public static HuffmanNode HuffmanNode_Create(HuffmanNode other)
{
return(new HuffmanNode
{
Character = other.Character,
Frequency = other.Frequency,
Left = other.Left != null
? HuffmanNode_Create(other.Left)
: null,
Right = other.Right != null
? HuffmanNode_Create(other.Right)
: null,
});
}
// Etap III
/// <summary>
/// Metoda dokonuje dekompresji tekstu skompresowanego metodą Huffmana
/// </summary>
/// <param name="root">Drzewo Huffmana wykorzystywane do dekompresji</param>
/// <param name="encoding">Skompresowany tekst</param>
/// <returns>Odtworzony tekst</returns>
public string Decompress(HuffmanNode root, BitArray encoding)
{
if (root == null || encoding == null || encoding.Length == 0)
{
throw new ArgumentNullException("invalid inputs");
}
encoderedString = new StringBuilder();
if (root.Left == null && root.Right == null && encoding.Cast <bool>().Any(x => x == true))
{
throw new ArgumentException("incorrect encoding");
}
Decode(root, root, encoding, 0);
return(encoderedString.ToString());
}
private string AssertNoDuplicatedCharacters(HuffmanNode root)
{
var visitedCharacters = new SortedSet <char>();
return(NodeVisitor(root, node =>
{
if (node.Character > 0)
{
if (visitedCharacters.Contains(node.Character))
{
return $"{root.Character} was encountered more than once in huffman tree";
}
visitedCharacters.Add(node.Character);
}
return null;
}));
}
private string AssertNoCircularReferences(HuffmanNode root)
{
var visitedNodes = new List <HuffmanNode>();
return(NodeVisitor(root, node =>
{
string errorMessage = null;
visitedNodes.ForEach(visitedNode =>
{
if (ReferenceEquals(visitedNode, node))
{
errorMessage = "Huffman tree contains circular references";
}
});
visitedNodes.Add(node);
return errorMessage;
}));
}
public static bool HuffmanNode_Equals(HuffmanNode lhs, HuffmanNode rhs)
{
if (lhs == null && rhs == null)
{
return(true);
}
if (lhs != null && rhs != null)
{
if (lhs.Character != rhs.Character)
{
return(false);
}
if (lhs.Frequency != rhs.Frequency)
{
return(false);
}
return(HuffmanNode_Equals(lhs.Left, rhs.Left) && HuffmanNode_Equals(lhs.Right, rhs.Right));
}
return(false);
}
private string AssertOnlyBaseTextCharacters(HuffmanNode root)
{
bool[] characters = new bool[char.MaxValue];
foreach (char character in baseText)
{
characters[character] = true;
}
return(NodeVisitor(root, node =>
{
if (node.Character > 0)
{
if (!characters[node.Character])
{
return $"Huffman tree should contains only characters that were in base text";
}
}
return null;
}));
}
private string AssertTreeStructure(HuffmanNode root)
{
return(NodeVisitor(root, node =>
{
if (node.Frequency <= 0)
{
return "Node should have positive frequency";
}
if (node.Character == 0)
{
if (node.Left == null)
{
return "Non-terminating node (character==0) should have left descendant";
}
if (node.Right == null)
{
return "Non-terminating node (character==0) should have right descendant";
}
if (node.Frequency != node.Right.Frequency + node.Left.Frequency)
{
return "Non-terminating node (character==0) should have frequency equal to sum of descendant frequencies";
}
}
else
{
if (node.Left != null)
{
return $"Leaf node (character='{node.Character}') should not have left descendant";
}
if (node.Right != null)
{
return $"Leaf node (character='{node.Character}') should not have right descendant";
}
}
return null;
}));
}
/// <summary>
/// Metoda tworzy drzewo Huffmana dla zadanego tekstu
/// </summary>
/// <param name="baseText">Zadany tekst</param>
/// <returns>Drzewo Huffmana</returns>
public HuffmanNode CreateHuffmanTree(string baseText)
{
if (baseText == null || baseText.Length == 0)
{
throw new ArgumentNullException("invalid string");
}
var counter = Counter(baseText);
HuffmanPriorityQueue pq = new HuffmanPriorityQueue();
//var orderedCount = counter.OrderBy(x => x.Value);
foreach (var c in counter)
{
var hn = new HuffmanNode();
hn.Character = c.Key;
hn.Frequency = c.Value;
hn.Left = null;
hn.Right = null;
pq.Put(hn);
}
while (pq.Count > 1)
{
var t1 = pq.Get();
var t2 = pq.Get();
var hn = new HuffmanNode();
hn.Frequency = t1.Frequency + t2.Frequency;
hn.Left = t1;
hn.Right = t2;
pq.Put(hn);
}
return(pq.Get());
}
private HuffmanNode[] DefineSampleTrees() // 5 drzew
{
HuffmanNode[] _trees = new HuffmanNode[] {
new HuffmanNode
{
Frequency = 42,
Character = 'a'
}, // a -> 0;
new HuffmanNode
{
Frequency = 5,
Left = new HuffmanNode
{
Character = 'b',
Frequency = 3,
},
Right = new HuffmanNode
{
Character = 'c',
Frequency = 2,
}
}, // b -> 0; c -> 1
new HuffmanNode
{
Frequency = 11,
Left = new HuffmanNode
{
Character = 'a',
Frequency = 5,
},
Right = new HuffmanNode
{
Frequency = 6,
Left = new HuffmanNode
{
Character = 'c',
Frequency = 2,
},
Right = new HuffmanNode
{
Character = 'b',
Frequency = 4,
}
}
}, // a -> 0; b -> 11; c -> 10;
new HuffmanNode
{
Frequency = 12,
Left = new HuffmanNode
{
Character = 'a',
Frequency = 5,
},
Right = new HuffmanNode
{
Character = 'b',
Frequency = 7,
},
}, // a -> 0; b -> 1
new HuffmanNode
{
Frequency = 12,
Left = new HuffmanNode
{
Character = 'b',
Frequency = 7,
},
Right = new HuffmanNode
{
Character = 'a',
Frequency = 5,
},
} // a -> 1; b -> 0
};
return(_trees);
}
public HuffmanDecompressTestCase(double timeLimit, Exception expectedException, string description, HuffmanNode tree, BitArray encoding, string expectedResult)
: base(timeLimit, expectedException, description)
{
this.tree = tree;
this.encoding = encoding;
this.expectedResult = expectedResult;
treeCopy = HuffmanNode_DeepClone(tree);
}
public static HuffmanNode HuffmanNode_DeepClone(HuffmanNode node)
{
return(node == null
? null
: HuffmanNode_Create(node));
}
public bool Put(HuffmanNode node) => queue.Put(node, node.Frequency); // Dodaje węzeł Huffmana do kolejki