Merge pull request #167 from box/fix_int_float_value_formatters

Fix CellValueFormatter for numeric values

README.md

@@ -2,7 +2,7 @@
 
 [![Latest Stable Version](https://poser.pugx.org/box/spout/v/stable)](https://packagist.org/packages/box/spout)
 [![Project Status](http://opensource.box.com/badges/active.svg)](http://opensource.box.com/badges)
-[![Build Status](https://travis-ci.org/box/spout.svg?branch=master)](http://travis-ci.org/box/spout)
+[![Build Status](https://travis-ci.org/box/spout.svg?branch=master)](https://travis-ci.org/box/spout)
 [![Code Coverage](https://scrutinizer-ci.com/g/box/spout/badges/coverage.png?b=master)](https://scrutinizer-ci.com/g/box/spout/?branch=master)
 [![Total Downloads](https://poser.pugx.org/box/spout/downloads)](https://packagist.org/packages/box/spout)
 [![License](https://poser.pugx.org/box/spout/license)](https://packagist.org/packages/box/spout)
@@ -18,16 +18,9 @@ Join the community and come discuss about Spout: [![Gitter](https://badges.gitte
 
 Spout can be installed directly from [Composer](https://getcomposer.org/).
 
-Add "box/spout" as a dependency in your project's composer.json file:
-```json
-"require": {
-    "box/spout": "~2.0"
-}
+Run the following command:
 ```
-
-Then run the install command from Composer:
-```
-php composer.phar install
+$ composer require box/spout
 ```
 
 ### Manual installation
@@ -62,8 +55,8 @@ Regardless of the file type, the interface to read a file is always the same:
 use Box\Spout\Reader\ReaderFactory;
 use Box\Spout\Common\Type;
 
-$reader = ReaderFactory::create(Type::CSV); // for CSV files
-//$reader = ReaderFactory::create(Type::XLSX); // for XLSX files
+$reader = ReaderFactory::create(Type::XLSX); // for XLSX files
+//$reader = ReaderFactory::create(Type::CSV); // for CSV files
 //$reader = ReaderFactory::create(Type::ODS); // for ODS files
 
 $reader->open($filePath);
@@ -87,8 +80,8 @@ As with the reader, there is one common interface to write data to a file:
 use Box\Spout\Writer\WriterFactory;
 use Box\Spout\Common\Type;
 
-$writer = WriterFactory::create(Type::CSV); // for CSV files
-//$writer = WriterFactory::create(Type::XLSX); // for XLSX files
+$writer = WriterFactory::create(Type::XLSX); // for XLSX files
+//$writer = WriterFactory::create(Type::CSV); // for CSV files
 //$writer = WriterFactory::create(Type::ODS); // for ODS files
 
 $writer->openToFile($filePath); // write data to a file or to a PHP stream
@@ -105,6 +98,8 @@ For XLSX and ODS files, the number of rows per sheet is limited to 1,048,576. By
 
 ## Advanced usage
 
+If you are looking for  how to perform some common, more advanced tasks with Spout, please take a look at the [Wiki](https://github.com/box/spout/wiki). It contains code snippets, ready to be used.
+
 ### Configuring the CSV reader and writer
 
 It is possible to configure both the CSV reader and writer to specify the field separator as well as the field enclosure:
@@ -282,10 +277,12 @@ If you just want to check that everything is working as expected, executing the
 If you want to run performance tests, you will need to checkout the `perf-tests` branch. Multiple test suites can then be run, depending on the expected output:
 
 * `phpunit` - runs the whole test suite (unit + functional + performance tests)
-* `phpunit --testuite no-perf-tests` - only runs the unit and functional tests
-* `phpunit --testuite perf-tests` - only runs the performance tests
+* `phpunit --exclude-group perf-tests` - only runs the unit and functional tests
+* `phpunit --group perf-tests` - only runs the performance tests
 
-For information, the performance tests take about one hour to run (processing 2 million rows files is not a quick thing).
+For information, the performance tests take about 30 minutes to run (processing 1 million rows files is not a quick thing).
+
+> Performance tests status: [![Build Status](https://travis-ci.org/box/spout.svg?branch=perf-tests)](https://travis-ci.org/box/spout)
 
 
 ## Frequently Asked Questions

composer.json

@@ -29,5 +29,11 @@
         "psr-4": {
             "Box\\Spout\\": "src/Spout"
         }
+    },
+    "extra": {
+        "branch-alias": {
+            "dev-master": "2.5.x-dev"
+        }
     }
+
 }

src/Spout/Reader/CSV/RowIterator.php

@@ -13,6 +13,12 @@ use Box\Spout\Common\Helper\EncodingHelper;
  */
 class RowIterator implements IteratorInterface
 {
+    /**
+     * If no value is given to stream_get_line(), it defaults to 8192 (which may be too low).
+     * Alignement with other functions like fgets() is discussed here: https://bugs.php.net/bug.php?id=48421
+     */
+    const MAX_READ_BYTES_PER_LINE = 32768;
+
     /** @var resource Pointer to the CSV file to read */
     protected $filePointer;
 
@@ -147,7 +153,7 @@ class RowIterator implements IteratorInterface
     {
         // Read until the EOL delimiter or EOF is reached. The delimiter's encoding needs to match the CSV's encoding.
         $encodedEOLDelimiter = $this->getEncodedEOLDelimiter();
-        $encodedLineData = $this->globalFunctionsHelper->stream_get_line($this->filePointer, 0, $encodedEOLDelimiter);
+        $encodedLineData = $this->globalFunctionsHelper->stream_get_line($this->filePointer, self::MAX_READ_BYTES_PER_LINE, $encodedEOLDelimiter);
 
         // If the line could have been read, it can be converted to UTF-8
         $utf8EncodedLineData = ($encodedLineData !== false) ?

src/Spout/Reader/CSV/Sheet.php

@@ -11,7 +11,7 @@ use Box\Spout\Reader\SheetInterface;
  */
 class Sheet implements SheetInterface
 {
-    /** @var RowIterator To iterate over the CSV's rows */
+    /** @var \Box\Spout\Reader\CSV\RowIterator To iterate over the CSV's rows */
     protected $rowIterator;
 
     /**
@@ -28,7 +28,7 @@ class Sheet implements SheetInterface
 
     /**
      * @api
-     * @return RowIterator
+     * @return \Box\Spout\Reader\CSV\RowIterator
      */
     public function getRowIterator()
     {

src/Spout/Reader/CSV/SheetIterator.php

@@ -12,7 +12,7 @@ use Box\Spout\Reader\IteratorInterface;
  */
 class SheetIterator implements IteratorInterface
 {
-    /** @var Sheet The CSV unique "sheet" */
+    /** @var \Box\Spout\Reader\CSV\Sheet The CSV unique "sheet" */
     protected $sheet;
 
     /** @var bool Whether the unique "sheet" has already been read */
@@ -67,7 +67,7 @@ class SheetIterator implements IteratorInterface
      * Return the current element
      * @link http://php.net/manual/en/iterator.current.php
      *
-     * @return Sheet
+     * @return \Box\Spout\Reader\CSV\Sheet
      */
     public function current()
     {

src/Spout/Reader/ODS/Helper/CellValueFormatter.php

@@ -47,7 +47,6 @@ class CellValueFormatter
 
     /**
      * Returns the (unescaped) correctly marshalled, cell value associated to the given XML node.
-     * @TODO Add other types !!
      * @see http://docs.oasis-open.org/office/v1.2/os/OpenDocument-v1.2-os-part1.html#refTable13
      *
      * @param \DOMNode $node
@@ -119,7 +118,8 @@ class CellValueFormatter
     protected function formatFloatCellValue($node)
     {
         $nodeValue = $node->getAttribute(self::XML_ATTRIBUTE_VALUE);
-        $cellValue = is_int($nodeValue) ? intval($nodeValue) : floatval($nodeValue);
+        $nodeIntValue = intval($nodeValue);
+        $cellValue = ($nodeIntValue == $nodeValue) ? $nodeIntValue : floatval($nodeValue);
         return $cellValue;
     }
 

src/Spout/Reader/ODS/Sheet.php

@@ -13,13 +13,13 @@ use Box\Spout\Reader\Wrapper\XMLReader;
  */
 class Sheet implements SheetInterface
 {
-    /** @var RowIterator To iterate over sheet's rows */
+    /** @var \Box\Spout\Reader\ODS\RowIterator To iterate over sheet's rows */
     protected $rowIterator;
 
     /** @var int ID of the sheet */
     protected $id;
 
-    /** @var int Index of the sheet, based on order of creation (zero-based) */
+    /** @var int Index of the sheet, based on order in the workbook (zero-based) */
     protected $index;
 
     /** @var string Name of the sheet */
@@ -27,7 +27,7 @@ class Sheet implements SheetInterface
 
     /**
      * @param XMLReader $xmlReader XML Reader, positioned on the "<table:table>" element
-     * @param int $sheetIndex Index of the sheet, based on order of creation (zero-based)
+     * @param int $sheetIndex Index of the sheet, based on order in the workbook (zero-based)
      * @param string $sheetName Name of the sheet
      */
     public function __construct($xmlReader, $sheetIndex, $sheetName)
@@ -39,7 +39,7 @@ class Sheet implements SheetInterface
 
     /**
      * @api
-     * @return RowIterator
+     * @return \Box\Spout\Reader\ODS\RowIterator
      */
     public function getRowIterator()
     {
@@ -48,7 +48,7 @@ class Sheet implements SheetInterface
 
