#lang racket/base (require (for-syntax racket/base syntax/stx syntax/private/id-table syntax/keyword racket/syntax syntax/parse/private/minimatch syntax/parse/private/datum-to-expr syntax/parse/private/rep-attrs syntax/parse/private/rep-data syntax/parse/private/rep-patterns "rep.rkt" syntax/parse/private/kws "opt.rkt" "txlift.rkt") syntax/parse/private/keywords racket/syntax racket/stxparam syntax/stx stxparse-info/parse/private/residual ;; keep abs. path "runtime.rkt" stxparse-info/parse/private/runtime-reflect) ;; keep abs. path ;; ============================================================ (provide define-syntax-class define-splicing-syntax-class define-integrable-syntax-class syntax-parse syntax-parser define/syntax-parse syntax-parser/template parser/rhs define-eh-alternative-set (for-syntax rhs->parser)) (begin-for-syntax ;; constant-desc : Syntax -> String/#f (define (constant-desc stx) (syntax-case stx (quote) [(quote datum) (let ([d (syntax-e #'datum)]) (and (string? d) d))] [expr (let ([d (syntax-e #'expr)]) (and (string? d) (free-identifier=? #'#%datum (datum->syntax #'expr '#%datum)) d))])) (define (tx:define-*-syntax-class stx splicing?) (syntax-case stx () [(_ header . rhss) (parameterize ((current-syntax-context stx)) (let-values ([(name formals arity) (let ([p (check-stxclass-header #'header stx)]) (values (car p) (cadr p) (caddr p)))]) (let ([the-rhs (parse-rhs #'rhss splicing? #:context stx #:default-description (symbol->string (syntax-e name)))]) (with-syntax ([name name] [formals formals] [desc (cond [(rhs-description the-rhs) => constant-desc] [else #f])] [parser (generate-temporary (format-symbol "parse-~a" name))] [arity arity] [attrs (rhs-attrs the-rhs)] [commit? (rhs-commit? the-rhs)] [delimit-cut? (rhs-delimit-cut? the-rhs)] [the-rhs-expr (datum->expression the-rhs)]) #`(begin (define-syntax name (stxclass 'name 'arity 'attrs (quote-syntax parser) '#,splicing? (scopts (length 'attrs) 'commit? 'delimit-cut? desc) #f)) (define-values (parser) (parser/rhs name formals attrs the-rhs-expr #,splicing? #,stx)))))))]))) (define-syntax define-syntax-class (lambda (stx) (tx:define-*-syntax-class stx #f))) (define-syntax define-splicing-syntax-class (lambda (stx) (tx:define-*-syntax-class stx #t))) (define-syntax (define-integrable-syntax-class stx) (syntax-case stx (quote) [(_ name (quote description) predicate) (with-syntax ([parser (generate-temporary (format-symbol "parse-~a" (syntax-e #'name)))] [no-arity no-arity]) #'(begin (define-syntax name (stxclass 'name no-arity '() (quote-syntax parser) #f (scopts 0 #t #t 'description) (quote-syntax predicate))) (define (parser x cx pr es undos fh0 cp0 rl success) (if (predicate x) (success fh0 undos) (let ([es (es-add-thing pr 'description #t rl es)]) (fh0 undos (failure* pr es)))))))])) (define-syntax (parser/rhs stx) (syntax-case stx () [(parser/rhs name formals relsattrs the-rhs-expr splicing? ctx) (with-disappeared-uses (let () (define the-rhs (parameterize ((current-syntax-context #'ctx)) (fixup-rhs (syntax-local-eval (syntax-local-introduce #'the-rhs-expr)) (syntax-e #'splicing?) (syntax->datum #'relsattrs)))) (rhs->parser #'name #'formals #'relsattrs the-rhs (syntax-e #'splicing?) #'ctx)))])) (begin-for-syntax (define (rhs->parser name formals relsattrs the-rhs splicing? [ctx #f]) (define-values (transparent? description variants defs commit? delimit-cut?) (match the-rhs [(rhs _ transparent? description variants defs commit? delimit-cut?) (values transparent? description variants defs commit? delimit-cut?)])) (define vdefss (map variant-definitions variants)) (define formals* (rewrite-formals formals #'x #'rl)) (define patterns (map variant-pattern variants)) (define no-fail? (and (not splicing?) ;; FIXME: commit? needed? (patterns-cannot-fail? patterns))) (when no-fail? (log-syntax-parse-debug "(stxclass) cannot fail: ~e" ctx)) (define body (cond [(null? patterns) #'(fail (failure* pr es))] [splicing? (with-syntax ([(alternative ...) (for/list ([pattern (in-list patterns)]) (with-syntax ([pattern pattern] [relsattrs relsattrs] [iattrs (pattern-attrs pattern)] [commit? commit?] [result-pr (if transparent? #'rest-pr #'(ps-pop-opaque rest-pr))]) #'(parse:H x cx rest-x rest-cx rest-pr pattern pr es (variant-success relsattrs iattrs (rest-x rest-cx result-pr) success cp0 commit?))))]) #'(try alternative ...))] [else (with-syntax ([matrix (optimize-matrix (for/list ([pattern (in-list patterns)]) (with-syntax ([iattrs (pattern-attrs pattern)] [relsattrs relsattrs] [commit? commit?]) (pk1 (list pattern) #'(variant-success relsattrs iattrs () success cp0 commit?)))))]) #'(parse:matrix ((x cx pr es)) matrix))])) (with-syntax ([formals* formals*] [(def ...) defs] [((vdef ...) ...) vdefss] [description description] [transparent? transparent?] [delimit-cut? delimit-cut?] [body body]) #`(lambda (x cx pr es undos fh0 cp0 rl success . formals*) (with ([this-syntax x] [this-role