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add splicing for right-hand ids

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This commit is contained in:
Matthew Butterick 2016-05-10 12:25:17 -07:00
parent 7c21df6ed4
commit f57653c43d
7 changed files with 26 additions and 19 deletions
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8
brag/brag/codegen/codegen.rkt
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@ -199,7 +199,7 @@
(for/list ([translated-pattern (in-list translated-patterns)]
[primitive-pattern (syntax->list a-clause)]
[pos (in-naturals 1)])
(if (syntax-property primitive-pattern 'hide)
(if (eq? (syntax-property primitive-pattern 'hide) 'hide)
#'null
(with-syntax ([$X
(format-id translated-pattern "$~a" pos)]
@ -217,7 +217,7 @@
[(inferred-rule-name . rest)
(syntax->list #'rest)])]
[(id val)
#'(list $X)]
#`(list (syntax-property $X 'splice-rh-id #,(and (syntax-property primitive-pattern 'hide) #t)))] ; at this point, this syntax-property is either #f or "splice"
[(lit val)
#'(list (atomic-datum->syntax $X $X-start-pos $X-end-pos))]
[(token val)
@ -230,13 +230,13 @@
[$n-end-pos (format-id (last translated-patterns) "$~a-end-pos" (length translated-patterns))])
#`(positions->srcloc $1-start-pos $n-end-pos))))
;; move 'hide-or-splice property into function because name is datum-ized
;; move 'hide-or-splice-lhs-id property into function because name is datum-ized
(with-syntax ([(translated-pattern ...) translated-patterns]
[(translated-action ...) translated-actions])
#`[(translated-pattern ...)
(rule-components->syntax '#,rule-name/false translated-action ...
#:srcloc #,whole-rule-loc
#:hide-or-splice? #,(syntax-property rule-name/false 'hide-or-splice))]))
#:hide-or-splice? #,(syntax-property rule-name/false 'hide-or-splice-lhs-id))]))

7
brag/brag/codegen/runtime.rkt
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@ -164,11 +164,12 @@ This would be the place to check a syntax property for hiding.
(define (rule-components->syntax rule-name/false #:srcloc [srcloc #f] #:hide-or-splice? [hide-or-splice #f] . componentss)
(let ([spliced-componentss (append-map (λ(cs)
(cond
[(and (pair? cs) (equal? (syntax-property (car cs) 'hide-or-splice) "hide"))
[(and (pair? cs) (eq? (syntax-property (car cs) 'hide-or-splice) 'hide))
(list (list (syntax-case (car cs) ()
[(rule-name c ...)
#'(c ...)])))]
[(and (pair? cs) (equal? (syntax-property (car cs) 'hide-or-splice) "splice"))
[(and (pair? cs) (or (eq? (syntax-property (car cs) 'hide-or-splice) 'splice)
(syntax-property (car cs) 'splice-rh-id)))
(list (cdr (syntax->list (car cs))))]
[else (list cs)])) componentss)])
(syntax-property
@ -178,4 +179,4 @@ This would be the place to check a syntax property for hiding.
(apply append spliced-componentss))
srcloc
stx-with-original?-property)
'hide-or-splice hide-or-splice)))
'hide-or-splice hide-or-splice))) ; not 'hide-or-splice-lhs-id, because it is now a component in a different rule

2
brag/brag/examples/baby-json-hider.rkt
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@ -3,7 +3,7 @@
;; Simple baby example of JSON structure
json: number | string
| array
| object
| @object
number: NUMBER

19
brag/brag/rules/parser.rkt
View File

@ -102,7 +102,7 @@
(position-line $1-start-pos)
(position-col $1-start-pos))
trimmed
"hide") ; symbols won't work for these signals
''hide) ; symbols won't work for these signals
$2))]
;; atsign indicates splicing. set hide value to "splice"
@ -117,7 +117,7 @@
(position-line $1-start-pos)
(position-col $1-start-pos))
trimmed
"splice")
''splice)
$2))]]
[pattern
@ -186,14 +186,23 @@
(relocate-pattern $2 (position->pos $1-start-pos) (position->pos $3-end-pos))]
[(BANG atomic-pattern)
;; bang indicates hiding. set hide value to #t
(relocate-pattern $2 (position->pos $1-start-pos) (position->pos $2-end-pos) #t)]])
;; bang indicates hiding. set hide value to hide
(relocate-pattern $2 (position->pos $1-start-pos) (position->pos $2-end-pos) 'hide)]
[(ATSIGN ID)
;; atsign indicates splicing. set hide value to splice
;; only works for nonterminals on the right side (meaningless with terminals)
(if (token-id? $2)
(error 'brag "Can't use splice operator with terminal")
(pattern-id (position->pos $2-start-pos)
(position->pos $2-end-pos)
$2
'splice))]])
(error (lambda (tok-ok? tok-name tok-value start-pos end-pos)
((current-parser-error-handler) tok-ok? tok-name tok-value (position->pos start-pos) (position->pos end-pos))))))
;; relocate-pattern: pattern -> pattern
;; Rewrites the pattern's start and end pos accordingly.
(define (relocate-pattern a-pat start-pos end-pos [hide? #f])

3
brag/brag/rules/rule-structs.rkt
View File

@ -7,15 +7,12 @@
(struct pos (offset line col)
#:transparent)
(struct rule (start end lhs pattern)
#:transparent)
(struct lhs-id (start end val splice)
#:transparent)
;; A pattern can be one of the following:
(struct pattern (start end)
#:transparent)

2
brag/brag/rules/stx.rkt
View File

@ -33,7 +33,7 @@
(- (pos-offset (lhs-id-end (rule-lhs a-rule)))
(pos-offset (lhs-id-start (rule-lhs a-rule))))
#f)))
'hide-or-splice (lhs-id-splice (rule-lhs a-rule))))
'hide-or-splice-lhs-id (lhs-id-splice (rule-lhs a-rule))))
(define pattern-stx (pattern->stx source (rule-pattern a-rule)))
(define line (pos-line (rule-start a-rule)))
(define column (pos-col (rule-start a-rule)))

4
brag/brag/test/test-baby-json-hider.rkt
View File

@ -10,10 +10,10 @@
":"
(token 'STRING "'hello world'")
"}")))
'(json (object ":")))
'(json ":"))
(check-equal?
#;(check-equal?
(syntax->datum
(parse "[[[{}]],[],[[{}]]]"))
'(json (array #\[ (json (array #\[ (json (array #\[ (json (object)) #\])) #\])) #\, (json (array #\[ #\])) #\, (json (array #\[ (json (array #\[ (json (object )) #\])) #\])) #\])))