//Method used for compressing files
static void Compress(string input, string output)
{
//start of method
//Initilize variables
int totalChars = 0; //Counts number of characters in file, used for decompression purposes
BinaryTree <CharacterFrequency> charTree = new BinaryTree <CharacterFrequency>();
StreamReader read = new StreamReader(input);
//Create a dictionary of CharacterFrequency objects with the int key being the ascii code of each character
IDictionary <int, CharacterFrequency> charDictionary = new Dictionary <int, CharacterFrequency>();
//Read entire file character by character...
while (!read.EndOfStream)
{
int i = read.Read();
//checks if Dictionary contains the char i...
if (!charDictionary.ContainsKey(i))
{
//if not add new record to dictionary
charDictionary.Add(i, new CharacterFrequency((char)i, 1));
}
else
{
//if so increment the frequency of this record
charDictionary[i].increment();
}
totalChars++;
}
read.Close();
//Create ordered linked list of TreeNode<CharacterFrequency> objects
OrderedLinkedList <TreeNode <CharacterFrequency> > orderedNodeList = new OrderedLinkedList <TreeNode <CharacterFrequency> >();
//Go throughs each KeyValuePair in the CharacterFrequency dicitionary..
foreach (KeyValuePair <int, CharacterFrequency> c in charDictionary)
{
//Make a new TreeNode of the CharacterFrequency value from c...
TreeNode <CharacterFrequency> node = new TreeNode <CharacterFrequency>(c.Value);
//add into the ordered linked list of TreeNode<CharacterFrequency>
orderedNodeList.Add(node);
}
//Run a method in the binary tree to convert the ordered node list into a single node with branching children container all other nodes
//and return and set said node as the root node of the tree
charTree.Insert(charTree.TransferListToTree(orderedNodeList).GetFirst(), Relative.Root);
//Run a method from the tree to return a list of BinaryPath objects
LinkedList <BinaryPath <CharacterFrequency> > binaryTable = charTree.BinaryTable(charTree.Root);
//Removes all nodes from the binarytable that have a null character as they cannot show up in a file
var binary = binaryTable.First;
while (binary != null)
{
var nextNode = binary.Next;
if (binary.Value.Element.Character == '\0')
{
binaryTable.Remove(binary);
}
binary = nextNode;
}
//Byte writing section
int bitPosition = 7; //creates an int that determines what bit in the byte to set
byte y = 0; //creates the byte to set and write with
BinaryWriter binaryWriter = null;
bool error = true;
while (error)
{
try
{
binaryWriter = new BinaryWriter(File.Create(CheckFile(output)));
error = false;
}
catch (UnauthorizedAccessException ex)
{
MessageBox.Show("You do not have the permissions needed to write to this folder");
}
}
StreamReader streamReader = new StreamReader(input);
//string of the entire table, to used to append to the beginning of the output file. Will be read by out in decompression process
string tableText = String.Empty;
//Take the total characters from the input file and append to the beginning of the output file
tableText += totalChars + "~~~";
//Take table and write to output file
foreach (BinaryPath <CharacterFrequency> bp in binaryTable)
{
tableText += bp.Element.Character + bp.Path + ";";
}
binaryWriter.Write(tableText);
//Compression process
while (!streamReader.EndOfStream)
{
//Read each character from file..
int i = streamReader.Read();
//Find path of character from binary table...
string path = binaryTable.FirstOrDefault(obj => obj.Element.Character == (char)i).Path;
//Iterate through each character in path...
