Creating initial framework for refactoring core codebase

lib/v2/playbook/conditional.py

@@ -0,0 +1,78 @@
+# (c) 2012-2014, Michael DeHaan <michael.dehaan@gmail.com>
+#
+# This file is part of Ansible
+#
+# Ansible 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 3 of the License, or
+# (at your option) any later version.
+#
+# Ansible 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 Ansible.  If not, see <http://www.gnu.org/licenses/>.
+
+import v2.config as C
+from v2.utils import template
+from v2.utils import list_union
+
+class Conditional(object):
+    def __init__(self, basedir, conditionals=[]):
+        self.basedir = basedir
+        self.conditionals = conditionals
+
+    def push(self, conditional):
+        if conditional not in self.conditionals:
+            self.conditionals.append(conditional)
+
+    def get_conditionals(self):
+        # return a full slice to make sure the reference
+        # doesn't get mangled by other users of the result
+        return self.conditionals[:]
+
+    def merge(self, conditional):
+        if isinstance(conditional, basestring):
+            conditional = Conditional(self.basedir, [conditional])
+        elif isinstance(conditional, list):
+            conditional = Conditional(self.basedir, conditional)
+        elif not isinstance(conditional, Conditional):
+            raise AnsibleError('expected a Conditional() class, instead got a %s' % type(conditional))
+        self.conditionals = list_union(self.conditionals, conditional.get_conditonals())
+
+    def evaluate(self, inject):
+        for conditional in self.conditional:
+            if not self._do_evaluate(conditional, inject):
+                return False
+        return True
+
+    def _do_evaluate(self, conditional, inject):
+        # allow variable names
+        if conditional in inject and '-' not in str(inject[conditional]):
+            conditional = inject[conditional]
+        conditional = template.template(self.basedir, conditional, inject, fail_on_undefined=C.fail_on_undefined)
+        original = str(conditional).replace("jinja2_compare ","")
+        # a Jinja2 evaluation that results in something Python can eval!
+        presented = "{%% if %s %%} True {%% else %%} False {%% endif %%}" % conditional
+        conditional = template.template(self.basedir, presented, inject)
+        val = conditional.strip()
+        if val == presented:
+            # the templating failed, meaning most likely a
+            # variable was undefined. If we happened to be
+            # looking for an undefined variable, return True,
+            # otherwise fail
+            if "is undefined" in conditional:
+                return True
+            elif "is defined" in conditional:
+                return False
+            else:
+                raise errors.AnsibleError("error while evaluating conditional: %s" % original)
+        elif val == "True":
+            return True
+        elif val == "False":
+            return False
+        else:
+            raise errors.AnsibleError("unable to evaluate conditional: %s" % original)
+