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<?php
declare(strict_types=1);
/*
* This file is part of the league/commonmark package.
*
* (c) Colin O'Dell <colinodell@gmail.com>
*
* Original code based on the CommonMark JS reference parser (https://bitly.com/commonmark-js)
* - (c) John MacFarlane
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace League\CommonMark\Util;
use League\CommonMark\Exception\InvalidArgumentException;
use League\CommonMark\Extension\CommonMark\Node\Block\HtmlBlock;
/**
* Provides regular expressions and utilities for parsing Markdown
*
* All of the PARTIAL_ regex constants assume that they'll be used in case-insensitive searches
* All other complete regexes provided by this class (either via constants or methods) will have case-insensitivity enabled.
*
* @phpcs:disable Generic.Strings.UnnecessaryStringConcat.Found
*
* @psalm-immutable
*/
final class RegexHelper
{
// Partial regular expressions (wrap with `/` on each side and add the case-insensitive `i` flag before use)
public const PARTIAL_ENTITY = '&(?:#x[a-f0-9]{1,6}|#[0-9]{1,7}|[a-z][a-z0-9]{1,31});';
public const PARTIAL_ESCAPABLE = '[!"#$%&\'()*+,.\/:;<=>?@[\\\\\]^_`{|}~-]';
public const PARTIAL_ESCAPED_CHAR = '\\\\' . self::PARTIAL_ESCAPABLE;
public const PARTIAL_IN_DOUBLE_QUOTES = '"(' . self::PARTIAL_ESCAPED_CHAR . '|[^"\x00])*"';
public const PARTIAL_IN_SINGLE_QUOTES = '\'(' . self::PARTIAL_ESCAPED_CHAR . '|[^\'\x00])*\'';
public const PARTIAL_IN_PARENS = '\\((' . self::PARTIAL_ESCAPED_CHAR . '|[^)\x00])*\\)';
public const PARTIAL_REG_CHAR = '[^\\\\()\x00-\x20]';
public const PARTIAL_IN_PARENS_NOSP = '\((' . self::PARTIAL_REG_CHAR . '|' . self::PARTIAL_ESCAPED_CHAR . '|\\\\)*\)';
public const PARTIAL_TAGNAME = '[a-z][a-z0-9-]*';
public const PARTIAL_BLOCKTAGNAME = '(?:address|article|aside|base|basefont|blockquote|body|caption|center|col|colgroup|dd|details|dialog|dir|div|dl|dt|fieldset|figcaption|figure|footer|form|frame|frameset|h1|head|header|hr|html|iframe|legend|li|link|main|menu|menuitem|nav|noframes|ol|optgroup|option|p|param|section|source|summary|table|tbody|td|tfoot|th|thead|title|tr|track|ul)';
public const PARTIAL_ATTRIBUTENAME = '[a-z_:][a-z0-9:._-]*';
public const PARTIAL_UNQUOTEDVALUE = '[^"\'=<>`\x00-\x20]+';
public const PARTIAL_SINGLEQUOTEDVALUE = '\'[^\']*\'';
public const PARTIAL_DOUBLEQUOTEDVALUE = '"[^"]*"';
public const PARTIAL_ATTRIBUTEVALUE = '(?:' . self::PARTIAL_UNQUOTEDVALUE . '|' . self::PARTIAL_SINGLEQUOTEDVALUE . '|' . self::PARTIAL_DOUBLEQUOTEDVALUE . ')';
public const PARTIAL_ATTRIBUTEVALUESPEC = '(?:' . '\s*=' . '\s*' . self::PARTIAL_ATTRIBUTEVALUE . ')';
public const PARTIAL_ATTRIBUTE = '(?:' . '\s+' . self::PARTIAL_ATTRIBUTENAME . self::PARTIAL_ATTRIBUTEVALUESPEC . '?)';
public const PARTIAL_OPENTAG = '<' . self::PARTIAL_TAGNAME . self::PARTIAL_ATTRIBUTE . '*' . '\s*\/?>';
public const PARTIAL_CLOSETAG = '<\/' . self::PARTIAL_TAGNAME . '\s*[>]';
public const PARTIAL_OPENBLOCKTAG = '<' . self::PARTIAL_BLOCKTAGNAME . self::PARTIAL_ATTRIBUTE . '*' . '\s*\/?>';
public const PARTIAL_CLOSEBLOCKTAG = '<\/' . self::PARTIAL_BLOCKTAGNAME . '\s*[>]';
public const PARTIAL_HTMLCOMMENT = '<!---->|<!--(?:-?[^>-])(?:-?[^-])*-->';
public const PARTIAL_PROCESSINGINSTRUCTION = '[<][?][\s\S]*?[?][>]';
public const PARTIAL_DECLARATION = '<![A-Z]+' . '[^>]*>';
public const PARTIAL_CDATA = '<!\[CDATA\[[\s\S]*?]\]>';
public const PARTIAL_HTMLTAG = '(?:' . self::PARTIAL_OPENTAG . '|' . self::PARTIAL_CLOSETAG . '|' . self::PARTIAL_HTMLCOMMENT . '|' .
