Stringy\Stringy

Complexity

Total Complexity

275

Size/Duplication

Total Lines	2887
Duplicated Lines	18.43 %

Coupling/Cohesion

Components	1
Dependencies	4

Test Coverage

Coverage

97.65%

Importance

Changes

0

130 Methods

Rating	Name	Duplication	Size	Complexity
B	__construct()	0	29	5
A	__toString()	0	4	1
A	append()	0	4	1
A	appendPassword()	0	6	1
A	appendUniqueIdentifier()	0	16	2
A	appendRandomString()	0	20	3
A	create()	0	4	1
A	between()	0	15	3
A	indexOf()	0	4	1
A	indexOfIgnoreCase()	0	4	1
A	substr()	0	10	2
A	length()	0	4	1
A	collapseWhitespace()	0	4	1
A	trim()	10	10	2
A	regexReplace()	0	19	3
A	containsAll()	15	15	4
A	contains()	0	10	2
A	containsAny()	15	15	4
A	count()	0	4	1
A	countSubstr()	0	11	2
A	dasherize()	0	4	1
A	delimit()	0	12	1
A	ensureLeft()	10	10	2
A	startsWith()	4	11	2
A	startsWithAny()	14	14	4
A	ensureRight()	10	10	2
A	endsWith()	4	19	2
A	endsWithAny()	14	14	4
A	first()	12	12	2
A	getEncoding()	0	4	1
A	getIterator()	0	4	1
A	chars()	0	12	2
A	at()	0	4	1
A	hasLowerCase()	0	4	1
A	matchesPattern()	0	8	2
A	hasUpperCase()	0	4	1
A	htmlDecode()	0	6	1
A	htmlEncode()	0	6	1
A	humanize()	0	6	1
A	upperCaseFirst()	14	14	1
A	indexOfLast()	0	4	1
A	indexOfLastIgnoreCase()	0	4	1
A	insert()	14	14	2
A	is()	0	11	2
A	isAlpha()	0	4	1
A	isEmpty()	0	4	1
A	isAlphanumeric()	0	4	1
A	isBlank()	0	4	1
A	isHexadecimal()	0	4	1
A	isHtml()	0	4	1
A	isEmail()	0	4	1
A	isJson()	0	10	2
A	isLowerCase()	0	8	2
A	isSerialized()	0	12	3
A	isUpperCase()	0	4	1
A	last()	12	12	2
A	lines()	3	11	2
A	longestCommonPrefix()	0	18	3
A	longestCommonSuffix()	0	18	3
C	longestCommonSubstring()	0	45	7
A	offsetExists()	0	12	2
A	offsetGet()	0	16	4
A	offsetSet()	0	5	1
A	offsetUnset()	0	5	1
A	pad()	0	17	4
A	padLeft()	0	4	1
B	applyPadding()	0	37	3
A	padRight()	0	4	1
A	padBoth()	0	6	1
A	prepend()	0	4	1
A	removeLeft()	12	12	2
A	removeRight()	12	12	2
A	repeat()	0	6	1
A	replace()	10	10	2
A	replaceAll()	10	10	2
A	replaceBeginning()	0	6	1
A	replaceEnding()	0	6	1
A	substringOf()	12	12	3
A	substringOfIgnoreCase()	12	12	3
A	lastSubstringOf()	12	12	3
A	lastSubstringOfIgnoreCase()	12	12	3
A	reverse()	0	6	1
B	safeTruncate()	0	29	5
A	shuffle()	0	6	1
A	slugify()	0	6	1
A	stripeCssMediaQueries()	0	6	1
A	stripWhitespace()	0	4	1
A	stripeEmptyHtmlTags()	0	6	1
A	utf8ify()	0	4	1
A	escape()	0	10	1
D	extractText()	19	125	16
A	removeXss()	0	12	2
A	removeHtmlBreak()	0	6	1
A	removeHtml()	0	6	1
B	slice()	0	16	5
C	split()	3	34	7
A	surround()	0	6	1
A	swapCase()	0	8	1
A	tidy()	0	6	1
A	titleize()	0	21	3
A	toLowerCase()	0	6	1
A	isBase64()	0	4	1
A	toAscii()	0	6	1
B	toBoolean()	0	24	3
A	toString()	0	4	1
A	toSpaces()	7	7	1
A	toTabs()	7	7	1
A	toTitleCase()	0	7	1
A	toUpperCase()	0	6	1
A	trimLeft()	10	10	2
A	trimRight()	10	10	2
A	truncate()	16	16	2
A	underscored()	0	4	1
A	upperCamelize()	0	4	1
B	camelize()	0	28	2
B	snakeize()	0	43	2
A	lowerCaseFirst()	9	9	1
A	shortenAfterWord()	0	6	1
A	lineWrapAfterWord()	0	12	2
B	afterFirst()	24	24	4
B	afterFirstIgnoreCase()	24	24	4
B	afterLastIgnoreCase()	25	25	4
B	afterLast()	25	25	4
B	beforeFirst()	25	25	4
B	beforeFirstIgnoreCase()	25	25	4
B	beforeLast()	25	25	4
B	beforeLastIgnoreCase()	25	25	4
A	capitalizePersonalName()	0	8	1
A	capitalizeWord()	0	10	1
C	capitalizePersonalNameByDelimiter()	10	76	9

<?php

declare(strict_types=1);

namespace Stringy;

use voku\helper\AntiXSS;
use voku\helper\EmailCheck;
use voku\helper\URLify;
use voku\helper\UTF8;

/**
 * Class Stringy
 *
 * @package Stringy
 */
class Stringy implements \Countable, \IteratorAggregate, \ArrayAccess
{
  /**
   * An instance's string.
   *
   * @var string
   */
  protected $str;

  /**
   * The string's encoding, which should be one of the mbstring module's
   * supported encodings.
   *
   * @var string
   */
  protected $encoding;

  /**
   * Initializes a Stringy object and assigns both str and encoding properties
   * the supplied values. $str is cast to a string prior to assignment, and if
   * $encoding is not specified, it defaults to mb_internal_encoding(). Throws
   * an InvalidArgumentException if the first argument is an array or object
   * without a __toString method.
   *
   * @param mixed  $str      [optional] <p>Value to modify, after being cast to string. Default: ''</p>
   * @param string $encoding [optional] <p>The character encoding.</p>
   *
   * @throws \InvalidArgumentException <p>if an array or object without a
   *         __toString method is passed as the first argument</p>
   */
  public function __construct($str = '', string $encoding = null)
  {
    if (\is_array($str)) {
      throw new \InvalidArgumentException(
          'Passed value cannot be an array'
      );
    }

    if (
        \is_object($str)
        &&
        !\method_exists($str, '__toString')
    ) {
      throw new \InvalidArgumentException(
          'Passed object must have a __toString method'
      );
    }

    // init
    UTF8::checkForSupport();

    $this->str = (string)$str;

    if ($encoding) {

The expression $encoding of type null|string is loosely compared to true; this is ambiguous if the string can be empty. You might want to explicitly use !== null instead.

      $this->encoding = $encoding;
    } else {
      $this->encoding = \mb_internal_encoding();
    }
  }

  /**
   * Returns the value in $str.
   *
   * @return string <p>The current value of the $str property.</p>
   */
  public function __toString()
  {
    return (string)$this->str;
  }

  /**
   * Returns a new string with $string appended.
   *
   * @param string $string <p>The string to append.</p>
   *
   * @return static <p>Object with appended $string.</p>
   */
  public function append(string $string): Stringy
  {
    return static::create($this->str . $string, $this->encoding);
  }

  /**
   * Append an password (limited to chars that are good readable).
   *
   * @param int $length <p>Length of the random string.</p>
   *
   * @return static <p>Object with appended password.</p>
   */
  public function appendPassword(int $length): Stringy
  {
    $possibleChars = '2346789bcdfghjkmnpqrtvwxyzBCDFGHJKLMNPQRTVWXYZ';

    return $this->appendRandomString($length, $possibleChars);
  }

  /**
   * Append an unique identifier.
   *
   * @param string|int $entropyExtra [optional] <p>Extra entropy via a string or int value.</p>
   * @param bool       $md5          [optional] <p>Return the unique identifier as md5-hash? Default: true</p>
   *
   * @return static <p>Object with appended unique identifier as md5-hash.</p>
   */
  public function appendUniqueIdentifier($entropyExtra = '', bool $md5 = true): Stringy
  {
    $uniqueHelper = \mt_rand() .
                    \session_id() .
                    ($_SERVER['REMOTE_ADDR'] ?? '') .
                    ($_SERVER['SERVER_ADDR'] ?? '') .
                    $entropyExtra;

    $uniqueString = \uniqid($uniqueHelper, true);

    if ($md5) {
      $uniqueString = \md5($uniqueString . $uniqueHelper);
    }

    return $this->append($uniqueString);
  }

  /**
   * Append an random string.
   *
   * @param int    $length        <p>Length of the random string.</p>
   * @param string $possibleChars [optional] <p>Characters string for the random selection.</p>
   *
   * @return static <p>Object with appended random string.</p>
   */
  public function appendRandomString(int $length, string $possibleChars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'): Stringy
  {
    // init
    $i = 0;
    $str = $this->str;
    $maxlength = UTF8::strlen($possibleChars, $this->encoding);

    if ($maxlength === 0) {
      return $this;
    }

    // add random chars
    while ($i < $length) {
      $char = UTF8::substr($possibleChars, random_int(0, $maxlength - 1), 1, $this->encoding);
      $str .= $char;
      $i++;
    }

    return $this->append($str);
  }

  /**
   * Creates a Stringy object and assigns both str and encoding properties
   * the supplied values. $str is cast to a string prior to assignment, and if
   * $encoding is not specified, it defaults to mb_internal_encoding(). It
   * then returns the initialized object. Throws an InvalidArgumentException
   * if the first argument is an array or object without a __toString method.
   *
   * @param  mixed  $str      [optional] <p>Value to modify, after being cast to string. Default: ''</p>
   * @param  string $encoding [optional] <p>The character encoding.</p>
   *
   * @return static <p>A Stringy object.</p>
   *
   * @throws \InvalidArgumentException <p>if an array or object without a
   *         __toString method is passed as the first argument</p>
   */
  public static function create($str = '', string $encoding = null): Stringy
  {
    return new static($str, $encoding);
  }

  /**
   * Returns the substring between $start and $end, if found, or an empty
   * string. An optional offset may be supplied from which to begin the
   * search for the start string.
   *
   * @param  string $start  <p>Delimiter marking the start of the substring.</p>
   * @param  string $end    <p>Delimiter marking the end of the substring.</p>
   * @param  int    $offset [optional] <p>Index from which to begin the search. Default: 0</p>
   *
   * @return static <p>Object whose $str is a substring between $start and $end.</p>
   */
  public function between(string $start, string $end, int $offset = 0): Stringy
  {
    $startIndex = $this->indexOf($start, $offset);
    if ($startIndex === false) {
      return static::create('', $this->encoding);
    }

