34 meta operations on structs

34

meta operations on structs

7.7

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34 meta operations on structs

Georges Dupéron <georges.duperon@gmail.com>

34.1 Typed macros and procedures

(require phc-toolkit/meta-struct)

package: phc-toolkit

syntax
(struct-predicate s)

s = meta-struct?

Expands to a predicate for the given struct, with the type (-> any/c boolean? : s).

syntax
(struct-constructor s)

s = meta-struct?

This macro expands to the constructor function for the given struct, with the type (-> arg … s) where each arg corresponds to an argument expected by the struct’s constructor.

syntax
(struct-accessor s i)
(struct-accessor s field)

s = meta-struct?

i = (expr/c exact-nonnegative-integer?)

field = identifier?

This macro expands to the i-th accessor function for the given struct, with the type (-> s t) where t is the struct’s i-th field’s type.

If the second argument is an identifier, then this macro concatenates the identifiers s and field with a - in between, and expands to the resulting s-field. The lexical context of s-field is the same as the lexical context of s. In some rare cases this might not resolve to the accessor for field on s. Passing an exact-nonnegative-integer? as the second argument should be more reliable.

phase 1 procedure
(struct-type-is-immutable? st) → boolean?
st : Struct-TypeTop

Returns #t if the given struct type can be determined to have only immutable fields. Returns #f otherwise.

procedure
(struct-instance-is-immutable? v) → boolean?
v : struct?

Returns #t if v can be determined to be an instance of an immutable struct. Returns #f otherwise. Note that when given an instance of an opaque struct struct-instance-is-immutable? cannot access the struct info, and therefore returns #f.

34.2 Untyped versions of the meta-struct typed macros

(require phc-toolkit/untyped/meta-struct)
	package: phc-toolkit

syntax
struct-predicate

Untyped version of struct-predicate.

syntax
struct-constructor

Untyped version of struct-constructor.

syntax
struct-accessor

Untyped version of struct-accessor.

syntax
struct-type-is-immutable?

Untyped version of struct-type-is-immutable?.

syntax
struct-instance-is-immutable?

Untyped version of struct-instance-is-immutable?.

34.3 Untyped for-syntax utilities

(require phc-toolkit/untyped/meta-struct)
	package: phc-toolkit

procedure
(meta-struct? v) → boolean?
v : any/c

Returns #t if v can be used by the functions provided by this module, and #f otherwise. More precisely, v must be an identifier whose syntax-local-value is a struct-info?.

Changed in version 1.0 of package phc-toolkit: This function is provided at phase 1.

struct
(struct meta-struct-info ( type-descriptor
constructor
predicate
accessors
mutators
super-type)
    #:extra-constructor-name make-meta-struct-info)
  type-descriptor : (or/c identifier? #f)
  constructor : (or/c identifier? #f)
  predicate : (or/c identifier? #f)
   accessors :
(list*of identifier?
         (or/c (list/c #f) null?))
   mutators :
(list*of (or/c identifier? #f)
         (or/c (list/c #f) null?))
  super-type : (or/c identifier? #f)

Encapsulates the result of extract-struct-info in a structure with named fields, instead of an obscure six-element list. The precise contents of each field is described in Structure Type Transformer Binding.

Changed in version 1.0 of package phc-toolkit: The identifiers are provided at phase 1.

procedure
(get-meta-struct-info s [#:srcloc srcloc]) → meta-struct-info?
s : meta-struct?
srcloc : (or/c #f syntax?) = #f

Returns the meta-struct-info for the given identifier. The optional #:srcloc keyword argument gives the source location for error messages in case the given identifier is not a meta-struct?.

Changed in version 1.0 of package phc-toolkit: This function is provided at phase 1.

procedure
(meta-struct-subtype? sub super) → boolean?
sub : meta-struct?
super : meta-struct?

Returns #t if the struct associated to the identifier sub is a subtype of the struct associated to the identifier super, and #f otherwise or if the current inspector is not strong enough to know.

Changed in version 1.0 of package phc-toolkit: This function is provided at phase 1.

phase 1 procedure
(struct-type-id-is-immutable? id) → boolean?
id : identifier?

