SQL operator refactor

* Added few new operators that were left hardcoded
* Changed "Operator" to "Functor"
* Better hierarchy - less mess
* Serialized SQL queries should contain fewer braces

src/Controllers/IndexController.php

@@ -57,10 +57,10 @@ class IndexController
 		$stmt = (new SqlSelectStatement)
 			->setColumn('id')
 			->setTable('post')
-			->setCriterion((new SqlConjunction)
+			->setCriterion((new SqlConjunctionFunctor)
-				->add(new SqlEqualsOperator('type', new SqlBinding(PostType::Image)))
+				->add(new SqlEqualsFunctor('type', new SqlBinding(PostType::Image)))
-				->add(new SqlEqualsOperator('safety', new SqlBinding(PostSafety::Safe))))
+				->add(new SqlEqualsFunctor('safety', new SqlBinding(PostSafety::Safe))))
-			->setOrderBy(new SqlRandomOperator(), SqlSelectStatement::ORDER_DESC);
+			->setOrderBy(new SqlRandomFunctor(), SqlSelectStatement::ORDER_DESC);
 		$featuredPostId = Database::fetchOne($stmt)['id'];
 		if (!$featuredPostId)
 			return null;

src/Models/AbstractCrudModel.php

@@ -24,7 +24,7 @@ abstract class AbstractCrudModel implements IModel
 		$stmt = new SqlSelectStatement();
 		$stmt->setColumn('*');
 		$stmt->setTable(static::getTableName());
-		$stmt->setCriterion(new SqlEqualsOperator('id', new SqlBinding($key)));
+		$stmt->setCriterion(new SqlEqualsFunctor('id', new SqlBinding($key)));
 
 		$row = Database::fetchOne($stmt);
 		if ($row)
@@ -40,7 +40,7 @@ abstract class AbstractCrudModel implements IModel
 		$stmt = new SqlSelectStatement();
 		$stmt->setColumn('*');
 		$stmt->setTable(static::getTableName());
-		$stmt->setCriterion(SqlInOperator::fromArray('id', SqlBinding::fromArray(array_unique($ids))));
+		$stmt->setCriterion(SqlInFunctor::fromArray('id', SqlBinding::fromArray(array_unique($ids))));
 
 		$rows = Database::fetchAll($stmt);
 		if ($rows)
@@ -52,7 +52,7 @@ abstract class AbstractCrudModel implements IModel
 	public static function getCount()
 	{
 		$stmt = new SqlSelectStatement();
-		$stmt->setColumn(new SqlAliasOperator(new SqlCountOperator('1'), 'count'));
+		$stmt->setColumn(new SqlAliasFunctor(new SqlCountFunctor('1'), 'count'));
 		$stmt->setTable(static::getTableName());
 		return Database::fetchOne($stmt)['count'];
 	}

src/Models/CommentModel.php

@@ -27,7 +27,7 @@ class CommentModel extends AbstractCrudModel
 
 			$stmt = new SqlUpdateStatement();
 			$stmt->setTable('comment');
-			$stmt->setCriterion(new SqlEqualsOperator('id', new SqlBinding($comment->id)));
+			$stmt->setCriterion(new SqlEqualsFunctor('id', new SqlBinding($comment->id)));
 
 			foreach ($bindings as $key => $val)
 				$stmt->setColumn($key, new SqlBinding($val));
@@ -42,7 +42,7 @@ class CommentModel extends AbstractCrudModel
 		{
 			$stmt = new SqlDeleteStatement();
 			$stmt->setTable('comment');
-			$stmt->setCriterion(new SqlEqualsOperator('id', new SqlBinding($comment->id)));
+			$stmt->setCriterion(new SqlEqualsFunctor('id', new SqlBinding($comment->id)));
 			Database::exec($stmt);
 		});
 	}
@@ -54,7 +54,7 @@ class CommentModel extends AbstractCrudModel
 		$stmt = new SqlSelectStatement();
 		$stmt->setColumn('comment.*');
 		$stmt->setTable('comment');
-		$stmt->setCriterion(new SqlEqualsOperator('post_id', new SqlBinding($key)));
+		$stmt->setCriterion(new SqlEqualsFunctor('post_id', new SqlBinding($key)));
 
 		$rows = Database::fetchAll($stmt);
 		if ($rows)

src/Models/Entities/PostEntity.php

@@ -54,8 +54,8 @@ class PostEntity extends AbstractEntity
 		$stmt = new SqlSelectStatement();
 		$stmt->setColumn('user.*');
 		$stmt->setTable('user');
-		$stmt->addInnerJoin('favoritee', new SqlEqualsOperator('favoritee.user_id', 'user.id'));
+		$stmt->addInnerJoin('favoritee', new SqlEqualsFunctor('favoritee.user_id', 'user.id'));
-		$stmt->setCriterion(new SqlEqualsOperator('favoritee.post_id', new SqlBinding($this->id)));
+		$stmt->setCriterion(new SqlEqualsFunctor('favoritee.post_id', new SqlBinding($this->id)));
 		$rows = Database::fetchAll($stmt);
 		$favorites = UserModel::convertRows($rows);
 		$this->setCache('favoritee', $favorites);
@@ -73,15 +73,15 @@ class PostEntity extends AbstractEntity
 		$stmt->setColumn('post.*');
 		$stmt->setTable('post');
 		$binding = new SqlBinding($this->id);
-		$stmt->addInnerJoin('crossref', (new SqlDisjunction)
+		$stmt->addInnerJoin('crossref', (new SqlDisjunctionFunctor)
 			->add(
-				(new SqlConjunction)
+				(new SqlConjunctionFunctor)
-					->add(new SqlEqualsOperator('post.id', 'crossref.post2_id'))
+					->add(new SqlEqualsFunctor('post.id', 'crossref.post2_id'))
-					->add(new SqlEqualsOperator('crossref.post_id', $binding)))
+					->add(new SqlEqualsFunctor('crossref.post_id', $binding)))
 			->add(
-				(new SqlConjunction)
+				(new SqlConjunctionFunctor)
-					->add(new SqlEqualsOperator('post.id', 'crossref.post_id'))
+					->add(new SqlEqualsFunctor('post.id', 'crossref.post_id'))
-					->add(new SqlEqualsOperator('crossref.post2_id', $binding))));
+					->add(new SqlEqualsFunctor('crossref.post2_id', $binding))));
 		$rows = Database::fetchAll($stmt);
 		$posts = PostModel::convertRows($rows);
 		$this->setCache('relations', $posts);

src/Models/Entities/TagEntity.php

@@ -6,9 +6,9 @@ class TagEntity extends AbstractEntity
 	public function getPostCount()
 	{
 		$stmt = new SqlSelectStatement();
-		$stmt->setColumn(new SqlAliasOperator(new SqlCountOperator('1'), 'count'));
+		$stmt->setColumn(new SqlAliasFunctor(new SqlCountFunctor('1'), 'count'));
 		$stmt->setTable('post_tag');
-		$stmt->setCriterion(new SqlEqualsOperator('tag_id', new SqlBinding($this->id)));
+		$stmt->setCriterion(new SqlEqualsFunctor('tag_id', new SqlBinding($this->id)));
 		return Database::fetchOne($stmt)['count'];
 	}
 }

src/Models/Entities/UserEntity.php

@@ -112,11 +112,11 @@ class UserEntity extends AbstractEntity
 	public function hasFavorited($post)
 	{
 		$stmt = new SqlSelectStatement();
-		$stmt->setColumn(new SqlAliasOperator(new SqlCountOperator('1'), 'count'));
+		$stmt->setColumn(new SqlAliasFunctor(new SqlCountFunctor('1'), 'count'));
 		$stmt->setTable('favoritee');
-		$stmt->setCriterion((new SqlConjunction)
+		$stmt->setCriterion((new SqlConjunctionFunctor)
-			->add(new SqlEqualsOperator('user_id', new SqlBinding($this->id)))
+			->add(new SqlEqualsFunctor('user_id', new SqlBinding($this->id)))
-			->add(new SqlEqualsOperator('post_id', new SqlBinding($post->id))));
+			->add(new SqlEqualsFunctor('post_id', new SqlBinding($post->id))));
 		return Database::fetchOne($stmt)['count'] == 1;
 	}
 
