218 lines
7.9 KiB
Racket
218 lines
7.9 KiB
Racket
#lang scribble/doc
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@(require "mz.ss")
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@(define stx-eval (make-base-eval))
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@(interaction-eval #:eval stx-eval (require (for-syntax racket/base)))
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@title[#:tag "stxcmp"]{Syntax Object Bindings}
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@defproc[(bound-identifier=? [a-id syntax?] [b-id syntax?]
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[phase-level (or/c exact-integer? #f)
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(syntax-local-phase-level)])
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boolean?]{
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Returns @scheme[#t] if the identifier @scheme[a-id] would bind
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@scheme[b-id] (or vice versa) if the identifiers were substituted in a
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suitable expression context at the @tech{phase level} indicated by
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@scheme[phase-level], @scheme[#f] otherwise. A @scheme[#f] value for
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@scheme[phase-level] corresponds to the @tech{label phase level}.
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@examples[
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#:eval stx-eval
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(define-syntax (check stx)
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(syntax-case stx ()
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[(_ x y)
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(if (bound-identifier=? #'x #'y)
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#'(let ([y 'wrong]) (let ([x 'binds]) y))
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#'(let ([y 'no-binds]) (let ([x 'wrong]) y)))]))
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(check a a)
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(check a b)
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(define-syntax-rule (check-a x) (check a x))
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(check-a a)
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]}
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@defproc[(free-identifier=? [a-id syntax?] [b-id syntax?]
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[phase-level (or/c exact-integer? #f)
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(syntax-local-phase-level)])
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boolean?]{
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Returns @scheme[#t] if @scheme[a-id] and @scheme[b-id] access the same
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@tech{local binding}, @tech{module binding}, or @tech{top-level
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binding}---perhaps via @tech{rename transformers}---at the @tech{phase
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level} indicated by @scheme[phase-level]. A @scheme[#f] value for
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@scheme[phase-level] corresponds to the @tech{label phase level}.
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``Same module binding'' means that the identifiers refer to the same
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original definition site, and not necessarily to the same
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@scheme[require] or @scheme[provide] site. Due to renaming in
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@scheme[require] and @scheme[provide], or due to a transformer binding
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to a @tech{rename transformer}, the identifiers may return distinct
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results with @scheme[syntax-e].
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@examples[
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#:eval stx-eval
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(define-syntax (check stx)
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(syntax-case stx ()
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[(_ x)
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(if (free-identifier=? #'car #'x)
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#'(list 'same: x)
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#'(list 'different: x))]))
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(check car)
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(check mcar)
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(let ([car list])
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(check car))
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(require (rename-in racket/base [car kar]))
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(check kar)
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]}
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@defproc[(free-transformer-identifier=? [a-id syntax?] [b-id syntax?]) boolean?]{
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Same as @scheme[(free-identifier=? a-id b-id (add1 (syntax-local-phase-level)))].}
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@defproc[(free-template-identifier=? [a-id syntax?] [b-id syntax?]) boolean?]{
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Same as @scheme[(free-identifier=? a-id b-id (sub1 (syntax-local-phase-level)))].}
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@defproc[(free-label-identifier=? [a-id syntax?] [b-id syntax?]) boolean?]{
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Same as @scheme[(free-identifier=? a-id b-id #f)].}
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@defproc[(check-duplicate-identifier [ids (listof identifier?)])
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(or/c identifier? #f)]{
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Compares each identifier in @scheme[ids] with every other identifier
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in the list with @scheme[bound-identifier=?]. If any comparison
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returns @scheme[#t], one of the duplicate identifiers is returned (the
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first one in @scheme[ids] that is a duplicate), otherwise the result
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is @scheme[#f].}
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@defproc[(identifier-binding [id-stx syntax?]
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[phase-level (or/c exact-integer? #f)
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(syntax-local-phase-level)])
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(or/c 'lexical
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#f
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(listof module-path-index?
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symbol?
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module-path-index?
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symbol?
