csv_like_join.php

<?php

function csv_like_join($array, $quote_all = false)
{
    $result = '';
    $first = true;

    foreach ($array as $value) {
        if ($first) {
            $first = false;
        } else {
            $result .= ',';
        }

        if ($quote_all) {
            $result .= csv_quote($value);
        } else {
            $result .= maybe_csv_quote($value);
        }
    }

    return $result;
}

function csv_quote($string)
{
    return '"' . str_replace($string, '"', '""') . '"';
}

function maybe_csv_quote($string)
{
    if (need_csv_quote($string)) {
        return csv_quote($string);
    }

    return $string;
}

function need_csv_quote($string)
{
    if (
        strpos($string, ',') === false
        && strpos($string, '"') === false
        && strpos($string, "\r") === false
        && strpos($string, "\n") === false
    ) {
        return false;
    }

    return true;
}

function split_csv_line($record)
{
    $first = null;

    if (strlen($record) == 0) {
        return array('');
    }

    if ($record[0] === '"') {
        $first = '';
        $start = 1;

        while (
            $start < strlen($record)
            && ($end = strpos($record, '"', $start)) !== false
            && $end < strlen($record) - 1
            && $record[$end + 1] !== ','
        ) {
            if ($record[$end + 1] !== '"') {
                die("Found characters between double-quoted field and comma.");
            }

            $first .= substr($record, $start, $end - $start - 1);
            $start = $end + 2;
        }

        if ($start < strlen($record) || $end === false) {
            die("Could not find end-quote for double-quoted field");
        }

        $first .= substr($record, $start, $end - $start - 1);

        if ($end >= strlen($record) - 1) {
            return array($first);
        }

        /* Assertion: $record[$end + 1] == ',' */
        $rest = substr($record, $end + 2);
    } else {
        $end = strpos($record, ',');

        if ($end === false) {
            return array($record);
        }

        /* Assertion: $end < strlen($record) */

        $first = substr($record, 0, $end);
        $rest = substr($record, $end + 1);
    }

    $fields = split_csv_line($rest);
    array_unshift($fields, $first);
    return $fields;
}