    $substrIndex = $startIndex + UTF8::strlen($start, $this->encoding);
    $endIndex = $this->indexOf($end, $substrIndex);
    if ($endIndex === false) {
      return static::create('', $this->encoding);
    }

    return $this->substr($substrIndex, $endIndex - $substrIndex);
  }

  /**
   * Returns the index of the first occurrence of $needle in the string,
   * and false if not found. Accepts an optional offset from which to begin
   * the search.
   *
   * @param  string $needle <p>Substring to look for.</p>
   * @param  int    $offset [optional] <p>Offset from which to search. Default: 0</p>
   *
   * @return int|false <p>The occurrence's <strong>index</strong> if found, otherwise <strong>false</strong>.</p>
   */
  public function indexOf(string $needle, int $offset = 0)
  {
    return UTF8::strpos($this->str, $needle, $offset, $this->encoding);
  }

  /**
   * Returns the index of the first occurrence of $needle in the string,
   * and false if not found. Accepts an optional offset from which to begin
   * the search.
   *
   * @param  string $needle <p>Substring to look for.</p>
   * @param  int    $offset [optional] <p>Offset from which to search. Default: 0</p>
   *
   * @return int|false <p>The occurrence's <strong>index</strong> if found, otherwise <strong>false</strong>.</p>
   */
  public function indexOfIgnoreCase(string $needle, int $offset = 0)
  {
    return UTF8::stripos($this->str, $needle, $offset, $this->encoding);
  }

  /**
   * Returns the substring beginning at $start with the specified $length.
   * It differs from the UTF8::substr() function in that providing a $length of
   * null will return the rest of the string, rather than an empty string.
   *
   * @param int $start  <p>Position of the first character to use.</p>
   * @param int $length [optional] <p>Maximum number of characters used. Default: null</p>
   *
   * @return static <p>Object with its $str being the substring.</p>
   */
  public function substr(int $start, int $length = null): Stringy
  {
    if ($length === null) {
      $length = $this->length();
    }

    $str = UTF8::substr($this->str, $start, $length, $this->encoding);

    return static::create($str, $this->encoding);
  }

  /**
   * Returns the length of the string.
   *
   * @return int <p>The number of characters in $str given the encoding.</p>
   */
  public function length(): int
  {
    return UTF8::strlen($this->str, $this->encoding);
  }

  /**
   * Trims the string and replaces consecutive whitespace characters with a
   * single space. This includes tabs and newline characters, as well as
   * multibyte whitespace such as the thin space and ideographic space.
   *
   * @return static <p>Object with a trimmed $str and condensed whitespace.</p>
   */
  public function collapseWhitespace(): Stringy
  {
    return $this->regexReplace('[[:space:]]+', ' ')->trim();
  }

  /**
   * Returns a string with whitespace removed from the start and end of the
   * string. Supports the removal of unicode whitespace. Accepts an optional
   * string of characters to strip instead of the defaults.
   *
   * @param string $chars [optional] <p>String of characters to strip. Default: null</p>
   *
   * @return static <p>Object with a trimmed $str.</p>
   */
  public function trim(string $chars = null): Stringy

This method seems to be duplicated in your project.

  {
    if (!$chars) {

The expression $chars of type null|string is loosely compared to false; this is ambiguous if the string can be empty. You might want to explicitly use === null instead.

      $chars = '[:space:]';
    } else {
      $chars = \preg_quote($chars, '/');
    }

    return $this->regexReplace("^[$chars]+|[$chars]+\$", '');
  }

  /**
   * Replaces all occurrences of $pattern in $str by $replacement.
   *
   * @param  string $pattern     <p>The regular expression pattern.</p>
   * @param  string $replacement <p>The string to replace with.</p>
   * @param  string $options     [optional] <p>Matching conditions to be used.</p>
   * @param  string $delimiter   [optional] <p>Delimiter the the regex. Default: '/'</p>
   *
   * @return static <p>Object with the result2ing $str after the replacements.</p>
   */
  public function regexReplace(string $pattern, string $replacement, string $options = '', string $delimiter = '/'): Stringy
  {
    if ($options === 'msr') {
      $options = 'ms';
    }

    // fallback
    if (!$delimiter) {
      $delimiter = '/';
    }

    $str = (string)\preg_replace(
        $delimiter . $pattern . $delimiter . 'u' . $options,
        $replacement,
        $this->str
    );

    return static::create($str, $this->encoding);
  }

  /**
   * Returns true if the string contains all $needles, false otherwise. By
   * default the comparison is case-sensitive, but can be made insensitive by
   * setting $caseSensitive to false.
   *
   * @param  array $needles       <p>SubStrings to look for.</p>
   * @param  bool  $caseSensitive [optional] <p>Whether or not to enforce case-sensitivity. Default: true</p>
   *
   * @return bool  <p>Whether or not $str contains $needle.</p>
   */
  public function containsAll(array $needles, bool $caseSensitive = true): bool

This method seems to be duplicated in your project.

  {
    /** @noinspection IsEmptyFunctionUsageInspection */
    if (empty($needles)) {
      return false;
    }

    foreach ($needles as $needle) {
      if (!$this->contains($needle, $caseSensitive)) {
        return false;
      }
    }

    return true;
  }

  /**
   * Returns true if the string contains $needle, false otherwise. By default
   * the comparison is case-sensitive, but can be made insensitive by setting
   * $caseSensitive to false.
   *
   * @param string $needle        <p>Substring to look for.</p>
   * @param bool   $caseSensitive [optional] <p>Whether or not to enforce case-sensitivity. Default: true</p>
   *
   * @return bool   <p>Whether or not $str contains $needle.</p>
   */
  public function contains(string $needle, bool $caseSensitive = true): bool
  {
    $encoding = $this->encoding;

    if ($caseSensitive) {
      return (UTF8::strpos($this->str, $needle, 0, $encoding) !== false);
    }

    return (UTF8::stripos($this->str, $needle, 0, $encoding) !== false);
  }

  /**
   * Returns true if the string contains any $needles, false otherwise. By
   * default the comparison is case-sensitive, but can be made insensitive by
   * setting $caseSensitive to false.
   *
   * @param  array $needles       <p>SubStrings to look for.</p>
   * @param  bool  $caseSensitive [optional] <p>Whether or not to enforce case-sensitivity. Default: true</p>
   *
   * @return bool <p>Whether or not $str contains $needle.</p>
   */
  public function containsAny(array $needles, bool $caseSensitive = true): bool

This method seems to be duplicated in your project.

  {
    /** @noinspection IsEmptyFunctionUsageInspection */
    if (empty($needles)) {
      return false;
    }

    foreach ($needles as $needle) {
      if ($this->contains($needle, $caseSensitive)) {
        return true;
      }
    }

    return false;
  }

  /**
   * Returns the length of the string, implementing the countable interface.
   *
   * @return int <p>The number of characters in the string, given the encoding.</p>
   */
  public function count(): int
  {
    return $this->length();
  }

  /**
   * Returns the number of occurrences of $substring in the given string.
   * By default, the comparison is case-sensitive, but can be made insensitive
   * by setting $caseSensitive to false.
   *
   * @param  string $substring     <p>The substring to search for.</p>
   * @param  bool   $caseSensitive [optional] <p>Whether or not to enforce case-sensitivity. Default: true</p>
   *
   * @return int|false <p>This functions returns an integer or false if there isn't a string.</p>
   */
  public function countSubstr(string $substring, bool $caseSensitive = true)
  {
    if ($caseSensitive) {
      return UTF8::substr_count($this->str, $substring, 0, null, $this->encoding);
    }

    $str = UTF8::strtoupper($this->str, $this->encoding);
    $substring = UTF8::strtoupper($substring, $this->encoding);

    return UTF8::substr_count($str, $substring, 0, null, $this->encoding);
  }

  /**
   * Returns a lowercase and trimmed string separated by dashes. Dashes are
   * inserted before uppercase characters (with the exception of the first
   * character of the string), and in place of spaces as well as underscores.
   *
   * @return static <p>Object with a dasherized $str</p>
   */
  public function dasherize(): Stringy
  {
    return $this->delimit('-');
  }

  /**
   * Returns a lowercase and trimmed string separated by the given delimiter.
   * Delimiters are inserted before uppercase characters (with the exception
   * of the first character of the string), and in place of spaces, dashes,
   * and underscores. Alpha delimiters are not converted to lowercase.
   *
   * @param string $delimiter <p>Sequence used to separate parts of the string.</p>
   *
   * @return static <p>Object with a delimited $str.</p>
   */
  public function delimit(string $delimiter): Stringy
  {
    $str = $this->trim();

    $str = (string)\preg_replace('/\B([A-Z])/u', '-\1', $str);

    $str = UTF8::strtolower($str, $this->encoding);

    $str = (string)\preg_replace('/[-_\s]+/u', $delimiter, $str);

    return static::create($str, $this->encoding);
  }

  /**
   * Ensures that the string begins with $substring. If it doesn't, it's
   * prepended.
   *
   * @param string $substring <p>The substring to add if not present.</p>
   *
   * @return static <p>Object with its $str prefixed by the $substring.</p>
   */
  public function ensureLeft(string $substring): Stringy

This method seems to be duplicated in your project.

  {
    $stringy = static::create($this->str, $this->encoding);

    if (!$stringy->startsWith($substring)) {
      $stringy->str = $substring . $stringy->str;
    }

    return $stringy;
  }

  /**
   * Returns true if the string begins with $substring, false otherwise. By
   * default, the comparison is case-sensitive, but can be made insensitive
   * by setting $caseSensitive to false.
   *
   * @param  string $substring     <p>The substring to look for.</p>
   * @param  bool   $caseSensitive [optional] <p>Whether or not to enforce case-sensitivity. Default: true</p>
   *
   * @return bool   <p>Whether or not $str starts with $substring.</p>
   */
  public function startsWith(string $substring, bool $caseSensitive = true): bool
  {
    $str = $this->str;

    if (!$caseSensitive) {

This code seems to be duplicated across your project.

      $substring = UTF8::strtolower($substring, $this->encoding);
      $str = UTF8::strtolower($this->str, $this->encoding);
    }

    return UTF8::strpos($str, $substring, 0, $this->encoding) === 0;
  }

  /**
   * Returns true if the string begins with any of $substrings, false otherwise.
   * By default the comparison is case-sensitive, but can be made insensitive by
   * setting $caseSensitive to false.
   *
   * @param  array $substrings    <p>Substrings to look for.</p>
   * @param  bool  $caseSensitive [optional] <p>Whether or not to enforce case-sensitivity. Default: true</p>
   *
   * @return bool  <p>Whether or not $str starts with $substring.</p>
   */
  public function startsWithAny(array $substrings, bool $caseSensitive = true): bool

This method seems to be duplicated in your project.

  {
    if (empty($substrings)) {
      return false;
    }

    foreach ($substrings as $substring) {
      if ($this->startsWith($substring, $caseSensitive)) {
        return true;
      }
    }

    return false;
  }

  /**
   * Ensures that the string ends with $substring. If it doesn't, it's appended.
   *
   * @param string $substring <p>The substring to add if not present.</p>
   *
   * @return static <p>Object with its $str suffixed by the $substring.</p>
   */
  public function ensureRight(string $substring): Stringy

This method seems to be duplicated in your project.

