sync (#5)

* Documentation fixes (#34)

Fixing typos in and clarifying documentation.

* MathExecutor allow override default operators, functions and vars (#36)

* Added simple coc (#37)

* Added simple coc

* Fix

* Replaceable operators (#38)

* Updated from NeonXP/MathExecutor

* Fixed function in () block issue

* Fixing typos in and clarifying documentation.

* Syncing from origin (#3)

* Documentation fixes (#34)

Fixing typos in and clarifying documentation.

* MathExecutor allow override default operators, functions and vars (#36)

* Allow for operators to be replaced based on regex expression

* Fix md typo (#39)

* Updated from NeonXP/MathExecutor

* Fixed function in () block issue

* Fixing typos in and clarifying documentation.

* Syncing from origin (#3)

* Documentation fixes (#34)

Fixing typos in and clarifying documentation.

* MathExecutor allow override default operators, functions and vars (#36)

* Syncing to origin (#4)

* Documentation fixes (#34)

Fixing typos in and clarifying documentation.

* MathExecutor allow override default operators, functions and vars (#36)

* Added simple coc (#37)

* Added simple coc

* Fix

* Replaceable operators (#38)

* Updated from NeonXP/MathExecutor

* Fixed function in () block issue

* Fixing typos in and clarifying documentation.

* Syncing from origin (#3)

* Documentation fixes (#34)

Fixing typos in and clarifying documentation.

* MathExecutor allow override default operators, functions and vars (#36)

* Allow for operators to be replaced based on regex expression

* \\ instead of \

* Update README.md

Some small fixes

* Fix single quotes parsing (#41)

* Fix single quotes parsing
Fix e-mails
Some small fixes

* Mistake in test

* More PHP versions

* Update README.md

Deleted `dev` branch

24 files changed, 212 insertions, 175 deletions

diff --git a/src/NXP/Classes/Calculator.php b/src/NXP/Classes/Calculator.php
index 253e70c..1ceac84 100644
--- a/src/NXP/Classes/Calculator.php
+++ b/src/NXP/Classes/Calculator.php
@@ -13,13 +13,14 @@ namespace NXP\Classes;
 use NXP\Classes\Token\InterfaceOperator;
 use NXP\Classes\Token\TokenFunction;
 use NXP\Classes\Token\TokenNumber;
-use NXP\Classes\Token\TokenString;
+use NXP\Classes\Token\TokenStringSingleQuoted;
+use NXP\Classes\Token\TokenStringDoubleQuoted;
 use NXP\Classes\Token\TokenVariable;
 use NXP\Exception\IncorrectExpressionException;
 use NXP\Exception\UnknownVariableException;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 class Calculator
 {
@@ -38,7 +39,10 @@ class Calculator
             if ($token instanceof TokenNumber) {
                 array_push($stack, $token);
             }
-            if ($token instanceof TokenString) {
+            if ($token instanceof TokenStringDoubleQuoted) {
+                array_push($stack, $token);
+            }
+            if ($token instanceof TokenStringSingleQuoted) {
                 array_push($stack, $token);
             }
             if ($token instanceof TokenVariable) {
diff --git a/src/NXP/Classes/Lexer.php b/src/NXP/Classes/Lexer.php
index 36eb43c..a511c9b 100644
--- a/src/NXP/Classes/Lexer.php
+++ b/src/NXP/Classes/Lexer.php
@@ -1,133 +1,129 @@
-<?php

-/**

- * This file is part of the MathExecutor package

- *

- * (c) Alexander Kiryukhin

- *

- * For the full copyright and license information, please view the LICENSE

- * file that was distributed with this source code

- */

-

-namespace NXP\Classes;

-

-use NXP\Classes\Token\AbstractOperator;

-use NXP\Classes\Token\InterfaceOperator;

-use NXP\Classes\Token\TokenComma;

-use NXP\Classes\Token\TokenFunction;

-use NXP\Classes\Token\TokenLeftBracket;

-use NXP\Classes\Token\TokenNumber;

