Module clingox.program

This module provides functions to work with ground programs.

This includes constructing a ground representation using an observer, pretty printing the ground representation, and adding ground program to control objects via the backend.

Example

The following example shows how to:

• use the ProgramObserver to construct a Program, and
• add it to another Control object.

>>> from clingo.control import Control
>>> from clingox.program import Program, ProgramObserver, Remapping
>>>
>>> prg = Program()
>>> ctl_a = Control()
>>> ctl_a.register_observer(ProgramObserver(prg))
>>>
>>> ctl_a.add('base', [], 'a. {b}. c :- b.')
>>> ctl_a.ground([('base', [])])
>>> print(prg)
a.
__x1.
c :- b.
{b}.
>>>
>>> ctl_b = Control(['0'])
>>> with ctl_b.backend() as backend:
...     mapping = Remapping(backend, prg.output_atoms, prg.facts)
...     prg.add_to_backend(backend, mapping)
...
>>> ctl_b.solve(on_model=print)
a
b c a

'''
This module provides functions to work with ground programs.

This includes constructing a ground representation using an observer, pretty
printing the ground representation, and adding ground program to control
objects via the backend.

Example
-------

The following example shows how to:

- use the `ProgramObserver` to construct a `Program`, and
- add it to another `clingo.control.Control` object.

```python-repl
>>> from clingo.control import Control
>>> from clingox.program import Program, ProgramObserver, Remapping
>>>
>>> prg = Program()
>>> ctl_a = Control()
>>> ctl_a.register_observer(ProgramObserver(prg))
>>>
>>> ctl_a.add('base', [], 'a. {b}. c :- b.')
>>> ctl_a.ground([('base', [])])
>>> print(prg)
a.
__x1.
c :- b.
{b}.
>>>
>>> ctl_b = Control(['0'])
>>> with ctl_b.backend() as backend:
...     mapping = Remapping(backend, prg.output_atoms, prg.facts)
...     prg.add_to_backend(backend, mapping)
...
>>> ctl_b.solve(on_model=print)
a
b c a
```
'''

from typing import (Callable, Iterable, List, Mapping, MutableMapping, MutableSequence, NamedTuple, Optional, Sequence,
                    Tuple, TypeVar)
from dataclasses import dataclass, field
from functools import singledispatch
from itertools import chain
from copy import copy

from clingo import Backend, HeuristicType, Observer, Symbol, TruthValue

__all__ = ['add_to_backend', 'pretty_str', 'remap', 'Edge', 'External', 'Fact',
           'Heuristic', 'Minimize', 'Program', 'ProgramObserver', 'Project',
           'Remapping', 'Rule', 'Show', 'WeightRule']
__pdoc__ = {}

Atom = int
Literal = int
Weight = int
OutputTable = Mapping[Atom, Symbol]
AtomMap = Callable[[Atom], Atom]
Statement = TypeVar('Statement', 'Fact', 'Show', 'Rule', 'WeightRule', 'Heuristic', 'Edge', 'Minimize', 'External',
                    'Project')


@singledispatch
def pretty_str(stm, output_atoms: OutputTable) -> str:  # pylint: disable=unused-argument
    '''
    Pretty print statements.

    Parameters
    ----------
    stm
        The statement to convert to a string.
    output_atoms
        A mapping from program atoms to symbols.

    Returns
    -------
    The string representation of the statement.
    '''
    assert False, 'unexpected type'


@singledispatch
def remap(stm, mapping: AtomMap):  # pylint: disable=unused-argument
    '''
    Remap literals in the given statement with the provided mapping.

    Parameters
    ----------
    stm
        The statement to remap.
    mapping
        The mapping function to remap literals.

    Returns
    -------
    The updated statement.

    See Also
    --------
    Remapping
    '''
    assert False, 'unexpected type'


@singledispatch
def add_to_backend(stm, backend: Backend):  # pylint: disable=unused-argument
    '''
    Add statements to the backend using the provided mapping to map literals.

    Parameters
    ----------
    stm
        The statement to add to the backend.
    backend
        The backend.
    '''
    assert False, 'unexpected type'


def _pretty_str_lit(stm: Literal, output_atoms: OutputTable) -> str:
    '''
    Pretty print literals and atoms.
    '''
    atom = abs(stm)
    if atom in output_atoms:
        atom_str = str(output_atoms[atom])
    else:
        atom_str = f'__x{atom}'

    return f'not {atom_str}' if stm < 0 else atom_str


def _pretty_str_rule_head(choice: bool, has_body: bool, head: Sequence[Atom], output_atoms: OutputTable) -> str:
    '''
    Pretty print the head of a rule including the implication symbol if
    necessary.
    '''
    ret = ''

    if choice:
        ret += '{'
    ret += '; '.join(_pretty_str_lit(lit, output_atoms) for lit in head)
    if choice:
        ret += '}'

    if has_body or (not head and not choice):
        ret += ' :- '

    return ret


def _pretty_str_truth_value(stm: TruthValue):
    '''
    Pretty print a truth value.
    '''
    if stm == TruthValue.False_:
        return 'False'
    if stm == TruthValue.True_:
        return 'True'
    return 'Free'


def _remap_lit(literal: Literal, mapping: AtomMap) -> Atom:
    return -mapping(-literal) if literal < 0 else mapping(literal)


def _remap_seq(literals: Sequence[Literal], mapping: AtomMap):
    '''
    Apply the mapping to a sequence of literals or atoms.
    '''
    return [_remap_lit(lit, mapping) for lit in literals]


def _remap_wseq(literals: Sequence[Tuple[Literal, Weight]], mapping: AtomMap):
    '''
    Apply the mapping to a sequence of weighted literals or atoms.
    '''
    return [(_remap_lit(lit, mapping), weight) for lit, weight in literals]


def _remap_stms(stms: MutableSequence[Statement], mapping: AtomMap):
    '''
    Remap the given statements.
    '''
    for i, stm in enumerate(stms):
        stms[i] = remap(stm, mapping)


def _add_stms_to_backend(stms: Iterable[Statement], backend: Backend, mapping: Optional[AtomMap]):
    '''
    Remap the given statements returning a list with the result.
    '''
    for stm in stms:
        if mapping:
            add_to_backend(remap(stm, mapping), backend)
        else:
            add_to_backend(stm, backend)


class Fact(NamedTuple):
    '''
    Ground representation of a fact.
    '''
    symbol: Symbol


@pretty_str.register(Fact)
def _pretty_str_fact(stm: Fact, output_atoms: OutputTable) -> str:  # pylint: disable=unused-argument
    '''
    Pretty print a fact.
    '''
    return f'{stm.symbol}.'


@remap.register(Fact)
def _remap_fact(stm: Fact, mapping: AtomMap) -> Fact:  # pylint: disable=unused-argument
    '''
    Remap a fact statement.
    '''
    return stm


@add_to_backend.register(Fact)
def _add_to_backend_fact(stm: Fact, backend: Backend) -> None:  # pylint: disable=unused-argument
    '''
    Add a fact to the backend.