rl]) def ... vdef ... ... (#%expression (syntax-parameterize ((this-context-syntax (syntax-rules () [(tbs) (ps-context-syntax pr)]))) (let ([es (es-add-thing pr description 'transparent? rl #,(if no-fail? #'#f #'es))] [pr (if 'transparent? pr (ps-add-opaque pr))]) (with ([fail-handler fh0] [cut-prompt cp0] [undo-stack undos]) ;; Update the prompt, if required ;; FIXME: can be optimized away if no cut exposed within variants (with-maybe-delimit-cut delimit-cut? body)))))))))) (define-syntax (syntax-parse stx) (syntax-case stx () [(syntax-parse stx-expr . clauses) (quasisyntax/loc stx (let ([x (datum->syntax #f stx-expr)]) (with ([this-syntax x]) (parse:clauses x clauses body-sequence #,((make-syntax-introducer) stx)))))])) (define-syntax (syntax-parser stx) (syntax-case stx () [(syntax-parser . clauses) (quasisyntax/loc stx (lambda (x) (let ([x (datum->syntax #f x)]) (with ([this-syntax x]) (parse:clauses x clauses body-sequence #,((make-syntax-introducer) stx))))))])) (define-syntax (syntax-parser/template stx) (syntax-case stx () [(syntax-parser/template ctx . clauses) (quasisyntax/loc stx (lambda (x) (let ([x (datum->syntax #f x)]) (with ([this-syntax x]) (parse:clauses x clauses one-template ctx)))))])) (define-syntax (define/syntax-parse stx) (syntax-case stx () [(define/syntax-parse pattern . rest) (with-disappeared-uses (let-values ([(rest pattern defs) (parse-pattern+sides #'pattern #'rest #:splicing? #f #:decls (new-declenv null) #:context stx)]) (define no-fail? (patterns-cannot-fail? (list pattern))) (let ([expr (syntax-case rest () [( expr ) #'expr] [_ (raise-syntax-error #f "bad syntax" stx)])] [attrs (pattern-attrs pattern)]) (with-syntax ([(a ...) attrs] [(#s(attr name _ _) ...) attrs] [pattern pattern] [es0 (if no-fail? #'#f #'#t)] [(def ...) defs] [expr expr]) #'(defattrs/unpack (a ...) (let* ([x (datum->syntax #f expr)] [cx x] [pr (ps-empty x x)] [es es0] [fh0 (syntax-patterns-fail (normalize-context 'define/syntax-parse '|define/syntax-parse pattern| x))]) (parameterize ((current-syntax-context x)) def ... (#%expression (with ([fail-handler fh0] [cut-prompt fh0] [undo-stack null]) (parse:S x cx pattern pr es (list (attribute name) ...)))))))))))])) ;; ============================================================ #| Parsing protocols: (parse: pr es success-expr) : Ans : x cx : x cx rest-x rest-cx rest-pr : x cx ??? : x cx x is term to parse, usually syntax but can be pair/null (stx-list?) in cdr patterns cx is most recent syntax object: if x must be coerced to syntax, use cx as lexctx and src pr, es are progress and expectstack, respectively rest-x, rest-cx, rest-pr are variable names to bind in context of success-expr (stxclass-parser x cx pr es undos fail-handler cut-prompt role success-proc arg ...) : Ans success-proc: for stxclass, is (fail-handler undos attr-value ... -> Ans) for splicing-stxclass, is (undos fail-handler rest-x rest-cx rest-pr attr-value -> Ans) fail-handler, cut-prompt : undos failure -> Ans Fail-handler is normally represented with stxparam 'fail-handler', but must be threaded through stxclass calls (in through stxclass-parser, out through success-proc) to support backtracking. Cut-prompt is never changed within stxclass or within alternative, so no threading needed. The undo stack is normally represented with stxparam 'undo-stack', but must be threaded through stxclass calls (like fail-handler). A failure handler closes over a base undo stack and receives an extended current undo stack; the failure handler unwinds effects by performing every action in the difference between them and then restores the saved undo stack. Usually sub-patterns processed in tail position, but *can* do non-tail calls for: - ~commit - var of stxclass with ~commit It is also safe to keep normal tail-call protocol and just adjust fail-handler. There is no real benefit to specializing ~commit, since it does not involve creating a success closure. Some optimizations: - commit protocol for stxclasses (but not ~commit, no point) - avoid continue-vs-end choice point in (EH ... . ()) by eager pair check - integrable stxclasses, specialize ellipses of integrable stxclasses - pattern lists that cannot fail set es=#f to disable ExpectStack allocation |# ;; ---- (begin-for-syntax (define (wash stx) (syntax-e stx)) (define (wash-list washer stx) (let ([l (stx->list stx)]) (unless l (raise-type-error 'wash-list "stx-list" stx)) (map washer l))) (define (wash-iattr stx) (with-syntax ([#s(attr name depth syntax?) stx]) (attr #'name (wash #'depth) (wash #'syntax?)))) (define (wash-sattr stx) (with-syntax ([#s(attr name depth syntax?) stx]) (attr (wash #'name) (wash #'depth) (wash #'syntax?)))) (define (wash-iattrs stx) (wash-list wash-iattr stx)) (define (wash-sattrs stx) (wash-list wash-sattr stx)) (define (generate-n-temporaries n) (generate-temporaries (for/list ([i (in-range n)]) (string->symbol (format "g~sx" i)))))) ;; ---- #| Conventions: - rhs : RHS - iattr : IAttr - relsattr : SAttr - splicing? : bool - x : id (var) - cx : id (var, may be shadowed) - pr : id (var, may be shadowed) - es : id (var, may be shadowed) - success : var (bound to success procedure) - k : expr - rest-x, rest-cx, rest-pr : id (to be bound) - fh, cp, rl : id (var) |# (begin-for-syntax (define (rewrite-formals fstx x-id rl-id) (with-syntax ([x x-id] [rl rl-id]) (let loop ([fstx fstx]) (syntax-case fstx () [([kw arg default] . more) (keyword? (syntax-e #'kw)) (cons #'(kw arg (with ([this-syntax x] [this-role rl]) default)) (loop #'more))] [([arg default] . more) (not (keyword? (syntax-e #'kw))) (cons #'(arg (with ([this-syntax x] [this-role rl]) default)) (loop #'more))] [(formal . more) (cons #'formal (loop #'more))] [_ fstx]))))) ;; (with-maybe-delimit-cut bool expr) (define-syntax with-maybe-delimit-cut (syntax-rules () [(wmdc #t k) (with ([cut-prompt fail-handler]) k)] [(wmdc #f k) k])) ;; (variant-success relsattrs variant (also:id ...) success bool) : expr[Ans] (define-syntax (variant-success stx) (syntax-case stx () [(variant-success relsattrs iattrs (also ...) success cp0 commit?) #`(with-maybe-reset-fail commit? cp0 (base-success-expr iattrs relsattrs (also ...) success))])) ;; (with-maybe-reset-fail bool id expr) (define-syntax with-maybe-reset-fail (syntax-rules () [(wmrs #t cp0 k) (with ([fail-handler cp0]) k)] [(wmrs #f cp0 k) k])) ;; (base-success-expr iattrs relsattrs (also:id ...) success) : expr[Ans] (define-syntax (base-success-expr stx) (syntax-case stx () [(base-success-expr iattrs relsattrs (also ...) success) (let ([reliattrs (reorder-iattrs (wash-sattrs #'relsattrs) (wash-iattrs #'iattrs))]) (with-syntax ([(#s(attr name _ _) ...) reliattrs]) #'(success fail-handler undo-stack also ... (attribute name) ...)))])) ;; ---- ;; (parse:clauses x clauses ctx) (define-syntax (parse:clauses stx) (syntax-case stx () [(parse:clauses x clauses body-mode ctx) ;; if templates? is true, expect one form after kwargs in clause, wrap it with syntax ;; otherwise, expect non-empty body sequence (defs and exprs) (with-disappeared-uses (with-txlifts (lambda () (define who (syntax-case #'ctx () [(m . _) (identifier? #'m) #'m] [_ 'syntax-parse])) (define-values (chunks clauses-stx) (parse-keyword-options #'clauses parse-directive-table #:context #'ctx #:no-duplicates? #t)) (define context (options-select-value chunks '#:context #:default #'x)) (define colon-notation? (not (assq '#:disable-colon-notation chunks))) (define track-literals? (or (assq '#:track-literals chunks) (eq? (syntax-e #'body-mode) 'one-template))) (define-values (decls0 defs) (get-decls+defs chunks #:context #'ctx)) ;; for-clause : stx -> (values pattern stx (listof stx)) (define (for-clause clause) (syntax-case clause () [[p . rest] (let-values ([(rest pattern defs2) (parameterize ((stxclass-colon-notation? colon-notation?)) (parse-pattern+sides #'p #'rest #:splicing? #f #:decls decls0 #:context #'ctx))]) (let ([body-expr (case (syntax-e #'body-mode) ((one-template) (syntax-case rest () [(template) #'(syntax template)] [_ (raise-syntax-error #f "expected exactly one template" #'ctx)])) ((body-sequence) (syntax-case rest () [(e0 e ...) ;; Should we use a shadower (works on the whole file, unhygienically), ;; or use the context of the syntax-parse identifier? (let ([the-#%intdef-begin (datum->syntax #'ctx '#%intdef-begin)]) (if (syntax-local-value the-#%intdef-begin (λ () #f)) ;; Defined as a macro #`(let () (#,the-#%intdef-begin e0 e ...)) #'(let () e0 e ...)))] [_ (raise-syntax-error #f "expected non-empty clause body" #'ctx clause)])) (else (raise-syntax-error #f "internal error: unknown body mode" #'ctx #'body-mode)))]) (values pattern body-expr defs2)))] [_ (raise-syntax-error #f "expected clause" #'ctx clause)])) (define (wrap-track-literals stx) (if track-literals? (quasisyntax/loc stx (track-literals '#,who #,stx)) stx)) (unless (stx-list? clauses-stx) (raise-syntax-error #f "expected sequence of clauses" #'ctx)) (define-values (patterns body-exprs defs2s) (for/lists (patterns body-exprs defs2s) ([clause (in-list (stx->list clauses-stx))]) (for-clause clause))) (define no-fail? (patterns-cannot-fail? patterns)) (when no-fail? (log-syntax-parse-debug "cannot fail: ~e" #'ctx)) (with-syntax ([(def ...) (apply append (get-txlifts-as-definitions) defs defs2s)]) #`(let* ([ctx0 (normalize-context '#,who #,context x)] [pr (ps-empty x (cadr ctx0))] [es #,(if no-fail? #'#f #'#t)] [cx x] [fh0 (syntax-patterns-fail ctx0)]) def ... (parameterize ((current-syntax-context (cadr ctx0)) (current-state '#hasheq()) (current-state-writable? #f)) #,(wrap-track-literals #`(with ([fail-handler fh0] [cut-prompt fh0] [undo-stack null]) #,(cond [(pair? patterns) (with-syntax ([matrix (optimize-matrix (for/list ([pattern (in-list patterns)] [body-expr (in-list body-exprs)]) (pk1 (list pattern) body-expr)))]) #'(parse:matrix ((x cx pr