  {
    $stringy = static::create($this->str, $this->encoding);

    if (!$stringy->endsWith($substring)) {
      $stringy->str .= $substring;
    }

    return $stringy;
  }

  /**
   * Returns true if the string ends with $substring, false otherwise. By
   * default, the comparison is case-sensitive, but can be made insensitive
   * by setting $caseSensitive to false.
   *
   * @param string $substring     <p>The substring to look for.</p>
   * @param bool   $caseSensitive [optional] <p>Whether or not to enforce case-sensitivity. Default: true</p>
   *
   * @return bool   <p>Whether or not $str ends with $substring.</p>
   */
  public function endsWith(string $substring, bool $caseSensitive = true): bool
  {
    $substringLength = UTF8::strlen($substring, $this->encoding);
    $strLength = $this->length();

    $endOfStr = UTF8::substr(
        $this->str,
        $strLength - $substringLength,
        $substringLength,
        $this->encoding
    );

    if (!$caseSensitive) {

This code seems to be duplicated across your project.

      $substring = UTF8::strtolower($substring, $this->encoding);
      $endOfStr = UTF8::strtolower($endOfStr, $this->encoding);

It seems like $endOfStr can also be of type false; however, voku\helper\UTF8::strtolower() does only seem to accept string, did you maybe forget to handle an error condition?

    }

    return $substring === $endOfStr;
  }

  /**
   * Returns true if the string ends with any of $substrings, false otherwise.
   * By default, the comparison is case-sensitive, but can be made insensitive
   * by setting $caseSensitive to false.
   *
   * @param string[] $substrings    <p>Substrings to look for.</p>
   * @param bool     $caseSensitive [optional] <p>Whether or not to enforce case-sensitivity. Default: true</p>
   *
   * @return bool     <p>Whether or not $str ends with $substring.</p>
   */
  public function endsWithAny(array $substrings, bool $caseSensitive = true): bool

This method seems to be duplicated in your project.

  {
    if (empty($substrings)) {
      return false;
    }

    foreach ($substrings as $substring) {
      if ($this->endsWith($substring, $caseSensitive)) {
        return true;
      }
    }

    return false;
  }

  /**
   * Returns the first $n characters of the string.
   *
   * @param int $n <p>Number of characters to retrieve from the start.</p>
   *
   * @return static <p>Object with its $str being the first $n chars.</p>
   */
  public function first(int $n): Stringy

This method seems to be duplicated in your project.

  {
    $stringy = static::create($this->str, $this->encoding);

    if ($n < 0) {
      $stringy->str = '';
    } else {
      return $stringy->substr(0, $n);
    }

    return $stringy;
  }

  /**
   * Returns the encoding used by the Stringy object.
   *
   * @return string <p>The current value of the $encoding property.</p>
   */
  public function getEncoding(): string
  {
    return $this->encoding;
  }

  /**
   * Returns a new ArrayIterator, thus implementing the IteratorAggregate
   * interface. The ArrayIterator's constructor is passed an array of chars
   * in the multibyte string. This enables the use of foreach with instances
   * of Stringy\Stringy.
   *
   * @return \ArrayIterator <p>An iterator for the characters in the string.</p>
   */
  public function getIterator(): \ArrayIterator
  {
    return new \ArrayIterator($this->chars());
  }

  /**
   * Returns an array consisting of the characters in the string.
   *
   * @return array <p>An array of string chars.</p>
   */
  public function chars(): array
  {
    // init
    $chars = [];
    $l = $this->length();

    for ($i = 0; $i < $l; $i++) {
      $chars[] = $this->at($i)->str;
    }

    return $chars;
  }

  /**
   * Returns the character at $index, with indexes starting at 0.
   *
   * @param int $index <p>Position of the character.</p>
   *
   * @return static <p>The character at $index.</p>
   */
  public function at(int $index): Stringy
  {
    return $this->substr($index, 1);
  }

  /**
   * Returns true if the string contains a lower case char, false otherwise.
   *
   * @return bool <p>Whether or not the string contains a lower case character.</p>
   */
  public function hasLowerCase(): bool
  {
    return $this->matchesPattern('.*[[:lower:]]');
  }

  /**
   * Returns true if $str matches the supplied pattern, false otherwise.
   *
   * @param string $pattern <p>Regex pattern to match against.</p>
   *
   * @return bool <p>Whether or not $str matches the pattern.</p>
   */
  protected function matchesPattern(string $pattern): bool
  {
    if (\preg_match('/' . $pattern . '/u', $this->str)) {
      return true;
    }

    return false;
  }

  /**
   * Returns true if the string contains an upper case char, false otherwise.
   *
   * @return bool <p>Whether or not the string contains an upper case character.</p>
   */
  public function hasUpperCase(): bool
  {
    return $this->matchesPattern('.*[[:upper:]]');
  }

  /**
   * Convert all HTML entities to their applicable characters.
   *
   * @param int $flags       [optional] <p>
   *                         A bitmask of one or more of the following flags, which specify how to handle quotes and
   *                         which document type to use. The default is ENT_COMPAT.
   *                         <table>
   *                         Available <i>flags</i> constants
   *                         <tr valign="top">
   *                         <td>Constant Name</td>
   *                         <td>Description</td>
   *                         </tr>
   *                         <tr valign="top">
   *                         <td><b>ENT_COMPAT</b></td>
   *                         <td>Will convert double-quotes and leave single-quotes alone.</td>
   *                         </tr>
   *                         <tr valign="top">
   *                         <td><b>ENT_QUOTES</b></td>
   *                         <td>Will convert both double and single quotes.</td>
   *                         </tr>
   *                         <tr valign="top">
   *                         <td><b>ENT_NOQUOTES</b></td>
   *                         <td>Will leave both double and single quotes unconverted.</td>
   *                         </tr>
   *                         <tr valign="top">
   *                         <td><b>ENT_HTML401</b></td>
   *                         <td>
   *                         Handle code as HTML 4.01.
   *                         </td>
   *                         </tr>
   *                         <tr valign="top">
   *                         <td><b>ENT_XML1</b></td>
   *                         <td>
   *                         Handle code as XML 1.
   *                         </td>
   *                         </tr>
   *                         <tr valign="top">
   *                         <td><b>ENT_XHTML</b></td>
   *                         <td>
   *                         Handle code as XHTML.
   *                         </td>
   *                         </tr>
   *                         <tr valign="top">
   *                         <td><b>ENT_HTML5</b></td>
   *                         <td>
   *                         Handle code as HTML 5.
   *                         </td>
   *                         </tr>
   *                         </table>
   *                         </p>
   *
   * @return static <p>Object with the resulting $str after being html decoded.</p>
   */
  public function htmlDecode(int $flags = ENT_COMPAT): Stringy
  {
    $str = UTF8::html_entity_decode($this->str, $flags, $this->encoding);

    return static::create($str, $this->encoding);
  }

  /**
   * Convert all applicable characters to HTML entities.
   *
   * @param int $flags       [optional] <p>
   *                         A bitmask of one or more of the following flags, which specify how to handle quotes and
   *                         which document type to use. The default is ENT_COMPAT.
   *                         <table>
   *                         Available <i>flags</i> constants
   *                         <tr valign="top">
   *                         <td>Constant Name</td>
   *                         <td>Description</td>
   *                         </tr>
   *                         <tr valign="top">
   *                         <td><b>ENT_COMPAT</b></td>
   *                         <td>Will convert double-quotes and leave single-quotes alone.</td>
   *                         </tr>
   *                         <tr valign="top">
   *                         <td><b>ENT_QUOTES</b></td>
   *                         <td>Will convert both double and single quotes.</td>
   *                         </tr>
   *                         <tr valign="top">
   *                         <td><b>ENT_NOQUOTES</b></td>
   *                         <td>Will leave both double and single quotes unconverted.</td>
   *                         </tr>
   *                         <tr valign="top">
   *                         <td><b>ENT_HTML401</b></td>
   *                         <td>
   *                         Handle code as HTML 4.01.
   *                         </td>
   *                         </tr>
   *                         <tr valign="top">
   *                         <td><b>ENT_XML1</b></td>
   *                         <td>
   *                         Handle code as XML 1.
   *                         </td>
   *                         </tr>
   *                         <tr valign="top">
   *                         <td><b>ENT_XHTML</b></td>
   *                         <td>
   *                         Handle code as XHTML.
   *                         </td>
   *                         </tr>
   *                         <tr valign="top">
   *                         <td><b>ENT_HTML5</b></td>
   *                         <td>
   *                         Handle code as HTML 5.
   *                         </td>
   *                         </tr>
   *                         </table>
   *                         </p>
   *
   * @return static <p>Object with the resulting $str after being html encoded.</p>
   */
  public function htmlEncode(int $flags = ENT_COMPAT): Stringy
  {
    $str = UTF8::htmlentities($this->str, $flags, $this->encoding);

    return static::create($str, $this->encoding);
  }

  /**
   * Capitalizes the first word of the string, replaces underscores with
   * spaces, and strips '_id'.
   *
   * @return static <p>Object with a humanized $str.</p>
   */
  public function humanize(): Stringy
  {
    $str = UTF8::str_replace(['_id', '_'], ['', ' '], $this->str);

    return static::create($str, $this->encoding)->trim()->upperCaseFirst();
  }

  /**
   * Converts the first character of the supplied string to upper case.
   *
   * @return static <p>Object with the first character of $str being upper case.</p>
   */
  public function upperCaseFirst(): Stringy

This method seems to be duplicated in your project.

  {
    $first = UTF8::substr($this->str, 0, 1, $this->encoding);
    $rest = UTF8::substr(
        $this->str,
        1,
        $this->length() - 1,
        $this->encoding
    );

    $str = UTF8::strtoupper($first, $this->encoding) . $rest;

It seems like $first defined by \voku\helper\UTF8::substr($this->str, 0, 1, $this->encoding) on line 865 can also be of type false; however, voku\helper\UTF8::strtoupper() does only seem to accept string, did you maybe forget to handle an error condition?

    return static::create($str, $this->encoding);
  }

  /**
   * Returns the index of the last occurrence of $needle in the string,
   * and false if not found. Accepts an optional offset from which to begin
   * the search. Offsets may be negative to count from the last character
   * in the string.
   *
   * @param  string $needle <p>Substring to look for.</p>
   * @param  int    $offset [optional] <p>Offset from which to search. Default: 0</p>
   *
   * @return int|false <p>The last occurrence's <strong>index</strong> if found, otherwise <strong>false</strong>.</p>
   */
  public function indexOfLast(string $needle, int $offset = 0)
  {
    return UTF8::strrpos($this->str, $needle, $offset, $this->encoding);
  }

  /**
   * Returns the index of the last occurrence of $needle in the string,
   * and false if not found. Accepts an optional offset from which to begin
   * the search. Offsets may be negative to count from the last character
   * in the string.
   *
   * @param  string $needle <p>Substring to look for.</p>
   * @param  int    $offset [optional] <p>Offset from which to search. Default: 0</p>
   *
   * @return int|false <p>The last occurrence's <strong>index</strong> if found, otherwise <strong>false</strong>.</p>
   */
  public function indexOfLastIgnoreCase(string $needle, int $offset = 0)
  {
    return UTF8::strripos($this->str, $needle, $offset, $this->encoding);
  }

  /**
   * Inserts $substring into the string at the $index provided.
   *
   * @param  string $substring <p>String to be inserted.</p>
   * @param  int    $index     <p>The index at which to insert the substring.</p>
   *
   * @return static <p>Object with the resulting $str after the insertion.</p>
   */
  public function insert(string $substring, int $index): Stringy

This method seems to be duplicated in your project.