@@ -125,9 +125,9 @@ class UserEntity extends AbstractEntity
 		$stmt = new SqlSelectStatement();
 		$stmt->setColumn('score');
 		$stmt->setTable('post_score');
-		$stmt->setCriterion((new SqlConjunction)
+		$stmt->setCriterion((new SqlConjunctionFunctor)
-			->add(new SqlEqualsOperator('user_id', new SqlBinding($this->id)))
+			->add(new SqlEqualsFunctor('user_id', new SqlBinding($this->id)))
-			->add(new SqlEqualsOperator('post_id', new SqlBinding($post->id))));
+			->add(new SqlEqualsFunctor('post_id', new SqlBinding($post->id))));
 		$row = Database::fetchOne($stmt);
 		if ($row)
 			return intval($row['score']);
@@ -137,27 +137,27 @@ class UserEntity extends AbstractEntity
 	public function getFavoriteCount()
 	{
 		$stmt = new SqlSelectStatement();
-		$stmt->setColumn(new SqlAliasOperator(new SqlCountOperator('1'), 'count'));
+		$stmt->setColumn(new SqlAliasFunctor(new SqlCountFunctor('1'), 'count'));
 		$stmt->setTable('favoritee');
-		$stmt->setCriterion(new SqlEqualsOperator('user_id', new SqlBinding($this->id)));
+		$stmt->setCriterion(new SqlEqualsFunctor('user_id', new SqlBinding($this->id)));
 		return Database::fetchOne($stmt)['count'];
 	}
 
 	public function getCommentCount()
 	{
 		$stmt = new SqlSelectStatement();
-		$stmt->setColumn(new SqlAliasOperator(new SqlCountOperator('1'), 'count'));
+		$stmt->setColumn(new SqlAliasFunctor(new SqlCountFunctor('1'), 'count'));
 		$stmt->setTable('comment');
-		$stmt->setCriterion(new SqlEqualsOperator('commenter_id', new SqlBinding($this->id)));
+		$stmt->setCriterion(new SqlEqualsFunctor('commenter_id', new SqlBinding($this->id)));
 		return Database::fetchOne($stmt)['count'];
 	}
 
 	public function getPostCount()
 	{
 		$stmt = new SqlSelectStatement();
-		$stmt->setColumn(new SqlAliasOperator(new SqlCountOperator('1'), 'count'));
+		$stmt->setColumn(new SqlAliasFunctor(new SqlCountFunctor('1'), 'count'));
 		$stmt->setTable('post');
-		$stmt->setCriterion(new SqlEqualsOperator('uploader_id', new SqlBinding($this->id)));
+		$stmt->setCriterion(new SqlEqualsFunctor('uploader_id', new SqlBinding($this->id)));
 		return Database::fetchOne($stmt)['count'];
 	}
 }

src/Models/PostModel.php

@@ -54,7 +54,7 @@ class PostModel extends AbstractCrudModel
 			foreach ($bindings as $key => $value)
 				$stmt->setColumn($key, new SqlBinding($value));
 
-			$stmt->setCriterion(new SqlEqualsOperator('id', new SqlBinding($post->id)));
+			$stmt->setCriterion(new SqlEqualsFunctor('id', new SqlBinding($post->id)));
 			Database::exec($stmt);
 
 			//tags
@@ -62,7 +62,7 @@ class PostModel extends AbstractCrudModel
 
 			$stmt = new SqlDeleteStatement();
 			$stmt->setTable('post_tag');
-			$stmt->setCriterion(new SqlEqualsOperator('post_id', new SqlBinding($post->id)));
+			$stmt->setCriterion(new SqlEqualsFunctor('post_id', new SqlBinding($post->id)));
 			Database::exec($stmt);
 
 			foreach ($tags as $postTag)
@@ -80,9 +80,9 @@ class PostModel extends AbstractCrudModel
 			$stmt = new SqlDeleteStatement();
 			$stmt->setTable('crossref');
 			$binding = new SqlBinding($post->id);
-			$stmt->setCriterion((new SqlDisjunction)
+			$stmt->setCriterion((new SqlDisjunctionFunctor)
-				->add(new SqlEqualsOperator('post_id', $binding))
+				->add(new SqlEqualsFunctor('post_id', $binding))
-				->add(new SqlEqualsOperator('post2_id', $binding)));
+				->add(new SqlEqualsFunctor('post2_id', $binding)));
 			Database::exec($stmt);
 
 			foreach ($relations as $relatedPost)
@@ -104,7 +104,7 @@ class PostModel extends AbstractCrudModel
 
 			$stmt = new SqlDeleteStatement();
 			$stmt->setTable('post_score');
-			$stmt->setCriterion(new SqlEqualsOperator('post_id', $binding));
+			$stmt->setCriterion(new SqlEqualsFunctor('post_id', $binding));
 			Database::exec($stmt);
 
 			$stmt->setTable('post_tag');
@@ -117,13 +117,13 @@ class PostModel extends AbstractCrudModel
 			Database::exec($stmt);
 
 			$stmt->setTable('crossref');
-			$stmt->setCriterion((new SqlDisjunction)
+			$stmt->setCriterion((new SqlDisjunctionFunctor)
-				->add(new SqlEqualsOperator('post_id', $binding))
+				->add(new SqlEqualsFunctor('post_id', $binding))
-				->add(new SqlEqualsOperator('post_id', $binding)));
+				->add(new SqlEqualsFunctor('post_id', $binding)));
 			Database::exec($stmt);
 
 			$stmt->setTable('post');
-			$stmt->setCriterion(new SqlEqualsOperator('id', $binding));
+			$stmt->setCriterion(new SqlEqualsFunctor('id', $binding));
 			Database::exec($stmt);
 		});
 	}
@@ -136,7 +136,7 @@ class PostModel extends AbstractCrudModel
 		$stmt = new SqlSelectStatement();
 		$stmt->setColumn('*');
 		$stmt->setTable('post');
-		$stmt->setCriterion(new SqlEqualsOperator('name', new SqlBinding($key)));
+		$stmt->setCriterion(new SqlEqualsFunctor('name', new SqlBinding($key)));
 
 		$row = Database::fetchOne($stmt);
 		if ($row)
@@ -161,7 +161,7 @@ class PostModel extends AbstractCrudModel
 		$stmt = new SqlSelectStatement();
 		$stmt->setColumn('*');
 		$stmt->setTable('post');
-		$stmt->setCriterion(new SqlEqualsOperator('file_hash', new SqlBinding($key)));
+		$stmt->setCriterion(new SqlEqualsFunctor('file_hash', new SqlBinding($key)));
 
 		$row = Database::fetchOne($stmt);
 		if ($row)
@@ -193,7 +193,7 @@ class PostModel extends AbstractCrudModel
 		$stmt->setTable('comment');
 		$stmt->addColumn('comment.*');
 		$stmt->addColumn('post_id');
-		$stmt->setCriterion(SqlInOperator::fromArray('post_id', SqlBinding::fromArray($postIds)));
+		$stmt->setCriterion(SqlInFunctor::fromArray('post_id', SqlBinding::fromArray($postIds)));
 		$rows = Database::fetchAll($stmt);
 
 		foreach ($rows as $row)
@@ -234,8 +234,8 @@ class PostModel extends AbstractCrudModel
 		$stmt->setTable('tag');
 		$stmt->addColumn('tag.*');
 		$stmt->addColumn('post_id');
-		$stmt->addInnerJoin('post_tag', new SqlEqualsOperator('post_tag.tag_id', 'tag.id'));
+		$stmt->addInnerJoin('post_tag', new SqlEqualsFunctor('post_tag.tag_id', 'tag.id'));
-		$stmt->setCriterion(SqlInOperator::fromArray('post_id', SqlBinding::fromArray($postIds)));
+		$stmt->setCriterion(SqlInFunctor::fromArray('post_id', SqlBinding::fromArray($postIds)));
 		$rows = Database::fetchAll($stmt);
 
 		foreach ($rows as $row)

src/Models/PropertyModel.php

@@ -44,13 +44,13 @@ class PropertyModel implements IModel
 			$stmt = new SqlSelectStatement();
 			$stmt->setColumn('id');
 			$stmt->setTable('property');
-			$stmt->setCriterion(new SqlEqualsOperator('prop_id', new SqlBinding($propertyId)));
+			$stmt->setCriterion(new SqlEqualsFunctor('prop_id', new SqlBinding($propertyId)));
 			$row = Database::fetchOne($stmt);
 
 			if ($row)
 			{
 				$stmt = new SqlUpdateStatement();
-				$stmt->setCriterion(new SqlEqualsOperator('prop_id', new SqlBinding($propertyId)));
+				$stmt->setCriterion(new SqlEqualsFunctor('prop_id', new SqlBinding($propertyId)));
 			}
 			else
 			{

src/Models/SearchParsers/CommentSearchParser.php

@@ -3,13 +3,13 @@ class CommentSearchParser extends AbstractSearchParser
 {
 	protected function processSetup(&$tokens)
 	{
-		$this->statement->addInnerJoin('post', new SqlEqualsOperator('post_id', 'post.id'));
+		$this->statement->addInnerJoin('post', new SqlEqualsFunctor('post_id', 'post.id'));
 
