2.2.10.1. rule/Composer.h

2.2.10.1.1. Class rule::Composer

class rule::Composer

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

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

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

2.2.10.1.1.1. Synopsis

class Composer {
    Composer(const std::unordered_set<std::shared_ptr<Rule> > &database, LabelSettings labelSettings);
    Composer(const Composer&) = delete;
    Composer &operator=(const Composer&) = delete;
    Composer(Composer&&) = delete;
    Composer &operator=(Composer&&) = delete;
public:
    ~Composer();
    const std::unordered_set<std::shared_ptr<Rule> > &getRuleDatabase() const;
    const std::unordered_set<std::shared_ptr<Rule> > &getProducts() const;
    std::unordered_set<std::shared_ptr<Rule> > eval(const RCExp::Expression &exp);
    void print() const;
private:
    struct Pimpl;
    std::unique_ptr<Pimpl> p;
public:
    static std::shared_ptr<Composer> create(const std::unordered_set<std::shared_ptr<Rule> > &database, LabelSettings labelSettings);
};

2.2.10.1.1.2. Details

const std::unordered_set<std::shared_ptr<Rule>> &getRuleDatabase() const
Returns:the set of unique rules known by the evaluator.
const std::unordered_set<std::shared_ptr<Rule>> &getProducts() const
Returns:the set of unique rules this evaluator has constructed.
std::unordered_set<std::shared_ptr<Rule>> eval(const RCExp::Expression &exp)

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

Returns:the result of the expression.
void print() const

Print the graph representing all expressions evaluated so far.

static std::shared_ptr<Composer> create(const std::unordered_set<std::shared_ptr<Rule>> &database, LabelSettings labelSettings)
Returns:a new instance of an evaluator with its database initialised with the given rules.

Note

The caller is responsible for ensuring the given rules are unique.