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typesetting/quad/utils.rkt

266 lines
12 KiB
Racket

10 years ago
#lang racket/base
(require sugar/list sugar/define)
(require (for-syntax racket/syntax racket/base) racket/string racket/contract racket/list sugar/debug racket/bool hyphenate racket/function math/flonum)
(require "quads.rkt" "world.rkt" "measure.rkt")
;; predicate for use below
(define (list-of-mergeable-attrs? xs)
(and (list? xs) (andmap (λ(x) (or (quad? x) (quad-attrs? x) (hashable-list? x))) xs)))
;; faster than (listof pair?)
(define (pairs? x) (and (list? x) (andmap pair? x)))
;; push together multiple attr sources into one list of pairs.
;; mostly a helper function for the two attr functions below.
(define+provide/contract (join-attrs quads-or-attrs-or-lists)
(list-of-mergeable-attrs? . -> . pairs?)
(append-map hash->list (filter-not false? (map (λ(x)
(cond
[(quad? x) (quad-attrs x)]
[(quad-attrs? x) x]
[(hashable-list? x) (apply hash x)]
[else #f])) quads-or-attrs-or-lists))))
;; merge concatenates attributes, with later ones overriding earlier.
;; most of the work is done by join-attrs.
(define+provide/contract (merge-attrs . quads-or-attrs-or-lists)
(() #:rest list-of-mergeable-attrs? . ->* . quad-attrs?)
(define all-attrs (join-attrs quads-or-attrs-or-lists))
(apply hash (flatten all-attrs)))
;; functionally update a quad attr. Similar to hash-set
(define+provide/contract (quad-attr-set q k v)
(quad? symbol? any/c . -> . quad?)
(quad (quad-name q) (merge-attrs (quad-attrs q) (list k v)) (quad-list q)))
;; functionally update multiple quad attrs. Similar to hash-set*
(define+provide/contract (quad-attr-set* q . kvs)
((quad?) #:rest hashable-list? . ->* . quad?)
(for/fold ([current-q q])([kv-list (in-list (slice-at kvs 2))])
(apply quad-attr-set current-q kv-list)))
;; functionally remove a quad attr. Similar to hash-remove
(define+provide/contract (quad-attr-remove q k)
(quad? symbol? . -> . quad?)
(if (quad-attrs q)
(quad (quad-name q) (hash-remove (quad-attrs q) k) (quad-list q))
q))
;; functionally remove multiple quad attrs. Similar to hash-remove
(define+provide/contract (quad-attr-remove* q . ks)
((quad?) #:rest (λ(ks) (and (list? ks) (andmap symbol? ks))) . ->* . quad?)
(for/fold ([current-q q])([k (in-list ks)])
(quad-attr-remove current-q k)))
(define+provide/contract (quad-map proc q)
(procedure? quad? . -> . quad?)
(quad (quad-name q) (quad-attrs q) (map proc (quad-list q))))
;; flatten merges attributes, but applies special logic suitable to flattening
;; for instance, resolving x and y coordinates.
(define+provide/contract (flatten-attrs . quads-or-attrs-or-falses)
(() #:rest (listof (or/c quad? quad-attrs?)) . ->* . quad-attrs?)
(define all-attrs (join-attrs quads-or-attrs-or-falses))
(define-values (x-attrs y-attrs other-attrs-reversed)
(for/fold ([xas null][yas null][oas null])([attr (in-list all-attrs)])
(cond
[(equal? (car attr) world:x-position-key) (values (cons attr xas) yas oas)]
[(equal? (car attr) world:y-position-key) (values xas (cons attr yas) oas)]
[else (values xas yas (cons attr oas))])))
(define (make-cartesian-attr key attrs) (if (empty? attrs) empty (cons key (apply + (map cdr attrs)))))
(define-values (x-attr y-attr) (apply values (map make-cartesian-attr (list world:x-position-key world:y-position-key) (list x-attrs y-attrs))))
(apply hash (flatten (list* x-attr y-attr (reverse other-attrs-reversed)))))
;; pushes attributes down from parent quads to children,
;; resulting in a flat list of quads.
