1 files changed, 167 insertions, 0 deletions

diff --git a/src/BlockState.cpp b/src/BlockState.cpp
new file mode 100644
index 000000000..4e2607bd3
--- /dev/null
+++ b/src/BlockState.cpp
@@ -0,0 +1,167 @@
+#include "Globals.h"
+#include "BlockState.h"
+
+
+
+
+
+BlockState::BlockState():
+	mChecksum(initializeChecksum())
+{
+	// Nothing needed yet
+}
+
+
+
+
+
+BlockState::BlockState(const AString & aKey, const AString & aValue):
+	mState({{aKey, aValue}}),
+	mChecksum(initializeChecksum())
+{
+}
+
+
+
+
+
+BlockState::BlockState(std::initializer_list<std::pair<const AString, AString>> aKeysAndValues):
+	mState(aKeysAndValues),
+	mChecksum(initializeChecksum())
+{
+}
+
+
+
+
+
+BlockState::BlockState(const std::map<AString, AString> & aKeysAndValues):
+	mState(aKeysAndValues),
+	mChecksum(initializeChecksum())
+{
+}
+
+
+
+
+
+BlockState::BlockState(std::map<AString, AString> && aKeysAndValues):
+	mState(std::move(aKeysAndValues)),
+	mChecksum(initializeChecksum())
+{
+}
+
+
+
+
+
+BlockState::BlockState(const BlockState & aCopyFrom, std::initializer_list<std::pair<const AString, AString>> aAdditionalKeysAndValues):
+	mState(aCopyFrom.mState)
+{
+	for (const auto & kav: aAdditionalKeysAndValues)
+	{
+		mState[kav.first] = kav.second;
+	}
+	mChecksum = initializeChecksum();
+}
+
+
+
+
+
+BlockState::BlockState(const BlockState & aCopyFrom, const std::map<AString, AString> & aAdditionalKeysAndValues):
+	mState(aCopyFrom.mState)
+{
+	for (const auto & kav: aAdditionalKeysAndValues)
+	{
+		mState[kav.first] = kav.second;
+	}
+	mChecksum = initializeChecksum();
+}
+
+
+
+
+
+bool BlockState::operator ==(const BlockState & aOther) const
+{
+	// Fast-fail if the checksums differ or differrent counts:
+	if ((mChecksum != aOther.mChecksum) || (mState.size() != aOther.mState.size()))
+	{
+		return false;
+	}
+
+	// Slow-check everything if the checksums match:
+	return std::equal(mState.begin(), mState.end(), aOther.mState.begin());
+}
+
+
+
+
+
+const AString & BlockState::value(const AString & aKey) const
+{
+	auto itr = mState.find(aKey);
+	if (itr == mState.end())
+	{
+		static AString empty;
+		return empty;
+	}
+	return itr->second;
+}
+
+
+
+
+
+UInt32 BlockState::initializeChecksum()
+{
+	removeEmptyKeys();
+
+	// Calculate the checksum as a XOR of all mState keys' and values' checksums
+	// This way we don't depend on the std::map's ordering
+	UInt32 res = 0;
+	for (const auto & kv: mState)
+	{
+		auto partial = partialChecksum(kv.first) ^ partialChecksum(kv.second);
+		res = res ^ partial;
+	}
+	return res;
+}
+
+
+
+
+
+void BlockState::removeEmptyKeys()
+{
+	for (auto itr = mState.begin(); itr != mState.end();)
+	{
+		if (itr->second.empty())
+		{
+			itr = mState.erase(itr);
+		}
+		else
+		{
+			++itr;
+		}
+	}
+}
+
+
+
+
+
+UInt32 BlockState::partialChecksum(const AString & aString)
+{
+	UInt32 shift = 0;
+	UInt32 res = 0;
+	for (auto ch: aString)
+	{
+		UInt32 v = static_cast<UInt8>(ch);
+		v = v << shift;
+		shift = (shift + 1) % 24;
+		res = res ^ v;
+	}
+	return res;
+}