es)) matrix)) #| (with-syntax ([(alternative ...) (for/list ([pattern (in-list patterns)] [body-expr (in-list body-exprs)]) #`(parse:S x cx #,pattern pr es #,body-expr))]) #`(try alternative ...)) |#] [else #`(fail (failure* pr es))])))))))))])) ;; ---- ;; (parse:matrix ((x cx pr es) ...) (PK ...)) : expr[Ans] ;; (parse:matrix (in1 ... inN) (#s(pk1 (P11 ... P1N) e1) ... #s(pk1 (PM1 ... PMN) eM))) ;; represents the matching matrix ;; [_in1_..._inN_|____] ;; [ P11 ... P1N | e1 ] ;; [ : : | : ] ;; [ PM1 ... PMN | eM ] (define-syntax (parse:matrix stx) (syntax-case stx () [(parse:matrix ins (pk ...)) #'(try (parse:pk ins pk) ...)])) (define-syntax (parse:pk stx) (syntax-case stx () [(parse:pk () #s(pk1 () k)) #'k] [(parse:pk ((x cx pr es) . ins) #s(pk1 (pat1 . pats) k)) #'(parse:S x cx pat1 pr es (parse:pk ins #s(pk1 pats k)))] [(parse:pk ((x cx pr es) . ins) #s(pk/same pat1 inner)) #'(parse:S x cx pat1 pr es (parse:matrix ins inner))] [(parse:pk ((x cx pr es) . ins) #s(pk/pair inner)) #'(let-values ([(datum tcx) (if (syntax? x) (values (syntax-e x) x) (values x cx))]) (if (pair? datum) (let ([hx (car datum)] [hcx (car datum)] [hpr (ps-add-car pr)] [tx (cdr datum)] [tpr (ps-add-cdr pr)]) (parse:matrix ((hx hcx hpr es) (tx tcx tpr es) . ins) inner)) (let ([es* (if (null? datum) (es-add-proper-pair (first-desc:matrix inner) es) es)]) (fail (failure* pr es*)))))] [(parse:pk (in1 . ins) #s(pk/and inner)) #'(parse:matrix (in1 in1 . ins) inner)])) (define-syntax (first-desc:matrix stx) (syntax-case stx () [(fdm (#s(pk1 (pat1 . pats) k))) #'(first-desc:S pat1)] [(fdm (#s(pk/same pat1 pks))) #'(first-desc:S pat1)] [(fdm (pk ...)) ;; FIXME #'#f])) ;; ---- ;; (parse:S x cx S-pattern pr es k) : expr[Ans] ;; In k: attrs(S-pattern) are bound. (define-syntax (parse:S stx) (syntax-case stx () [(parse:S x cx pattern0 pr es k) (syntax-case #'pattern0 () [#s(pat:seq-end) #`(k x cx pr)] [#s(pat:any) #'k] [#s(pat:svar name) #'(let-attributes ([#s(attr name 0 #t) (datum->syntax cx x cx)]) k)] [#s(pat:var/p name parser argu (nested-a ...) role #s(scopts attr-count commit? _delimit? _desc)) (with-syntax ([(av ...) (generate-n-temporaries (syntax-e #'attr-count))] [(name-attr ...) (if (identifier? #'name) #'([#s(attr name 0 #t) (datum->syntax cx x cx)]) #'())]) (if (not (syntax-e #'commit?)) ;; The normal protocol #'(app-argu parser x cx pr es undo-stack fail-handler cut-prompt role (lambda (fh undos av ...) (let-attributes (name-attr ...) (let-attributes* ((nested-a ...) (av ...)) (with ([fail-handler fh] [undo-stack undos]) k)))) argu) ;; The commit protocol ;; (Avoids putting k in procedure) #'(let-values ([(fs undos av ...) (with ([fail-handler (lambda (undos fs) (unwind-to undos undo-stack) (values fs undo-stack (let ([av #f]) av) ...))]) (with ([cut-prompt fail-handler]) (app-argu parser x cx pr es undo-stack fail-handler cut-prompt role (lambda (fh undos av ...) (values #f undos av ...)) argu)))]) (if fs (fail fs) (let-attributes (name-attr ...) (let-attributes* ((nested-a ...) (av ...)) (with ([undo-stack undos]) k)))))))] [#s(pat:reflect obj argu attr-decls name (nested-a ...)) (with-syntax ([(name-attr ...) (if (identifier? #'name) #'([#s(attr name 0 #t) (datum->syntax cx x cx)]) #'())]) (with-syntax ([arity (arguments->arity (syntax->datum #'argu))]) #'(let ([parser (reflect-parser obj 'arity 'attr-decls #f)]) (app-argu parser x cx pr es undo-stack fail-handler cut-prompt #f (lambda (fh undos . result) (let-attributes (name-attr ...) (let/unpack ((nested-a ...) result) (with ([fail-handler fh] [undo-stack undos]) k)))) argu))))] [#s(pat:datum datum) (with-syntax ([unwrap-x (if (atomic-datum-stx? #'datum) #'(if (syntax? x) (syntax-e x) x) #'(syntax->datum (datum->syntax #f x)))]) #`(let ([d unwrap-x]) (if (equal? d (quote datum)) k (fail (failure* pr (es-add-atom 'datum es))))))] [#s(pat:literal literal input-phase lit-phase) #`(if (and (identifier? x) (free-identifier=? x (quote-syntax literal) input-phase lit-phase)) (with ([undo-stack (cons (current-state) undo-stack)]) (state-cons! 'literals x) k) (fail (failure* pr (es-add-literal (quote-syntax literal) es))))] [#s(pat:action action subpattern) #'(parse:A x cx action pr es (parse:S x cx subpattern pr es k))] [#s(pat:head head tail) #`(parse:H x cx rest-x rest-cx rest-pr head pr es (parse:S rest-x rest-cx tail rest-pr es k))] [#s(pat:dots head tail) #`(parse:dots x cx head tail pr es k)] [#s(pat:and subpatterns) (for/fold ([k #'k]) ([subpattern (in-list (reverse (syntax->list #'subpatterns)))]) #`(parse:S x cx #,subpattern pr es #,k))] [#s(pat:or (a ...) (subpattern ...) (subattrs ...)) (with-syntax ([(#s(attr id _ _) ...) #'(a ...)]) #`(let ([success (lambda (fh undos id ...) (let-attributes ([a id] ...) (with ([fail-handler fh] [undo-stack undos]) k)))]) (try (parse:S x cx subpattern pr es (disjunct subattrs success () (id ...))) ...)))] [#s(pat:not subpattern) #`(let* ([fh0 fail-handler] [pr0 