From eaabeb0c55e524f9b3d874d5df625906248fa03a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrick=20L=C3=BChne?= <patrick@luehne.de>
Date: Mon, 9 Apr 2018 00:07:47 +0200
Subject: [PATCH] Support exponentiation operator

Because of a bug in the Clingo API, the exponentation operator was not
properly exposed to anthem. This updates Clingo to a version with a
fixed API and adds proper support for exponentation within anthem along
with a matching unit test.
---
 include/anthem/AST.h        |  3 ++-
 include/anthem/Term.h       | 12 +++++++++---
 include/anthem/output/AST.h |  2 ++
 lib/clingo                  |  2 +-
 tests/TestTranslation.cpp   |  8 ++++++++
 5 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/include/anthem/AST.h b/include/anthem/AST.h
index 94e5af3..f5c70fe 100644
--- a/include/anthem/AST.h
+++ b/include/anthem/AST.h
@@ -32,7 +32,8 @@ struct BinaryOperation
 		Minus,
 		Multiplication,
 		Division,
-		Modulo
+		Modulo,
+		Power
 	};
 
 	explicit BinaryOperation(Operator operator_, Term &&left, Term &&right)
diff --git a/include/anthem/Term.h b/include/anthem/Term.h
index 3addeb9..01373f8 100644
--- a/include/anthem/Term.h
+++ b/include/anthem/Term.h
@@ -23,6 +23,12 @@ ast::BinaryOperation::Operator translate(Clingo::AST::BinaryOperator binaryOpera
 {
 	switch (binaryOperator)
 	{
+		case Clingo::AST::BinaryOperator::XOr:
+			throw TranslationException(term.location, "binary operation “xor” currently unsupported");
+		case Clingo::AST::BinaryOperator::Or:
+			throw TranslationException(term.location, "binary operation “or” currently unsupported");
+		case Clingo::AST::BinaryOperator::And:
+			throw TranslationException(term.location, "binary operation “and” currently unsupported");
 		case Clingo::AST::BinaryOperator::Plus:
 			return ast::BinaryOperation::Operator::Plus;
 		case Clingo::AST::BinaryOperator::Minus:
@@ -33,11 +39,11 @@ ast::BinaryOperation::Operator translate(Clingo::AST::BinaryOperator binaryOpera
 			return ast::BinaryOperation::Operator::Division;
 		case Clingo::AST::BinaryOperator::Modulo:
 			return ast::BinaryOperation::Operator::Modulo;
-		default:
-			throw TranslationException(term.location, "“binary operation” terms currently unsupported");
+		case Clingo::AST::BinaryOperator::Power:
+			return ast::BinaryOperation::Operator::Power;
 	}
 
-	return ast::BinaryOperation::Operator::Plus;
+	throw TranslationException(term.location, "unknown binary operation");
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/include/anthem/output/AST.h b/include/anthem/output/AST.h
index a6796af..8f7ea04 100644
--- a/include/anthem/output/AST.h
+++ b/include/anthem/output/AST.h
@@ -85,6 +85,8 @@ inline output::ColorStream &print(output::ColorStream &stream, BinaryOperation::
 			return (stream << output::Operator("/"));
 		case BinaryOperation::Operator::Modulo:
 			return (stream << output::Operator("%"));
+		case BinaryOperation::Operator::Power:
+			return (stream << output::Operator("**"));
 	}
 
 	return stream;
diff --git a/lib/clingo b/lib/clingo
index e2187b6..969ce8f 160000
--- a/lib/clingo
+++ b/lib/clingo
@@ -1 +1 @@
-Subproject commit e2187b697f738f236828f7f780b5481c9a9284e6
+Subproject commit 969ce8f618c4cdf78d5c430ba827217075b88460
diff --git a/tests/TestTranslation.cpp b/tests/TestTranslation.cpp
index e8d38a7..c55f543 100644
--- a/tests/TestTranslation.cpp
+++ b/tests/TestTranslation.cpp
@@ -296,4 +296,12 @@ TEST_CASE("[translation] Rules are translated correctly", "[translation]")
 
 		CHECK(output.str() == "((V1 in U1 and V2 in U2 and exists X1, X2 (X1 in U3 and X2 in U4 and q(X1, X2))) -> p(V1, V2))\n");
 	}
+
+	SECTION("exponentiation operator")
+	{
+		input << "p(N, N ** N) :- N = 1..n.";
+		anthem::translate("input", input, context);
+
+		CHECK(output.str() == "((V1 in U1 and V2 in (U1 ** U1) and exists X1, X2 (X1 in U1 and X2 in 1..n and X1 = X2)) -> p(V1, V2))\n");
+	}
 }