Support _xlfn. prefix and add ISFORMULA, MODE.SNGL, STDEV.S, STDEV.P

This change adds support for newer functions that are prefixed
by _xlfn. (#356). The calculation engine has been updated to
recognise these as functions, and drop the _xlfn. part.

It also add a couple of the new functions such as STDEV.S/P,
MODE.SNGL, ISFORMULA.

Fixes #356
Closes #390

Author: Josh-G

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - HTML writer creates a generator meta tag - [#312](https://github.com/PHPOffice/PhpSpreadsheet/issues/312) 
 - Support invalid zoom value in XLSX format - [#350](https://github.com/PHPOffice/PhpSpreadsheet/pull/350)
+- Support for `_xlfn.` prefixed functions and `ISFORMULA`, `MODE.SNGL`, `STDEV.S`, `STDEV.P` - [#390](https://github.com/PHPOffice/PhpSpreadsheet/pull/390)
 
 ### Fixed
 

src/PhpSpreadsheet/Calculation/Calculation.php

@@ -23,7 +23,7 @@ class Calculation
     //    Opening bracket
     const CALCULATION_REGEXP_OPENBRACE = '\(';
     //    Function (allow for the old @ symbol that could be used to prefix a function, but we'll ignore it)
-    const CALCULATION_REGEXP_FUNCTION = '@?([A-Z][A-Z0-9\.]*)[\s]*\(';
+    const CALCULATION_REGEXP_FUNCTION = '@?(?:_xlfn\.)?([A-Z][A-Z0-9\.]*)[\s]*\(';
     //    Cell reference (cell or range of cells, with or without a sheet reference)
     const CALCULATION_REGEXP_CELLREF = '((([^\s,!&%^\/\*\+<>=-]*)|(\'[^\']*\')|(\"[^\"]*\"))!)?\$?([a-z]{1,3})\$?(\d{1,7})';
     //    Named Range of cells
@@ -1082,6 +1082,13 @@ class Calculation
             'functionCall' => [Functions::class, 'isEven'],
             'argumentCount' => '1',
         ],
+        'ISFORMULA' => [
+            'category' => Category::CATEGORY_INFORMATION,
+            'functionCall' => [Functions::class, 'isFormula'],
+            'argumentCount' => '1',
+            'passCellReference' => true,
+            'passByReference' => [true],
+        ],
         'ISLOGICAL' => [
             'category' => Category::CATEGORY_INFORMATION,
             'functionCall' => [Functions::class, 'isLogical'],
@@ -1302,6 +1309,11 @@ class Calculation
             'functionCall' => [Statistical::class, 'MODE'],
             'argumentCount' => '1+',
         ],
+        'MODE.SNGL' => [
+            'category' => Category::CATEGORY_STATISTICAL,
+            'functionCall' => [Statistical::class, 'MODE'],
+            'argumentCount' => '1+',
+        ],
         'MONTH' => [
             'category' => Category::CATEGORY_DATE_AND_TIME,
             'functionCall' => [DateTime::class, 'MONTHOFYEAR'],
@@ -1700,6 +1712,16 @@ class Calculation
             'functionCall' => [Statistical::class, 'STDEV'],
             'argumentCount' => '1+',
         ],
+        'STDEV.S' => [
+            'category' => Category::CATEGORY_STATISTICAL,
+            'functionCall' => [Statistical::class, 'STDEV'],
+            'argumentCount' => '1+',
+        ],
+        'STDEV.P' => [
+            'category' => Category::CATEGORY_STATISTICAL,
+            'functionCall' => [Statistical::class, 'STDEVP'],
+            'argumentCount' => '1+',
+        ],
         'STDEVA' => [
             'category' => Category::CATEGORY_STATISTICAL,
             'functionCall' => [Statistical::class, 'STDEVA'],
@@ -3772,10 +3794,6 @@ private function processTokenStack($tokens, $cellID = null, Cell $pCell = null)
                     $namedRange = $matches[6];
                     $this->debugLog->writeDebugLog('Evaluating Named Range ', $namedRange);
 
-                    if (substr($namedRange, 0, 6) === '_xlfn.') {
-                        return $this->raiseFormulaError("undefined named range / function '$token'");
-                    }
-
                     $cellValue = $this->extractNamedRange($namedRange, ((null !== $pCell) ? $pCellWorksheet : null), false);
                     $pCell->attach($pCellParent);
                     $this->debugLog->writeDebugLog('Evaluation Result for named range ', $namedRange, ' is ', $this->showTypeDetails($cellValue));

src/PhpSpreadsheet/Calculation/Functions.php

@@ -2,6 +2,8 @@
 
 namespace PhpOffice\PhpSpreadsheet\Calculation;
 
