commit 9e707626a85669db73e13acde179b079e6d81344
parent 60a7423b2d7414599b88177a5d6bcf7ce728f3d5
Author: Georges Dupéron <georges.duperon@gmail.com>
Date: Fri, 28 Apr 2017 23:28:48 +0200
Comments, fixed a few small bugs, bumped version number.
Diffstat:
4 files changed, 83 insertions(+), 11 deletions(-)
diff --git a/info.rkt b/info.rkt
@@ -14,5 +14,5 @@
"scribble-math"))
(define scribblings '(("scribblings/subtemplate.scrbl" () (parsing-library))))
(define pkg-desc "Various enhancements on syntax templates")
-(define version "1.0")
+(define version "1.1")
(define pkg-authors '("Georges Dupéron"))
diff --git a/private/top-subscripts.rkt b/private/top-subscripts.rkt
@@ -14,6 +14,12 @@
(define-syntax (top stx)
(define/with-syntax bound (stx-cdr stx))
+ ;; find-subscript-binders detects the xᵢ pattern variables declared outside of
+ ;; the #'bound syntax, for which a corresponding yᵢ occurs within the #'bound
+ ;; syntax. Since #'bound should normally be a single identifier, this will in
+ ;; effect check whether #'bound is of the form yᵢ, and if so whether a
+ ;; corresponding pattern variable xᵢ is within scope. The ᵢ can be any
+ ;; subscript, as long as it is the same for xᵢ and yᵢ.
(define binders+info (find-subscript-binders #'bound))
(if binders+info
@@ -38,4 +44,6 @@
((ellipsis-count/c ellipsis-depth) (list (attribute* binder) …))
;; actually call template or quasitemplate
bound)))
+ ;; If #'bound was not of the form yᵢ, or if we did not find a matching
+ ;; pattern variable xᵢ, we fall back to the original #%top implementation
(datum->syntax stx `(,#'#%top . ,#'bound))))
\ No newline at end of file
diff --git a/private/unsyntax-preparse.rkt b/private/unsyntax-preparse.rkt
@@ -38,32 +38,60 @@
(syntax-parse tmpl
#:literals (unsyntax unsyntax-splicing unquote unquote-splicing
quasitemplate ?? ?if ?cond ?attr ?@ ?@@)
- [({~and u unsyntax} (unquote e)) ;; full unquote with #,,
+ [({~and u unsyntax} (unquote e))
+ #:when (and (= escapes 0) quasi?)
+ ;; full unsyntax with #,,e
(ds `(,#'u ,#'e))]
- [({~and u unsyntax-splicing} (unquote e)) ;; full unquote with #,@,
+ [({~and u unsyntax-splicing} (unquote e))
+ #:when (and (= escapes 0) quasi?)
+ ;; full unsyntax-splicing with #,@,e
(ds `(,#'u ,#'e))]
- [({~and u unsyntax} (unquote-splicing e)) ;; full unquote with #,,@
+ [({~and u unsyntax} (unquote-splicing e))
+ #:when (and (= escapes 0) quasi?)
+ ;; full unsyntax-splicing with #,,@e
(ds `(,(datum->syntax #'here 'unsyntax-splicing #'u) ,#'e))]
[({~and u unsyntax} e)
#:when (and (= escapes 0) quasi?)
+ ;; ellipsis-preserving unsyntax with #,e
+ ;; If we are nested at depth D, this lifts a syntax pattern variable
+ ;; definition for (((tmp ...) ...) ...), with D levels of nesting.
+ ;; It uses "begin" from subtemplate/private/ddd-forms to generate the
+ ;; values for tmp succinctly. The template #'e is evaluated as many times
+ ;; as necessary by "begin", each time stepping the variables under
+ ;; ellipses.
(with-syntax ([tmp (generate-temporary #'e)]
[ooo* (map (λ (_) (quote-syntax …)) (range depth))])
+ ;; The value returned by e is wrapped in a list via (splice-append e).
+ ;; Normally, the list will contain a single element, unless e was a
+ ;; splicing list, in which case it may contain multiple elements.
(lift! #`(begin (define/with-syntax tmp (splice-append e)) . ooo*))
+ ;; Finally, tmp is inserted into the template (the current position is
+ ;; under D levels of ellipses) using (?@) to destroy the wrapper list.
+ ;; This allows #,(?@ 1 2 3) to be equivalent to #,@(list 1 2 3).
(ds `(,#'stxparse:?@ . ,(datum->syntax #'tmp #'tmp #'e))))]
[({~and u unsyntax-splicing} e)
+ ;; ellipsis-preserving unsyntax-splicing with #,@e
+ ;; This works in the same way as the #,e case just above…
#:when (and (= escapes 0) quasi?)
(with-syntax ([tmp (generate-temporary #'e)]
[ooo* (map (λ (_) (quote-syntax …)) (range depth))])
+ ;; … with the notable difference that splice-append* is used instead of
+ ;; splice-append.
(lift! #`(begin (define/with-syntax tmp (splice-append* e)) . ooo*))
- #'(stxparse:?@ . tmp))]
+ (ds `(,#'stxparse:?@ . ,(datum->syntax #'tmp #'tmp #'e))))]
[({~and u {~or unsyntax unsyntax-splicing}} e)
- ;; when escapes ≠ 0 (or quasi? is #false)
- (ds `(,#'u ,(pre-parse-unsyntax e depth (sub1 escapes) quasi? form)))]
+ ;; Undo one level of protection, so that in #`#`#,x the inner #` adds one
+ ;; level of escapement, and #, undoes that escapement.