     /**
      * @api
-     * @return int Index of the sheet, based on order of creation (zero-based)
+     * @return int Index of the sheet, based on order in the workbook (zero-based)
      */
     public function getIndex()
     {

src/Spout/Reader/ODS/SheetIterator.php

@@ -102,7 +102,7 @@ class SheetIterator implements IteratorInterface
      * Return the current element
      * @link http://php.net/manual/en/iterator.current.php
      *
-     * @return Sheet
+     * @return \Box\Spout\Reader\ODS\Sheet
      */
     public function current()
     {

src/Spout/Reader/Wrapper/SimpleXMLElement.php

@@ -151,6 +151,22 @@ class SimpleXMLElement
         return $doesElementExist ? $this->wrapSimpleXMLElement($realElement) : null;
     }
 
+    /**
+     * Returns the immediate children.
+     *
+     * @return array The children
+     */
+    public function children()
+    {
+        $children = [];
+
+        foreach ($this->simpleXMLElement->children() as $child) {
+            $children[] = $this->wrapSimpleXMLElement($child);
+        }
+
+        return $children;
+    }
+
     /**
      * @return string
      */

src/Spout/Reader/XLSX/Helper/CellHelper.php

@@ -12,6 +12,14 @@ use Box\Spout\Common\Exception\InvalidArgumentException;
  */
 class CellHelper
 {
+    // Using ord() is super slow... Using a pre-computed hash table instead.
+    private static $columnLetterToIndexMapping = [
+        'A' => 0, 'B' => 1, 'C' => 2, 'D' => 3, 'E' => 4, 'F' => 5, 'G' => 6,
+        'H' => 7, 'I' => 8, 'J' => 9, 'K' => 10, 'L' => 11, 'M' => 12, 'N' => 13,
+        'O' => 14, 'P' => 15, 'Q' => 16, 'R' => 17, 'S' => 18, 'T' => 19, 'U' => 20,
+        'V' => 21, 'W' => 22, 'X' => 23, 'Y' => 24, 'Z' => 25,
+    ];
+
     /**
      * Fills the missing indexes of an array with a given value.
      * For instance, $dataArray = []; $a[1] = 1; $a[3] = 3;
@@ -50,34 +58,31 @@ class CellHelper
         }
 
         $columnIndex = 0;
-        $capitalAAsciiValue = ord('A');
-        $capitalZAsciiValue = ord('Z');
-        $step = $capitalZAsciiValue - $capitalAAsciiValue + 1;
 
         // Remove row information
-        $column = preg_replace('/\d/', '', $cellIndex);
-        $columnLength = strlen($column);
+        $columnLetters = preg_replace('/\d/', '', $cellIndex);
 
-        /*
-         * This is how the following loop will process the data:
-         * A   => 0
-         * Z   => 25
-         * AA  => 26   : (26^(2-1) * (0+1)) + 0
-         * AB  => 27   : (26^(2-1) * (0+1)) + 1
-         * BC  => 54   : (26^(2-1) * (1+1)) + 2
-         * BCZ => 1455 : (26^(3-1) * (1+1)) + (26^(2-1) * (2+1)) + 25
-         */
-        foreach (str_split($column) as $single_cell_index)
-        {
-            $currentColumnIndex = ord($single_cell_index) - $capitalAAsciiValue;
+        // strlen() is super slow too... Using isset() is way faster and not too unreadable,
+        // since we checked before that there are between 1 and 3 letters.
+        $columnLength = isset($columnLetters[1]) ? (isset($columnLetters[2]) ? 3 : 2) : 1;
 
-            if ($columnLength === 1) {
-                $columnIndex += $currentColumnIndex;
-            } else {
-                $columnIndex += pow($step, ($columnLength - 1)) * ($currentColumnIndex + 1);
-            }
-
-            $columnLength--;
+        // Looping over the different letters of the column is slower than this method.
+        // Also, not using the pow() function because it's slooooow...
+        switch ($columnLength) {
+            case 1:
+                $columnIndex = (self::$columnLetterToIndexMapping[$columnLetters]);
+                break;
+            case 2:
+                $firstLetterIndex = (self::$columnLetterToIndexMapping[$columnLetters[0]] + 1) * 26;
+                $secondLetterIndex = self::$columnLetterToIndexMapping[$columnLetters[1]];
+                $columnIndex = $firstLetterIndex + $secondLetterIndex;
+                break;
+            case 3:
+                $firstLetterIndex = (self::$columnLetterToIndexMapping[$columnLetters[0]] + 1) * 676;
+                $secondLetterIndex = (self::$columnLetterToIndexMapping[$columnLetters[1]] + 1) * 26;
+                $thirdLetterIndex = self::$columnLetterToIndexMapping[$columnLetters[2]];
+                $columnIndex = $firstLetterIndex + $secondLetterIndex + $thirdLetterIndex;
+                break;
         }
 
         return $columnIndex;
@@ -86,12 +91,13 @@ class CellHelper
     /**
      * Returns whether a cell index is valid, in an Excel world.
      * To be valid, the cell index should start with capital letters and be followed by numbers.
+     * There can only be 3 letters, as there can only be 16,384 rows, which is equivalent to 'XFE'.
      *
      * @param string $cellIndex The Excel cell index ('A1', 'BC13', ...)
      * @return bool
      */
     protected static function isValidCellIndex($cellIndex)
     {
-        return (preg_match('/^[A-Z]+\d+$/', $cellIndex) === 1);
+        return (preg_match('/^[A-Z]{1,3}\d+$/', $cellIndex) === 1);
     }
 }

src/Spout/Reader/XLSX/Helper/CellValueFormatter.php

@@ -25,19 +25,34 @@ class CellValueFormatter
 
     /** Definition of XML attributes used to parse data */
     const XML_ATTRIBUTE_TYPE = 't';
+    const XML_ATTRIBUTE_STYLE_ID = 's';
+
+    /** Constants used for date formatting */
+    const NUM_SECONDS_IN_ONE_DAY = 86400;
+
+    /**
+     * February 29th, 1900 is NOT a leap year but Excel thinks it is...
+     * @see https://en.wikipedia.org/wiki/Year_1900_problem#Microsoft_Excel
+     */
+    const ERRONEOUS_EXCEL_LEAP_YEAR_DAY = 60;
 
     /** @var SharedStringsHelper Helper to work with shared strings */
     protected $sharedStringsHelper;
 
+    /** @var StyleHelper Helper to work with styles */
+    protected $styleHelper;
+
     /** @var \Box\Spout\Common\Escaper\XLSX Used to unescape XML data */
     protected $escaper;
 
     /**
      * @param SharedStringsHelper $sharedStringsHelper Helper to work with shared strings
+     * @param StyleHelper $styleHelper Helper to work with styles
      */
-    public function __construct($sharedStringsHelper)
+    public function __construct($sharedStringsHelper, $styleHelper)
     {
         $this->sharedStringsHelper = $sharedStringsHelper;
+        $this->styleHelper = $styleHelper;
 
         /** @noinspection PhpUnnecessaryFullyQualifiedNameInspection */
         $this->escaper = new \Box\Spout\Common\Escaper\XLSX();
@@ -53,6 +68,7 @@ class CellValueFormatter
     {
         // Default cell type is "n"
         $cellType = $node->getAttribute(self::XML_ATTRIBUTE_TYPE) ?: self::CELL_TYPE_NUMERIC;
+        $cellStyleId = intval($node->getAttribute(self::XML_ATTRIBUTE_STYLE_ID));
         $vNodeValue = $this->getVNodeValue($node);
 
         if (($vNodeValue === '') && ($cellType !== self::CELL_TYPE_INLINE_STRING)) {
@@ -69,7 +85,7 @@ class CellValueFormatter
             case self::CELL_TYPE_BOOLEAN:
                 return $this->formatBooleanCellValue($vNodeValue);
             case self::CELL_TYPE_NUMERIC:
-                return $this->formatNumericCellValue($vNodeValue);
+                return $this->formatNumericCellValue($vNodeValue, $cellStyleId);
             case self::CELL_TYPE_DATE:
                 return $this->formatDateCellValue($vNodeValue);
             default:
@@ -138,14 +154,59 @@ class CellValueFormatter
 
     /**
      * Returns the cell Numeric value from string of nodeValue.
+     * The value can also represent a timestamp and a DateTime will be returned.
      *
      * @param string $nodeValue
-     * @return int|float The value associated with the cell
+     * @param int $cellStyleId 0 being the default style
+     * @return int|float|\DateTime|null The value associated with the cell
      */
-    protected function formatNumericCellValue($nodeValue)
+    protected function formatNumericCellValue($nodeValue, $cellStyleId)
     {
-        $cellValue = is_int($nodeValue) ? intval($nodeValue) : floatval($nodeValue);
-        return $cellValue;
+        // Numeric values can represent numbers as well as timestamps.
+        // We need to look at the style of the cell to determine whether it is one or the other.
+        $shouldFormatAsDate = $this->styleHelper->shouldFormatNumericValueAsDate($cellStyleId);
+
+        if ($shouldFormatAsDate) {
+            return $this->formatExcelTimestampValue(floatval($nodeValue));
+        } else {
+            $nodeIntValue = intval($nodeValue);
+            return ($nodeIntValue == $nodeValue) ? $nodeIntValue : floatval($nodeValue);
+        }
+    }
+
+    /**
+     * Returns a cell's PHP Date value, associated to the given timestamp.
+     * NOTE: The timestamp is a float representing the number of days since January 1st, 1900.
+     *
+     * @param float $nodeValue
+     * @return \DateTime|null The value associated with the cell or NULL if invalid date value
+     */
+    protected function formatExcelTimestampValue($nodeValue)
+    {
+        // Fix for the erroneous leap year in Excel
+        if (ceil($nodeValue) > self::ERRONEOUS_EXCEL_LEAP_YEAR_DAY) {
+            --$nodeValue;
+        }
+
+        // The value 1.0 represents 1900-01-01. Numbers below 1.0 are not valid Excel dates.
+        if ($nodeValue < 1.0) {
+            return null;
+        }
+
+        // Do not use any unix timestamps for calculation to prevent
+        // issues with numbers exceeding 2^31.
+        $secondsRemainder = fmod($nodeValue, 1) * self::NUM_SECONDS_IN_ONE_DAY;
+        $secondsRemainder = round($secondsRemainder, 0);
+
+        try {
+            $cellValue = \DateTime::createFromFormat('|Y-m-d', '1899-12-31');
+            $cellValue->modify('+' . intval($nodeValue) . 'days');
+            $cellValue->modify('+' . $secondsRemainder . 'seconds');
+
+            return $cellValue;
+        } catch (\Exception $e) {
+            return null;
+        }
     }
 
