This library provides a dictionary (also know as associative array, map, or symbol table) protocol and binary tree, AVL tree, and Red–Black tree implementations. The different representations of a dictionary should be regarded as opaque terms and only accessed using the library predicates.
Open the ../../docs/library_index.html#dictionaries link in a web browser.
To load all entities in this library, load the
| ?- logtalk_load(dictionaries(loader)).
To test this library predicates, load the
| ?- logtalk_load(dictionaries(tester)).
First, select the dictionary implementation that you want to use. For
cases where the number of elements is relatively small and performance
is not critical,
bintree can be a good choice. For other cases,
rbtree are likely better choices. If you want to
compare the performance of the implementations, either define an object
alias or use a
uses/2 directive so that you can switch between
implementations by simply changing the alias definition or the first
argument of the directive. Note that you can switch between
implementations at runtime without code changes by using a parameter
variable in the first argument of a
Dictionary keys should preferable be ground terms. If the keys contain variables, the user must ensure that any instantiation of those variables when calling this library predicates will not affect the key ordering.
To create a new dictionary, you can use the
new/1 predicate. For
| ?- avltree::new(Dictionary). Dictionary = ... yes
You can also create a new dictionary from a list of key-value pairs by
as_dictionary/2 predicate. For example:
| ?- avltree::as_dictionary([a-1,c-3,b-2], Dictionary). Dictionary = ... yes
Several predicates are provided for inserting key-value pairs, lookup key-value pairs updating the value associated with a key, and deleting key-value pairs. For example:
| ?- avltree::( new(Dictionary0), insert(Dictionary0, a, 1, Dictionary1), update(Dictionary1, a, 2, Dictionary2), lookup(a, Value, Dictionary2) ). Dictionary0 = ..., Dictionary1 = ..., Dictionary2 = ..., Value = 2 yes
For details on these and other provided predicates, consult the library API documentation.
The AVL tree implementation is an adaptation to Logtalk of the
SWI-Prolog library authored by R.A.O’Keefe, L.Damas, V.S.Costa, Glenn
Burgess, Jiri Spitz, and Jan Wielemaker. Additional predicates authored
by Paulo Moura.
The Red–Black tree implementation is an adaptation to Logtalk of the
rbtrees Prolog library authored by Vitor Santos Costa.