1 files changed, 164 insertions, 0 deletions
diff --git a/grc/core/base.py b/grc/core/base.py
new file mode 100644
index 0000000000..e5ff657d85
--- /dev/null
+++ b/grc/core/base.py
@@ -0,0 +1,164 @@
+# Copyright 2008, 2009, 2015, 2016 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
+
+import weakref
+
+from .utils.descriptors import lazy_property
+
+
+class Element(object):
+
+    def __init__(self, parent=None):
+        self._parent = weakref.ref(parent) if parent else lambda: None
+        self._error_messages = []
+
+    ##################################################
+    # 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.children():
+            child.validate()
+
+    def is_valid(self):
+        """
+        Is this element valid?
+
+        Returns:
+            true when the element is enabled and has no error messages or is bypassed
+        """
+        if not self.enabled or self.get_bypassed():
+            return True
+        return not next(self.iter_error_messages(), False)
+
+    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 or bypassed children.
+        Cleverly indent the children error messages for printing purposes.
+
+        Returns:
+            a list of error message strings
+        """
+        return [msg if elem is self else "{}:\n\t{}".format(elem, msg.replace("\n", "\n\t"))
+                for elem, msg in self.iter_error_messages()]
+
+    def iter_error_messages(self):
+        """
+        Iterate over error messages. Yields tuples of (element, message)
+        """
+        for msg in self._error_messages:
+            yield self, msg
+        for child in self.children():
+            if not child.enabled or child.get_bypassed():
+                continue
+            for element_msg in child.iter_error_messages():
+                yield element_msg
+
+    def rewrite(self):
+        """
+        Rewrite this element and call rewrite on all children.
+        Call this base method before rewriting the element.
+        """
+        for child in self.children():
+            child.rewrite()
+
+    @property
+    def enabled(self):
+        return True
+
+    def get_bypassed(self):
+        return False
+
+    ##############################################
+    # Tree-like API
+    ##############################################
+    @property
+    def parent(self):
+        return self._parent()
+
+    def get_parent_by_type(self, cls):
+        parent = self.parent
+        if parent is None:
+            return None
+        elif isinstance(parent, cls):
+            return parent
+        else:
+            return parent.get_parent_by_type(cls)
+
+    @lazy_property
+    def parent_platform(self):
+        from .platform import Platform
+        return self.get_parent_by_type(Platform)
+
+    @lazy_property
+    def parent_flowgraph(self):
+        from .FlowGraph import FlowGraph
+        return self.get_parent_by_type(FlowGraph)
+
+    @lazy_property
+    def parent_block(self):
+        from .blocks import Block
+        return self.get_parent_by_type(Block)
+
+    def reset_parents_by_type(self):
+        """Reset all lazy properties"""
+        for name, obj in vars(Element):  # explicitly only in Element, not subclasses
+            if isinstance(obj, lazy_property):
+                delattr(self, name)
+
+    def children(self):
+        return
+        yield  # empty generator
+
+    ##############################################
+    # Type testing
+    ##############################################
+    is_flow_graph = False
+    is_block = False
+    is_dummy_block = False
+    is_connection = False
+    is_port = False
+    is_param = False
+    is_variable = False
+    is_import = False
+
+    def get_raw(self, name):
+        descriptor = getattr(self.__class__, name, None)
+        if not descriptor:
+            raise ValueError("No evaluated property '{}' found".format(name))
+        return getattr(self, descriptor.name_raw, None) or getattr(self, descriptor.name, None)
+
+    def set_evaluated(self, name, value):
+        descriptor = getattr(self.__class__, name, None)
+        if not descriptor:
+            raise ValueError("No evaluated property '{}' found".format(name))
+        self.__dict__[descriptor.name] = value