/// <summary>
/// Add a new key/value pair.
/// </summary>
/// <param name="key">The key</param>
/// <param name="val">The value</param>
/// <returns>A new map with key+value added.</returns>
/// <remarks>Overwrites an exising value for the <paramref name="key"/>, if present.</remarks>
public override IPersistentMap assoc(object key, object val)
{
Box addedLeaf = new Box(null);
INode newroot = _root.assoc(0, Util.Hash(key), key, val, addedLeaf);
return(newroot == _root
? this
: new PersistentHashMap(meta(), addedLeaf.Val == null ? _count : _count + 1, newroot));
}
/// <summary>
/// Remove a key entry.
/// </summary>
/// <param name="key">The key to remove</param>
/// <returns>A new map with the key removed (or the same map if the key is not contained).</returns>
public override IPersistentMap without(object key)
{
INode newroot = _root.without(Util.Hash(key), key);
return(newroot == _root
? this
: (newroot == null
? (IPersistentMap)EMPTY.withMeta(meta())
: new PersistentHashMap(meta(), _count - 1, newroot)));
}
/// <summary>
/// Get the hash code for the current object.
/// </summary>
/// <returns>The hash code.</returns>
/// <remarks>Result is cached.</remarks>
public override int GetHashCode()
{
if (_hash == -1)
{
int hash = 0;
for (ISeq s = seq(); s != null; s = s.next())
{
hash = Util.HashCombine(hash, Util.Hash(s.first()));
}
_hash = hash;
}
return(_hash);
}
/// <summary>
/// Compute a hash code for the current object.
/// </summary>
/// <returns>A hash code for the current object.</returns>
public override int GetHashCode()
{
if (_hash == -1)
{
int hash = 0;
for (int i = 0; i < count(); i++)
{
hash = Util.HashCombine(hash, Util.Hash(nth(i)));
}
this._hash = hash;
}
return(_hash);
}
/// <summary>
/// Computes a hash code for the current object.
/// </summary>
/// <returns>A hash code for the current object.</returns>
/// <remarks>The hash code is value-based (based on the items in the set).
/// Once computed, the value is cached.</remarks>
public override int GetHashCode()
{
if (_hash == -1)
{
int hash = 0;
for (ISeq s = seq(); s != null; s = s.next())
{
object e = s.first();
hash += Util.Hash(e);
}
_hash = hash;
}
return(_hash);
}
/// <summary>
/// Returns the key/value pair for this key.
/// </summary>
/// <param name="key">The key to retrieve</param>
/// <returns>The key/value pair for the key, or null if the key is not in the map.</returns>
public override IMapEntry entryAt(object key)
{
return((IMapEntry)_root.find(Util.Hash(key), key));
}
/// <summary>
/// Compute the hash code for the symbol.
/// </summary>
/// <returns>The hash code.</returns>
private int ComputeHashCode()
{
return(Util.HashCombine(_name.GetHashCode(), Util.Hash(_ns)));
}
