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Metafunctions now respect caching-enabled? and set-cache-size!.

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svn: r17271
This commit is contained in:
Casey Klein 2009-12-11 20:54:32 +00:00
parent 0c03246daa
commit 4f140eed03
3 changed files with 24 additions and 24 deletions
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1
collects/redex/private/matcher.ss
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@ -1592,6 +1592,7 @@ before the pattern compiler is invoked.
compiled-pattern?))
(set-cache-size! (-> (and/c integer? positive?) void?))
(cache-size (and/c integer? positive?))
(make-bindings ((listof bind?) . -> . bindings?))
(bindings-table (bindings? . -> . (listof bind?)))

14
collects/redex/private/reduction-semantics.ss
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@ -1425,7 +1425,15 @@
(values
(wrap
(letrec ([cache (make-hash)]
[cache-entries 0]
[not-in-cache (gensym)]
[cache-result (λ (arg res case)
(when (caching-enabled?)
(when (>= cache-entries cache-size)
(set! cache (make-hash))
(set! cache-entries 0))
(hash-set! cache arg (cons res case))
(set! cache-entries (add1 cache-entries))))]
[log-coverage (λ (id)
(when id
(for-each
@ -1452,7 +1460,7 @@
[(null? cases)
(if relation?
(begin
(hash-set! cache exp (cons #f #f))
(cache-result exp #f #f)
#f)
(redex-error name "no clauses matched for ~s" `(,name . ,exp)))]
[else
@ -1470,7 +1478,7 @@
(redex-error name "codomain test failed for ~s, call was ~s" ans `(,name ,@exp)))
(cond
[ans
(hash-set! cache exp (cons #t id))
(cache-result exp #t id)
(log-coverage id)
#t]
[else
@ -1499,7 +1507,7 @@
"codomain test failed for ~s, call was ~s"
ans
`(,name ,@exp)))
(hash-set! cache exp (cons ans id))
(cache-result exp ans id)
(log-coverage id)
ans)]))])))]))]
[else

33
collects/redex/redex.scrbl
View File

@ -369,28 +369,19 @@ clause is followed by an ellipsis. Nested ellipses produce
nested lists.
}
@defproc[(set-cache-size! [size positive-integer?]) void?]{
Changes the cache size; the default size is @scheme[350].
The cache is per-pattern (ie, each pattern has a cache of size at most
350 (by default)) and is a simple table that maps expressions to how
they matched the pattern (ie, the bindings for the pattern
variables). When the cache gets full, it is thrown away and a new
cache is started.
@defparam[caching-enabled? on? boolean?]{
When this parameter is @scheme[#t] (the default), Redex caches the results of
pattern matching and metafunction evaluation. There is a separate cache for
each pattern and metafunction; when one fills (see @scheme[set-cache-size!]),
Redex evicts all of the entries in that cache.
Caching should be disabled when matching a pattern that depends on values
other than the in-scope pattern variables or evaluating a metafunction
that reads or writes mutable external state.
}
@defparam[caching-enabled? on? boolean?]{
This is a parameter that controls whether or not a cache
is consulted (and updated) while matching and while evaluating
metafunctions.
If it is @scheme[#t], then side-conditions and the right-hand sides
of metafunctions are assumed to only depend on the values of the
pattern variables in scope (and thus not on any other external
state).
Defaults to @scheme[#t].
@defproc[(set-cache-size! [size positive-integer?]) void?]{
Changes the size of the per-pattern and per-metafunction caches. The default size is @scheme[350].
}
@section{Terms}
@ -921,7 +912,7 @@ or if the contract is violated.
Note that metafunctions are assumed to always return the same results
for the same inputs, and their results are cached, unless
@scheme[caching-enable?] is set to @scheme[#f]. Accordingly, if a
@scheme[caching-enabled?] is set to @scheme[#f]. Accordingly, if a
metafunction is called with the same inputs twice, then its body is
only evaluated a single time.