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keywords.sls
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keywords.sls
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#!r6rs
;; Copyright 2009 Derick Eddington. My MIT-style license is in the file named
;; LICENSE from the original collection this file is distributed with.
(library (xitomatl keywords)
(export
keywords-parser
case-lambda/kw
lambda/kw
define/kw
keyword-condition?
condition-keyword)
(import
(rnrs)
(only (xitomatl exceptions)
reraise)
(xitomatl keywords parser)
(for (only (xitomatl macro-utils)
with-syntax*
gen-temp)
expand)
(for (xitomatl keywords expand-time)
expand))
(define-syntax keywords-parser
(syntax-rules ()
((_ . r)
(keywords-parser/who "a keywords parser" . r))))
(define-syntax keywords-parser/who
(syntax-rules ()
((_ who . r)
(keywords-parser--meta who eq?
missing-value--default missing-keyword--default predicate-false--default
. r))))
(define (unexpected-additionals--default who addts)
(apply assertion-violation who "unexpected additional arguments" addts))
(define-syntax keywords-parser--clause-failed
(syntax-rules ()
((_ #F . r)
(keywords-parser--meta #F eq?
missing-value--clause-failed
missing-keyword--clause-failed
predicate-false--clause-failed
. r))))
(define clause-failed (list #T)) ;; unique object
(define (clause-failed? x) (eq? x clause-failed))
(define (missing-value--clause-failed who kw-id)
(raise clause-failed))
(define (missing-keyword--clause-failed who kw-id)
(raise clause-failed))
(define (predicate-false--clause-failed who kw-id pred-expr value)
(raise clause-failed))
(define (unexpected-additionals--clause-failed who addts)
(raise clause-failed))
(define (make-case-lambda/kw who procs)
(lambda args
(let ((len (length args)))
(let try-next ((procs procs))
(if (pair? procs)
(if (>= len (caar procs))
((call/cc
(lambda (k)
(with-exception-handler
(lambda (ex)
(if (clause-failed? ex)
(k (lambda () (try-next (cdr procs))))
(reraise ex)))
(lambda ()
(let-values ((vals (apply (cdar procs) args)))
(lambda () (apply values vals))))))))
(try-next (cdr procs)))
(apply assertion-violation who "no clause matches arguments" args))))))
(define-syntax case-lambda/kw--meta
(lambda (stx)
(define (make-proc-stx kw-formals body kw-parser unexpected who)
(with-syntax*
((((pos-id ...) ((kw-id . opts) ...) additional-id ...)
(parse-kw-formals stx kw-formals))
((additional-id body)
(if (positive? (length #'(additional-id ...)))
(list (car #'(additional-id ...)) body)
(let ((t (gen-temp)))
(list t #`((if (null? #,t)
(let () . #,body)
(#,unexpected '#,who #,t))))))))
(list
#`(lambda (pos-id ... . keywords)
(let ((parser (#,kw-parser #,who (kw-id . opts) ...)))
(let-values (((kw-id ... additional-id) (parser keywords)))
. body)))
(length #'(pos-id ...)))))
(syntax-case stx ()
((_ who (kw-formals . body))
(car (make-proc-stx #'kw-formals #'body #'keywords-parser/who
#'unexpected-additionals--default #'who)))
((_ who (kw-formals . body) ...)
(with-syntax
((((proc pos-id-len) ...)
(map (lambda (kwf b)
(make-proc-stx kwf b #'keywords-parser--clause-failed
#'unexpected-additionals--clause-failed #F))
#'(kw-formals ...)
#'(body ...))))
#'(make-case-lambda/kw 'who
(list (cons pos-id-len proc) ...)))))))
(define-syntax case-lambda/kw
(syntax-rules ()
((_ (kw-formals body0 body ...) ...)
(case-lambda/kw--meta "a case-lambda/kw procedure"
(kw-formals body0 body ...) ...))))
(define-syntax lambda/kw
(syntax-rules ()
((_ kw-formals body0 body ...)
(case-lambda/kw--meta "a lambda/kw procedure"
(kw-formals body0 body ...)))))
(define-syntax define/kw
;; Optimized to process keywords at expand time.
(lambda (stx)
(define (gen-stx who)
(lambda (kw-spec kw-value)
(with-syntax (((kw-id . _) kw-spec))
(let-values (((default predicate boolean) (process-options stx kw-spec)))
(cond ((and default predicate)
(list #`(if (not-given? #,kw-value)
#,default
(if (#,predicate #,kw-value)
#,kw-value
(predicate-false--default '#,who 'kw-id
'#,predicate #,kw-value)))
#'(:default #'not-given)))
(default
(list #`(if (not-given? #,kw-value)
#,default
#,kw-value)
#'(:default #'not-given)))
(predicate
(list #`(if (#,predicate #,kw-value)
#,kw-value
(predicate-false--default '#,who 'kw-id
'#,predicate #,kw-value))
'()))
(boolean
(list kw-value #'(:boolean)))
(else
(list kw-value '())))))))
(syntax-case stx ()
((_ (name . kw-formals) . body)
(with-syntax* ((((pos-id ...) ((kw-id . kw-opts) ...) additional-id ...)
(parse-kw-formals stx #'kw-formals))
((kw-value ...) (generate-temporaries #'(kw-id ...)))
(((value-expr kw-stx-opts) ...)
(map (gen-stx #'name)
#'((kw-id . kw-opts) ...)
#'(kw-value ...))))
#'(begin
(define (proc pos-id ... kw-id ... additional-id ...)
. body)
(define (proc/ve pos-id ... kw-value ... additional-id ...)
(letrec* ((kw-id value-expr)
...)
(proc pos-id ... kw-id ... additional-id ...)))
(define first-class
(case-lambda/kw--meta name
(kw-formals
(proc pos-id ... kw-id ... additional-id ...))))
(define-syntax name
(lambda (stx)
(define parser
(keywords-parser--define/kw stx name (kw-id . kw-stx-opts) ...))
(syntax-case stx ()
((_ pos-id ... kw-expr (... ...))
;; NOTE: Only (quote <identifier>) forms are recognized as
;; keywords, unlike run-time processing which recognizes
;; symbol values; and when multiple occurances of a
;; keyword are present, only the last one's expression is
;; evaluated; and additional expressions are evaluated
;; only when the define/kw formals specified taking
;; additionals.
;; TODO?: Always evaluate all expressions?
;; But it would still differ in that only 'kw are recognized.
(with-syntax*
(((kw-expr/ordered (... ...) (additional-expr (... ...)))
(let-values ((v (parser #'(kw-expr (... ...))))) v))
((additional-expr (... ...))
(if (positive? (length '(additional-id ...)))
(list #'(list additional-expr (... ...)))
(if (positive? (length #'(additional-expr (... ...))))
(syntax-violation #F
"unexpected additional expressions"
stx #'(additional-expr (... ...)))
'()))))
#'(proc/ve pos-id ... kw-expr/ordered (... ...)
additional-expr (... ...))))
(id
(identifier? #'id)
#'first-class))))))))))
)