;; input is often large, so macro allows us to avoid allocation
(provide flatten-quad)
(define-syntax-rule (flatten-quad q)
; (quad? . -> . quads?)
(flatten
(let loop ([x q][parent #f])
(cond
[(quad? x)
(let ([x-with-parent-attrs (quad (quad-name x)
(flatten-attrs parent x) ; child positioned last so it overrides parent attributes
(quad-list x))])
(if (empty? (quad-list x))
x-with-parent-attrs ; no subelements, so stop here
(map (λ(xi) (loop xi x-with-parent-attrs)) (quad-list x))))] ; replace quad with its elements
[(string? x) (quad (quad-name parent) (quad-attrs parent) (list x))]))))
;; flatten quad as above,
;; then dissolve it into individual character quads while copying attributes
;; input is often large, so macro allows us to avoid allocation
(provide split-quad)
(define-syntax-rule (split-quad q)
;(quad? . -> . quads?)
(letrec ([do-explode (λ(x [parent #f])
(cond
[(quad? x)
(if (empty? (quad-list x))
x ; no subelements, so stop here
(map (λ(xi) (do-explode xi x)) (quad-list x)))] ; replace quad with its elements, exploded
[(string? x) (map (λ(xc) (quad 'word (quad-attrs parent) (list xc))) (regexp-match* #px"." x))]))])
(flatten (map do-explode (flatten-quad q)))))
;; merge chars into words (and boxes), leave the rest
;; if two quads are mergeable types, and have the same attributes,
;; they get merged.
;; input is often large, so macro allows us to avoid allocation
(provide join-quads)
(define-syntax-rule (join-quads qs-in)
;((quads?)(quads?) . ->* . quads?)
(let ([make-matcher (λ (base-q)
(λ(q)
(and (member (quad-name q) world:mergeable-quad-types)
(not (whitespace/nbsp? q))
;; if key doesn't exist, it is compared against the default value.
;; this way, a nonexistent value will test true against a default value.
(andmap (λ(key default) (equal? (quad-attr-ref base-q key default) (quad-attr-ref q key default)))
(list world:font-name-key
world:font-size-key
world:font-weight-key
world:font-style-key)
(list (world:font-name-default)
(world:font-size-default)
(world:font-weight-default)
(world:font-style-default))))))])
(let loop ([qs qs-in][acc null])
(if (null? qs)
(reverse acc)
(let* ([base-q (first qs)]
[mergeable-and-matches-base? (make-matcher base-q)]) ; make a new predicate function for this quad
(cond
[(mergeable-and-matches-base? base-q)
;; take as many quads that match, using the predicate function
(define-values (matching-qs other-qs) (splitf-at (cdr qs) mergeable-and-matches-base?))
(define new-word (word (quad-attrs base-q) (string-append* (append-map quad-list (cons base-q matching-qs)))))
(loop other-qs (cons new-word acc))]
;; otherwise move on to the next in line
[else (loop (cdr qs) (cons base-q acc))]))))))
;; the last char of a quad
(define+provide/contract (quad-last-char q)
(quad? . -> . (or/c #f string?))
(define split-qs (split-quad q)) ; split makes it simple, but is it too expensive?
(if (or (empty? split-qs) (empty? (quad-list (last split-qs))))
#f
(car (quad-list (last split-qs)))))
;; the first char of a quad
(define+provide/contract (quad-first-char q)
(quad? . -> . (or/c #f string?))
(define split-qs (split-quad q)) ; explosion makes it simple, but is it too expensive?
(if (or (empty? split-qs) (empty? (quad-list (first split-qs))))
#f
(car (quad-list (first split-qs)))))
;; propagate x and y adjustments throughout the tree,
;; using parent x and y to adjust children, and so on.
