From d50b6659270e6ad9e654d44e1eed8cebd8d04f0d Mon Sep 17 00:00:00 2001
From: Bruce Wells <brucekwells@gmail.com>
Date: Mon, 26 Nov 2018 10:06:26 -0500
Subject: [PATCH] Fixed Lexor to correctly generate reverse polish notation
 (#33)

* Updated from NeonXP/MathExecutor

* Fixed function in () block issue
---
 README.md                 |   7 +-
 src/NXP/Classes/Lexer.php | 263 +++++++++++++++++++-------------------
 tests/MathTest.php        |  14 ++
 3 files changed, 151 insertions(+), 133 deletions(-)

diff --git a/README.md b/README.md
index f5bf318..c15dccb 100644
--- a/README.md
+++ b/README.md
@@ -3,18 +3,19 @@
 A simple math expressions calculator
 
 ## Features:
-* Built in support for +, -, *, / and power (^) operators
+* Built in support for +, -, *, / and power (^) operators plus ()
 * Support for user defined operators
 * Support for user defined functions
-* Unlimited varable length
+* Unlimited varable name lengths
 * String support, as function parameters or as evaluated by PHP
 * Exceptions on divide by zero, or treat as zero
 * Unary Minus
+* Pi ($pi) and Euler's number ($e) support to 11 decimal places
 
 ## Install via Composer:
 Stable branch
 ```
-composer require "nxp/math-executor" "dev-master"
+composer require "nxp/math-executor"
 ```
 
 Dev branch (currently unsupported)
diff --git a/src/NXP/Classes/Lexer.php b/src/NXP/Classes/Lexer.php
index 82b2c53..36eb43c 100644
--- a/src/NXP/Classes/Lexer.php
+++ b/src/NXP/Classes/Lexer.php
@@ -1,130 +1,133 @@
-<?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[] = $token;
-            }
-            if ($token instanceof TokenNumber) {
-                $output[] = $token;
-            }
-            if ($token instanceof TokenVariable) {
-                $output[] = $token;
-            }
-            if ($token instanceof TokenFunction) {
-                array_push($stack, $token);
-            }
-            if ($token instanceof TokenLeftBracket) {
-                array_push($stack, $token);
-            }
-            if ($token instanceof TokenComma) {
-                while (($current = array_pop($stack)) && (!$current instanceof TokenLeftBracket)) {
-                    $output[] = $current;
-                    if (empty($stack)) {
-                        throw new IncorrectExpressionException();
-                    }
-                }
-            }
-            if ($token instanceof TokenRightBracket) {
-                while (($current = array_pop($stack)) && (!$current instanceof TokenLeftBracket)) {
-                    $output[] = $current;
-                }
-                if (!empty($stack) && ($stack[count($stack)-1] instanceof TokenFunction)) {
-                    $output[] = array_pop($stack);
-                }
-            }
-
-            if ($token instanceof AbstractOperator) {
-                while (
-                    count($stack) > 0 &&
-                    ($stack[count($stack)-1] instanceof InterfaceOperator) &&
-                    ((
-                        $token->getAssociation() == AbstractOperator::LEFT_ASSOC &&
-                        $token->getPriority() <= $stack[count($stack)-1]->getPriority()
-                    ) || (
-                        $token->getAssociation() == AbstractOperator::RIGHT_ASSOC &&
-                        $token->getPriority() < $stack[count($stack)-1]->getPriority()
-                    ))
-                ) {
-                    $output[] = array_pop($stack);
-                }
-
-                array_push($stack, $token);
-            }
-        }
-        while (!empty($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\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;
+    }
+}
diff --git a/tests/MathTest.php b/tests/MathTest.php
index c5dd60d..9acdb63 100644
--- a/tests/MathTest.php
+++ b/tests/MathTest.php
@@ -69,7 +69,21 @@ class MathTest extends \PHPUnit_Framework_TestCase
             ['(2 + 2)*-2'],
             ['(2+-2)*2'],
 
+            ['1 + 2 * 3 / (min(1, 5) + 2 + 1)'],
+            ['1 + 2 * 3 / (min(1, 5) - 2 + 5)'],
+            ['1 + 2 * 3 / (min(1, 5) * 2 + 1)'],
+            ['1 + 2 * 3 / (min(1, 5) / 2 + 1)'],
+            ['1 + 2 * 3 / (min(1, 5) / 2 * 1)'],
+            ['1 + 2 * 3 / (min(1, 5) / 2 / 1)'],
+            ['1 + 2 * 3 / (3 + min(1, 5) + 2 + 1)'],
+            ['1 + 2 * 3 / (3 - min(1, 5) - 2 + 1)'],
+            ['1 + 2 * 3 / (3 * min(1, 5) * 2 + 1)'],
+            ['1 + 2 * 3 / (3 / min(1, 5) / 2 + 1)'],
+
+
             ['sin(10) * cos(50) / min(10, 20/2)'],
+            ['sin(10) * cos(50) / min(10, (20/2))'],
+            ['sin(10) * cos(50) / min(10, (max(10,20)/2))'],
 
             ['100500 * 3.5E5'],
             ['100500 * 3.5E-5'],