foreach (char c in path)
{
//If bitposition = 0 we have set all other bits
if (bitPosition == 0)
{
//if character is '1' set bit at bitposition in byte to 1 using bitwise OR(|)
if (c == '1')
{
y = (byte)(y | (byte)Math.Pow(2, bitPosition));
}
//Writes byte to output file
binaryWriter.Write(y);
//Resets byte and bitposition
y = 0;
bitPosition = 7;
}
//If bitposition != 0
else
{
//if character is '1' set bit at bitposition in byte to 1 using bitwise OR(|)
if (c == '1')
{
y = (byte)(y | (byte)Math.Pow(2, bitPosition));
}
//progresses bitposition down 1 to next bit in byte
bitPosition--;
}
}
}
//Close stream reader
read.Close();
//write final byte to output file and close BinaryWriter
binaryWriter.Write(y);
binaryWriter.Close();
//Output to command prompt to let user know file is finished being compressied, end program
Console.WriteLine($"File has been compressed to the file {output}");
}
static void Decompress(string input, string output)
{
//get tuple from method
var tuple = GetTableFromFile(input);
//get binary reader from tuple to maintain stream position
BinaryReader read = tuple.Item3;
StreamWriter write = null;
bool error = true;
while (error)
{
try
{
write = new StreamWriter(CheckFile(output));
error = false;
}
catch (UnauthorizedAccessException ex)
{
MessageBox.Show("You do not have the permissions needed to write to this folder");
}
}
//get total number of characters to write to output file from method
int totalChar = tuple.Item2;
//get binary path array from tuple
BinaryPath <char>[] binaryCharTable = tuple.Item1;
BinaryTree <TreeNode <char> > tree = new BinaryTree <TreeNode <char> >();
//create root note in binary tree
tree.Insert(new TreeNode <char>(), Relative.Root);
//iterate through the binary paths for each character...
foreach (BinaryPath <char> bp in binaryCharTable)
{
tree.moveTo(Relative.Root);
int i = 1;
//navigate through tree using characters from path of binarypath object bp
foreach (char c in bp.Path)
{
//if character is a 1...
if (c == '1')
{
//and if the next left node does not exist but we have reached the end of the path...
if (tree.Current.Left == null && i == bp.Path.Length)
{
//insert a new node to the left with the value being the character of the bp object
tree.Insert(new TreeNode <char>(bp.Element), Relative.LeftChild);
}
//or if the next left node does not exist but we are not at the end of the path...
else if (tree.Current.Left == null)
{
//insert a new null node to the left...
tree.Insert(new TreeNode <char>(), Relative.LeftChild);
//then move to this new node and continue the loop
tree.moveTo(Relative.LeftChild);
i++;
}
//or if the next left node does exist...
else
{
//then move to the next left node...
tree.moveTo(Relative.LeftChild);
//and continue the loop
i++;
}
}
//else if the character in the path is a 0...
else
{
//and if the next right node does not exist but we have reached the end of the path...
if (tree.Current.Right == null && i == bp.Path.Length)
{
//insert a new node to the right with the value being the character of the bp object
tree.Insert(new TreeNode <char>(bp.Element), Relative.RightChild);
}
//or if the next right node does not exist but we are not at the end of the path...
else if (tree.Current.Right == null)
{
//insert a new null node to the right...
tree.Insert(new TreeNode <char>(), Relative.RightChild);
//then move to this new node and continue the loop
tree.moveTo(Relative.RightChild);
i++;
}
//or if the right node does exist...
else
{
//then move to the next right node...
tree.moveTo(Relative.RightChild);
//and continue the loop
i++;
}
}
}
}
//once the tree is complete move back to the root
tree.moveTo(Relative.Root);
//Decompression process
//create byte for reading purposes
byte b = 0;
//number of characters read from the file, to be compaired to the number of characters needing to be written for the output file
int charWritten = 0;
//Continue to read the next byte in the file until we have reached it's end
while (read.BaseStream.Position != read.BaseStream.Length)
{
//get the next byte
b = read.ReadByte();
//loop to iterate through each bit in the byte starting at the 8th position and going backwards
for (int i = 128; i > 0; i = i / 2)
{
//a check to see if we have written all the characters we need to the output file, if not then continue the navigation
if (charWritten != totalChar)
{
//using bitwise AND to check if the bit at the current position is a 0...
if ((b & i) == 0)
{
//if it is a 0, move to the right child of the current node in the tree
tree.moveTo(Relative.RightChild);
//check if the node we moved to is a leaf
if (tree.Current.isLeaf)
{
//if it is a leaf, write the character from that leaf to the output file, and move back to the tree's root node
write.Write(tree.Current.Element.Element);
tree.moveTo(Relative.Root);
charWritten++;
}
}
//or a 1
else
{
//if it is a 1, move to the left child of the current node in the tree
tree.moveTo(Relative.LeftChild);
//check if the node we moved to is a leaf
if (tree.Current.isLeaf)
{
//if it is a leaf, write the character from that leaf to the output file, and move back to the tree's root node
write.Write(tree.Current.Element.Element);
tree.moveTo(Relative.Root);
charWritten++;
}
}
}
}
}
//close the stream writer and output to screen the file has been decompressed and to what file, end program
write.Close();
Console.WriteLine($"File has been decompressed to the file {output}");
}
