Support for expressions

Author: isublimity

include.php

@@ -20,6 +20,7 @@
 include_once __DIR__ . '/src/Query/WriteToFile.php';
 include_once __DIR__ . '/src/Query/WhereInFile.php';
 include_once __DIR__ . '/src/Query/Query.php';
+include_once __DIR__ . '/src/Query/Expression.php';
 // Transport
 include_once __DIR__ . '/src/Transport/Http.php';
 include_once __DIR__ . '/src/Transport/CurlerRolling.php';

src/Client.php

@@ -463,6 +463,8 @@ public function getCountPendingQueue()
     /**
      * @param mixed[][] $values
      * @param string[]  $columns
+     * @return Statement
+     * @throws Exception\TransportException
      */
     public function insert(string $table, array $values, array $columns = []) : Statement
     {

src/Query/Expression.php

@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ClickHouseDB\Query;
+
+/**
+ * Pass expression "as is" to be sent and executed at server.
+ * P.ex.: `new Expression("UUIDStringToNum('0f372656-6a5b-4727-a4c4-f6357775d926')");`
+ */
+class Expression
+{
+    /** @var string */
+    private $expression;
+
+    public function __construct(string $expression)
+    {
+        $this->expression = $expression;
+    }
+
+    public function __toString() : string
+    {
+        return $this->expression;
+    }
+}

src/Quote/ValueFormatter.php

@@ -5,6 +5,7 @@
 namespace ClickHouseDB\Quote;
 
 use ClickHouseDB\Exception\UnsupportedValueType;
+use ClickHouseDB\Query\Expression;
 use ClickHouseDB\Type\Type;
 use DateTimeInterface;
 use function addslashes;
@@ -36,6 +37,10 @@ public static function formatValue($value, bool $addQuotes = true)
             return $value->getValue();
         }
 
+        if ($value instanceof Expression) {
+            return $value;
+        }
+
         if (is_object($value) && is_callable([$value, '__toString'])) {
             $value = (string) $value;
         }

tests/Query/ExpressionTest.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ClickHouseDB\Tests\Query;
+
+use ClickHouseDB\Query\Expression;
+use ClickHouseDB\Quote\FormatLine;
+use PHPUnit\Framework\TestCase;
+
+final class ExpressionTest extends TestCase
+{
+    public function testToString() : void
+    {
+        $expressionString = "UUIDStringToNum('0f372656-6a5b-4727-a4c4-f6357775d926')";
+        $expressionObject = new Expression($expressionString);
+
+        self::assertEquals(
+            $expressionString,
+            (string) $expressionObject
+        );
+    }
+
+    public function testExpressionValueForInsert() : void
+    {
+        $expressionString = "UUIDStringToNum('0f372656-6a5b-4727-a4c4-f6357775d926')";
+        $preparedValue    = FormatLine::Insert([new Expression($expressionString)]);
+
+        self::assertEquals(
+            $expressionString,
+            $preparedValue
+        );
+    }
+}