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math.randomseed(os.time())
local module = {}
setmetatable(module, {__index=_G})
setfenv(1, module)
--===== EntityDb =====--
-- EntityDb is a database of entities and their associated components
-- it should be quite efficient to query for all entities with a given component, and reasonably
-- efficient to query for all components of a given entity
EntityDb = {}
EntityDb.__index = EntityDb
function EntityDb.new(_)
local self = {
entities = {},
components = {},
}
setmetatable(self, EntityDb)
return self
end
setmetatable(EntityDb, {__call=EntityDb.new})
-- check if a given entity id is legitimate
function EntityDb.checkIsValid(self, id)
if not self.entities[id] then
error(string.format("invalid entity id: %s", tostring(id)))
end
end
local random = math.random
local function uuid()
local template ='xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'
return string.gsub(template, '[xy]', function (c)
local v = (c == 'x') and random(0, 0xf) or random(8, 0xb)
return string.format('%x', v)
end)
end
-- create a new entity
function EntityDb.createEntity(self, id)
local id = id or uuid() -- allow inserting entities at preset ids for loading
self.entities[id] = true
return id
end
-- add a component to an entity
function EntityDb.addComponent(self, id, name, value)
self:checkIsValid(id)
-- create the relevant component table if it doesn't exist
if not self.components[name] then
self.components[name] = { count=0, data={} }
end
local component = self.components[name]
component.data[id] = value
component.count = component.count + 1
end
-- get all entities with a given component
function EntityDb.queryComponent(self, name)
return self.components[name].data
end
-- get all components associated with an entity
function EntityDb.queryEntity(self, id)
self:checkIsValid(id)
local query = {}
for name, component in pairs(self.components) do
query[name] = component.data[id]
end
return query
end
-- get a specific component from an entity
function EntityDb.getComponent(self, id, name)
self:checkIsValid(id)
return self.components[name].data[id]
end
-- remove a component from an entity
function EntityDb.removeComponent(self, id, name)
self:checkIsValid(id)
local component = self.components[name]
if component.data[id] ~= nil then
component.data[id] = nil
component.count = component.count - 1
if component.count == 0 then
self.components[name] = nil
end
end
end
-- remove an entity from the db
function EntityDb.deleteEntity(self, id)
self:checkIsValid(id)
for name in pairs(self.components) do
self:removeComponent(id, name)
end
self.entities[id] = nil
end
--===== SystemDb =====--
SystemDb = {}
SystemDb.__index = SystemDb
function SystemDb.new(_, entityDb)
local self = {
systems = {},
sorted = {},
entityDb = entityDb,
}
setmetatable(self, SystemDb)
return self
end
setmetatable(SystemDb, {__call=SystemDb.new})
local function systemId()
local template = "xx:xx:xx"
return string.gsub(template, "x", function(c)
return string.format("%x", random(0, 0xf))
end)
end
function SystemDb.addSystem(self, systemFunc, params)
local system
if type(systemFunc) == "table" then
system = systemFunc
else
local params = params or {}
params.db = self.entityDb
system = systemFunc(params)
end
local id = systemId()
self.systems[id] = system
table.insert(self.sorted, id)
self:sort()
return id
end
function SystemDb.sort(self)
table.sort(self.sorted, function(a, b) return (self.systems[a].priority or 100) < (self.systems[b].priority or 100) end)
end
function SystemDb.update(self, dt)
for _, system in ipairs(self.sorted) do
self.systems[system]:update(dt)
end
end
function SystemDb.removeSystem(self, id)
self.systems[id] = nil
for i=#self.sorted,1,-1 do
if self.sorted[i] == id then table.remove(self.sorted, i) end
end
end
--===== Database =====--
Database = {}
Database.__index = Database
function Database.new(_)
local self = {}
self.entityDb = EntityDb()
self.systemDb = SystemDb(self.entityDb)
setmetatable(self, Database)
return self
end
setmetatable(Database, {__call=Database.new})
function Database.isValidEntity(self, id)
return self.entityDb:checkIsValid(id)
end
function Database.createEntity(self, id)
return self.entityDb:createEntity(id)
end
function Database.addComponent(self, id, name, value)
return self.entityDb:addComponent(id, name, value)
end
function Database.queryComponent(self, name)
return self.entityDb:queryComponent(name)
end
function Database.queryEntity(self, id)
return self.entityDb:queryEntity(id)
end
function Database.getComponent(self, id, name)
return self.entityDb:getComponent(id, name)
end
function Database.removeComponent(self, id, name)
return self.entityDb:removeComponent(id, name)
end
function Database.deleteEntity(self, id)
return self.entityDb.deleteEntity(id)
end
function Database.addSystem(self, func, params)
return self.systemDb:addSystem(func, params)
end
function Database.update(self, dt)
return self.systemDb:update(dt)
end
function Database.removeSystem(self, id)
return self.systemDb:removeSystem(id)
end
return module
|
