def resolve_scoped_reference(ref, context):
""" Given a reference scope in list format (e.g. ['this', 'key1', 'key2'],
for the reference string 'this.key1.key2',
and a context stack -- a list of nested dictionary references (nodes) --
resolve the reference and return the value
"""
if len(context) == 0:
# TODO: better
raise Exception("Invalid reference", ref)
# pop an element off of the scope list
element_to_resolve = ref.pop(0)
if (element_to_resolve == 'root'):
return resolve_scoped_reference(ref, [context[0]])
if (element_to_resolve == 'parent'):
return resolve_scoped_reference(ref, context[0:-1])
if (element_to_resolve == 'this'):
return resolve_scoped_reference(ref, context)
current_context = context[-1]
# check to see if current_context describes an int
index = None
try:
index = int(current_context)
current_context = context[-2]
except:
pass
if isdict(current_context):
if not element_to_resolve in current_context:
# TODO: make better
raise Exception("Unknown key: %s" % element_to_resolve)
elif isindexable(current_context):
element_to_resolve = int(element_to_resolve)
if not 0 <= element_to_resolve < len(current_context):
raise Exception("Reference index out of range: %d" %
element_to_resolve)
else:
raise Exception("Invalid reference")
resolved_element = current_context[element_to_resolve]
if not index is None:
resolved_element = resolved_element[index]
if len(ref) != 0:
context.append(resolved_element)
return resolve_scoped_reference(ref, context)
return resolved_element
def resolve_scoped_reference(ref, context):
""" Given a reference scope in list format (e.g. ['this', 'key1', 'key2']),
and a context stack (list of nested dictionary references), resolve
the reference and return the value
"""
if len(context) == 0:
# TODO: better
raise Exception("Invalid reference")
# pop an element off of the scope list
element_to_resolve = ref.pop(0)
if element_to_resolve == "root":
return resolve_scoped_reference(ref, [context[0]])
if element_to_resolve == "parent":
return resolve_scoped_reference(ref, context[0:-1])
if element_to_resolve == "this":
return resolve_scoped_reference(ref, context)
current_context = context[-1]
if isdict(current_context):
if not element_to_resolve in current_context:
# TODO: make better
raise Exception("Unknown key: %s" % element_to_resolve)
elif isindexable(current_context):
element_to_resolve = int(element_to_resolve)
if not 0 <= element_to_resolve < len(current_context):
raise Exception("Reference index out of range: %d" % element_to_resolve)
else:
raise Exception("Invalid reference")
resolved_element = current_context[element_to_resolve]
if len(ref) != 0:
context.append(resolved_element)
return resolve_scoped_reference(ref, context)
return resolved_element
def resolve_scoped_reference(ref, context):
""" Given a reference scope in list format (e.g. ['this', 'key1', 'key2']),
and a context stack (list of nested dictionary references), resolve
the reference and return the value
"""
if len(context) == 0:
# TODO: better
raise Exception("Invalid reference")
# pop an element off of the scope list
element_to_resolve = ref.pop(0)
if( element_to_resolve == 'root'):
return resolve_scoped_reference(ref, [context[0]])
if( element_to_resolve == 'parent'):
return resolve_scoped_reference(ref, context[0:-1])
if( element_to_resolve == 'this'):
return resolve_scoped_reference(ref, context)
current_context = context[-1]
if not isdict(current_context):
raise Exception("Invalid reference")
if not element_to_resolve in current_context:
# TODO: make better
raise Exception("Unknown key: %s" % element_to_resolve)
resolved_element = current_context[element_to_resolve]
if len(ref) != 0:
context.append(resolved_element)
return resolve_scoped_reference(ref, context)
return resolved_element
