1 files changed, 106 insertions, 0 deletions
diff --git a/grc/core/Element.py b/grc/core/Element.py
new file mode 100644
index 0000000000..c999d6704f
--- /dev/null
+++ b/grc/core/Element.py
@@ -0,0 +1,106 @@
+"""
+Copyright 2008, 2009, 2015 Free Software Foundation, Inc.
+This file is part of GNU Radio
+
+GNU Radio Companion is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+GNU Radio Companion is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+"""
+
+
+class Element(object):
+
+    def __init__(self, parent=None):
+        self._parent = parent
+        self._error_messages = list()
+
+    ##################################################
+    # Element Validation API
+    ##################################################
+    def validate(self):
+        """
+        Validate this element and call validate on all children.
+        Call this base method before adding error messages in the subclass.
+        """
+        del self._error_messages[:]
+        for child in self.get_children():
+            child.validate()
+
+    def is_valid(self):
+        """
+        Is this element valid?
+
+        Returns:
+            true when the element is enabled and has no error messages
+        """
+        return not self.get_error_messages() or not self.get_enabled()
+
+    def add_error_message(self, msg):
+        """
+        Add an error message to the list of errors.
+
+        Args:
+            msg: the error message string
+        """
+        self._error_messages.append(msg)
+
+    def get_error_messages(self):
+        """
+        Get the list of error messages from this element and all of its children.
+        Do not include the error messages from disabled children.
+        Cleverly indent the children error messages for printing purposes.
+
+        Returns:
+            a list of error message strings
+        """
+        error_messages = list(self._error_messages)  # Make a copy
+        for child in filter(lambda c: c.get_enabled(), self.get_children()):
+            for msg in child.get_error_messages():
+                error_messages.append("{}:\n\t{}".format(child, msg.replace("\n", "\n\t")))
+        return error_messages
+
+    def rewrite(self):
+        """
+        Rewrite this element and call rewrite on all children.
+        Call this base method before rewriting the element.
+        """
+        for child in self.get_children():
+            child.rewrite()
+
+    def get_enabled(self):
+        return True
+
+    ##############################################
+    # Tree-like API
+    ##############################################
+    def get_parent(self):
+        return self._parent
+
+    def get_children(self):
+        return list()
+
+    ##############################################
+    # Type testing
+    ##############################################
+    is_platform = False
+
+    is_flow_graph = False
+
+    is_block = False
+    is_dummy_block = False
+
+    is_connection = False
+
+    is_port = False
+
+    is_param = False