    This does nothing to not interfere with the mapping of literals. If facts
    are to be mapped, then this should be done manually beforehand.
    '''


class Show(NamedTuple):
    '''
    Ground representation of a show statements.
    '''
    symbol: Symbol
    condition: Sequence[Literal]


@pretty_str.register(Show)
def _pretty_str_show(stm: Show, output_atoms: OutputTable) -> str:
    '''
    Pretty print a fact.
    '''
    body = ', '.join(_pretty_str_lit(lit, output_atoms) for lit in stm.condition)
    return f'#show {stm.symbol}{": " if body else ""}{body}.'


@remap.register(Show)
def _remap_show(stm: Show, mapping: AtomMap) -> Show:
    '''
    Remap a show statetment.
    '''
    return Show(stm.symbol, _remap_seq(stm.condition, mapping))


@add_to_backend.register(Show)
def _add_to_backend_show(stm: Show, backend: Backend) -> None:  # pylint: disable=unused-argument
    '''
    Add a show statement to the backend.

    Note that this currently does nothing because backend does not yet support
    adding to the symbol table.
    '''


class Rule(NamedTuple):
    '''
    Ground representation of disjunctive and choice rules.
    '''
    choice: bool
    head: Sequence[Atom]
    body: Sequence[Literal]


@pretty_str.register(Rule)
def _pretty_str_rule(stm: Rule, output_atoms: OutputTable) -> str:
    '''
    Pretty print a rule.
    '''
    head = _pretty_str_rule_head(stm.choice, bool(stm.body), stm.head, output_atoms)
    body = ', '.join(_pretty_str_lit(lit, output_atoms) for lit in stm.body)

    return f'{head}{body}.'


@remap.register(Rule)
def _remap_rule(stm: Rule, mapping: AtomMap) -> Rule:
    '''
    Remap literals in a rule.
    '''
    return Rule(stm.choice, _remap_seq(stm.head, mapping), _remap_seq(stm.body, mapping))


@add_to_backend.register(Rule)
def _add_to_backend_rule(stm: Rule, backend: Backend) -> None:
    '''
    Add a rule to the backend.
    '''
    backend.add_rule(stm.head, stm.body, stm.choice)


class WeightRule(NamedTuple):
    '''
    Ground representation of rules with a weight constraint in the body.
    '''
    choice: bool
    head: Sequence[Atom]
    lower_bound: Weight
    body: Sequence[Tuple[Literal, Weight]]


@pretty_str.register(WeightRule)
def _pretty_str_weight_rule(stm: WeightRule, output_atoms: OutputTable) -> str:
    '''
    Pretty print a rule or weight rule.
    '''
    head = _pretty_str_rule_head(stm.choice, bool(stm.body), stm.head, output_atoms)
    body = ', '.join(f'{weight},{i}: {_pretty_str_lit(literal, output_atoms)}'
                     for i, (literal, weight) in enumerate(stm.body))

    return f'{head}{stm.lower_bound}{{{body}}}.'


@remap.register(WeightRule)
def _remap_weight_rule(stm: WeightRule, mapping: AtomMap) -> WeightRule:
    '''
    Remap literals in a weight rule.
    '''
    return WeightRule(stm.choice, _remap_seq(stm.head, mapping), stm.lower_bound, _remap_wseq(stm.body, mapping))


@add_to_backend.register(WeightRule)
def _add_to_backend_weight_rule(stm: WeightRule, backend: Backend) -> None:
    '''
    Add a weight rule to the backend.
    '''
    backend.add_weight_rule(stm.head, stm.lower_bound, stm.body, stm.choice)


class Project(NamedTuple):
    '''
    Ground representation of project statements.
    '''
    atom: Atom


@pretty_str.register(Project)
def _pretty_str_project(stm: Project, output_atoms: OutputTable) -> str:
    '''
    Pretty print a project statement.
    '''
    return f'#project {_pretty_str_lit(stm.atom, output_atoms)}.'


@remap.register(Project)
def _remap_project(stm: Project, mapping: AtomMap):
    '''
    Remap project statement.
    '''
    return Project(mapping(stm.atom))


@add_to_backend.register(Project)
def _add_to_backend_project(stm: Project, backend: Backend):
    '''
    Add a project statement to the backend.
    '''
    backend.add_project([stm.atom])


class External(NamedTuple):
    '''
    Ground representation of external atoms.
    '''
    atom: Atom
    value: TruthValue


@pretty_str.register(External)
def _pretty_print_external(stm: External, output_atoms: OutputTable) -> str:
    '''
    Pretty print an external.
    '''
    return f'#external {_pretty_str_lit(stm.atom, output_atoms)}. [{_pretty_str_truth_value(stm.value)}]'


@remap.register(External)
def _remap_external(stm: External, mapping: AtomMap) -> External:
    '''
    Remap the external.
    '''
    return External(mapping(stm.atom), stm.value)


@add_to_backend.register(External)
def _add_to_backend_external(stm: External, backend: Backend):
    '''
    Add an external statement to the backend remapping its atom.
    '''
    backend.add_external(stm.atom, stm.value)


class Minimize(NamedTuple):
    '''
    Ground representation of a minimize statement.
    '''
    priority: Weight
    literals: Sequence[Tuple[Literal, Weight]]


@pretty_str.register(Minimize)
def _pretty_print_minimize(stm, output_atoms) -> str:
    '''
    Pretty print a minimize statement.
    '''
    body = '; '.join(f'{weight}@{stm.priority},{i}: {_pretty_str_lit(literal, output_atoms)}'
                     for i, (literal, weight) in enumerate(stm.literals))
    return f'#minimize{{{body}}}.'


@remap.register(Minimize)
def _remap_minimize(stm: Minimize, mapping: AtomMap) -> Minimize:
    '''
    Remap the literals in the minimize statement.
    '''
    return Minimize(stm.priority, _remap_wseq(stm.literals, mapping))


@add_to_backend.register(Minimize)
def _add_to_backend_minimize(stm: Minimize, backend: Backend):
    '''
    Add a minimize statement to the backend.
    '''
    backend.add_minimize(stm.priority, stm.literals)


class Heuristic(NamedTuple):
    '''
    Ground representation of a heuristic statement.
    '''
    atom: Atom
    type_: HeuristicType
    bias: Weight
    priority: Weight
    condition: Sequence[Literal]


def _pretty_str_heuristic_type(type_):
    return str(type_).replace('HeuristicType.', '')


@pretty_str.register(Heuristic)
def _pretty_str_heuristic(stm: Heuristic, output_atoms: OutputTable) -> str:
    '''
    Pretty print a heuristic statement.
    '''
    body = ', '.join(_pretty_str_lit(lit, output_atoms) for lit in stm.condition)
    head = _pretty_str_lit(stm.atom, output_atoms)
    type_ = _pretty_str_heuristic_type(stm.type_)
    return f'#heuristic {head}{": " if body else ""}{body}. [{stm.bias}@{stm.priority}, {type_}]'


@remap.register(Heuristic)
def _remap_heuristic(stm: Heuristic, mapping: AtomMap) -> Heuristic:
    '''
    Remap the heuristic statement.
    '''
    return Heuristic(mapping(stm.atom), stm.type_, stm.bias, stm.priority, _remap_seq(stm.condition, mapping))


@add_to_backend.register(Heuristic)
def _add_to_backend_heuristic(stm: Heuristic, backend: Backend) -> None:
    '''
    Add a heurisitic statement to the backend.
    '''
    backend.add_heuristic(stm.atom, stm.type_, stm.bias, stm.priority, stm.condition)


class Edge(NamedTuple):
    '''
    Ground representation of a heuristic statement.
    '''
    u: int
    v: int
    condition: Sequence[Literal]


@pretty_str.register(Edge)
def _pretty_str_edge(stm: Edge, output_atoms: OutputTable) -> str:
    '''
    Pretty print a heuristic statement.
    '''
    body = ', '.join(_pretty_str_lit(lit, output_atoms) for lit in stm.condition)
    return f'#edge ({stm.u},{stm.v}){": " if body else ""}{body}.'


