How to use patterns to shorten only matching strings - lua

Question

I have a program that grabs a list of peripheral types, matches them to see if they're a valid type, and then executes type-specific code if they are valid.
However, some of the types can share parts of their name, with the only difference being their tier, I want to match these to the base type listed in a table of valid peripherals, but I can't figure out how to use a pattern to match them without the pattern returning nil for everything that doesn't match.
Here is the code to demonstrate my problem:
connectedPeripherals = {
[1] = "tile_thermalexpansion_cell_basic_name",
[2] = "modem",
[3] = "BigReactors-Turbine",
[4] = "tile_thermalexpansion_cell_resonant_name",
[5] = "monitor",
[6] = "tile_thermalexpansion_cell_hardened_name",
[7] = "tile_thermalexpansion_cell_reinforced_name",
[8] = "tile_blockcapacitorbank_name"
}
validPeripherals = {
["tile_thermalexpansion_cell"]=true,
["tile_blockcapacitorbank_name"]=true,
["monitor"]=true,
["BigReactors-Turbine"]=true,
["BigReactors-Reactor"]=true
}
for i = 1, #connectedPeripherals do
local periFunctions = {
["tile_thermalexpansion_cell"] = function()
--content
end,
["tile_blockcapacitorbank_name"] = function()
--content
end,
["monitor"] = function()
--content
end,
["BigReactors-Turbine"] = function()
--content
end,
["BigReactors-Reactor"] = function()
--content
end
}
if validPeripherals[connectedPeripherals[i]] then periFunctions[connectedPeripherals[i]]() end
end
If I try to run it like that, all of the thermalexpansioncells aren't recognized as valid peripherals, and if I add a pattern matching statement, it works for the thermalexpansioncells, but returns nil for everything else and causes an exception.
How do I do a match statement that only returns a shortened string for things that match and returns the original string for things that don't?
Is this possible?

Answer 1

If the short version doesn't contain any of the special characters from Lua patterns you can use the following:
long = "tile_thermalexpansion_cell_basic_name"
result = long:match("tile_thermalexpansion_cell") or long
print(result) -- prints the shorter version
result = long:match("foo") or long
print(result) -- prints the long version

Answer 2

Based on the comment, you can also use string.find to see the types match your peripheral names:
for i,v in ipairs(connectedPeripherals) do
local Valid = CheckValidity(v)
if Valid then Valid() end
end
where, CheckValidity will return the key from validPeripherals:
function CheckValidity( name )
for n, b in pairs(validPeripherals) do
if name:find( n ) then return n end
end
return false
end