     /**

src/Spout/Reader/XLSX/Helper/SharedStringsCaching/FileBasedStrategy.php

@@ -143,7 +143,9 @@ class FileBasedStrategy implements CachingStrategyInterface
         }
 
         $sharedString = null;
-        if (array_key_exists($indexInFile, $this->inMemoryTempFileContents)) {
+
+        // Using isset here because it is way faster than array_key_exists...
+        if (isset($this->inMemoryTempFileContents[$indexInFile])) {
             $escapedSharedString = $this->inMemoryTempFileContents[$indexInFile];
             $sharedString = $this->unescapeLineFeed($escapedSharedString);
         }

src/Spout/Reader/XLSX/Helper/SheetHelper.php

@@ -13,9 +13,6 @@ use Box\Spout\Reader\XLSX\Sheet;
  */
 class SheetHelper
 {
-    /** Extension for XML files */
-    const XML_EXTENSION = '.xml';
-
     /** Paths of XML files relative to the XLSX file root */
     const CONTENT_TYPES_XML_FILE_PATH = '[Content_Types].xml';
     const WORKBOOK_XML_RELS_FILE_PATH = 'xl/_rels/workbook.xml.rels';
@@ -79,9 +76,15 @@ class SheetHelper
             $sheetNode = $sheetNodes[$i];
             $sheetDataXMLFilePath = $sheetNode->getAttribute('PartName');
 
-            $sheets[] = $this->getSheetFromXML($sheetDataXMLFilePath, $i);
+            $sheets[] = $this->getSheetFromXML($sheetDataXMLFilePath);
         }
 
+        // make sure the sheets are sorted by index
+        // (as the sheets are not necessarily in this order in the XML file)
+        usort($sheets, function ($sheet1, $sheet2) {
+            return ($sheet1->getIndex() - $sheet2->getIndex());
+        });
+
         return $sheets;
     }
 
@@ -91,60 +94,37 @@ class SheetHelper
      * Then we look at "xl/worbook.xml" to find the sheet entry associated to the found ID.
      * The entry contains the ID and name of the sheet.
      *
-     * If this piece of data can't be found by parsing the different XML files, the ID will default
-     * to the sheet index, based on order in [Content_Types].xml. Similarly, the sheet's name will
-     * default to the data sheet XML file name ("xl/worksheets/sheet2.xml" => "sheet2").
-     *
      * @param string $sheetDataXMLFilePath Path of the sheet data XML file as in [Content_Types].xml
-     * @param int $sheetIndexZeroBased Index of the sheet, based on order in [Content_Types].xml (zero-based)
      * @return \Box\Spout\Reader\XLSX\Sheet Sheet instance
      */
-    protected function getSheetFromXML($sheetDataXMLFilePath, $sheetIndexZeroBased)
+    protected function getSheetFromXML($sheetDataXMLFilePath)
     {
-        $sheetName = $this->getDefaultSheetName($sheetDataXMLFilePath);
-
-        /*
-         * In [Content_Types].xml, the path is "/xl/worksheets/sheet1.xml"
-         * In workbook.xml.rels, it is only "worksheets/sheet1.xml"
-         */
+        // In [Content_Types].xml, the path is "/xl/worksheets/sheet1.xml"
+        // In workbook.xml.rels, it is only "worksheets/sheet1.xml"
         $sheetDataXMLFilePathInWorkbookXMLRels = ltrim($sheetDataXMLFilePath, '/xl/');
 
         // find the node associated to the given file path
         $workbookXMLResElement = $this->getWorkbookXMLRelsAsXMLElement();
         $relationshipNodes = $workbookXMLResElement->xpath('//ns:Relationship[@Target="' . $sheetDataXMLFilePathInWorkbookXMLRels . '"]');
+        $relationshipNode = $relationshipNodes[0];
 
-        if (count($relationshipNodes) === 1) {
-            $relationshipNode = $relationshipNodes[0];
-            $sheetId = $relationshipNode->getAttribute('Id');
+        $relationshipSheetId = $relationshipNode->getAttribute('Id');
 
-            $workbookXMLElement = $this->getWorkbookXMLAsXMLElement();
-            $sheetNodes = $workbookXMLElement->xpath('//ns:sheet[@r:id="' . $sheetId . '"]');
+        $workbookXMLElement = $this->getWorkbookXMLAsXMLElement();
+        $sheetNodes = $workbookXMLElement->xpath('//ns:sheet[@r:id="' . $relationshipSheetId . '"]');
+        $sheetNode = $sheetNodes[0];
 
-            if (count($sheetNodes) === 1) {
-                $sheetNode = $sheetNodes[0];
-                $escapedSheetName = $sheetNode->getAttribute('name');
+        $escapedSheetName = $sheetNode->getAttribute('name');
+        $sheetIdOneBased = $sheetNode->getAttribute('sheetId');
+        $sheetIndexZeroBased = $sheetIdOneBased - 1;
 
-                /** @noinspection PhpUnnecessaryFullyQualifiedNameInspection */
-                $escaper = new \Box\Spout\Common\Escaper\XLSX();
-                $sheetName = $escaper->unescape($escapedSheetName);
-            }
-        }
+        /** @noinspection PhpUnnecessaryFullyQualifiedNameInspection */
+        $escaper = new \Box\Spout\Common\Escaper\XLSX();
+        $sheetName = $escaper->unescape($escapedSheetName);
 
         return new Sheet($this->filePath, $sheetDataXMLFilePath, $this->sharedStringsHelper, $sheetIndexZeroBased, $sheetName);
     }
 
-    /**
-     * Returns the default name of the sheet whose data is located
-     * at the given path.
-     *
-     * @param string $sheetDataXMLFilePath Path of the sheet data XML file
-     * @return string The default sheet name
-     */
-    protected function getDefaultSheetName($sheetDataXMLFilePath)
-    {
-        return $this->globalFunctionsHelper->basename($sheetDataXMLFilePath, self::XML_EXTENSION);
-    }
-
     /**
      * Returns a representation of the workbook.xml.rels file, ready to be parsed.
      * The returned value is cached.

