raze-gles/polymer/eduke32/source/lunatic/savegame.lua

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-- Savegame facilities for Lunatic.
local string = require("string")
local table = require("table")
local format = string.format
local assert = assert
local getmetatable = getmetatable
local pairs = pairs
local setmetatable = setmetatable
local tostring = tostring
local type = type
local cansave_cdata = require("lprivate").cansave_cdata
module(...)
---=== Serialization, based on the idea from PiL ===---
assert(tostring(0/0)=="nan")
assert(tostring(1/0)=="inf")
-- Serialize a 'primitive' Lua value.
local function basicSerialize(o)
-- Compare with sb_get_initial_strbuf() below.
-- XXX: nil?
if (type(o) == "number") then
-- NOTE: NaN and infinity handled.
return tostring(o)
elseif (type(o) == "boolean") then
return o and "t" or "f"
elseif (type(o) == "string") then
-- TODO: return refname if it's shorter
return format("%q", o)
end
end
local function isSerializeable(obj)
return (getmetatable(obj)=="serializeable" or cansave_cdata(obj))
end
-- 'Save buffer' class. Objects of this class keep track of a string buffer
-- contiaining Lua code to recreate the values of particular variables from a
-- user Lunatic environment.
local savebuffer_mt = {
__index = {
-- Called on starting processing one module.
startmod = function(self, modname)
self:addrawf("if (N==%q) then", modname)
-- Will contain all tables and cdata refs of this module, indexed
-- by number.
self:addraw("local T={}")
self:resetRefs()
end,
-- Called on finishing processing one module.
endmod = function(self)
self:addraw("end")
end,
--== vvv INTERNAL vvv ===---
resetRefs = function(self)
self.numrefs = 0
self.val2ref = {}
self.havereq = {}
end,
-- Get the code necessary to create this object, usually 'require'ing a
-- module into a local variable.
getRequire = function(self, value)
local reqcode = value:_get_require()
if (self.havereq[reqcode] == nil) then
self.havereq[reqcode] = true
self.strbuf[#self.strbuf+1] = reqcode
end
end,
emitT = function(self, refcode, valcode, obj)
self:addrawf("%s=%s", refcode, valcode)
self.val2ref[obj] = refcode
end,
emitAssign = function(self, lhscode, refcode)
self:addrawf("%s=%s", lhscode, refcode)
end,
--== ^^^ INTERNAL ^^^ ===---
-- Add an entry of Lua object <value> that can be referenced by
-- <lhscode> on the left hand side of an assignment.
-- Returns 'true' if <value> cannot be serialized.
add = function(self, lhscode, value)
local valcode = basicSerialize(value)
if (valcode == nil) then
-- <value> is a not a 'basic' Lua object, but one passed by
-- reference.
if (not self.val2ref[value]) then
-- Object is being serialized for the first time.
-- Create a slot in 'T' for this object by which we can
-- refer to it in the following.
self.numrefs = self.numrefs+1
local refcode = format("T[%d]", self.numrefs)
if (isSerializeable(value)) then
-- We have a serializeable object from Lunatic
-- (e.g. actorvar).
self:getRequire(value)
self:emitT(refcode, value:_serialize(), value)
valcode = refcode
elseif (type(value)=="table") then
-- Create a new table for this gamevar.
-- TODO: emit table initializations where possible.
self:emitT(refcode, "{}", value)
for k,v in pairs(value) do
local keystr = basicSerialize(k)
if (keystr == nil) then
return true
end
-- Generate the name under which the table element
-- is referenced.
local refcode2 = format("%s[%s]", refcode, keystr)
-- Recurse!
if (self:add(refcode2, v)) then
return true
end
end
valcode = refcode
else
-- We have anything else: can't serialize.
return true
end
else
-- Object was previously serialized, get Lua expression it
-- can be referenced with.
valcode = self.val2ref[value]
end
end
self:emitAssign(lhscode, valcode)
end,
-- Add a single string to the buffer.
addraw = function(self, str)
self.strbuf[#self.strbuf+1] = str
end,
-- Add a single formatted string to the buffer.
addrawf = function(self, fmt, ...)
self:addraw(format(fmt, ...))
end,
-- Get the Lua code recreating the values as a string.
getcode = function(self)
self.strbuf[#self.strbuf+1] = "" -- add newline at EOS
return table.concat(self.strbuf, "\n")
end,
}
}
local function sb_get_initial_strbuf()
return {
"local nan, inf = 0/0, 1/0",
"local t, f = true, false",
}
end
-- Create a new savebuffer object.
function savebuffer()
-- .numrefs: how many table or cdata objects we have serialized
-- .val2ref: [<Lua object>] = <Lua code string>
-- .havereq = [<string>] = true
-- .strbuf: array of Lua code pieces
local sb = {
numrefs=0, val2ref={}, havereq={},
strbuf=sb_get_initial_strbuf()
}
return setmetatable(sb, savebuffer_mt)
end