-use NXP\Classes\Token\TokenRightBracket;

-use NXP\Classes\Token\TokenVariable;

-use NXP\Classes\Token\TokenString;

-use NXP\Exception\IncorrectBracketsException;

-use NXP\Exception\IncorrectExpressionException;

-

-/**

- * @author Alexander Kiryukhin <alexander@symdev.org>

- */

-class Lexer

-{

-    /**

-     * @var TokenFactory

-     */

-    private $tokenFactory;

-

-    public function __construct($tokenFactory)

-    {

-        $this->tokenFactory = $tokenFactory;

-    }

-

-    /**

-     * @param  string                                      $input Source string of equation

-     * @return array                                       Tokens stream

-     * @throws \NXP\Exception\IncorrectExpressionException

-     */

-    public function stringToTokensStream($input)

-    {

-        $matches = [];

-        preg_match_all($this->tokenFactory->getTokenParserRegex(), $input, $matches);

-        $tokenFactory = $this->tokenFactory;

-        $tokensStream = array_map(

-            function ($token) use ($tokenFactory) {

-                return $tokenFactory->createToken($token);

-            },

-            $matches[0]

-        );

-

-        return $tokensStream;

-    }

-

-    /**

-     * @param  array                                       $tokensStream Tokens stream

-     * @return array                                       Array of tokens in revers polish notation

-     * @throws \NXP\Exception\IncorrectExpressionException

-     */

-    public function buildReversePolishNotation($tokensStream)

-    {

-        $output = [];

-        $stack = [];

-

-        foreach ($tokensStream as $token) {

-            if ($token instanceof TokenString) {

-                $output[] = $token;

-            }

-            elseif ($token instanceof TokenNumber) {

-                $output[] = $token;

-            }

-            elseif ($token instanceof TokenVariable) {

-                $output[] = $token;

-            }

-            elseif ($token instanceof TokenFunction) {

-                array_push($stack, $token);

-            }

-            elseif ($token instanceof AbstractOperator) {

-                // While we have something on the stack

-                while (($count = count($stack)) > 0

-                  && (

-                     // If it is a function

-                     ($stack[$count-1] instanceof TokenFunction)

-

-                     ||

-                     // Or the operator at the top of the operator stack

-                     //  has (left associative and equal precedence)

-                     //   or has greater precedence

-                     (($stack[$count-1] instanceof InterfaceOperator) &&

-                       (

-												 ($stack[$count-1]->getAssociation() == AbstractOperator::LEFT_ASSOC &&

-                           $token->getPriority() == $stack[$count-1]->getPriority())

-												 ||

-												 ($stack[$count-1]->getPriority() > $token->getPriority())

-                       )

-                      )

-										)

-

-								  // And not a left bracket

-                  && ( ! ($stack[$count-1] instanceof TokenLeftBracket)) ) {

-                    $output[] = array_pop($stack);

-                }

-

-                array_push($stack, $token);

-            }

-            elseif ($token instanceof TokenLeftBracket) {

-                array_push($stack, $token);

-            }

-            elseif ($token instanceof TokenRightBracket) {

-                while (($current = array_pop($stack)) && ( ! ($current instanceof TokenLeftBracket))) {

-                    $output[] = $current;

-                }

-                if (!empty($stack) && ($stack[count($stack)-1] instanceof TokenFunction)) {

-                    $output[] = array_pop($stack);

-                }

-            }

-        }

-        while (!empty($stack)) {

-            $token = array_pop($stack);

-            if ($token instanceof TokenLeftBracket || $token instanceof TokenRightBracket) {

-                throw new IncorrectBracketsException();

-            }

-            $output[] = $token;

-        }

-

-        return $output;

