- More work done on Update, Insert and Delete clause

- Added TOP property to select and delete to fit MSSQL limit's term.
- Added a new interface allowing object's manipulation on save() and load() queries

src/QueryBuilder.php

@@ -25,7 +25,7 @@ class QueryBuilder
 
     public function select($field) : self
     {
-        if ( false !== ( $select = $this->has(Query\Select::class) ) ) {
+        if ( null !== ( $select = $this->getFragment(Query\Select::class) ) ) {
             $select->add($field);
         }
         else {
@@ -39,7 +39,7 @@ class QueryBuilder
     
     public function insert(array $fieldlist, string $table, ? string $alias = null, ? string $database = null, ? string $schema = null) : self
     {
-        if ( ! $this->has(Query\Insert::class) ) {            
+        if ( null === $this->getFragment(Query\Insert::class) ) {            
             if ( $database ) {
                 $table = "\"$database\".$table";
             }
@@ -61,8 +61,7 @@ class QueryBuilder
 
     public function values(array $dataset) : self 
     {
-        
-        if ( false === ( $values = $this->has(Query\Values::class) ) ) {
+        if ( null === ( $values = $this->getFragment(Query\Values::class) ) ) {
             $values = new Query\Values($this);
             $this->push($values);
         }
@@ -74,7 +73,7 @@ class QueryBuilder
     
     public function update(string $table, ? string $alias = null, ? string $database = null, ? string $schema = null) : self
     {
-        if ( ! $this->has(Query\Update::class) ) {            
+        if ( ! $this->getFragment(Query\Update::class) ) {            
             if ( $database ) {
                 $table = "\"$database\".$table";
             }
@@ -96,7 +95,7 @@ class QueryBuilder
     public function set(array $dataset) : self 
     {
         
-        if ( false === ( $values = $this->has(Query\Set::class) ) ) {
+        if ( null === ( $values = $this->getFragment(Query\Set::class) ) ) {
             $set = new Query\Set($this);
             $this->push($set);
         }
@@ -108,7 +107,7 @@ class QueryBuilder
     
     public function delete() : self
     {
-        if ( ! $this->has(Query\Delete::class) ) {
+        if ( ! $this->getFragment(Query\Delete::class) ) {
             $this->push(new Query\Delete());
         }
 
@@ -125,14 +124,14 @@ class QueryBuilder
             $table = "\"$schema\".$table";
         }
 
-        if ( false !== ( $from = $this->has(Query\From::class) ) ) {
+        if ( null !== ( $from = $this->getFragment(Query\From::class) ) ) {
             $from->add($alias ? [ $alias => $table ] : $table);
         }
         else {
             $from = new Query\From($this);
             $this->push($from);
             
-            $from->set($alias ? [ $alias => $table ] : $table);
+            $from->set($alias ? [ $alias => $table ] : [ $table ]);
         }
 
         return $this;
@@ -140,7 +139,7 @@ class QueryBuilder
 
     public function open(string $condition = Query\Where::CONDITION_AND) : self
     {
-        if ( false !== ($this->where ?? false) ) {
+        if ( null !== ($this->where ?? false) ) {
             $this->where->conditionList[] = $new = new Query\Where($this, $condition);
             $this->where = $new;
         }
@@ -150,7 +149,7 @@ class QueryBuilder
 
     public function close() : self
     {
-        if ( false !== ($this->where ?? false) && $this->where->parent ) {
+        if ( null !== ($this->where ?? false) && $this->where->parent ) {
             $this->where = $this->where->parent;
         }
 
@@ -162,7 +161,7 @@ class QueryBuilder
         if ( $this->where ?? false ) {
             $where = $this->where;
         }
-        elseif ( false === ( $where = $this->has(Query\Where::class) ) ) {
+        elseif ( null === ( $where = $this->getFragment(Query\Where::class) ) ) {
             $this->where = $where = new Query\Where($this);
             $this->push($where);
         }
@@ -186,29 +185,31 @@ class QueryBuilder
 
     public function limit(int $value) : self
     {
-        if ( false === $limit = $this->has(Query\Limit::class) ) {
+        if ( null === $limit = $this->getFragment(Query\Limit::class) ) {
             $limit = new Query\Limit();
             $this->push($limit);
         }
 
         $limit->set($value);
+        
         return $this;
     }
 
     public function offset(int $value) : self
     {
-        if ( false === $offset = $this->has(Query\Offset::class) ) {
+        if ( null === $offset = $this->getFragment(Query\Offset::class) ) {
             $offset = new Query\Offset();
             $this->push($offset);
         }
 
         $offset->set($value);
+        
         return $this;
     }
 
     public function orderBy(string $field, ? string $direction = null) : self
     {
-        if ( false === $orderBy = $this->has(Query\OrderBy::class) ) {
+        if ( null === $orderBy = $this->getFragment(Query\OrderBy::class) ) {
             $orderBy = new Query\OrderBy();
             $this->push($orderBy);
         }
@@ -240,16 +241,26 @@ class QueryBuilder
         return implode(" ", $sql);
     }
 
-    public function has($class) {
+    public function getFragment(string $class) : ? Query\Fragment
+    {
         foreach($this->queryStack as $item) {
             if ( get_class($item) === $class ) {
                 return $item;
             }
         }
 
-        return false;
+        return null;
     }
 
+    public function removeFragment(Query\Fragment $fragment) : void
+    {
+        foreach($this->queryStack as $key => $item) {
+            if ( $item === $fragment ) {
+                unset($this->queryStack[$key]);
+            }
+        }
+    }
+    
     public function __toString() : string
     {
         return $this->render();