Add iterators for non pdo drivers.

Allows result sets to be iterated over without running out of memory on
large data sets.

lib/Doctrine/DBAL/Driver/AbstractIterator.php

+<?php
+
+namespace Doctrine\DBAL\Driver;
+
+abstract class AbstractIterator
+{
+    protected $cursor;
+    protected $key;
+    protected $current;
+    protected $fetched = 0;
+    protected $defaultFetchMode;
+
+    public function __construct($cursor, $defaultFetchMode = \PDO::FETCH_BOTH)
+    {
+        $this->cursor = $cursor;
+        $this->defaultFetchMode = $defaultFetchMode;
+        $this->next();
+    }
+
+    public function current()
+    {
+        return $this->current;
+    }
+
+    public function next()
+    {
+        $this->key = $this->fetched;
+        $this->current = $this->fetch();
+
+        if ($this->current) {
+            $this->fetched++;
+        }
+    }
+
+    public function key()
+    {
+        return $this->key;
+    }
+
+    public function valid()
+    {
+        return (bool)$this->current;
+    }
+
+    public function rewind()
+    {
+        // Not supported
+    }
+
+    abstract protected function fetch();
+}

lib/Doctrine/DBAL/Driver/IBMDB2/DB2Iterator.php

+<?php
+
+namespace Doctrine\DBAL\Driver\IBMDB2;
+
+use Doctrine\DBAL\Driver\AbstractIterator;
+
+class DB2Iterator extends AbstractIterator implements \Iterator
+{
+    protected function fetch()
+    {
+        switch ($this->defaultFetchMode) {
+            case \PDO::FETCH_BOTH:
+                return db2_fetch_both($this->cursor);
+            case \PDO::FETCH_ASSOC:
+                return db2_fetch_assoc($this->cursor);
+            case \PDO::FETCH_CLASS:
+                return db2_fetch_object($this->cursor);
+            case \PDO::FETCH_NUM:
+                return db2_fetch_array($this->cursor);
+            case \PDO::FETCH_OBJ:
+                return db2_fetch_object($this->cursor);
+            default:
+                throw new DB2Exception("Given Fetch-Style " . $this->defaultFetchMode . " is not supported.");
+        }
+    }
+}

lib/Doctrine/DBAL/Driver/IBMDB2/DB2Statement.php

@@ -199,9 +199,7 @@ class DB2Statement implements \IteratorAggregate, Statement
      */
     public function getIterator()
     {
-        $data = $this->fetchAll();
-
-        return new \ArrayIterator($data);
+        return new DB2Iterator($this->_stmt, $this->_defaultFetchMode);
     }
 
     /**

lib/Doctrine/DBAL/Driver/Mysqli/MysqliIterator.php

+<?php
+
+namespace Doctrine\DBAL\Driver\Mysqli;
+
+use Doctrine\DBAL\Driver\AbstractIterator;
+
+class MysqliIterator extends AbstractIterator implements \Iterator
+{
+    protected function fetch()
+    {
+        switch ($this->defaultFetchMode) {
+            case \PDO::FETCH_COLUMN:
+                return $this->fetchColumn();
+            default:
+                return $this->fetch($this->defaultFetchMode);
+        }
+    }
+}

lib/Doctrine/DBAL/Driver/Mysqli/MysqliStatement.php

@@ -406,8 +406,6 @@ class MysqliStatement implements \IteratorAggregate, Statement
      */
     public function getIterator()
     {
-        $data = $this->fetchAll();
-
-        return new \ArrayIterator($data);
+        return new MysqliIterator($this->_stmt, $this->_defaultFetchMode);
     }
 }