-    }

-}

+<?php
+/**
+ * This file is part of the MathExecutor package
+ *
+ * (c) Alexander Kiryukhin
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code
+ */
+
+namespace NXP\Classes;
+
+use NXP\Classes\Token\AbstractOperator;
+use NXP\Classes\Token\InterfaceOperator;
+use NXP\Classes\Token\TokenComma;
+use NXP\Classes\Token\TokenFunction;
+use NXP\Classes\Token\TokenLeftBracket;
+use NXP\Classes\Token\TokenNumber;
+use NXP\Classes\Token\TokenRightBracket;
+use NXP\Classes\Token\TokenStringSingleQuoted;
+use NXP\Classes\Token\TokenVariable;
+use NXP\Classes\Token\TokenStringDoubleQuoted;
+use NXP\Exception\IncorrectBracketsException;
+use NXP\Exception\IncorrectExpressionException;
+
+/**
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
+ */
+class Lexer
+{
+    /**
+     * @var TokenFactory
+     */
+    private $tokenFactory;
+
+    public function __construct($tokenFactory)
+    {
+        $this->tokenFactory = $tokenFactory;
+    }
+
+    /**
+     * @param  string $input Source string of equation
+     * @return array Tokens stream
+     */
+    public function stringToTokensStream($input)
+    {
+        $matches = [];
+        preg_match_all($this->tokenFactory->getTokenParserRegex(), $input, $matches);
+        $tokenFactory = $this->tokenFactory;
+        $tokensStream = array_map(
+            function ($token) use ($tokenFactory) {
+                return $tokenFactory->createToken($token);
+            },
+            $matches[0]
+        );
+
+        return $tokensStream;
+    }
+
+    /**
+     * @param  array $tokensStream Tokens stream
+     * @return array Array of tokens in revers polish notation
+     * @throws IncorrectBracketsException
+     */
+    public function buildReversePolishNotation($tokensStream)
+    {
+        $output = [];
+        $stack = [];
+
+        foreach ($tokensStream as $token) {
+            if ($token instanceof TokenStringDoubleQuoted) {
+                $output[] = $token;
+            } elseif ($token instanceof TokenStringSingleQuoted) {
+                $output[] = $token;
+            } elseif ($token instanceof TokenNumber) {
+                $output[] = $token;
+            } elseif ($token instanceof TokenVariable) {
+                $output[] = $token;
+            } elseif ($token instanceof TokenFunction) {
+                array_push($stack, $token);
+            } elseif ($token instanceof AbstractOperator) {
+                // While we have something on the stack
+                while (($count = count($stack)) > 0
+                    && (
+                        // If it is a function
+                        ($stack[$count - 1] instanceof TokenFunction)
+
+                        ||
+                        // Or the operator at the top of the operator stack
+                        //  has (left associative and equal precedence)
+                        //   or has greater precedence
+                        (($stack[$count - 1] instanceof InterfaceOperator) &&
+                            (
+                                ($stack[$count - 1]->getAssociation() == AbstractOperator::LEFT_ASSOC &&
+                                    $token->getPriority() == $stack[$count - 1]->getPriority())
+                                ||
+                                ($stack[$count - 1]->getPriority() > $token->getPriority())
+                            )
+                        )
+                    )
+
+                    // And not a left bracket
+                    && (!($stack[$count - 1] instanceof TokenLeftBracket))) {