  {
    $stringy = static::create($this->str, $this->encoding);
    if ($index > $stringy->length()) {
      return $stringy;
    }

    $start = UTF8::substr($stringy->str, 0, $index, $stringy->encoding);
    $end = UTF8::substr($stringy->str, $index, $stringy->length(), $stringy->encoding);

    $stringy->str = $start . $substring . $end;

    return $stringy;
  }

  /**
   * Returns true if the string contains the $pattern, otherwise false.
   *
   * WARNING: Asterisks ("*") are translated into (".*") zero-or-more regular
   * expression wildcards.
   *
   * @credit Originally from Laravel, thanks Taylor.
   *
   * @param string $pattern <p>The string or pattern to match against.</p>
   *
   * @return bool <p>Whether or not we match the provided pattern.</p>
   */
  public function is(string $pattern): bool
  {
    if ($this->toString() === $pattern) {
      return true;
    }

    $quotedPattern = \preg_quote($pattern, '/');
    $replaceWildCards = \str_replace('\*', '.*', $quotedPattern);

    return $this->matchesPattern('^' . $replaceWildCards . '\z');
  }

  /**
   * Returns true if the string contains only alphabetic chars, false otherwise.
   *
   * @return bool <p>Whether or not $str contains only alphabetic chars.</p>
   */
  public function isAlpha(): bool
  {
    return $this->matchesPattern('^[[:alpha:]]*$');
  }

  /**
   * Determine whether the string is considered to be empty.
   *
   * A variable is considered empty if it does not exist or if its value equals FALSE.
   * empty() does not generate a warning if the variable does not exist.
   *
   * @return bool <p>Whether or not $str is empty().</p>
   */
  public function isEmpty(): bool
  {
    return empty($this->str);
  }

  /**
   * Returns true if the string contains only alphabetic and numeric chars, false otherwise.
   *
   * @return bool <p>Whether or not $str contains only alphanumeric chars.</p>
   */
  public function isAlphanumeric(): bool
  {
    return $this->matchesPattern('^[[:alnum:]]*$');
  }

  /**
   * Returns true if the string contains only whitespace chars, false otherwise.
   *
   * @return bool <p>Whether or not $str contains only whitespace characters.</p>
   */
  public function isBlank(): bool
  {
    return $this->matchesPattern('^[[:space:]]*$');
  }

  /**
   * Returns true if the string contains only hexadecimal chars, false otherwise.
   *
   * @return bool <p>Whether or not $str contains only hexadecimal chars.</p>
   */
  public function isHexadecimal(): bool
  {
    return $this->matchesPattern('^[[:xdigit:]]*$');
  }

  /**
   * Returns true if the string contains HTML-Tags, false otherwise.
   *
   * @return bool <p>Whether or not $str contains HTML-Tags.</p>
   */
  public function isHtml(): bool
  {
    return UTF8::is_html($this->str);
  }

  /**
   * Returns true if the string contains a valid E-Mail address, false otherwise.
   *
   * @param bool $useExampleDomainCheck   [optional] <p>Default: false</p>
   * @param bool $useTypoInDomainCheck    [optional] <p>Default: false</p>
   * @param bool $useTemporaryDomainCheck [optional] <p>Default: false</p>
   * @param bool $useDnsCheck             [optional] <p>Default: false</p>
   *
   * @return bool <p>Whether or not $str contains a valid E-Mail address.</p>
   */
  public function isEmail(bool $useExampleDomainCheck = false, bool $useTypoInDomainCheck = false, bool $useTemporaryDomainCheck = false, bool $useDnsCheck = false): bool
  {
    return EmailCheck::isValid($this->str, $useExampleDomainCheck, $useTypoInDomainCheck, $useTemporaryDomainCheck, $useDnsCheck);
  }

  /**
   * Returns true if the string is JSON, false otherwise. Unlike json_decode
   * in PHP 5.x, this method is consistent with PHP 7 and other JSON parsers,
   * in that an empty string is not considered valid JSON.
   *
   * @return bool <p>Whether or not $str is JSON.</p>
   */
  public function isJson(): bool
  {
    if (!isset($this->str[0])) {
      return false;
    }

    \json_decode($this->str);

    return \json_last_error() === JSON_ERROR_NONE;
  }

  /**
   * Returns true if the string contains only lower case chars, false otherwise.
   *
   * @return bool <p>Whether or not $str contains only lower case characters.</p>
   */
  public function isLowerCase(): bool
  {
    if ($this->matchesPattern('^[[:lower:]]*$')) {
      return true;
    }

    return false;
  }

  /**
   * Returns true if the string is serialized, false otherwise.
   *
   * @return bool <p>Whether or not $str is serialized.</p>
   */
  public function isSerialized(): bool
  {
    if (!isset($this->str[0])) {
      return false;
    }

    /** @noinspection PhpUsageOfSilenceOperatorInspection */
    /** @noinspection UnserializeExploitsInspection */
    return $this->str === 'b:0;'
           ||
           @\unserialize($this->str) !== false;
  }

  /**
   * Returns true if the string contains only lower case chars, false
   * otherwise.
   *
   * @return bool <p>Whether or not $str contains only lower case characters.</p>
   */
  public function isUpperCase(): bool
  {
    return $this->matchesPattern('^[[:upper:]]*$');
  }

  /**
   * Returns the last $n characters of the string.
   *
   * @param int $n <p>Number of characters to retrieve from the end.</p>
   *
   * @return static <p>Object with its $str being the last $n chars.</p>
   */
  public function last(int $n): Stringy

This method seems to be duplicated in your project.

  {
    $stringy = static::create($this->str, $this->encoding);

    if ($n <= 0) {
      $stringy->str = '';
    } else {
      return $stringy->substr(-$n);
    }

    return $stringy;
  }

  /**
   * Splits on newlines and carriage returns, returning an array of Stringy
   * objects corresponding to the lines in the string.
   *
   * @return static[] <p>An array of Stringy objects.</p>
   */
  public function lines(): array
  {
    $array = \preg_split('/[\r\n]{1,2}/u', $this->str);
    /** @noinspection CallableInLoopTerminationConditionInspection */
    /** @noinspection ForeachInvariantsInspection */
    for ($i = 0; $i < \count($array); $i++) {

It seems like you are calling the size function count() as part of the test condition. You might want to compute the size beforehand, and not on each iteration.

This code seems to be duplicated across your project.

      $array[$i] = static::create($array[$i], $this->encoding);
    }

    return $array;
  }

  /**
   * Returns the longest common prefix between the string and $otherStr.
   *
   * @param string $otherStr <p>Second string for comparison.</p>
   *
   * @return static <p>Object with its $str being the longest common prefix.</p>
   */
  public function longestCommonPrefix(string $otherStr): Stringy
  {
    $encoding = $this->encoding;
    $maxLength = \min($this->length(), UTF8::strlen($otherStr, $encoding));

    $longestCommonPrefix = '';
    for ($i = 0; $i < $maxLength; $i++) {
      $char = UTF8::substr($this->str, $i, 1, $encoding);

      if ($char == UTF8::substr($otherStr, $i, 1, $encoding)) {
        $longestCommonPrefix .= $char;
      } else {
        break;
      }
    }

    return static::create($longestCommonPrefix, $encoding);
  }

  /**
   * Returns the longest common suffix between the string and $otherStr.
   *
   * @param string $otherStr <p>Second string for comparison.</p>
   *
   * @return static <p>Object with its $str being the longest common suffix.</p>
   */
  public function longestCommonSuffix(string $otherStr): Stringy
  {
    $encoding = $this->encoding;
    $maxLength = \min($this->length(), UTF8::strlen($otherStr, $encoding));

    $longestCommonSuffix = '';
    for ($i = 1; $i <= $maxLength; $i++) {
      $char = UTF8::substr($this->str, -$i, 1, $encoding);

      if ($char == UTF8::substr($otherStr, -$i, 1, $encoding)) {
        $longestCommonSuffix = $char . $longestCommonSuffix;
      } else {
        break;
      }
    }

    return static::create($longestCommonSuffix, $encoding);
  }

  /**
   * Returns the longest common substring between the string and $otherStr.
   * In the case of ties, it returns that which occurs first.
   *
   * @param string $otherStr <p>Second string for comparison.</p>
   *
   * @return static <p>Object with its $str being the longest common substring.</p>
   */
  public function longestCommonSubstring(string $otherStr): Stringy
  {
    // Uses dynamic programming to solve
    // http://en.wikipedia.org/wiki/Longest_common_substring_problem
    $encoding = $this->encoding;
    $stringy = static::create($this->str, $encoding);
    $strLength = $stringy->length();
    $otherLength = UTF8::strlen($otherStr, $encoding);

    // Return if either string is empty
    if ($strLength == 0 || $otherLength == 0) {
      $stringy->str = '';

      return $stringy;
    }

    $len = 0;
    $end = 0;
    $table = \array_fill(
        0,
        $strLength + 1,
        \array_fill(0, $otherLength + 1, 0)
    );

    for ($i = 1; $i <= $strLength; $i++) {
      for ($j = 1; $j <= $otherLength; $j++) {
        $strChar = UTF8::substr($stringy->str, $i - 1, 1, $encoding);
        $otherChar = UTF8::substr($otherStr, $j - 1, 1, $encoding);

        if ($strChar == $otherChar) {
          $table[$i][$j] = $table[$i - 1][$j - 1] + 1;
          if ($table[$i][$j] > $len) {
            $len = $table[$i][$j];
            $end = $i;
          }
        } else {
          $table[$i][$j] = 0;
        }
      }
    }

    $stringy->str = UTF8::substr($stringy->str, $end - $len, $len, $encoding);

It seems like \voku\helper\UTF8::substr($stringy->str, $end - $len, $len, $encoding) can also be of type false. However, the property $str is declared as type string. Maybe add an additional type check?

    return $stringy;
  }

  /**
   * Returns whether or not a character exists at an index. Offsets may be
   * negative to count from the last character in the string. Implements
   * part of the ArrayAccess interface.
   *
   * @param int $offset <p>The index to check.</p>
   *
   * @return boolean <p>Whether or not the index exists.</p>
   */
  public function offsetExists($offset): bool
  {
    // init
    $length = $this->length();
    $offset = (int)$offset;

    if ($offset >= 0) {
      return ($length > $offset);
    }

    return ($length >= \abs($offset));
  }

  /**
   * Returns the character at the given index. Offsets may be negative to
   * count from the last character in the string. Implements part of the
   * ArrayAccess interface, and throws an OutOfBoundsException if the index
   * does not exist.
   *
   * @param int $offset <p>The <strong>index</strong> from which to retrieve the char.</p>
   *
   * @return string <p>The character at the specified index.</p>
   *
   * @throws \OutOfBoundsException <p>If the positive or negative offset does not exist.</p>
   */
  public function offsetGet($offset): string
  {
    // init
    $offset = (int)$offset;
    $length = $this->length();

    if (
        ($offset >= 0 && $length <= $offset)
        ||
        $length < \abs($offset)
    ) {
      throw new \OutOfBoundsException('No character exists at the index');
    }

    return UTF8::substr($this->str, $offset, 1, $this->encoding);
  }

  /**
   * Implements part of the ArrayAccess interface, but throws an exception
   * when called. This maintains the immutability of Stringy objects.
   *
   * @param int   $offset <p>The index of the character.</p>
   * @param mixed $value  <p>Value to set.</p>
   *
   * @throws \Exception <p>When called.</p>
   */
  public function offsetSet($offset, $value)
  {
    // Stringy is immutable, cannot directly set char
    throw new \Exception('Stringy object is immutable, cannot modify char');
  }