+use PhpOffice\PhpSpreadsheet\Cell\Cell;
+
 class Functions
 {
     const PRECISION = 8.88E-016;
@@ -642,4 +644,21 @@ public static function flattenSingleValue($value = '')
 
         return $value;
     }
+
+    /**
+     * ISFORMULA.
+     *
+     * @param mixed $value The cell to check
+     * @param Cell $pCell The current cell (containing this formula)
+     *
+     * @return bool|string
+     */
+    public static function isFormula($value = '', Cell $pCell = null)
+    {
+        if ($pCell === null) {
+            return self::REF();
+        }
+
+        return substr($pCell->getWorksheet()->getCell($value)->getValue(), 0, 1) === '=';
+    }
 }

tests/PhpSpreadsheetTests/Calculation/CalculationTest.php

@@ -102,4 +102,19 @@ public function providerCanLoadAllSupportedLocales()
             ['tr'],
         ];
     }
+
+    public function testDoesHandleXlfnFunctions()
+    {
+        $calculation = Calculation::getInstance();
+
+        $tree = $calculation->parseFormula('=_xlfn.ISFORMULA(A1)');
+        self::assertCount(3, $tree);
+        $function = $tree[2];
+        self::assertEquals('Function', $function['type']);
+
+        $tree = $calculation->parseFormula('=_xlfn.STDEV.S(A1:B2)');
+        self::assertCount(5, $tree);
+        $function = $tree[4];
+        self::assertEquals('Function', $function['type']);
+    }
 }

tests/PhpSpreadsheetTests/Calculation/FunctionsTest.php

@@ -3,6 +3,8 @@
 namespace PhpOffice\PhpSpreadsheetTests\Calculation;
 
 use PhpOffice\PhpSpreadsheet\Calculation\Functions;
+use PhpOffice\PhpSpreadsheet\Cell\Cell;
+use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
 use PHPUnit\Framework\TestCase;
 
 class FunctionsTest extends TestCase
@@ -267,4 +269,42 @@ public function providerN()
     {
         return require 'data/Calculation/Functions/N.php';
     }
+
+    /**
+     * @dataProvider providerIsFormula
+     *
+     * @param mixed $expectedResult
+     * @param mixed $value
+     */
+    public function testIsFormula($expectedResult, $value = 'undefined')
+    {
+        $ourCell = null;
+        if ($value !== 'undefined') {
+            $remoteCell = $this->getMockBuilder(Cell::class)
+                ->disableOriginalConstructor()
+                ->getMock();
+            $remoteCell->method('getValue')
+                ->will($this->returnValue($value));
+
+            $sheet = $this->getMockBuilder(Worksheet::class)
+                ->disableOriginalConstructor()
+                ->getMock();
+            $sheet->method('getCell')
+                ->will($this->returnValue($remoteCell));
+
+            $ourCell = $this->getMockBuilder(Cell::class)
+                ->disableOriginalConstructor()
+                ->getMock();
+            $ourCell->method('getWorksheet')
+                ->will($this->returnValue($sheet));
+        }
+
+        $result = Functions::isFormula($value, $ourCell);
+        self::assertEquals($expectedResult, $result, null, 1E-8);
+    }
+
+    public function providerIsFormula()
+    {
+        return require 'data/Calculation/Functions/ISFORMULA.php';
+    }
 }

tests/data/Calculation/Functions/ISFORMULA.php

@@ -0,0 +1,59 @@
+<?php
+
+return [
+    [
+        false,
+        null,
+    ],
+    [
+        false,
+        -1,
+    ],
+    [
+        false,
+        0,
+    ],
+    [
+        false,
+        1,
+    ],
+    [
+        false,
+        '',
+    ],
+    [
+        false,
+        '2',
+    ],
+    [
+        false,
+        '#VALUE!',
+    ],
+    [
+        false,
+        '#N/A',
+    ],
+    [
+        false,
+        'TRUE',
+    ],
+    [
+        false,
+        true,
+    ],
+    [
+        false,
+        false,
+    ],
+    [
+        true,
+        '="ABC"',
+    ],
+    [
+        true,
+        '=A1',
+    ],
+    [
+        '#REF!',
+    ],
+];