+                    $output[] = array_pop($stack);
+                }
+
+                array_push($stack, $token);
+            } elseif ($token instanceof TokenLeftBracket) {
+                array_push($stack, $token);
+            } elseif ($token instanceof TokenRightBracket) {
+                while (($current = array_pop($stack)) && (!($current instanceof TokenLeftBracket))) {
+                    $output[] = $current;
+                }
+                if (!empty($stack) && ($stack[count($stack) - 1] instanceof TokenFunction)) {
+                    $output[] = array_pop($stack);
+                }
+            }
+        }
+        while (!empty($stack)) {
+            $token = array_pop($stack);
+            if ($token instanceof TokenLeftBracket || $token instanceof TokenRightBracket) {
+                throw new IncorrectBracketsException();
+            }
+            $output[] = $token;
+        }
+
+        return $output;
+    }
+}
diff --git a/src/NXP/Classes/Token/AbstractContainerToken.php b/src/NXP/Classes/Token/AbstractContainerToken.php
index 12d49d2..be2da5f 100644
--- a/src/NXP/Classes/Token/AbstractContainerToken.php
+++ b/src/NXP/Classes/Token/AbstractContainerToken.php
@@ -11,7 +11,7 @@
 namespace NXP\Classes\Token;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 abstract class AbstractContainerToken implements InterfaceToken
 {
diff --git a/src/NXP/Classes/Token/AbstractOperator.php b/src/NXP/Classes/Token/AbstractOperator.php
index 87634d5..8b23ad8 100644
--- a/src/NXP/Classes/Token/AbstractOperator.php
+++ b/src/NXP/Classes/Token/AbstractOperator.php
@@ -11,7 +11,7 @@
 namespace NXP\Classes\Token;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 abstract class AbstractOperator implements InterfaceToken, InterfaceOperator
 {
diff --git a/src/NXP/Classes/Token/InterfaceFunction.php b/src/NXP/Classes/Token/InterfaceFunction.php
index be867b0..a457d0e 100644
--- a/src/NXP/Classes/Token/InterfaceFunction.php
+++ b/src/NXP/Classes/Token/InterfaceFunction.php
@@ -11,7 +11,7 @@
 namespace NXP\Classes\Token;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 interface InterfaceFunction
 {
diff --git a/src/NXP/Classes/Token/InterfaceOperator.php b/src/NXP/Classes/Token/InterfaceOperator.php
index da6cdf0..9e3bae1 100644
--- a/src/NXP/Classes/Token/InterfaceOperator.php
+++ b/src/NXP/Classes/Token/InterfaceOperator.php
@@ -11,7 +11,7 @@
 namespace NXP\Classes\Token;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 interface InterfaceOperator
 {
diff --git a/src/NXP/Classes/Token/InterfaceToken.php b/src/NXP/Classes/Token/InterfaceToken.php
index 86fec91..db07aeb 100644
--- a/src/NXP/Classes/Token/InterfaceToken.php
+++ b/src/NXP/Classes/Token/InterfaceToken.php
@@ -11,7 +11,7 @@
 namespace NXP\Classes\Token;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 interface InterfaceToken
 {
diff --git a/src/NXP/Classes/Token/TokenComma.php b/src/NXP/Classes/Token/TokenComma.php
index f590e32..6a45595 100644
--- a/src/NXP/Classes/Token/TokenComma.php
+++ b/src/NXP/Classes/Token/TokenComma.php
@@ -11,7 +11,7 @@
 namespace NXP\Classes\Token;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 class TokenComma implements InterfaceToken
 {
diff --git a/src/NXP/Classes/Token/TokenDegree.php b/src/NXP/Classes/Token/TokenDegree.php
index 3eec23d..273183a 100644
--- a/src/NXP/Classes/Token/TokenDegree.php
+++ b/src/NXP/Classes/Token/TokenDegree.php
@@ -13,7 +13,7 @@ namespace NXP\Classes\Token;
 use NXP\Exception\IncorrectExpressionException;
 
