Initial compresison.

src/CMakeLists.txt

@@ -1,4 +1,5 @@
 add_subdirectory(core)
+add_subdirectory(compression)
 add_subdirectory(database)
 add_subdirectory(network)
 add_subdirectory(geometry)

src/compression/CMakeLists.txt

@@ -0,0 +1,15 @@
+
+list(APPEND compression_LIB_INCLUDES 
+    StreamCompressor.cpp
+    HuffmanEncoder.cpp
+    )
+
+add_library(compression SHARED ${compression_LIB_INCLUDES})
+
+target_include_directories(compression PUBLIC
+                          "${CMAKE_CURRENT_SOURCE_DIR}"
+                          )
+                          
+target_link_libraries(compression PUBLIC core)
+set_property(TARGET compression PROPERTY FOLDER src)
+set_target_properties( compression PROPERTIES WINDOWS_EXPORT_ALL_SYMBOLS ON )

src/compression/HuffmanEncoder.cpp

@@ -0,0 +1,77 @@
+#include "HuffmanEncoder.h"
+
+#include "Tree.h"
+
+#include <unordered_map>
+#include <queue>
+#include <tuple>
+#include <iostream>
+
+void HuffmanEncoder::encode(const HuffmanEncoder::DataStream& stream)
+{
+	std::unordered_map<unsigned char, unsigned> counts;
+	for (auto c : stream)
+	{
+		counts[c]++;
+	}
+
+	using CountPair = std::pair<unsigned char, unsigned>;
+	auto cmp = [](CountPair left, CountPair right)
+		{
+			return left.second > right.second;
+		};
+	std::priority_queue<CountPair, std::vector<CountPair>, decltype(cmp)> q(cmp);
+	for (const auto& entry : counts)
+	{
+		q.push({entry.first, entry.second});
+	}
+
+	NodePtr<CountPair> lastNode;
+	while(!q.empty())
+	{
+		const auto charData = q.top();
+		auto characterNode = std::make_unique<Node<CountPair> >(charData);
+		q.pop();
+
+		if (!lastNode)
+		{
+			const auto rightCharData = q.top();
+			auto rightCharacterNode = std::make_unique<Node<CountPair> >(rightCharData);
+			q.pop();
+
+			const auto sum = charData.second + rightCharData.second;
+			CountPair data{0, sum};
+			auto midNode = std::make_unique<Node<CountPair> >(data);
+
+			midNode->addChild(std::move(characterNode));
+			midNode->addChild(std::move(rightCharacterNode));
+			lastNode = std::move(midNode);
+		}
+		else
+		{
+			const auto sum = lastNode->getData().second;
+			CountPair data{0, sum};
+			auto midNode = std::make_unique<Node<CountPair> >(data);
+
+			if (charData.second < lastNode->getData().second)
+			{
+				midNode->addChild(std::move(lastNode));
+				midNode->addChild(std::move(characterNode));
+			}
+			else
+			{
+				midNode->addChild(std::move(characterNode));
+				midNode->addChild(std::move(lastNode));
+			}
+			lastNode = std::move(midNode);
+		}
+	}
+
+	Tree<CountPair> tree;
+	tree.addRootNode(std::move(lastNode));
+
+	//using TableEntry = std::tuple<>
+
+
+	std::cout << "********" << std::endl;
+}

src/compression/HuffmanEncoder.h

@@ -0,0 +1,11 @@
+#pragma once
+
+#include <vector>
+
+class HuffmanEncoder
+{
+using DataStream = std::vector<unsigned char>;
+
+public:
+	void encode(const DataStream& stream);
+};

src/compression/StreamCompressor.h

@@ -0,0 +1,6 @@
+#pragma once
+
+class StreamCompressor
+{
+
+};

src/core/CMakeLists.txt

@@ -15,6 +15,7 @@ list(APPEND core_LIB_INCLUDES
     Dictionary.cpp
     Color.cpp
     CommandLineArgs.cpp
+    data_structures/Tree.cpp
     loggers/FileLogger.cpp
     file_utilities/File.cpp
     file_utilities/FileFormats.cpp
@@ -35,6 +36,7 @@ target_include_directories(core PUBLIC
                           "${CMAKE_CURRENT_SOURCE_DIR}/loggers"
                           "${CMAKE_CURRENT_SOURCE_DIR}/memory"
                           "${CMAKE_CURRENT_SOURCE_DIR}/streams"
+                          "${CMAKE_CURRENT_SOURCE_DIR}/data_structures"
                           )
 set_target_properties( core PROPERTIES WINDOWS_EXPORT_ALL_SYMBOLS ON )
 set_property(TARGET core PROPERTY FOLDER src)

src/core/data_structures/Tree.h

@@ -0,0 +1,66 @@
+#pragma once
+
+#include <memory>
+
+template<typename T>
+class Node
+{
+public:
+	Node(T data)
+		: mData(data)
+	{}
+
+	void addChild(std::unique_ptr<Node> child)
+	{
+		if(!mLeftChild)
+		{
+			mLeftChild = std::move(child);
+		}
+		else
+		{
+			mRightChild = std::move(child);
+		}
+	}
+
+	bool isLeaf() const
+	{
+		return !mLeftChild && !mRightChild;
+	}
+
+	T getData() const
+	{
+		return mData;
+	}
+
+private:
+	T mData;
+	unsigned char mTag{0};
+	std::unique_ptr<Node> mLeftChild;
+	std::unique_ptr<Node> mRightChild;
+};
+
+template<typename T>
+using NodePtr = std::unique_ptr<Node<T> >;
+
+template<typename T>
+class Tree
+{
+public:
+	Tree()
+	{
+
+	}
+
+	void addRootNode(NodePtr<T> root)
+	{
+		mRootNode = std::move(root);
+	}
+
+	Node<T>* getRootNode() const
+	{
+		return mRootNode.get();
+	}
+
+private:
+	NodePtr<T> mRootNode;
+};

test/CMakeLists.txt

@@ -11,6 +11,7 @@ list(APPEND TestFiles
             audio/TestAudioWriter.cpp
             audio/TestMidiReader.cpp
             core/TestBinaryStream.cpp
+            compression/TestStreamCompressor.cpp
             database/TestDatabase.cpp
             fonts/TestFontReader.cpp
             graphics/TestOpenGlRendering.cpp
@@ -30,6 +31,7 @@ list(APPEND TestNames
             TestAudioWriter
             TestMidiReader
             TestBinaryStream
+            TestStreamCompressor
             TestDatabase
             TestFontReader
             TestOpenGlRendering
@@ -52,7 +54,7 @@ link_directories(${DBUS_LIBRARY_DIRS})
 
 foreach(TestFile TestName IN ZIP_LISTS TestFiles TestNames)
     add_executable(${TestName}  ${TestFile})
-    target_link_libraries(${TestName} PUBLIC core fonts network image publishing video database geometry audio graphics web client test_utils ${DBUS_LIBRARIES})
+    target_link_libraries(${TestName} PUBLIC core compression fonts network image publishing video database geometry audio graphics web client test_utils ${DBUS_LIBRARIES})
 endforeach()
 
 

test/compression/TestStreamCompressor.cpp

@@ -0,0 +1,14 @@
+#include <iostream>
+
+#include "HuffmanEncoder.h"
+
+int main()
+{
+	std::string testData = "BCAADDDCCACACAC";
+	std::vector<unsigned char> stream(testData.begin(), testData.end());
+
+	HuffmanEncoder encoder;
+	encoder.encode(stream);
+
+    return 0;
+}