src/Spout/Reader/XLSX/Helper/StyleHelper.php

@@ -0,0 +1,226 @@
+<?php
+
+namespace Box\Spout\Reader\XLSX\Helper;
+
+use Box\Spout\Reader\Wrapper\SimpleXMLElement;
+use Box\Spout\Reader\Wrapper\XMLReader;
+
+/**
+ * Class StyleHelper
+ * This class provides helper functions related to XLSX styles
+ *
+ * @package Box\Spout\Reader\XLSX\Helper
+ */
+class StyleHelper
+{
+    /** Paths of XML files relative to the XLSX file root */
+    const STYLES_XML_FILE_PATH = 'xl/styles.xml';
+
+    /** Nodes used to find relevant information in the styles XML file */
+    const XML_NODE_NUM_FMTS = 'numFmts';
+    const XML_NODE_NUM_FMT = 'numFmt';
+    const XML_NODE_CELL_XFS = 'cellXfs';
+    const XML_NODE_XF = 'xf';
+
+    /** Attributes used to find relevant information in the styles XML file */
+    const XML_ATTRIBUTE_NUM_FMT_ID = 'numFmtId';
+    const XML_ATTRIBUTE_FORMAT_CODE = 'formatCode';
+    const XML_ATTRIBUTE_APPLY_NUMBER_FORMAT = 'applyNumberFormat';
+
+    /** By convention, default style ID is 0 */
+    const DEFAULT_STYLE_ID = 0;
+
+    /** @var string Path of the XLSX file being read */
+    protected $filePath;
+
+    /** @var array Array containing a mapping NUM_FMT_ID => FORMAT_CODE */
+    protected $customNumberFormats;
+
+    /** @var array Array containing a mapping STYLE_ID => [STYLE_ATTRIBUTES] */
+    protected $stylesAttributes;
+
+    /**
+     * @param string $filePath Path of the XLSX file being read
+     */
+    public function __construct($filePath)
+    {
+        $this->filePath = $filePath;
+    }
+
+    /**
+     * Reads the styles.xml file and extract the relevant information from the file.
+     *
+     * @return void
+     */
+    protected function extractRelevantInfo()
+    {
+        $this->customNumberFormats = [];
+        $this->stylesAttributes = [];
+
+        $stylesXmlFilePath = $this->filePath .'#' . self::STYLES_XML_FILE_PATH;
+        $xmlReader = new XMLReader();
+
+        if ($xmlReader->open('zip://' . $stylesXmlFilePath)) {
+            while ($xmlReader->read()) {
+                if ($xmlReader->isPositionedOnStartingNode(self::XML_NODE_NUM_FMTS)) {
+                    $numFmtsNode = new SimpleXMLElement($xmlReader->readOuterXml());
+                    $this->extractNumberFormats($numFmtsNode);
+
+                } else if ($xmlReader->isPositionedOnStartingNode(self::XML_NODE_CELL_XFS)) {
+                    $cellXfsNode = new SimpleXMLElement($xmlReader->readOuterXml());
+                    $this->extractStyleAttributes($cellXfsNode);
+                }
+            }
+
+            $xmlReader->close();
+        }
+    }
+
+    /**
+     * Extracts number formats from the "numFmt" nodes.
+     * For simplicity, the styles attributes are kept in memory. This is possible thanks
+     * to the reuse of formats. So 1 million cells should not use 1 million formats.
+     *
+     * @param SimpleXMLElement $numFmtsNode The "numFmts" node
+     * @return void
+     */
+    protected function extractNumberFormats($numFmtsNode)
+    {
+        foreach ($numFmtsNode->children() as $numFmtNode) {
+            $numFmtId = intval($numFmtNode->getAttribute(self::XML_ATTRIBUTE_NUM_FMT_ID));
+            $formatCode = $numFmtNode->getAttribute(self::XML_ATTRIBUTE_FORMAT_CODE);
+            $this->customNumberFormats[$numFmtId] = $formatCode;
+        }
+    }
+
+    /**
+     * Extracts style attributes from the "xf" nodes, inside the "cellXfs" section.
+     * For simplicity, the styles attributes are kept in memory. This is possible thanks
+     * to the reuse of styles. So 1 million cells should not use 1 million styles.
+     *
+     * @param SimpleXMLElement $cellXfsNode The "cellXfs" node
+     * @return void
+     */
+    protected function extractStyleAttributes($cellXfsNode)
+    {
+        foreach ($cellXfsNode->children() as $xfNode) {
+            $this->stylesAttributes[] = [
+                self::XML_ATTRIBUTE_NUM_FMT_ID => intval($xfNode->getAttribute(self::XML_ATTRIBUTE_NUM_FMT_ID)),
+                self::XML_ATTRIBUTE_APPLY_NUMBER_FORMAT => !!($xfNode->getAttribute(self::XML_ATTRIBUTE_APPLY_NUMBER_FORMAT)),
+            ];
+        }
+    }
+
+    /**
+     * @return array The custom number formats
+     */
+    protected function getCustomNumberFormats()
+    {
+        if (!isset($this->customNumberFormats)) {
+            $this->extractRelevantInfo();
+        }
+
+        return $this->customNumberFormats;
+    }
+
+    /**
+     * @return array The styles attributes
+     */
+    protected function getStylesAttributes()
+    {
+        if (!isset($this->stylesAttributes)) {
+            $this->extractRelevantInfo();
+        }
+
+        return $this->stylesAttributes;
+    }
+
+    /**
+     * Returns whether the style with the given ID should consider
+     * numeric values as timestamps and format the cell as a date.
+     *
+     * @param int $styleId Zero-based style ID
+     * @return bool Whether the cell with the given cell should display a date instead of a numeric value
+     */
+    public function shouldFormatNumericValueAsDate($styleId)
+    {
+        $stylesAttributes = $this->getStylesAttributes();
+
+        // Default style (0) does not format numeric values as timestamps. Only custom styles do.
+        // Also if the style ID does not exist in the styles.xml file, format as numeric value.
+        // Using isset here because it is way faster than array_key_exists...
+        if ($styleId === self::DEFAULT_STYLE_ID || !isset($stylesAttributes[$styleId])) {
+            return false;
+        }
+
+        $styleAttributes = $stylesAttributes[$styleId];
+
+        $applyNumberFormat = $styleAttributes[self::XML_ATTRIBUTE_APPLY_NUMBER_FORMAT];
+        if (!$applyNumberFormat) {
+            return false;
+        }
+
+        $numFmtId = $styleAttributes[self::XML_ATTRIBUTE_NUM_FMT_ID];
+        return $this->doesNumFmtIdIndicateDate($numFmtId);
+    }
+
+    /**
+     * @param int $numFmtId
+     * @return bool Whether the number format ID indicates that the number is a timestamp
+     */
+    protected function doesNumFmtIdIndicateDate($numFmtId)
+    {
+        return (
+            $this->isNumFmtIdBuiltInDateFormat($numFmtId) ||
+            $this->isNumFmtIdCustomDateFormat($numFmtId)
+        );
+    }
+
+    /**
+     * @param int $numFmtId
+     * @return bool Whether the number format ID indicates that the number is a timestamp
+     */
+    protected function isNumFmtIdBuiltInDateFormat($numFmtId)
+    {
+        $builtInDateFormatIds = [14, 15, 16, 17, 18, 19, 20, 21, 22, 45, 46, 47];
+        return in_array($numFmtId, $builtInDateFormatIds);
+    }
+
+    /**
+     * @param int $numFmtId
+     * @return bool Whether the number format ID indicates that the number is a timestamp
+     */
+    protected function isNumFmtIdCustomDateFormat($numFmtId)
+    {
+        $customNumberFormats = $this->getCustomNumberFormats();
+
+        // Using isset here because it is way faster than array_key_exists...
+        if (!isset($customNumberFormats[$numFmtId])) {
+            return false;
+        }
+
+        $customNumberFormat = $customNumberFormats[$numFmtId];
+
+        // Remove extra formatting (what's between [ ], the brackets should not be preceded by a "\")
+        $pattern = '((?<!\\\)\[.+?(?<!\\\)\])';
+        $customNumberFormat = preg_replace($pattern, '', $customNumberFormat);
+
+        // custom date formats contain specific characters to represent the date:
+        // e - yy - m - d - h - s
+        // and all of their variants (yyyy - mm - dd...)
+        $dateFormatCharacters = ['e', 'yy', 'm', 'd', 'h', 's'];
+
+        $hasFoundDateFormatCharacter = false;
+        foreach ($dateFormatCharacters as $dateFormatCharacter) {
+            // character not preceded by "\"
+            $pattern = '/(?<!\\\)' . $dateFormatCharacter . '/';
+
+            if (preg_match($pattern, $customNumberFormat)) {
+                $hasFoundDateFormatCharacter = true;
+                break;
+            }
+        }
+
+        return $hasFoundDateFormatCharacter;
+    }
+}

src/Spout/Reader/XLSX/RowIterator.php

@@ -8,6 +8,7 @@ use Box\Spout\Reader\IteratorInterface;
 use Box\Spout\Reader\Wrapper\XMLReader;
 use Box\Spout\Reader\XLSX\Helper\CellHelper;
 use Box\Spout\Reader\XLSX\Helper\CellValueFormatter;
+use Box\Spout\Reader\XLSX\Helper\StyleHelper;
 
 /**
  * Class RowIterator
@@ -39,6 +40,9 @@ class RowIterator implements IteratorInterface
     /** @var Helper\CellValueFormatter Helper to format cell values */
     protected $cellValueFormatter;
 
+    /** @var Helper\StyleHelper $styleHelper Helper to work with styles */
+    protected $styleHelper;
+
     /** @var int Number of read rows */
     protected $numReadRows = 0;
 
@@ -62,7 +66,9 @@ class RowIterator implements IteratorInterface
         $this->sheetDataXMLFilePath = $this->normalizeSheetDataXMLFilePath($sheetDataXMLFilePath);
 
         $this->xmlReader = new XMLReader();
-        $this->cellValueFormatter = new CellValueFormatter($sharedStringsHelper);
+
+        $this->styleHelper = new StyleHelper($filePath);
+        $this->cellValueFormatter = new CellValueFormatter($sharedStringsHelper, $this->styleHelper);
     }
 
     /**

src/Spout/Reader/XLSX/Sheet.php

@@ -12,10 +12,10 @@ use Box\Spout\Reader\SheetInterface;
  */
 class Sheet implements SheetInterface
 {
-    /** @var RowIterator To iterate over sheet's rows */
+    /** @var \Box\Spout\Reader\XLSX\RowIterator To iterate over sheet's rows */
     protected $rowIterator;
 
-    /** @var int Index of the sheet, based on order of creation (zero-based) */
+    /** @var int Index of the sheet, based on order in the workbook (zero-based) */
     protected $index;
 
     /** @var string Name of the sheet */
@@ -25,7 +25,7 @@ class Sheet implements SheetInterface
      * @param string $filePath Path of the XLSX file being read
      * @param string $sheetDataXMLFilePath Path of the sheet data XML file as in [Content_Types].xml
      * @param Helper\SharedStringsHelper Helper to work with shared strings
-     * @param int $sheetIndex Index of the sheet, based on order of creation (zero-based)
+     * @param int $sheetIndex Index of the sheet, based on order in the workbook (zero-based)
      * @param string $sheetName Name of the sheet
      */
     public function __construct($filePath, $sheetDataXMLFilePath, $sharedStringsHelper, $sheetIndex, $sheetName)
@@ -37,7 +37,7 @@ class Sheet implements SheetInterface
 
     /**
      * @api
-     * @return RowIterator
+     * @return \Box\Spout\Reader\XLSX\RowIterator
      */
     public function getRowIterator()
     {
@@ -46,7 +46,7 @@ class Sheet implements SheetInterface
 
     /**
      * @api
-     * @return int Index of the sheet, based on order of creation (zero-based)
+     * @return int Index of the sheet, based on order in the workbook (zero-based)
      */
     public function getIndex()
     {

src/Spout/Reader/XLSX/SheetIterator.php

@@ -14,7 +14,7 @@ use Box\Spout\Reader\Exception\NoSheetsFoundException;
  */
 class SheetIterator implements IteratorInterface
 {
-    /** @var Sheet[] The list of sheet present in the file */
+    /** @var \Box\Spout\Reader\XLSX\Sheet[] The list of sheet present in the file */
     protected $sheets;
 
     /** @var int The index of the sheet being read (zero-based) */
@@ -67,7 +67,8 @@ class SheetIterator implements IteratorInterface
      */
     public function next()
     {
-        if (array_key_exists($this->currentSheetIndex, $this->sheets)) {
+        // Using isset here because it is way faster than array_key_exists...
+        if (isset($this->sheets[$this->currentSheetIndex])) {
             $currentSheet = $this->sheets[$this->currentSheetIndex];
             $currentSheet->getRowIterator()->end();
 
