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add prop:struct-info

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svn: r18730
This commit is contained in:
Matthew Flatt 2010-04-03 13:08:39 +00:00
parent 6cd548b0f3
commit 3cc95b31ef
3 changed files with 86 additions and 23 deletions
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48
collects/scheme/private/struct-info.ss
View File

@ -8,7 +8,18 @@
(#%provide make-struct-info
struct-info?
extract-struct-info
struct:struct-info)
struct:struct-info
prop:struct-info)
(define-values (prop:struct-info has-struct-info-prop? struct-info-prop-ref)
(make-struct-type-property 'struct-info
(lambda (v type-info)
(if (and (procedure? v)
(procedure-arity-includes? v 1))
v
(raise-type-error 'guard-for-prop:struct-info
"procedure (arity 1)"
v)))))
(define-values (struct:struct-info make-struct-info struct-info-rec?
struct-info-ref struct-info-set!)
@ -31,21 +42,34 @@
(define-values (extract-struct-info)
(lambda (si)
(if (struct-info-rec? si)
(let ([p (struct-info-ref si 0)])
(let ([v (p)])
(if (struct-declaration-info? v)
v
(error 'extract-struct-info
"struct-info procedure result not properly formed: ~e"
v))))
(if (set!-transformer? si)
(extract-struct-info (set!-transformer-procedure si))
si))))
(cond
[(struct-info-rec? si)
(let ([p (struct-info-ref si 0)])
(let ([v (p)])
(if (struct-declaration-info? v)
v
(error 'extract-struct-info
"struct-info procedure result not properly formed: ~e"
v))))]
[(has-struct-info-prop? si)
(let ([v ((struct-info-prop-ref si) si)])
(if (struct-declaration-info? v)
v
(error 'extract-struct-info
"prop:struct-info procedure result not properly formed: ~e"
v)))]
[(set!-transformer? si)
(extract-struct-info (set!-transformer-procedure si))]
[(struct-declaration-info? si) si]
[else (raise-type-error 'extract-struct-info
"struct-info"
si)])))
(define-values (struct-info?)
(lambda (si)
(or (struct-info-rec? si)
(and (has-struct-info-prop? si)
(not (struct-type? si)))
(struct-declaration-info? si)
(and (set!-transformer? si)
(struct-info-rec? (set!-transformer-procedure si))))))

33
collects/scribblings/reference/struct.scrbl
View File

@ -318,7 +318,7 @@ Creates a new structure type property and returns three values:
If the optional @scheme[guard] is supplied as a procedure, it is
called by @scheme[make-struct-type] before attaching the property to a
new structure type. The @scheme[guard-proc] must accept two arguments:
new structure type. The @scheme[guard] must accept two arguments:
a value for the property supplied to @scheme[make-struct-type], and a
list containing information about the new structure type. The list
contains the values that @scheme[struct-type-info] would return for
@ -596,14 +596,17 @@ encapsulated procedure must return):
]
Instead of this direct representation, the representation can
be a structure created by @scheme[make-struct-info] (or an instance of
a subtype of @scheme[struct:struct-info]), which encapsulates a
Instead of this direct representation, the representation can be a
structure created by @scheme[make-struct-info] (or an instance of a
subtype of @scheme[struct:struct-info]), which encapsulates a
procedure that takes no arguments and returns a list of six
elements. Finally, the representation can be an instance of a
structure type derived from @scheme[struct:struct-info] that also
implements @scheme[prop:procedure], and where the instance is further
is wrapped by @scheme[make-set!-transformer].
elements. Alternately, the representation can be a structure whose
type has the @scheme[prop:struct-info] @tech{structure type property}.
Finally, the representation can be an instance of a structure type
derived from @scheme[struct:struct-info] or with the
@scheme[prop:struct-info] property that also implements
@scheme[prop:procedure], and where the instance is further is wrapped
by @scheme[make-set!-transformer].
Use @scheme[struct-info?] to recognize all allowed forms of the
information, and use @scheme[extract-struct-info] to obtain a list
@ -626,9 +629,10 @@ type.
Returns @scheme[#t] if @scheme[v] is either a six-element list with
the correct shape for representing structure-type information, a
procedure encapsulated by @scheme[make-struct-info], or a structure
type derived from @scheme[struct:struct-info] and wrapped with
@scheme[make-set!-transformer].}
procedure encapsulated by @scheme[make-struct-info], a structure with
the @scheme[prop:struct-info] property, or a structure type derived
from @scheme[struct:struct-info] or with @scheme[prop:struct-info] and
wrapped with @scheme[make-set!-transformer].}
@defproc[(checked-struct-info? [v any/c]) boolean?]{
@ -657,6 +661,13 @@ mostly useful for creating structure subtypes. The structure type
includes a guard that checks an instance's first field in the same way
as @scheme[make-struct-info].}
@defthing[prop:struct-info struct-type-property?]{
The @tech{structure type property} for creating new structure types
like @scheme[struct:struct-info]. The property value must a procedure
of one argument that takes an instance structure and returns
structure-type information in list form.}
@; ----------------------------------------------------------------------
@close-eval[struct-eval]

28
collects/tests/mzscheme/struct.ss
View File

@ -977,4 +977,32 @@
;; ----------------------------------------
(require (for-syntax scheme/struct-info))
(let ()
(define-struct a (x y))
(define-syntax foo (make-struct-info
(lambda ()
(list #'struct:a #'make-a #'a?
(list #'a-y #'a-x)
(list #f #f)
#f))))
(define-syntax foo2 (let ()
(define-struct si (pred)
#:property
prop:struct-info
(lambda (v)
(list #'struct:a #'make-a (si-pred v)
(list #'a-y #'a-x)
(list #f #f)
#f)))
(make-si #'a?)))
(test (list 1 2) 'match (match (make-a 1 2)
[(struct foo (x y)) (list x y)]))
(test (list 1 2) 'match (match (make-a 1 2)
[(struct foo2 (x y)) (list x y)])))
;; ----------------------------------------
(report-errs)