1 files changed, 165 insertions, 0 deletions
diff --git a/src/NXP/Classes/TokenParser.php b/src/NXP/Classes/TokenParser.php
new file mode 100644
index 0000000..f498184
--- /dev/null
+++ b/src/NXP/Classes/TokenParser.php
@@ -0,0 +1,165 @@
+<?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;
+
+class TokenParser
+{
+    const DIGIT         = 'DIGIT';
+    const CHAR          = 'CHAR';
+    const SPECIAL_CHAR  = 'SPECIAL_CHAR';
+    const LEFT_BRACKET  = 'LEFT_BRACKET';
+    const RIGHT_BRACKET = 'RIGHT_BRACKET';
+    const SPACE         = 'SPACE';
+
+    private $terms = array(
+        self::DIGIT         => '[0-9\.]',
+        self::CHAR          => '[a-z_]',
+        self::SPECIAL_CHAR  => '[\!\@\#\$\%\^\&\*\/\|\-\+\=\~]',
+        self::LEFT_BRACKET  => '\(',
+        self::RIGHT_BRACKET => '\)',
+        self::SPACE         => '\s'
+    );
+
+    const ERROR_STATE = 'ERROR_STATE';
+
+    private $transitions = array(
+        Token::NOTHING => array(
+            self::DIGIT         => Token::NUMBER,
+            self::CHAR          => Token::STRING,
+            self::SPECIAL_CHAR  => Token::OPERATOR,
+            self::LEFT_BRACKET  => Token::LEFT_BRACKET,
+            self::RIGHT_BRACKET => Token::RIGHT_BRACKET,
+            self::SPACE         => Token::NOTHING
+        ),
+        Token::STRING => array(
+            self::DIGIT         => Token::STRING,
+            self::CHAR          => Token::STRING,
+            self::SPECIAL_CHAR  => Token::OPERATOR,
+            self::LEFT_BRACKET  => Token::LEFT_BRACKET,
+            self::RIGHT_BRACKET => Token::RIGHT_BRACKET,
+            self::SPACE         => Token::NOTHING
+        ),
+        Token::NUMBER => array(
+            self::DIGIT         => Token::NUMBER,
+            self::CHAR          => self::ERROR_STATE,
+            self::SPECIAL_CHAR  => Token::OPERATOR,
+            self::LEFT_BRACKET  => Token::LEFT_BRACKET,
+            self::RIGHT_BRACKET => Token::RIGHT_BRACKET,
+            self::SPACE         => Token::NOTHING
+        ),
+        Token::OPERATOR => array(
+            self::DIGIT         => Token::NUMBER,
+            self::CHAR          => Token::STRING,
+            self::SPECIAL_CHAR  => Token::OPERATOR,
+            self::LEFT_BRACKET  => Token::LEFT_BRACKET,
+            self::RIGHT_BRACKET => Token::RIGHT_BRACKET,
+            self::SPACE         => Token::NOTHING
+        ),
+        self::ERROR_STATE => array(
+            self::DIGIT         => self::ERROR_STATE,
+            self::CHAR          => self::ERROR_STATE,
+            self::SPECIAL_CHAR  => self::ERROR_STATE,
+            self::LEFT_BRACKET  => self::ERROR_STATE,
+            self::RIGHT_BRACKET => self::ERROR_STATE,
+            self::SPACE         => self::ERROR_STATE
+        ),
+        Token::LEFT_BRACKET => array(
+            self::DIGIT         => Token::NUMBER,
+            self::CHAR          => Token::STRING,
+            self::SPECIAL_CHAR  => Token::OPERATOR,
+            self::LEFT_BRACKET  => Token::LEFT_BRACKET,
+            self::RIGHT_BRACKET => Token::RIGHT_BRACKET,
+            self::SPACE         => Token::NOTHING
+        ),
+        Token::RIGHT_BRACKET => array(
+            self::DIGIT         => Token::NUMBER,
+            self::CHAR          => Token::STRING,
+            self::SPECIAL_CHAR  => Token::OPERATOR,
+            self::LEFT_BRACKET  => Token::LEFT_BRACKET,
+            self::RIGHT_BRACKET => Token::RIGHT_BRACKET,
+            self::SPACE         => Token::NOTHING
+        ),
+    );
+
+    private $accumulator = '';
+
+    private $state = Token::NOTHING;
+
+    private $queue = null;
+
+    public function __construct()
+    {
+        $this->queue = new \SplQueue();
+    }
+
+    /**
+     * Tokenize math expression
+     * @param $expression
+     * @return \SplQueue
+     * @throws \Exception
+     */
+    public function tokenize($expression)
+    {
+        $oldState = null;
+        for ($i=0; $i<strlen($expression); $i++) {
+            $char = substr($expression, $i, 1);
+            $class = $this->getSymbolType($char);
+            $oldState = $this->state;
+            $this->state = $this->transitions[$this->state][$class];
+            if ($this->state == self::ERROR_STATE) {
+                throw new \Exception("Parse expression error at $i column (symbol '$char')");
+            }
+            $this->addToQueue($oldState);
+            $this->accumulator .= $char;
+        }
+        if (!empty($this->accumulator)) {
+            $token = new Token($this->state, $this->accumulator);
+            $this->queue->push($token);
+        }
+
+        return $this->queue;
+    }
+
+    /**
+     * @param $symbol
+     * @return string
+     * @throws \Exception
+     */
+    private function getSymbolType($symbol)
+    {
+        foreach ($this->terms as $class => $regex) {
+            if (preg_match("/$regex/i", $symbol)) {
+                return $class;
+            }
+        }
+
+        throw new \Exception("Unknown char '$symbol'");
+    }
+
+    /**
+     * @param $oldState
+     */
+    private function addToQueue($oldState)
+    {
+        if ($oldState == Token::NOTHING) {
+            $this->accumulator = '';
+
+            return;
+        }
+
+        if (($this->state != $oldState) || ($oldState == Token::LEFT_BRACKET) || ($oldState == Token::RIGHT_BRACKET)) {
+            $token = new Token($oldState, $this->accumulator);
+            $this->queue->push($token);
+            $this->accumulator = '';
+        }
+    }
+}