@@ -79,7 +80,7 @@ class SheetIterator implements IteratorInterface
      * Return the current element
      * @link http://php.net/manual/en/iterator.current.php
      *
-     * @return Sheet
+     * @return \Box\Spout\Reader\XLSX\Sheet
      */
     public function current()
     {

src/Spout/Writer/Common/Helper/AbstractStyleHelper.php

@@ -56,7 +56,9 @@ abstract class AbstractStyleHelper
     protected function hasStyleAlreadyBeenRegistered($style)
     {
         $serializedStyle = $style->serialize();
-        return array_key_exists($serializedStyle, $this->serializedStyleToStyleIdMappingTable);
+
+        // Using isset here because it is way faster than array_key_exists...
+        return isset($this->serializedStyleToStyleIdMappingTable[$serializedStyle]);
     }
 
     /**

src/Spout/Writer/Common/Helper/CellHelper.php

@@ -10,6 +10,9 @@ namespace Box\Spout\Writer\Common\Helper;
  */
 class CellHelper
 {
+    /** @var array Cache containing the mapping column index => cell index */
+    private static $columnIndexToCellIndexCache = [];
+
     /**
      * Returns the cell index (base 26) associated to the base 10 column index.
      * Excel uses A to Z letters for column indexing, where A is the 1st column,
@@ -21,18 +24,26 @@ class CellHelper
      */
     public static function getCellIndexFromColumnIndex($columnIndex)
     {
-        $cellIndex = '';
-        $capitalAAsciiValue = ord('A');
+        $originalColumnIndex = $columnIndex;
 
-        do {
-            $modulus = $columnIndex % 26;
-            $cellIndex = chr($capitalAAsciiValue + $modulus) . $cellIndex;
+        // Using isset here because it is way faster than array_key_exists...
+        if (!isset(self::$columnIndexToCellIndexCache[$originalColumnIndex])) {
+            $cellIndex = '';
+            $capitalAAsciiValue = ord('A');
 
-            // substracting 1 because it's zero-based
-            $columnIndex = intval($columnIndex / 26) - 1;
-        } while ($columnIndex >= 0);
+            do {
+                $modulus = $columnIndex % 26;
+                $cellIndex = chr($capitalAAsciiValue + $modulus) . $cellIndex;
 
-        return $cellIndex;
+                // substracting 1 because it's zero-based
+                $columnIndex = intval($columnIndex / 26) - 1;
+
+            } while ($columnIndex >= 0);
+
+            self::$columnIndexToCellIndexCache[$originalColumnIndex] = $cellIndex;
+        }
+
+        return self::$columnIndexToCellIndexCache[$originalColumnIndex];
     }
 
     /**

src/Spout/Writer/Common/Helper/ZipHelper.php

@@ -12,52 +12,142 @@ class ZipHelper
 {
     const ZIP_EXTENSION = '.zip';
 
+    /** Controls what to do when trying to add an existing file */
+    const EXISTING_FILES_SKIP = 'skip';
+    const EXISTING_FILES_OVERWRITE = 'overwrite';
+
+    /** @var string Path of the folder where the zip file will be created */
+    protected $tmpFolderPath;
+
+    /** @var \ZipArchive The ZipArchive instance */
+    protected $zip;
+
     /**
-     * Zips the root folder and streams the contents of the zip into the given stream
-     *
-     * @param string $folderPath Path to the folder to be zipped
-     * @param resource $streamPointer Pointer to the stream to copy the zip
-     * @return void
+     * @param string $tmpFolderPath Path of the temp folder where the zip file will be created
      */
-    public function zipFolderAndCopyToStream($folderPath, $streamPointer)
+    public function __construct($tmpFolderPath)
     {
-        $zipFilePath = $this->getZipFilePath($folderPath);
-        $this->zipFolder($folderPath, $zipFilePath);
-        $this->copyZipToStream($zipFilePath, $streamPointer);
+        $this->tmpFolderPath = $tmpFolderPath;
+    }
+
+    /**
+     * Returns the already created ZipArchive instance or
+     * creates one if none exists.
+     *
+     * @return \ZipArchive
+     */
+    protected function createOrGetZip()
+    {
+        if (!isset($this->zip)) {
+            $this->zip = new \ZipArchive();
+            $zipFilePath = $this->getZipFilePath();
+
+            $this->zip->open($zipFilePath, \ZipArchive::CREATE|\ZipArchive::OVERWRITE);
+        }
+
+        return $this->zip;
     }
 
     /**
-     * @param string $folderPathToZip Path to the folder to be zipped
      * @return string Path where the zip file of the given folder will be created
      */
-    public function getZipFilePath($folderPathToZip)
+    public function getZipFilePath()
     {
-        return $folderPathToZip . self::ZIP_EXTENSION;
+        return $this->tmpFolderPath . self::ZIP_EXTENSION;
     }
 
     /**
-     * Zips the given folder
+     * Adds the given file, located under the given root folder to the archive.
+     * The file will be compressed.
      *
-     * @param string $folderPath Path of the folder to be zipped
-     * @param string $destinationPath Path where the zip file will be created
+     * Example of use:
+     *   addFileToArchive('/tmp/xlsx/foo', 'bar/baz.xml');
+     *   => will add the file located at '/tmp/xlsx/foo/bar/baz.xml' in the archive, but only as 'bar/baz.xml'
+     *
+     * @param string $rootFolderPath Path of the root folder that will be ignored in the archive tree.
+     * @param string $localFilePath Path of the file to be added, under the root folder
+     * @param string|void $existingFileMode Controls what to do when trying to add an existing file
      * @return void
      */
-    public function zipFolder($folderPath, $destinationPath)
+    public function addFileToArchive($rootFolderPath, $localFilePath, $existingFileMode = self::EXISTING_FILES_OVERWRITE)
     {
-        $zip = new \ZipArchive();
-        if ($zip->open($destinationPath, \ZipArchive::CREATE)) {
-            $this->addFolderToZip($zip, $folderPath);
-            $zip->close();
+        $this->addFileToArchiveWithCompressionMethod(
+            $rootFolderPath,
+            $localFilePath,
+            $existingFileMode,
+            \ZipArchive::CM_DEFAULT
+        );
+    }
+
+    /**
+     * Adds the given file, located under the given root folder to the archive.
+     * The file will NOT be compressed.
+     *
+     * Example of use:
+     *   addUncompressedFileToArchive('/tmp/xlsx/foo', 'bar/baz.xml');
+     *   => will add the file located at '/tmp/xlsx/foo/bar/baz.xml' in the archive, but only as 'bar/baz.xml'
+     *
+     * @param string $rootFolderPath Path of the root folder that will be ignored in the archive tree.
+     * @param string $localFilePath Path of the file to be added, under the root folder
+     * @param string|void $existingFileMode Controls what to do when trying to add an existing file
+     * @return void
+     */
+    public function addUncompressedFileToArchive($rootFolderPath, $localFilePath, $existingFileMode = self::EXISTING_FILES_OVERWRITE)
+    {
+        $this->addFileToArchiveWithCompressionMethod(
+            $rootFolderPath,
+            $localFilePath,
+            $existingFileMode,
+            \ZipArchive::CM_STORE
+        );
+    }
+
+    /**
+     * Adds the given file, located under the given root folder to the archive.
+     * The file will NOT be compressed.
+     *
+     * Example of use:
+     *   addUncompressedFileToArchive('/tmp/xlsx/foo', 'bar/baz.xml');
+     *   => will add the file located at '/tmp/xlsx/foo/bar/baz.xml' in the archive, but only as 'bar/baz.xml'
+     *
+     * @param string $rootFolderPath Path of the root folder that will be ignored in the archive tree.
+     * @param string $localFilePath Path of the file to be added, under the root folder
+     * @param string $existingFileMode Controls what to do when trying to add an existing file
+     * @param int $compressionMethod The compression method
+     * @return void
+     */
+    protected function addFileToArchiveWithCompressionMethod($rootFolderPath, $localFilePath, $existingFileMode, $compressionMethod)
+    {
+        $zip = $this->createOrGetZip();
+
+        if (!$this->shouldSkipFile($zip, $localFilePath, $existingFileMode)) {
+            $normalizedFullFilePath = $this->getNormalizedRealPath($rootFolderPath . '/' . $localFilePath);
+            $zip->addFile($normalizedFullFilePath, $localFilePath);
+
+            if (self::canChooseCompressionMethod()) {
+                $zip->setCompressionName($localFilePath, $compressionMethod);
+            }
         }
     }
 
     /**
-     * @param \ZipArchive $zip
-     * @param string $folderPath Path of the folder to add to the zip
+     * @return bool Whether it is possible to choose the desired compression method to be used
+     */
+    public static function canChooseCompressionMethod()
+    {
+        // setCompressionName() is a PHP7+ method...
+        return (method_exists(new \ZipArchive(), 'setCompressionName'));
+    }
+
+    /**
+     * @param string $folderPath Path to the folder to be zipped
+     * @param string|void $existingFileMode Controls what to do when trying to add an existing file
      * @return void
      */
-    protected function addFolderToZip($zip, $folderPath)
+    public function addFolderToArchive($folderPath, $existingFileMode = self::EXISTING_FILES_OVERWRITE)
     {
+        $zip = $this->createOrGetZip();
+
         $folderRealPath = $this->getNormalizedRealPath($folderPath) . '/';
         $itemIterator = new \RecursiveIteratorIterator(new \RecursiveDirectoryIterator($folderPath, \RecursiveDirectoryIterator::SKIP_DOTS), \RecursiveIteratorIterator::SELF_FIRST);
 
@@ -65,14 +155,26 @@ class ZipHelper
             $itemRealPath = $this->getNormalizedRealPath($itemInfo->getPathname());
             $itemLocalPath = str_replace($folderRealPath, '', $itemRealPath);
 
