merge sql placeholder ? and :x

sql_placeholder_merge.php

<?php
function quote_parse ($sql)
{
    $n = mb_strlen($sql);
    $state = 0;
    $word = '';
    $ret = [];
    $quote = '';
    for ($i=0; $i < $n; $i++) {
        $ch = mb_substr($sql, $i, 1);
        switch ($state) {
            case 0:
                if ($ch === '"' || $ch === "'") {
                    $quote = $ch;
                    if ($word !== '') {
                        $ret[]=$word;
                        $word = '';
                    }
                    $state = 1;
                } else {
                    $word .= $ch;
                }
                break;
            case 1:
                if ($ch === $quote) {
                    $quote = $ch;
                    $ret[]="$quote$word$quote";
                    $word = '';
                    $quote = '';
                    $state = 0;
                } else {
                    $word .= $ch;
                }
                break;
            default:
                # code...
                break;
        }

    }
    if ($word !== '') {
        $ret[] = $word;
    }
    return $ret;
}

function sql_placeholder_merge($sql, $bind = [])
{
    $list = quote_parse($sql);
    $ret_sql = '';
    foreach ($list as $key => $value) {
        if ($value && ($value[0] === '"' || $value[0] === "'")) {
            $ret_sql .= $value;
        } else {
            $ret_sql .= preg_replace_callback('/(\?|\:[a-zA-Z][a-zA-Z0-9_]*)/', function ($m) use(&$bind) {
                $val = $m[1];
                if ($val == '?') {
                    $val = quote (array_shift ($bind));
                } else if ($val[0] == ':') {
                    if (isset($bind[$val])) {
                        $val = $bind[$val];
                    } else {
                        $val = $bind[substr($val, 1)];
                    }
                    $val = quote($val);
                }
                return $val;
            }, $value);
        }
    }
    return $ret_sql;
}

sql_placeholder_merge_wrong.php

<?php
function sqlQuoteInto2 ($sql, $bind = null)
{
    if (isset ($bind)) {
        $sqlSplit = [];
        $sql = preg_replace_callback('/(\?|\:[a-zA-Z][a-zA-Z0-9_]*)/', function ($m) use(&$bind, &$sqlSplit) {
            $val = $m[1];
            if ($val == '?') {
                $val = quote (array_shift ($bind));
            } else if ($val[0] == ':') {
                if (isset($bind[$val])) {
                    $val = $bind[$val];
                } else {
                    $val = $bind[substr($val, 1)];
                }
                $val = quote($val);
            }
            return $val;
        }, $sql);
    }
    return $sql;
}