191 lines
4.8 KiB
Prolog
191 lines
4.8 KiB
Prolog
/*
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This code implements hash-arrays.
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It requires the hash key to be a ground term.
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It relies on dynamic array code.
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*/
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:- source.
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:- yap_flag(unknown,error).
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:- style_check(all).
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:- module(b_hash, [ b_hash_new/1,
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b_hash_new/2,
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b_hash_new/4,
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b_hash_lookup/3,
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b_hash_update/3,
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b_hash_update/4,
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b_hash_insert_new/4,
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b_hash_insert/4
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]).
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:- use_module(library(terms), [ term_hash/4 ]).
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:- meta_predicate(b_hash_new(-,+,3,2)).
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array_default_size(2048).
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b_hash_new(hash(Keys, Vals, Size, N, _, _)) :-
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array_default_size(Size),
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array(Keys, Size),
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array(Vals, Size),
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create_mutable(0, N).
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b_hash_new(hash(Keys, Vals, Size, N, _, _), Size) :-
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array(Keys, Size),
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array(Vals, Size),
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create_mutable(0, N).
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b_hash_new(hash(Keys,Vals, Size, N, HashF, CmpF), Size, HashF, CmpF) :-
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array(Keys, Size),
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array(Vals, Size),
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create_mutable(0, N).
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b_hash_lookup(Key, Val, hash(Keys, Vals, Size, _, F, CmpF)):-
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hash_f(Key, Size, Index, F),
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fetch_key(Keys, Index, Size, Key, CmpF, ActualIndex),
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array_element(Vals, ActualIndex, Mutable),
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get_mutable(Val, Mutable).
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fetch_key(Keys, Index, Size, Key, CmpF, ActualIndex) :-
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array_element(Keys, Index, El),
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nonvar(El),
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(
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cmp_f(CmpF, El, Key)
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->
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Index = ActualIndex
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;
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I1 is (Index+1) mod Size,
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fetch_key(Keys, I1, Size, Key, CmpF, ActualIndex)
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).
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b_hash_update(Hash, Key, NewVal):-
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Hash = hash(Keys, Vals, Size, _, F, CmpF),
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hash_f(Key,Size,Index,F),
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fetch_key(Keys, Index, Size, Key, CmpF, ActualIndex),
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array_element(Vals, ActualIndex, Mutable),
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update_mutable(NewVal, Mutable).
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b_hash_update(Hash, Key, OldVal, NewVal):-
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Hash = hash(Keys, Vals, Size, _, F, CmpF),
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hash_f(Key,Size,Index,F),
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fetch_key(Keys, Index, Size, Key, CmpF, ActualIndex),
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array_element(Vals, ActualIndex, Mutable),
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get_mutable(OldVal, Mutable),
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update_mutable(NewVal, Mutable).
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b_hash_insert(Hash, Key, NewVal, NewHash):-
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Hash = hash(Keys, Vals, Size, N, F, CmpF),
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hash_f(Key,Size,Index,F),
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find_or_insert(Keys, Index, Size, N, CmpF, Vals, Key, NewVal, Hash, NewHash).
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find_or_insert(Keys, Index, Size, N, CmpF, Vals, Key, NewVal, Hash, NewHash) :-
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array_element(Keys, Index, El),
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(
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var(El)
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->
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add_element(Keys, Index, Size, N, Vals, Key, NewVal, Hash, NewHash)
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;
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cmp_f(CmpF, El, Key)
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->
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% do rb_update
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array_element(Vals, Index, Mutable),
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update_mutable(NewVal, Mutable)
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;
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I1 is (Index+1) mod Size,
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find_or_insert(Keys, I1, Size, N, CmpF, Vals, Key, NewVal, Hash, NewHash)
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).
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b_hash_insert_new(Hash, Key, NewVal, NewHash):-
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Hash = hash(Keys, Vals, Size, N, F, CmpF),
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hash_f(Key,Size,Index,F),
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find_or_insert_new(Keys, Index, Size, N, CmpF, Vals, Key, NewVal, Hash, NewHash).
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find_or_insert_new(Keys, Index, Size, N, CmpF, Vals, Key, NewVal, Hash, NewHash) :-
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array_element(Keys, Index, El),
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(
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var(El)
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->
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add_element(Keys, Index, Size, N, Vals, Key, NewVal, Hash, NewHash)
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;
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cmp_f(CmpF, El, Key)
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->
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fail
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;
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I1 is (Index+1) mod Size,
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find_or_insert_new(Keys, I1, Size, N, CmpF, Vals, Key, NewVal, Hash, NewHash)
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).
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add_element(Keys, Index, Size, N, Vals, Key, NewVal, Hash, NewHash) :-
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get_mutable(NEls, N),
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NN is NEls+1,
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update_mutable(NN, N),
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(
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NN > Size/3
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->
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expand_array(Hash, NewHash)
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;
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Hash = NewHash
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),
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array_element(Keys, Index, Key),
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update_mutable(NN, N),
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array_element(Vals, Index, Mutable),
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create_mutable(NewVal, Mutable).
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expand_array(Hash, hash(NewKeys, NewVals, NewSize, X, F, CmpF)) :-
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Hash = hash(Keys, Vals, Size, X, F, CmpF),
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new_size(Size, NewSize),
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array(NewKeys, NewSize),
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array(NewVals, NewSize),
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copy_hash_table(Size, Keys, Vals, F, NewSize, NewKeys, NewVals).
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new_size(Size, NewSize) :-
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Size > 1048576, !,
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NewSize is Size+1048576.
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new_size(Size, NewSize) :-
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NewSize is Size*2.
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copy_hash_table(0, _, _, _, _, _, _) :- !.
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copy_hash_table(I1, Keys, Vals, F, Size, NewKeys, NewVals) :-
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I is I1-1,
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array_element(Keys, I, Key),
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nonvar(Key), !,
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array_element(Vals, I, Val),
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insert_el(Key, Val, Size, F, NewKeys, NewVals),
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copy_hash_table(I, Keys, Vals, F, Size, NewKeys, NewVals).
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copy_hash_table(I1, Keys, Vals, F, Size, NewKeys, NewVals) :-
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I is I1-1,
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copy_hash_table(I, Keys, Vals, F, Size, NewKeys, NewVals).
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insert_el(Key, Val, Size, F, NewKeys, NewVals) :-
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hash_f(Key,Size,Index, F),
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find_free(Index, Size, NewKeys, TrueIndex),
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array_element(NewKeys, TrueIndex, Key),
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array_element(NewVals, TrueIndex, Val).
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find_free(Index, Size, Keys, NewIndex) :-
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array_element(Keys, Index, El),
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(
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var(El)
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->
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NewIndex = Index
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;
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I1 is (Index+1) mod Size,
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find_free(I1, Size, Keys, NewIndex)
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).
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hash_f(Key, Size, Index, F) :-
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var(F), !,
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term_hash(Key,-1,Size,Index).
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hash_f(Key, Size, Index, F) :-
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call(F, Key, Size, Index).
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cmp_f(F, A, B) :-
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var(F), !,
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A == B.
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cmp_f(F, A, B) :-
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call(F, A, B).
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