;;; Ikarus Scheme -- A compiler for R6RS Scheme.
;;; Copyright (C) 2006,2007,2008  Abdulaziz Ghuloum
;;; 
;;; This program is free software: you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License version 3 as
;;; published by the Free Software Foundation.
;;; 
;;; This program is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;;; General Public License for more details.
;;; 
;;; You should have received a copy of the GNU General Public License
;;; along with this program.  If not, see <http://www.gnu.org/licenses/>.


(library (ikarus hash-tables)
  (export make-eq-hashtable hashtable-ref hashtable-set! hashtable?
          hashtable-size hashtable-delete! hashtable-contains?
          hashtable-update! hashtable-keys hashtable-mutable?
          hashtable-clear! hashtable-entries hashtable-copy
          string-hash string-ci-hash symbol-hash)
  (import 
    (ikarus system $pairs)
    (ikarus system $vectors)
    (ikarus system $tcbuckets)
    (ikarus system $fx)
    (except (ikarus) make-eq-hashtable hashtable-ref hashtable-set! hashtable?
            hashtable-size hashtable-delete! hashtable-contains?
            hashtable-update! hashtable-keys hashtable-mutable?
            hashtable-clear! hashtable-entries hashtable-copy
            string-hash string-ci-hash symbol-hash))

  (define-struct hasht (vec count tc mutable?))

  ;;; directly from Dybvig's paper
  (define tc-pop
    (lambda (tc)
      (let ([x ($car tc)])
        (if (eq? x ($cdr tc))
            #f
            (let ([v ($car x)])
              ($set-car! tc ($cdr x))
              ($set-car! x #f)
              ($set-cdr! x #f)
              v)))))

  ;;; assq-like lookup
  (define direct-lookup 
    (lambda (x b)
      (if (fixnum? b)
          #f
          (if (eq? x ($tcbucket-key b))
              b
              (direct-lookup x ($tcbucket-next b))))))

  (define rehash-lookup
    (lambda (h tc x)
      (cond
        [(tc-pop tc) =>
         (lambda (b)
           (if (eq? ($tcbucket-next b) #f)
               (rehash-lookup h tc x)
               (begin
                 (re-add! h b)
                 (if (eq? x ($tcbucket-key b))
                     b
                     (rehash-lookup h tc x)))))]
        [else #f])))

  (define get-bucket-index
    (lambda (b)
      (let ([next ($tcbucket-next b)])
        (if (fixnum? next)
            next
            (get-bucket-index next)))))

  (define replace!
    (lambda (lb x y)
      (let ([n ($tcbucket-next lb)])
        (cond
          [(eq? n x) 
           ($set-tcbucket-next! lb y)
           (void)]
          [else
           (replace! n x y)]))))

  (define re-add! 
    (lambda (h b)
      (let ([vec (hasht-vec h)]
            [next ($tcbucket-next b)])
        ;;; first remove it from its old place
        (let ([idx 
               (if (fixnum? next)
                   next
                   (get-bucket-index next))])
          (let ([fst ($vector-ref vec idx)])
            (cond
              [(eq? fst b) 
               ($vector-set! vec idx next)]
              [else 
               (replace! fst b next)])))
        ;;; reset the tcbucket-tconc FIRST
        ($set-tcbucket-tconc! b (hasht-tc h))
        ;;; then add it to the new place
        (let ([k ($tcbucket-key b)])
          (let ([ih (pointer-value k)])
            (let ([idx ($fxlogand ih ($fx- ($vector-length vec) 1))])
              (let ([n ($vector-ref vec idx)])
                ($set-tcbucket-next! b n)
                ($vector-set! vec idx b)
                (void))))))))

  (define (get-bucket h x)
    (let ([pv (pointer-value x)]
          [vec (hasht-vec h)])
      (let ([ih pv])
        (let ([idx ($fxlogand ih ($fx- ($vector-length vec) 1))])
          (let ([b ($vector-ref vec idx)])
            (or (direct-lookup x b)
                (rehash-lookup h (hasht-tc h) x)))))))

  (define (get-hash h x v)
    (cond
      [(get-bucket h x) =>
       (lambda (b) ($tcbucket-val b))]
      [else v]))

  (define (in-hash? h x)
    (and (get-bucket h x) #t))

  (define (del-hash h x)
    (define unlink! 
      (lambda (h b)
        (let ([vec (hasht-vec h)]
              [next ($tcbucket-next b)])
          ;;; first remove it from its old place
          (let ([idx 
                 (if (fixnum? next)
                     next
                     (get-bucket-index next))])
            (let ([fst ($vector-ref vec idx)])
              (cond
                [(eq? fst b) 
                 ($vector-set! vec idx next)]
                [else 
                 (replace! fst b next)])))
          ;;; set next to be #f, denoting, not in table
          ($set-tcbucket-next! b #f))))
    (cond
      [(get-bucket h x) => 
       (lambda (b) 
         (unlink! h b)
         ;;; don't forget the count.
         (set-hasht-count! h (- (hasht-count h) 1)))]))

