Cell value objects (#383)

* first stab at cell objects, #182
* removed comment parameter, streamlined cell detection, more tests #182
* shorter constant names, missing isFormula() #182
* first batch of changes #182
* documentation #182

src/Spout/Writer/Common/Cell.php

@@ -0,0 +1,166 @@
+<?php
+
+namespace Box\Spout\Writer\Common;
+
+use Box\Spout\Writer\Common\Helper\CellHelper;
+
+/**
+ * Class Cell
+ *
+ * @package Box\Spout\Writer\Common
+ */
+class Cell
+{
+    /**
+     * Numeric cell type (whole numbers, fractional numbers, dates)
+     */
+    const TYPE_NUMERIC = 0;
+
+    /**
+     * String (text) cell type
+     */
+    const TYPE_STRING = 1;
+
+    /**
+     * Formula cell type
+     * Not used at the moment
+     */
+    const TYPE_FORMULA = 2;
+
+    /**
+     * Empty cell type
+     */
+    const TYPE_EMPTY = 3;
+
+    /**
+     * Boolean cell type
+     */
+    const TYPE_BOOLEAN = 4;
+
+    /**
+     * Error cell type
+     */
+    const TYPE_ERROR = 5;
+
+    /**
+     * The value of this cell
+     * @var mixed|null
+     */
+    protected $value = null;
+
+    /**
+     * The cell type
+     * @var int|null
+     */
+    protected $type = null;
+
+    /**
+     * Cell constructor.
+     * @param $value mixed
+     */
+    public function __construct($value)
+    {
+        $this->setValue($value);
+    }
+
+    /**
+     * @param $value mixed
+     */
+    public function setValue($value)
+    {
+        $this->value = $value;
+        $this->type = $this->detectType($value);
+    }
+
+    /**
+     * @return mixed|null
+     */
+    public function getValue()
+    {
+        return $this->value;
+    }
+
+    /**
+     * @return int|null
+     */
+    public function getType()
+    {
+        return $this->type;
+    }
+
+    /**
+     * Get the current value type
+     * @return int
+     */
+    protected function detectType($value)
+    {
+        if (CellHelper::isBoolean($value)) {
+            return self::TYPE_BOOLEAN;
+        } elseif (CellHelper::isEmpty($value)) {
+            return self::TYPE_EMPTY;
+        } elseif (CellHelper::isNumeric($this->getValue())) {
+            return self::TYPE_NUMERIC;
+        } elseif (CellHelper::isNonEmptyString($value)) {
+            return self::TYPE_STRING;
+        } else {
+            return self::TYPE_ERROR;
+        }
+    }
+
+    /**
+     * @return bool
+     */
+    public function isBoolean()
+    {
+        return $this->type === self::TYPE_BOOLEAN;
+    }
+
+    /**
+     * @return bool
+     */
+    public function isEmpty()
+    {
+        return $this->type === self::TYPE_EMPTY;
+    }
+
+    /**
+     * Not used at the moment
+     * @return bool
+     */
+    public function isFormula()
+    {
+        return $this->type === self::TYPE_FORMULA;
+    }
+
+    /**
+     * @return bool
+     */
+    public function isNumeric()
+    {
+        return $this->type === self::TYPE_NUMERIC;
+    }
+
+    /**
+     * @return bool
+     */
+    public function isString()
+    {
+        return $this->type === self::TYPE_STRING;
+    }
+
+    /**
+     * @return bool
+     */
+    public function isError()
+    {
+        return $this->type === self::TYPE_ERROR;
+    }
+
+    /**
+     * @return string
+     */
+    public function __toString()
+    {
+        return (string)$this->value;
+    }
+}