souffle::ast::transform::ReplaceSingletonVariablesTransformer Class Reference

Transformation pass to replace singleton variables with unnamed variables. More...

#include <ReplaceSingletonVariables.h>

Inheritance diagram for souffle::ast::transform::ReplaceSingletonVariablesTransformer:

Collaboration diagram for souffle::ast::transform::ReplaceSingletonVariablesTransformer:

Public Member Functions
ReplaceSingletonVariablesTransformer *	clone () const override
std::string	getName () const override
Public Member Functions inherited from souffle::ast::transform::Transformer
bool	apply (TranslationUnit &translationUnit)
virtual	~Transformer ()=default

Private Member Functions
bool	transform (TranslationUnit &translationUnit) override

Detailed Description

Transformation pass to replace singleton variables with unnamed variables.

E.g.: a() :- b(x). -> a() :- b(_).

Definition at line 32 of file ReplaceSingletonVariables.h.

Member Function Documentation

clone()

ReplaceSingletonVariablesTransformer* souffle::ast::transform::ReplaceSingletonVariablesTransformer::clone ( ) const

inlineoverridevirtual

Implements souffle::ast::transform::Transformer.

Definition at line 42 of file ReplaceSingletonVariables.h.

getName()

std::string souffle::ast::transform::ReplaceSingletonVariablesTransformer::getName ( ) const

inlineoverridevirtual

Implements souffle::ast::transform::Transformer.

Definition at line 38 of file ReplaceSingletonVariables.h.

       :
    bool transform(TranslationUnit& translationUnit) override;
};

transform()

bool souffle::ast::transform::ReplaceSingletonVariablesTransformer::transform ( TranslationUnit &  translationUnit )

overrideprivatevirtual

Implements souffle::ast::transform::Transformer.

Definition at line 38 of file ReplaceSingletonVariables.cpp.

                             : public NodeMapper {
        std::set<std::string>& singletons;
 
        replaceSingletons(std::set<std::string>& singletons) : singletons(singletons) {}
 
        Own<Node> operator()(Own<Node> node) const override {
            if (auto* var = dynamic_cast<ast::Variable*>(node.get())) {
                if (singletons.find(var->getName()) != singletons.end()) {
                    return mk<UnnamedVariable>();
                }
            }
            node->apply(*this);
            return node;
        }
    };
 
    for (Relation* rel : program.getRelations()) {
        for (Clause* clause : getClauses(program, *rel)) {
            std::set<std::string> nonsingletons;
            std::set<std::string> vars;
 
            visitDepthFirst(*clause, [&](const ast::Variable& var) {
                const std::string& name = var.getName();
                if (vars.find(name) != vars.end()) {
                    // Variable seen before, so not a singleton variable
                    nonsingletons.insert(name);
                } else {
                    vars.insert(name);
                }
            });
 
            std::set<std::string> ignoredVars;
 
            // Don't unname singleton variables occurring in records.
            // TODO (azreika): remove this check once issue #420 is fixed
            std::set<std::string> recordVars;
            visitDepthFirst(*clause, [&](const RecordInit& rec) {
                visitDepthFirst(rec, [&](const ast::Variable& var) { ignoredVars.insert(var.getName()); });
            });
 
            // Don't unname singleton variables occuring in constraints.
            std::set<std::string> constraintVars;
            visitDepthFirst(*clause, [&](const Constraint& cons) {
                visitDepthFirst(cons, [&](const ast::Variable& var) { ignoredVars.insert(var.getName()); });
            });
 
            std::set<std::string> singletons;
            for (auto& var : vars) {
                if ((nonsingletons.find(var) == nonsingletons.end()) &&
                        (ignoredVars.find(var) == ignoredVars.end())) {
                    changed = true;
                    singletons.insert(var);
                }
            }
 
            // Replace the singletons found with underscores
            replaceSingletons update(singletons);
            clause->apply(update);
        }
    }
 
    return changed;
}
 
}  // namespace souffle::ast::transform

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The documentation for this class was generated from the following files:

• ast/transform/ReplaceSingletonVariables.h
• ast/transform/ReplaceSingletonVariables.cpp