ClingoBackend#

Implements all basic clingo’s API functionality. This includes grounding, solving, cautious and brave resoning, use of extenrals and assuptions, and optimization

Examples

Public operations#

Can be used as OPERATION in the actions of the ui-state

class ClingoBackend[source]#

Bases: object

This backend contains the basic clingo functionality for a backend using clingo.

add_assumption(atom, value='true')[source]#

Adds an atom a as an assumption.

If the value is “true”, the atom is assumed to be true. This assumption can be considered as an integrity constraint: :- not a. forcing the program to entail the given atom.

If the value is “false”, the atom is assumed to be false: This assumption can be considered as an integrity constraint: :- a. forcing the program to never entail the given atom.

Notice that the assumption must be generated by your domain encoding.

Parameters

atom (str) – The clingo symbol to be added as a true assumption
value (str) – The value of the assumption either “true” or “false”

add_atom(predicate)[source]#

Adds an atom, restarts the control and grounds

Parameters: predicate (str) – The clingo symbol to be added

clear_assumptions()[source]#: Removes all assumptions.

clear_atoms()[source]#: Removes all atoms and resets the backend. and finally updates the model and returns the updated gui as a Json structure.

download(show_prg=None, file_name='clinguin_download.lp')[source]#

Downloads the current model. It must be selected first via select .

Parameters

show_prg (_type_, optional) – Program to filter output using show statements. Defaults to None.
file_name (str, optional) – The name of the file for the download. Defaults to “clinguin_download.lp”.

ground(program, arguments=None)[source]#

Grounds the given program. Notice that the base program is grounded when the server starts. This operation can be used for grounding encodings with multiple programs in a multi-shot setting.

Parameters

program (str) – The name of the program to ground used in the #program directive
arguments (tuple, optional) – The list of arguments to ground the program. Defaults to an empty list.
instance (These are the arguments of your #program directive. For) –
step (in #program) –

next_solution(opt_mode='ignore')[source]#

Obtains the next solution. If a no browsing has been started yet, then it calls solve, otherwise it iterates the models in the last call. To keep the atoms shown in the solution, use select.

Parameters: opt_mode – The clingo optimization mode, bu default is ‘ignore’, to browse only optimal models use ‘optN’

remove_assumption(atom)[source]#

Removes an atom from the assumptions list regardless of its value. This will allow the atom to take any value in the solution.

Parameters: atom (str) – The clingo symbol to be removed

remove_assumption_signature(atom)[source]#

Removes from the list of assumptions those matching the given atom. Unlike function remove_assumption, this one allows for partial matches using the placeholder constant any. This will allow the atom to take any value in the solution.

Parameters: atom (str) – The atom description as a symbol, where the reserver word any is used to state that anything can take part of that position. For instance, person(anna,any), will remove all assumptions of atom person, where the first argument is anna.

remove_atom(predicate)[source]#

Removes an atom (if present), restarts the control and grounds again

Parameters: predicate (str) – The clingo symbol to be added

restart()[source]#: Restarts the backend. It will initialize all attributes, remove atoms, assumptions and externals, restart the control object by initializing all parameters, controls, ending the browsing and grounding.

select(show_prg='')[source]#

Select the current solution during browsing. All atoms in the solution are added as assumptions in the backend.

Parameters: show_program (str) – An optional show program to filter atoms

set_constant(name, value)[source]#: Sets a constant value. Will reinitialize the control, ground and set arguments

set_external(atom, value)[source]#

Sets the value of an external. Externals must be defined in the domain files using #external. The truth value of external atoms can then be provided by the user via this function.

Parameters

atom (str) – The clingo symbol to be set
value (str) – The value (release, true or false)

stop_browsing()[source]#: Stops the current browsing.

update()[source]#: Updates the UI by clearing the cache and computing the models again.

Domain state constructors#

property ClingoBackend._ds_context#

Adds context information from the client.

Includes predicate _clinguin_context/2 indicating each key and value in the context.

property ClingoBackend._ds_model#

Computes model and adds all atoms as facts. When the model is being iterated by the user, the current model is returned. It will use as optimality the mode set in the command line as default-opt-mode (ignore by default).