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59 lines
2.1 KiB
Racket
59 lines
2.1 KiB
Racket
#lang debug racket/base
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(require racket/contract racket/match (for-syntax racket/base racket/syntax))
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(provide (all-defined-out))
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(struct $point (x y) #:transparent #:mutable)
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(struct $size (width height) #:transparent #:mutable)
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(struct $rect (origin size) #:transparent #:mutable)
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(define current-wrap-width (make-parameter 5))
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(define current-page-size (make-parameter ($size 10 10)))
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(define (list-of proc) (λ (x) (and (list? x) (andmap proc x))))
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(struct quad (tag attrs elems) #:transparent #:mutable
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#:constructor-name quad-constructor
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#:guard (λ (tag attrs elems name)
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(unless (match (list tag attrs elems)
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[(list (? quad-tag?)
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(? quad-attrs?)
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(? quad-elems?)) #true]
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[_ #false])
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(error 'no-dice))
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(values tag attrs elems)))
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(define (quad-tag? x) (match x
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[(or (? symbol?) #false) #true]
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[_ #false]))
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(define (make-quad-attrs alist) (make-hasheq alist))
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(define (quad-attrs? x) (hash-eq? x))
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(define (quad-elems? x) (list? x))
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(define/contract (make-quad #:tag [tag #false]
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#:attrs [attrs (make-quad-attrs null)]
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#:elems [elems null])
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(() (#:tag quad-tag? #:attrs quad-attrs? #:elems quad-elems?) . ->* . quad?)
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(quad-constructor tag attrs elems))
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(define (quad-ref q key [default-val #false])
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(hash-ref (quad-attrs q) key default-val))
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(define (quad-set! q key val)
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(hash-set! (quad-attrs q) key val))
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(define-syntax (define-quad-field stx)
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(syntax-case stx ()
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[(_ FIELD)
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(with-syntax ([GETTER (format-id stx "quad-~a" #'FIELD)]
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[SETTER (format-id stx "set-quad-~a!" #'FIELD)])
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#'(begin
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(define (GETTER q) (quad-ref q 'FIELD))
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(define (SETTER q val) (quad-set! q 'FIELD val))))]))
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(define-quad-field posn)
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(define-quad-field char)
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(define (has-no-position? q) (not (has-position? q)))
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(define (has-position? q) (quad-posn q))
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(module+ test
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(define q (make-quad #:tag 'div #:attrs (make-hasheq '((hello . "world"))) #:elems (list "fine")))) |