1 files changed, 117 insertions, 0 deletions
diff --git a/grc/core/utils/descriptors/evaluated.py b/grc/core/utils/descriptors/evaluated.py
new file mode 100644
index 0000000000..0e1b68761c
--- /dev/null
+++ b/grc/core/utils/descriptors/evaluated.py
@@ -0,0 +1,117 @@
+# Copyright 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
+
+from __future__ import absolute_import
+
+import six
+
+
+class Evaluated(object):
+    def __init__(self, expected_type, default, name=None):
+        self.expected_type = expected_type
+        self.default = default
+
+        self.name = name or 'evaled_property_{}'.format(id(self))
+        self.eval_function = self.default_eval_func
+
+    @property
+    def name_raw(self):
+        return '_' + self.name
+
+    def default_eval_func(self, instance):
+        raw = getattr(instance, self.name_raw)
+        try:
+            value = instance.parent_block.evaluate(raw)
+        except Exception as error:
+            if raw:
+                instance.add_error_message("Failed to eval '{}': {}".format(raw, error))
+            return self.default
+
+        if not isinstance(value, self.expected_type):
+            instance.add_error_message("Can not cast evaluated value '{}' to type {}"
+                                       "".format(value, self.expected_type))
+            return self.default
+        # print(instance, self.name, raw, value)
+        return value
+
+    def __call__(self, func):
+        self.name = func.__name__
+        self.eval_function = func
+        return self
+
+    def __get__(self, instance, owner):
+        if instance is None:
+            return self
+        attribs = instance.__dict__
+        try:
+            value = attribs[self.name]
+        except KeyError:
+            value = attribs[self.name] = self.eval_function(instance)
+        return value
+
+    def __set__(self, instance, value):
+        attribs = instance.__dict__
+        value = value or self.default
+        if isinstance(value, six.text_type) and value.startswith('${') and value.endswith('}'):
+            attribs[self.name_raw] = value[2:-1].strip()
+        else:
+            attribs[self.name] = type(self.default)(value)
+
+    def __delete__(self, instance):
+        attribs = instance.__dict__
+        if self.name_raw in attribs:
+            attribs.pop(self.name, None)
+
+
+class EvaluatedEnum(Evaluated):
+    def __init__(self, allowed_values, default=None, name=None):
+        if isinstance(allowed_values, six.string_types):
+            allowed_values = set(allowed_values.split())
+        self.allowed_values = allowed_values
+        default = default if default is not None else next(iter(self.allowed_values))
+        super(EvaluatedEnum, self).__init__(str, default, name)
+
+    def default_eval_func(self, instance):
+        value = super(EvaluatedEnum, self).default_eval_func(instance)
+        if value not in self.allowed_values:
+            instance.add_error_message("Value '{}' not in allowed values".format(value))
+            return self.default
+        return value
+
+
+class EvaluatedPInt(Evaluated):
+    def __init__(self, name=None):
+        super(EvaluatedPInt, self).__init__(int, 1, name)
+
+    def default_eval_func(self, instance):
+        value = super(EvaluatedPInt, self).default_eval_func(instance)
+        if value < 1:
+            # todo: log
+            return self.default
+        return value
+
+
+class EvaluatedFlag(Evaluated):
+    def __init__(self, name=None):
+        super(EvaluatedFlag, self).__init__((bool, int), False, name)
+
+
+def setup_names(cls):
+    for name, attrib in cls.__dict__.items():
+        if isinstance(attrib, Evaluated):
+            attrib.name = name
+    return cls