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