 		$allowedSafety = PrivilegesHelper::getAllowedSafety();
-		$this->statement->setCriterion(new SqlConjunction());
+		$this->statement->setCriterion(new SqlConjunctionFunctor());
-		$this->statement->getCriterion()->add(SqlInOperator::fromArray('post.safety', SqlBinding::fromArray($allowedSafety)));
+		$this->statement->getCriterion()->add(SqlInFunctor::fromArray('post.safety', SqlBinding::fromArray($allowedSafety)));
 		if (!PrivilegesHelper::confirm(Privilege::ListPosts, 'hidden'))
-			$this->statement->getCriterion()->add(new SqlNegationOperator(new SqlStringExpression('hidden')));
+			$this->statement->getCriterion()->add(new SqlNegationFunctor(new SqlStringExpression('hidden')));
 
 		$this->statement->addOrderBy('comment.id', SqlSelectStatement::ORDER_DESC);
 	}

src/Models/SearchParsers/PostSearchParser.php

@@ -8,10 +8,10 @@ class PostSearchParser extends AbstractSearchParser
 		$config = \Chibi\Registry::getConfig();
 
 		$this->tags = [];
-		$this->statement->setCriterion(new SqlConjunction());
+		$this->statement->setCriterion(new SqlConjunctionFunctor());
 
 		$allowedSafety = PrivilegesHelper::getAllowedSafety();
-		$this->statement->getCriterion()->add(SqlInOperator::fromArray('safety', SqlBinding::fromArray($allowedSafety)));
+		$this->statement->getCriterion()->add(SqlInFunctor::fromArray('safety', SqlBinding::fromArray($allowedSafety)));
 
 		if (\Chibi\Registry::getContext()->user->hasEnabledHidingDislikedPosts() and !in_array('special:disliked', array_map('strtolower', $tokens)))
 			$this->processComplexToken('special', 'disliked', true);
@@ -31,12 +31,12 @@ class PostSearchParser extends AbstractSearchParser
 			$tag = TagModel::findByName($tagName);
 			$innerStmt = new SqlSelectStatement();
 			$innerStmt->setTable('post_tag');
-			$innerStmt->setCriterion((new SqlConjunction)
+			$innerStmt->setCriterion((new SqlConjunctionFunctor)
-				->add(new SqlEqualsOperator('post_tag.post_id', 'post.id'))
+				->add(new SqlEqualsFunctor('post_tag.post_id', 'post.id'))
-				->add(new SqlEqualsOperator('post_tag.tag_id', new SqlBinding($tag->id))));
+				->add(new SqlEqualsFunctor('post_tag.tag_id', new SqlBinding($tag->id))));
-			$operator = new SqlExistsOperator($innerStmt);
+			$operator = new SqlExistsFunctor($innerStmt);
 			if ($neg)
-				$operator = new SqlNegationOperator($operator);
+				$operator = new SqlNegationFunctor($operator);
 			$this->statement->getCriterion()->add($operator);
 		}
 
@@ -58,7 +58,7 @@ class PostSearchParser extends AbstractSearchParser
 		{
 			$ids = preg_split('/[;,]/', $value);
 			$ids = array_map('intval', $ids);
-			return SqlInOperator::fromArray('post.id', SqlBinding::fromArray($ids));
+			return SqlInFunctor::fromArray('post.id', SqlBinding::fromArray($ids));
 		}
 
 		elseif (in_array($key, ['fav', 'favs']))
@@ -66,10 +66,10 @@ class PostSearchParser extends AbstractSearchParser
 			$user = UserModel::findByNameOrEmail($value);
 			$innerStmt = (new SqlSelectStatement)
 				->setTable('favoritee')
-				->setCriterion((new SqlConjunction)
+				->setCriterion((new SqlConjunctionFunctor)
-					->add(new SqlEqualsOperator('favoritee.post_id', 'post.id'))
+					->add(new SqlEqualsFunctor('favoritee.post_id', 'post.id'))
-					->add(new SqlEqualsOperator('favoritee.user_id', new SqlBinding($user->id))));
+					->add(new SqlEqualsFunctor('favoritee.user_id', new SqlBinding($user->id))));
-			return new SqlExistsOperator($innerStmt);
+			return new SqlExistsFunctor($innerStmt);
 		}
 
 		elseif (in_array($key, ['comment', 'commenter']))
@@ -77,66 +77,66 @@ class PostSearchParser extends AbstractSearchParser
 			$user = UserModel::findByNameOrEmail($value);
 			$innerStmt = (new SqlSelectStatement)
 				->setTable('comment')
-				->setCriterion((new SqlConjunction)
+				->setCriterion((new SqlConjunctionFunctor)
-					->add(new SqlEqualsOperator('comment.post_id', 'post.id'))
+					->add(new SqlEqualsFunctor('comment.post_id', 'post.id'))
-					->add(new SqlEqualsOperator('comment.commenter_id', new SqlBinding($user->id))));
+					->add(new SqlEqualsFunctor('comment.commenter_id', new SqlBinding($user->id))));
-			return new SqlExistsOperator($innerStmt);
+			return new SqlExistsFunctor($innerStmt);
 		}
 
 		elseif (in_array($key, ['submit', 'upload', 'uploader', 'uploaded']))
 		{
 			$user = UserModel::findByNameOrEmail($value);
-			return new SqlEqualsOperator('uploader_id', new SqlBinding($user->id));
+			return new SqlEqualsFunctor('uploader_id', new SqlBinding($user->id));
 		}
 
 		elseif (in_array($key, ['idmin', 'id_min']))
-			return new SqlEqualsOrGreaterOperator('post.id', new SqlBinding(intval($value)));
+			return new SqlEqualsOrGreaterFunctor('post.id', new SqlBinding(intval($value)));
 
 		elseif (in_array($key, ['idmax', 'id_max']))
-			return new SqlEqualsOrLesserOperator('post.id', new SqlBinding(intval($value)));
+			return new SqlEqualsOrLesserFunctor('post.id', new SqlBinding(intval($value)));
 
 		elseif (in_array($key, ['scoremin', 'score_min']))
-			return new SqlEqualsOrGreaterOperator('score', new SqlBinding(intval($value)));
+			return new SqlEqualsOrGreaterFunctor('score', new SqlBinding(intval($value)));
 
 		elseif (in_array($key, ['scoremax', 'score_max']))
-			return new SqlEqualsOrLesserOperator('score', new SqlBinding(intval($value)));
+			return new SqlEqualsOrLesserFunctor('score', new SqlBinding(intval($value)));
 
 		elseif (in_array($key, ['tagmin', 'tag_min']))
-			return new SqlEqualsOrGreaterOperator('tag_count', new SqlBinding(intval($value)));
+			return new SqlEqualsOrGreaterFunctor('tag_count', new SqlBinding(intval($value)));
 
 		elseif (in_array($key, ['tagmax', 'tag_max']))
-			return new SqlEqualsOrLesserOperator('tag_count', new SqlBinding(intval($value)));
+			return new SqlEqualsOrLesserFunctor('tag_count', new SqlBinding(intval($value)));
 
 		elseif (in_array($key, ['favmin', 'fav_min']))
-			return new SqlEqualsOrGreaterOperator('fav_count', new SqlBinding(intval($value)));
+			return new SqlEqualsOrGreaterFunctor('fav_count', new SqlBinding(intval($value)));
 
