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local m = require'lpeglabel'
local re = require'relabel'
local terror = {
ErrId = "expecting an identifier",
ErrEnd = "expecting EOF",
fail = "undefined"
}
local id = m.R'az'^1
local g = m.P{
'S',
S = m.V'List' * (-m.P(1) + m.T'ErrEnd'),
List = m.V'Id' * (m.V'Comma' * (m.V'Id' + m.T'ErrId'))^0,
Id = m.V'Sp' * id,
Comma = m.V'Sp' * ',',
Sp = m.S' \n\t'^0,
}
function mymatch (g, s)
local r, e, pos = g:match(s)
if not r then
local line, col = re.calcline(s, pos)
local msg = "Error at line " .. line .. " (col " .. col .. "): "
return r, msg .. terror[e] .. " before '" .. s:sub(pos) .. "'"
end
return r
end
print(mymatch(g, "one,two"))
print(mymatch(g, "one two"))
print(mymatch(g, "one,\n two,\nthree,4"))
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