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<?php
namespace Masterminds\HTML5\Parser;
use Masterminds\HTML5\Exception;
/**
* The scanner scans over a given data input to react appropriately to characters.
*/
class Scanner
{
const CHARS_HEX = 'abcdefABCDEF01234567890';
const CHARS_ALNUM = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890';
const CHARS_ALPHA = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
/**
* The string data we're parsing.
*/
private $data;
/**
* The current integer byte position we are in $data.
*/
private $char;
/**
* Length of $data; when $char === $data, we are at the end-of-file.
*/
private $EOF;
/**
* Parse errors.
*/
public $errors = array();
/**
* Create a new Scanner.
*
* @param string $data Data to parse.
* @param string $encoding The encoding to use for the data.
*
* @throws Exception If the given data cannot be encoded to UTF-8.
*/
public function __construct($data, $encoding = 'UTF-8')
{
if ($data instanceof InputStream) {
@trigger_error('InputStream objects are deprecated since version 2.4 and will be removed in 3.0. Use strings instead.', E_USER_DEPRECATED);
$data = (string) $data;
}
$data = UTF8Utils::convertToUTF8($data, $encoding);
// There is good reason to question whether it makes sense to
// do this here, since most of these checks are done during
// parsing, and since this check doesn't actually *do* anything.
$this->errors = UTF8Utils::checkForIllegalCodepoints($data);
$data = $this->replaceLinefeeds($data);
$this->data = $data;
$this->char = 0;
$this->EOF = strlen($data);
}
/**
* Check if upcomming chars match the given sequence.
*
* This will read the stream for the $sequence. If it's
* found, this will return true. If not, return false.
* Since this unconsumes any chars it reads, the caller
* will still need to read the next sequence, even if
* this returns true.
*
* Example: $this->scanner->sequenceMatches('</script>') will
* see if the input stream is at the start of a
* '</script>' string.
*
* @param string $sequence
* @param bool $caseSensitive
*
* @return bool
*/
public function sequenceMatches($sequence, $caseSensitive = true)
{
$portion = substr($this->data, $this->char, strlen($sequence));
return $caseSensitive ? $portion === $sequence : 0 === strcasecmp($portion, $sequence);
}
/**
* Get the current position.
*
* @return int The current intiger byte position.
*/
public function position()
{
return $this->char;
}
/**
* Take a peek at the next character in the data.
*
* @return string The next character.
*/
public function peek()
{
if (($this->char + 1) < $this->EOF) {
return $this->data[$this->char + 1];
}
return false;
}
/**
* Get the next character.
* Note: This advances the pointer.
*
* @return string The next character.
*/
public function next()
{
++$this->char;
if ($this->char < $this->EOF) {
return $this->data[$this->char];
}
return false;
}
/**
* Get the current character.
* Note, this does not advance the pointer.
*
* @return string The current character.
*/
public function current()
{
if ($this->char < $this->EOF) {
return $this->data[$this->char];
}
return false;
}
/**
* Silently consume N chars.
*
* @param int $count
*/
public function consume($count = 1)
{
$this->char += $count;
}
/**
* Unconsume some of the data.
* This moves the data pointer backwards.
*
* @param int $howMany The number of characters to move the pointer back.
*/
public function unconsume($howMany = 1)
{
if (($this->char - $howMany) >= 0) {
$this->char -= $howMany;
}
}
/**
* Get the next group of that contains hex characters.
* Note, along with getting the characters the pointer in the data will be
* moved as well.
*
* @return string The next group that is hex characters.
*/
public function getHex()
{
return $this->doCharsWhile(static::CHARS_HEX);
}
/**
* Get the next group of characters that are ASCII Alpha characters.
* Note, along with getting the characters the pointer in the data will be
* moved as well.
*
* @return string The next group of ASCII alpha characters.
*/
public function getAsciiAlpha()
{
return $this->doCharsWhile(static::CHARS_ALPHA);
}
/**
* Get the next group of characters that are ASCII Alpha characters and numbers.
* Note, along with getting the characters the pointer in the data will be
* moved as well.
*
* @return string The next group of ASCII alpha characters and numbers.
*/
public function getAsciiAlphaNum()
{
return $this->doCharsWhile(static::CHARS_ALNUM);
}
/**
* Get the next group of numbers.
* Note, along with getting the characters the pointer in the data will be
* moved as well.
*
* @return string The next group of numbers.
*/
public function getNumeric()
{
return $this->doCharsWhile('0123456789');
}
/**
* Consume whitespace.
