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local m = require'lpeglabel'
local errUndef = 0
local errId = 1
local errComma = 2
local terror = {
[errUndef] = "Error",
[errId] = "Error: expecting an identifier",
[errComma] = "Error: expecting ','",
}
local g = m.P{
"S",
S = m.V"Id" * m.V"List",
List = -m.P(1) + ("," + m.T(errComma)) * m.V"Id" * m.V"List",
Id = m.R'az'^1 + m.T(errId),
}
function mymatch (g, s)
local r, e = g:match(s)
if not r then
return r, terror[e]
end
return r
end
print(mymatch(g, "a,b"))
print(mymatch(g, "a b"))
print(mymatch(g, ", b"))
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