 /**
-* @author Alexander Kiryukhin <alexander@symdev.org>
+* @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
 */
 class TokenDegree extends AbstractOperator
 {
diff --git a/src/NXP/Classes/Token/TokenDivision.php b/src/NXP/Classes/Token/TokenDivision.php
index 9166d34..4a8f8ce 100644
--- a/src/NXP/Classes/Token/TokenDivision.php
+++ b/src/NXP/Classes/Token/TokenDivision.php
@@ -14,7 +14,7 @@ use NXP\Exception\IncorrectExpressionException;
 use NXP\Exception\DivisionByZeroException;
 
 /**
-* @author Alexander Kiryukhin <alexander@symdev.org>
+* @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
 */
 class TokenDivision extends AbstractOperator
 {
diff --git a/src/NXP/Classes/Token/TokenFunction.php b/src/NXP/Classes/Token/TokenFunction.php
index 2ed8ace..b2866c3 100644
--- a/src/NXP/Classes/Token/TokenFunction.php
+++ b/src/NXP/Classes/Token/TokenFunction.php
@@ -11,7 +11,7 @@
 namespace NXP\Classes\Token;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 class TokenFunction extends AbstractContainerToken implements InterfaceFunction
 {
diff --git a/src/NXP/Classes/Token/TokenLeftBracket.php b/src/NXP/Classes/Token/TokenLeftBracket.php
index 0cfdc1a..08165d8 100644
--- a/src/NXP/Classes/Token/TokenLeftBracket.php
+++ b/src/NXP/Classes/Token/TokenLeftBracket.php
@@ -11,7 +11,7 @@
 namespace NXP\Classes\Token;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 class TokenLeftBracket implements InterfaceToken
 {
diff --git a/src/NXP/Classes/Token/TokenMinus.php b/src/NXP/Classes/Token/TokenMinus.php
index 566c950..ad0b8e5 100644
--- a/src/NXP/Classes/Token/TokenMinus.php
+++ b/src/NXP/Classes/Token/TokenMinus.php
@@ -13,7 +13,7 @@ namespace NXP\Classes\Token;
 use NXP\Exception\IncorrectExpressionException;
 
 /**
-* @author Alexander Kiryukhin <alexander@symdev.org>
+* @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
 */
 class TokenMinus extends AbstractOperator
 {
diff --git a/src/NXP/Classes/Token/TokenMultiply.php b/src/NXP/Classes/Token/TokenMultiply.php
index 8b173b9..0b1ecfb 100644
--- a/src/NXP/Classes/Token/TokenMultiply.php
+++ b/src/NXP/Classes/Token/TokenMultiply.php
@@ -13,7 +13,7 @@ namespace NXP\Classes\Token;
 use NXP\Exception\IncorrectExpressionException;
 
 /**
-* @author Alexander Kiryukhin <alexander@symdev.org>
+* @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
 */
 class TokenMultiply extends AbstractOperator
 {
diff --git a/src/NXP/Classes/Token/TokenNumber.php b/src/NXP/Classes/Token/TokenNumber.php
index a7eac57..982e316 100644
--- a/src/NXP/Classes/Token/TokenNumber.php
+++ b/src/NXP/Classes/Token/TokenNumber.php
@@ -11,7 +11,7 @@
 namespace NXP\Classes\Token;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 class TokenNumber extends AbstractContainerToken
 {
diff --git a/src/NXP/Classes/Token/TokenPlus.php b/src/NXP/Classes/Token/TokenPlus.php
index fe5a1d6..a6e5036 100644
--- a/src/NXP/Classes/Token/TokenPlus.php
+++ b/src/NXP/Classes/Token/TokenPlus.php
@@ -13,7 +13,7 @@ namespace NXP\Classes\Token;
 use NXP\Exception\IncorrectExpressionException;
 
