## unt-hashtable.pkg
## AUTHOR: John Reppy
## Bell Labs
## Murray Hill, NJ 07974
## jhr@research.bell-labs.com
# Compiled by:
# src/lib/std/standard.lib# A specialization of the hashtable generic to word keys.
### "You can always count on Americans
### to do the right thing -- after they've
### tried everything else."
###
### -- Winston Churchill
package unt_hashtable
:
Typelocked_Hashtable # Typelocked_Hashtable is from src/lib/src/typelocked-hashtable.apiwhere
key::Hash_Key == Unt
=
package {
package key {
Hash_Key = Unt;
fun same_key (a: Unt, b)
=
a == b;
fun hash_value a
=
a;
};
include key;
package htrep= hashtable_representation; # hashtable_representation is from src/lib/src/hashtable-rep.pkg Hashtable X
=
HASHTABLE {
not_found_exception: Exception,
table: Ref( htrep::Table( Hash_Key, X) ),
n_items: Ref( Int )
};
fun index (i, size)
=
unt::to_int_x (unt::bitwise_and (i, unt::from_int size - 0u1));
# Create a new table.
# The int is a size hint and the exception
# is to be raised by find.
#
fun make_hashtable { size_hint, not_found_exception }
=
HASHTABLE
{
not_found_exception,
table => REF (htrep::alloc size_hint),
n_items => REF 0
};
# Remove all elements from the table:
#
fun clear (HASHTABLE { table, n_items, ... } )
=
{ htrep::clear *table;
n_items := 0;
};
# Insert an item. If the key already has an item associated with it,
# then the old item is discarded.
#
fun set (my_table as HASHTABLE { table, n_items, ... } ) (key, item)
=
{
arr = *table;
size = rw_vector::length arr;
hash = hash_value key;
index = index (hash, size);
fun get htrep::NIL
=>
{
rw_vector::set (arr, index, htrep::BUCKET (hash, key, item, rw_vector::get (arr, index)));
n_items := *n_items + 1;
htrep::grow_table_if_needed (table, *n_items);
htrep::NIL;
};
get (htrep::BUCKET (h, k, v, r))
=>
if (hash == h
and same_key (key, k))
htrep::BUCKET (hash, key, item, r);
else
case (get r)
htrep::NIL => htrep::NIL;
rest => htrep::BUCKET (h, k, v, rest);
esac;
fi;
end;
case (get (rw_vector::get (arr, index)))
htrep::NIL => ();
b => rw_vector::set (arr, index, b);
esac;
};
# Return TRUE if the key is in
# the domain of the table:
#
fun contains_key (HASHTABLE { table, ... } ) key
=
get' (rw_vector::get (arr, index))
where
arr = *table;
hash = hash_value key;
index = index (hash, rw_vector::length arr);
fun get' htrep::NIL
=>
FALSE;
get' (htrep::BUCKET (h, k, v, r))
=>
((hash == h) and same_key (key, k)) or
get' r;
end;
end;
# Find an item.
# The table's exception is raised
# if the item doesn't exist:
#
fun get (HASHTABLE { table, not_found_exception, ... } ) key
=
get' (rw_vector::get (arr, index))
where
arr = *table;
hash = hash_value key;
index = index (hash, rw_vector::length arr);
fun get' htrep::NIL
=>
raise exception not_found_exception;
get' (htrep::BUCKET (h, k, v, r))
=>
if (hash == h
and same_key (key, k))
v;
else
get' r;
fi;
end;
end;
# Look up an item.
# Return NULL if the item doesn't exist:
#
fun find (HASHTABLE { table, ... } ) key
=
get' (rw_vector::get (arr, index))
where
arr = *table;
size = rw_vector::length arr;
hash = hash_value key;
index = index (hash, size);
fun get' htrep::NIL
=>
NULL;
get' (htrep::BUCKET (h, k, v, r))
=>
if (hash == h and same_key (key, k)) THE v;
else get' r;
fi;
end;
end;
# Remove an item.
# The table's exception is raised
# if the item doesn't exist.
#
fun remove (HASHTABLE { not_found_exception, table, n_items } ) key
=
{
arr = *table;
size = rw_vector::length arr;
hash = hash_value key;
index = index (hash, size);
fun get htrep::NIL
=>
raise exception not_found_exception;
get (htrep::BUCKET (h, k, v, r))
=>
if (hash == h and same_key (key, k))
(v, r);
else
my (item, r') = get r;
(item, htrep::BUCKET (h, k, v, r'));
fi;
end;
my (item, bucket) = get (rw_vector::get (arr, index));
rw_vector::set (arr, index, bucket);
n_items := *n_items - 1;
item;
};
# Return the number of items in the table:
#
fun vals_count (HASHTABLE { n_items, ... } ) = *n_items;
# Return a list of the items in the table:
#
fun vals_list (HASHTABLE { table => REF arr, n_items, ... } )
=
htrep::vals_list (arr, n_items);
fun keyvals_list (HASHTABLE { table => REF arr, n_items, ... } )
=
htrep::keyvals_list (arr, n_items);
# Apply a function to the entries of the table:
#
fun keyed_apply f (HASHTABLE { table, ... } ) = htrep::keyed_apply f *table;
fun apply f (HASHTABLE { table, ... } ) = htrep::apply f *table;
# Map a table to a new table
# that has the same keys and exception:
#
fun keyed_map f (HASHTABLE { table, n_items, not_found_exception } )
=
HASHTABLE {
table => REF (htrep::keyed_map f *table),
n_items => REF *n_items,
not_found_exception
};
fun map f (HASHTABLE { table, n_items, not_found_exception } )
=
HASHTABLE {
table => REF (htrep::map f *table),
n_items => REF *n_items,
not_found_exception
};
# Fold a function over the entries of the table:
#
fun foldi f init (HASHTABLE { table, ... } ) = htrep::foldi f init *table;
fun fold f init (HASHTABLE { table, ... } ) = htrep::fold f init *table;
# Modify the hashtable items in place:
#
fun modifyi f (HASHTABLE { table, ... } ) = htrep::modifyi f *table;
fun modify f (HASHTABLE { table, ... } ) = htrep::modify f *table;
# Remove any hashtable items
# that do not satisfy the given
# predicate.
#
fun keyed_filter prior (HASHTABLE { table, n_items, ... } )
=
n_items := htrep::keyed_filter prior *table;
fun filter prior (HASHTABLE { table, n_items, ... } )
=
n_items := htrep::filter prior *table;
# Create a copy of a hashtable:
#
fun copy (HASHTABLE { table, n_items, not_found_exception } )
=
HASHTABLE {
table => REF (htrep::copy *table),
n_items => REF *n_items,
not_found_exception
};
# Return a list of the sizes of the various buckets.
# This is to allow users to gauge the quality of their
# hashing function.
#
fun bucket_sizes (HASHTABLE { table, ... } )
=
htrep::bucket_sizes *table;
}; # typelocked_hashtable_g