add column unique numbering scheme, more efficient selects

tests/Unit/ColumnNumeratorTest.php

@@ -0,0 +1,72 @@
+<?php
+
+namespace Tests\Unit;
+
+use App\Tables\ColumnNumerator;
+use Tests\TestCase;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+
+class ColumnNumeratorTest extends TestCase
+{
+    public function testIncrementsWithDefaultInit()
+    {
+        $n = new ColumnNumerator();
+
+        self::assertEquals('a', $n->next());
+        self::assertEquals('b', $n->next());
+        self::assertEquals('c', $n->next());
+    }
+
+    public function testIncrementsWithCustomInit()
+    {
+        $n = new ColumnNumerator('r');
+
+        self::assertEquals('r', $n->next());
+        self::assertEquals('s', $n->next());
+        self::assertEquals('t', $n->next());
+    }
+
+    public function testIncrementsMultiChar()
+    {
+        $n = new ColumnNumerator('aaa');
+
+        self::assertEquals('aaa', $n->next());
+        self::assertEquals('aab', $n->next());
+        self::assertEquals('aac', $n->next());
+    }
+
+    public function testOverflowGrow()
+    {
+        $n = new ColumnNumerator('y');
+
+        self::assertEquals('y', $n->next());
+        self::assertEquals('z', $n->next());
+        self::assertEquals('aa', $n->next());
+        self::assertEquals('ab', $n->next());
+    }
+
+    public function testOverflowNoGrow()
+    {
+        $n = new ColumnNumerator('yy');
+
+        self::assertEquals('yy', $n->next());
+        self::assertEquals('yz', $n->next());
+        self::assertEquals('za', $n->next());
+        self::assertEquals('zb', $n->next());
+    }
+
+    public function testResume()
+    {
+        $n = new ColumnNumerator('yy');
+        self::assertEquals('yy', $n->next());
+        self::assertEquals('yz', $n->next());
+
+        $n2 = new ColumnNumerator($n->getState());
+        unset($n);
+
+        self::assertEquals('za', $n2->next(), 'recreated numerator continues');
+        self::assertEquals('zb', $n2->next());
+
+        self::assertEquals($n2->getState(), 'zc', 'State is next string');
+    }
+}