@remap.register(Edge)
def _remap_edge(stm: Edge, mapping: AtomMap) -> Edge:
    '''
    Remap an edge statement.
    '''
    return Edge(stm.u, stm.v, _remap_seq(stm.condition, mapping))


@add_to_backend.register(Edge)
def _add_to_backend_edge(stm: Edge, backend: Backend) -> None:
    '''
    Add an edge statement to the backend remapping its literals.
    '''
    backend.add_acyc_edge(stm.u, stm.v, stm.condition)


@dataclass
class Program:  # pylint: disable=too-many-instance-attributes
    '''
    Ground program representation.

    Although inefficient, the string representation of this program is parsable
    by clingo.
    '''
    output_atoms: MutableMapping[Atom, Symbol] = field(default_factory=dict)
    '''
    A mapping from program atoms to symbols.
    '''
    shows: List[Show] = field(default_factory=list)
    '''
    A list of show statements.
    '''
    facts: List[Fact] = field(default_factory=list)
    '''
    A list of facts.
    '''
    rules: List[Rule] = field(default_factory=list)
    '''
    A list of rules.
    '''
    weight_rules: List[WeightRule] = field(default_factory=list)
    '''
    A list of weight rules.
    '''
    heuristics: List[Heuristic] = field(default_factory=list)
    '''
    A list of heuristic statements.
    '''
    edges: List[Edge] = field(default_factory=list)
    '''
    A list of edge statements.
    '''
    minimizes: List[Minimize] = field(default_factory=list)
    '''
    A list of minimize statements.
    '''
    externals: List[External] = field(default_factory=list)
    '''
    A list of external statements.
    '''
    projects: Optional[List[Project]] = None
    '''
    A list of project statements.
    '''
    assumptions: List[Literal] = field(default_factory=list)
    '''
    A list of assumptions in form of program literals.
    '''

    def _pretty_stms(self, arg: Iterable[Statement], sort: bool) -> Iterable[str]:
        if sort:
            arg = sorted(arg)
        return (pretty_str(x, self.output_atoms) for x in arg)

    def _pretty_assumptions(self, sort: bool) -> Iterable[str]:
        if not self.assumptions:
            return []
        arg = sorted(self.assumptions) if sort else self.assumptions
        assumptions = (_pretty_str_lit(lit, self.output_atoms) for lit in arg)
        return [f'% assumptions: {", ".join(assumptions)}']

    def _pretty_projects(self, sort: bool) -> Iterable[str]:
        if self.projects is None:
            return []
        # This is to inform that there is an empty projection statement.
        # It might be worth to allow writing just #project.
        if not self.projects:
            return ['#project x: #false.']
        arg = sorted(self.projects) if sort else self.projects
        return (pretty_str(project, self.output_atoms) for project in arg)

    def sort(self) -> 'Program':
        '''
        Sort the statements in the program inplace.

        Returns
        -------
        A reference to self.
        '''
        self.shows.sort()
        self.facts.sort()
        self.rules.sort()
        self.weight_rules.sort()
        self.heuristics.sort()
        self.edges.sort()
        self.minimizes.sort()
        self.externals.sort()
        if self.projects is not None:
            self.projects.sort()
        self.assumptions.sort()

        return self

    def remap(self, mapping: AtomMap) -> 'Program':
        '''
        Remap the literals in the program inplace.

        Parameters
        ----------
        mapping
            A function to remap program atoms.

        Returns
        -------
        A reference to self.

        See Also
        --------
        remap
        '''
        _remap_stms(self.shows, mapping)
        _remap_stms(self.facts, mapping)
        _remap_stms(self.rules, mapping)
        _remap_stms(self.weight_rules, mapping)
        _remap_stms(self.heuristics, mapping)
        _remap_stms(self.edges, mapping)
        _remap_stms(self.minimizes, mapping)
        _remap_stms(self.externals, mapping)
        if self.projects is not None:
            _remap_stms(self.projects, mapping)
        for i, lit in enumerate(self.assumptions):
            self.assumptions[i] = _remap_lit(lit, mapping)
        self.output_atoms = {mapping(lit): sym for lit, sym in self.output_atoms.items()}

        return self

    def add_to_backend(self, backend: Backend, mapping: Optional[AtomMap] = None) -> 'Program':
        '''
        Add the program to the given backend with an optional mapping.

        Note that the output table cannot be added to the backend for technical
        reasons. This has to be taken care of by the user. See for example the
        `Remapping` class, which provides functionality for this.

        Parameters
        ----------
        backend
            The backend.
        mapping
            A mapping function to remap literals.

        Returns
        -------
        A reference to self.

        See Also
        --------
        add_to_backend
        '''

        _add_stms_to_backend(self.shows, backend, mapping)
        _add_stms_to_backend(self.facts, backend, mapping)
        _add_stms_to_backend(self.rules, backend, mapping)
        _add_stms_to_backend(self.weight_rules, backend, mapping)
        _add_stms_to_backend(self.heuristics, backend, mapping)
        _add_stms_to_backend(self.edges, backend, mapping)
        _add_stms_to_backend(self.minimizes, backend, mapping)
        _add_stms_to_backend(self.externals, backend, mapping)
        if self.projects is not None:
            if self.projects:
                _add_stms_to_backend(self.projects, backend, mapping)
            else:
                backend.add_project([])

        backend.add_assume([_remap_lit(lit, mapping) if mapping else lit
                            for lit in self.assumptions])

        return self

    def pretty_str(self, sort: bool = True) -> str:
        '''
        Return a readable string represenation of the program.

        Parameters
        ----------
        sort
            Whether to sort the statements in the program befor printing.

        Returns
        -------
        The string representation of the program.
        '''
        return '\n'.join(chain(
            self._pretty_stms(self.shows, sort),
            self._pretty_stms(self.facts, sort),
            self._pretty_stms(self.rules, sort),
            self._pretty_stms(self.weight_rules, sort),
            self._pretty_stms(self.heuristics, sort),
            self._pretty_stms(self.edges, sort),
            self._pretty_stms(self.minimizes, sort),
            self._pretty_stms(self.externals, sort),
            self._pretty_projects(sort),
            self._pretty_assumptions(sort)))

    def copy(self) -> 'Program':
        '''
        Return a shallow copy of the program copying all mutable state.

        Returns
        -------
        A shallow copy of the program.
        '''
        return copy(self)

    def __str__(self) -> str:
        '''
        Return a readable string represenation of the program.
        '''
        return self.pretty_str()


class Remapping:
    '''
    This class maps existing literals to fresh literals as created by the
    backend.