pr] [es0 es] [fail-to-succeed (lambda (undos fs) (unwind-to undos undo-stack) k)]) ;; ~not implicitly prompts to be safe, ;; but ~! not allowed within ~not (unless within ~delimit-cut, etc) ;; (statically checked!) (with ([fail-handler fail-to-succeed] [cut-prompt fail-to-succeed]) ;; to be safe (parse:S x cx subpattern pr es (fh0 undo-stack (failure* pr0 es0)))))] [#s(pat:pair head tail) #`(let ([datum (if (syntax? x) (syntax-e x) x)] [cx (if (syntax? x) x cx)]) ;; FIXME: shadowing cx?! (if (pair? datum) (let ([hx (car datum)] [hcx (car datum)] [hpr (ps-add-car pr)] [tx (cdr datum)] [tpr (ps-add-cdr pr)]) (parse:S hx hcx head hpr es (parse:S tx cx tail tpr es k))) (let ([es* (if (null? datum) (es-add-proper-pair (first-desc:S head) es) es)]) (fail (failure* pr es*)))))] [#s(pat:vector subpattern) #`(let ([datum (if (syntax? x) (syntax-e x) x)]) (if (vector? datum) (let ([datum (vector->list datum)] [vcx (if (syntax? x) x cx)] ;; FIXME: (vector? datum) => (syntax? x) ??? [pr* (ps-add-unvector pr)]) (parse:S datum vcx subpattern pr* es k)) (fail (failure* pr es))))] [#s(pat:box subpattern) #`(let ([datum (if (syntax? x) (syntax-e x) x)]) (if (box? datum) (let ([datum (unbox datum)] [bcx (if (syntax? x) x cx)] ;; FIXME: (box? datum) => (syntax? x) ??? [pr* (ps-add-unbox pr)]) (parse:S datum bcx subpattern pr* es k)) (fail (failure* pr es))))] [#s(pat:pstruct key subpattern) #`(let ([datum (if (syntax? x) (syntax-e x) x)]) (if (let ([xkey (prefab-struct-key datum)]) (and xkey (equal? xkey 'key))) (let ([datum (cdr (vector->list (struct->vector datum)))] [scx (if (syntax? x) x cx)] ;; FIXME: (struct? datum) => (syntax? x) ??? [pr* (ps-add-unpstruct pr)]) (parse:S datum scx subpattern pr* es k)) (fail (failure* pr es))))] [#s(pat:describe pattern description transparent? role) #`(let ([es* (es-add-thing pr description transparent? role es)] [pr* (if 'transparent? pr (ps-add-opaque pr))]) (parse:S x cx pattern pr* es* k))] [#s(pat:delimit pattern) #`(let ([cp0 cut-prompt]) (with ([cut-prompt fail-handler]) (parse:S x cx pattern pr es (with ([cut-prompt cp0]) k))))] [#s(pat:commit pattern) #`(let ([fh0 fail-handler] [cp0 cut-prompt]) (with ([cut-prompt fh0]) (parse:S x cx pattern pr es (with ([cut-prompt cp0] [fail-handler fh0]) k))))] [#s(pat:ord pattern group index) #`(let ([pr* (ps-add pr '#s(ord group index))]) (parse:S x cx pattern pr* es k))] [#s(pat:post pattern) #`(let ([pr* (ps-add-post pr)]) (parse:S x cx pattern pr* es k))] [#s(pat:integrated name predicate description role) (with-syntax ([(name-attr ...) (if (identifier? #'name) #'([#s(attr name 0 #t) x*]) #'())]) #'(let ([x* (datum->syntax cx x cx)]) (if (predicate x*) (let-attributes (name-attr ...) k) (let ([es* (es-add-thing pr 'description #t role es)]) (fail (failure* pr es*))))))] [_ (wrong-syntax stx "internal error: bad S pattern: ~e" #'pattern0)])])) ;; (first-desc:S S-pattern) : expr[FirstDesc] (define-syntax (first-desc:S stx) (syntax-case stx () [(fds p) (syntax-case #'p () [#s(pat:any) #''(any)] [#s(pat:svar name) #''(any)] [#s(pat:var/p _ _ _ _ _ #s(scopts _ _ _ desc)) #'(quote desc)] [#s(pat:datum d) #''(datum d)] [#s(pat:literal id _ip _lp) #''(literal id)] [#s(pat:describe _p desc _t? _role) #`(quote #,(or (constant-desc #'desc) #'#f))] [#s(pat:delimit pattern) #'(first-desc:S pattern)] [#s(pat:commit pattern) #'(first-desc:S pattern)] [#s(pat:ord pattern _ _) #'(first-desc:S pattern)] [#s(pat:post pattern) #'(first-desc:S pattern)] [#s(pat:integrated _name _pred description _role) #''description] [_ #'#f])])) ;; (first-desc:H HeadPattern) : Expr (define-syntax (first-desc:H stx) (syntax-case stx () [(fdh hpat) (syntax-case #'hpat () [#s(hpat:single sp) #'(first-desc:S sp)] [#s(hpat:var/p _ _ _ _ _ #s(scopts _ _ _ desc)) #'(quote desc)] [#s(hpat:seq lp) #'(first-desc:L lp)] [#s(hpat:describe _hp desc _t? _r) #`(quote #,(or (constant-desc #'desc) #'#f))] [#s(hpat:delimit hp) #'(first-desc:H hp)] [#s(hpat:commit hp) #'(first-desc:H hp)] [#s(hpat:ord hp _ _) #'(first-desc:H hp)] [#s(hpat:post hp) #'(first-desc:H hp)] [_ #'#f])])) (define-syntax (first-desc:L stx) (syntax-case stx () [(fdl lpat) (syntax-case #'lpat () [#s(pat:pair sp lp) #'(first-desc:S sp)] [_ #'#f])])) ;; (disjunct (iattr ...) success (pre:expr ...) (id:id ...)) : expr[Ans] (define-syntax (disjunct stx) (syntax-case stx () [(disjunct (#s(attr sub-id _ _) ...) success (pre ...) (id ...)) (with-syntax ([(alt-sub-id ...) (generate-temporaries #'(sub-id ...))]) #`(let ([alt-sub-id (attribute sub-id)] ...) (let ([id #f] ...) (let ([sub-id alt-sub-id] ...) (success fail-handler undo-stack pre ... id ...)))))])) ;; (parse:A x cx A-pattern pr es k) : expr[Ans] ;; In k: attrs(A-pattern) are bound. (define-syntax (parse:A stx) (syntax-case stx () [(parse:A x cx pattern0 pr es k) (syntax-case #'pattern0 () [#s(action:and (action ...)) (for/fold ([k #'k]) ([action (in-list (reverse (syntax->list #'(action ...))))]) #`(parse:A x cx #,action pr es #,k))] [#s(action:cut) #'(with ([fail-handler cut-prompt]) k)] [#s(action:bind a expr) #'(let-attributes ([a (wrap-user-code expr)]) k)] [#s(action:fail condition message) #`(let ([c (wrap-user-code condition)]) (if c (let ([pr* (if (syntax? c) (ps-add-stx pr c) pr)] [es* (es-add-message message es)]) (fail (failure* pr* es*))) k))] [#s(action:parse pattern expr) #`(let* ([y (datum->syntax/with-clause (wrap-user-code expr))] [cy y] [pr* (ps-add-stx pr y)]) (parse:S y cy pattern pr* es k))] [#s(action:do (stmt ...)) #'(parameterize ((current-state-writable? #t)) (let ([init-state (current-state)]) (no-shadow stmt) ... (parameterize ((current-state-writable? #f)) (with ([undo-stack (maybe-add-state-undo init-state (current-state) undo-stack)]) (#%expression k)))))] [#s(action:undo (stmt ...)) #'(with ([undo-stack (cons (lambda () stmt ... (void)) undo-stack)] [cut-prompt illegal-cut-error]) k)] [#s(action:ord pattern group index) #'(let ([pr* (ps-add pr '#s(ord group index))]) (parse:A x cx pattern pr* es k))] [#s(action:post pattern) #'(let ([pr* (ps-add-post pr)]) (parse:A x cx pattern pr* es k))] [_ (wrong-syntax stx "internal error: bad A pattern: ~e" #'pattern0)])])) ;; (parse:H x cx rest-x rest-cx rest-pr H-pattern pr es k) ;; In k: rest, rest-pr, attrs(H-pattern) are bound. (define-syntax (parse:H stx) (syntax-case stx () [(parse:H x cx rest-x rest-cx rest-pr head pr es k) (syntax-case #'head () [#s(hpat:single pattern) #'(parse:S x cx ;; FIXME: consider proper-list-pattern? (yes is consistent with ~seq) #s(pat:pair pattern #s(pat:seq-end)) pr es (lambda (rest-x rest-cx rest-pr) k))] [#s(hpat:describe pattern description transparent? role) #`(let ([es* (es-add-thing pr description transparent? role es)] [pr* (if 'transparent? pr (ps-add-opaque pr))]) (parse:H x cx rest-x rest-cx rest-pr pattern pr* es* (let ([rest-pr (if 'transparent? rest-pr (ps-pop-opaque rest-pr))]) k)))] [#s(hpat:var/p name parser argu (nested-a ...) role #s(scopts attr-count commit? _delimit? _desc)) (with-syntax ([(av ...) (generate-n-temporaries (syntax-e #'attr-count))] [(name-attr ...) (if (identifier? #'name) #'([#s(attr name 0 #t) (stx-list-take x (ps-difference pr rest-pr))]) #'())]) (if (not (syntax-e #'commit?)) ;; The normal protocol #`(app-argu parser x cx pr es undo-stack fail-handler cut-prompt role (lambda (fh undos rest-x rest-cx rest-pr av ...) (let-attributes (name-attr ...) (let-attributes* ((nested-a ...) (av ...)) (with ([fail-handler fh] [undo-stack undos]) k)))) argu) ;; The commit protocol ;; (Avoids putting k in procedure) #'(let-values ([(fs undos rest-x rest-cx rest-pr av ...) (with ([fail-handler (lambda (undos fs) (unwind-to undos undo-stack) (values fs undo-stack #f #f #f (let ([av #f]) av) ...))]) (with ([cut-prompt fail-handler]) (app-argu parser x cx pr es undo-stack fail-handler cut-prompt role (lambda (fh undos rest-x rest-cx rest-pr av ...) (values #f undos rest-x rest-cx rest-pr av ...)) argu)))]) (if fs (fail fs) (let-attributes (name-attr ...) (let-attributes* ((nested-a ...) (av ...)) (with ([undo-stack undos]) k)))))))] [#s(hpat:reflect obj argu attr-decls name (nested-a ...)) (with-syntax ([(name-attr ...) (if (identifier? #'name) #'([#s(attr name 0 #t) (stx-list-take x (ps-difference pr rest-pr))]) #'())]) (with-syntax ([arity (arguments->arity (syntax->datum #'argu))]) #'(let ([parser (reflect-parser obj 'arity 'attr-decls #t)]) (app-argu parser x cx pr es undo-stack fail-handler cut-prompt #f (lambda (fh undos rest-x rest-cx rest-pr . result) (let-attributes (name-attr ...) (let/unpack ((nested-a ...) result) (with ([fail-handler fh] [undo-stack undos]) k)))) argu))))] [#s(hpat:and head single) #`(let ([cx0 cx]) (parse:H x cx rest-x rest-cx rest-pr head pr es (let ([lst (stx-list-take x (ps-difference pr rest-pr))]) (parse:S lst cx0 single pr es k))))] [#s(hpat:or (a ...) (subpattern ...) (subattrs ...)) (with-syntax ([(#s(attr id _ _) ...) #'(a ...)]) #`(let ([success (lambda (fh undos rest-x rest-cx rest-pr id ...) (let-attributes ([a id] ...) (with ([fail-handler fh] [undo-stack undos]) k)))]) (try (parse:H x cx rest-x rest-cx rest-pr subpattern pr es (disjunct subattrs success (rest-x rest-cx rest-pr) (id ...))) ...)))] [#s(hpat:seq pattern) #'(parse:S x cx pattern pr es (lambda (rest-x rest-cx rest-pr) k))] [#s(hpat:action action subpattern) #'(parse:A x cx action pr es (parse:H x cx rest-x rest-cx rest-pr subpattern pr es k))] [#s(hpat:delimit pattern) #'(let ([cp0 cut-prompt]) (with ([cut-prompt fail-handler]) (parse:H x cx rest-x rest-cx rest-pr pattern pr es (with ([cut-prompt cp0]) k))))] [#s(hpat:commit pattern) #`(let ([fh0 fail-handler] [cp0 cut-prompt]) (with ([cut-prompt fh0]) (parse:H x cx rest-x rest-cx rest-pr pattern pr es (with ([cut-prompt cp0] [fail-handler fh0]) k))))] [#s(hpat:ord pattern group index) #`(let ([pr* (ps-add pr '#s(ord group index))]) (parse:H