 /**
-* @author Alexander Kiryukhin <alexander@symdev.org>
+* @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
 */
 class TokenPlus extends AbstractOperator
 {
diff --git a/src/NXP/Classes/Token/TokenRightBracket.php b/src/NXP/Classes/Token/TokenRightBracket.php
index c68473a..306ae0b 100644
--- a/src/NXP/Classes/Token/TokenRightBracket.php
+++ b/src/NXP/Classes/Token/TokenRightBracket.php
@@ -11,7 +11,7 @@
 namespace NXP\Classes\Token;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 class TokenRightBracket implements InterfaceToken
 {
diff --git a/src/NXP/Classes/Token/TokenString.php b/src/NXP/Classes/Token/TokenStringDoubleQuoted.php
index cab0711..6cff262 100644
--- a/src/NXP/Classes/Token/TokenString.php
+++ b/src/NXP/Classes/Token/TokenStringDoubleQuoted.php
@@ -13,7 +13,7 @@ namespace NXP\Classes\Token;
 /**
  * @author Bruce Wells <brucekwells@gmail.com>
  */
-class TokenString extends AbstractContainerToken
+class TokenStringDoubleQuoted extends AbstractContainerToken
 {
     /**
      * @return string
diff --git a/src/NXP/Classes/Token/TokenStringSingleQuoted.php b/src/NXP/Classes/Token/TokenStringSingleQuoted.php
new file mode 100644
index 0000000..7a7ab92
--- /dev/null
+++ b/src/NXP/Classes/Token/TokenStringSingleQuoted.php
@@ -0,0 +1,26 @@
+<?php
+/**
+ * This file is part of the MathExecutor package
+ *
+ * (c) Alexander Kiryukhin
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code
+ */
+
+namespace NXP\Classes\Token;
+
+/**
+ * @author Bruce Wells <brucekwells@gmail.com>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
+ */
+class TokenStringSingleQuoted extends AbstractContainerToken
+{
+    /**
+     * @return string
+     */
+    public static function getRegex()
+    {
+        return "'([^']|'')*'";
+    }
+}
diff --git a/src/NXP/Classes/Token/TokenVariable.php b/src/NXP/Classes/Token/TokenVariable.php
index ccd7c83..a4a820a 100644
--- a/src/NXP/Classes/Token/TokenVariable.php
+++ b/src/NXP/Classes/Token/TokenVariable.php
@@ -11,7 +11,7 @@
 namespace NXP\Classes\Token;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 class TokenVariable extends AbstractContainerToken
 {
diff --git a/src/NXP/Classes/TokenFactory.php b/src/NXP/Classes/TokenFactory.php
index 778cb59..74b5789 100644
--- a/src/NXP/Classes/TokenFactory.php
+++ b/src/NXP/Classes/TokenFactory.php
@@ -16,14 +16,15 @@ use NXP\Classes\Token\TokenFunction;
 use NXP\Classes\Token\TokenLeftBracket;
 use NXP\Classes\Token\TokenNumber;
 use NXP\Classes\Token\TokenRightBracket;
+use NXP\Classes\Token\TokenStringSingleQuoted;
 use NXP\Classes\Token\TokenVariable;
-use NXP\Classes\Token\TokenString;
+use NXP\Classes\Token\TokenStringDoubleQuoted;
 use NXP\Exception\UnknownFunctionException;
 use NXP\Exception\UnknownOperatorException;
 use NXP\Exception\UnknownTokenException;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 class TokenFactory
 {
@@ -77,8 +78,9 @@ class TokenFactory
 
     /**
      * Add operator
-     * @param  string                                  $operatorClass
-     * @throws \NXP\Exception\UnknownOperatorException
+     * @param  string $operatorClass
+     * @throws UnknownOperatorException
+     * @throws \ReflectionException
      */
     public function addOperator($operatorClass)
     {
@@ -135,9 +137,10 @@ class TokenFactory
         }
 
         return sprintf(
-            '/(%s)|(%s)|([%s])|(%s)|(%s)|([%s%s%s])/i',
+            '/(%s)|(%s)|(%s)|([%s])|(%s)|(%s)|([%s%s%s])/i',
             TokenNumber::getRegex(),
-            TokenString::getRegex(),
+            TokenStringDoubleQuoted::getRegex(),
+            TokenStringSingleQuoted::getRegex(),
             $operatorsRegex,
             TokenFunction::getRegex(),
             TokenVariable::getRegex(),
@@ -148,9 +151,10 @@ class TokenFactory
     }
 
     /**
-     * @param  string                $token
+     * @param  string $token
      * @return InterfaceToken
      * @throws UnknownTokenException
+     * @throws UnknownFunctionException
      */
     public function createToken($token)
     {
@@ -167,7 +171,11 @@ class TokenFactory
         }
 
         if ($token[0] == '"') {
-            return new TokenString(str_replace('"', '', $token));
+            return new TokenStringDoubleQuoted(str_replace('"', '', $token));
+        }
+
+        if ($token[0] == "'") {
+            return new TokenStringSingleQuoted(str_replace("'", '', $token));
         }
 
         if ($token == ',') {
@@ -184,7 +192,7 @@ class TokenFactory
 
         $regex = sprintf('/%s/i', TokenVariable::getRegex());
         if (preg_match($regex, $token)) {
-            return new TokenVariable(substr($token,1));
+            return new TokenVariable(substr($token, 1));
         }
 
