Thorns

Basic data structures in C# convenient for many applications.

The package only contains trees, at the moment.

Behind the Name

The name Thorns is a reference to how the package is for collections in C#. The "sharp" from C# was taken to develop a notion of "collection of sharp objects", which thorns are a simple example of.

This assembly contains two tree classes: Tree and OrderedTree. Their methods and implementations are more or less the seem, with the only difference being the Tree uses a HashSet to store its children, whereas an OrderedTree uses a List. In short, the elements of the Tree are not ordered, whereas the elements of OrderedTree are.

Examples

Create and Modify

Here's a general example of how to create and modify trees.

Tree<int> t = new Tree<int>(4);				// 1
Tree<int> ch = t.AddChild(3);				// 2
t.AddChildren(4,7,9);						// 3
t.AddChildren(new List<int> {-34,0,16});	// 4
ch.AddChild(12);
t.RemoveChild(7);							// 5
t.RemoveChild(63);							// Does nothing

This image shows how the tree node t is modified by the code above.

The lines of code:

Tree<int> ch = t.AddChild(3);				// 2
ch.AddChild(12);

show how to insert grandchild nodes into the tree.

To ensure safe and secure implementations of the tree, we don't have a method which adds a tree node as a child, as the tree instance may already have a parent.

Iterations and Containment

The two typical iterations over trees are provide in the TreeIter static class.

HasChild and Has

The HasChild method simply checks if the tree instance has the given child.

The Has method iterates over all descendants, breadth-first, by default. If you want, you can define and pass a custom iteration for it to implement. Use this method with default arguments to see if the tree has a given descendant:

Tree<string> tree = new Tree("Abc");

Tree<string> ch1 = tree.AddChild("Cha");
Tree<string> ch2 = ch1.AddChild("Rac");

bool hasChild = tree.HasChild(ch1); // true
bool hasChild2 = tree.HasChild(new Tree<string>("Cha")); // false
bool hasDescendant = tree.Has(ch2); // true

Note that creating a new tree is not

Properties and Methods

All of the methods below also apply to OrderedTree.

Return Type	Method	Description
Constructor	Tree(T val)	Creates a root tree node.
HashSet<Tree>	Children()	The set of all children of the tree.
Tree	AddChild(T val)	Adds a child to the tree, then returns the instance of the tree node create.
IEnumerable<Tree>	AddChildren(params T[] values)	Adds children with the provided values to the tree, then returns an iterator to the instances created.
IEnumerable<Tree>	AddChildren(IEnumerable values)	Adds children with the provided values to the tree, then returns an iterator to the instances created.
bool	RemoveChild(Tree child)	Removes the child from this instance, if it exists. If it does, return true. If not, return false.
bool	HasChild(Tree child)	True if this instance has the child parameter as its child, false if not.
bool	Has(Tree tree, Func<Tree, IEnumerable<Tree> iter)	Iterates over the tree by iter checks if the tree contains it.
bool	HasValue(T value)	Checks if the tree contains the given value
IEnumerable<Tree>	WhereByValue(Func<T, bool> cond, Func<Tree, IEnumerable<Tree> iter)	Returns all elements in the iteration that satisfy the given condition by value.
IEnumerable<Tree>	WhereByValue(T value, Func<Tree, IEnumerable<Tree> iter)	Returns all elements in the iteration by value.
Tree	FirstByValue(T value, Func<Tree, IEnumerable<Tree> iter)	Returns the first tree instance with the given value.
Tree	Root	The root of the tree.
HashSet<Tree>	Siblings	The siblings of this tree instance.