  (define put-hash!
    (lambda (h x v)
      (let ([pv (pointer-value x)]
            [vec (hasht-vec h)])
        (let ([ih pv])
          (let ([idx ($fxlogand ih ($fx- ($vector-length vec) 1))])
            (let ([b ($vector-ref vec idx)])
              (cond
                [(or (direct-lookup x b) (rehash-lookup h (hasht-tc h) x))
                 =>
                 (lambda (b) 
                   ($set-tcbucket-val! b v)
                   (void))]
                [else 
                 (let ([bucket
                        ($make-tcbucket (hasht-tc h) x v ($vector-ref vec idx))])
                   (if ($fx= (pointer-value x) pv)
                       ($vector-set! vec idx bucket)
                       (let* ([ih (pointer-value x)]
                              [idx 
                               ($fxlogand ih ($fx- ($vector-length vec) 1))])
                         ($set-tcbucket-next! bucket ($vector-ref vec idx))
                         ($vector-set! vec idx bucket))))
                 (let ([ct (hasht-count h)])
                   (set-hasht-count! h ($fxadd1 ct))
                   (when ($fx> ct ($vector-length vec))
                     (enlarge-table h)))])))))))
          
  (define (update-hash! h x proc default)
    (cond
      [(get-bucket h x) =>
       (lambda (b) ($set-tcbucket-val! b (proc ($tcbucket-val b))))]
      [else (put-hash! h x (proc default))]))

  (define insert-b
    (lambda (b vec mask)
      (let* ([x ($tcbucket-key b)]
             [pv (pointer-value x)]
             [ih pv]
             [idx ($fxlogand ih mask)]
             [next ($tcbucket-next b)])
        ($set-tcbucket-next! b ($vector-ref vec idx))
        ($vector-set! vec idx b)
        (unless (fixnum? next)
          (insert-b next vec mask)))))

  (define move-all
    (lambda (vec1 i n vec2 mask)
      (unless ($fx= i n)
        (let ([b ($vector-ref vec1 i)])
          (unless (fixnum? b)
            (insert-b b vec2 mask))
          (move-all vec1 ($fxadd1 i) n vec2 mask)))))

  (define enlarge-table
    (lambda (h)
      (let* ([vec1 (hasht-vec h)]
             [n1 ($vector-length vec1)]
             [n2 ($fxsll n1 1)]
             [vec2 (make-base-vec n2)])
        (move-all vec1 0 n1 vec2 ($fx- n2 1))
        (set-hasht-vec! h vec2))))

  (define init-vec
    (lambda (v i n)
      (if ($fx= i n)
          v
          (begin
            ($vector-set! v i i)
            (init-vec v ($fxadd1 i) n)))))

  (define make-base-vec
    (lambda (n)
      (init-vec (make-vector n) 0 n)))

  (define (clear-hash! h) 
    (let ([v (hasht-vec h)])
      (init-vec v 0 (vector-length v)))
    (set-hasht-tc! h 
      (let ([x (cons #f #f)])
        (cons x x)))
    (set-hasht-count! h 0))

  (define (get-keys h)
    (let ([v (hasht-vec h)] [n (hasht-count h)])
      (let ([kv (make-vector n)])
        (let f ([i ($fxsub1 n)] [j ($fxsub1 (vector-length v))] [kv kv] [v v])
          (cond
            [($fx= i -1) kv]
            [else 
             (let ([b ($vector-ref v j)])
               (if (fixnum? b) 
                   (f i ($fxsub1 j) kv v)
                   (f (let f ([i i] [b b] [kv kv])
                        ($vector-set! kv i ($tcbucket-key b))
                        (let ([b ($tcbucket-next b)]
                              [i ($fxsub1 i)])
                          (cond
                            [(fixnum? b) i]
                            [else (f i b kv)])))
                      ($fxsub1 j) kv v)))])))))

  (define (get-entries h)
    (let ([v (hasht-vec h)] [n (hasht-count h)])
      (let ([kv (make-vector n)] [vv (make-vector n)])
        (let f ([i ($fxsub1 n)] [j ($fxsub1 (vector-length v))] [kv kv] [vv vv] [v v])
          (cond
            [($fx= i -1) (values kv vv)]
            [else 
             (let ([b ($vector-ref v j)])
               (if (fixnum? b) 
                   (f i ($fxsub1 j) kv vv v)
                   (f (let f ([i i] [b b] [kv kv] [vv vv])
                        ($vector-set! kv i ($tcbucket-key b))
                        ($vector-set! vv i ($tcbucket-val b))
                        (let ([b ($tcbucket-next b)]
                              [i ($fxsub1 i)])
                          (cond
                            [(fixnum? b) i]
                            [else (f i b kv vv)])))
                      ($fxsub1 j) kv vv v)))])))))