  /**
   * Implements part of the ArrayAccess interface, but throws an exception
   * when called. This maintains the immutability of Stringy objects.
   *
   * @param int $offset <p>The index of the character.</p>
   *
   * @throws \Exception <p>When called.</p>
   */
  public function offsetUnset($offset)
  {
    // Don't allow directly modifying the string
    throw new \Exception('Stringy object is immutable, cannot unset char');
  }

  /**
   * Pads the string to a given length with $padStr. If length is less than
   * or equal to the length of the string, no padding takes places. The
   * default string used for padding is a space, and the default type (one of
   * 'left', 'right', 'both') is 'right'. Throws an InvalidArgumentException
   * if $padType isn't one of those 3 values.
   *
   * @param int    $length  <p>Desired string length after padding.</p>
   * @param string $padStr  [optional] <p>String used to pad, defaults to space. Default: ' '</p>
   * @param string $padType [optional] <p>One of 'left', 'right', 'both'. Default: 'right'</p>
   *
   * @return static <p>Object with a padded $str.</p>
   *
   * @throws \InvalidArgumentException <p>If $padType isn't one of 'right', 'left' or 'both'.</p>
   */
  public function pad(int $length, string $padStr = ' ', string $padType = 'right'): Stringy
  {
    if (!\in_array($padType, ['left', 'right', 'both'], true)) {
      throw new \InvalidArgumentException(
          'Pad expects $padType ' . "to be one of 'left', 'right' or 'both'"
      );
    }

    switch ($padType) {
      case 'left':
        return $this->padLeft($length, $padStr);
      case 'right':
        return $this->padRight($length, $padStr);
      default:
        return $this->padBoth($length, $padStr);
    }
  }

  /**
   * Returns a new string of a given length such that the beginning of the
   * string is padded. Alias for pad() with a $padType of 'left'.
   *
   * @param int    $length <p>Desired string length after padding.</p>
   * @param string $padStr [optional] <p>String used to pad, defaults to space. Default: ' '</p>
   *
   * @return static <p>String with left padding.</p>
   */
  public function padLeft(int $length, string $padStr = ' '): Stringy
  {
    return $this->applyPadding($length - $this->length(), 0, $padStr);
  }

  /**
   * Adds the specified amount of left and right padding to the given string.
   * The default character used is a space.
   *
   * @param int    $left   [optional] <p>Length of left padding. Default: 0</p>
   * @param int    $right  [optional] <p>Length of right padding. Default: 0</p>
   * @param string $padStr [optional] <p>String used to pad. Default: ' '</p>
   *
   * @return static <p>String with padding applied.</p>
   */
  protected function applyPadding(int $left = 0, int $right = 0, string $padStr = ' '): Stringy
  {
    $stringy = static::create($this->str, $this->encoding);

    $length = UTF8::strlen($padStr, $stringy->encoding);

    $strLength = $stringy->length();
    $paddedLength = $strLength + $left + $right;

    if (!$length || $paddedLength <= $strLength) {
      return $stringy;
    }

    $leftPadding = UTF8::substr(
        UTF8::str_repeat(
            $padStr,
            (int)\ceil($left / $length)
        ),
        0,
        $left,
        $stringy->encoding
    );

    $rightPadding = UTF8::substr(
        UTF8::str_repeat(
            $padStr,
            (int)\ceil($right / $length)
        ),
        0,
        $right,
        $stringy->encoding
    );

    $stringy->str = $leftPadding . $stringy->str . $rightPadding;

    return $stringy;
  }

  /**
   * Returns a new string of a given length such that the end of the string
   * is padded. Alias for pad() with a $padType of 'right'.
   *
   * @param int    $length <p>Desired string length after padding.</p>
   * @param string $padStr [optional] <p>String used to pad, defaults to space. Default: ' '</p>
   *
   * @return static <p>String with right padding.</p>
   */
  public function padRight(int $length, string $padStr = ' '): Stringy
  {
    return $this->applyPadding(0, $length - $this->length(), $padStr);
  }

  /**
   * Returns a new string of a given length such that both sides of the
   * string are padded. Alias for pad() with a $padType of 'both'.
   *
   * @param int    $length <p>Desired string length after padding.</p>
   * @param string $padStr [optional] <p>String used to pad, defaults to space. Default: ' '</p>
   *
   * @return static <p>String with padding applied.</p>
   */
  public function padBoth(int $length, string $padStr = ' '): Stringy
  {
    $padding = $length - $this->length();

    return $this->applyPadding((int)\floor($padding / 2), (int)\ceil($padding / 2), $padStr);
  }

  /**
   * Returns a new string starting with $string.
   *
   * @param string $string <p>The string to append.</p>
   *
   * @return static <p>Object with appended $string.</p>
   */
  public function prepend(string $string): Stringy
  {
    return static::create($string . $this->str, $this->encoding);
  }

  /**
   * Returns a new string with the prefix $substring removed, if present.
   *
   * @param string $substring <p>The prefix to remove.</p>
   *
   * @return static <p>Object having a $str without the prefix $substring.</p>
   */
  public function removeLeft(string $substring): Stringy

This method seems to be duplicated in your project.

  {
    $stringy = static::create($this->str, $this->encoding);

    if ($stringy->startsWith($substring)) {
      $substringLength = UTF8::strlen($substring, $stringy->encoding);

      return $stringy->substr($substringLength);
    }

    return $stringy;
  }

  /**
   * Returns a new string with the suffix $substring removed, if present.
   *
   * @param string $substring <p>The suffix to remove.</p>
   *
   * @return static <p>Object having a $str without the suffix $substring.</p>
   */
  public function removeRight(string $substring): Stringy

This method seems to be duplicated in your project.

  {
    $stringy = static::create($this->str, $this->encoding);

    if ($stringy->endsWith($substring)) {
      $substringLength = UTF8::strlen($substring, $stringy->encoding);

      return $stringy->substr(0, $stringy->length() - $substringLength);
    }

    return $stringy;
  }

  /**
   * Returns a repeated string given a multiplier.
   *
   * @param int $multiplier <p>The number of times to repeat the string.</p>
   *
   * @return static <p>Object with a repeated str.</p>
   */
  public function repeat(int $multiplier): Stringy
  {
    $repeated = UTF8::str_repeat($this->str, $multiplier);

    return static::create($repeated, $this->encoding);
  }

  /**
   * Replaces all occurrences of $search in $str by $replacement.
   *
   * @param string $search        <p>The needle to search for.</p>
   * @param string $replacement   <p>The string to replace with.</p>
   * @param bool   $caseSensitive [optional] <p>Whether or not to enforce case-sensitivity. Default: true</p>
   *
   * @return static <p>Object with the resulting $str after the replacements.</p>
   */
  public function replace(string $search, string $replacement, bool $caseSensitive = true): Stringy

This method seems to be duplicated in your project.

  {
    if ($caseSensitive) {
      $return = UTF8::str_replace($search, $replacement, $this->str);
    } else {
      $return = UTF8::str_ireplace($search, $replacement, $this->str);
    }

    return static::create($return);
  }

  /**
   * Replaces all occurrences of $search in $str by $replacement.
   *
   * @param array        $search        <p>The elements to search for.</p>
   * @param string|array $replacement   <p>The string to replace with.</p>
   * @param bool         $caseSensitive [optional] <p>Whether or not to enforce case-sensitivity. Default: true</p>
   *
   * @return static <p>Object with the resulting $str after the replacements.</p>
   */
  public function replaceAll(array $search, $replacement, bool $caseSensitive = true): Stringy

This method seems to be duplicated in your project.

  {
    if ($caseSensitive) {
      $return = UTF8::str_replace($search, $replacement, $this->str);
    } else {
      $return = UTF8::str_ireplace($search, $replacement, $this->str);
    }

    return static::create($return);
  }

  /**
   * Replaces all occurrences of $search from the beginning of string with $replacement.
   *
   * @param string $search      <p>The string to search for.</p>
   * @param string $replacement <p>The replacement.</p>
   *
   * @return static <p>Object with the resulting $str after the replacements.</p>
   */
  public function replaceBeginning(string $search, string $replacement): Stringy
  {
    $str = $this->regexReplace('^' . \preg_quote($search, '/'), UTF8::str_replace('\\', '\\\\', $replacement));

    return static::create($str, $this->encoding);
  }

  /**
   * Replaces all occurrences of $search from the ending of string with $replacement.
   *
   * @param string $search      <p>The string to search for.</p>
   * @param string $replacement <p>The replacement.</p>
   *
   * @return static <p>Object with the resulting $str after the replacements.</p>
   */
  public function replaceEnding(string $search, string $replacement): Stringy
  {
    $str = $this->regexReplace(\preg_quote($search, '/') . '$', UTF8::str_replace('\\', '\\\\', $replacement));

    return static::create($str, $this->encoding);
  }

  /**
   * Gets the substring after (or before via "$beforeNeedle") the first occurrence of the "$needle".
   * If no match is found returns new empty Stringy object.
   *
   * @param string $needle       <p>The string to look for.</p>
   * @param bool   $beforeNeedle [optional] <p>Default: false</p>
   *
   * @return static
   */
  public function substringOf(string $needle, bool $beforeNeedle = false): Stringy

This method seems to be duplicated in your project.

  {
    if ('' === $needle) {
      return static::create();
    }

    if (false === $part = UTF8::strstr($this->str, $needle, $beforeNeedle, $this->encoding)) {
      return static::create();
    }

    return static::create($part);
  }

  /**
   * Gets the substring after (or before via "$beforeNeedle") the first occurrence of the "$needle".
   * If no match is found returns new empty Stringy object.
   *
   * @param string $needle       <p>The string to look for.</p>
   * @param bool   $beforeNeedle [optional] <p>Default: false</p>
   *
   * @return static
   */
  public function substringOfIgnoreCase(string $needle, bool $beforeNeedle = false): Stringy

This method seems to be duplicated in your project.

  {
    if ('' === $needle) {
      return static::create();
    }

    if (false === $part = UTF8::stristr($this->str, $needle, $beforeNeedle, $this->encoding)) {
      return static::create();
    }

    return static::create($part);
  }

  /**
   * Gets the substring after (or before via "$beforeNeedle") the last occurrence of the "$needle".
   * If no match is found returns new empty Stringy object.
   *
   * @param string $needle       <p>The string to look for.</p>
   * @param bool   $beforeNeedle [optional] <p>Default: false</p>
   *
   * @return static
   */
  public function lastSubstringOf(string $needle, bool $beforeNeedle = false): Stringy

This method seems to be duplicated in your project.

  {
    if ('' === $needle) {
      return static::create();
    }

    if (false === $part = UTF8::strrchr($this->str, $needle, $beforeNeedle, $this->encoding)) {
      return static::create();
    }

    return static::create($part);
  }

  /**
   * Gets the substring after (or before via "$beforeNeedle") the last occurrence of the "$needle".
   * If no match is found returns new empty Stringy object.
   *
   * @param string $needle       <p>The string to look for.</p>
   * @param bool   $beforeNeedle [optional] <p>Default: false</p>
   *
   * @return static
   */
  public function lastSubstringOfIgnoreCase(string $needle, bool $beforeNeedle = false): Stringy

This method seems to be duplicated in your project.