 		elseif (in_array($key, ['favmax', 'fav_max']))
-			return new SqlEqualsOrLesserOperator('fav_count', new SqlBinding(intval($value)));
+			return new SqlEqualsOrLesserFunctor('fav_count', new SqlBinding(intval($value)));
 
 		elseif (in_array($key, ['commentmin', 'comment_min']))
-			return new SqlEqualsOrGreaterOperator('comment_count', new SqlBinding(intval($value)));
+			return new SqlEqualsOrGreaterFunctor('comment_count', new SqlBinding(intval($value)));
 
 		elseif (in_array($key, ['commentmax', 'comment_max']))
-			return new SqlEqualsOrLesserOperator('comment_count', new SqlBinding(intval($value)));
+			return new SqlEqualsOrLesserFunctor('comment_count', new SqlBinding(intval($value)));
 
 		elseif (in_array($key, ['date']))
 		{
 			list ($dateMin, $dateMax) = self::parseDate($value);
-			return (new SqlConjunction)
+			return (new SqlConjunctionFunctor)
-				->add(new SqlEqualsOrLesserOperator('upload_date', new SqlBinding($dateMax)))
+				->add(new SqlEqualsOrLesserFunctor('upload_date', new SqlBinding($dateMax)))
-				->add(new SqlEqualsOrGreaterOperator('upload_date', new SqlBinding($dateMin)));
+				->add(new SqlEqualsOrGreaterFunctor('upload_date', new SqlBinding($dateMin)));
 		}
 
 		elseif (in_array($key, ['datemin', 'date_min']))
 		{
 			list ($dateMin, $dateMax) = self::parseDate($value);
-			return new SqlEqualsOrGreaterOperator('upload_date', new SqlBinding($dateMin));
+			return new SqlEqualsOrGreaterFunctor('upload_date', new SqlBinding($dateMin));
 		}
 
 		elseif (in_array($key, ['datemax', 'date_max']))
 		{
 			list ($dateMin, $dateMax) = self::parseDate($value);
-			return new SqlEqualsOrLesserOperator('upload_date', new SqlBinding($dateMax));
+			return new SqlEqualsOrLesserFunctor('upload_date', new SqlBinding($dateMax));
 		}
 
 		elseif ($key == 'special')
@@ -147,22 +147,22 @@ class PostSearchParser extends AbstractSearchParser
 			{
 				if (!$this->statement->isTableJoined('post_score'))
 				{
-					$this->statement->addLeftOuterJoin('post_score', (new SqlConjunction)
+					$this->statement->addLeftOuterJoin('post_score', (new SqlConjunctionFunctor)
-						->add(new SqlEqualsOperator('post_score.post_id', 'post.id'))
+						->add(new SqlEqualsFunctor('post_score.post_id', 'post.id'))
-						->add(new SqlEqualsOperator('post_score.user_id', new SqlBinding($context->user->id))));
+						->add(new SqlEqualsFunctor('post_score.user_id', new SqlBinding($context->user->id))));
 				}
-				return new SqlEqualsOperator(new SqlIfNullOperator('post_score.score', '0'), '1');
+				return new SqlEqualsFunctor(new SqlIfNullFunctor('post_score.score', '0'), '1');
 			}
 
 			elseif (in_array($value, ['disliked', 'dislikes']))
 			{
 				if (!$this->statement->isTableJoined('post_score'))
 				{
-					$this->statement->addLeftOuterJoin('post_score', (new SqlConjunction)
+					$this->statement->addLeftOuterJoin('post_score', (new SqlConjunctionFunctor)
-						->add(new SqlEqualsOperator('post_score.post_id', 'post.id'))
+						->add(new SqlEqualsFunctor('post_score.post_id', 'post.id'))
-						->add(new SqlEqualsOperator('post_score.user_id', new SqlBinding($context->user->id))));
+						->add(new SqlEqualsFunctor('post_score.user_id', new SqlBinding($context->user->id))));
 				}
-				return new SqlEqualsOperator(new SqlIfNullOperator('post_score.score', '0'), '-1');
+				return new SqlEqualsFunctor(new SqlIfNullFunctor('post_score.score', '0'), '-1');
 			}
 
 			elseif ($value == 'hidden')
@@ -184,7 +184,7 @@ class PostSearchParser extends AbstractSearchParser
 			else
 				throw new SimpleException('Invalid post type: ' . $value);
 
-			return new SqlEqualsOperator('type', new SqlBinding($type));
+			return new SqlEqualsFunctor('type', new SqlBinding($type));
 		}
 
 		return null;
@@ -197,7 +197,7 @@ class PostSearchParser extends AbstractSearchParser
 			return false;
 
 		if ($neg)
-			$criterion = new SqlNegationOperator($criterion);
+			$criterion = new SqlNegationFunctor($criterion);
 
 		$this->statement->getCriterion()->add($criterion);
 		return true;
@@ -239,7 +239,9 @@ class PostSearchParser extends AbstractSearchParser
 			if (!isset($_SESSION['browsing-seed']))
 				$_SESSION['browsing-seed'] = mt_rand();
 			$seed = $_SESSION['browsing-seed'];
-			$orderColumn = 'SUBSTR(post.id * ' . $seed .', LENGTH(post.id) + 2)';
+			$orderColumn = new SqlSubstrFunctor(
+				new SqlMultiplicationFunctor('post.id', $seed),
+				new SqlAdditionFunctor(new SqlLengthFunctor('post.id'), '2'));
 		}
 
 		else

src/Models/SearchParsers/TagSearchParser.php

@@ -5,9 +5,9 @@ class TagSearchParser extends AbstractSearchParser
 	{
 		$allowedSafety = PrivilegesHelper::getAllowedSafety();
 		$this->statement
-			->addInnerJoin('post_tag', new SqlEqualsOperator('tag.id', 'post_tag.tag_id'))
+			->addInnerJoin('post_tag', new SqlEqualsFunctor('tag.id', 'post_tag.tag_id'))
-			->addInnerJoin('post', new SqlEqualsOperator('post.id', 'post_tag.post_id'))
+			->addInnerJoin('post', new SqlEqualsFunctor('post.id', 'post_tag.post_id'))
-			->setCriterion((new SqlConjunction)->add(SqlInOperator::fromArray('safety', SqlBinding::fromArray($allowedSafety))))
+			->setCriterion((new SqlConjunctionFunctor)->add(SqlInFunctor::fromArray('safety', SqlBinding::fromArray($allowedSafety))))
 			->setGroupBy('tag.id');
 	}
 
@@ -20,7 +20,7 @@ class TagSearchParser extends AbstractSearchParser
 			$value = '%' . $value;
 		$value .= '%';
 
-		$this->statement->getCriterion()->add(new SqlNoCaseOperator(new SqlLikeOperator('tag.name', new SqlBinding($value))));
+		$this->statement->getCriterion()->add(new SqlNoCaseFunctor(new SqlLikeFunctor('tag.name', new SqlBinding($value))));
 		return true;
 	}
 

src/Models/SearchParsers/UserSearchParser.php

@@ -8,9 +8,9 @@ class UserSearchParser extends AbstractSearchParser
 
 		if ($value == 'pending')
 		{
-			$this->statement->setCriterion((new SqlDisjunction)
+			$this->statement->setCriterion((new SqlDisjunctionFunctor)
-				->add(new SqlIsNullOperator('staff_confirmed'))
+				->add(new SqlIsFunctor('staff_confirmed', new SqlNullFunctor()))
-				->add(new SqlEqualsOperator('staff_confirmed', '0')));
+				->add(new SqlEqualsFunctor('staff_confirmed', '0')));
 			return true;
 		}
 		return false;
@@ -19,7 +19,7 @@ class UserSearchParser extends AbstractSearchParser
 	protected function processOrderToken($orderByString, $orderDir)
 	{
 		if ($orderByString == 'alpha')
-			$this->statement->setOrderBy(new SqlNoCaseOperator('name'), $orderDir);
+			$this->statement->setOrderBy(new SqlNoCaseFunctor('name'), $orderDir);
 		elseif ($orderByString == 'date')
 			$this->statement->setOrderBy('join_date', $orderDir);
 		else

src/Models/SearchServices/AbstractSearchService.php

@@ -68,7 +68,7 @@ abstract class AbstractSearchService
 		$innerStmt->resetOrderBy();
 
