.. _cpp-rule/Composer:

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rule/Composer.hpp
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.. default-domain:: cpp
.. default-role:: cpp:texpr

.. py:currentmodule:: mod
.. cpp:namespace:: mod

.. class:: rule::Composer

    This class can evaluate rule composition expressions. During evaluation an expression graph is recorded.

    The expression graph is a directed hypergraph :math:`(V, E)`, with each vertex representing a rule.
    Each edge represent all compositions calculated for a unique input. That is every edge :math:`e\in E` is on the form
    :math:`((u, v), R_e)` with :math:`(u, v)\in V\times V` as an *ordered* pair of rules and :math:`R_e\subseteq V` is the set
    of all resulting rules found.

    The graph is visualized as a bipartite graph with point-shaped vertices representing the hyperedges. The in-edges to these
    hyperedge vertices are labelled with 1 and 2.

    .. function:: Composer(const std::unordered_set<std::shared_ptr<Rule>> &database, LabelSettings labelSettings)

        .. note:: The caller is responsible for ensuring the given rules are unique.
    .. function:: Composer(Composer &&) = delete
    .. function:: Composer &operator=(Composer &&) = delete
    .. function:: const std::unordered_set<std::shared_ptr<Rule>> &getRuleDatabase() const

        :returns: the set of unique rules known by the evaluator.
    .. function:: const std::unordered_set<std::shared_ptr<Rule>> &getCreatedRules() const

        :returns: the set of unique rules this evaluator has constructed.
    .. function:: std::vector<std::shared_ptr<Rule>> eval(const RCExp::Expression &exp, bool onlyUnique, int verbosity)

        Evaluates a rule composition expression.
        Any created rule is replaced by a rule in the database if they are isomorphic.

        The `onlyUnique` parameter controls whether each composition (sub-)result may contain duplicates or not.
        Unless you need to count possibilities, prefer passing `true` to avoid accidental combinatorial explosion.

        The :var:`verbosity` has the following meaning:

        - 0 (or less): no information is printed.
        - 10: print information about morphism generation for rule composition.
        - 20: print rule composition information.

        :returns: the result of the expression.
    .. function:: void print() const

        Print the graph representing all expressions evaluated so far.