self::PARTIAL_PROCESSINGINSTRUCTION . '|' . self::PARTIAL_DECLARATION . '|' . self::PARTIAL_CDATA . ')';
public const PARTIAL_HTMLBLOCKOPEN = '<(?:' . self::PARTIAL_BLOCKTAGNAME . '(?:[\s\/>]|$)' . '|' .
'\/' . self::PARTIAL_BLOCKTAGNAME . '(?:[\s>]|$)' . '|' . '[?!])';
public const PARTIAL_LINK_TITLE = '^(?:"(' . self::PARTIAL_ESCAPED_CHAR . '|[^"\x00])*"' .
'|' . '\'(' . self::PARTIAL_ESCAPED_CHAR . '|[^\'\x00])*\'' .
'|' . '\((' . self::PARTIAL_ESCAPED_CHAR . '|[^()\x00])*\))';
public const REGEX_PUNCTUATION = '/^[\x{2000}-\x{206F}\x{2E00}-\x{2E7F}\p{Pc}\p{Pd}\p{Pe}\p{Pf}\p{Pi}\p{Po}\p{Ps}\\\\\'!"#\$%&\(\)\*\+,\-\.\\/:;<=>\?@\[\]\^_`\{\|\}~]/u';
public const REGEX_UNSAFE_PROTOCOL = '/^javascript:|vbscript:|file:|data:/i';
public const REGEX_SAFE_DATA_PROTOCOL = '/^data:image\/(?:png|gif|jpeg|webp)/i';
public const REGEX_NON_SPACE = '/[^ \t\f\v\r\n]/';
public const REGEX_WHITESPACE_CHAR = '/^[ \t\n\x0b\x0c\x0d]/';
public const REGEX_UNICODE_WHITESPACE_CHAR = '/^\pZ|\s/u';
public const REGEX_THEMATIC_BREAK = '/^(?:\*[ \t]*){3,}$|^(?:_[ \t]*){3,}$|^(?:-[ \t]*){3,}$/';
public const REGEX_LINK_DESTINATION_BRACES = '/^(?:<(?:[^<>\\n\\\\\\x00]|\\\\.)*>)/';
/**
* @psalm-pure
*/
public static function isEscapable(string $character): bool
{
return \preg_match('/' . self::PARTIAL_ESCAPABLE . '/', $character) === 1;
}
/**
* @psalm-pure
*/
public static function isLetter(?string $character): bool
{
if ($character === null) {
return false;
}
return \preg_match('/[\pL]/u', $character) === 1;
}
/**
* Attempt to match a regex in string s at offset offset
*
* @psalm-param non-empty-string $regex
*
* @return int|null Index of match, or null
*
* @psalm-pure
*/
public static function matchAt(string $regex, string $string, int $offset = 0): ?int
{
$matches = [];
$string = \mb_substr($string, $offset, null, 'UTF-8');
if (! \preg_match($regex, $string, $matches, \PREG_OFFSET_CAPTURE)) {
return null;
}
// PREG_OFFSET_CAPTURE always returns the byte offset, not the char offset, which is annoying
$charPos = \mb_strlen(\mb_strcut($string, 0, $matches[0][1], 'UTF-8'), 'UTF-8');
return $offset + $charPos;
}
/**
* Functional wrapper around preg_match_all which only returns the first set of matches
*
* @psalm-param non-empty-string $pattern
*
* @return string[]|null
*
* @psalm-pure
*/
public static function matchFirst(string $pattern, string $subject, int $offset = 0): ?array
{
if ($offset !== 0) {
$subject = \substr($subject, $offset);
}
\preg_match_all($pattern, $subject, $matches, \PREG_SET_ORDER);
if ($matches === []) {
return null;
}
return $matches[0] ?: null;
}
/**
