Initial fixed huffman coding for png.

src/compression/huffman/HuffmanEncoder.cpp

@@ -0,0 +1,100 @@
+#include "HuffmanEncoder.h"
+
+#include "RawTree.h"
+
+#include <unordered_map>
+#include <queue>
+#include <tuple>
+#include <iostream>
+
+void HuffmanEncoder::dumpNode(RawNode<CountPair>* node, unsigned depth) const
+{
+    if (!node)
+    {
+        return;
+    }
+
+    auto data = node->getData();
+
+    std::string prefix(depth, '_');
+
+    if (node->isLeaf())
+    {
+        std::cout << prefix << "Leaf with value: " << data.first << " and sum " << data.second << std::endl;
+    }
+    else
+    {
+        std::cout << prefix << "Intermediate with sum " << data.second << std::endl;
+        std::cout << prefix << "Doing Left.." << std::endl;
+        dumpNode(node->getLeftChild(), depth+1);
+
+        std::cout << prefix << "Doing Right.." << std::endl;
+        dumpNode(node->getRightChild(), depth+1);
+
+        std::cout << prefix << "*****" << std::endl;
+    }
+}
+
+void HuffmanEncoder::dumpTree(const RawTree<CountPair>& tree) const
+{
+    dumpNode(tree.getRootNode(), 0);
+}
+
+void HuffmanEncoder::encode(const HuffmanEncoder::DataStream& stream)
+{
+    std::unordered_map<unsigned char, unsigned> counts;
+    for (auto c : stream)
+    {
+        counts[c]++;
+    }
+    encode(counts);
+}
+
+void HuffmanEncoder::encode(const std::unordered_map<unsigned char, unsigned>& counts)
+{
+    std::cout << "Counts" << std::endl;
+    for (const auto& data: counts)
+    {
+        std::cout << data.first << " | " << data.second << std::endl;
+    }
+    std::cout << "*******" << std::endl;
+
+    auto cmp = [](RawNode<CountPair>* left, RawNode<CountPair>* right)
+        {
+            return left->getData().second > right->getData().second;
+        };
+
+    std::priority_queue<RawNode<CountPair>*, std::vector<RawNode<CountPair>* >, decltype(cmp)> q(cmp);
+    for (const auto& entry : counts)
+    {
+        q.push(new RawNode<CountPair>(entry));
+    }
+
+    while(q.size() > 1)
+    {
+        auto node0 = q.top();
+        q.pop();
+
+        auto node1 = q.top();
+        q.pop();
+
+        const auto sum = node0->getData().second + node1->getData().second;
+        auto new_node = new RawNode<CountPair>(CountPair{0, sum});
+
+        new_node->addChild(node0);
+        new_node->addChild(node1);
+        q.push(new_node);
+    }
+
+    auto root = q.top();
+    q.pop();
+
+    RawTree<CountPair> tree;
+    tree.addRootNode(root);
+
+    //using TableEntry = std::tuple<>
+
+    dumpTree(tree);
+
+    std::cout << "********" << std::endl;
+}