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86 lines
3.4 KiB
Racket
86 lines
3.4 KiB
Racket
#lang debug racket
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(require quad/base "struct.rkt" "param.rkt")
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(provide (all-defined-out))
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;; we want to construct a query index once with reversed variant
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;; so we don't have to keep generating it
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(struct query-index (forward reverse) #:transparent)
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(define (make-query-index q)
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(define qs (let loop ([q q])
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(cons q (append* (for/list ([elem (in-list (quad-elems q))]
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#:when (quad? elem))
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(loop elem))))))
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(query-index qs (reverse qs)))
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(define (string->key str #:this [this? #false])
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(match str
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["doc" 'doc]
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[(or "section" "sec" "s") 'section]
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[(or "page" "pg" "p") 'page]
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[(or "column" "col" "c") 'column]
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[(or "block" "b") 'block]
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[(or "line" "ln" "l") 'line]))
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(define preds (hasheq 'doc doc-quad?
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'section section-quad?
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'page page-quad?
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'column column-quad?
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'block block-quad?
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'line line-quad?))
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(define (parse-query str)
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(for/list ([piece (in-list (string-split str ":"))])
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(match (regexp-match #px"^(.*)\\[(.*?)\\]$" piece)
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[#false (cons (string->key piece) #false)]
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[(list _ name arg) (cons (hash-ref preds (string->key name)) (or (string->number arg)
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(string->symbol arg)))])))
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(define (query quad-or-index query-str [querying-q #false])
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(define qi (match quad-or-index
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[(? quad? q) (make-query-index q)]
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[idx idx]))
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(for/fold ([qs (query-index-forward qi)]
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#:result (and qs (car qs)))
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([query-piece (in-list (parse-query query-str))])
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(match query-piece
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[(cons pred 'this)
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;; resolve `this` by finding the querying quad, and searching backward
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(define this-thing (findf pred (memq querying-q (query-index-reverse qi))))
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;; once we have this-thing, locate it in the forward index and keep going
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(memq this-thing (query-index-forward qi))]
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[(cons pred count)
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(let loop ([qs qs][seen 0])
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(define maybe-tail (memf pred qs))
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(and maybe-tail
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(let ([seen (add1 seen)])
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(cond
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[(= seen count) maybe-tail]
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[else (loop (cdr maybe-tail) seen)]))))])))
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(module+ test
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(require rackunit)
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(define counter 0)
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(define-syntax-rule (factory type proc)
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(make-quad #:type type
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#:elems (for/list ([i (in-range 3)])
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(set! counter (add1 counter))
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(define new-q (proc))
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(quad-update! new-q
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[tag (format "~a[~a]-~a" 'proc counter (gensym))])
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(hash-set! (quad-attrs new-q) 'count counter)
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new-q)))
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(define (line) (make-quad #:type line-quad))
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(define (block) (factory block-quad line))
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(define (col) (factory column-quad block))
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(define (page) (factory page-quad col))
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(define (sec) (factory section-quad page))
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(define (count q) (quad-ref q 'count))
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(define doc (factory doc-quad sec))
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(check-equal? (count (query doc "sec[2]")) 242)
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(check-equal? (count (query doc "sec[2]:pg[1]")) 162)
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(check-equal? (count (query doc "sec[2]:pg[1]:ln[3]")) 128)) |