x cx rest-x rest-cx rest-pr pattern pr* es (let ([rest-pr (ps-pop-ord rest-pr)]) k)))] [#s(hpat:post pattern) #'(let ([pr* (ps-add-post pr)]) (parse:H x cx rest-x rest-cx rest-pr pattern pr* es (let ([rest-pr (ps-pop-post rest-pr)]) k)))] [#s(hpat:peek pattern) #`(let ([saved-x x] [saved-cx cx] [saved-pr pr]) (parse:H x cx dummy-x dummy-cx dummy-pr pattern pr es (let ([rest-x saved-x] [rest-cx saved-cx] [rest-pr saved-pr]) k)))] [#s(hpat:peek-not subpattern) #`(let* ([fh0 fail-handler] [pr0 pr] [es0 es] [fail-to-succeed (lambda (undos fs) (unwind-to undos undo-stack) (let ([rest-x x] [rest-cx cx] [rest-pr pr]) k))]) ;; ~not implicitly prompts to be safe, ;; but ~! not allowed within ~not (unless within ~delimit-cut, etc) ;; (statically checked!) (with ([fail-handler fail-to-succeed] [cut-prompt fail-to-succeed]) ;; to be safe (parse:H x cx rest-x rest-cx rest-pr subpattern pr es (fh0 undo-stack (failure* pr0 es0)))))] [_ (wrong-syntax stx "internal error: bad H pattern: ~e" #'head)])])) ;; (parse:dots x cx EH-pattern S-pattern pr es k) : expr[Ans] ;; In k: attrs(EH-pattern, S-pattern) are bound. (define-syntax (parse:dots stx) (syntax-case stx () ;; == Specialized cases ;; -- (x ... . ()) [(parse:dots x cx (#s(ehpat (attr0) #s(hpat:single #s(pat:svar name)) #f #f)) #s(pat:datum ()) pr es k) #'(let-values ([(status result) (predicate-ellipsis-parser x cx pr es void #f #f)]) (case status ((ok) (let-attributes ([attr0 result]) k)) (else (fail result))))] ;; -- (x:sc ... . ()) where sc is an integrable stxclass like id or expr [(parse:dots x cx (#s(ehpat (attr0) #s(hpat:single #s(pat:integrated _name pred? desc role)) #f #f)) #s(pat:datum ()) pr es k) #'(let-values ([(status result) (predicate-ellipsis-parser x cx pr es pred? desc role)]) (case status ((ok) (let-attributes ([attr0 result]) k)) (else (fail result))))] ;; -- (x:sc ... . ()) where sc is a stxclass with commit ;; Since head pattern does commit, no need to thread fail-handler, cut-prompt through. ;; Microbenchmark suggests this isn't a useful specialization ;; (probably try-or-pair/null-check already does the useful part) ;; == General case [(parse:dots x cx (#s(ehpat head-attrs head head-repc check-null?) ...) tail pr es k) (let () (define repcs (wash-list wash #'(head-repc ...))) (define rep-ids (for/list ([repc (in-list repcs)]) (and repc (generate-temporary 'rep)))) (define rel-repcs (filter values repcs)) (define rel-rep-ids (filter values rep-ids)) (define rel-heads (for/list ([head (in-list (syntax->list #'(head ...)))] [repc (in-list repcs)] #:when repc) head)) (define aattrs (for/list ([head-attrs (in-list (syntax->list #'(head-attrs ...)))] [repc (in-list repcs)] #:when #t [a (in-list (wash-iattrs head-attrs))]) (cons a repc))) (define attrs (map car aattrs)) (define attr-repcs (map cdr aattrs)) (define ids (map attr-name attrs)) (define tail-pattern-is-null? (equal? (syntax->datum #'tail) '#s(pat:datum ()))) (with-syntax ([(id ...) ids] [(alt-id ...) (generate-temporaries ids)] [reps rel-rep-ids] [(head-rep ...) rep-ids] [(rel-rep ...) rel-rep-ids] [(rel-repc ...) rel-repcs] [(rel-head ...) rel-heads] [(a ...) attrs] [(attr-repc ...) attr-repcs] [do-pair/null? ;; FIXME: do pair/null check only if no nullable head patterns ;; (and tail-pattern-is-null? (andmap not (syntax->datum #'(nullable? ...)))) tail-pattern-is-null?]) (define/with-syntax alt-map #'((id . alt-id) ...)) (define/with-syntax loop-k #'(dots-loop dx* dcx* loop-pr* undo-stack fail-handler rel-rep ... alt-id ...)) #`(let () ;; dots-loop : stx progress rel-rep ... alt-id ... -> Ans (define (dots-loop dx dcx loop-pr undos fh rel-rep ... alt-id ...) (with ([fail-handler fh] [undo-stack undos]) (try-or-pair/null-check do-pair/null? dx dcx loop-pr es (try (parse:EH dx dcx loop-pr head-attrs check-null? head-repc dx* dcx* loop-pr* alt-map head-rep head es loop-k) ...) (cond [(< rel-rep (rep:min-number rel-repc)) (let ([es (expectation-of-reps/too-few es rel-rep rel-repc rel-head)]) (fail (failure* loop-pr es)))] ... [else (let-attributes ([a (rep:finalize a attr-repc alt-id)] ...) (parse:S dx dcx tail loop-pr es k))])))) (let ([rel-rep 0] ... [alt-id (rep:initial-value attr-repc)] ...) (dots-loop x cx pr undo-stack fail-handler rel-rep ... alt-id ...)))))])) ;; (try-or-pair/null-check bool x cx es pr pair-alt maybe-null-alt) (define-syntax try-or-pair/null-check (syntax-rules () [(topc #t x cx pr es pair-alt null-alt) (cond [(stx-pair? x) pair-alt] [(stx-null? x) null-alt] [else (fail (failure* pr es))])] [(topc _ x cx pr es alt1 alt2) (try alt1 alt2)])) ;; (parse:EH x cx pr repc x* cx* pr* alts rep H-pattern es k) : expr[Ans] ;; In k: x*, cx*, pr*, alts`attrs(H-pattern) are bound and rep is shadowed. (define-syntax (parse:EH stx) (syntax-case stx () [(parse:EH x cx pr attrs check-null? repc x* cx* pr* alts rep head es k) (let () (define/with-syntax k* (let* ([main-attrs (wash-iattrs #'attrs)] [ids (map