Merge pull request #857 from LianaHus/StringToHash

conversion for string to/from hash

3 files changed, 69 insertions, 25 deletions

diff --git a/ExpressionCompiler.cpp b/ExpressionCompiler.cpp
index 60c5c4de..bd8c8653 100644
--- a/ExpressionCompiler.cpp
+++ b/ExpressionCompiler.cpp
@@ -628,38 +628,65 @@ void ExpressionCompiler::appendTypeConversion(Type const& _typeOnStack, Type con
 		return;
 	Type::Category stackTypeCategory = _typeOnStack.getCategory();
 	Type::Category targetTypeCategory = _targetType.getCategory();
-	if (stackTypeCategory == Type::Category::INTEGER || stackTypeCategory == Type::Category::CONTRACT ||
-			 stackTypeCategory == Type::Category::INTEGER_CONSTANT)
+
+	if (stackTypeCategory == Type::Category::STRING)
 	{
-		solAssert(targetTypeCategory == Type::Category::INTEGER || targetTypeCategory == Type::Category::CONTRACT, "");
-		IntegerType addressType(0, IntegerType::Modifier::ADDRESS);
-		IntegerType const& targetType = targetTypeCategory == Type::Category::INTEGER
-			? dynamic_cast<IntegerType const&>(_targetType) : addressType;
-		if (stackTypeCategory == Type::Category::INTEGER_CONSTANT)
+		if (targetTypeCategory == Type::Category::INTEGER)
 		{
-			IntegerConstantType const& constType = dynamic_cast<IntegerConstantType const&>(_typeOnStack);
-			// We know that the stack is clean, we only have to clean for a narrowing conversion
-			// where cleanup is forced.
-			if (targetType.getNumBits() < constType.getIntegerType()->getNumBits() && _cleanupNeeded)
-				appendHighBitsCleanup(targetType);
+			// conversion from string to hash. no need to clean the high bit
+			// only to shift right because of opposite alignment
+			IntegerType const& targetIntegerType = dynamic_cast<IntegerType const&>(_targetType);
+			StaticStringType const& typeOnStack = dynamic_cast<StaticStringType const&>(_typeOnStack);
+			solAssert(targetIntegerType.isHash(), "Only conversion between String and Hash is allowed.");
+			solAssert(targetIntegerType.getNumBits() == typeOnStack.getNumBytes() * 8, "The size should be the same.");
+			m_context << (u256(1) << (256 - typeOnStack.getNumBytes() * 8)) << eth::Instruction::SWAP1 << eth::Instruction::DIV;
 		}
 		else
 		{
-			IntegerType const& typeOnStack = stackTypeCategory == Type::Category::INTEGER
-				? dynamic_cast<IntegerType const&>(_typeOnStack) : addressType;
-			// Widening: clean up according to source type width
-			// Non-widening and force: clean up according to target type bits
-			if (targetType.getNumBits() > typeOnStack.getNumBits())
-				appendHighBitsCleanup(typeOnStack);
-			else if (_cleanupNeeded)
-				appendHighBitsCleanup(targetType);
+			solAssert(targetTypeCategory == Type::Category::STRING, "Invalid type conversion requested.");
+			// nothing to do, strings are high-order-bit-aligned
+			//@todo clear lower-order bytes if we allow explicit conversion to shorter strings
 		}
 	}
-	else if (stackTypeCategory == Type::Category::STRING)
+	else if (stackTypeCategory == Type::Category::INTEGER || stackTypeCategory == Type::Category::CONTRACT ||
+			 stackTypeCategory == Type::Category::INTEGER_CONSTANT)
 	{
-		solAssert(targetTypeCategory == Type::Category::STRING, "");
-		// nothing to do, strings are high-order-bit-aligned
-		//@todo clear lower-order bytes if we allow explicit conversion to shorter strings
+		if (targetTypeCategory == Type::Category::STRING && stackTypeCategory == Type::Category::INTEGER)
+		{
+			// conversion from hash to string. no need to clean the high bit
+			// only to shift left because of opposite alignment
+			StaticStringType const& targetStringType = dynamic_cast<StaticStringType const&>(_targetType);
+			IntegerType const& typeOnStack = dynamic_cast<IntegerType const&>(_typeOnStack);
+			solAssert(typeOnStack.isHash(), "Only conversion between String and Hash is allowed.");
+			solAssert(typeOnStack.getNumBits() == targetStringType.getNumBytes() * 8, "The size should be the same.");
+			m_context << (u256(1) << (256 - typeOnStack.getNumBits())) << eth::Instruction::MUL;
+		}
+		else
+		{
+			solAssert(targetTypeCategory == Type::Category::INTEGER || targetTypeCategory == Type::Category::CONTRACT, "");
+			IntegerType addressType(0, IntegerType::Modifier::ADDRESS);
+			IntegerType const& targetType = targetTypeCategory == Type::Category::INTEGER
+											? dynamic_cast<IntegerType const&>(_targetType) : addressType;
+			if (stackTypeCategory == Type::Category::INTEGER_CONSTANT)
+			{
+				IntegerConstantType const& constType = dynamic_cast<IntegerConstantType const&>(_typeOnStack);
+				// We know that the stack is clean, we only have to clean for a narrowing conversion
+				// where cleanup is forced.
+				if (targetType.getNumBits() < constType.getIntegerType()->getNumBits() && _cleanupNeeded)
+					appendHighBitsCleanup(targetType);
+			}
+			else
+			{
+				IntegerType const& typeOnStack = stackTypeCategory == Type::Category::INTEGER
+												? dynamic_cast<IntegerType const&>(_typeOnStack) : addressType;
+				// Widening: clean up according to source type width
+				// Non-widening and force: clean up according to target type bits
+				if (targetType.getNumBits() > typeOnStack.getNumBits())
+					appendHighBitsCleanup(typeOnStack);
+				else if (_cleanupNeeded)
+					appendHighBitsCleanup(targetType);
+			}
+		}
 	}
 	else if (_typeOnStack != _targetType)
 		// All other types should not be convertible to non-equal types.
diff --git a/Types.cpp b/Types.cpp
index c75cecfa..dad3a145 100644
--- a/Types.cpp
+++ b/Types.cpp
@@ -140,6 +140,11 @@ bool IntegerType::isImplicitlyConvertibleTo(Type const& _convertTo) const
 
