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--[[
Various helpful functions
]]
local util = {}
function util.cartesian(...)
-- cartesian(tbl1, tbl2, tbl3, ...)
-- for each table, returns a permutation of key, value in tbl1, tbl2, ect.
local args = {...}
return coroutine.wrap(function()
local cursors = {} -- cursors[1], cursors[3], ect. are the keys
for k,v in ipairs(args) do
local a,b = next(v,nil)
cursors[(k*2) - 1] = a
cursors[(k*2)] = b
end
coroutine.yield(unpack(cursors))
local any_left = true
while any_left do
while next(args[#args],cursors[#cursors - 1]) do
local a,b = next(args[#args],cursors[#cursors - 1])
cursors[#cursors - 1] = a
cursors[#cursors] = b
coroutine.yield(unpack(cursors))
end
any_left = false
for i = #args, 1, -1 do
if next(args[i],cursors[(i*2)-1]) then
cursors[(i*2)-1], cursors[i*2] = next(args[i],cursors[(i*2)-1])
for j = i+1, #args do
cursors[(j*2)-1], cursors[j*2] = next(args[j],nil)
end
coroutine.yield(unpack(cursors))
any_left = true
break
end
end
end
end)
end
-- Override tostring to display more info about the table
local old_tostring = tostring
local numtabs = 0
local printed_tables = {}
local function tostring_helper(el)
assert(type(el) == "table", "Tried to call helper with something that was not a table, it was a " .. type(el))
local mt = getmetatable(el)
if mt and mt.__tostring then
return mt.__tostring(el)
elseif printed_tables[el] == true then
return old_tostring(el)
else
printed_tables[el] = true
numtabs = numtabs + 1
local strbuilder = {"{"}
for k,v in pairs(el) do
local key,value
if type(k) == "table" then
key = tostring_helper(k)
else
key = old_tostring(k)
end
if type(v) == "table" then
value = tostring_helper(v)
else
value = old_tostring(v)
end
strbuilder[#strbuilder + 1] = string.format("%s%s : %s", string.rep("\t",numtabs), key, value)
end
strbuilder[#strbuilder + 1] = string.rep("\t",numtabs - 1) .. "}"
numtabs = numtabs - 1
return table.concat(strbuilder,"\n")
end
end
function tostring(el)
printed_tables = {}
if type(el) == "table" then
return tostring_helper(el)
end
return old_tostring(el)
end
function util.reverse(tbl, val)
val = val or true
local ret = {}
for _,v in ipairs(tbl) do
ret[v] = val
end
return ret
end
function util.typecheck(tbl, ...)
local args = {...}
assert(#args % 2 == 0,"Typecheck should have an odd number of arguments, found " .. tostring(#args + 1) .. ".")
for i = 1, #args, 2 do
assert(args[i] and type(args[i]) == "string", "Cannot check a field of type " .. type(args[i]) .. " at position " .. tostring(i + 1) .. ".")
assert(tbl[args[i]], "Failed to find a field: " .. args[i])
assert(args[i+1] and type(args[i + 1]) == "string", "Cannot check for a type " .. type(args[i + 1]) .. " at position " .. tostring(i + 2) .. ".")
assert(type(tbl[args[i]]) == args[i+1], "Expected a " .. args[i+1] .. " at position " .. tostring(i+2) .. " but found a " .. type(tbl[args[i]]))
end
return true
end
function util.peer_to_code(str)
-- Turn peerjs peer ids into shorter strings
-- Example: 0dbbe67a-5358-4ea2-910a-195754b556a7
-- = 16 bytes
local buffer = am.buffer(16)
local view = buffer:view("ubyte")
local i = 0
for byte in str:gmatch("%x%x") do
local n = tonumber(byte,16)
view[(i % 16) + 1] = n
i = i + 1
end
local encoded = am.base64_encode(buffer)
return encoded:gsub("[/+]",{["/"] = "-",["+"] = "_"}):sub(1,22) -- chop the last 2 glyphs, assume 16 bytes
end
function util.code_to_peer(str)
local padded = str:gsub("[_-]",{["-"] = "/", ["_"] = "+"}) .. "=="
local buffer = am.base64_decode(padded)
local view = buffer:view("ubyte")
local dashes = {4,2,2,2,6}
local builder = {}
local i = 1
while #dashes > 0 do
local nbytes = table.remove(dashes,1)
for _ = 1, nbytes do
table.insert(builder, string.format("%02x",view[i]))
i = i + 1
end
if #dashes > 0 then
table.insert(builder,"-")
end
end
ret = table.concat(builder)
return ret
end
return util
|