+ ;; Normally, escapes > 0 here (or quasi? is #false)
+ (ds `(,#'u ,(pre-parse-unsyntax #'e depth (sub1 escapes) quasi? form)))]
[(quasitemplate t . opts)
+ ;; #`#`#,x does not unquote x, because it is nested within two levels of
+ ;; quasitemplate. We reproduce this behaviour here.
(ds `(,#'quasitemplate
,(pre-parse-unsyntax #'t depth (add1 escapes) quasi? form)
. ,#'opts))]
[({~and self ?if} condition a b)
+ ;; Special handling for the (?if condition a b) meta-operator
(with-syntax ([tmp (generate-temporary #'self)]
[ooo* (map (λ (_) (quote-syntax …)) (range depth))])
(lift! #`(begin (define/with-syntax tmp (?if #,(form (recur #'condition))
@@ -72,14 +100,19 @@
. ooo*))
#'(stxparse:?@ . tmp))]
[({~and self ?cond} [{~and condition {~not {~literal else}}} . v] . rest)
+ ;; Special handling for the ?cond meta-operator, when the first case has
+ ;; the shape [condition . v], but not [else . v]
(recur (ds `(,#'?if ,#'condition
,(ds `(,#'?@ . ,#'v))
,(ds `(,#'self . ,#'rest)))))]
[({~and self ?cond} [{~literal else}] . rest)
+ ;; ?cond meta-operator, when the first case has the shape [else]
#'(stxparse:?@)]
[({~and self ?cond} [{~literal else} . v] . rest)
+ ;; ?cond meta-operator, when the first case has the shape [else . v]
(recur #'(?@ . v))]
[({~and self ?@@} . e)
+ ;; Special handling for the special (?@@ . e) meta-operator
(with-syntax ([tmp (generate-temporary #'self)]
[ooo* (map (λ (_) (quote-syntax …)) (range depth))])
(lift! #`(begin (define/with-syntax tmp
@@ -87,23 +120,32 @@
. ooo*))
#'(stxparse:?@ . tmp))]
[({~and self ?attr} condition)
+ ;; Special handling for the special (?attr a) meta-operator
(recur (ds `(,#'?if ,#'condition
#t
#f)))]
[(:ooo t)
- tmpl] ;; fully escaped, do not change
+ ;; Ellipsis used to escape part of a template, i.e. (... escaped)
+ tmpl] ;; tmpl is fully escaped: do not change anything, pass the ... along
[({~and self ??} a b c . rest)
+ ;; Extended ?? from syntax/parse with three or more cases
(ds `(,#'stxparse:?? ,(recur #'a)
,(recur (ds `(,#'self ,#'b ,#'c . ,#'rest)))))]
[(?? a b)
+ ;; ?? from syntax/parse with two cases
(ds `(,#'stxparse:?? ,(recur #'a) ,(recur #'b)))]
[(?? a)
+ ;; ?? from syntax/parse with a single case (implicit (?@) as the else case)
(ds `(,#'stxparse:?? ,(recur #'a)))]
[(?@ . args)
+ ;; ?@ from syntax/parse
(ds `(,#'stxparse:?@ . ,(recur #'args)))]
[({~var mf (static template-metafunction? "template metafunction")} . args)
+ ;; template metafunction from stxparse-info/parse (incompatible with
+ ;; syntax/parse's metafunctions until PR racket/racket#1591 is merged).
(ds `(,#'mf . ,(recur #'args)))]
[(hd :ooo ...+ . tl)
+ ;; (hd ... . tl), with one or more ellipses after hd
(ds `(,(pre-parse-unsyntax #'hd
(+ depth (stx-length #'(ooo …)))
escapes
@@ -112,9 +154,11 @@
,@(syntax->list #'(ooo ...))
. ,(recur #'tl)))]
[(hd . tl)
+ ;; (hd . tl)
(ds `(,(recur #'hd) . ,(recur #'tl)))]
[#(t …)
- (ds (list->vector (stx-map recur #'(t …))))]
+ ;; #(t …)
+ (ds (vector->immutable-vector (list->vector (stx-map recur #'(t …)))))]
;; other ids, empty list, numbers, strings, chars, …
[_ tmpl]))
@@ -155,8 +199,8 @@
(define-syntax quasitemplate-ddd (*template-ddd #t #'quasitemplate))
(define-syntax quasisubtemplate-ddd (*template-ddd #t #'quasisubtemplate))
-(define-syntax template-ddd (*template-ddd #t #'template))
-(define-syntax subtemplate-ddd (*template-ddd #t #'subtemplate))
+(define-syntax template-ddd (*template-ddd #f #'template))
+(define-syntax subtemplate-ddd (*template-ddd #f #'subtemplate))
(define (stx-map*syntax->list e)
(let loop ([l (syntax->list e)])
diff --git a/test/test-unsyntax2.rkt b/test/test-unsyntax2.rkt
@@ -0,0 +1,20 @@
+#lang racket
+(require subtemplate/override
+ rackunit)
+
+(check-equal? (syntax->datum
+ (quasitemplate (a b #,(+ 1 1) c)))
+ '(a b 2 c))
+
+(check-equal? (syntax->datum
+ (template (a b #,(+ 1 1) c)))
+ (let ([u 'unsyntax])
+ `(a b (,u (+ 1 1)) c)))
+
+(check-equal? (syntax->datum
+ (quasitemplate (a b #,@(list (?@ 1 2) (?@ 3 4)) c)))
+ '(a b 1 2 3 4 c))
+
+(check-equal? (syntax->datum
+ #`(a b #,@(list (?@ 1 2) (?@ 3 4)) c))
+ '(a b 1 2 3 4 c))
