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Rework dumping functions
Changes:
  * Add comments to explain the dumping code
  * Add support for dumping values of any type (as '<' <type> '>')
  * Add support for tables as keys in dump2()
  * Make dump2() return it's result (like dump()) rather than printing it
  * Simplify and optimize function serialization via serialize()
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ShadowNinja committed May 24, 2014
1 parent 660e636 commit 882e12f
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Showing 2 changed files with 69 additions and 47 deletions.
114 changes: 68 additions & 46 deletions builtin/common/misc_helpers.lua
@@ -1,79 +1,101 @@
-- Minetest: builtin/misc_helpers.lua

--------------------------------------------------------------------------------
function basic_dump2(o)
if type(o) == "number" then
function basic_dump(o)
local tp = type(o)
if tp == "number" then
return tostring(o)
elseif type(o) == "string" then
elseif tp == "string" then
return string.format("%q", o)
elseif type(o) == "boolean" then
elseif tp == "boolean" then
return tostring(o)
elseif type(o) == "function" then
return "<function>"
elseif type(o) == "userdata" then
return "<userdata>"
elseif type(o) == "nil" then
elseif tp == "nil" then
return "nil"
-- Uncomment for full function dumping support.
-- Not currently enabled because bytecode isn't very human-readable and
-- dump's output is intended for humans.
--elseif tp == "function" then
-- return string.format("loadstring(%q)", string.dump(o))
else
error("cannot dump a " .. type(o))
return nil
return string.format("<%s>", tp)
end
end

--------------------------------------------------------------------------------
-- Dumps values in a line-per-value format.
-- For example, {test = {"Testing..."}} becomes:
-- _["test"] = {}
-- _["test"][1] = "Testing..."
-- This handles tables as keys and circular references properly.
-- It also handles multiple references well, writing the table only once.
-- The dumped argument is internal-only.

function dump2(o, name, dumped)
name = name or "_"
-- "dumped" is used to keep track of serialized tables to handle
-- multiple references and circular tables properly.
-- It only contains tables as keys. The value is the name that
-- the table has in the dump, eg:
-- {x = {"y"}} -> dumped[{"y"}] = '_["x"]'
dumped = dumped or {}
io.write(name, " = ")
if type(o) == "number" or type(o) == "string" or type(o) == "boolean"
or type(o) == "function" or type(o) == "nil"
or type(o) == "userdata" then
io.write(basic_dump2(o), "\n")
elseif type(o) == "table" then
if dumped[o] then
io.write(dumped[o], "\n")
else
dumped[o] = name
io.write("{}\n") -- new table
for k,v in pairs(o) do
local fieldname = string.format("%s[%s]", name, basic_dump2(k))
dump2(v, fieldname, dumped)
if type(o) ~= "table" then
return string.format("%s = %s\n", name, basic_dump(o))
end
if dumped[o] then
return string.format("%s = %s\n", name, dumped[o])
end
dumped[o] = name
-- This contains a list of strings to be concatenated later (because
-- Lua is slow at individual concatenation).
local t = {}
for k, v in pairs(o) do
local keyStr
if type(k) == "table" then
if dumped[k] then
keyStr = dumped[k]
else
-- Key tables don't have a name, so use one of
-- the form _G["table: 0xFFFFFFF"]
keyStr = string.format("_G[%q]", tostring(k))
-- Dump key table
table.insert(t, dump2(k, keyStr, dumped))
end
else
keyStr = basic_dump(k)
end
else
error("cannot dump a " .. type(o))
return nil
local vname = string.format("%s[%s]", name, keyStr)
table.insert(t, dump2(v, vname, dumped))
end
return string.format("%s = {}\n%s", name, table.concat(t))
end

--------------------------------------------------------------------------------
-- This dumps values in a one-line format, like serialize().
-- For example, {test = {"Testing..."}} becomes {["test"] = {[1] = "Testing..."}}
-- This supports tables as keys, but not circular references.
-- It performs poorly with multiple references as it writes out the full
-- table each time.
-- The dumped argument is internal-only.

function dump(o, dumped)
-- Same as "dumped" in dump2. The difference is that here it can only
-- contain boolean (and nil) values since multiple references aren't
-- handled properly.
dumped = dumped or {}
if type(o) == "number" then
return tostring(o)
elseif type(o) == "string" then
return string.format("%q", o)
elseif type(o) == "table" then
if type(o) == "table" then
if dumped[o] then
return "<circular reference>"
end
dumped[o] = true
local t = {}
for k,v in pairs(o) do
t[#t+1] = "[" .. dump(k, dumped) .. "] = " .. dump(v, dumped)
for k, v in pairs(o) do
k = dump(k, dumped)
v = dump(v, dumped)
table.insert(t, string.format("[%s] = %s", k, v))
end
return "{" .. table.concat(t, ", ") .. "}"
elseif type(o) == "boolean" then
return tostring(o)
elseif type(o) == "function" then
return "<function>"
elseif type(o) == "userdata" then
return "<userdata>"
elseif type(o) == "nil" then
return "nil"
return string.format("{%s}", table.concat(t, ", "))
else
error("cannot dump a " .. type(o))
return nil
return basic_dump(o)
end
end

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2 changes: 1 addition & 1 deletion builtin/common/serialize.lua
Expand Up @@ -113,7 +113,7 @@ function core.serialize(x)
elseif t=="string" then return string.format("%q", x)
elseif t=="boolean" then return x and "true" or "false"
elseif t=="function" then
return "loadstring("..string.format("%q", string.dump(x))..")"
return string.format("loadstring(%q)", string.dump(x))
elseif t=="table" then
local acc = { }
local idx_dumped = { }
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