Initial SQLite development (#1)

Reviewed-on: #1

src/Op.php

@@ -0,0 +1,48 @@
+<?php declare(strict_types=1);
+
+namespace BitBadger\PDODocument;
+
+/**
+ * The types of logical operations allowed for JSON fields
+ */
+enum Op
+{
+    /** Equals (=) */
+    case EQ;
+    /** Greater Than (>) */
+    case GT;
+    /** Greater Than or Equal To (>=) */
+    case GE;
+    /** Less Than (<) */
+    case LT;
+    /** Less Than or Equal To (<=) */
+    case LE;
+    /** Not Equal to (<>) */
+    case NE;
+    /** Between (BETWEEN) */
+    case BT;
+    /** Exists (IS NOT NULL) */
+    case EX;
+    /** Does Not Exist (IS NULL) */
+    case NEX;
+
+    /**
+     * Get the string representation of this operator
+     *
+     * @return string The operator to use in SQL statements
+     */
+    public function toString(): string
+    {
+        return match ($this) {
+            Op::EQ  => "=",
+            Op::GT  => ">",
+            Op::GE  => ">=",
+            Op::LT  => "<",
+            Op::LE  => "<=",
+            Op::NE  => "<>",
+            Op::BT  => "BETWEEN",
+            Op::EX  => "IS NOT NULL",
+            Op::NEX => "IS NULL"
+        };
+    }
+}