 		$stmt = new SqlSelectStatement();
-		$stmt->setColumn(new SqlAliasOperator(new SqlCountOperator('1'), 'count'));
+		$stmt->setColumn(new SqlAliasFunctor(new SqlCountFunctor('1'), 'count'));
 		$stmt->setSource($innerStmt);
 
 		return Database::fetchOne($stmt)['count'];

src/Models/SearchServices/PostSearchService.php

@@ -24,7 +24,7 @@ class PostSearchService extends AbstractSearchService
 			$stmt = new SqlSelectStatement();
 			$stmt->setTable('post_search');
 			$stmt->setColumn('id');
-			$stmt->setCriterion(new SqlEqualsOperator('post_id', new SqlBinding($postId)));
+			$stmt->setCriterion(new SqlEqualsFunctor('post_id', new SqlBinding($postId)));
 			$rowId = Database::fetchOne($stmt)['id'];
 
 			//it's possible that given post won't show in search results:
@@ -35,10 +35,10 @@ class PostSearchService extends AbstractSearchService
 			$rowId = intval($rowId);
 			$stmt->setColumn('post_id');
 
-			$stmt->setCriterion(new SqlEqualsOperator('id', new SqlBinding($rowId - 1)));
+			$stmt->setCriterion(new SqlEqualsFunctor('id', new SqlBinding($rowId - 1)));
 			$nextPostId = Database::fetchOne($stmt)['post_id'];
 
-			$stmt->setCriterion(new SqlEqualsOperator('id', new SqlBinding($rowId + 1)));
+			$stmt->setCriterion(new SqlEqualsFunctor('id', new SqlBinding($rowId + 1)));
 			$prevPostId = Database::fetchOne($stmt)['post_id'];
 
 			return [$prevPostId, $nextPostId];

src/Models/SearchServices/TagSearchService.php

@@ -3,6 +3,6 @@ class TagSearchService extends AbstractSearchService
 {
 	public static function decorateCustom(SqlSelectStatement $stmt)
 	{
-		$stmt->addColumn(new SqlAliasOperator(new SqlCountOperator('post_tag.post_id'), 'post_count'));
+		$stmt->addColumn(new SqlAliasFunctor(new SqlCountFunctor('post_tag.post_id'), 'post_count'));
 	}
 }

src/Models/TagModel.php

@@ -15,7 +15,7 @@ class TagModel extends AbstractCrudModel
 			$stmt = new SqlUpdateStatement();
 			$stmt->setTable('tag');
 			$stmt->setColumn('name', new SqlBinding($tag->name));
-			$stmt->setCriterion(new SqlEqualsOperator('id', new SqlBinding($tag->id)));
+			$stmt->setCriterion(new SqlEqualsFunctor('id', new SqlBinding($tag->id)));
 
 			Database::exec($stmt);
 		});
@@ -28,12 +28,12 @@ class TagModel extends AbstractCrudModel
 
 		$stmt = new SqlDeleteStatement();
 		$stmt->setTable('post_tag');
-		$stmt->setCriterion(new SqlEqualsOperator('tag_id', $binding));
+		$stmt->setCriterion(new SqlEqualsFunctor('tag_id', $binding));
 		Database::exec($stmt);
 
 		$stmt = new SqlDeleteStatement();
 		$stmt->setTable('tag');
-		$stmt->setCriterion(new SqlEqualsOperator('id', $binding));
+		$stmt->setCriterion(new SqlEqualsFunctor('id', $binding));
 		Database::exec($stmt);
 	}
 
@@ -66,24 +66,24 @@ class TagModel extends AbstractCrudModel
 			$stmt->setColumn('post.id');
 			$stmt->setTable('post');
 			$stmt->setCriterion(
-				(new SqlConjunction)
+				(new SqlConjunctionFunctor)
 				->add(
-					new SqlExistsOperator(
+					new SqlExistsFunctor(
 						(new SqlSelectStatement)
 							->setTable('post_tag')
 							->setCriterion(
-								(new SqlConjunction)
+								(new SqlConjunctionFunctor)
-									->add(new SqlEqualsOperator('post_tag.post_id', 'post.id'))
+									->add(new SqlEqualsFunctor('post_tag.post_id', 'post.id'))
-									->add(new SqlEqualsOperator('post_tag.tag_id', new SqlBinding($sourceTag->id))))))
+									->add(new SqlEqualsFunctor('post_tag.tag_id', new SqlBinding($sourceTag->id))))))
 				->add(
-					new SqlNegationOperator(
+					new SqlNegationFunctor(
-					new SqlExistsOperator(
+					new SqlExistsFunctor(
 						(new SqlSelectStatement)
 							->setTable('post_tag')
 							->setCriterion(
-								(new SqlConjunction)
+								(new SqlConjunctionFunctor)
-									->add(new SqlEqualsOperator('post_tag.post_id', 'post.id'))
+									->add(new SqlEqualsFunctor('post_tag.post_id', 'post.id'))
-									->add(new SqlEqualsOperator('post_tag.tag_id', new SqlBinding($targetTag->id))))))));
+									->add(new SqlEqualsFunctor('post_tag.tag_id', new SqlBinding($targetTag->id))))))));
 			$rows = Database::fetchAll($stmt);
 			$postIds = array_map(function($row) { return $row['id']; }, $rows);
 
@@ -106,8 +106,8 @@ class TagModel extends AbstractCrudModel
 		$stmt = new SqlSelectStatement();
 		$stmt->setColumn('tag.*');
 		$stmt->setTable('tag');
-		$stmt->addInnerJoin('post_tag', new SqlEqualsOperator('post_tag.tag_id', 'tag.id'));
+		$stmt->addInnerJoin('post_tag', new SqlEqualsFunctor('post_tag.tag_id', 'tag.id'));
-		$stmt->setCriterion(new SqlEqualsOperator('post_tag.post_id', new SqlBinding($key)));
+		$stmt->setCriterion(new SqlEqualsFunctor('post_tag.post_id', new SqlBinding($key)));
 
 		$rows = Database::fetchAll($stmt);
 		if ($rows)
@@ -120,7 +120,7 @@ class TagModel extends AbstractCrudModel
 		$stmt = new SqlSelectStatement();
 		$stmt->setColumn('tag.*');
 		$stmt->setTable('tag');
-		$stmt->setCriterion(new SqlNoCaseOperator(new SqlEqualsOperator('name', new SqlBinding($key))));
+		$stmt->setCriterion(new SqlNoCaseFunctor(new SqlEqualsFunctor('name', new SqlBinding($key))));
 
 		$row = Database::fetchOne($stmt);
 		if ($row)
@@ -138,11 +138,11 @@ class TagModel extends AbstractCrudModel
 		$stmt = (new SqlDeleteStatement)
 			->setTable('tag')
 			->setCriterion(
-				new SqlNegationOperator(
+				new SqlNegationFunctor(
-					new SqlExistsOperator(
+					new SqlExistsFunctor(
 						(new SqlSelectStatement)
 							->setTable('post_tag')
-							->setCriterion(new SqlEqualsOperator('post_tag.tag_id', 'tag.id')))));
+							->setCriterion(new SqlEqualsFunctor('post_tag.tag_id', 'tag.id')))));
 		Database::exec($stmt);
 	}
 

src/Models/TokenModel.php

@@ -22,7 +22,7 @@ implements IModel
 
 			$stmt = new SqlUpdateStatement();
 			$stmt->setTable('user_token');
-			$stmt->setCriterion(new SqlEqualsOperator('id', new SqlBinding($token->id)));
+			$stmt->setCriterion(new SqlEqualsFunctor('id', new SqlBinding($token->id)));
 
 			foreach ($bindings as $key => $val)
 				$stmt->setColumn($key, new SqlBinding($val));
@@ -42,7 +42,7 @@ implements IModel
 		$stmt = new SqlSelectStatement();
 		$stmt->setTable('user_token');
 		$stmt->setColumn('*');
-		$stmt->setCriterion(new SqlEqualsOperator('token', new SqlBinding($key)));
+		$stmt->setCriterion(new SqlEqualsFunctor('token', new SqlBinding($key)));
 