    Parameters
    ----------
    backend
        The backend used to introduce fresh atoms.
    output_atoms
        The output table to initialize the mapping with.
    facts
        A list of facts each of which will receive a fresh program atom.
    '''
    _backend: Backend
    _map: MutableMapping[Atom, Atom]

    def __init__(self, backend: Backend, output_atoms: OutputTable, facts: Iterable[Fact] = None):
        self._backend = backend
        self._map = {}
        for atom, sym in output_atoms.items():
            assert atom not in self._map
            self._map[atom] = self._backend.add_atom(sym)
        if facts is not None:
            for fact in facts:
                backend.add_rule([backend.add_atom(fact.symbol)])

    def __call__(self, atom: Atom) -> Atom:
        '''
        Map the given program atom to the corresponding atom in the backend.

        If the literal was not mapped during initialization, a new literal is
        associated with it.

        Parameters
        ----------
        atom
            The atom to remap.

        Returns
        -------
        The remapped program atom.
        '''
        if atom not in self._map:
            self._map[atom] = self._backend.add_atom()

        return self._map[atom]


__pdoc__['Remapping.__call__'] = True


class ProgramObserver(Observer):
    '''
    Program observer to build a ground program representation while grounding.

    This class explicitly ignores theory atoms because they already have a
    ground representation.

    Parameters
    ----------
    program
        The program to add statements to.
    '''
    _program: Program

    def __init__(self, program: Program):
        self._program = program

    def begin_step(self) -> None:
        '''
        Resets the assumptions.
        '''
        self._program.assumptions.clear()

    def output_atom(self, symbol: Symbol, atom: Atom) -> None:
        '''
        Add the given atom to the list of facts or output table.
        '''
        if atom != 0:
            self._program.output_atoms[atom] = symbol
        else:
            self._program.facts.append(Fact(symbol))

    def output_term(self, symbol: Symbol, condition: Sequence[Literal]) -> None:
        '''
        Add a term to the output table.
        '''
        self._program.shows.append(Show(symbol, condition))

    def rule(self, choice: bool, head: Sequence[Atom], body: Sequence[Literal]) -> None:
        '''
        Add a rule to the ground representation.

        Parameters
        ----------
        choice
            Determines if the head is a choice or a disjunction.
        head
            List of program atoms forming the rule head.
        body
            List of program literals forming the rule body.
        '''
        self._program.rules.append(Rule(choice, head, body))

    def weight_rule(self, choice: bool, head: Sequence[Atom], lower_bound: Weight,
                    body: Sequence[Tuple[Literal, Weight]]) -> None:
        '''
        Add a weight rule to the ground representation.

        Parameters
        ----------
        choice
            Determines if the head is a choice or a disjunction.
        head
            List of program atoms forming the head of the rule.
        lower_bound
            The lower bound of the weight constraint in the rule body.
        body
            List of weighted literals (pairs of literal and weight) forming the
            elements of the weight constraint.
        '''
        self._program.weight_rules.append(WeightRule(choice, head, lower_bound, body))

    def project(self, atoms: Sequence[Atom]) -> None:
        '''
        Add a project statement to the ground representation.

        Parameters
        ----------
        atoms
            The program atoms to project on.
        '''
        if self._program.projects is None:
            self._program.projects = []
        self._program.projects.extend(Project(atom) for atom in atoms)

    def external(self, atom: Atom, value: TruthValue) -> None:
        '''
        Add an external statement to the ground representation.

        Parameters
        ----------
        atom
            The external atom in form of a program literal.
        value
            The truth value of the external statement.
        '''
        self._program.externals.append(External(atom, value))

    def assume(self, literals: Sequence[Literal]) -> None:
        '''
        Extend the program with the given assumptions.

        Parameters
        ----------
        literals
            The program literals to assume (positive literals are true and
            negative literals false for the next solve call).
        '''
        self._program.assumptions.extend(literals)

    def minimize(self, priority: Weight, literals: Sequence[Tuple[Literal, Weight]]) -> None:
        '''
        Add a minimize statement to the ground representation.

        Parameters
        ----------
        priority
            The priority of the directive.
        literals
            List of weighted literals whose sum to minimize (pairs of literal
            and weight).
        '''
        self._program.minimizes.append(Minimize(priority, literals))

    def acyc_edge(self, node_u: int, node_v: int, condition: Sequence[Literal]) -> None:
        '''
        Add an edge statement to the gronud representation.

        Parameters
        ----------
        node_u
            The start vertex of the edge (in form of an integer).
        node_v
            Тhe end vertex of the edge (in form of an integer).
        condition
            The list of program literals forming th condition under which to
            add the edge.
        '''
        self._program.edges.append(Edge(node_u, node_v, condition))

    def heuristic(self, atom: Atom, type_: HeuristicType, bias: Weight, priority: Weight,
                  condition: Sequence[Literal]) -> None:
        '''
        Add heurisitic statement to the gronud representation.

        Parameters
        ----------
        atom
            The program atom heuristically modified.
        type_
            The type of the modification.
        bias
            A signed integer.
        priority
            An unsigned integer.
        condition
            List of program literals.
        '''
        self._program.heuristics.append(Heuristic(atom, type_, bias, priority, condition))

Functions

def add_to_backend(stm, backend: Backend)

Add statements to the backend using the provided mapping to map literals.

Parameters

stm

The statement to add to the backend.

backend

The backend.

Expand source code

@singledispatch
def add_to_backend(stm, backend: Backend):  # pylint: disable=unused-argument
    '''
    Add statements to the backend using the provided mapping to map literals.

    Parameters
    ----------
    stm
        The statement to add to the backend.
    backend
        The backend.
    '''
    assert False, 'unexpected type'

def pretty_str(stm, output_atoms: Mapping[int, Symbol]) ‑> str

Pretty print statements.

Parameters

stm

The statement to convert to a string.

output_atoms

A mapping from program atoms to symbols.

Returns

The string representation of the statement.

Expand source code

@singledispatch
def pretty_str(stm, output_atoms: OutputTable) -> str:  # pylint: disable=unused-argument
    '''
    Pretty print statements.

    Parameters
    ----------
    stm
        The statement to convert to a string.
    output_atoms
        A mapping from program atoms to symbols.

    Returns
    -------
    The string representation of the statement.
    '''
    assert False, 'unexpected type'

def remap(stm, mapping: Callable[[int], int])

Remap literals in the given statement with the provided mapping.

Parameters

stm

The statement to remap.

mapping

The mapping function to remap literals.

Returns

The updated statement.

See Also

Remapping

Expand source code

@singledispatch
def remap(stm, mapping: AtomMap):  # pylint: disable=unused-argument
    '''
    Remap literals in the given statement with the provided mapping.

    Parameters
    ----------
    stm
        The statement to remap.
    mapping
        The mapping function to remap literals.

    Returns
    -------
    The updated statement.

    See Also
    --------
    Remapping
    '''
    assert False, 'unexpected type'

Classes

class Edge (u: int, v: int, condition: Sequence[int])

Ground representation of a heuristic statement.