lib/Doctrine/DBAL/Driver/OCI8/OCI8Iterator.php

+<?php
+
+namespace Doctrine\DBAL\Driver\OCI8;
+
+use Doctrine\DBAL\Driver\AbstractIterator;
+
+class OCI8Iterator extends AbstractIterator implements \Iterator
+{
+    private static $fetchModeMap = array(
+        \PDO::FETCH_BOTH => OCI_BOTH,
+        \PDO::FETCH_ASSOC => OCI_ASSOC,
+        \PDO::FETCH_NUM => OCI_NUM,
+        \PDO::FETCH_COLUMN => OCI_NUM,
+    );
+
+    protected function fetch()
+    {
+        $result = [];
+
+        if (\PDO::FETCH_OBJ === $this->defaultFetchMode) {
+            return oci_fetch_object($this->cursor);
+        }
+
+        if (self::$fetchModeMap[$this->defaultFetchMode] === OCI_BOTH) {
+            return oci_fetch_array(
+                $this->cursor,
+                $this->defaultFetchMode | OCI_RETURN_NULLS | OCI_RETURN_LOBS
+            );
+        }
+
+        $fetchStructure = OCI_FETCHSTATEMENT_BY_ROW;
+        if ($this->defaultFetchMode === \PDO::FETCH_COLUMN) {
+            $fetchStructure = OCI_FETCHSTATEMENT_BY_COLUMN;
+        }
+
+        oci_fetch_all(
+            $this->cursor,
+            $result,
+            0,
+            -1,
+            self::$fetchModeMap[$this->defaultFetchMode] | OCI_RETURN_NULLS | $fetchStructure | OCI_RETURN_LOBS
+        );
+
+        return $result;
+    }
+}

lib/Doctrine/DBAL/Driver/OCI8/OCI8Statement.php

@@ -20,6 +20,7 @@
 namespace Doctrine\DBAL\Driver\OCI8;
 
 use Doctrine\DBAL\Driver\Statement;
+use \IteratorAggregate;
 use PDO;
 
 /**
@@ -28,7 +29,7 @@ use PDO;
  * @since 2.0
  * @author Roman Borschel <roman@code-factory.org>
  */
-class OCI8Statement implements \IteratorAggregate, Statement
+class OCI8Statement implements IteratorAggregate, Statement
 {
     /**
      * @var resource
@@ -369,9 +370,7 @@ class OCI8Statement implements \IteratorAggregate, Statement
      */
     public function getIterator()
     {
-        $data = $this->fetchAll();
-
-        return new \ArrayIterator($data);
+        return new OCI8Iterator($this->_sth, $this->_defaultFetchMode);
     }
 
     /**

lib/Doctrine/DBAL/Driver/SQLAnywhere/SQLAnywhereIterator.php

+<?php
+
+namespace Doctrine\DBAL\Driver\SQLAnywhere;
+
+use Doctrine\DBAL\Driver\AbstractIterator;
+
+class SQLAnywhereIterator extends AbstractIterator implements \Iterator
+{
+    protected function fetch()
+    {
+        $result = sasql_stmt_result_metadata($this->cursor);
+
+        switch ($this->defaultFetchMode) {
+            case \PDO::FETCH_ASSOC:
+                return sasql_fetch_assoc($this->cursor);
+            case \PDO::FETCH_BOTH:
+                return sasql_fetch_array($result, SASQL_BOTH);
+            case \PDO::FETCH_CLASS:
+                return sasql_fetch_object($result);
+            case \PDO::FETCH_NUM:
+                return sasql_fetch_row($result);
+            case \PDO::FETCH_OBJ:
+                return sasql_fetch_object($result);
+            default:
+                throw new SQLAnywhereException('Fetch mode is not supported: ' . $this->defaultFetchMode);
+        }
+    }
+}

lib/Doctrine/DBAL/Driver/SQLAnywhere/SQLAnywhereStatement.php

@@ -278,7 +278,7 @@ class SQLAnywhereStatement implements IteratorAggregate, Statement
      */
     public function getIterator()
     {
-        return new \ArrayIterator($this->fetchAll());
+        return new SQLAnywhereIterator($this->stmt, $this->defaultFetchMode);
     }
 
     /**

lib/Doctrine/DBAL/Driver/SQLSrv/SQLSrvIterator.php

+<?php
+
+namespace Doctrine\DBAL\Driver\SQLSrv;
+
+use Doctrine\DBAL\Driver\AbstractIterator;
+
+class SQLSrvIterator extends AbstractIterator implements \Iterator
+{
+    protected function fetch()
+    {
+        return sqlsrv_fetch_array($this->cursor, $this->defaultFetchMode);
+    }
+}

lib/Doctrine/DBAL/Driver/SQLSrv/SQLSrvStatement.php

@@ -295,9 +295,7 @@ class SQLSrvStatement implements IteratorAggregate, Statement
      */
     public function getIterator()
     {
-        $data = $this->fetchAll();
-
-        return new \ArrayIterator($data);
+        return new SQLSrvIterator($this->stmt, $this->defaultFetchMode);
     }
 
     /**