shithub: purgatorio

ref: 75c92428225428c8fde2d015f010e608a0b12f1d
dir: purgatorio/man/2/hash

.TH HASH 2
.SH NAME
hash, HashTable \- hash table
.SH SYNOPSIS
.EX
include "hash.m";
hash := load Hash Hash->PATH;

new: fn(size:int):ref HashTable;

HashTable: adt{
	insert: fn(h:self ref HashTable, key:string, val:HashVal);
	find: fn(h:self ref HashTable, key:string):ref HashVal;
	delete: fn(h:self ref HashTable, key:string);
	all: fn(h:self ref HashTable): list of HashNode;
};
HashVal: adt{
	i: int;
	r: real;
	s: string;
};
HashNode: adt{
	key: string;
	val: ref HashVal;
};
fun1, fun2: fn(s:string, n:int):int;
.EE
.SH DESCRIPTION
The hash module provides support for arrays that are indexed by keys of type
.BR string .

The values may be any combination of
.BR int ,
.BR real ,
or
.BR string .
.B New
creates and returns a new
.B HashTable
with
.I size
slots. The hashing works best if
.I size
is a prime number. The
.B HashVal
adt contains the data values of the hash.
The
.B HashNode
adt contains the key/value pair for each element in the table.
.TP
.IB ht .insert( "key, value" )
Adds a new
.IR key / value
pair to the table.
If an element with the same
.I key
already exists,
it will acquire the new
.IR value .
.TP
.IB ht .find( key )
Search the table for an element with the given
.I key
and return the value found; return nil if none was found.
.TP
.IB ht .delete( key )
Removes any element with the given
.I key
from the table.
.TP
.IB ht .all()
Returns a list of all key/value pairs stored in the table.
.PP
.B Fun1
and
.B fun2
provide access to two different string hashing functions.
.B Fun1
is the function used internally;
.B fun2
is the same as that used in the Limbo compiler.
They each compute the hash value of 
.I s
and return a value between 0 and
.IR n \-1.
.SH SOURCE
.B /appl/lib/hash.b
.SH BUGS
.B HashVal
should really be a
.BR pick .