Started implementing support for #show statements.

include/anthem/AST.h

@@ -201,7 +201,6 @@ struct Interval
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-// TODO: implement declaration/signature
 struct Predicate
 {
 	explicit Predicate(std::string &&name)
@@ -231,6 +230,26 @@ struct Predicate
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
+// TODO: make more use of this class
+struct PredicateSignature
+{
+	explicit PredicateSignature(std::string &&name, size_t arity)
+	:	name{std::move(name)},
+		arity{arity}
+	{
+	}
+
+	PredicateSignature(const PredicateSignature &other) = delete;
+	PredicateSignature &operator=(const PredicateSignature &other) = delete;
+	PredicateSignature(PredicateSignature &&other) noexcept = default;
+	PredicateSignature &operator=(PredicateSignature &&other) noexcept = default;
+
+	std::string name;
+	size_t arity;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
 struct SpecialInteger
 {
 	enum class Type

include/anthem/Context.h

@@ -1,6 +1,9 @@
 #ifndef __ANTHEM__CONTEXT_H
 #define __ANTHEM__CONTEXT_H
 
+#include <experimental/optional>
+
+#include <anthem/AST.h>
 #include <anthem/output/Logger.h>
 
 namespace anthem
@@ -25,6 +28,8 @@ struct Context
 
 	bool simplify = false;
 	bool complete = false;
+
+	std::experimental::optional<std::vector<ast::PredicateSignature>> visiblePredicateSignatures;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////

include/anthem/StatementVisitor.h

@@ -150,10 +150,36 @@ struct StatementVisitor
 		}
 	}
 
+	void visit(const Clingo::AST::ShowSignature &showSignature, const Clingo::AST::Statement &statement, std::vector<ast::ScopedFormula> &, Context &context)
+	{
+		if (showSignature.csp)
+			throw LogicException(statement.location, "CSP #show statements are not supported");
+
+		auto &signature = showSignature.signature;
+
+		if (signature.negative())
+			throw LogicException(statement.location, "negative #show atom signatures are currently unsupported");
+
+		if (!context.visiblePredicateSignatures)
+			context.visiblePredicateSignatures.emplace();
+
+		if (std::strlen(signature.name()) == 0)
+			return;
+
+		context.logger.log(output::Priority::Debug) << "showing “" << signature.name() << "/" << signature.arity() << "”";
+
+		context.visiblePredicateSignatures.value().emplace_back(std::string(signature.name()), signature.arity());
+	}
+
+	void visit(const Clingo::AST::ShowTerm &, const Clingo::AST::Statement &statement, std::vector<ast::ScopedFormula> &, Context &)
+	{
+		throw LogicException(statement.location, "only #show statements for atoms (not terms) are supported currently");
+	}
+
 	template<class T>
 	void visit(const T &, const Clingo::AST::Statement &statement, std::vector<ast::ScopedFormula> &, Context &)
 	{
-		throw LogicException(statement.location, "statement currently unsupported, expected rule");
+		throw LogicException(statement.location, "statement currently unsupported");
 	}
 };
 

src/anthem/Translation.cpp

@@ -64,6 +64,8 @@ void translate(const char *fileName, std::istream &stream, Context &context)
 
 	ast::PrintContext printContext;
 
+	// TODO: respect predicate visibility in output
+
 	if (!context.complete)
 	{
 		for (const auto &scopedFormula : scopedFormulas)