 bool IntegerType::isExplicitlyConvertibleTo(Type const& _convertTo) const
 {
+	if (_convertTo.getCategory() == Category::STRING)
+	{
+		StaticStringType const& convertTo = dynamic_cast<StaticStringType const&>(_convertTo);
+		return isHash() && (m_bits == convertTo.getNumBytes() * 8);
+	}
 	return _convertTo.getCategory() == getCategory() || _convertTo.getCategory() == Category::CONTRACT;
 }
 
@@ -367,6 +372,17 @@ bool StaticStringType::isImplicitlyConvertibleTo(Type const& _convertTo) const
 	return convertTo.m_bytes >= m_bytes;
 }
 
+bool StaticStringType::isExplicitlyConvertibleTo(Type const& _convertTo) const
+{
+	if (_convertTo.getCategory() == Category::INTEGER)
+	{
+		IntegerType const& convertTo = dynamic_cast<IntegerType const&>(_convertTo);
+		if (convertTo.isHash() && (m_bytes * 8 == convertTo.getNumBits()))
+			return true;
+	}
+	return isImplicitlyConvertibleTo(_convertTo);
+}
+
 bool StaticStringType::operator==(Type const& _other) const
 {
 	if (_other.getCategory() != getCategory())
diff --git a/Types.h b/Types.h
index 935c39eb..83436efa 100644
--- a/Types.h
+++ b/Types.h
@@ -233,9 +233,10 @@ public:
 	/// if no type fits.
 	static std::shared_ptr<StaticStringType> smallestTypeForLiteral(std::string const& _literal);
 
-	StaticStringType(int _bytes);
+	explicit StaticStringType(int _bytes);
 
 	virtual bool isImplicitlyConvertibleTo(Type const& _convertTo) const override;
+	virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const override;
 	virtual bool operator==(Type const& _other) const override;
 
 	virtual unsigned getCalldataEncodedSize() const override { return m_bytes; }