Crate implementing real associative arrays, also known as dictionaries.

Associative arrays behave just like indexed arrays, but use unique strings as indexes instead of integers.

In contrast to Hashmaps, associative arrays don't have the restriction of one to one mapping between keys and values. Also, the value doesn't need to be a string, but can be any generic type T.

This associative array implementation is built as a Trait implementation over std::vec::Vec, so all Vec methods are also available for a Dict object.

Insert time is O(n²), and retrieval time is O(log n). This means that it is far more efficient to query values than to insert them. If we need frequent inserts in big sets, it can be more efficient to implement a solution based on linked lists or binary heaps.

Examples

use dict::{ Dict, DictIface };

//create a dictionary of strings
let mut dict = Dict::<String>::new();
assert_eq!( dict.is_empty(), true );
assert_eq!( dict.len(), 0 );

// add an element "val" indexed by the key "key"
assert_eq!( dict.add( "key".to_string(), "val".to_string() ), true );
assert_eq!( dict.is_empty(), false );
assert_eq!( dict.len(), 1 );

// keys must be unique
assert_eq!( dict.add( "key".to_string()      , "other_val".to_string() ), false );
assert_eq!( dict.len(), 1 );
assert_eq!( dict.add( "other_key".to_string(), "other_val".to_string() ), true );
assert_eq!( dict.len(), 2 );

// we can access the value by its key string with get()
assert_eq!( dict.get( "key" ).unwrap(), "val" );
assert_eq!( dict.contains_key( "key" ), true );
assert_eq!( dict.remove_key( "key" ).unwrap(), "val" );
assert_eq!( dict.contains_key( "key" ), false );

More information

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