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local re = require 'relabelrec'
local errinfo = {
{"errUndef", "undefined"},
{"errId", "expecting an identifier"},
{"errComma", "expecting ','"},
}
local errmsgs = {}
local labels = {}
for i, err in ipairs(errinfo) do
errmsgs[i] = err[2]
labels[err[1]] = i
end
re.setlabels(labels)
local g = re.compile[[
S <- Id List
List <- !. / Comma Id List
Id <- Sp [a-z]+ / %{errId}
Comma <- Sp ',' / %{errComma}
Sp <- %s*
]]
local errors
function recorderror (subject, pos, label)
local line, col = re.calcline(subject, pos)
table.insert(errors, { line = line, col = col, msg = errmsgs[labels[label]] })
return true
end
function sync (p)
return '( !(' .. p .. ') .)*'
end
local grec = re.compile(
"S <- %g //{errComma} ErrComma //{errId} ErrId" .. "\n" ..
"ErrComma <- ('' -> 'errComma' => recorderror) " .. sync('!. / [a-z]+') .. "\n" ..
"ErrId <- ('' -> 'errId' => recorderror) (!(!. / ',') .)*"
, {g = g, recorderror = recorderror})
function mymatch (g, s)
errors = {}
local r, e, sfail = g:match(s)
if #errors > 0 then
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
return nil, table.concat(out, "\n")
end
return r
end
print(mymatch(grec, "one,two"))
print(mymatch(grec, "one two three"))
print(mymatch(grec, "1,\n two, \n3,"))
print(mymatch(grec, "one\n two123, \nthree,"))
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