Expand source code

class Edge(NamedTuple):
    '''
    Ground representation of a heuristic statement.
    '''
    u: int
    v: int
    condition: Sequence[Literal]

Ancestors

• builtins.tuple

Instance variables

var condition : Sequence[int]

Alias for field number 2

var u : int

Alias for field number 0

var v : int

Alias for field number 1

class External (atom: int, value: TruthValue)

Ground representation of external atoms.

Expand source code

class External(NamedTuple):
    '''
    Ground representation of external atoms.
    '''
    atom: Atom
    value: TruthValue

Ancestors

• builtins.tuple

Instance variables

var atom : int

Alias for field number 0

var value : TruthValue

Alias for field number 1

class Fact (symbol: Symbol)

Ground representation of a fact.

Expand source code

class Fact(NamedTuple):
    '''
    Ground representation of a fact.
    '''
    symbol: Symbol

Ancestors

• builtins.tuple

Instance variables

var symbol : Symbol

Alias for field number 0

class Heuristic (atom: int, type_: HeuristicType, bias: int, priority: int, condition: Sequence[int])

Ground representation of a heuristic statement.

Expand source code

class Heuristic(NamedTuple):
    '''
    Ground representation of a heuristic statement.
    '''
    atom: Atom
    type_: HeuristicType
    bias: Weight
    priority: Weight
    condition: Sequence[Literal]

Ancestors

• builtins.tuple

Instance variables

var atom : int

Alias for field number 0

var bias : int

Alias for field number 2

var condition : Sequence[int]

Alias for field number 4

var priority : int

Alias for field number 3

var type_ : HeuristicType

Alias for field number 1

class Minimize (priority: int, literals: Sequence[Tuple[int, int]])

Ground representation of a minimize statement.

Expand source code

class Minimize(NamedTuple):
    '''
    Ground representation of a minimize statement.
    '''
    priority: Weight
    literals: Sequence[Tuple[Literal, Weight]]

Ancestors

• builtins.tuple

Instance variables

var literals : Sequence[Tuple[int, int]]

Alias for field number 1

var priority : int

Alias for field number 0

class Program (output_atoms: MutableMapping[int, Symbol] = <factory>, shows: List[Show] = <factory>, facts: List[Fact] = <factory>, rules: List[Rule] = <factory>, weight_rules: List[WeightRule] = <factory>, heuristics: List[Heuristic] = <factory>, edges: List[Edge] = <factory>, minimizes: List[Minimize] = <factory>, externals: List[External] = <factory>, projects: Optional[List[Project]] = None, assumptions: List[int] = <factory>)

Ground program representation.

Although inefficient, the string representation of this program is parsable by clingo.

Expand source code

class Program:  # pylint: disable=too-many-instance-attributes
    '''
    Ground program representation.

    Although inefficient, the string representation of this program is parsable
    by clingo.
    '''
    output_atoms: MutableMapping[Atom, Symbol] = field(default_factory=dict)
    '''
    A mapping from program atoms to symbols.
    '''
    shows: List[Show] = field(default_factory=list)
    '''
    A list of show statements.
    '''
    facts: List[Fact] = field(default_factory=list)
    '''
    A list of facts.
    '''
    rules: List[Rule] = field(default_factory=list)
    '''
    A list of rules.
    '''
    weight_rules: List[WeightRule] = field(default_factory=list)
    '''
    A list of weight rules.
    '''
    heuristics: List[Heuristic] = field(default_factory=list)
    '''
    A list of heuristic statements.
    '''
    edges: List[Edge] = field(default_factory=list)
    '''
    A list of edge statements.
    '''
    minimizes: List[Minimize] = field(default_factory=list)
    '''
    A list of minimize statements.
    '''
    externals: List[External] = field(default_factory=list)
    '''
    A list of external statements.
    '''
    projects: Optional[List[Project]] = None
    '''
    A list of project statements.
    '''
    assumptions: List[Literal] = field(default_factory=list)
    '''
    A list of assumptions in form of program literals.
    '''

    def _pretty_stms(self, arg: Iterable[Statement], sort: bool) -> Iterable[str]:
        if sort:
            arg = sorted(arg)
        return (pretty_str(x, self.output_atoms) for x in arg)

    def _pretty_assumptions(self, sort: bool) -> Iterable[str]:
        if not self.assumptions:
            return []
        arg = sorted(self.assumptions) if sort else self.assumptions
        assumptions = (_pretty_str_lit(lit, self.output_atoms) for lit in arg)
        return [f'% assumptions: {", ".join(assumptions)}']

    def _pretty_projects(self, sort: bool) -> Iterable[str]:
        if self.projects is None:
            return []
        # This is to inform that there is an empty projection statement.
        # It might be worth to allow writing just #project.
        if not self.projects:
            return ['#project x: #false.']
        arg = sorted(self.projects) if sort else self.projects
        return (pretty_str(project, self.output_atoms) for project in arg)

    def sort(self) -> 'Program':
        '''
        Sort the statements in the program inplace.

        Returns
        -------
        A reference to self.
        '''
        self.shows.sort()
        self.facts.sort()
        self.rules.sort()
        self.weight_rules.sort()
        self.heuristics.sort()
        self.edges.sort()
        self.minimizes.sort()
        self.externals.sort()
        if self.projects is not None:
            self.projects.sort()
        self.assumptions.sort()

        return self

    def remap(self, mapping: AtomMap) -> 'Program':
        '''
        Remap the literals in the program inplace.

        Parameters
        ----------
        mapping
            A function to remap program atoms.

        Returns
        -------
        A reference to self.

        See Also
        --------
        remap
        '''
        _remap_stms(self.shows, mapping)
        _remap_stms(self.facts, mapping)
        _remap_stms(self.rules, mapping)
        _remap_stms(self.weight_rules, mapping)
        _remap_stms(self.heuristics, mapping)
        _remap_stms(self.edges, mapping)
        _remap_stms(self.minimizes, mapping)
        _remap_stms(self.externals, mapping)
        if self.projects is not None:
            _remap_stms(self.projects, mapping)
        for i, lit in enumerate(self.assumptions):
            self.assumptions[i] = _remap_lit(lit, mapping)
        self.output_atoms = {mapping(lit): sym for lit, sym in self.output_atoms.items()}

        return self

    def add_to_backend(self, backend: Backend, mapping: Optional[AtomMap] = None) -> 'Program':
        '''
        Add the program to the given backend with an optional mapping.

        Note that the output table cannot be added to the backend for technical
        reasons. This has to be taken care of by the user. See for example the
        `Remapping` class, which provides functionality for this.

        Parameters
        ----------
        backend
            The backend.
        mapping
            A mapping function to remap literals.

        Returns
        -------
        A reference to self.

        See Also
        --------
        add_to_backend
        '''

        _add_stms_to_backend(self.shows, backend, mapping)
        _add_stms_to_backend(self.facts, backend, mapping)
        _add_stms_to_backend(self.rules, backend, mapping)
        _add_stms_to_backend(self.weight_rules, backend, mapping)
        _add_stms_to_backend(self.heuristics, backend, mapping)
        _add_stms_to_backend(self.edges, backend, mapping)
        _add_stms_to_backend(self.minimizes, backend, mapping)
        _add_stms_to_backend(self.externals, backend, mapping)
        if self.projects is not None:
            if self.projects:
                _add_stms_to_backend(self.projects, backend, mapping)
            else:
                backend.add_project([])

        backend.add_assume([_remap_lit(lit, mapping) if mapping else lit
                            for lit in self.assumptions])

        return self

    def pretty_str(self, sort: bool = True) -> str:
        '''
        Return a readable string represenation of the program.