  {
    if ('' === $needle) {
      return static::create();
    }

    if (false === $part = UTF8::strrichr($this->str, $needle, $beforeNeedle, $this->encoding)) {
      return static::create();
    }

    return static::create($part);
  }

  /**
   * Returns a reversed string. A multibyte version of strrev().
   *
   * @return static <p>Object with a reversed $str.</p>
   */
  public function reverse(): Stringy
  {
    $reversed = UTF8::strrev($this->str);

    return static::create($reversed, $this->encoding);
  }

  /**
   * Truncates the string to a given length, while ensuring that it does not
   * split words. If $substring is provided, and truncating occurs, the
   * string is further truncated so that the substring may be appended without
   * exceeding the desired length.
   *
   * @param int    $length    <p>Desired length of the truncated string.</p>
   * @param string $substring [optional] <p>The substring to append if it can fit. Default: ''</p>
   *
   * @return static <p>Object with the resulting $str after truncating.</p>
   */
  public function safeTruncate(int $length, string $substring = ''): Stringy
  {
    $stringy = static::create($this->str, $this->encoding);
    if ($length >= $stringy->length()) {
      return $stringy;
    }

    // need to further trim the string so we can append the substring
    $encoding = $stringy->encoding;
    $substringLength = UTF8::strlen($substring, $encoding);
    $length -= $substringLength;

    $truncated = UTF8::substr($stringy->str, 0, $length, $encoding);

    // if the last word was truncated
    $strPosSpace = UTF8::strpos($stringy->str, ' ', $length - 1, $encoding);
    if ($strPosSpace != $length) {
      // find pos of the last occurrence of a space, get up to that
      $lastPos = UTF8::strrpos($truncated, ' ', 0, $encoding);

It seems like $truncated defined by \voku\helper\UTF8::substr($stringy->str, 0, $length, $encoding) on line 1704 can also be of type false; however, voku\helper\UTF8::strrpos() does only seem to accept string, did you maybe forget to handle an error condition?

      if ($lastPos !== false || $strPosSpace !== false) {
        $truncated = UTF8::substr($truncated, 0, (int)$lastPos, $encoding);

It seems like $truncated defined by \voku\helper\UTF8::substr($truncated, 0, (int) $lastPos, $encoding) on line 1713 can also be of type false; however, voku\helper\UTF8::substr() does only seem to accept string, did you maybe forget to handle an error condition?

      }
    }

    $stringy->str = $truncated . $substring;

    return $stringy;
  }

  /**
   * A multibyte string shuffle function. It returns a string with its
   * characters in random order.
   *
   * @return static <p>Object with a shuffled $str.</p>
   */
  public function shuffle(): Stringy
  {
    $shuffledStr = UTF8::str_shuffle($this->str);

    return static::create($shuffledStr, $this->encoding);
  }

  /**
   * Converts the string into an URL slug. This includes replacing non-ASCII
   * characters with their closest ASCII equivalents, removing remaining
   * non-ASCII and non-alphanumeric characters, and replacing whitespace with
   * $replacement. The replacement defaults to a single dash, and the string
   * is also converted to lowercase.
   *
   * @param string $replacement [optional] <p>The string used to replace whitespace. Default: '-'</p>
   * @param string $language    [optional] <p>The language for the url. Default: 'de'</p>
   * @param bool   $strToLower  [optional] <p>string to lower. Default: true</p>
   *
   * @return static <p>Object whose $str has been converted to an URL slug.</p>
   */
  public function slugify(string $replacement = '-', string $language = 'de', bool $strToLower = true): Stringy
  {
    $slug = URLify::slug($this->str, $language, $replacement, $strToLower);

    return static::create($slug, $this->encoding);
  }

  /**
   * Remove css media-queries.
   *
   * @return static
   */
  public function stripeCssMediaQueries(): Stringy
  {
    $pattern = '#@media\\s+(?:only\\s)?(?:[\\s{\\(]|screen|all)\\s?[^{]+{.*}\\s*}\\s*#misU';

    return static::create(\preg_replace($pattern, '', $this->str));
  }

  /**
   * Strip all whitespace characters. This includes tabs and newline characters,
   * as well as multibyte whitespace such as the thin space and ideographic space.
   *
   * @return static
   */
  public function stripWhitespace(): Stringy
  {
    return static::create(UTF8::strip_whitespace($this->str));
  }

  /**
   * Remove empty html-tag.
   *
   * e.g.: <tag></tag>
   *
   * @return static
   */
  public function stripeEmptyHtmlTags(): Stringy
  {
    $pattern = "/<[^\/>]*>(([\s]?)*|)<\/[^>]*>/i";

    return static::create(\preg_replace($pattern, '', $this->str));
  }

  /**
   * Converts the string into an valid UTF-8 string.
   *
   * @return static
   */
  public function utf8ify(): Stringy
  {
    return static::create(UTF8::cleanup($this->str));
  }

  /**
   * Create a escape html version of the string via "UTF8::htmlspecialchars()".
   *
   * @return static
   */
  public function escape(): Stringy
  {
    $str = UTF8::htmlspecialchars(
        $this->str,
        ENT_QUOTES | ENT_SUBSTITUTE,
        $this->encoding
    );

    return static::create($str, $this->encoding);
  }

  /**
   * Create an extract from a sentence, so if the search-string was found, it try to centered in the output.
   *
   * @param string   $search
   * @param int|null $length                 [optional] <p>Default: null === text->length / 2</p>
   * @param string   $replacerForSkippedText [optional] <p>Default: …</p>
   *
   * @return static
   */
  public function extractText(string $search = '', int $length = null, string $replacerForSkippedText = '…'): Stringy
  {
    // init
    $text = $this->str;

    if (empty($text)) {
      return static::create('', $this->encoding);
    }

    $trimChars = "\t\r\n -_()!~?=+/*\\,.:;\"'[]{}`&";

    if ($length === null) {
      $length = (int)\round($this->length() / 2, 0);
    }

    if (empty($search)) {

      $stringLength = UTF8::strlen($text, $this->encoding);

      if ($length > 0) {
        $end = ($length - 1) > $stringLength ? $stringLength : ($length - 1);
      } else {
        $end = 0;
      }

      $pos = \min(
          UTF8::strpos($text, ' ', $end, $this->encoding),
          UTF8::strpos($text, '.', $end, $this->encoding)
      );

      if ($pos) {
        return static::create(
            \rtrim(
                UTF8::substr($text, 0, $pos, $this->encoding),
                $trimChars
            ) . $replacerForSkippedText,
            $this->encoding
        );
      }

      return static::create($text, $this->encoding);
    }

    $wordPos = UTF8::stripos(
        $text,
        $search,
        0,
        $this->encoding
    );
    $halfSide = (int)($wordPos - $length / 2 + UTF8::strlen($search, $this->encoding) / 2);

    if ($halfSide > 0) {

      $halfText = UTF8::substr($text, 0, $halfSide, $this->encoding);
      $pos_start = \max(UTF8::strrpos($halfText, ' ', 0), UTF8::strrpos($halfText, '.', 0));

It seems like $halfText defined by \voku\helper\UTF8::substr($text, 0, $halfSide, $this->encoding) on line 1880 can also be of type false; however, voku\helper\UTF8::strrpos() does only seem to accept string, did you maybe forget to handle an error condition?

      if (!$pos_start) {
        $pos_start = 0;
      }

    } else {
      $pos_start = 0;
    }

    if ($wordPos && $halfSide > 0) {
      $l = $pos_start + $length - 1;
      $realLength = UTF8::strlen($text, $this->encoding);

      if ($l > $realLength) {
        $l = $realLength;
      }

      $pos_end = \min(
                     UTF8::strpos($text, ' ', $l, $this->encoding),
                     UTF8::strpos($text, '.', $l, $this->encoding)
                 ) - $pos_start;

      if (!$pos_end || $pos_end <= 0) {
        $extract = $replacerForSkippedText . \ltrim(
                UTF8::substr(
                    $text,
                    $pos_start,
                    UTF8::strlen($text),
                    $this->encoding
                ),
                $trimChars
            );
      } else {

This code seems to be duplicated across your project.

        $extract = $replacerForSkippedText . \trim(
                UTF8::substr(
                    $text,
                    $pos_start,
                    $pos_end,
                    $this->encoding
                ),
                $trimChars
            ) . $replacerForSkippedText;
      }

    } else {

      $l = $length - 1;
      $trueLength = UTF8::strlen($text, $this->encoding);

      if ($l > $trueLength) {
        $l = $trueLength;
      }

      $pos_end = \min(
          UTF8::strpos($text, ' ', $l, $this->encoding),
          UTF8::strpos($text, '.', $l, $this->encoding)
      );

      if ($pos_end) {

This code seems to be duplicated across your project.

        $extract = \rtrim(
                       UTF8::substr($text, 0, $pos_end, $this->encoding),
                       $trimChars
                   ) . $replacerForSkippedText;
      } else {
        $extract = $text;
      }
    }

    return static::create($extract, $this->encoding);
  }


  /**
   * Try to remove all XSS-attacks from the string.
   *
   * @return static
   */
  public function removeXss(): Stringy
  {
    static $antiXss = null;

    if ($antiXss === null) {
      $antiXss = new AntiXSS();
    }

    $str = $antiXss->xss_clean($this->str);

    return static::create($str, $this->encoding);
  }

  /**
   * Remove all breaks [<br> | \r\n | \r | \n | ...] from the string.
   *
   * @param string $replacement [optional] <p>Default is a empty string.</p>
   *
   * @return static
   */
  public function removeHtmlBreak(string $replacement = ''): Stringy
  {
    $str = (string)\preg_replace('#/\r\n|\r|\n|<br.*/?>#isU', $replacement, $this->str);

    return static::create($str, $this->encoding);
  }

  /**
   * Remove html via "strip_tags()" from the string.
   *
   * @param string $allowableTags [optional] <p>You can use the optional second parameter to specify tags which should
   *                              not be stripped. Default: null
   *                              </p>
   *
   * @return static
   */
  public function removeHtml(string $allowableTags = null): Stringy
  {
    $str = \strip_tags($this->str, $allowableTags);

    return static::create($str, $this->encoding);
  }

  /**
   * Returns the substring beginning at $start, and up to, but not including
   * the index specified by $end. If $end is omitted, the function extracts
   * the remaining string. If $end is negative, it is computed from the end
   * of the string.
   *
   * @param int $start <p>Initial index from which to begin extraction.</p>
   * @param int $end   [optional] <p>Index at which to end extraction. Default: null</p>
   *
   * @return static <p>Object with its $str being the extracted substring.</p>
   */
  public function slice(int $start, int $end = null): Stringy
  {
    if ($end === null) {
      $length = $this->length();
    } elseif ($end >= 0 && $end <= $start) {
      return static::create('', $this->encoding);
    } elseif ($end < 0) {
      $length = $this->length() + $end - $start;
    } else {
      $length = $end - $start;
    }

    $str = UTF8::substr($this->str, $start, $length, $this->encoding);

    return static::create($str, $this->encoding);
  }

  /**
   * Splits the string with the provided regular expression, returning an
   * array of Stringy objects. An optional integer $limit will truncate the
   * results.
   *
   * @param string $pattern <p>The regex with which to split the string.</p>
   * @param int    $limit   [optional] <p>Maximum number of results to return. Default: -1 === no limit</p>
   *
   * @return static[] <p>An array of Stringy objects.</p>
   */
  public function split(string $pattern, int $limit = -1): array
  {
    if ($limit === 0) {
      return [];
    }

    // this->split errors when supplied an empty pattern in < PHP 5.4.13
    // and current versions of HHVM (3.8 and below)
    if ($pattern === '') {
      return [static::create($this->str, $this->encoding)];
    }

    // this->split returns the remaining unsplit string in the last index when
    // supplying a limit
    if ($limit > 0) {
      $limit += 1;
    } else {
      $limit = -1;
    }

    $array = \preg_split('/' . \preg_quote($pattern, '/') . '/u', $this->str, $limit);

    if ($limit > 0 && \count($array) === $limit) {
      \array_pop($array);
    }

    /** @noinspection CallableInLoopTerminationConditionInspection */
    /** @noinspection ForeachInvariantsInspection */
    for ($i = 0; $i < \count($array); $i++) {

It seems like you are calling the size function count() as part of the test condition. You might want to compute the size beforehand, and not on each iteration.

