198 lines
7.7 KiB
Racket
198 lines
7.7 KiB
Racket
#lang scribble/doc
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@require["mz.ss"]
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@title[#:tag "stxops"]{Syntax Object Content}
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@defproc[(syntax? [v any/c]) boolean?]{
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Returns @scheme[#t] if @scheme[v] is a @tech{syntax object}, @scheme[#f]
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otherwise. See also @secref["stxobj-model"].}
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@defproc[(syntax-source [stx syntax?]) any]{
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Returns the source for the syntax object @scheme[stx], or @scheme[#f]
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if none is known. The source is represented by an arbitrary value
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(e.g., one passed to @scheme[read-syntax]), but it is typically a file
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path string. Source-location information is dropped for a syntax
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object that is marshaled as part of compiled code; see also
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@scheme[current-compile].}
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@defproc[(syntax-line [stx syntax?])
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(or/c positive-exact-integer?
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false/c)]{
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Returns the line number (positive exact integer) for the start of the
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syntax object in its source, or @scheme[#f] if the line number or
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source is unknown. The result is @scheme[#f] if and only if
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@scheme[(syntax-column stx)] produces @scheme[#f]. See also
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@secref["linecol"], and see @scheme[syntax-source] for information
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about marshaling compiled syntax objects.}
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@defproc[(syntax-column [stx syntax?])
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(or/c nonnegative-exact-integer?
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false/c)]{
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Returns the column number (non-negative exact integer) for the start
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of the syntax object in its source, or @scheme[#f] if the source
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column is unknown. The result is @scheme[#f] if and only if
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@scheme[(syntax-line stx)] produces @scheme[#f]. See also
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@secref["linecol"], and see @scheme[syntax-source] for information
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about marshaling compiled syntax objects.}
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@defproc[(syntax-position [stx syntax?])
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(or/c positive-exact-integer?
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false/c)]{
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Returns the character position (positive exact integer) for the start
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of the syntax object in its source, or @scheme[#f] if the source
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position is unknown. See also @secref["linecol"], and see
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@scheme[syntax-source] for information about marshaling compiled
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syntax objects.}
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@defproc[(syntax-span [stx syntax?])
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(or/c nonnegative-exact-integer?
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false/c)]{
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Returns the span (non-negative exact integer) in characters of the
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syntax object in its source, or @scheme[#f] if the span is
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unknown. See also @scheme[syntax-source] for information about
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marshaling compiled syntax objects.}
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@defproc[(syntax-original? [stx syntax?]) boolean?]{
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Returns @scheme[#t] if @scheme[stx] has the property that
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@scheme[read-syntax] and @scheme[read-honu-syntax] attach to the
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syntax objects that they generate (see @secref["stxprops"]), and if
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@scheme[stx]'s @tech{lexical information} does not indicate that the
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object was introduced by a syntax transformer (see
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@secref["stxobj-model"]). The result is @scheme[#f] otherwise. This
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predicate can be used to distinguish syntax objects in an expanded
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expression that were directly present in the original expression, as
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opposed to syntax objects inserted by macros.}
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@defproc[(syntax-source-module [stx syntax?])
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(or/c module-path-index? symbol?)]{
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Returns a module path index or symbol (see @secref["modpathidx"])
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for the module whose source contains @scheme[stx], or @scheme[#f] if
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@scheme[stx] has no source module.}
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@defproc[(syntax-e [stx syntax?]) any]{
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Unwraps the immediate datum structure from a syntax object,
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leaving nested syntax structure (if any) in place. The result of
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@scheme[(syntax-e @scheme[stx])] is one of the following:
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@itemize{
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@item{a symbol}
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@item{a @tech{syntax pair} (described below)}
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@item{the empty list}
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@item{a vector containing syntax objects}
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@item{some other kind of datum---usually a number, boolean, or string}
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}
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A @deftech{syntax pair} is a pair containing a syntax object as its
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first element, and either the empty list, a syntax pair, or a syntax
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object as its second element.
