X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Fhash-table.lisp;h=c352a17a7f819b4df7819988b70b97130d0fbbcb;hb=860543cc7ba0266e41e1d41ac9b6a208f3795f1a;hp=76a29780f333656097fabbd8b6dffc84904c5b90;hpb=cea4896b2482b7b2b429c1631d774b4cfbc0efba;p=sbcl.git diff --git a/src/code/hash-table.lisp b/src/code/hash-table.lisp index 76a2978..c352a17 100644 --- a/src/code/hash-table.lisp +++ b/src/code/hash-table.lisp @@ -12,64 +12,37 @@ (in-package "SB!IMPL") -;;; an internal tag for marking empty slots -;;; -;;; CMU CL 18b used :EMPTY for this purpose, which was somewhat nasty -;;; since it's easily accessible to the user, so that e.g. -;;; (DEFVAR *HT* (MAKE-HASH-TABLE)) -;;; (SETF (GETHASH :EMPTY *HT*) :EMPTY) -;;; (MAPHASH (LAMBDA (K V) (FORMAT T "~&~S ~S~%" K V))) -;;; gives no output -- oops! -;;; -;;; Note that as of version 0.6.6 there's a dependence in the gencgc.c -;;; code on this value being a symbol. (This is only one of many nasty -;;; dependencies between that code and this, alas.) -(defconstant +empty-ht-slot+ '%empty-ht-slot%) -;;; KLUDGE: Using a private symbol still leaves us vulnerable to users -;;; getting nonconforming behavior by messing around with -;;; DO-ALL-SYMBOLS. That seems like a fairly obscure problem, so for -;;; now we just don't worry about it. If for some reason it becomes -;;; worrisome and the magic value needs replacement: -;;; * The replacement value needs to be LOADable with EQL preserved, -;;; so that macroexpansion for WITH-HASH-TABLE-ITERATOR will work -;;; when compiled into a file and loaded back into SBCL. -;;; (Thus, just uninterning %EMPTY-HT-SLOT% doesn't work.) -;;; * The replacement value needs to be acceptable to the -;;; low-level gencgc.lisp hash table scavenging code. -;;; * The change will break binary compatibility, since comparisons -;;; against the value used at the time of compilation are wired -;;; into FASL files. -;;; -- WHN 20000622 - ;;; HASH-TABLE is implemented as a STRUCTURE-OBJECT. (sb!xc:defstruct (hash-table (:constructor %make-hash-table)) - ;; The type of hash table this is. Only used for printing and as part of - ;; the exported interface. - (test (required-argument) :type symbol :read-only t) - ;; The function used to compare two keys. Returns T if they are the same - ;; and NIL if not. - (test-fun (required-argument) :type function :read-only t) - ;; The function used to compute the hashing of a key. Returns two values: - ;; the index hashing and T if that might change with the next GC. - (hash-fun (required-argument) :type function :read-only t) - ;; How much to grow the hash table by when it fills up. If an index, then - ;; add that amount. If a floating point number, then multiple it by that. - (rehash-size (required-argument) :type (or index (single-float (1.0))) + ;; The type of hash table this is. Only used for printing and as + ;; part of the exported interface. + (test (missing-arg) :type symbol :read-only t) + ;; The function used to compare two keys. Returns T if they are the + ;; same and NIL if not. + (test-fun (missing-arg) :type function :read-only t) + ;; The function used to compute the hashing of a key. Returns two + ;; values: the index hashing and T if that might change with the + ;; next GC. + (hash-fun (missing-arg) :type function :read-only t) + ;; how much to grow the hash table by when it fills up. If an index, + ;; then add that amount. If a floating point number, then multiply + ;; it by that. + (rehash-size (missing-arg) :type (or index (single-float (1.0))) :read-only t) - ;; How full the hash table has to get before we rehash. - (rehash-threshold (required-argument) :type (single-float (0.0) 1.0) - :read-only t) - ;; The number of entries before a rehash, just the one less than the + ;; how full the hash table has to get before we rehash + (rehash-threshold (missing-arg) :type (single-float (0.0) 1.0) :read-only t) + ;; The number of entries before a rehash, just one less than the ;; size of the next-vector, hash-vector, and half the size of the ;; kv-vector. - (rehash-trigger (required-argument) :type index) + (rehash-trigger (missing-arg) :type index) ;; The current number of entries in the table. (number-entries 0 :type index) ;; The Key-Value pair vector. - (table (required-argument) :type simple-vector) - ;; True if this is a weak hash table, meaning that key->value mappings will - ;; disappear if there are no other references to the key. Note: this only - ;; matters if the hash function indicates that the hashing is EQ based. + (table (missing-arg) :type simple-vector) + ;; True if this is a weak hash table, meaning that key->value + ;; mappings will disappear if there are no other references to the + ;; key. Note: this only matters if the hash function indicates that + ;; the hashing is EQ based. (weak-p nil :type (member t nil)) ;; Index into the next-vector, chaining together buckets that need ;; to be rehashed because their hashing is EQ based and the key has @@ -80,17 +53,16 @@ (next-free-kv 0 :type index) ;; The index vector. This may be larger than the hash size to help ;; reduce collisions. - (index-vector (required-argument) - :type (simple-array (unsigned-byte 32) (*))) + (index-vector (missing-arg) :type (simple-array (unsigned-byte 32) (*))) ;; This table parallels the KV vector, and is used to chain together ;; the hash buckets, the free list, and the values needing rehash, a ;; slot will only ever be in one of these lists. - (next-vector (required-argument) :type (simple-array (unsigned-byte 32) (*))) + (next-vector (missing-arg) :type (simple-array (unsigned-byte 32) (*))) ;; This table parallels the KV table, and can be used to store the ;; hash associated with the key, saving recalculation. Could be ;; useful for EQL, and EQUAL hash tables. This table is not needed ;; for EQ hash tables, and when present the value of #x8000000 - ;; represents EQ-based hashing on the respective Key. + ;; represents EQ-based hashing on the respective key. (hash-vector nil :type (or null (simple-array (unsigned-byte 32) (*))))) (defmacro-mundanely with-hash-table-iterator ((function hash-table) &body body) @@ -117,8 +89,8 @@ (let ((key (aref kv-vector (* 2 index))) (value (aref kv-vector (1+ (* 2 index))))) (incf index) - (unless (and (eq key '#.+empty-ht-slot+) - (eq value '#.+empty-ht-slot+)) + (unless (and (eq key +empty-ht-slot+) + (eq value +empty-ht-slot+)) (return (values t key value)))))))) #',function)))) (macrolet ((,function () '(funcall ,n-function)))