NAME

hashtable: Hash, HashNode - polymorphic hash table

SYNOPSIS

include "opt/powerman/hashtable/module/hashtable.m";
hashtable := load HashTable HashTable->PATH;

HashNode: adt[T]{
        key:    string;
        val:    T;
};
Hash: adt[T]{
        new:    fn(size:int):ref Hash[T];
        get:    fn(h:self ref Hash[T], key:string):T;
        set:    fn(h:self ref Hash[T], key:string, val:T);
        del:    fn(h:self ref Hash[T], key:string);
        all:    fn(h:self ref Hash[T]): list of ref HashNode[T];
};

DESCRIPTION

The hash module provides support for arrays that are indexed by keys of type string. The values may be any ref types including string (limitation of limbo's polymorphism). If you need to use numeric type as value then either create wrapper adt for it or use hash(2).

Hash.new creates and returns a new Hash with size slots. The hashing works best if size is a prime number.

Hash.get Search the table for an element with the given key and return the value found; return nil if none was found.

Hash.set Adds a new key/value pair to the table. If an element with the same key already exists, it will acquire the new value.

Hash.del Removes any element with the given key from the table. Do nothing if there is no such key in the table.

Hash.all Returns a list of all key/value pairs stored in the table.

EXAMPLE

include "opt/powerman/hashtable/module/hashtable.m";
        hashtable: HashTable;
        Hash: import hashtable;
Int: adt { i: int; };
HashOfString: type Hash[string];

hashtable = load HashTable HashTable->PATH;
hs  := Hash[string].new(7);
hi  := Hash[ref Int].new(7);
hhs := Hash[ref HashOfString].new(7);

hs.set("key", "value");
hi.set("key", ref Int(42));
hs1 := HashOfString.new(97);
hs2 := HashOfString.new(97);
hhs.set("first", hs1);
hhs.set("second", hs2);
hhs.get("first").set("key", "value");

SOURCE

/opt/powerman/hashtable/appl/lib/hashtable.b

SEE ALSO

hash(2)

BUGS

HASHTABLE(2 )

Rev:  Mon Mar 30 07:25:15 GMT 2015