added the ast class for ALTER VIEW

Author: MinuraPunchihewa

mindsdb_sql_parser/ast/mindsdb/alter_view.py

@@ -0,0 +1,49 @@
+from mindsdb_sql_parser.ast.base import ASTNode
+from mindsdb_sql_parser.utils import indent
+from mindsdb_sql_parser.ast.select.identifier import Identifier
+
+
+class AlterView(ASTNode):
+    """
+    Alter a view.
+    """
+    def __init__(
+        self,
+        name: Identifier,
+        query_str: str,
+        from_table: Identifier = None,
+        *args, 
+        **kwargs
+    ):
+        """
+        Args:
+            name: Identifier -- name of the view to alter.
+            query_str: str -- the new query string for the view.
+            from_table: Identifier -- optional table to alter the view from.
+        """
+        super().__init__(*args, **kwargs)
+        self.name = name
+        self.query_str = query_str
+        self.from_table = from_table
+
+    def to_tree(self, *args, level=0, **kwargs):
+        ind = indent(level)
+        ind1 = indent(level+1)
+
+        name_str = f'\n{ind1}name={self.name.to_string()},'
+        from_table_str = f'\n{ind1}from_table=\n{self.from_table.to_tree(level=level+2)},' if self.from_table else ''
+        query_str = f'\n{ind1}query="{self.query_str}"'
+
+        out_str = f'{ind}AlterView(' \
+                  f'{name_str}' \
+                  f'{query_str}' \
+                  f'{from_table_str}' \
+                  f'\n{ind})'
+        return out_str
+    
+    def get_string(self, *args, **kwargs):
+        from_str = f' FROM {str(self.from_table)} ' if self.from_table else ''
+
+        out_str = f'ALTER VIEW {self.name.to_string()} AS ( {self.query_str} ){from_str}'
+
+        return out_str