        Parameters
        ----------
        sort
            Whether to sort the statements in the program befor printing.

        Returns
        -------
        The string representation of the program.
        '''
        return '\n'.join(chain(
            self._pretty_stms(self.shows, sort),
            self._pretty_stms(self.facts, sort),
            self._pretty_stms(self.rules, sort),
            self._pretty_stms(self.weight_rules, sort),
            self._pretty_stms(self.heuristics, sort),
            self._pretty_stms(self.edges, sort),
            self._pretty_stms(self.minimizes, sort),
            self._pretty_stms(self.externals, sort),
            self._pretty_projects(sort),
            self._pretty_assumptions(sort)))

    def copy(self) -> 'Program':
        '''
        Return a shallow copy of the program copying all mutable state.

        Returns
        -------
        A shallow copy of the program.
        '''
        return copy(self)

    def __str__(self) -> str:
        '''
        Return a readable string represenation of the program.
        '''
        return self.pretty_str()

Class variables

var assumptions : List[int]

A list of assumptions in form of program literals.

var edges : List[Edge]

A list of edge statements.

var externals : List[External]

A list of external statements.

var facts : List[Fact]

A list of facts.

var heuristics : List[Heuristic]

A list of heuristic statements.

var minimizes : List[Minimize]

A list of minimize statements.

var output_atoms : MutableMapping[int, Symbol]

A mapping from program atoms to symbols.

var projects : Optional[List[Project]]

A list of project statements.

var rules : List[Rule]

A list of rules.

var shows : List[Show]

A list of show statements.

var weight_rules : List[WeightRule]

A list of weight rules.

Methods

def add_to_backend(self, backend: Backend, mapping: Optional[Callable[[int], int]] = None) ‑> Program

Add the program to the given backend with an optional mapping.

Note that the output table cannot be added to the backend for technical reasons. This has to be taken care of by the user. See for example the Remapping class, which provides functionality for this.

Parameters

backend

The backend.

mapping

A mapping function to remap literals.

Returns

A reference to self.

See Also

add_to_backend()

Expand source code

def add_to_backend(self, backend: Backend, mapping: Optional[AtomMap] = None) -> 'Program':
    '''
    Add the program to the given backend with an optional mapping.

    Note that the output table cannot be added to the backend for technical
    reasons. This has to be taken care of by the user. See for example the
    `Remapping` class, which provides functionality for this.

    Parameters
    ----------
    backend
        The backend.
    mapping
        A mapping function to remap literals.

    Returns
    -------
    A reference to self.

    See Also
    --------
    add_to_backend
    '''

    _add_stms_to_backend(self.shows, backend, mapping)
    _add_stms_to_backend(self.facts, backend, mapping)
    _add_stms_to_backend(self.rules, backend, mapping)
    _add_stms_to_backend(self.weight_rules, backend, mapping)
    _add_stms_to_backend(self.heuristics, backend, mapping)
    _add_stms_to_backend(self.edges, backend, mapping)
    _add_stms_to_backend(self.minimizes, backend, mapping)
    _add_stms_to_backend(self.externals, backend, mapping)
    if self.projects is not None:
        if self.projects:
            _add_stms_to_backend(self.projects, backend, mapping)
        else:
            backend.add_project([])

    backend.add_assume([_remap_lit(lit, mapping) if mapping else lit
                        for lit in self.assumptions])

    return self

def copy(self) ‑> Program

Return a shallow copy of the program copying all mutable state.

Returns

A shallow copy of the program.

Expand source code

def copy(self) -> 'Program':
    '''
    Return a shallow copy of the program copying all mutable state.

    Returns
    -------
    A shallow copy of the program.
    '''
    return copy(self)

def pretty_str(self, sort: bool = True) ‑> str

Return a readable string represenation of the program.

Parameters

sort

Whether to sort the statements in the program befor printing.

Returns

The string representation of the program.

Expand source code

def pretty_str(self, sort: bool = True) -> str:
    '''
    Return a readable string represenation of the program.

    Parameters
    ----------
    sort
        Whether to sort the statements in the program befor printing.

    Returns
    -------
    The string representation of the program.
    '''
    return '\n'.join(chain(
        self._pretty_stms(self.shows, sort),
        self._pretty_stms(self.facts, sort),
        self._pretty_stms(self.rules, sort),
        self._pretty_stms(self.weight_rules, sort),
        self._pretty_stms(self.heuristics, sort),
        self._pretty_stms(self.edges, sort),
        self._pretty_stms(self.minimizes, sort),
        self._pretty_stms(self.externals, sort),
        self._pretty_projects(sort),
        self._pretty_assumptions(sort)))

def remap(self, mapping: Callable[[int], int]) ‑> Program

Remap the literals in the program inplace.

Parameters

mapping

A function to remap program atoms.

Returns

A reference to self.

See Also

remap()

Expand source code

def remap(self, mapping: AtomMap) -> 'Program':
    '''
    Remap the literals in the program inplace.

    Parameters
    ----------
    mapping
        A function to remap program atoms.

    Returns
    -------
    A reference to self.

    See Also
    --------
    remap
    '''
    _remap_stms(self.shows, mapping)
    _remap_stms(self.facts, mapping)
    _remap_stms(self.rules, mapping)
    _remap_stms(self.weight_rules, mapping)
    _remap_stms(self.heuristics, mapping)
    _remap_stms(self.edges, mapping)
    _remap_stms(self.minimizes, mapping)
    _remap_stms(self.externals, mapping)
    if self.projects is not None:
        _remap_stms(self.projects, mapping)
    for i, lit in enumerate(self.assumptions):
        self.assumptions[i] = _remap_lit(lit, mapping)
    self.output_atoms = {mapping(lit): sym for lit, sym in self.output_atoms.items()}

    return self

def sort(self) ‑> Program

Sort the statements in the program inplace.

Returns

A reference to self.

Expand source code

def sort(self) -> 'Program':
    '''
    Sort the statements in the program inplace.

    Returns
    -------
    A reference to self.
    '''
    self.shows.sort()
    self.facts.sort()
    self.rules.sort()
    self.weight_rules.sort()
    self.heuristics.sort()
    self.edges.sort()
    self.minimizes.sort()
    self.externals.sort()
    if self.projects is not None:
        self.projects.sort()
    self.assumptions.sort()

    return self

class ProgramObserver (program: Program)

Program observer to build a ground program representation while grounding.

This class explicitly ignores theory atoms because they already have a ground representation.

Parameters

program

The program to add statements to.

Expand source code

class ProgramObserver(Observer):
    '''
    Program observer to build a ground program representation while grounding.

    This class explicitly ignores theory atoms because they already have a
    ground representation.