* Whitespace in HTML5 is: formfeed, tab, newline, space.
*
* @return int The length of the matched whitespaces.
*/
public function whitespace()
{
if ($this->char >= $this->EOF) {
return false;
}
$len = strspn($this->data, "\n\t\f ", $this->char);
$this->char += $len;
return $len;
}
/**
* Returns the current line that is being consumed.
*
* @return int The current line number.
*/
public function currentLine()
{
if (empty($this->EOF) || 0 === $this->char) {
return 1;
}
// Add one to $this->char because we want the number for the next
// byte to be processed.
return substr_count($this->data, "\n", 0, min($this->char, $this->EOF)) + 1;
}
/**
* Read chars until something in the mask is encountered.
*
* @param string $mask
*
* @return mixed
*/
public function charsUntil($mask)
{
return $this->doCharsUntil($mask);
}
/**
* Read chars as long as the mask matches.
*
* @param string $mask
*
* @return int
*/
public function charsWhile($mask)
{
return $this->doCharsWhile($mask);
}
/**
* Returns the current column of the current line that the tokenizer is at.
*
* Newlines are column 0. The first char after a newline is column 1.
*
* @return int The column number.
*/
public function columnOffset()
{
// Short circuit for the first char.
if (0 === $this->char) {
return 0;
}
// strrpos is weird, and the offset needs to be negative for what we
// want (i.e., the last \n before $this->char). This needs to not have
// one (to make it point to the next character, the one we want the
// position of) added to it because strrpos's behaviour includes the
// final offset byte.
$backwardFrom = $this->char - 1 - strlen($this->data);
$lastLine = strrpos($this->data, "\n", $backwardFrom);
// However, for here we want the length up until the next byte to be
// processed, so add one to the current byte ($this->char).
if (false !== $lastLine) {
$findLengthOf = substr($this->data, $lastLine + 1, $this->char - 1 - $lastLine);
} else {
// After a newline.
$findLengthOf = substr($this->data, 0, $this->char);
}
return UTF8Utils::countChars($findLengthOf);
}
/**
* Get all characters until EOF.
*
* This consumes characters until the EOF.
*
* @return int The number of characters remaining.
*/
public function remainingChars()
{
if ($this->char < $this->EOF) {
$data = substr($this->data, $this->char);
$this->char = $this->EOF;
return $data;
}
return ''; // false;
}
/**
* Replace linefeed characters according to the spec.
*
* @param $data
*
* @return string
*/
private function replaceLinefeeds($data)
{
/*
* U+000D CARRIAGE RETURN (CR) characters and U+000A LINE FEED (LF) characters are treated specially.
* Any CR characters that are followed by LF characters must be removed, and any CR characters not
* followed by LF characters must be converted to LF characters. Thus, newlines in HTML DOMs are
* represented by LF characters, and there are never any CR characters in the input to the tokenization
* stage.
*/
$crlfTable = array(
"\0" => "\xEF\xBF\xBD",
"\r\n" => "\n",
"\r" => "\n",
);
return strtr($data, $crlfTable);
}
/**
* Read to a particular match (or until $max bytes are consumed).
*
* This operates on byte sequences, not characters.
*
* Matches as far as possible until we reach a certain set of bytes
* and returns the matched substring.
*
* @param string $bytes Bytes to match.
* @param int $max Maximum number of bytes to scan.
*
* @return mixed Index or false if no match is found. You should use strong
* equality when checking the result, since index could be 0.
*/
private function doCharsUntil($bytes, $max = null)
{
if ($this->char >= $this->EOF) {
return false;
}
if (0 === $max || $max) {
$len = strcspn($this->data, $bytes, $this->char, $max);
} else {
$len = strcspn($this->data, $bytes, $this->char);
}
$string = (string) substr($this->data, $this->char, $len);
$this->char += $len;
return $string;
}
/**
* Returns the string so long as $bytes matches.
*
* Matches as far as possible with a certain set of bytes
* and returns the matched substring.
*
* @param string $bytes A mask of bytes to match. If ANY byte in this mask matches the
* current char, the pointer advances and the char is part of the
* substring.
* @param int $max The max number of chars to read.
*
* @return string
*/
private function doCharsWhile($bytes, $max = null)
{
if ($this->char >= $this->EOF) {
return false;
}
if (0 === $max || $max) {
$len = strspn($this->data, $bytes, $this->char, $max);
} else {
$len = strspn($this->data, $bytes, $this->char);
}
$string = (string) substr($this->data, $this->char, $len);
$this->char += $len;
return $string;
}
}
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