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(or/c 0 1)
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(or/c exact-integer? #f)
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(or/c exact-integer? #f)))]{
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Returns one of three kinds of values, depending on the binding of
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@scheme[id-stx] at the @tech{phase level} indicated by
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@scheme[phase-level] (where a @scheme[#f] value for
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@scheme[phase-level] corresponds to the @tech{label phase level}):
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@itemize[
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@item{The result is @indexed-scheme['lexical] if @scheme[id-stx]
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has a @tech{local binding}. If @scheme['lexical] is produced for
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any @scheme[phase-level] value, then it is produced for all
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@scheme[phase-level] values.}
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@item{The result is a list of seven items when @scheme[id-stx]
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has a @tech{module binding}: @scheme[(list _source-mod _source-id
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_nominal-source-mod _nominal-source-id _source-phase _import-phase
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_nominal-export-phase)].
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@itemize[
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@item{@scheme[_source-mod] is a module path index (see
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@secref["modpathidx"]) that indicates the defining module.}
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@item{@scheme[_source-id] is a symbol for the identifier's name
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at its definition site in the source module. This can be
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different from the local name returned by
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@scheme[syntax->datum] for several reasons: the identifier is
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renamed on import, it is renamed on export, or it is
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implicitly renamed because the identifier (or its import) was
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generated by a macro invocation.}
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@item{@scheme[_nominal-source-mod] is a module path index (see
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@secref["modpathidx"]) that indicates the module
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@scheme[require]d into the context of @scheme[id-stx] to
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provide its binding. It can be different from
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@scheme[_source-mod] due to a re-export in
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@scheme[_nominal-source-mod] of some imported identifier. If
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the same binding is imported in multiple ways, an arbitrary
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representative is chosen.}
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@item{@scheme[_nominal-source-id] is a symbol for the
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identifier's name as exported by
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@scheme[_nominal-source-mod]. It can be different from
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@scheme[_source-id] due to a renaming @scheme[provide], even if
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@scheme[_source-mod] and @scheme[_nominal-source-mod] are the
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same.}
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@item{@scheme[_source-phase] is @scheme[1] if the source
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definition is for-syntax, @scheme[0] otherwise.}
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@item{@scheme[_import-phase] is @scheme[0] if the binding
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import of @scheme[_nominal-source-mode] is a plain
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@scheme[require], @scheme[1] if it is from a
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@scheme[for-syntax] import, etc.}
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@item{@scheme[_nominal-export-phase] is the @tech{phase level}
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of the export from @scheme[_nominal-source-mod].}
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]}
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@item{The result is @scheme[#f] if @scheme[id-stx] has a
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@tech{top-level binding} (or, equivalently, if it is
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@tech{unbound}).}
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]
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If @scheme[id-stx] is bound to a @tech{rename-transformer}, the result
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from @scheme[identifier-binding] is for the identifier in the
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transformer, so that @scheme[identifier-binding] is consistent with
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@scheme[free-identifier=?].}
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@defproc[(identifier-transformer-binding [id-stx syntax?])
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(or/c 'lexical
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#f
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(listof module-path-index?
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symbol?
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module-path-index?
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symbol?
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(or/c 0 1)
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(or/c exact-integer? #f)
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(or/c exact-integer? #f)))]{
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Same as @scheme[(identifier-binding id-stx (add1 (syntax-local-phase-level)))].}
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@defproc[(identifier-template-binding [id-stx syntax?])
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(or/c 'lexical
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#f
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(listof module-path-index?
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symbol?
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module-path-index?
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symbol?
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(or/c 0 1)
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(or/c exact-integer? #f)
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(or/c exact-integer? #f)))]{
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Same as @scheme[(identifier-binding id-stx (sub1 (syntax-local-phase-level)))].}
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@defproc[(identifier-label-binding [id-stx syntax?])
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(or/c 'lexical
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#f
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(listof module-path-index?
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symbol?
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module-path-index?
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symbol?
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(or/c 0 1)
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(or/c exact-integer? #f)
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(or/c exact-integer? #f)))]{
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Same as @scheme[(identifier-binding id-stx #f)].}
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@close-eval[stx-eval]
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