diff options
| -rw-r--r-- | stdlib/weak.ml | 2 | ||||
| -rw-r--r-- | stdlib/weak.mli | 24 |
2 files changed, 21 insertions, 5 deletions
diff --git a/stdlib/weak.ml b/stdlib/weak.ml index 7177f2eb9f..b57cc64cc3 100644 --- a/stdlib/weak.ml +++ b/stdlib/weak.ml @@ -24,6 +24,8 @@ external set : 'a t -> int -> 'a option -> unit = "weak_set";; external get: 'a t -> int -> 'a option = "weak_get";; +external get_copy: 'a t -> int -> 'a option = "weak_get_copy";; + external check: 'a t -> int -> bool = "weak_check";; let fill ar ofs len x = diff --git a/stdlib/weak.mli b/stdlib/weak.mli index 26192608a3..b326dba383 100644 --- a/stdlib/weak.mli +++ b/stdlib/weak.mli @@ -16,15 +16,16 @@ type 'a t;; (* The type of arrays of weak pointers (weak arrays). A weak - pointer is an object that the garbage collector may erase at + pointer is a value that the garbage collector may erase at any time. - A weak pointer is said to be full if it points to an object, - empty if the object was erased by the GC. + A weak pointer is said to be full if it points to a value, + empty if the value was erased by the GC. *) val create : int -> 'a t;; (* [Weak.create n] returns a new weak array of length [n]. - All the pointers are initially empty. + All the pointers are initially empty. Raise [Invalid_argument] + if [n] is negative or greater than [Sys.max_array_length-1]. *) val length : 'a t -> int;; (* [Weak.length ar] returns the length (number of elements) of @@ -39,10 +40,23 @@ val set : 'a t -> int -> 'a option -> unit;; *) val get : 'a t -> int -> 'a option;; (* [Weak.get ar n] returns None if the [n]th cell of [ar] is - empty, [Some x] (where [x] is the object) if it is full. + empty, [Some x] (where [x] is the value) if it is full. Raise [Invalid_argument "Weak.get"] if [n] is not in the range 0 to [Weak.length a - 1]. *) + +val get_copy : 'a t -> int -> 'a option;; + (* [Weak.get_copy ar n] returns None if the [n]th cell of [ar] is + empty, [Some x] (where [x] is a (shallow) copy of the value) if + it is full. + In addition to pitfalls with mutable values, the interesting + difference with [get] is that [get_copy] does not prevent + the incremental GC from erasing the value in its current cycle + ([get] may delay the erasure to the next GC cycle). + Raise [Invalid_argument "Weak.get"] if [n] is not in the range + 0 to [Weak.length a - 1]. + *) + val check: 'a t -> int -> bool;; (* [Weak.check ar n] returns [true] if the [n]th cell of [ar] is full, [false] if it is empty. Note that even if [Weak.check ar n] |