 		$row = Database::fetchOne($stmt);
 		if ($row)

src/Models/UserModel.php

@@ -42,7 +42,7 @@ class UserModel extends AbstractCrudModel
 
 			$stmt = (new SqlUpdateStatement)
 				->setTable('user')
-				->setCriterion(new SqlEqualsOperator('id', new SqlBinding($user->id)));
+				->setCriterion(new SqlEqualsFunctor('id', new SqlBinding($user->id)));
 
 			foreach ($bindings as $key => $val)
 				$stmt->setColumn($key, new SqlBinding($val));
@@ -59,26 +59,26 @@ class UserModel extends AbstractCrudModel
 
 			$stmt = new SqlDeleteStatement();
 			$stmt->setTable('post_score');
-			$stmt->setCriterion(new SqlEqualsOperator('user_id', $binding));
+			$stmt->setCriterion(new SqlEqualsFunctor('user_id', $binding));
 			Database::exec($stmt);
 
 			$stmt->setTable('favoritee');
 			Database::exec($stmt);
 
 			$stmt->setTable('user');
-			$stmt->setCriterion(new SqlEqualsOperator('id', $binding));
+			$stmt->setCriterion(new SqlEqualsFunctor('id', $binding));
 			Database::exec($stmt);
 
 			$stmt = new SqlUpdateStatement();
 			$stmt->setTable('comment');
-			$stmt->setCriterion(new SqlEqualsOperator('commenter_id', $binding));
+			$stmt->setCriterion(new SqlEqualsFunctor('commenter_id', $binding));
-			$stmt->setColumn('commenter_id', new SqlNullOperator());
+			$stmt->setColumn('commenter_id', new SqlNullFunctor());
 			Database::exec($stmt);
 
 			$stmt = new SqlUpdateStatement();
 			$stmt->setTable('post');
-			$stmt->setCriterion(new SqlEqualsOperator('uploader_id', $binding));
+			$stmt->setCriterion(new SqlEqualsFunctor('uploader_id', $binding));
-			$stmt->setColumn('uploader_id', new SqlNullOperator());
+			$stmt->setColumn('uploader_id', new SqlNullFunctor());
 			Database::exec($stmt);
 		});
 	}
@@ -90,7 +90,7 @@ class UserModel extends AbstractCrudModel
 		$stmt = new SqlSelectStatement();
 		$stmt->setColumn('*');
 		$stmt->setTable('user');
-		$stmt->setCriterion(new SqlNoCaseOperator(new SqlEqualsOperator('name', new SqlBinding(trim($key)))));
+		$stmt->setCriterion(new SqlNoCaseFunctor(new SqlEqualsFunctor('name', new SqlBinding(trim($key)))));
 
 		$row = Database::fetchOne($stmt);
 		if ($row)
@@ -106,9 +106,9 @@ class UserModel extends AbstractCrudModel
 		$stmt = new SqlSelectStatement();
 		$stmt->setColumn('*');
 		$stmt->setTable('user');
-		$stmt->setCriterion((new SqlDisjunction)
+		$stmt->setCriterion((new SqlDisjunctionFunctor)
-			->add(new SqlNoCaseOperator(new SqlEqualsOperator('name', new SqlBinding(trim($key)))))
+			->add(new SqlNoCaseFunctor(new SqlEqualsFunctor('name', new SqlBinding(trim($key)))))
-			->add(new SqlNoCaseOperator(new SqlEqualsOperator('email_confirmed', new SqlBinding(trim($key))))));
+			->add(new SqlNoCaseFunctor(new SqlEqualsFunctor('email_confirmed', new SqlBinding(trim($key))))));
 
 		$row = Database::fetchOne($stmt);
 		if ($row)
@@ -127,9 +127,9 @@ class UserModel extends AbstractCrudModel
 		{
 			$stmt = new SqlDeleteStatement();
 			$stmt->setTable('post_score');
-			$stmt->setCriterion((new SqlConjunction)
+			$stmt->setCriterion((new SqlConjunctionFunctor)
-				->add(new SqlEqualsOperator('post_id', new SqlBinding($post->id)))
+				->add(new SqlEqualsFunctor('post_id', new SqlBinding($post->id)))
-				->add(new SqlEqualsOperator('user_id', new SqlBinding($user->id))));
+				->add(new SqlEqualsFunctor('user_id', new SqlBinding($user->id))));
 			Database::exec($stmt);
 			$score = intval($score);
 			if ($score != 0)
@@ -163,9 +163,9 @@ class UserModel extends AbstractCrudModel
 		{
 			$stmt = new SqlDeleteStatement();
 			$stmt->setTable('favoritee');
-			$stmt->setCriterion((new SqlConjunction)
+			$stmt->setCriterion((new SqlConjunctionFunctor)
-				->add(new SqlEqualsOperator('post_id', new SqlBinding($post->id)))
+				->add(new SqlEqualsFunctor('post_id', new SqlBinding($post->id)))
-				->add(new SqlEqualsOperator('user_id', new SqlBinding($user->id))));
+				->add(new SqlEqualsFunctor('user_id', new SqlBinding($user->id))));
 			Database::exec($stmt);
 		});
 	}

src/Sql/Functors/BinaryOperatorFunctors/SqlAdditionFunctor.php

@@ -0,0 +1,8 @@
+<?php
+class SqlAdditionFunctor extends SqlBinaryOperatorFunctor
+{
+	protected function getOperator()
+	{
+		return '+';
+	}
+}

src/Sql/Functors/BinaryOperatorFunctors/SqlAliasFunctor.php

@@ -0,0 +1,15 @@
+<?php
+class SqlAliasFunctor extends SqlBinaryOperatorFunctor
+{
+	protected function getOperator()
+	{
+		return 'AS';
+	}
+
+	public function getAsString()
+	{
+		return self::surroundBraces($this->subjects[0])
+			. ' ' . $this->getOperator()
+			. ' ' . $this->subjects[1]->getAsString();
+	}
+}

src/Sql/Functors/BinaryOperatorFunctors/SqlDivisionFunctor.php

@@ -0,0 +1,8 @@
+<?php
+class SqlAdditionFunctor extends SqlBinaryOperatorFunctor
+{
+	protected function getOperator()
+	{
+		return '/';
+	}
+}

src/Sql/Functors/BinaryOperatorFunctors/SqlEqualsFunctor.php

@@ -0,0 +1,8 @@
+<?php
+class SqlEqualsFunctor extends SqlBinaryOperatorFunctor
+{
+	protected function getOperator()
+	{
+		return '=';
+	}
+}

src/Sql/Functors/BinaryOperatorFunctors/SqlEqualsOrGreaterFunctor.php

@@ -0,0 +1,8 @@
+<?php
+class SqlEqualsOrGreaterFunctor extends SqlBinaryOperatorFunctor
+{
+	protected function getOperator()
+	{
+		return '>=';
+	}
+}

src/Sql/Functors/BinaryOperatorFunctors/SqlEqualsOrLesserFunctor.php

@@ -0,0 +1,8 @@
+<?php
+class SqlEqualsOrLesserFunctor extends SqlBinaryOperatorFunctor
+{
+	protected function getOperator()
+	{
+		return '<=';
+	}
+}

src/Sql/Functors/BinaryOperatorFunctors/SqlGreaterFunctor.php

@@ -0,0 +1,8 @@
+<?php
+class SqlGreaterFunctor extends SqlBinaryOperatorFunctor
+{
+	protected function getOperator()
+	{
+		return '>';
+	}
+}

src/Sql/Functors/BinaryOperatorFunctors/SqlIsFunctor.php

@@ -0,0 +1,8 @@
+<?php
+class SqlIsFunctor extends SqlBinaryOperatorFunctor
+{
+	protected function getOperator()
+	{
+		return 'IS';
+	}
+}

src/Sql/Functors/BinaryOperatorFunctors/SqlLesserFunctor.php

@@ -0,0 +1,8 @@
+<?php
+class SqlLesserFunctor extends SqlBinaryOperatorFunctor
+{
+	protected function getOperator()
+	{
+		return '<';
+	}
+}

src/Sql/Functors/BinaryOperatorFunctors/SqlLikeFunctor.php

@@ -0,0 +1,8 @@
+<?php
+class SqlLikeFunctor extends SqlBinaryFunctor
+{
+	protected function getOperator()
+	{
+		return 'LIKE';
+	}
+}

