Added ability to use statements as fields

Author: rkrx

src/Builder/Select.php

@@ -43,8 +43,15 @@ class Select extends Statement {
 	 * @return $this
 	 */
 	public function field($expression, $alias = null) {
-		if(is_object($expression)) {
-			$expression = (string)$expression;
+		if($alias !== null) {
+			$expression = (string) $expression;
+			$expression = trim($expression);
+			$expression = rtrim($expression, ';');
+			$expression = trim($expression);
+			$lines = explode("\n", $expression);
+			$lines = array_map(function ($line) { return "\t\t{$line}"; }, $lines);
+			$expression = join("\n", $lines);
+			$expression = sprintf("(\n%s\n\t)", $expression);
 		}
 		if($alias === null) {
 			$this->fields[] = $expression;

tests/Builder/SelectTest.php

@@ -157,4 +157,22 @@ public function testCount() {
 
 		$this->assertEquals("SELECT\n\tCOUNT(*)\nFROM\n\ttest1 t1\nINNER JOIN\n\ttest2 t2 ON t1.id=t2.id\nWHERE\n\t(t1.id > 10)\n;\n", $query);
 	}
+
+	public function testSubselectAsField() {
+		$query = TestSelect::create()
+		->field('COUNT(*)')
+		->from('t1', 'test1')
+		->joinInner('t2', 'test2', 't1.id=t2.id')
+		->where('t1.id > 10')
+		->asString();
+
+		$query = TestSelect::create()
+		->field($query, 'testfield')
+		->from('t1', 'test1')
+		->joinInner('t2', 'test2', 't1.id=t2.id')
+		->where('t1.id > 10')
+		->asString();
+
+		$this->assertEquals("SELECT\n\tCOUNT(*)\nFROM\n\ttest1 t1\nINNER JOIN\n\ttest2 t2 ON t1.id=t2.id\nWHERE\n\t(t1.id > 10)\n;\n", $query);
+	}
 }