions

diff --git a/honey/ecs.lua b/honey/ecs.lua
new file mode 100644
index 0000000..ef682b5
--- /dev/null
+++ b/honey/ecs.lua
@@ -0,0 +1,100 @@
+local module = {}
+setmetatable(module, {__index=_G})
+setfenv(1, module)
+
+
+--===== filters =====--
+
+
+Filter = {}
+
+-- base filter creation
+function Filter.new(_, operation, tbl)
+	local self = {}
+	self.keys = {}
+	self.filters = {}
+	self.op = operation
+
+	for _, v in ipairs(tbl) do
+		if type(v) == "function" then
+			table.insert(self.filters, v)
+		elseif type(v) == "string" then
+			table.insert(self.keys, v)
+		end
+	end
+
+	return function(entity) 
+		return Filter.check(self, entity)
+	end
+end
+setmetatable(Filter, {__call=Filter.new})
+
+
+-- base filter checking
+function Filter.check(self, entity)
+	local funcname = "check" .. self.op
+	return Filter[funcname](self, entity)
+end
+
+
+-- AND filter (all keys and subfilters must match)
+function Filter.AND(tbl)
+	return Filter("AND", tbl)
+end
+function Filter.checkAND(self, entity)
+	for _, subfilter in ipairs(self.filters) do
+		if not subfilter(entity) then return false end
+	end
+	for _, key in ipairs(self.keys) do
+		if entity[key] == nil then return false end
+	end
+	return true
+end
+
+
+-- OR filter (at least one key or subfilter must match)
+function Filter.OR(tbl)
+	return Filter("OR", tbl)
+end
+function Filter.checkOR(self, entity)
+	for _, subfilter in ipairs(self.filters) do
+		if subfilter(entity) then return true end
+	end
+	for _, key in ipairs(self.keys) do
+		if entity[key] ~= nil then return true end
+	end
+	return false
+end
+
+
+-- NAND filter (at least one key or subfilter must NOT match)
+function Filter.NAND(tbl)
+	return Filter("NAND", tbl)
+end
+function Filter.checkNAND(self, entity)
+	for _, subfilter in ipairs(self.filters) do
+		if not subfilter(entity) then return true end
+	end
+	for _, key in ipairs(self.keys) do
+		if entity[key] == nil then return true end
+	end
+	return false
+end
+
+
+-- NOR filter (no keys or subfilters may match)
+function Filter.NOR(tbl)
+	return Filter("NOR", tbl)
+end
+function Filter.checkNOR(self, entity)
+	for _, subfilter in ipairs(self.filters) do
+		if subfilter(entity) then return false end
+	end
+	for _, key in ipairs(self.keys) do
+		if entity[key] ~= nil then return false end
+	end
+	return true
+end
+
+
+return module