-            if ($itemInfo->isFile()) {
+            if ($itemInfo->isFile() && !$this->shouldSkipFile($zip, $itemLocalPath, $existingFileMode)) {
                 $zip->addFile($itemRealPath, $itemLocalPath);
-            } else if ($itemInfo->isDir()) {
-                $zip->addEmptyDir($itemLocalPath);
             }
         }
     }
 
+    /**
+     * @param \ZipArchive $zip
+     * @param string $itemLocalPath
+     * @param string $existingFileMode
+     * @return bool Whether the file should be added to the archive or skipped
+     */
+    protected function shouldSkipFile($zip, $itemLocalPath, $existingFileMode)
+    {
+        // Skip files if:
+        //   - EXISTING_FILES_SKIP mode chosen
+        //   - File already exists in the archive
+        return ($existingFileMode === self::EXISTING_FILES_SKIP && $zip->locateName($itemLocalPath) !== false);
+    }
+
     /**
      * Returns canonicalized absolute pathname, containing only forward slashes.
      *
@@ -85,16 +187,30 @@ class ZipHelper
         return str_replace(DIRECTORY_SEPARATOR, '/', $realPath);
     }
 
+    /**
+     * Closes the archive and copies it into the given stream
+     *
+     * @param resource $streamPointer Pointer to the stream to copy the zip
+     * @return void
+     */
+    public function closeArchiveAndCopyToStream($streamPointer)
+    {
+        $zip = $this->createOrGetZip();
+        $zip->close();
+        unset($this->zip);
+
+        $this->copyZipToStream($streamPointer);
+    }
+
     /**
      * Streams the contents of the zip file into the given stream
      *
-     * @param string $zipFilePath Path to the zip file
      * @param resource $pointer Pointer to the stream to copy the zip
      * @return void
      */
-    protected function copyZipToStream($zipFilePath, $pointer)
+    protected function copyZipToStream($pointer)
     {
-        $zipFilePointer = fopen($zipFilePath, 'r');
+        $zipFilePointer = fopen($this->getZipFilePath(), 'r');
         stream_copy_to_stream($zipFilePointer, $pointer);
         fclose($zipFilePointer);
     }

src/Spout/Writer/Common/Sheet.php

@@ -24,7 +24,7 @@ class Sheet
     /** @var array Associative array [SHEET_INDEX] => [SHEET_NAME] keeping track of sheets' name to enforce uniqueness */
     protected static $SHEETS_NAME_USED = [];
 
-    /** @var int Index of the sheet, based on order of creation (zero-based) */
+    /** @var int Index of the sheet, based on order in the workbook (zero-based) */
     protected $index;
 
     /** @var string Name of the sheet */
@@ -34,7 +34,7 @@ class Sheet
     protected $stringHelper;
 
     /**
-     * @param int $sheetIndex Index of the sheet, based on order of creation (zero-based)
+     * @param int $sheetIndex Index of the sheet, based on order in the workbook (zero-based)
      */
     public function __construct($sheetIndex)
     {
@@ -45,7 +45,7 @@ class Sheet
 
     /**
      * @api
-     * @return int Index of the sheet, based on order of creation (zero-based)
+     * @return int Index of the sheet, based on order in the workbook (zero-based)
      */
     public function getIndex()
     {

src/Spout/Writer/ODS/Helper/FileSystemHelper.php

@@ -103,14 +103,12 @@ class FileSystemHelper extends \Box\Spout\Common\Helper\FileSystemHelper
     protected function createManifestFile()
     {
         $manifestXmlFileContents = <<<EOD
-<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
-<manifest:manifest xmlns:manifest="urn:oasis:names:tc:opendocument:xmlns:manifest:1.0">
+<?xml version="1.0" encoding="UTF-8"?>
+<manifest:manifest xmlns:manifest="urn:oasis:names:tc:opendocument:xmlns:manifest:1.0" manifest:version="1.2">
     <manifest:file-entry manifest:full-path="/" manifest:media-type="application/vnd.oasis.opendocument.spreadsheet"/>
     <manifest:file-entry manifest:full-path="styles.xml" manifest:media-type="text/xml"/>
     <manifest:file-entry manifest:full-path="content.xml" manifest:media-type="text/xml"/>
     <manifest:file-entry manifest:full-path="meta.xml" manifest:media-type="text/xml"/>
-    <manifest:file-entry manifest:full-path="mimetype" manifest:media-type="text/plain"/>
-    <manifest:file-entry manifest:full-path="META-INF/manifest.xml" manifest:media-type="text/xml"/>
 </manifest:manifest>
 EOD;
 
@@ -265,10 +263,17 @@ EOD;
      */
     public function zipRootFolderAndCopyToStream($streamPointer)
     {
-        $zipHelper = new ZipHelper();
-        $zipHelper->zipFolderAndCopyToStream($this->rootFolder, $streamPointer);
+        $zipHelper = new ZipHelper($this->rootFolder);
+
+        // In order to have the file's mime type detected properly, files need to be added
+        // to the zip file in a particular order.
+        // @see http://www.jejik.com/articles/2010/03/how_to_correctly_create_odf_documents_using_zip/
+        $zipHelper->addUncompressedFileToArchive($this->rootFolder, self::MIMETYPE_FILE_NAME);
+
+        $zipHelper->addFolderToArchive($this->rootFolder, ZipHelper::EXISTING_FILES_SKIP);
+        $zipHelper->closeArchiveAndCopyToStream($streamPointer);
 
         // once the zip is copied, remove it
-        $this->deleteFile($zipHelper->getZipFilePath($this->rootFolder));
+        $this->deleteFile($zipHelper->getZipFilePath());
     }
 }

src/Spout/Writer/ODS/Internal/Worksheet.php

@@ -146,7 +146,8 @@ class Worksheet implements WorksheetInterface
         for ($i = 0; $i < $cellsCount; $i++) {
             $currentCellValue = $dataRow[$currentCellIndex];
 
-            if (!array_key_exists($nextCellIndex, $dataRow) || $currentCellValue !== $dataRow[$nextCellIndex]) {
+            // Using isset here because it is way faster than array_key_exists...
+            if (!isset($dataRow[$nextCellIndex]) || $currentCellValue !== $dataRow[$nextCellIndex]) {
                 $numTimesValueRepeated = ($nextCellIndex - $currentCellIndex);
                 $data .= $this->getCellContent($currentCellValue, $styleIndex, $numTimesValueRepeated);
 

src/Spout/Writer/Style/Style.php

@@ -293,7 +293,7 @@ class Style
         if (!$this->hasSetFontSize && $baseStyle->getFontSize() !== self::DEFAULT_FONT_SIZE) {
             $mergedStyle->setFontSize($baseStyle->getFontSize());
         }
-        if (!$this->hasSetFontSize && $baseStyle->getFontColor() !== self::DEFAULT_FONT_COLOR) {
+        if (!$this->hasSetFontColor && $baseStyle->getFontColor() !== self::DEFAULT_FONT_COLOR) {
             $mergedStyle->setFontColor($baseStyle->getFontColor());
         }
         if (!$this->hasSetFontName && $baseStyle->getFontName() !== self::DEFAULT_FONT_NAME) {

src/Spout/Writer/XLSX/Helper/FileSystemHelper.php

@@ -94,7 +94,7 @@ class FileSystemHelper extends \Box\Spout\Common\Helper\FileSystemHelper
      */
     protected function createRootFolder()
     {
-        $this->rootFolder = $this->createFolder($this->baseFolderPath, uniqid('xlsx'));
+        $this->rootFolder = $this->createFolder($this->baseFolderPath, uniqid('xlsx', true));
         return $this;
     }
 
@@ -353,10 +353,19 @@ EOD;
      */
     public function zipRootFolderAndCopyToStream($streamPointer)
     {
-        $zipHelper = new ZipHelper();
-        $zipHelper->zipFolderAndCopyToStream($this->rootFolder, $streamPointer);
+        $zipHelper = new ZipHelper($this->rootFolder);
+
+        // In order to have the file's mime type detected properly, files need to be added
+        // to the zip file in a particular order.
+        // "[Content_Types].xml" then at least 2 files located in "xl" folder should be zipped first.
+        $zipHelper->addFileToArchive($this->rootFolder, self::CONTENT_TYPES_XML_FILE_NAME);
+        $zipHelper->addFileToArchive($this->rootFolder, self::XL_FOLDER_NAME . '/' . self::WORKBOOK_XML_FILE_NAME);
+        $zipHelper->addFileToArchive($this->rootFolder, self::XL_FOLDER_NAME . '/' . self::STYLES_XML_FILE_NAME);
+
+        $zipHelper->addFolderToArchive($this->rootFolder, ZipHelper::EXISTING_FILES_SKIP);
+        $zipHelper->closeArchiveAndCopyToStream($streamPointer);
 
         // once the zip is copied, remove it
-        $this->deleteFile($zipHelper->getZipFilePath($this->rootFolder));
+        $this->deleteFile($zipHelper->getZipFilePath());
     }
 }

src/Spout/Writer/XLSX/Internal/Worksheet.php

@@ -131,36 +131,38 @@ EOD;
         $rowIndex = $this->lastWrittenRowIndex + 1;
         $numCells = count($dataRow);
 