This code seems to be duplicated across your project.

      $array[$i] = static::create($array[$i], $this->encoding);
    }

    return $array;
  }

  /**
   * Surrounds $str with the given substring.
   *
   * @param string $substring <p>The substring to add to both sides.</P>
   *
   * @return static <p>Object whose $str had the substring both prepended and appended.</p>
   */
  public function surround(string $substring): Stringy
  {
    $str = \implode('', [$substring, $this->str, $substring]);

    return static::create($str, $this->encoding);
  }

  /**
   * Returns a case swapped version of the string.
   *
   * @return static <p>Object whose $str has each character's case swapped.</P>
   */
  public function swapCase(): Stringy
  {
    $stringy = static::create($this->str, $this->encoding);

    $stringy->str = UTF8::swapCase($stringy->str, $stringy->encoding);

    return $stringy;
  }

  /**
   * Returns a string with smart quotes, ellipsis characters, and dashes from
   * Windows-1252 (commonly used in Word documents) replaced by their ASCII
   * equivalents.
   *
   * @return static <p>Object whose $str has those characters removed.</p>
   */
  public function tidy(): Stringy
  {
    $str = UTF8::normalize_msword($this->str);

    return static::create($str, $this->encoding);
  }

  /**
   * Returns a trimmed string with the first letter of each word capitalized.
   * Also accepts an array, $ignore, allowing you to list words not to be
   * capitalized.
   *
   * @param array|null $ignore [optional] <p>An array of words not to capitalize or null. Default: null</p>
   *
   * @return static <p>Object with a titleized $str.</p>
   */
  public function titleize(array $ignore = null): Stringy
  {
    $stringy = static::create($this->trim(), $this->encoding);
    $encoding = $this->encoding;

    $stringy->str = (string)\preg_replace_callback(
        '/([\S]+)/u',
        function ($match) use ($encoding, $ignore) {
          if ($ignore && \in_array($match[0], $ignore, true)) {
            return $match[0];
          }

          $stringy = new static($match[0], $encoding);

          return (string)$stringy->toLowerCase()->upperCaseFirst();
        },
        $stringy->str
    );

    return $stringy;
  }

  /**
   * Converts all characters in the string to lowercase.
   *
   * @return static <p>Object with all characters of $str being lowercase.</p>
   */
  public function toLowerCase(): Stringy
  {
    $str = UTF8::strtolower($this->str, $this->encoding);

    return static::create($str, $this->encoding);
  }

  /**
   * Returns true if the string is base64 encoded, false otherwise.
   *
   * @return bool <p>Whether or not $str is base64 encoded.</p>
   */
  public function isBase64(): bool
  {
    return UTF8::is_base64($this->str);
  }

  /**
   * Returns an ASCII version of the string. A set of non-ASCII characters are
   * replaced with their closest ASCII counterparts, and the rest are removed
   * unless instructed otherwise.
   *
   * @param bool $strict [optional] <p>Use "transliterator_transliterate()" from PHP-Intl | WARNING: bad performance |
   *                     Default: false</p>
   *
   * @return static <p>Object whose $str contains only ASCII characters.</p>
   */
  public function toAscii(bool $strict = false): Stringy
  {
    $str = UTF8::to_ascii($this->str, '?', $strict);

    return static::create($str, $this->encoding);
  }

  /**
   * Returns a boolean representation of the given logical string value.
   * For example, 'true', '1', 'on' and 'yes' will return true. 'false', '0',
   * 'off', and 'no' will return false. In all instances, case is ignored.
   * For other numeric strings, their sign will determine the return value.
   * In addition, blank strings consisting of only whitespace will return
   * false. For all other strings, the return value is a result of a
   * boolean cast.
   *
   * @return bool <p>A boolean value for the string.</p>
   */
  public function toBoolean(): bool
  {
    $key = $this->toLowerCase()->str;
    $map = [
        'true'  => true,
        '1'     => true,
        'on'    => true,
        'yes'   => true,
        'false' => false,
        '0'     => false,
        'off'   => false,
        'no'    => false,
    ];

    if (\array_key_exists($key, $map)) {
      return $map[$key];
    }

    if (\is_numeric($this->str)) {
      return ((int)$this->str > 0);
    }

    return (bool)$this->regexReplace('[[:space:]]', '')->str;
  }

  /**
   * Return Stringy object as string, but you can also use (string) for automatically casting the object into a string.
   *
   * @return string
   */
  public function toString(): string
  {
    return (string)$this->str;
  }

  /**
   * Converts each tab in the string to some number of spaces, as defined by
   * $tabLength. By default, each tab is converted to 4 consecutive spaces.
   *
   * @param int $tabLength [optional] <p>Number of spaces to replace each tab with. Default: 4</p>
   *
   * @return static <p>Object whose $str has had tabs switched to spaces.</p>
   */
  public function toSpaces(int $tabLength = 4): Stringy

This method seems to be duplicated in your project.

  {
    $spaces = UTF8::str_repeat(' ', $tabLength);
    $str = UTF8::str_replace("\t", $spaces, $this->str);

    return static::create($str, $this->encoding);
  }

  /**
   * Converts each occurrence of some consecutive number of spaces, as
   * defined by $tabLength, to a tab. By default, each 4 consecutive spaces
   * are converted to a tab.
   *
   * @param int $tabLength [optional] <p>Number of spaces to replace with a tab. Default: 4</p>
   *
   * @return static <p>Object whose $str has had spaces switched to tabs.</p>
   */
  public function toTabs(int $tabLength = 4): Stringy

This method seems to be duplicated in your project.

  {
    $spaces = UTF8::str_repeat(' ', $tabLength);
    $str = UTF8::str_replace($spaces, "\t", $this->str);

    return static::create($str, $this->encoding);
  }

  /**
   * Converts the first character of each word in the string to uppercase.
   *
   * @return static  Object with all characters of $str being title-cased
   */
  public function toTitleCase(): Stringy
  {
    // "mb_convert_case()" used a polyfill from the "UTF8"-Class
    $str = \mb_convert_case($this->str, MB_CASE_TITLE, $this->encoding);

    return static::create($str, $this->encoding);
  }

  /**
   * Converts all characters in the string to uppercase.
   *
   * @return static  Object with all characters of $str being uppercase
   */
  public function toUpperCase(): Stringy
  {
    $str = UTF8::strtoupper($this->str, $this->encoding);

    return static::create($str, $this->encoding);
  }

  /**
   * Returns a string with whitespace removed from the start of the string.
   * Supports the removal of unicode whitespace. Accepts an optional
   * string of characters to strip instead of the defaults.
   *
   * @param string $chars [optional] <p>Optional string of characters to strip. Default: null</p>
   *
   * @return static <p>Object with a trimmed $str.</p>
   */
  public function trimLeft(string $chars = null): Stringy

This method seems to be duplicated in your project.

  {
    if (!$chars) {

The expression $chars of type null|string is loosely compared to false; this is ambiguous if the string can be empty. You might want to explicitly use === null instead.

      $chars = '[:space:]';
    } else {
      $chars = \preg_quote($chars, '/');
    }

    return $this->regexReplace("^[$chars]+", '');
  }

  /**
   * Returns a string with whitespace removed from the end of the string.
   * Supports the removal of unicode whitespace. Accepts an optional
   * string of characters to strip instead of the defaults.
   *
   * @param string $chars [optional] <p>Optional string of characters to strip. Default: null</p>
   *
   * @return static <p>Object with a trimmed $str.</p>
   */
  public function trimRight(string $chars = null): Stringy

This method seems to be duplicated in your project.

  {
    if (!$chars) {

The expression $chars of type null|string is loosely compared to false; this is ambiguous if the string can be empty. You might want to explicitly use === null instead.

      $chars = '[:space:]';
    } else {
      $chars = \preg_quote($chars, '/');
    }

    return $this->regexReplace("[$chars]+\$", '');
  }

  /**
   * Truncates the string to a given length. If $substring is provided, and
   * truncating occurs, the string is further truncated so that the substring
   * may be appended without exceeding the desired length.
   *
   * @param int    $length    <p>Desired length of the truncated string.</p>
   * @param string $substring [optional] <p>The substring to append if it can fit. Default: ''</p>
   *
   * @return static <p>Object with the resulting $str after truncating.</p>
   */
  public function truncate(int $length, string $substring = ''): Stringy

This method seems to be duplicated in your project.

  {
    $stringy = static::create($this->str, $this->encoding);
    if ($length >= $stringy->length()) {
      return $stringy;
    }

    // Need to further trim the string so we can append the substring
    $substringLength = UTF8::strlen($substring, $stringy->encoding);
    $length -= $substringLength;

    $truncated = UTF8::substr($stringy->str, 0, $length, $stringy->encoding);
    $stringy->str = $truncated . $substring;

    return $stringy;
  }

  /**
   * Returns a lowercase and trimmed string separated by underscores.
   * Underscores are inserted before uppercase characters (with the exception
   * of the first character of the string), and in place of spaces as well as
   * dashes.
   *
   * @return static <p>Object with an underscored $str.</p>
   */
  public function underscored(): Stringy
  {
    return $this->delimit('_');
  }

  /**
   * Returns an UpperCamelCase version of the supplied string. It trims
   * surrounding spaces, capitalizes letters following digits, spaces, dashes
   * and underscores, and removes spaces, dashes, underscores.
   *
   * @return static  <p>Object with $str in UpperCamelCase.</p>
   */
  public function upperCamelize(): Stringy
  {
    return $this->camelize()->upperCaseFirst();
  }

  /**
   * Returns a camelCase version of the string. Trims surrounding spaces,
   * capitalizes letters following digits, spaces, dashes and underscores,
   * and removes spaces, dashes, as well as underscores.
   *
   * @return static <p>Object with $str in camelCase.</p>
   */
  public function camelize(): Stringy
  {
    $encoding = $this->encoding;
    $stringy = $this->trim()->lowerCaseFirst();
    $stringy->str = (string)\preg_replace('/^[-_]+/', '', $stringy->str);

    $stringy->str = (string)\preg_replace_callback(
        '/[-_\s]+(.)?/u',
        function ($match) use ($encoding) {
          if (isset($match[1])) {
            return UTF8::strtoupper($match[1], $encoding);
          }

          return '';
        },
        $stringy->str
    );

    $stringy->str = (string)\preg_replace_callback(
        '/[\d]+(.)?/u',
        function ($match) use ($encoding) {
          return UTF8::strtoupper($match[0], $encoding);
        },
        $stringy->str
    );

    return $stringy;
  }

  /**
   * Convert a string to e.g.: "snake_case"
   *
   * @return static <p>Object with $str in snake_case.</p>
   */
  public function snakeize(): Stringy
  {
    $str = $this->str;

    $encoding = $this->encoding;
    $str = UTF8::normalize_whitespace($str);
    $str = \str_replace('-', '_', $str);

    $str = (string)\preg_replace_callback(
        '/([\d|A-Z])/u',
        function ($matches) use ($encoding) {
          $match = $matches[1];
          $matchInt = (int)$match;

          if ("$matchInt" == $match) {
            return '_' . $match . '_';
          }

          return '_' . UTF8::strtolower($match, $encoding);
        },
        $str
    );

    $str = (string)\preg_replace(
        [

            '/\s+/',      // convert spaces to "_"
            '/^\s+|\s+$/',  // trim leading & trailing spaces
            '/_+/',         // remove double "_"
        ],
        [
            '_',
            '',
            '_',
        ],
        $str
    );

    $str = UTF8::trim($str, '_'); // trim leading & trailing "_"
    $str = UTF8::trim($str); // trim leading & trailing whitespace

    return static::create($str, $this->encoding);
  }

  /**
   * Converts the first character of the string to lower case.
   *
   * @return static <p>Object with the first character of $str being lower case.</p>
   */
  public function lowerCaseFirst(): Stringy

This method seems to be duplicated in your project.