attr-name main-attrs)] [alt-ids (let ([table (make-bound-id-table)]) (for ([entry (in-list (syntax->list #'alts))]) (let ([entry (syntax-e entry)]) (bound-id-table-set! table (car entry) (cdr entry)))) (for/list ([id (in-list ids)]) (bound-id-table-ref table id)))]) (with-syntax ([(id ...) ids] [(alt-id ...) alt-ids]) #`(let ([alt-id (rep:combine repc (attribute id) alt-id)] ...) #,(if (syntax->datum #'check-null?) #'(if (zero? (ps-difference pr pr*)) (error/null-eh-match) k) #'k))))) (syntax-case #'repc () [#f #`(parse:H x cx x* cx* pr* head pr es k*)] [_ #`(parse:H x cx x* cx* pr* head pr es (if (< rep (rep:max-number repc)) (let ([rep (add1 rep)]) k*) (let ([es* (expectation-of-reps/too-many es rep repc)]) (fail (failure* pr* es*)))))]))])) ;; (rep:initial-value RepConstraint) : expr (define-syntax (rep:initial-value stx) (syntax-case stx () [(_ #s(rep:once _ _ _)) #'#f] [(_ #s(rep:optional _ _ _)) #'#f] [(_ _) #'null])) ;; (rep:finalize RepConstraint expr) : expr (define-syntax (rep:finalize stx) (syntax-case stx () [(_ a #s(rep:optional _ _ defaults) v) (with-syntax ([#s(attr name _ _) #'a] [(#s(action:bind da de) ...) #'defaults]) (let ([default (for/or ([da (in-list (syntax->list #'(da ...)))] [de (in-list (syntax->list #'(de ...)))]) (with-syntax ([#s(attr dname _ _) da]) (and (bound-identifier=? #'name #'dname) de)))]) (if default #`(or v #,default) #'v)))] [(_ a #s(rep:once _ _ _) v) #'v] [(_ a _ v) #'(reverse v)])) ;; (rep:min-number RepConstraint) : expr (define-syntax (rep:min-number stx) (syntax-case stx () [(_ #s(rep:once _ _ _)) #'1] [(_ #s(rep:optional _ _ _)) #'0] [(_ #s(rep:bounds min max _ _ _)) #'min])) ;; (rep:max-number RepConstraint) : expr (define-syntax (rep:max-number stx) (syntax-case stx () [(_ #s(rep:once _ _ _)) #'1] [(_ #s(rep:optional _ _ _)) #'1] [(_ #s(rep:bounds min max _ _ _)) #'max])) ;; (rep:combine RepConstraint expr expr) : expr (define-syntax (rep:combine stx) (syntax-case stx () [(_ #s(rep:once _ _ _) a b) #'a] [(_ #s(rep:optional _ _ _) a b) #'a] [(_ _ a b) #'(cons a b)])) ;; ---- (define-syntax expectation-of-reps/too-few (syntax-rules () [(_ es rep #s(rep:once name too-few-msg too-many-msg) hpat) (cond [(or too-few-msg (name->too-few/once name)) => (lambda (msg) (es-add-message msg es))] [(first-desc:H hpat) => (lambda (fd) (es-add-proper-pair fd es))] [else es])] [(_ es rep #s(rep:optional name too-many-msg _) hpat) (error 'syntax-parse "INTERNAL ERROR: impossible (too-few)")] [(_ es rep #s(rep:bounds min max name too-few-msg too-many-msg) hpat) (cond [(or too-few-msg (name->too-few name)) => (lambda (msg) (es-add-message msg es))] [(first-desc:H hpat) => (lambda (fd) (es-add-proper-pair fd es))] [else es])])) (define-syntax expectation-of-reps/too-many (syntax-rules () [(_ es rep #s(rep:once name too-few-msg too-many-msg)) (es-add-message (or too-many-msg (name->too-many name)) es)] [(_ es rep #s(rep:optional name too-many-msg _)) (es-add-message (or too-many-msg (name->too-many name)) es)] [(_ es rep #s(rep:bounds min max name too-few-msg too-many-msg)) (es-add-message (or too-many-msg (name->too-many name)) es)])) ;; ==== (define-syntax (define-eh-alternative-set stx) (define (parse-alt x) (syntax-case x (pattern) [(pattern alt) #'alt] [else (wrong-syntax x "expected eh-alternative-set alternative")])) (parameterize ((current-syntax-context stx)) (syntax-case stx () [(_ name a ...) (unless (identifier? #'name) (wrong-syntax #'name "expected identifier")) (let* ([alts (map parse-alt (syntax->list #'(a ...)))] [decls (new-declenv null #:conventions null)] [ehpat+hstx-list (apply append (for/list ([alt (in-list alts)]) (parse-EH-variant alt decls #t #:context stx)))] [eh-alt+defs-list (for/list ([ehpat+hstx (in-list ehpat+hstx-list)]) (let ([ehpat (car ehpat+hstx)] [hstx (cadr ehpat+hstx)]) (cond [(syntax? hstx) (define the-pattern (ehpat-head ehpat)) (define attrs (iattrs->sattrs (pattern-attrs the-pattern))) (define the-variant (variant hstx attrs the-pattern null)) (define the-rhs (rhs attrs #t #f (list the-variant) null #f #f)) (with-syntax ([(parser) (generate-temporaries '(eh-alt-parser))] [the-rhs-expr (datum->expression the-rhs)]) (list (eh-alternative (ehpat-repc ehpat) attrs #'parser) (list #`(define parser (parser/rhs parser () #,attrs the-rhs-expr #t #,stx)))))] [(eh-alternative? hstx) (list hstx null)] [else (error 'define-eh-alternative-set "internal error: unexpected ~e" hstx)])))] [eh-alts (map car eh-alt+defs-list)] [defs (apply append (map cadr eh-alt+defs-list))]) (with-syntax ([(def ...) defs] [(alt-expr ...) (for/list ([alt (in-list eh-alts)]) (with-syntax ([repc-expr (datum->expression (eh-alternative-repc alt))] [attrs-expr #`(quote #,(eh-alternative-attrs alt))] [parser-expr #`(quote-syntax #,(eh-alternative-parser alt))]) #'(eh-alternative repc-expr attrs-expr parser-expr)))]) #'(begin def ... (define-syntax name (eh-alternative-set (list alt-expr ...))))))])))