-        $data = '<row r="' . $rowIndex . '" spans="1:' . $numCells . '">';
+        $rowXML = '<row r="' . $rowIndex . '" spans="1:' . $numCells . '">';
 
         foreach($dataRow as $cellValue) {
             $columnIndex = CellHelper::getCellIndexFromColumnIndex($cellNumber);
-            $data .= '<c r="' . $columnIndex . $rowIndex . '"';
-            $data .= ' s="' . $style->getId() . '"';
+            $cellXML = '<c r="' . $columnIndex . $rowIndex . '"';
+            $cellXML .= ' s="' . $style->getId() . '"';
 
             if (CellHelper::isNonEmptyString($cellValue)) {
                 if ($this->shouldUseInlineStrings) {
-                    $data .= ' t="inlineStr"><is><t>' . $this->stringsEscaper->escape($cellValue) . '</t></is></c>';
+                    $cellXML .= ' t="inlineStr"><is><t>' . $this->stringsEscaper->escape($cellValue) . '</t></is></c>';
                 } else {
                     $sharedStringId = $this->sharedStringsHelper->writeString($cellValue);
-                    $data .= ' t="s"><v>' . $sharedStringId . '</v></c>';
+                    $cellXML .= ' t="s"><v>' . $sharedStringId . '</v></c>';
                 }
             } else if (CellHelper::isBoolean($cellValue)) {
-                $data .= ' t="b"><v>' . $cellValue . '</v></c>';
+                $cellXML .= ' t="b"><v>' . $cellValue . '</v></c>';
             } else if (CellHelper::isNumeric($cellValue)) {
-                $data .= '><v>' . $cellValue . '</v></c>';
+                $cellXML .= '><v>' . $cellValue . '</v></c>';
             } else if (empty($cellValue)) {
-                $data .= '/>';
+                // don't write empty cells (not appending to $cellXML is the right behavior!)
+                $cellXML = '';
             } else {
                 throw new InvalidArgumentException('Trying to add a value with an unsupported type: ' . gettype($cellValue));
             }
 
+            $rowXML .= $cellXML;
             $cellNumber++;
         }
 
-        $data .= '</row>';
+        $rowXML .= '</row>';
 
-        $wasWriteSuccessful = fwrite($this->sheetFilePointer, $data);
+        $wasWriteSuccessful = fwrite($this->sheetFilePointer, $rowXML);
         if ($wasWriteSuccessful === false) {
             throw new IOException("Unable to write data in {$this->worksheetFilePath}");
         }

tests/Spout/Reader/XLSX/Helper/CellValueFormatterTest.php

@@ -0,0 +1,126 @@
+<?php
+
+namespace Box\Spout\Reader\XLSX\Helper;
+
+/**
+ * Class CellValueFormatterTest
+ *
+ * @package Box\Spout\Reader\XLSX\Helper
+ */
+class CellValueFormatterTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * @return array
+     */
+    public function dataProviderForTestExcelDate()
+    {
+        return [
+            [CellValueFormatter::CELL_TYPE_NUMERIC, 42429, '2016-02-29 00:00:00'],
+            [CellValueFormatter::CELL_TYPE_NUMERIC, '146098', '2299-12-31 00:00:00'],
+            [CellValueFormatter::CELL_TYPE_NUMERIC, -700, null],
+            [CellValueFormatter::CELL_TYPE_NUMERIC, 0, null],
+            [CellValueFormatter::CELL_TYPE_NUMERIC, 0.5, null],
+            [CellValueFormatter::CELL_TYPE_NUMERIC, 1, '1900-01-01 00:00:00'],
+            [CellValueFormatter::CELL_TYPE_NUMERIC, 59.999988425926, '1900-02-28 23:59:59'],
+            [CellValueFormatter::CELL_TYPE_NUMERIC, 60.458333333333, '1900-02-28 11:00:00'],
+        ];
+    }
+
+    /**
+     * @dataProvider dataProviderForTestExcelDate
+     *
+     * @param string $cellType
+     * @param int|float|string $nodeValue
+     * @param string|null $expectedDateAsString
+     * @return void
+     */
+    public function testExcelDate($cellType, $nodeValue, $expectedDateAsString)
+    {
+        $nodeListMock = $this->getMockBuilder('DOMNodeList')->disableOriginalConstructor()->getMock();
+
+        $nodeListMock
+            ->expects($this->atLeastOnce())
+            ->method('item')
+            ->with(0)
+            ->will($this->returnValue((object)['nodeValue' => $nodeValue]));
+
+        $nodeMock = $this->getMockBuilder('DOMElement')->disableOriginalConstructor()->getMock();
+
+        $nodeMock
+            ->expects($this->atLeastOnce())
+            ->method('getAttribute')
+            ->will($this->returnValueMap([
+                [CellValueFormatter::XML_ATTRIBUTE_TYPE, $cellType],
+                [CellValueFormatter::XML_ATTRIBUTE_STYLE_ID, 123],
+            ]));
+
+        $nodeMock
+            ->expects($this->atLeastOnce())
+            ->method('getElementsByTagName')
+            ->with(CellValueFormatter::XML_NODE_VALUE)
+            ->will($this->returnValue($nodeListMock));
+
+        $styleHelperMock = $this->getMockBuilder('Box\Spout\Reader\XLSX\Helper\StyleHelper')->disableOriginalConstructor()->getMock();
+
+        $styleHelperMock
+            ->expects($this->once())
+            ->method('shouldFormatNumericValueAsDate')
+            ->with(123)
+            ->will($this->returnValue(true));
+
+        $formatter = new CellValueFormatter(null, $styleHelperMock);
+        $result = $formatter->extractAndFormatNodeValue($nodeMock);
+
+        if ($expectedDateAsString === null) {
+            $this->assertNull($result);
+        } else {
+            $this->assertInstanceOf('DateTime', $result);
+            $this->assertSame($expectedDateAsString, $result->format('Y-m-d H:i:s'));
+        }
+    }
+
+    /**
+     * @return array
+     */
+    public function dataProviderForTestFormatNumericCellValueWithNumbers()
+    {
+        return [
+            [42, 42, 'integer'],
+            [42.5, 42.5, 'double'],
+            [-42, -42, 'integer'],
+            [-42.5, -42.5, 'double'],
+            ['42', 42, 'integer'],
+            ['42.5', 42.5, 'double'],
+            [865640023012945, 865640023012945, 'integer'],
+            ['865640023012945', 865640023012945, 'integer'],
+            [865640023012945.5, 865640023012945.5, 'double'],
+            ['865640023012945.5', 865640023012945.5, 'double'],
+            [PHP_INT_MAX, PHP_INT_MAX, 'integer'],
+            [~PHP_INT_MAX + 1, ~PHP_INT_MAX + 1, 'integer'], // ~PHP_INT_MAX === PHP_INT_MIN, PHP_INT_MIN being PHP7+
+            [PHP_INT_MAX + 1, PHP_INT_MAX + 1, 'double'],
+        ];
+    }
+
+    /**
+     * @dataProvider dataProviderForTestFormatNumericCellValueWithNumbers
+     *
+     * @param int|float|string $value
+     * @param int|float $expectedFormattedValue
+     * @param string $expectedType
+     * @return void
+     */
+    public function testFormatNumericCellValueWithNumbers($value, $expectedFormattedValue, $expectedType)
+    {
+        $styleHelperMock = $this->getMockBuilder('Box\Spout\Reader\XLSX\Helper\StyleHelper')->disableOriginalConstructor()->getMock();
+        $styleHelperMock
+            ->expects($this->once())
+            ->method('shouldFormatNumericValueAsDate')
+            ->will($this->returnValue(false));
+
+        $formatter = new CellValueFormatter(null, $styleHelperMock);
+        $formattedValue = \ReflectionHelper::callMethodOnObject($formatter, 'formatNumericCellValue', $value, 0);
+
+        $this->assertEquals($expectedFormattedValue, $formattedValue);
+        $this->assertEquals($expectedType, gettype($formattedValue));
+    }
+}

