php - 如何将 HTML 字符引用 (ף) 转换为常规 UTF-8？

Question

我有一些希伯来文网站包含字符引用，例如:נוף

如果我将文件另存为 .html 并以 UTF-8 编码查看，我只能查看这些字母。

如果我尝试将其作为常规文本文件打开，则 UTF-8 编码不会显示正确的输出。

我注意到如果我打开一个文本编辑器并用 UTF-8 编写希伯来语，在这个例子中每个字符占用两个字节而不是 4 个字节行 (ו)

知道这是 UTF-16 还是任何其他类型的字母 UTF 表示形式吗？

如果可能，如何将其转换为普通字母？

使用最新的 PHP 版本。

Answer 1

那些是 character references通过以十进制 (&#<i>n</i>;) 或十六进制 (&#x<i>n</i>;) 表示法指定该字符的代码点来引用 ISO 10646 中的字符。

您可以使用 html_entity_decode 解码此类字符引用以及 entities defined for HTML 4 的实体引用，所以其他引用资料如 < , > , &也将被解码:

$str = html_entity_decode($str, ENT_NOQUOTES, 'UTF-8');

如果你只想解码数字字符引用，你可以使用这个:

function html_dereference($match) {
    if (strtolower($match[1][0]) === 'x') {
        $codepoint = intval(substr($match[1], 1), 16);
    } else {
        $codepoint = intval($match[1], 10);
    }
    return mb_convert_encoding(pack('N', $codepoint), 'UTF-8', 'UTF-32BE');
}
$str = preg_replace_callback('/&#(x[0-9a-f]+|[0-9]+);/i', 'html_dereference', $str);

---

作为YuriKolovsky和 thirtydot已在 another question 中指出，似乎浏览器供应商确实“默默地”就有关字符引用映射的某些内容达成了一致，这确实与规范不同并且没有记录。

似乎有一些字符引用通常会映射到 Latin 1 supplement但实际上映射到不同的字符上。这是由于映射宁愿从 Windows-1252 而不是 ISO 8859-1 映射字符，而 ISO 8859-1 是构建 Unicode 字符集的基础。 Jukka Korpela 写了一个extensive article on this topic .

现在这是对上述函数的扩展，可以处理这个问题:

function html_character_reference_decode($string, $encoding='UTF-8', $fixMappingBug=true) {
    $deref = function($match) use ($encoding, $fixMappingBug) {
        if (strtolower($match[1][0]) === "x") {
            $codepoint = intval(substr($match[1], 1), 16);
        } else {
            $codepoint = intval($match[1], 10);
        }
        // @see http://www.cs.tut.fi/~jkorpela/www/windows-chars.html
        if ($fixMappingBug && $codepoint >= 130 && $codepoint <= 159) {
            $mapping = array(
                8218, 402, 8222, 8230, 8224, 8225, 710, 8240, 352, 8249,
                338, 141, 142, 143, 144, 8216, 8217, 8220, 8221, 8226,
                8211, 8212, 732, 8482, 353, 8250, 339, 157, 158, 376);
            $codepoint = $mapping[$codepoint-130];
        }
        return mb_convert_encoding(pack("N", $codepoint), $encoding, "UTF-32BE");
    };
    return preg_replace_callback('/&#(x[0-9a-f]+|[0-9]+);/i', $deref, $string);
}

如果anonymous functions不可用(5.3.0 引入)，你也可以使用 create_function :

$deref = create_function('$match', '
    $encoding = '.var_export($encoding, true).';
    $fixMappingBug = '.var_export($fixMappingBug, true).';
    if (strtolower($match[1][0]) === "x") {
        $codepoint = intval(substr($match[1], 1), 16);
    } else {
        $codepoint = intval($match[1], 10);
    }
    // @see http://www.cs.tut.fi/~jkorpela/www/windows-chars.html
    if ($fixMappingBug && $codepoint >= 130 && $codepoint <= 159) {
        $mapping = array(
            8218, 402, 8222, 8230, 8224, 8225, 710, 8240, 352, 8249,
            338, 141, 142, 143, 144, 8216, 8217, 8220, 8221, 8226,
            8211, 8212, 732, 8482, 353, 8250, 339, 157, 158, 376);
        $codepoint = $mapping[$codepoint-130];
    }
    return mb_convert_encoding(pack("N", $codepoint), $encoding, "UTF-32BE");
');

