From 01a8b2a3d98f816b8b712a974f3d1e98f05152f5 Mon Sep 17 00:00:00 2001
From: sanine-a <sanine.not@pm.me>
Date: Fri, 14 Apr 2023 15:44:38 -0500
Subject: implement loading/saving entity db

---
 honey/ecs.lua | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

(limited to 'honey/ecs.lua')

diff --git a/honey/ecs.lua b/honey/ecs.lua
index 39f1c77..d544a37 100644
--- a/honey/ecs.lua
+++ b/honey/ecs.lua
@@ -1,5 +1,7 @@
 math.randomseed(os.time())
 
+local glm = require 'honey.glm'
+
 local module = {}
 setmetatable(module, {__index=_G})
 setfenv(1, module)
@@ -28,6 +30,71 @@ end
 setmetatable(EntityDb, {__call=EntityDb.new})
 
 
+local function serialize(tbl)
+	local tostr = function(x, value)
+		if type(x) == "table" then
+			if x.__tostring then
+				return tostring(x)
+			else
+				return serialize(x)
+			end
+		elseif type(x) == "string" then
+			if value then
+				return string.format("\"%s\"", x)
+			else
+				return x
+			end
+		else
+			return tostring(x)
+		end
+	end
+	local str = "{"
+	for key, value in pairs(tbl) do
+		if type(key) == "string" and string.match(key, "^_") then
+			-- ignore keys starting with an underscore
+		else
+			str = str .. string.format("%s=%s,", tostr(key), tostr(value, true))
+		end
+	end
+	str = string.sub(str, 1, -2) .. "}"
+	return str
+end
+
+
+-- save current database to file
+function EntityDb.save(self, filename)
+	local file, err = io.open(filename, "w")
+	if not file then error(err) end
+
+	for entity in pairs(self.entities) do
+		local components = self:queryEntity(entity)
+		file:write(string.format("Entity(\"%s\", %s)\n", entity, serialize(components)))
+	end
+
+	file:close()
+end
+
+
+-- load database from file
+function EntityDb.load(self, filename)
+	self.entities = {}
+	self.components = {}
+	local env = {
+		Entity = function(id, components)
+			print("add entity:", id)
+			self:createEntity(id)
+			self:addComponents(id, components)
+		end,
+		Vec3 = glm.Vec3,
+		Mat4 = glm.Mat4,
+	}
+	local f, err = loadfile(filename)
+	if not f then error(err) end
+	setfenv(f, env)
+	f()
+end
+
+
 -- check if a given entity id is legitimate
 function EntityDb.checkIsValid(self, id)
 	if not self.entities[id] then
-- 
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