How to replace many symbols with a single word in Lua? - lua

Question

I must replace all of these characters, "①②③④⑤⑥⑦⑧⑨⑩", with "\item".
I have used this code:
stra = string.gsub(text, "①", "\\item")
strb = string.gsub(stra, "②", "\\item")
strc = string.gsub(strb, "③", "\\item")
strd = string.gsub(strc, "④", "\\item")
stre = string.gsub(strd, "⑤", "\\item")
However, this is very verbose. Is there a simpler way to replace all of those items?

Answer 1

local symbols_trans = {
["\226\145\160"]--[[①]] = "\\item1",
["\226\145\161"]--[[②]] = "\\bananas",
["\226\145\162"]--[[③]] = "\\cactus",
["\226\145\163"]--[[④]] = "\\etc",
["\226\145\164"]--[[⑤]] = "\\item5",
["\226\145\165"]--[[⑥]] = "\\item6",
["\226\145\166"]--[[⑦]] = "\\item7",
["\226\145\167"]--[[⑧]] = "\\item8",
["\226\145\168"]--[[⑨]] = "\\item9",
["\226\145\169"]--[[⑩]] = "\\item10",
}
text = string.gsub(text, "(\266\145.)", symbol_trans)
Or if you want to replace them all with"\\item":
text = string.gsub(text,
"\266\145[\160-\169]",
"\\item"
)
[\160-\169] is equivalent to [\160\161\162\163\164\165\166\167\168\169].
See the Lua manual for information on ranges and, in general, Lua patterns.
You could also be fancy:
text = string.gsub(text,
"\266\145([\160-169])",
function(c)
return "\\item"..(string.byte(c)-160+1)
end
)
This will turn ① into \item1, ② into \item2, and so on.

Answer 2

Use a "set" as described in the tutorial: http://lua-users.org/wiki/PatternsTutorial
string.gsub(text, "[①②③④⑤⑥⑦⑧⑨⑩]", "\\item")

Answer 3

Is there a simpler way to replace all of those items?
Not without a Lua pattern matching library that knows what UTF-8 is. Lua is not Unicode aware; it has no idea how to search for Unicode symbols.
If you're using some non-multibyte encoding, then what John suggested might work. But not if it's UTF-8.
For your specific case, you could always do this:
local symbolsToChange { "①", "②", ...}
for i, sym in ipairs(symbolsToChange) do
string.gsub(text, sym, "\\item")
end