Re: Code Request: CSV parser written in Lua

[Roberto Ierusalimschy <roberto@...>]

Follows my code for this task (I had it already). CSV is not an easy task 
for Lua, mostly because of the '""' rule (a "" inside quotes is a single 
quote, but outside quotes this is simply the empty string). It would be 
much simpler if it used a conventional escape mechanism (such as '\"'). 

  function fromCSV (s)
    s = s..','          -- ending comma
    local t = {n=0}     -- table to collect fields
    local fieldstart = 1
    repeat
      if strfind(s, '^"', fieldstart) then    -- quoted field?
        local a, c
        local i  = fieldstart
        repeat
          a, i, c = strfind(s, '"("?)', i+1)  -- find closing quote
        until c ~= '"'    -- repeat if quote is followed by quote
        if not i then error('unmatched "') end
        tinsert(t, gsub(strsub(s, fieldstart+1, i-1), '""', '"'))
        fieldstart = strfind(s, ',', i) + 1
      else                -- unquoted; find next comma
        local nexti = strfind(s, ',', fieldstart)
        tinsert(t, strsub(s, fieldstart, nexti-1))
        fieldstart = nexti+1
      end
    until fieldstart > strlen(s)
    return t
  end


-- Roberto