Returns #t if the struct with the given id can be determined to have only immutable fields. Returns #f otherwise.

procedure
(meta-struct-type-descriptor s
[ #:srcloc srcloc])
→
(expressionof
(→ s (or/c identifier? #f)))
s : meta-struct?
srcloc : (or/c #f syntax?) = #f
template metafunction
(!struct-type-descriptor s maybe-srcloc)

s = meta-struct?

maybe-srcloc =
| #:srcloc srcloc

Shorthand for (meta-struct-info-type-descriptor (get-meta-struct-info s)) (with the optional #:srcloc passed to get-meta-struct-info). The precise contents of the returned value field is described in Structure Type Transformer Binding.

Changed in version 1.0 of package phc-toolkit: This function is provided at phase 1.

procedure
(meta-struct-constructor s [#:srcloc srcloc])
→
(expressionof
(→ s (or/c identifier? #f)))
s : meta-struct?
srcloc : (or/c #f syntax?) = #f
template metafunction
(!struct-constructor s maybe-srcloc)

s = meta-struct?

maybe-srcloc =
| #:srcloc srcloc

Shorthand for (meta-struct-info-constructor (get-meta-struct-info s)) (with the optional #:srcloc passed to get-meta-struct-info). The precise contents of the returned value field is described in Structure Type Transformer Binding.

Changed in version 1.0 of package phc-toolkit: This function is provided at phase 1.

procedure
(meta-struct-predicate s [#:srcloc srcloc])
→
(expressionof
(→ s (or/c identifier? #f)))
s : meta-struct?
srcloc : (or/c #f syntax?) = #f
template metafunction
(!struct-predicate s maybe-srcloc)

s = meta-struct?

maybe-srcloc =
| #:srcloc srcloc

Shorthand for (meta-struct-info-predicate (get-meta-struct-info s)) (with the optional #:srcloc passed to get-meta-struct-info). The precise contents of the returned value field is described in Structure Type Transformer Binding.

Changed in version 1.0 of package phc-toolkit: This function is provided at phase 1.

procedure
(meta-struct-accessors s [#:srcloc srcloc])
→
(expressionof
(→ s (list*of identifier? (or/c (list/c #f) null?))))
s : meta-struct?
srcloc : (or/c #f syntax?) = #f
template metafunction
(!struct-accessors s maybe-srcloc)

s = meta-struct?

maybe-srcloc =
| #:srcloc srcloc

Shorthand for (meta-struct-info-accessors (get-meta-struct-info s)) (with the optional #:srcloc passed to get-meta-struct-info). The precise contents of the returned value field is described in Structure Type Transformer Binding.

Changed in version 1.0 of package phc-toolkit: This function is provided at phase 1.

procedure
(meta-struct-mutators s [#:srcloc srcloc])
→
(expressionof
(→ s (list*of (or/c identifier? #f) (or/c (list/c #f) null?))))
s : meta-struct?
srcloc : (or/c #f syntax?) = #f
template metafunction
(!struct-mutators s maybe-srcloc)

s = meta-struct?

maybe-srcloc =
| #:srcloc srcloc

Shorthand for (meta-struct-info-mutators (get-meta-struct-info s)) (with the optional #:srcloc passed to get-meta-struct-info). The precise contents of the returned value field is described in Structure Type Transformer Binding.

Changed in version 1.0 of package phc-toolkit: This function is provided at phase 1.

procedure
(meta-struct-super-type s [#:srcloc srcloc])
→
(expressionof
(→ s (or/c identifier? #f)))
s : meta-struct?
srcloc : (or/c #f syntax?) = #f
template metafunction
(!struct-super-type s maybe-srcloc)

s = meta-struct?

maybe-srcloc =
| #:srcloc srcloc

Shorthand for (meta-struct-info-super-type (get-meta-struct-info s)) (with the optional #:srcloc passed to get-meta-struct-info). The precise contents of the returned value field is described in Structure Type Transformer Binding.

Changed in version 1.0 of package phc-toolkit: This function is provided at phase 1.

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