148 lines
4.7 KiB
Racket
148 lines
4.7 KiB
Racket
#lang racket/base
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(require racket/list
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racket/contract/base
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racket/contract/combinator
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racket/pretty
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"core.rkt")
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(provide
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(contract-out
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[xexpr/c contract?]
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[xexpr? (any/c . -> . boolean?)]
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[validate-xexpr (any/c . -> . (one-of/c #t))]
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[correct-xexpr? (any/c (-> any/c) (exn:invalid-xexpr? . -> . any/c) . -> . any/c)])
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(struct-out exn:invalid-xexpr))
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;; Xexpr ::= String
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;; | (list* Symbol (listof Attribute-srep) (listof Xexpr))
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;; | (cons Symbol (listof Xexpr))
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;; | Symbol
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;; | Nat (WFC: Valid Char)
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;; | Comment
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;; | Processing-instruction
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;; | Cdata
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;; Attribute-srep ::= (list Symbol String)
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;; sorting is no longer necessary, since xt3d uses xml->zxexpr, which sorts.
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(define xexpr-datum/c
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(or/c string? symbol? valid-char?
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comment? p-i? cdata? pcdata?))
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(define (xexpr? x)
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(correct-xexpr? x (lambda () #t) (lambda (exn) #f)))
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(define (validate-xexpr x)
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(correct-xexpr? x (lambda () #t) (lambda (exn) (raise exn))))
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(define xexpr/c
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(make-flat-contract
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#:name 'xexpr?
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#:projection
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(lambda (blame)
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(lambda (val)
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(with-handlers ([exn:invalid-xexpr?
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(lambda (exn)
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(raise-blame-error
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blame
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val
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"Not an Xexpr. ~a\n\nContext:\n~a"
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(exn-message exn)
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(pretty-format val)))])
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(validate-xexpr val)
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val)))
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#:first-order xexpr?))
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;; ;; ;; ;; ;; ;; ;
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;; ; xexpr? helpers
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(define-struct (exn:invalid-xexpr exn:fail) (code))
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;; correct-xexpr? : any (-> a) (exn -> a) -> a
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(define (correct-xexpr? x true false)
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(cond
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((string? x) (true))
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((symbol? x) (true))
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((valid-char? x) (true))
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((comment? x) (true))
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((p-i? x) (true))
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((cdata? x) (true))
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((pcdata? x) (true))
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((list? x)
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(or (null? x)
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(if (symbol? (car x))
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(if (has-attribute? x)
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(and (attribute-pairs? (cadr x) true false)
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(andmap (lambda (part)
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(correct-xexpr? part true false))
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(cddr x))
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(true))
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(andmap (lambda (part)
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(correct-xexpr? part true false))
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(cdr x)))
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(false (make-exn:invalid-xexpr
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(format
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"Expected a symbol as the element name, given ~s"
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(car x))
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(current-continuation-marks)
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x)))))
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[(permissive-xexprs) (true)]
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(else (false
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(make-exn:invalid-xexpr
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(format (string-append
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"Expected a string, symbol, valid numeric entity, comment, "
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"processing instruction, or list, given ~s")
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x)
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(current-continuation-marks)
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x)))))
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;; has-attribute? : List -> Boolean
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;; True if the Xexpr provided has an attribute list.
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(define (has-attribute? x)
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(and (> (length x) 1)
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(list? (cadr x))
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(andmap (lambda (attr)
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(pair? attr))
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(cadr x))))
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;; attribute-pairs? : List (-> a) (exn -> a) -> a
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;; True if the list is a list of pairs.
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(define (attribute-pairs? attrs true false)
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(if (null? attrs)
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(true)
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(let ((attr (car attrs)))
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(if (pair? attr)
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(and (attribute-symbol-string? attr true false)
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(attribute-pairs? (cdr attrs) true false )
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(true))
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(false
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(make-exn:invalid-xexpr
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(format "Expected an attribute pair, given ~s" attr)
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(current-continuation-marks)
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attr))))))
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;; attribute-symbol-string? : List (-> a) (exn -> a) -> a
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;; True if the list is a list of String,Symbol pairs.
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(define (attribute-symbol-string? attr true false)
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(if (symbol? (car attr))
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(if (pair? (cdr attr))
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(if (or (string? (cadr attr))
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(permissive-xexprs))
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(true)
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(false (make-exn:invalid-xexpr
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(format "Expected an attribute value string, given ~v" (cadr attr))
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(current-continuation-marks)
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(cadr attr))))
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(false (make-exn:invalid-xexpr
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(format "Expected an attribute value string for attribute ~s, given nothing" attr)
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(current-continuation-marks)
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attr)))
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(false (make-exn:invalid-xexpr
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(format "Expected an attribute symbol, given ~s" (car attr))
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(current-continuation-marks)
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(cadr attr)))))
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;; ; end xexpr? helpers
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;; ;; ;; ;; ;; ;; ;; ;;
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