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typesetting/quad/quadwriter/query.rkt

82 lines
3.2 KiB
Racket

#lang debug racket
(require quad/base "struct.rkt" "param.rkt")
(provide (all-defined-out))
(define (make-linear-index q)
(cons q (append* (for/list ([elem (in-list (quad-elems q))]
#:when (quad? elem))
(make-linear-index elem)))))
(define (string->key str #:this [this? #false])
(match str
["doc" 'doc]
[(or "section" "sec" "s") 'section]
[(or "page" "pg" "p") 'page]
[(or "column" "col" "c") 'column]
[(or "block" "b") 'block]
[(or "line" "ln" "l") 'line]))
(define preds (hasheq 'doc doc-quad?
'section section-quad?
'page page-quad?
'column column-quad?
'block block-quad?
'line line-quad?))
(define quad-params (hasheq 'doc current-doc
'section current-section
'page current-page
'column current-column
'block current-block
'line current-line))
(define (parse-query str)
(for/list ([piece (in-list (string-split str ":"))])
(match (regexp-match #px"^(.*)\\[(.*?)\\]$" piece)
[#false (cons (string->key piece) #false)]
[(list _ name "this") (cons (let ([quad-param-val ((hash-ref quad-params (string->key name)))])
(λ (q) (eq? q quad-param-val))) 1)]
[(list _ name arg) (cons (hash-ref preds (string->key name)) (or (string->number arg)
(string->symbol arg)))])))
(define (query quad-or-index query-str)
(for/fold ([qs (match quad-or-index
[(? quad? q) (make-linear-index q)]
[idx idx])]
#:result (and qs (car qs)))
([query-piece (in-list (parse-query query-str))])
(match-define (cons pred count) query-piece)
(let loop ([qs qs][seen 0])
(define maybe-tail (memf pred qs))
(and maybe-tail
(let ([seen (add1 seen)])
(cond
[(= seen count) maybe-tail]
[else (loop (cdr maybe-tail) seen)]))))))
(module+ test
(require rackunit)
(define counter 0)
(define-syntax-rule (factory type proc)
(make-quad #:type type
#:elems (for/list ([i (in-range 3)])
(set! counter (add1 counter))
(define new-q (proc))
(quad-update! new-q
[tag (format "~a[~a]-~a" 'proc counter (gensym))])
(hash-set! (quad-attrs new-q) 'count counter)
new-q)))
(define (line) (make-quad #:type line-quad))
(define (block) (factory block-quad line))
(define (col) (factory column-quad block))
(define (page) (factory page-quad col))
(define (sec) (factory section-quad page))
(define (count q) (quad-ref q 'count))
(define doc (factory doc-quad sec))
(check-equal? (count (query doc "sec[2]")) 242)
(check-equal? (count (query doc "sec[2]:pg[1]")) 162)
(check-equal? (count (query doc "sec[2]:pg[1]:ln[3]")) 128))