Add HeaderStrategy

Author: chadicus

src/HeaderStrategy.php

@@ -0,0 +1,77 @@
+<?php
+
+namespace SubjectivePHP\Csv;
+
+use SplFileObject;
+
+final class HeaderStrategy implements HeaderStrategyInterface
+{
+    /**
+     * @var callable
+     */
+    private $getHeadersCallable;
+
+    private function __construct(callable $getHeadersCallable)
+    {
+        $this->getHeadersCallable = $getHeadersCallable;
+    }
+
+    /**
+     * Create header strategy which derives the headers from the first line of the file.
+     *
+     * @return HeaderstrategyInterface
+     */
+    public static function derive() : HeaderStrategyInterface
+    {
+        return new self(
+            function (SplFileObject $fileObject) : array {
+                $row = $fileObject->fgetcsv();
+                $fileObject->rewind();
+                return $row;
+            }
+        );
+    }
+
+    /**
+     * Create header strategy which uses the provided headers array.
+     *
+     * @return HeaderstrategyInterface
+     */
+    public static function provide(array $headers) : HeaderStrategyInterface
+    {
+        return new self(
+            function () use ($headers) : array {
+                return $headers;
+            }
+        );
+    }
+
+    /**
+     * Create header strategy which generates a numeric array whose size is the number of columns in the given file.
+     *
+     * @return HeaderstrategyInterface
+     */
+    public static function none() : HeaderStrategyInterface
+    {
+        return new self(
+            function (SplFileObject $fileObject) : array {
+                $firstRow = $fileObject->fgetcsv();
+                $headers = array_keys($firstRow);
+                $fileObject->rewind();
+                return $headers;
+            }
+        );
+    }
+
+    /**
+     * Extracts headers from the given SplFileObject.
+     *
+     * @param SplFileObject $fileObject The delimited file containing the headers.
+     *
+     * @return array
+     */
+    public function getHeaders(SplFileObject $fileObject) : array
+    {
+        return ($this->getHeadersCallable)($fileObject);
+    }
+}

src/HeaderStrategyInterface.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace SubjectivePHP\Csv;
+
+use SplFileObject;
+
+interface HeaderStrategyInterface
+{
+    public function getHeaders(SplFileObject $fileObject) : array;
+}

tests/HeaderStrategyTest.php

@@ -0,0 +1,63 @@
+<?php
+
+namespace SubjectivePHPTest\Csv;
+
+use SplFileObject;
+use SubjectivePHP\Csv\HeaderStrategy;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @coversDefaultClass \SubjectivePHP\Csv\HeaderStrategy
+ * @covers ::getHeaders
+ * @covers ::<private>
+ */
+final class HeaderStrategyTest extends TestCase
+{
+    /**
+     * @test
+     * @covers ::derive
+     */
+    public function derive()
+    {
+        $fileObject = $this->getFileObject('pipe_delimited.txt', '|');
+        $strategy = HeaderStrategy::derive();
+        $this->assertSame(
+            ['id', 'author', 'title', 'genre', 'price', 'publish_date', 'description'],
+            $strategy->getHeaders($fileObject)
+        );
+    }
+
+    /**
+     * @test
+     * @covers ::provide
+     */
+    public function provide()
+    {
+        $headers = ['id', 'author', 'title', 'genre', 'price', 'publish_date', 'description'];
+        $fileObject = $this->getFileObject('basic.csv');
+        $strategy = HeaderStrategy::provide($headers);
+        $this->assertSame($headers, $strategy->getHeaders($fileObject));
+    }
+
+    /**
+     * @test
+     * @covers ::none
+     */
+    public function none()
+    {
+        $fileObject = $this->getFileObject('no_headers.csv');
+        $strategy = HeaderStrategy::none();
+        $this->assertSame(
+            [0, 1, 2, 3, 4, 5, 6],
+            $strategy->getHeaders($fileObject)
+        );
+    }
+
+    public function getFileObject(string $fileName, string $delimiter = ',') : SplFileObject
+    {
+         $fileObject = new SplFileObject(__DIR__ . "/_files/{$fileName}");
+         $fileObject->setFlags(SplFileObject::READ_CSV);
+         $fileObject->setCsvControl($delimiter);
+         return $fileObject;
+    }
+}