local m = require'lpeglabel' local re = require'relabel' local terror = { ErrId = "expecting an identifier", ErrComma = "expecting ','", ErrList = "expecting a list of identifiers", fail = "undefined" } local subject, errors function recorderror(pos, lab) local line, col = re.calcline(subject, pos) table.insert(errors, { line = line, col = col, msg = terror[lab] }) end function record (lab) return (m.Cp() * m.Cc(lab)) / recorderror end function sync (p) return (-p * m.P(1))^0 end function defaultValue () return m.Cc"NONE" end local id = m.R'az'^1 local g = m.P{ "S", S = m.V"List" + (m.P(1) * m.T'ErrList'), List = m.V'Id' * (#m.P(1) * m.V'Comma' * (m.V'Id' + m.T'ErrId'))^0, Id = m.V'Sp' * m.C(id), Comma = m.V'Sp' * ',' + m.T'ErrComma', Sp = m.S' \n\t'^0, ErrId = record'ErrId' * sync(m.P",") * defaultValue(), ErrComma = record'ErrComma' * sync(id), ErrList = record'ErrList' * sync(m.P(-1)) * defaultValue() } function mymatch (g, s) errors = {} subject = s io.write("Input: ", s, "\n") local r = { g:match(s) } io.write("Captures (separated by ';'): ") for k, v in pairs(r) do io.write(v .. "; ") end io.write("\nSyntactic errors found: " .. #errors) if #errors > 0 then io.write("\n") local out = {} for i, err in ipairs(errors) do local msg = "Error at line " .. err.line .. " (col " .. err.col .. "): " .. err.msg table.insert(out, msg) end io.write(table.concat(out, "\n")) end print("\n") return r end mymatch(g, "one,two") mymatch(g, "one two three") mymatch(g, "1,\n two, \n3,") mymatch(g, "one\n two123, \nthree,")