  (define (hasht-copy h mutable?)
    (define (dup-hasht h mutable? n)
      (let ([x (cons #f #f)])
        (let ([tc (cons x x)])
          (make-hasht (make-base-vec n) 0 tc mutable?))))
    (let ([v (hasht-vec h)] [n (hasht-count h)])
      (let ([r (dup-hasht h mutable? (vector-length v))])
        (let f ([i ($fxsub1 n)] [j ($fxsub1 (vector-length v))] [r r] [v v])
          (cond
            [($fx= i -1) r]
            [else 
             (let ([b ($vector-ref v j)])
               (if (fixnum? b) 
                   (f i ($fxsub1 j) r v)
                   (f (let f ([i i] [b b] [r r])
                        (put-hash! r ($tcbucket-key b) ($tcbucket-val b))
                        (let ([b ($tcbucket-next b)] [i ($fxsub1 i)])
                          (cond
                            [(fixnum? b) i]
                            [else (f i b r)])))
                      ($fxsub1 j) r v)))])))))

  ;;; public interface
  (define (hashtable? x) (hasht? x))

  (define make-eq-hashtable
    (case-lambda
      [()
       (let ([x (cons #f #f)])
         (let ([tc (cons x x)])
           (make-hasht (make-base-vec 32) 0 tc #t)))]
      [(k) 
       (if (and (or (fixnum? k) (bignum? k))
                (>= k 0))
           (make-eq-hashtable)
           (die 'make-eq-hashtable
             "invalid initial capacity" k))]))

  (define hashtable-ref
    (lambda (h x v)
      (if (hasht? h)
          (get-hash h x v)
          (die 'hashtable-ref "not a hash table" h))))

  (define hashtable-contains?
    (lambda (h x)
      (if (hasht? h)
          (in-hash? h x)
          (die 'hashtable-contains? "not a hash table" h))))

  (define hashtable-set!
    (lambda (h x v)
      (if (hasht? h)
          (if (hasht-mutable? h) 
              (put-hash! h x v)
              (die 'hashtable-set! "hashtable is immutable" h))
          (die 'hashtable-set! "not a hash table" h))))

  (define hashtable-update!
    (lambda (h x proc default)
      (if (hasht? h)
          (if (hasht-mutable? h)
              (if (procedure? proc)
                  (update-hash! h x proc default)
                  (die 'hashtable-update! "not a procedure" proc))
              (die 'hashtable-update! "hashtable is immutable" h))
          (die 'hashtable-update! "not a hash table" h))))

  (define hashtable-size
    (lambda (h)
      (if (hasht? h) 
          (hasht-count h)
          (die 'hashtable-size "not a hash table" h))))

  (define hashtable-delete!
    (lambda (h x) 
      ;;; FIXME: should shrink table if number of keys drops below
      ;;; (sqrt (vector-length (hasht-vec h)))
      (if (hasht? h)
          (if (hasht-mutable? h)
              (del-hash h x)
              (die 'hashtable-delete! "hashtable is immutable" h))
          (die 'hashtable-delete! "not a hash table" h))))

  (define (hashtable-entries h)
    (if (hasht? h) 
        (get-entries h)
        (die 'hashtable-entries "not a hash table" h)))

  (define (hashtable-keys h)
    (if (hasht? h) 
        (get-keys h)
        (die 'hashtable-keys "not a hash table" h)))

  (define (hashtable-mutable? h)
    (if (hasht? h) 
        (hasht-mutable? h)
        (die 'hashtable-mutable? "not a hash table" h)))

  (define (hashtable-clear! h)
    (if (hasht? h) 
        (if (hasht-mutable? h)
            (clear-hash! h)
            (die 'hashtable-clear! "hashtable is immutable" h))
        (die 'hashtable-clear! "not a hash table" h)))

  (define hashtable-copy 
    (case-lambda
      [(h) 
       (if (hasht? h)
           (if (hasht-mutable? h) 
               (hasht-copy h #f)
               h)
           (die 'hashtable-copy "not a hash table" h))]
      [(h mutable?)
       (if (hasht? h)
           (if (or mutable? (hasht-mutable? h))
               (hasht-copy h (and mutable? #t))
               h)
           (die 'hashtable-copy "not a hash table" h))]))

  (define (string-hash s)
    (if (string? s) 
        (foreign-call "ikrt_string_hash" s)
        (die 'string-hash "not a string" s)))

  (define (string-ci-hash s)
    (if (string? s) 
        (foreign-call "ikrt_string_hash" 
          (string-foldcase s))
        (die 'string-ci-hash "not a string" s)))

  (define (symbol-hash s)
    (if (symbol? s) 
        (foreign-call "ikrt_string_hash" (symbol->string s))
        (die 'symbol-hash "not a symbol" s)))

)