* Replace backslash escapes with literal characters
*
* @psalm-pure
*/
public static function unescape(string $string): string
{
$allEscapedChar = '/\\\\(' . self::PARTIAL_ESCAPABLE . ')/';
$escaped = \preg_replace($allEscapedChar, '$1', $string);
\assert(\is_string($escaped));
return \preg_replace_callback('/' . self::PARTIAL_ENTITY . '/i', static fn ($e) => Html5EntityDecoder::decode($e[0]), $escaped);
}
/**
* @internal
*
* @param int $type HTML block type
*
* @psalm-param HtmlBlock::TYPE_* $type
*
* @phpstan-param HtmlBlock::TYPE_* $type
*
* @psalm-return non-empty-string
*
* @throws InvalidArgumentException if an invalid type is given
*
* @psalm-pure
*/
public static function getHtmlBlockOpenRegex(int $type): string
{
switch ($type) {
case HtmlBlock::TYPE_1_CODE_CONTAINER:
return '/^<(?:script|pre|textarea|style)(?:\s|>|$)/i';
case HtmlBlock::TYPE_2_COMMENT:
return '/^<!--/';
case HtmlBlock::TYPE_3:
return '/^<[?]/';
case HtmlBlock::TYPE_4:
return '/^<![A-Z]/i';
case HtmlBlock::TYPE_5_CDATA:
return '/^<!\[CDATA\[/i';
case HtmlBlock::TYPE_6_BLOCK_ELEMENT:
return '%^<[/]?(?:address|article|aside|base|basefont|blockquote|body|caption|center|col|colgroup|dd|details|dialog|dir|div|dl|dt|fieldset|figcaption|figure|footer|form|frame|frameset|h[123456]|head|header|hr|html|iframe|legend|li|link|main|menu|menuitem|nav|noframes|ol|optgroup|option|p|param|section|source|summary|table|tbody|td|tfoot|th|thead|title|tr|track|ul)(?:\s|[/]?[>]|$)%i';
case HtmlBlock::TYPE_7_MISC_ELEMENT:
return '/^(?:' . self::PARTIAL_OPENTAG . '|' . self::PARTIAL_CLOSETAG . ')\\s*$/i';
default:
throw new InvalidArgumentException('Invalid HTML block type');
}
}
/**
* @internal
*
* @param int $type HTML block type
*
* @psalm-param HtmlBlock::TYPE_* $type
*
* @phpstan-param HtmlBlock::TYPE_* $type
*
* @psalm-return non-empty-string
*
* @throws InvalidArgumentException if an invalid type is given
*
* @psalm-pure
*/
public static function getHtmlBlockCloseRegex(int $type): string
{
switch ($type) {
case HtmlBlock::TYPE_1_CODE_CONTAINER:
return '%<\/(?:script|pre|textarea|style)>%i';
case HtmlBlock::TYPE_2_COMMENT:
return '/-->/';
case HtmlBlock::TYPE_3:
return '/\?>/';
case HtmlBlock::TYPE_4:
return '/>/';
case HtmlBlock::TYPE_5_CDATA:
return '/\]\]>/';
default:
throw new InvalidArgumentException('Invalid HTML block type');
}
}
/**
* @psalm-pure
*/
public static function isLinkPotentiallyUnsafe(string $url): bool
{
return \preg_match(self::REGEX_UNSAFE_PROTOCOL, $url) !== 0 && \preg_match(self::REGEX_SAFE_DATA_PROTOCOL, $url) === 0;
}
}
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