class Hash(K, V)
Overview
A Hash
represents a collection of key-value mappings, similar to a dictionary.
Main operations are storing a key-value mapping (#[]=
) and
querying the value associated to a key (#[]
). Key-value mappings can also be
deleted (#delete
).
Keys are unique within a hash. When adding a key-value mapping with a key that
is already in use, the old value will be forgotten.
# Create a new Hash for mapping String to Int32
hash = Hash(String, Int32).new
hash["one"] = 1
hash["two"] = 2
hash["one"] # => 1
Hash literals
can also be used to create a Hash
:
{"one" => 1, "two" => 2}
Implementation is based on an open hash table.
Two objects refer to the same hash key when their hash value (Object#hash
)
is identical and both objects are equal to each other (Object#==
).
Enumeration follows the order that the corresponding keys were inserted.
NOTE When using mutable data types as keys, changing the value of a key after
it was inserted into the Hash
may lead to undefined behaviour. This can be
restored by re-indexing the hash with #rehash
.
Included Modules
- Enumerable({K, V})
- Iterable({K, V})
Defined in:
to_con.crany.cr
from_con.cr
Class Method Summary
Instance Method Summary
Instance methods inherited from class Reference
==(other : CON::Any)
==
Instance methods inherited from class Object
===(other : CON::Any)
===,
from_con(con : String | IO)
from_con,
to_con(io : IO)to_con to_con, to_pretty_con(indent : String = " ")
to_pretty_con(io : IO, indent : String = " ") to_pretty_con