  {
    $first = UTF8::substr($this->str, 0, 1, $this->encoding);
    $rest = UTF8::substr($this->str, 1, $this->length() - 1, $this->encoding);

    $str = UTF8::strtolower($first, $this->encoding) . $rest;

It seems like $first defined by \voku\helper\UTF8::substr($this->str, 0, 1, $this->encoding) on line 2475 can also be of type false; however, voku\helper\UTF8::strtolower() does only seem to accept string, did you maybe forget to handle an error condition?

    return static::create($str, $this->encoding);
  }

  /**
   * Shorten the string after $length, but also after the next word.
   *
   * @param int    $length
   * @param string $strAddOn [optional] <p>Default: '…'</p>
   *
   * @return static
   */
  public function shortenAfterWord(int $length, string $strAddOn = '…'): Stringy
  {
    $string = UTF8::str_limit_after_word($this->str, $length, $strAddOn);

    return static::create($string);
  }

  /**
   * Line-Wrap the string after $limit, but also after the next word.
   *
   * @param int $limit
   *
   * @return static
   */
  public function lineWrapAfterWord(int $limit): Stringy
  {
    $strings = (array)\preg_split('/\\r\\n|\\r|\\n/', $this->str);

    $string = '';
    foreach ($strings as $value) {
      $string .= wordwrap($value, $limit);
      $string .= "\n";
    }

    return static::create($string);
  }

  /**
   * Gets the substring after the first occurrence of a separator.
   * If no match is found returns new empty Stringy object.
   *
   * @param string $separator
   *
   * @return static
   */
  public function afterFirst(string $separator): Stringy

This method seems to be duplicated in your project.

  {
    if ($separator === '') {
      return static::create();
    }

    if ($this->str === '') {
      return static::create();
    }

    if (($offset = $this->indexOf($separator)) === false) {
      return static::create();
    }

    return static::create(
        UTF8::substr(
            $this->str,
            $offset + UTF8::strlen($separator, $this->encoding),
            null,
            $this->encoding
        ),
        $this->encoding
    );
  }

  /**
   * Gets the substring after the first occurrence of a separator.
   * If no match is found returns new empty Stringy object.
   *
   * @param string $separator
   *
   * @return static
   */
  public function afterFirstIgnoreCase(string $separator): Stringy

This method seems to be duplicated in your project.

  {
    if ($separator === '') {
      return static::create();
    }

    if ($this->str === '') {
      return static::create();
    }

    if (($offset = $this->indexOfIgnoreCase($separator)) === false) {
      return static::create();
    }

    return static::create(
        UTF8::substr(
            $this->str,
            $offset + UTF8::strlen($separator, $this->encoding),
            null,
            $this->encoding
        ),
        $this->encoding
    );
  }

  /**
   * Gets the substring after the last occurrence of a separator.
   * If no match is found returns new empty Stringy object.
   *
   * @param string $separator
   *
   * @return static
   */
  public function afterLastIgnoreCase(string $separator): Stringy

This method seems to be duplicated in your project.

  {
    if ($separator === '') {
      return static::create();
    }

    if ($this->str === '') {
      return static::create();
    }

    $offset = $this->indexOfLastIgnoreCase($separator);
    if ($offset === false) {
      return static::create('', $this->encoding);
    }

    return static::create(
        UTF8::substr(
            $this->str,
            $offset + UTF8::strlen($separator, $this->encoding),
            null,
            $this->encoding
        ),
        $this->encoding
    );
  }

  /**
   * Gets the substring after the last occurrence of a separator.
   * If no match is found returns new empty Stringy object.
   *
   * @param string $separator
   *
   * @return static
   */
  public function afterLast(string $separator): Stringy

This method seems to be duplicated in your project.

  {
    if ($separator === '') {
      return static::create();
    }

    if ($this->str === '') {
      return static::create();
    }

    $offset = $this->indexOfLast($separator);
    if ($offset === false) {
      return static::create('', $this->encoding);
    }

    return static::create(
        UTF8::substr(
            $this->str,
            $offset + UTF8::strlen($separator, $this->encoding),
            null,
            $this->encoding
        ),
        $this->encoding
    );
  }

  /**
   * Gets the substring before the first occurrence of a separator.
   * If no match is found returns new empty Stringy object.
   *
   * @param string $separator
   *
   * @return static
   */
  public function beforeFirst(string $separator): Stringy

This method seems to be duplicated in your project.

  {
    if ($separator === '') {
      return static::create();
    }

    if ($this->str === '') {
      return static::create();
    }

    $offset = $this->indexOf($separator);
    if ($offset === false) {
      return static::create('', $this->encoding);
    }

    return static::create(
        UTF8::substr(
            $this->str,
            0,
            $offset,
            $this->encoding
        ),
        $this->encoding
    );
  }

  /**
   * Gets the substring before the first occurrence of a separator.
   * If no match is found returns new empty Stringy object.
   *
   * @param string $separator
   *
   * @return static
   */
  public function beforeFirstIgnoreCase(string $separator): Stringy

This method seems to be duplicated in your project.

  {
    if ($separator === '') {
      return static::create();
    }

    if ($this->str === '') {
      return static::create();
    }

    $offset = $this->indexOfIgnoreCase($separator);
    if ($offset === false) {
      return static::create('', $this->encoding);
    }

    return static::create(
        UTF8::substr(
            $this->str,
            0,
            $offset,
            $this->encoding
        ),
        $this->encoding
    );
  }

  /**
   * Gets the substring before the last occurrence of a separator.
   * If no match is found returns new empty Stringy object.
   *
   * @param string $separator
   *
   * @return static
   */
  public function beforeLast(string $separator): Stringy

This method seems to be duplicated in your project.

  {
    if ($separator === '') {
      return static::create();
    }

    if ($this->str === '') {
      return static::create();
    }

    $offset = $this->indexOfLast($separator);
    if ($offset === false) {
      return static::create('', $this->encoding);
    }

    return static::create(
        UTF8::substr(
            $this->str,
            0,
            $offset,
            $this->encoding
        ),
        $this->encoding
    );
  }

  /**
   * Gets the substring before the last occurrence of a separator.
   * If no match is found returns new empty Stringy object.
   *
   * @param string $separator
   *
   * @return static
   */
  public function beforeLastIgnoreCase(string $separator): Stringy

This method seems to be duplicated in your project.

  {
    if ($separator === '') {
      return static::create();
    }

    if ($this->str === '') {
      return static::create();
    }

    $offset = $this->indexOfLastIgnoreCase($separator);
    if ($offset === false) {
      return static::create('', $this->encoding);
    }

    return static::create(
        UTF8::substr(
            $this->str,
            0,
            $offset,
            $this->encoding
        ),
        $this->encoding
    );
  }

  /**
   * Returns the string with the first letter of each word capitalized,
   * except for when the word is a name which shouldn't be capitalized.
   *
   * @return static <p>Object with $str capitalized.</p>
   */
  public function capitalizePersonalName(): Stringy
  {
    $stringy = $this->collapseWhitespace();
    $stringy->str = $this->capitalizePersonalNameByDelimiter($stringy->str, ' ')->toString();
    $stringy->str = $this->capitalizePersonalNameByDelimiter($stringy->str, '-')->toString();

    return static::create($stringy, $this->encoding);
  }

  /**
   * @param string $word
   *
   * @return static <p>Object with $str capitalized.</p>
   */
  protected function capitalizeWord(string $word): Stringy
  {
    $encoding = $this->encoding;

    $firstCharacter = UTF8::substr($word, 0, 1, $encoding);
    $restOfWord = UTF8::substr($word, 1, null, $encoding);
    $firstCharacterUppercased = UTF8::strtoupper($firstCharacter, $encoding);

It seems like $firstCharacter defined by \voku\helper\UTF8::substr($word, 0, 1, $encoding) on line 2812 can also be of type false; however, voku\helper\UTF8::strtoupper() does only seem to accept string, did you maybe forget to handle an error condition?

    return static::create($firstCharacterUppercased . $restOfWord, $encoding);
  }

  /**
   * Personal names such as "Marcus Aurelius" are sometimes typed incorrectly using lowercase ("marcus aurelius").
   *
   * @param string $names
   * @param string $delimiter
   *
   * @return static
   */
  protected function capitalizePersonalNameByDelimiter(string $names, string $delimiter): Stringy
  {
    // init
    $namesArray = \explode($delimiter, $names);
    $encoding = $this->encoding;

    $specialCases = [
        'names'    => [
            'ab',
            'af',
            'al',
            'and',
            'ap',
            'bint',
            'binte',
            'da',
            'de',
            'del',
            'den',
            'der',
            'di',
            'dit',
            'ibn',
            'la',
            'mac',
            'nic',
            'of',
            'ter',
            'the',
            'und',
            'van',
            'von',
            'y',
            'zu',
        ],
        'prefixes' => [
            'al-',
            "d'",
            'ff',
            "l'",
            'mac',
            'mc',
            'nic',
        ],
    ];

    foreach ($namesArray as &$name) {
      if (\in_array($name, $specialCases['names'], true)) {
        continue;
      }

      $continue = false;

      if ($delimiter == '-') {
        foreach ($specialCases['names'] as $beginning) {

This code seems to be duplicated across your project.

          if (UTF8::strpos($name, $beginning, 0, $encoding) === 0) {
            $continue = true;
          }
        }
      }

      foreach ($specialCases['prefixes'] as $beginning) {

This code seems to be duplicated across your project.

        if (UTF8::strpos($name, $beginning, 0, $encoding) === 0) {
          $continue = true;
        }
      }

      if ($continue) {
        continue;
      }

      $name = $this->capitalizeWord($name);
    }

    return static::create(\implode($delimiter, $namesArray), $encoding);
  }
}