    Parameters
    ----------
    program
        The program to add statements to.
    '''
    _program: Program

    def __init__(self, program: Program):
        self._program = program

    def begin_step(self) -> None:
        '''
        Resets the assumptions.
        '''
        self._program.assumptions.clear()

    def output_atom(self, symbol: Symbol, atom: Atom) -> None:
        '''
        Add the given atom to the list of facts or output table.
        '''
        if atom != 0:
            self._program.output_atoms[atom] = symbol
        else:
            self._program.facts.append(Fact(symbol))

    def output_term(self, symbol: Symbol, condition: Sequence[Literal]) -> None:
        '''
        Add a term to the output table.
        '''
        self._program.shows.append(Show(symbol, condition))

    def rule(self, choice: bool, head: Sequence[Atom], body: Sequence[Literal]) -> None:
        '''
        Add a rule to the ground representation.

        Parameters
        ----------
        choice
            Determines if the head is a choice or a disjunction.
        head
            List of program atoms forming the rule head.
        body
            List of program literals forming the rule body.
        '''
        self._program.rules.append(Rule(choice, head, body))

    def weight_rule(self, choice: bool, head: Sequence[Atom], lower_bound: Weight,
                    body: Sequence[Tuple[Literal, Weight]]) -> None:
        '''
        Add a weight rule to the ground representation.

        Parameters
        ----------
        choice
            Determines if the head is a choice or a disjunction.
        head
            List of program atoms forming the head of the rule.
        lower_bound
            The lower bound of the weight constraint in the rule body.
        body
            List of weighted literals (pairs of literal and weight) forming the
            elements of the weight constraint.
        '''
        self._program.weight_rules.append(WeightRule(choice, head, lower_bound, body))

    def project(self, atoms: Sequence[Atom]) -> None:
        '''
        Add a project statement to the ground representation.

        Parameters
        ----------
        atoms
            The program atoms to project on.
        '''
        if self._program.projects is None:
            self._program.projects = []
        self._program.projects.extend(Project(atom) for atom in atoms)

    def external(self, atom: Atom, value: TruthValue) -> None:
        '''
        Add an external statement to the ground representation.

        Parameters
        ----------
        atom
            The external atom in form of a program literal.
        value
            The truth value of the external statement.
        '''
        self._program.externals.append(External(atom, value))

    def assume(self, literals: Sequence[Literal]) -> None:
        '''
        Extend the program with the given assumptions.

        Parameters
        ----------
        literals
            The program literals to assume (positive literals are true and
            negative literals false for the next solve call).
        '''
        self._program.assumptions.extend(literals)

    def minimize(self, priority: Weight, literals: Sequence[Tuple[Literal, Weight]]) -> None:
        '''
        Add a minimize statement to the ground representation.

        Parameters
        ----------
        priority
            The priority of the directive.
        literals
            List of weighted literals whose sum to minimize (pairs of literal
            and weight).
        '''
        self._program.minimizes.append(Minimize(priority, literals))

    def acyc_edge(self, node_u: int, node_v: int, condition: Sequence[Literal]) -> None:
        '''
        Add an edge statement to the gronud representation.

        Parameters
        ----------
        node_u
            The start vertex of the edge (in form of an integer).
        node_v
            Тhe end vertex of the edge (in form of an integer).
        condition
            The list of program literals forming th condition under which to
            add the edge.
        '''
        self._program.edges.append(Edge(node_u, node_v, condition))

    def heuristic(self, atom: Atom, type_: HeuristicType, bias: Weight, priority: Weight,
                  condition: Sequence[Literal]) -> None:
        '''
        Add heurisitic statement to the gronud representation.

        Parameters
        ----------
        atom
            The program atom heuristically modified.
        type_
            The type of the modification.
        bias
            A signed integer.
        priority
            An unsigned integer.
        condition
            List of program literals.
        '''
        self._program.heuristics.append(Heuristic(atom, type_, bias, priority, condition))

Ancestors

• Observer

Methods

def acyc_edge(self, node_u: int, node_v: int, condition: Sequence[int]) ‑> None

Add an edge statement to the gronud representation.

Parameters

node_u

The start vertex of the edge (in form of an integer).

node_v

Тhe end vertex of the edge (in form of an integer).

condition

The list of program literals forming th condition under which to add the edge.

Expand source code

def acyc_edge(self, node_u: int, node_v: int, condition: Sequence[Literal]) -> None:
    '''
    Add an edge statement to the gronud representation.

    Parameters
    ----------
    node_u
        The start vertex of the edge (in form of an integer).
    node_v
        Тhe end vertex of the edge (in form of an integer).
    condition
        The list of program literals forming th condition under which to
        add the edge.
    '''
    self._program.edges.append(Edge(node_u, node_v, condition))

def assume(self, literals: Sequence[int]) ‑> None

Extend the program with the given assumptions.

Parameters

literals

The program literals to assume (positive literals are true and negative literals false for the next solve call).

Expand source code

def assume(self, literals: Sequence[Literal]) -> None:
    '''
    Extend the program with the given assumptions.

    Parameters
    ----------
    literals
        The program literals to assume (positive literals are true and
        negative literals false for the next solve call).
    '''
    self._program.assumptions.extend(literals)

def begin_step(self) ‑> None

Resets the assumptions.

Expand source code

def begin_step(self) -> None:
    '''
    Resets the assumptions.
    '''
    self._program.assumptions.clear()

def external(self, atom: int, value: TruthValue) ‑> None

Add an external statement to the ground representation.

Parameters

atom

The external atom in form of a program literal.

value

The truth value of the external statement.

Expand source code

def external(self, atom: Atom, value: TruthValue) -> None:
    '''
    Add an external statement to the ground representation.

    Parameters
    ----------
    atom
        The external atom in form of a program literal.
    value
        The truth value of the external statement.
    '''
    self._program.externals.append(External(atom, value))

def heuristic(self, atom: int, type_: HeuristicType, bias: int, priority: int, condition: Sequence[int]) ‑> None

Add heurisitic statement to the gronud representation.

Parameters

atom

The program atom heuristically modified.

type_

The type of the modification.

bias

A signed integer.

priority

An unsigned integer.

condition

List of program literals.

Expand source code

def heuristic(self, atom: Atom, type_: HeuristicType, bias: Weight, priority: Weight,
              condition: Sequence[Literal]) -> None:
    '''
    Add heurisitic statement to the gronud representation.

    Parameters
    ----------
    atom
        The program atom heuristically modified.
    type_
        The type of the modification.
    bias
        A signed integer.
    priority
        An unsigned integer.
    condition
        List of program literals.
    '''
    self._program.heuristics.append(Heuristic(atom, type_, bias, priority, condition))

def minimize(self, priority: int, literals: Sequence[Tuple[int, int]]) ‑> None

Add a minimize statement to the ground representation.

Parameters

priority

The priority of the directive.

literals

List of weighted literals whose sum to minimize (pairs of literal and weight).

Expand source code

def minimize(self, priority: Weight, literals: Sequence[Tuple[Literal, Weight]]) -> None:
    '''
    Add a minimize statement to the ground representation.