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A syntax object that is the result of @scheme[read-syntax] reflects
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the use of delimited @litchar{.} in the input by creating a syntax
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object for every pair of parentheses in the source, and by creating a
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pair-valued syntax object @italic{only} for parentheses in the
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source. See @secref["parse-pair"] for more information.}
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@defproc[(syntax->list [stx syntax?])
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(or/c list? false/c)]{
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Returns an immutable list of syntax objects or @scheme[#f]. The result
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is a list of syntax objects when @scheme[(syntax->datum stx)]
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would produce a list. In other words, @tech{syntax pairs} in
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@scheme[(syntax-e @scheme[stx])] are flattened.}
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@defproc[(syntax->datum ...) any]{
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Returns a datum by stripping the lexical and source-location
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information from @scheme[stx]. Graph structure is preserved by the
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conversion.}
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@defproc[(datum->syntax [ctxt (or/c syntax? false/c)]
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[v any/c]
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[srcloc (or/c syntax? false/c
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(list/c any/c
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(or/c positive-exact-integer? false/c)
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(or/c nonnegative-exact-integer? false/c)
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(or/c nonnegative-exact-integer? false/c)
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(or/c positive-exact-integer? false/c)))]
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[prop (or/c syntax? false/c) #f]
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[cert (or/c syntax? false/c) #f])
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syntax?]{
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Converts the @tech{datum} @scheme[v] to a @tech{syntax object}, using
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syntax objects already in @scheme[v] in the result. Converted objects
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in @scheme[v] are given the lexical context information of
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@scheme[ctxt] and the source-location information of
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@scheme[srcloc]. If @scheme[v] is not already a syntax object, then
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the resulting immediate syntax object it is given the properties (see
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@secref["stxprops"]) of @scheme[prop] and the @tech{inactive certificates}
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(see @secref["stxcerts"]) of @scheme[cert]. Any of
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@scheme[ctxt], @scheme[srcloc], @scheme[prop], or @scheme[cert] can be
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@scheme[#f], in which case the resulting syntax has no lexical
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context, source information, new properties, and/or certificates.
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If @scheme[srcloc] is not @scheme[#f]
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or a syntax object, it must be a list of five elements:
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@schemeblock[
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(list source-name line column position span)
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]
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where @scheme[source-name-v] is an arbitrary value for the source
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name; @scheme[line] is an integer for the source line, or @scheme[#f];
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@scheme[column] is an integer for the source column, or @scheme[#f];
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@scheme[position] is an integer for the source position, or
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@scheme[#f]; and @scheme[span] is an integer for the source span, or
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@scheme[#f]. The @scheme[line] and @scheme[column] values must both be
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numbers or both be @scheme[#f], otherwise the
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@exnraise[exn:fail:contract].
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Graph structure is preserved by the conversion of @scheme[v] to a
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syntax object, but graph structure that is distributed among distinct
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syntax objects in @scheme[v] may be hidden from future applications of
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@scheme[syntax->datum] and @scheme[syntax-graph?] to the new
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syntax object.}
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@defproc[(identifier? [v any/c]) boolean?]{
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Returns @scheme[#t] if @scheme[v] is a syntax object and
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@scheme[(syntax-e stx)] produces a symbol.}
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@defproc[(generate-temporaries [stx-pair (or syntax? list?)])
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(listof identifier?)]{
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Returns a list of identifiers that are distinct from all other
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identifiers. The list contains as many identifiers as
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@scheme[stx-pair] contains elements. The @scheme[stx-pair] argument
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must be a syntax pair that can be flattened into a list. The elements
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of @scheme[stx-pair] can be anything, but string, symbol, keyword
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(possibly wrapped as syntax), and identifier elements will be embedded
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in the corresponding generated name, which is useful for debugging
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purposes. The generated identifiers are built with interned symbols
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(not @scheme[gensym]s), so the limitations described with
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@scheme[current-compile] do not apply.}
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