         $regex = sprintf('/%s/i', TokenFunction::getRegex());
diff --git a/src/NXP/Exception/IncorrectBracketsException.php b/src/NXP/Exception/IncorrectBracketsException.php
index b3e8315..3b2d2b7 100644
--- a/src/NXP/Exception/IncorrectBracketsException.php
+++ b/src/NXP/Exception/IncorrectBracketsException.php
@@ -12,7 +12,7 @@
 namespace NXP\Exception;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 class IncorrectBracketsException extends MathExecutorException
 {
diff --git a/src/NXP/Exception/UnknownVariableException.php b/src/NXP/Exception/UnknownVariableException.php
index 8c215db..031a603 100644
--- a/src/NXP/Exception/UnknownVariableException.php
+++ b/src/NXP/Exception/UnknownVariableException.php
@@ -12,7 +12,7 @@
 namespace NXP\Exception;
 
 /**
- * @author Alexander Kiryukhin <alexander@symdev.org>
+ * @author Alexander Kiryukhin <a.kiryukhin@mail.ru>
  */
 class UnknownVariableException extends MathExecutorException
 {
diff --git a/src/NXP/MathExecutor.php b/src/NXP/MathExecutor.php
index 706f8af..29c6a64 100644
--- a/src/NXP/MathExecutor.php
+++ b/src/NXP/MathExecutor.php
@@ -13,7 +13,6 @@ namespace NXP;
 
 use NXP\Classes\Calculator;
 use NXP\Classes\Lexer;
-use NXP\Classes\Token;
 use NXP\Classes\TokenFactory;
 use NXP\Exception\UnknownVariableException;
 
@@ -66,13 +65,13 @@ class MathExecutor
     /**
      * Get a specific var
      *
-     * @param  string        $variable
+     * @param  string $variable
      * @return integer|float
      * @throws UnknownVariableException
      */
     public function getVar($variable)
     {
-        if (! isset($this->variables[$variable])) {
+        if (!isset($this->variables[$variable])) {
             throw new UnknownVariableException("Variable ({$variable}) not set");
         }
 
@@ -82,9 +81,10 @@ class MathExecutor
     /**
      * Add variable to executor
      *
-     * @param  string        $variable
+     * @param  string $variable
      * @param  integer|float $value
      * @return MathExecutor
+     * @throws \Exception
      */
     public function setVar($variable, $value)
     {
@@ -100,9 +100,10 @@ class MathExecutor
     /**
      * Add variables to executor
      *
-     * @param  array        $variables
-     * @param  bool         $clear     Clear previous variables
+     * @param  array $variables
+     * @param  bool $clear Clear previous variables
      * @return MathExecutor
+     * @throws \Exception
      */
     public function setVars(array $variables, $clear = true)
     {
@@ -120,7 +121,7 @@ class MathExecutor
     /**
      * Remove variable from executor
      *
-     * @param  string       $variable
+     * @param  string $variable
      * @return MathExecutor
      */
     public function removeVar($variable)
@@ -143,8 +144,9 @@ class MathExecutor
     /**
      * Add operator to executor
      *
-     * @param  string       $operatorClass Class of operator token
+     * @param  string $operatorClass Class of operator token
      * @return MathExecutor
+     * @throws Exception\UnknownOperatorException
      */
     public function addOperator($operatorClass)
     {
@@ -166,10 +168,11 @@ class MathExecutor
     /**
      * Add function to executor
      *
-     * @param  string       $name     Name of function
-     * @param  callable     $function Function
-     * @param  int          $places   Count of arguments
+     * @param  string $name Name of function
+     * @param  callable $function Function
+     * @param  int $places Count of arguments
      * @return MathExecutor
+     * @throws \ReflectionException
      */
     public function addFunction($name, $function = null, $places = 1)
     {