    Parameters
    ----------
    priority
        The priority of the directive.
    literals
        List of weighted literals whose sum to minimize (pairs of literal
        and weight).
    '''
    self._program.minimizes.append(Minimize(priority, literals))

def output_atom(self, symbol: Symbol, atom: int) ‑> None

Add the given atom to the list of facts or output table.

Expand source code

def output_atom(self, symbol: Symbol, atom: Atom) -> None:
    '''
    Add the given atom to the list of facts or output table.
    '''
    if atom != 0:
        self._program.output_atoms[atom] = symbol
    else:
        self._program.facts.append(Fact(symbol))

def output_term(self, symbol: Symbol, condition: Sequence[int]) ‑> None

Add a term to the output table.

Expand source code

def output_term(self, symbol: Symbol, condition: Sequence[Literal]) -> None:
    '''
    Add a term to the output table.
    '''
    self._program.shows.append(Show(symbol, condition))

def project(self, atoms: Sequence[int]) ‑> None

Add a project statement to the ground representation.

Parameters

atoms

The program atoms to project on.

Expand source code

def project(self, atoms: Sequence[Atom]) -> None:
    '''
    Add a project statement to the ground representation.

    Parameters
    ----------
    atoms
        The program atoms to project on.
    '''
    if self._program.projects is None:
        self._program.projects = []
    self._program.projects.extend(Project(atom) for atom in atoms)

def rule(self, choice: bool, head: Sequence[int], body: Sequence[int]) ‑> None

Add a rule to the ground representation.

Parameters

choice

Determines if the head is a choice or a disjunction.

head

List of program atoms forming the rule head.

body

List of program literals forming the rule body.

Expand source code

def rule(self, choice: bool, head: Sequence[Atom], body: Sequence[Literal]) -> None:
    '''
    Add a rule to the ground representation.

    Parameters
    ----------
    choice
        Determines if the head is a choice or a disjunction.
    head
        List of program atoms forming the rule head.
    body
        List of program literals forming the rule body.
    '''
    self._program.rules.append(Rule(choice, head, body))

def weight_rule(self, choice: bool, head: Sequence[int], lower_bound: int, body: Sequence[Tuple[int, int]]) ‑> None

Add a weight rule to the ground representation.

Parameters

choice

Determines if the head is a choice or a disjunction.

head

List of program atoms forming the head of the rule.

lower_bound

The lower bound of the weight constraint in the rule body.

body

List of weighted literals (pairs of literal and weight) forming the elements of the weight constraint.

Expand source code

def weight_rule(self, choice: bool, head: Sequence[Atom], lower_bound: Weight,
                body: Sequence[Tuple[Literal, Weight]]) -> None:
    '''
    Add a weight rule to the ground representation.

    Parameters
    ----------
    choice
        Determines if the head is a choice or a disjunction.
    head
        List of program atoms forming the head of the rule.
    lower_bound
        The lower bound of the weight constraint in the rule body.
    body
        List of weighted literals (pairs of literal and weight) forming the
        elements of the weight constraint.
    '''
    self._program.weight_rules.append(WeightRule(choice, head, lower_bound, body))

Inherited members

• Observer:
  • end_step
  • init_program
  • output_csp
  • theory_atom
  • theory_atom_with_guard
  • theory_element
  • theory_term_compound
  • theory_term_number
  • theory_term_string

class Project (atom: int)

Ground representation of project statements.

Expand source code

class Project(NamedTuple):
    '''
    Ground representation of project statements.
    '''
    atom: Atom

Ancestors

• builtins.tuple

Instance variables

var atom : int

Alias for field number 0

class Remapping (backend: Backend, output_atoms: Mapping[int, Symbol], facts: Iterable[Fact] = None)

This class maps existing literals to fresh literals as created by the backend.

Parameters

backend

The backend used to introduce fresh atoms.

output_atoms

The output table to initialize the mapping with.

facts

A list of facts each of which will receive a fresh program atom.

Expand source code

class Remapping:
    '''
    This class maps existing literals to fresh literals as created by the
    backend.

    Parameters
    ----------
    backend
        The backend used to introduce fresh atoms.
    output_atoms
        The output table to initialize the mapping with.
    facts
        A list of facts each of which will receive a fresh program atom.
    '''
    _backend: Backend
    _map: MutableMapping[Atom, Atom]

    def __init__(self, backend: Backend, output_atoms: OutputTable, facts: Iterable[Fact] = None):
        self._backend = backend
        self._map = {}
        for atom, sym in output_atoms.items():
            assert atom not in self._map
            self._map[atom] = self._backend.add_atom(sym)
        if facts is not None:
            for fact in facts:
                backend.add_rule([backend.add_atom(fact.symbol)])

    def __call__(self, atom: Atom) -> Atom:
        '''
        Map the given program atom to the corresponding atom in the backend.

        If the literal was not mapped during initialization, a new literal is
        associated with it.

        Parameters
        ----------
        atom
            The atom to remap.

        Returns
        -------
        The remapped program atom.
        '''
        if atom not in self._map:
            self._map[atom] = self._backend.add_atom()

        return self._map[atom]

Methods

def __call__(self, atom: int) ‑> int

Map the given program atom to the corresponding atom in the backend.

If the literal was not mapped during initialization, a new literal is associated with it.

Parameters

atom

The atom to remap.

Returns

The remapped program atom.

Expand source code

def __call__(self, atom: Atom) -> Atom:
    '''
    Map the given program atom to the corresponding atom in the backend.

    If the literal was not mapped during initialization, a new literal is
    associated with it.

    Parameters
    ----------
    atom
        The atom to remap.

    Returns
    -------
    The remapped program atom.
    '''
    if atom not in self._map:
        self._map[atom] = self._backend.add_atom()

    return self._map[atom]

class Rule (choice: bool, head: Sequence[int], body: Sequence[int])

Ground representation of disjunctive and choice rules.

Expand source code

class Rule(NamedTuple):
    '''
    Ground representation of disjunctive and choice rules.
    '''
    choice: bool
    head: Sequence[Atom]
    body: Sequence[Literal]

Ancestors

• builtins.tuple

Instance variables

var body : Sequence[int]

Alias for field number 2

var choice : bool

Alias for field number 0

var head : Sequence[int]

Alias for field number 1

class Show (symbol: Symbol, condition: Sequence[int])

Ground representation of a show statements.

Expand source code

class Show(NamedTuple):
    '''
    Ground representation of a show statements.
    '''
    symbol: Symbol
    condition: Sequence[Literal]

Ancestors

• builtins.tuple

Instance variables

var condition : Sequence[int]

Alias for field number 1

var symbol : Symbol

Alias for field number 0

class WeightRule (choice: bool, head: Sequence[int], lower_bound: int, body: Sequence[Tuple[int, int]])

Ground representation of rules with a weight constraint in the body.

Expand source code

class WeightRule(NamedTuple):
    '''
    Ground representation of rules with a weight constraint in the body.
    '''
    choice: bool
    head: Sequence[Atom]
    lower_bound: Weight
    body: Sequence[Tuple[Literal, Weight]]

Ancestors

• builtins.tuple

Instance variables

var body : Sequence[Tuple[int, int]]

Alias for field number 3

var choice : bool

Alias for field number 0

var head : Sequence[int]

Alias for field number 1

var lower_bound : int

Alias for field number 2