---

这是另一个试图遵守 behavior of HTML 5 的函数:

function html5_decode($string, $flags=ENT_COMPAT, $charset='UTF-8') {
    $deref = function($match) use ($flags, $charset) {
        if ($match[1][0] === '#') {
            if (strtolower($match[1][0]) === '#') {
                $codepoint = intval(substr($match[1], 2), 16);
            } else {
                $codepoint = intval(substr($match[1], 1), 10);
            }

            // HTML 5 specific behavior
            // @see http://dev.w3.org/html5/spec/tokenization.html#tokenizing-character-references

            // handle Windows-1252 mismapping
            // @see http://www.cs.tut.fi/~jkorpela/www/windows-chars.html
            // @see http://dev.w3.org/html5/spec/tokenization.html#table-charref-overrides
            $overrides = array(
                0x00=>0xFFFD,0x80=>0x20AC,0x82=>0x201A,0x83=>0x0192,0x84=>0x201E,
                0x85=>0x2026,0x86=>0x2020,0x87=>0x2021,0x88=>0x02C6,0x89=>0x2030,
                0x8A=>0x0160,0x8B=>0x2039,0x8C=>0x0152,0x8E=>0x017D,0x91=>0x2018,
                0x92=>0x2019,0x93=>0x201C,0x94=>0x201D,0x95=>0x2022,0x96=>0x2013,
                0x97=>0x2014,0x98=>0x02DC,0x99=>0x2122,0x9A=>0x0161,0x9B=>0x203A,
                0x9C=>0x0153,0x9E=>0x017E,0x9F=>0x0178);
            if (isset($windows1252Mapping[$codepoint])) {
                $codepoint = $windows1252Mapping[$codepoint];
            }

            if (($codepoint >= 0xD800 && $codepoint <= 0xDFFF) || $codepoint > 0x10FFFF) {
                $codepoint = 0xFFFD;
            }
            if (($codepoint >= 0x0001 && $codepoint <= 0x0008) ||
                ($codepoint >= 0x000E && $codepoint <= 0x001F) ||
                ($codepoint >= 0x007F && $codepoint <= 0x009F) ||
                ($codepoint >= 0xFDD0 && $codepoint <= 0xFDEF) ||
                in_array($codepoint, array(
                    0x000B, 0xFFFE, 0xFFFF, 0x1FFFE, 0x1FFFF, 0x2FFFE, 0x2FFFF,
                    0x3FFFE, 0x3FFFF, 0x4FFFE, 0x4FFFF, 0x5FFFE, 0x5FFFF, 0x6FFFE,
                    0x6FFFF, 0x7FFFE, 0x7FFFF, 0x8FFFE, 0x8FFFF, 0x9FFFE, 0x9FFFF,
                    0xAFFFE, 0xAFFFF, 0xBFFFE, 0xBFFFF, 0xCFFFE, 0xCFFFF, 0xDFFFE,
                    0xDFFFF, 0xEFFFE, 0xEFFFF, 0xFFFFE, 0xFFFFF, 0x10FFFE, 0x10FFFF))) {
                $codepoint = 0xFFFD;
            }
            return mb_convert_encoding(pack("N", $codepoint), $charset, "UTF-32BE");
        } else {
            return html_entity_decode($match[0], $flags, $charset);
        }   
    };
    return preg_replace_callback('/&(#(?:x[0-9a-f]+|[0-9]+)|[A-Za-z0-9]+);/i', $deref, $string);
}

我还注意到在 PHP 5.4.0 中 html_entity_decode function为 HTML 5 行为添加了另一个名为 ENT_HTML5 的标志。