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typesetting/quad/quadwriter/query.rkt

51 lines
1.7 KiB
Racket

#lang debug racket
(require quad/base "struct.rkt")
(verbose-quad-printing? #t)
(define-syntax-rule (factory type proc)
(make-quad #:type type
#:elems (for/list ([i (in-range 2)])
(quad-update! (proc)
[tag (format "~a[~a]" 'proc (add1 i))]))))
(define (line) (make-quad #:type line-quad))
(define (block) (factory block-quad line))
(define (col) (factory column-quad block))
(define (sec) (factory section-quad col))
(define doc (factory doc-quad sec))
(define (parse-query-str str)
(define (string->pred str)
(match str
["doc" doc-quad?]
["section" section-quad?]
["page" page-quad?]
["column" column-quad?]
["block" block-quad?]
["line" line-quad?]))
(for/list ([piece (in-list (string-split str ":"))])
(match (regexp-match #px"^(.*)\\[(.*?)\\]$" piece)
[#false (cons (string->pred piece) #false)]
[(list all name arg) (cons (string->pred name) (or (string->number arg)
(string->symbol arg)))])))
(define (query q query-str)
(define query-assocs (parse-query-str query-str))
#R query-assocs
(for/fold ([ctx q]
#:result #R ctx)
([(pred count) (in-dict query-assocs)])
#R pred
(define matches null)
(let loop ([this ctx])
#R this
(cond
[(= (length matches) count) #R (car matches)]
[(quad? this)
(when (pred this)
(set! matches (cons this matches)))
(for-each loop (quad-elems this))]
[else this]))))
(query doc "section[1]:line[2]")