(define+provide/contract (compute-absolute-positions i [parent-x 0][parent-y 0])
((quad?) (integer? integer?) . ->* . quad?)
(cond
[(quad? i)
(define adjusted-x (round-float (+ (quad-attr-ref i world:x-position-key 0) parent-x)))
(define adjusted-y (round-float (+ (quad-attr-ref i world:y-position-key 0) parent-y)))
(quad (quad-name i) (merge-attrs i (list world:x-position-key adjusted-x world:y-position-key adjusted-y)) (map (λ(ii) (compute-absolute-positions ii adjusted-x adjusted-y)) (quad-list i)))]
[else i]))
;; simple assert. should get moved to sugar/debug
(provide assert)
(define-syntax-rule (assert pred expr)
(let ([result expr])
(if (pred result)
result
(error 'assert-failure (format "\n~a\nevaluates to:\n~a\nwhich is not:\n~a" 'expr result 'pred)))))
;; peeks at arguments and times execution
(provide snoop)
(define-syntax (snoop stx)
(syntax-case stx ()
[(_ proc arg ... . rest)
(with-syntax ()
#'(begin
(displayln (format "Evaluating ~s" '(proc arg ... . rest)))
(let ([start (current-milliseconds)]
[result (proc arg ... . rest)]
[end (current-milliseconds)])
(displayln (format "Evaluation of ~s took ~a ms\nResult ~a" '(proc arg ... . rest) (- end start) result))
result)))]))
;; find total pages in doc by searching on page count key.
(define+provide/contract (pages-in-doc doc)
(doc? . -> . integer?)
(add1 (apply max (map (curryr quad-attr-ref world:page-key 0) (quad-list doc)))))
;; todo: how to guarantee line has leading key?
(define+provide/contract (compute-line-height line)
(line? . -> . line?)
(quad-attr-set line world:height-key (quad-attr-ref/parameter line world:leading-key)))
(define (fixed-height? q) (quad-has-attr? q world:height-key))
(define+provide/contract (quad-height q)
(quad? . -> . number?)
(quad-attr-ref q world:height-key 0))
;; use heights to compute vertical positions
(define+provide/contract (add-vert-positions starting-quad)
(quad? . -> . quad?)
(define-values (new-quads final-height)
(for/fold ([new-quads empty][height-so-far 0])([q (in-list (quad-list starting-quad))])
(values (cons (quad-attr-set q world:y-position-key height-so-far) new-quads)
(round-float (+ height-so-far (quad-height q))))))
(quad (quad-name starting-quad) (quad-attrs starting-quad) (reverse new-quads)))
;; recursively hyphenate strings in a quad
(define+provide/contract (hyphenate-quad x)
(quad? . -> . quad?)
(cond
[(quad? x) (quad-map hyphenate-quad x)]
[(string? x) (hyphenate x
#:min-length 6
#:min-left-length 3
#:min-right-length 3)]
[else x]))
;; just because it comes up a lot
(provide split-last)
(define-syntax-rule (split-last xs)
(let-values ([(first-list last-list) (split-at-right xs 1)])
(values first-list (car last-list))))
;; like cons, but joins a list to an atom
(provide snoc)
(define-syntax-rule (snoc xs x)
(append xs (list x)))
;; folded flonum operators
;; (for use with multiple args, standard flonum ops have arity = 2)
(define-syntax (define-folded-op stx)
(syntax-case stx ()
[(_ op starting-val)
(with-syntax ([fold-op (format-id stx "fold-~a" #'op)]
[ops (format-id stx "~as" #'op)])
#'(begin
(provide fold-op ops)
(define-syntax-rule (ops x (... ...))
(fold-op (list x (... ...))))
(define-syntax-rule (fold-op xs)
(foldl op starting-val xs))))]))
(define-folded-op fl+ 0.0)
(define-folded-op fl- 0.0)
(define-folded-op fl* 1.0)
(define-folded-op fl/ 1.0)