import ruamel.yaml as yaml
import schema
from ..exceptions import StatechartError
from ..model import Statechart
from .datadict import export_to_dict, import_from_dict
__all__ = ['import_from_yaml', 'export_to_yaml']
class SCHEMA:
contract = {schema.Or('before', 'after', 'always'): schema.Use(str)}
transition = {
schema.Optional('target'): schema.Use(str),
schema.Optional('event'): schema.Use(str),
schema.Optional('guard'): schema.Use(str),
schema.Optional('action'): schema.Use(str),
schema.Optional('contract'): [contract],
schema.Optional('priority'): schema.Or(schema.Use(int), 'high', 'low'),
}
state = dict() # type: ignore
state.update({
'name': schema.Use(str),
schema.Optional('type'): schema.Or('final', 'shallow history', 'deep history'),
schema.Optional('on entry'): schema.Use(str),
schema.Optional('on exit'): schema.Use(str),
schema.Optional('transitions'): [transition],
schema.Optional('contract'): [contract],
schema.Optional('initial'): schema.Use(str),
schema.Optional('parallel states'): [state],
schema.Optional('states'): [state],
schema.Optional('memory'): schema.Use(str),
})
statechart = {
'statechart': {
'name': schema.Use(str),
schema.Optional('description'): schema.Use(str),
schema.Optional('preamble'): schema.Use(str),
'root state': state,
}
}
def import_from_yaml(text: str=None, filepath: str=None, *, ignore_schema: bool=False, ignore_validation: bool=False) -> Statechart:
"""
Import a statechart from a YAML representation (first argument) or a YAML file (filepath argument).
Unless specified, the structure contained in the YAML is validated against a predefined
schema (see *sismic.io.SCHEMA*), and the resulting statechart is validated using its *validate()* method.
:param text: A YAML text. If not provided, filepath argument has to be provided.
:param filepath: A path to a YAML file.
:param ignore_schema: set to *True* to disable yaml validation.
:param ignore_validation: set to *True* to disable statechart validation.
:return: a *Statechart* instance
"""
if not text and not filepath:
raise TypeError('A YAML must be provided, either using first argument or filepath argument.')
elif text and filepath:
raise TypeError('Either provide first argument or filepath argument, not both.')
elif filepath:
with open(filepath, 'r') as f:
text = f.read()
if yaml.version_info < (0, 15):
data = yaml.safe_load(text) # type: dict
else:
yml = yaml.YAML(typ='safe', pure=True)
data = yml.load(text)
if not ignore_schema:
try:
data = schema.Schema(SCHEMA.statechart).validate(data)
except schema.SchemaError as e:
raise StatechartError('YAML validation failed') from e
sc = import_from_dict(data)
if not ignore_validation:
sc.validate()
return sc
def export_to_yaml(statechart: Statechart, filepath: str=None) -> str:
"""
Export given *Statechart* instance to YAML. Its YAML representation is returned by this function.
Automatically save the output to filepath, if provided.
:param statechart: statechart to export
:param filepath: save output to given filepath, if provided
:return: A textual YAML representation
"""
output = yaml.dump(export_to_dict(statechart, ordered=False),
width=1000, default_flow_style=False)
if filepath:
with open(filepath, 'w') as f:
f.write(output)
return output