tests/Spout/Reader/XLSX/Helper/StyleHelperTest.php

@@ -0,0 +1,134 @@
+<?php
+
+namespace Box\Spout\Reader\XLSX\Helper;
+
+/**
+ * Class StyleHelperTest
+ *
+ * @package Box\Spout\Reader\XLSX\Helper
+ */
+class StyleHelperTest extends \PHPUnit_Framework_TestCase
+{
+
+    /**
+     * @param array $styleAttributes
+     * @param array|void $customNumberFormats
+     * @return StyleHelper
+     */
+    private function getStyleHelperMock($styleAttributes, $customNumberFormats = [])
+    {
+        /** @var StyleHelper $styleHelper */
+        $styleHelper = $this->getMockBuilder('\Box\Spout\Reader\XLSX\Helper\StyleHelper')
+                            ->setMethods(['getCustomNumberFormats', 'getStylesAttributes'])
+                            ->disableOriginalConstructor()
+                            ->getMock();
+
+        $styleHelper->method('getStylesAttributes')->willReturn($styleAttributes);
+        $styleHelper->method('getCustomNumberFormats')->willReturn($customNumberFormats);
+
+        return $styleHelper;
+    }
+
+    /**
+     * @return void
+     */
+    public function testShouldFormatNumericValueAsDateWithDefaultStyle()
+    {
+        $styleHelper = $this->getStyleHelperMock([]);
+        $shouldFormatAsDate = $styleHelper->shouldFormatNumericValueAsDate(0);
+        $this->assertFalse($shouldFormatAsDate);
+    }
+
+    /**
+     * @return void
+     */
+    public function testShouldFormatNumericValueAsDateWhenStyleIdNotListed()
+    {
+        $styleHelper = $this->getStyleHelperMock([['applyNumberFormat' => true]]);
+        $shouldFormatAsDate = $styleHelper->shouldFormatNumericValueAsDate(1);
+        $this->assertFalse($shouldFormatAsDate);
+    }
+
+    /**
+     * @return void
+     */
+    public function testShouldFormatNumericValueAsDateWhenShouldNotApplyNumberFormat()
+    {
+        $styleHelper = $this->getStyleHelperMock([[], ['applyNumberFormat' => false]]);
+        $shouldFormatAsDate = $styleHelper->shouldFormatNumericValueAsDate(1);
+        $this->assertFalse($shouldFormatAsDate);
+    }
+
+    /**
+     * @return void
+     */
+    public function testShouldFormatNumericValueAsDateWithBuiltinDateFormats()
+    {
+        $builtinNumFmtIdsForDate = [14, 15, 16, 17, 18, 19, 20, 21, 22, 45, 46, 47];
+
+        foreach ($builtinNumFmtIdsForDate as $builtinNumFmtIdForDate) {
+            $styleHelper = $this->getStyleHelperMock([[], ['applyNumberFormat' => true, 'numFmtId' => $builtinNumFmtIdForDate]]);
+            $shouldFormatAsDate = $styleHelper->shouldFormatNumericValueAsDate(1);
+
+            $this->assertTrue($shouldFormatAsDate);
+        }
+    }
+
+    /**
+     * @return void
+     */
+    public function testShouldFormatNumericValueAsDateWhenCustomNumberFormatNotFound()
+    {
+        $styleHelper = $this->getStyleHelperMock([[], ['applyNumberFormat' => true, 'numFmtId' => 165]], [166 => []]);
+        $shouldFormatAsDate = $styleHelper->shouldFormatNumericValueAsDate(1);
+
+        $this->assertFalse($shouldFormatAsDate);
+    }
+
+    /**
+     * @return array
+     */
+    public function dataProviderForCustomDateFormats()
+    {
+        return [
+            // number format, expectedResult
+            ['[$-409]dddd\,\ mmmm\ d\,\ yy', true],
+            ['[$-409]d\-mmm\-yy;@', true],
+            ['[$-409]d\-mmm\-yyyy;@', true],
+            ['mm/dd/yy;@', true],
+            ['[$-F800]dddd\,\ mmmm\ dd\,\ yyyy', true],
+            ['m/d;@', true],
+            ['m/d/yy;@', true],
+            ['[$-409]d\-mmm;@', true],
+            ['[$-409]dd\-mmm\-yy;@', true],
+            ['[$-409]mmm\-yy;@', true],
+            ['[$-409]mmmm\-yy;@', true],
+            ['[$-409]mmmm\ d\,\ yyyy;@', true],
+            ['[$-409]m/d/yy\ h:mm\ AM/PM;@', true],
+            ['m/d/yy\ h:mm;@', true],
+            ['[$-409]mmmmm;@', true],
+            ['[$-409]mmmmm\-yy;@', true],
+            ['m/d/yyyy;@', true],
+            ['[$-409]m/d/yy\--h:mm;@', true],
+            ['GENERAL', false],
+            ['\ma\yb\e', false],
+            ['[Red]foo;', false],
+        ];
+    }
+
+    /**
+     * @dataProvider dataProviderForCustomDateFormats
+     *
+     * @param string $numberFormat
+     * @param bool $expectedResult
+     * @return void
+     */
+    public function testShouldFormatNumericValueAsDateWithCustomDateFormats($numberFormat, $expectedResult)
+    {
+        $numFmtId = 165;
+        $styleHelper = $this->getStyleHelperMock([[], ['applyNumberFormat' => true, 'numFmtId' => $numFmtId]], [$numFmtId => $numberFormat]);
+        $shouldFormatAsDate = $styleHelper->shouldFormatNumericValueAsDate(1);
+
+        $this->assertEquals($expectedResult, $shouldFormatAsDate);
+    }
+}

tests/Spout/Reader/XLSX/ReaderTest.php

@@ -73,6 +73,28 @@ class ReaderTest extends \PHPUnit_Framework_TestCase
         }
     }
 
+    /**
+     * @return void
+     */
+    public function testReadShouldSupportSheetsDefinitionInRandomOrder()
+    {
+        $allRows = $this->getAllRowsForFile('two_sheets_with_sheets_definition_in_reverse_order.xlsx');
+
+        $expectedRows = [
+            ['s1 - A1', 's1 - B1', 's1 - C1', 's1 - D1', 's1 - E1'],
+            ['s1 - A2', 's1 - B2', 's1 - C2', 's1 - D2', 's1 - E2'],
+            ['s1 - A3', 's1 - B3', 's1 - C3', 's1 - D3', 's1 - E3'],
+            ['s1 - A4', 's1 - B4', 's1 - C4', 's1 - D4', 's1 - E4'],
+            ['s1 - A5', 's1 - B5', 's1 - C5', 's1 - D5', 's1 - E5'],
+            ['s2 - A1', 's2 - B1', 's2 - C1', 's2 - D1', 's2 - E1'],
+            ['s2 - A2', 's2 - B2', 's2 - C2', 's2 - D2', 's2 - E2'],
+            ['s2 - A3', 's2 - B3', 's2 - C3', 's2 - D3', 's2 - E3'],
+            ['s2 - A4', 's2 - B4', 's2 - C4', 's2 - D4', 's2 - E4'],
+            ['s2 - A5', 's2 - B5', 's2 - C5', 's2 - D5', 's2 - E5'],
+        ];
+        $this->assertEquals($expectedRows, $allRows);
+    }
+
     /**
      * @return void
      */
@@ -113,6 +135,52 @@ class ReaderTest extends \PHPUnit_Framework_TestCase
         $this->assertEquals($expectedRows, $allRows);
     }
 
+    /**
+     * @return void
+     */
+    public function testReadShouldSupportNumericTimestampFormattedDifferentlyAsDate()
+    {
+        // make sure dates are always created with the same timezone
+        date_default_timezone_set('UTC');
+
+        $allRows = $this->getAllRowsForFile('sheet_with_same_numeric_value_date_formatted_differently.xlsx');
+
+        $expectedDate = \DateTime::createFromFormat('Y-m-d H:i:s', '2015-01-01 00:00:00');
+        $expectedRows = [
+            array_fill(0, 10, $expectedDate),
+            array_fill(0, 10, $expectedDate),
+            array_fill(0, 10, $expectedDate),
+            array_merge(array_fill(0, 7, $expectedDate), ['', '', '']),
+        ];
+
+        $this->assertEquals($expectedRows, $allRows);
+    }
+
+    /**
+     * @return void
+     */
+    public function testReadShouldSupportDifferentDatesAsNumericTimestamp()
+    {
+        // make sure dates are always created with the same timezone
+        date_default_timezone_set('UTC');
+
+        $allRows = $this->getAllRowsForFile('sheet_with_different_numeric_value_dates.xlsx');
+
+        $expectedRows = [
+            [
+                \DateTime::createFromFormat('Y-m-d H:i:s', '2015-09-01 00:00:00'),
+                \DateTime::createFromFormat('Y-m-d H:i:s', '2015-09-02 00:00:00'),
+                \DateTime::createFromFormat('Y-m-d H:i:s', '2015-09-01 22:23:00'),
+            ],
+            [
+                \DateTime::createFromFormat('Y-m-d H:i:s', '1900-02-28 23:59:59'),
+                \DateTime::createFromFormat('Y-m-d H:i:s', '1900-03-01 00:00:00'),
+                \DateTime::createFromFormat('Y-m-d H:i:s', '1900-02-28 11:00:00'), // 1900-02-29 should be converted to 1900-02-28
+            ]
+        ];
+        $this->assertEquals($expectedRows, $allRows);
+    }
+
     /**
      * @return void
      */

tests/Spout/Writer/ODS/WriterTest.php

@@ -5,6 +5,7 @@ namespace Box\Spout\Writer\ODS;
 use Box\Spout\Common\Type;
 use Box\Spout\Reader\Wrapper\XMLReader;
 use Box\Spout\TestUsingResource;
+use Box\Spout\Writer\Common\Helper\ZipHelper;
 use Box\Spout\Writer\WriterFactory;
 
 /**
@@ -368,6 +369,30 @@ class WriterTest extends \PHPUnit_Framework_TestCase
         $this->assertValueWasWrittenToSheet($fileName, 1, 'a dream');
     }
 
+    /**
+     * @return void
+     */
+    public function testGeneratedFileShouldHaveTheCorrectMimeType()
+    {
+        // Only PHP7+ gives the correct mime type since it requires adding
+        // uncompressed files to the final archive (which support was added in PHP7)
+        if (!ZipHelper::canChooseCompressionMethod()) {
+            $this->markTestSkipped(
+                'The PHP version used does not support setting the compression method of archived files,
+                resulting in the mime type to be detected incorrectly.'
+            );
+        }
+
+        $fileName = 'test_mime_type.ods';
+        $resourcePath = $this->getGeneratedResourcePath($fileName);
+        $dataRow = ['foo'];
+
+        $this->writeToODSFile([$dataRow], $fileName);
+
+        $finfo = new \finfo(FILEINFO_MIME_TYPE);
+        $this->assertEquals('application/vnd.oasis.opendocument.spreadsheet', $finfo->file($resourcePath));
+    }
+
     /**
      * @param array $allRows
      * @param string $fileName

tests/Spout/Writer/XLSX/WriterTest.php

@@ -385,6 +385,21 @@ class WriterTest extends \PHPUnit_Framework_TestCase
         $this->assertInlineDataWasWrittenToSheet($fileName, 1, 'control's _x0015_ "character"');
     }
 
+    /**
+     * @return void
+     */
+    public function testGeneratedFileShouldHaveTheCorrectMimeType()
+    {
+        $fileName = 'test_mime_type.xlsx';
+        $resourcePath = $this->getGeneratedResourcePath($fileName);
+        $dataRows = [['foo']];
+
+        $this->writeToXLSXFile($dataRows, $fileName);
+
+        $finfo = new \finfo(FILEINFO_MIME_TYPE);
+        $this->assertEquals('application/vnd.openxmlformats-officedocument.spreadsheetml.sheet', $finfo->file($resourcePath));
+    }
+
     /**
      * @param array $allRows
      * @param string $fileName