add exponent operator

https://www.pivotaltracker.com/n/projects/1189488/stories/83746404

4 files changed, 24 insertions, 4 deletions

diff --git a/ExpressionCompiler.cpp b/ExpressionCompiler.cpp
index 1d3f23e6..beda0132 100644
--- a/ExpressionCompiler.cpp
+++ b/ExpressionCompiler.cpp
@@ -650,6 +650,9 @@ void ExpressionCompiler::appendArithmeticOperatorCode(Token::Value _operator, Ty
 	case Token::Mod:
 		m_context << (c_isSigned ? eth::Instruction::SMOD : eth::Instruction::MOD);
 		break;
+	case Token::Exp:
+		m_context << eth::Instruction::EXP;
+		break;
 	default:
 		BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Unknown arithmetic operator."));
 	}
diff --git a/Scanner.cpp b/Scanner.cpp
index fc4bdb6b..fbe3ea97 100644
--- a/Scanner.cpp
+++ b/Scanner.cpp
@@ -465,8 +465,14 @@ void Scanner::scanToken()
 				token = Token::Sub;
 			break;
 		case '*':
-			// * *=
-			token = selectToken('=', Token::AssignMul, Token::Mul);
+			// * ** *=
+			advance();
+			if (m_char == '*')
+				token = selectToken(Token::Exp);
+			else if (m_char == '=')
+				token = selectToken(Token::AssignMul);
+			else
+				token = Token::Mul;
 			break;
 		case '%':
 			// % %=
diff --git a/Token.h b/Token.h
index b913f0ce..ac8c618f 100644
--- a/Token.h
+++ b/Token.h
@@ -118,6 +118,7 @@ namespace solidity
 	T(Mul, "*", 13)                                                    \
 	T(Div, "/", 13)                                                    \
 	T(Mod, "%", 13)                                                    \
+	T(Exp, "**", 14)                                                   \
 	\
 	/* Compare operators sorted by precedence. */                      \
 	/* IsCompareOp() relies on this block of enum values */            \
@@ -361,10 +362,10 @@ public:
 	// Predicates
 	static bool isElementaryTypeName(Value tok) { return Int <= tok && tok < TypesEnd; }
 	static bool isAssignmentOp(Value tok) { return Assign <= tok && tok <= AssignMod; }
-	static bool isBinaryOp(Value op) { return Comma <= op && op <= Mod; }
+	static bool isBinaryOp(Value op) { return Comma <= op && op <= Exp; }
 	static bool isCommutativeOp(Value op) { return op == BitOr || op == BitXor || op == BitAnd ||
 				op == Add || op == Mul || op == Equal || op == NotEqual; }
-	static bool isArithmeticOp(Value op) { return Add <= op && op <= Mod; }
+	static bool isArithmeticOp(Value op) { return Add <= op && op <= Exp; }
 	static bool isCompareOp(Value op) { return Equal <= op && op <= In; }
 
 	static Value AssignmentToBinaryOp(Value op)
diff --git a/Types.cpp b/Types.cpp
index 6fd9e8b4..dcc0738d 100644
--- a/Types.cpp
+++ b/Types.cpp
@@ -320,6 +320,16 @@ TypePointer IntegerConstantType::binaryOperatorResult(Token::Value _operator, Ty
 				return TypePointer();
 			value = m_value % other.m_value;
 			break;
+		case Token::Exp:
+			if (other.m_value < 0)
+				BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("exponent can't be negative"));
+			else
+			{
+				value = boost::multiprecision::powm(m_value, other.m_value, bigint(2) << 256);
+				if (value >= (bigint(1) << 256))
+					BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("exp result overflowed"));
+			}
+			break;
 		default:
 			return TypePointer();
 		}