src/Sql/Functors/BinaryOperatorFunctors/SqlMultiplicationFunctor.php

@@ -0,0 +1,8 @@
+<?php
+class SqlMultiplicationFunctor extends SqlBinaryOperatorFunctor
+{
+	protected function getOperator()
+	{
+		return '*';
+	}
+}

src/Sql/Functors/BinaryOperatorFunctors/SqlSubtractionFunctor.php

@@ -0,0 +1,8 @@
+<?php
+class SqlSubtractionFunctor extends SqlBinaryOperatorFunctor
+{
+	protected function getOperator()
+	{
+		return '-';
+	}
+}

src/Sql/Functors/FunctionFunctors/SqlAbsFunctor.php

@@ -0,0 +1,13 @@
+<?php
+class SqlAbsFunctor extends SqlUnaryFunctor
+{
+	public function getFunctionName()
+	{
+		return 'ABS';
+	}
+
+	public function getArgumentCount()
+	{
+		return 1;
+	}
+}

src/Sql/Functors/FunctionFunctors/SqlCountFunctor.php

@@ -0,0 +1,13 @@
+<?php
+class SqlCountFunctor extends SqlFunctionFunctor
+{
+	public function getFunctionName()
+	{
+		return 'COUNT';
+	}
+
+	public function getArgumentCount()
+	{
+		return 1;
+	}
+}

src/Sql/Functors/FunctionFunctors/SqlExistsFunctor.php

@@ -0,0 +1,13 @@
+<?php
+class SqlExistsFunctor extends SqlUnaryFunctor
+{
+	public function getFunctionName()
+	{
+		return 'EXISTS';
+	}
+
+	public function getArgumentCount()
+	{
+		return 1;
+	}
+}

src/Sql/Functors/FunctionFunctors/SqlIfNullFunctor.php

@@ -0,0 +1,13 @@
+<?php
+class SqlIfNullFunctor extends SqlFunctionFunctor
+{
+	public function getFunctionName()
+	{
+		return 'IFNULL';
+	}
+
+	public function getArgumentCount()
+	{
+		return 2;
+	}
+}

src/Sql/Functors/FunctionFunctors/SqlLengthFunctor.php

@@ -0,0 +1,13 @@
+<?php
+class SqlLengthFunctor extends SqlFunctionFunctor
+{
+	public function getFunctionName()
+	{
+		return 'LENGTH';
+	}
+
+	public function getArgumentCount()
+	{
+		return 1;
+	}
+}

src/Sql/Functors/FunctionFunctors/SqlMaxFunctor.php

@@ -0,0 +1,13 @@
+<?php
+class SqlMaxFunctor extends SqlUnaryFunctor
+{
+	public function getFunctionName()
+	{
+		return 'MAX';
+	}
+
+	public function getArgumentCount()
+	{
+		return 1;
+	}
+}

src/Sql/Functors/FunctionFunctors/SqlNegationFunctor.php

@@ -0,0 +1,13 @@
+<?php
+class SqlNegationFunctor extends SqlFunctionFunctor
+{
+	public function getFunctionName()
+	{
+		return 'NOT';
+	}
+
+	public function getArgumentCount()
+	{
+		return 1;
+	}
+}

src/Sql/Functors/FunctionFunctors/SqlNoCaseFunctor.php

@@ -0,0 +1,18 @@
+<?php
+class SqlNoCaseFunctor extends SqlFunctionFunctor
+{
+	public function getFunctionName()
+	{
+		throw new Exception('Not implemented');
+	}
+
+	public function getArgumentCount()
+	{
+		return 1;
+	}
+
+	public function getAsString()
+	{
+		return $this->subjects[0]->getAsString() . ' COLLATE NOCASE';
+	}
+}

src/Sql/Functors/FunctionFunctors/SqlRandomFunctor.php

@@ -0,0 +1,16 @@
+<?php
+class SqlRandomFunctor extends SqlFunctionFunctor
+{
+	public function getFunctionName()
+	{
+		$config = \Chibi\Registry::getConfig();
+		return $config->main->dbDriver == 'sqlite'
+			? 'RANDOM'
+			: 'RAND';
+	}
+
+	public function getArgumentCount()
+	{
+		return 2;
+	}
+}

src/Sql/Functors/FunctionFunctors/SqlSubstrFunctor.php

@@ -0,0 +1,13 @@
+<?php
+class SqlSubstrFunctor extends SqlFunctionFunctor
+{
+	public function getFunctionName()
+	{
+		return 'SUBSTR';
+	}
+
+	public function getArgumentCount()
+	{
+		return [2, 3];
+	}
+}

src/Sql/Functors/MiscOperators/SqlConjunctionFunctor.php

@@ -1,5 +1,5 @@
 <?php
-class SqlConjunction extends SqlVariableOperator
+class SqlConjunctionFunctor extends SqlVariableFunctor
 {
 	public function getAsStringEmpty()
 	{
@@ -10,7 +10,7 @@ class SqlConjunction extends SqlVariableOperator
 	{
 		return '(' . join(' AND ', array_map(function($subject)
 		{
-			return $subject->getAsString();
+			return self::surroundBraces($subject);
 		}, $this->subjects)) . ')';
 	}
 }

src/Sql/Functors/MiscOperators/SqlDisjunctionFunctor.php

@@ -1,5 +1,5 @@
 <?php
-class SqlDisjunction extends SqlVariableOperator
+class SqlDisjunctionFunctor extends SqlVariableFunctor
 {
 	public function getAsStringEmpty()
 	{
@@ -10,7 +10,7 @@ class SqlDisjunction extends SqlVariableOperator
 	{
 		return '(' . join(' OR ', array_map(function($subject)
 		{
-			return $subject->getAsString();
+			return self::surroundBraces($subject);
 		}, $this->subjects)) . ')';
 	}
 }

src/Sql/Functors/MiscOperators/SqlInFunctor.php

@@ -1,5 +1,5 @@
 <?php
-class SqlInOperator extends SqlVariableOperator
+class SqlInFunctor extends SqlVariableFunctor
 {
 	protected $subject;
 
@@ -15,9 +15,9 @@ class SqlInOperator extends SqlVariableOperator
 
 	public function getAsStringNonEmpty()
 	{
-		return '(' . $this->subject->getAsString() . ') IN (' . join(', ', array_map(function($subject)
+		return self::surroundBraces($this->subject) . ' IN (' . join(', ', array_map(function($subject)
 		{
-			return $subject->getAsString();
+			return self::surroundBraces($subject);
 		}, $this->subjects)) . ')';
 	}
 }

src/Sql/Functors/MiscOperators/SqlNullFunctor.php

@@ -1,5 +1,5 @@
 <?php
-class SqlNullOperator extends SqlNullaryOperator
+class SqlNullFunctor extends SqlFunctor
 {
 	public function getAsString()
 	{

src/Sql/Functors/SqlBinaryOperatorFunctor.php

@@ -0,0 +1,22 @@
+<?php
+abstract class SqlBinaryOperatorFunctor extends SqlFunctionFunctor
+{
+	public function getFunctionName()
+	{
+		throw new Exception('Not implemented');
+	}
+
+	public function getArgumentCount()
+	{
+		return 2;
+	}
+
+	public function getAsString()
+	{
+		return self::surroundBraces($this->subjects[0])
+			. ' ' . $this->getOperator()
+			. ' ' . self::surroundBraces($this->subjects[1]);
+	}
+
+	protected abstract function getOperator();
+}

src/Sql/Functors/SqlFunctionFunctor.php

@@ -0,0 +1,30 @@
+<?php
+abstract class SqlFunctionFunctor extends SqlFunctor
+{
+	protected $subjects;
+
+	public function __construct()
+	{
+		$subjects = func_get_args();
+		$expectedArgumentCount = (array) $this->getArgumentCount();
+		if (!in_array(count($subjects), $expectedArgumentCount))
+			throw new Exception('Unepxected argument count for ' . get_called_class());
+
+		foreach ($subjects as $subject)
+			$this->subjects []= $this->attachExpression($subject);
+	}
+
+	protected abstract function getFunctionName();
+	protected abstract function getArgumentCount();
+
+	public function getAsString()
+	{
+		return $this->getFunctionName()
+			. ' ('
+			. join(', ', array_map(function($subject)
+				{
+					return self::surroundBraces($subject);
+				}, $this->subjects))
+			. ')';
+	}
+}

