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local re = require 'relabel'
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) " .. sync('","') .. "-> default"
, {g = g, recorderror = recorderror, default = "NONE"})
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(grec, "one,two")
mymatch(grec, "one two three")
mymatch(grec, "1,\n two, \n3,")
mymatch(grec, "one\n two123, \nthree,")
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