src/Sql/Functors/SqlFunctor.php

@@ -0,0 +1,4 @@
+<?php
+abstract class SqlFunctor extends SqlExpression
+{
+}

src/Sql/Functors/SqlVariableFunctor.php

@@ -1,5 +1,5 @@
 <?php
-abstract class SqlVariableOperator extends SqlOperator
+abstract class SqlVariableFunctor extends SqlFunctor
 {
 	protected $subjects;
 

src/Sql/Operators/BinaryOperators/SqlAdditionOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlAdditionOperator extends SqlBinaryOperator
-{
-	public function __construct($subject, $target)
-	{
-		parent::__construct($subject, $target, '+');
-	}
-}

src/Sql/Operators/BinaryOperators/SqlAliasOperator.php

@@ -1,13 +0,0 @@
-<?php
-class SqlAliasOperator extends SqlBinaryOperator
-{
-	public function __construct($subject, $target)
-	{
-		parent::__construct($subject, $target, 'AS');
-	}
-
-	public function getAsString()
-	{
-		return '(' . $this->subject->getAsString() . ') ' . $this->operator . ' ' . $this->target->getAsString();
-	}
-}

src/Sql/Operators/BinaryOperators/SqlEqualsOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlEqualsOperator extends SqlBinaryOperator
-{
-	public function __construct($subject, $target)
-	{
-		parent::__construct($subject, $target, '=');
-	}
-}

src/Sql/Operators/BinaryOperators/SqlEqualsOrGreaterOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlEqualsOrGreaterOperator extends SqlBinaryOperator
-{
-	public function __construct($subject, $target)
-	{
-		parent::__construct($subject, $target, '>=');
-	}
-}

src/Sql/Operators/BinaryOperators/SqlEqualsOrLesserOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlEqualsOrLesserOperator extends SqlBinaryOperator
-{
-	public function __construct($subject, $target)
-	{
-		parent::__construct($subject, $target, '<=');
-	}
-}

src/Sql/Operators/BinaryOperators/SqlGreaterOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlGreaterOperator extends SqlBinaryOperator
-{
-	public function __construct($subject, $target)
-	{
-		parent::__construct($subject, $target, '>');
-	}
-}

src/Sql/Operators/BinaryOperators/SqlLesserOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlLesserOperator extends SqlBinaryOperator
-{
-	public function __construct($subject, $target)
-	{
-		parent::__construct($subject, $target, '<');
-	}
-}

src/Sql/Operators/BinaryOperators/SqlLikeOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlLikeOperator extends SqlBinaryOperator
-{
-	public function __construct($subject, $target)
-	{
-		parent::__construct($subject, $target, 'LIKE');
-	}
-}

src/Sql/Operators/BinaryOperators/SqlSubtractionOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlSubtractionOperator extends SqlBinaryOperator
-{
-	public function __construct($subject, $target)
-	{
-		parent::__construct($subject, $target, '-');
-	}
-}

src/Sql/Operators/MiscOperators/SqlIfNullOperator.php

@@ -1,17 +0,0 @@
-<?php
-class SqlIfNullOperator extends SqlOperator
-{
-	protected $subject;
-	protected $target;
-
-	public function __construct($subject, $target)
-	{
-		$this->subject = $this->attachExpression($subject);
-		$this->target = $this->attachExpression($target);
-	}
-
-	public function getAsString()
-	{
-		return 'IFNULL (' . $this->subject->getAsString() . ', ' . $this->target->getAsString() . ')';
-	}
-}

src/Sql/Operators/NullaryOperators/SqlRandomOperator.php

@@ -1,11 +0,0 @@
-<?php
-class SqlRandomOperator extends SqlNullaryOperator
-{
-	public function getAsString()
-	{
-		$config = \Chibi\Registry::getConfig();
-		return $config->main->dbDriver == 'sqlite'
-			? 'RANDOM()'
-			: 'RAND()';
-	}
-}

src/Sql/Operators/SqlBinaryOperator.php

@@ -1,19 +0,0 @@
-<?php
-class SqlBinaryOperator extends SqlOperator
-{
-	protected $subject;
-	protected $target;
-	protected $operator;
-
-	public function __construct($subject, $target, $operator)
-	{
-		$this->subject = $this->attachExpression($subject);
-		$this->target = $this->attachExpression($target);
-		$this->operator = $operator;
-	}
-
-	public function getAsString()
-	{
-		return '(' . $this->subject->getAsString() . ') ' . $this->operator . ' (' . $this->target->getAsString() . ')';
-	}
-}

src/Sql/Operators/SqlNullaryOperator.php

@@ -1,4 +0,0 @@
-<?php
-abstract class SqlNullaryOperator extends SqlOperator
-{
-}

src/Sql/Operators/SqlOperator.php

@@ -1,4 +0,0 @@
-<?php
-abstract class SqlOperator extends SqlExpression
-{
-}

src/Sql/Operators/SqlUnaryOperator.php

@@ -1,25 +0,0 @@
-<?php
-abstract class SqlUnaryOperator extends SqlOperator
-{
-	protected $subject;
-
-	public function __construct($subject)
-	{
-		$this->subject = $this->attachExpression($subject);
-	}
-
-	public function getAsString()
-	{
-		if (empty($this->subject->getAsString()))
-			return $this->getAsStringEmpty();
-
-		return $this->getAsStringNonEmpty();
-	}
-
-	public function getAsStringEmpty()
-	{
-		return '';
-	}
-
-	public abstract function getAsStringNonEmpty();
-}

src/Sql/Operators/UnaryOperators/SqlAbsOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlAbsOperator extends SqlUnaryOperator
-{
-	public function getAsStringNonEmpty()
-	{
-		return 'ABS (' . $this->subject->getAsString() . ')';
-	}
-}

src/Sql/Operators/UnaryOperators/SqlCountOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlCountOperator extends SqlUnaryOperator
-{
-	public function getAsStringNonEmpty()
-	{
-		return 'COUNT (' . $this->subject->getAsString() . ')';
-	}
-}

src/Sql/Operators/UnaryOperators/SqlExistsOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlExistsOperator extends SqlUnaryOperator
-{
-	public function getAsStringNonEmpty()
-	{
-		return 'EXISTS (' . $this->subject->getAsString() . ')';
-	}
-}

src/Sql/Operators/UnaryOperators/SqlIsNullOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlIsNullOperator extends SqlUnaryOperator
-{
-	public function getAsStringNonEmpty()
-	{
-		return '(' . $this->subject->getAsString() . ') IS NULL';
-	}
-}

src/Sql/Operators/UnaryOperators/SqlMaxOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlMaxOperator extends SqlUnaryOperator
-{
-	public function getAsStringNonEmpty()
-	{
-		return 'MAX (' . $this->subject->getAsString() . ')';
-	}
-}

src/Sql/Operators/UnaryOperators/SqlNegationOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlNegationOperator extends SqlUnaryOperator
-{
-	public function getAsStringNonEmpty()
-	{
-		return 'NOT (' . $this->subject->getAsString() . ')';
-	}
-}

src/Sql/Operators/UnaryOperators/SqlNoCaseOperator.php

@@ -1,8 +0,0 @@
-<?php
-class SqlNoCaseOperator extends SqlUnaryOperator
-{
-	public function getAsStringNonEmpty()
-	{
-		return $this->subject->getAsString() . ' COLLATE NOCASE';
-	}
-}

src/Sql/SqlExpression.php

@@ -12,6 +12,13 @@ abstract class SqlExpression
 		return $this;
 	}
 
+	protected static function surroundBraces(SqlExpression $object)
+	{
+		if ($object instanceof SqlStatement)
+			return '(' . $object->getAsString() . ')';
+		return $object->getAsString();
+	}
+
 	public function getBindings()
 	{
 		$bindings = $this->bindings;

src/Sql/Statements/SqlSelectStatement.php

@@ -154,7 +154,7 @@ class SqlSelectStatement extends SqlStatement
 			}, $this->columns));
 		else
 			$sql .= '1';
-		$sql .= ' FROM (' . $this->source->getAsString() . ')';
+		$sql .= ' FROM ' . self::surroundBraces($this->source);
 
 		foreach ($this->innerJoins as $join)
 		{