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342 lines
13 KiB
Racket
342 lines
13 KiB
Racket
#lang racket/base
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(require racket/contract net/url)
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(require (only-in racket/list empty? range splitf-at dropf dropf-right))
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(require (only-in racket/format ~a))
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(require (only-in racket/string string-join))
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(require (only-in racket/vector vector-member))
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(require (only-in racket/set set set->list set?))
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(module+ test (require rackunit))
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(require "debug.rkt")
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(provide (all-defined-out))
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;; general way of coercing to integer
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(define/contract (->int x)
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(any/c . -> . integer?)
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(cond
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[(integer? x) x]
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[(real? x) (floor x)]
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[(and (string? x) (> (len x) 0)) (->int (string->number x))]
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[(symbol? x) (->int (->string x))]
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[(char? x) (char->integer x)]
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[(has-length? x) (len x)]
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[else (error "Can't convert to integer:" x)]))
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;; general way of coercing to string
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(define/contract (->string x)
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(any/c . -> . string?)
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(cond
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[(string? x) x]
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[(empty? x) ""]
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[(symbol? x) (symbol->string x)]
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[(number? x) (number->string x)]
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[(url? x) (->string (->path x))]
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[(path? x) (path->string x)]
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[(char? x) (~a x)]
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[else (error (format "Can't make ~a into string" x))]))
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(module+ test
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(check-equal? (->string "foo") "foo")
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(check-equal? (->string '()) "")
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(check-equal? (->string 'foo) "foo")
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(check-equal? (->string 123) "123")
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(check-equal? (->string (string->url "foo/bar.html")) "foo/bar.html")
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(define file-name-as-text "foo.txt")
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(check-equal? (->string (string->path file-name-as-text)) file-name-as-text)
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(check-equal? (->string #\¶) "¶"))
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;; general way of coercing to symbol
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(define (->symbol thing)
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; todo: on bad input, it will pop a string error rather than symbol error
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(string->symbol (->string thing)))
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;; general way of coercing to path
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(define/contract (->path thing)
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(any/c . -> . path?)
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; todo: on bad input, it will pop a string error rather than path error
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(cond
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[(url? thing) (apply build-path (map path/param-path (url-path thing)))]
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[else (string->path (->string thing))]))
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(module+ test
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(check-equal? (->path "foo") (string->path "foo"))
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(check-equal? (->path 'foo) (string->path "foo"))
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(check-equal? (->path 123) (string->path "123"))
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(check-equal? (->path (string->url "foo/bar.html")) (string->path "foo/bar.html")))
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;; general way of coercing to url
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(define/contract (->url thing)
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(any/c . -> . url?)
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; todo: on bad input, it will pop a string error rather than url error
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(string->url (->string thing)))
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(define (->complete-path thing)
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(path->complete-path (->path thing)))
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;; general way of coercing to a list
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(define/contract (->list x)
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(any/c . -> . list?)
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(cond
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[(list? x) x]
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[(vector? x) (vector->list x)]
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[(set? x) (set->list x)]
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[else (list x)]))
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(module+ test
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(check-equal? (->list '(1 2 3)) '(1 2 3))
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(check-equal? (->list (list->vector '(1 2 3))) '(1 2 3))
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(check-equal? (->list (set 1 2 3)) '(3 2 1))
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(check-equal? (->list "foo") (list "foo")))
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;; general way of coercing to vector
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(define (->vector x)
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(any/c . -> . vector?)
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; todo: on bad input, it will pop a list error rather than vector error
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(cond
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[(vector? x) x]
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[else (list->vector (->list x))]))
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;; general way of coercing to boolean
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(define/contract (->boolean x)
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(any/c . -> . boolean?)
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;; in Racket, everything but #f is true
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(if x #t #f))
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(module+ test
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(check-true (->boolean #t))
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(check-false (->boolean #f))
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(check-true (->boolean "#f"))
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(check-true (->boolean "foo"))
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(check-true (->boolean '()))
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(check-true (->boolean '(1 2 3))))
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(define/contract (has-length? x)
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(any/c . -> . boolean?)
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(ormap (λ(proc) (proc x)) (list list? string? symbol? vector? hash? set?)))
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;; general way of asking for length
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(define/contract (len x)
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(has-length? . -> . integer?)
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(cond
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[(list? x) (length x)]
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[(string? x) (string-length x)]
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[(symbol? x) (len (->string x))]
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[(vector? x) (len (->list x))]
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[(hash? x) (len (hash-keys x))]
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[(set? x) (len (->list x))]
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[else #f]))
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(module+ test
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(check-equal? (len '(1 2 3)) 3)
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(check-not-equal? (len '(1 2)) 3) ; len 2
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(check-equal? (len "foo") 3)
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(check-not-equal? (len "fo") 3) ; len 2
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(check-equal? (len 'foo) 3)
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(check-not-equal? (len 'fo) 3) ; len 2
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(check-equal? (len (list->vector '(1 2 3))) 3)
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(check-not-equal? (len (list->vector '(1 2))) 3) ; len 2
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(check-equal? (len (set 1 2 3)) 3)
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(check-not-equal? (len (set 1 2)) 3) ; len 2
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(check-equal? (len (make-hash '((a . 1) (b . 2) (c . 3)))) 3)
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(check-not-equal? (len (make-hash '((a . 1) (b . 2)))) 3)) ; len 2
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(define/contract (sliceable-container? x)
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(any/c . -> . boolean?)
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(ormap (λ(proc) (proc x)) (list list? string? symbol? vector?)))
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(define/contract (gettable-container? x)
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(any/c . -> . boolean?)
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(ormap (λ(proc) (proc x)) (list sliceable-container? hash?)))
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;; general way of setting an item in a mutable container
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(define/contract (change x i value)
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((or/c vector? hash?) any/c any/c . -> . void?)
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; general-purpose mutable data object setter
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(cond
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[(vector? x) (vector-set! x i value)]
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[(hash? x) (hash-set! x i value)]
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[else (error "Can't set this datatype using change")]))
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;; general way of fetching an item from a container
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(define/contract (get container start [end #f])
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((gettable-container? any/c) ((λ(i)(or (integer? i) (and (symbol? i) (equal? i 'end)))))
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. ->* . any/c)
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(set! end
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(if (sliceable-container? container)
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(cond
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;; treat negative lengths as offset from end (Python style)
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[(and (integer? end) (< end 0)) (+ (len container) end)]
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;; 'end slices to the end
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[(equal? end 'end) (len container)]
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;; default to slice length of 1 (i.e, single-item retrieval)
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[(equal? end #f) (add1 start)]
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[else end])
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end))
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(define result (cond
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;; for sliceable containers, make a slice
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[(list? container) (for/list ([i (range start end)])
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(list-ref container i))]
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[(vector? container) (for/vector ([i (range start end)])
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(vector-ref container i))]
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[(string? container) (substring container start end)]
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[(symbol? container) (->symbol (get (->string container) start end))]
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;; for hash, just get item
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[(hash? container) (hash-ref container start)]
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[else #f]))
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;; don't return single-item results inside a list
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(if (and (sliceable-container? container) (= (len result) 1))
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(car (->list result))
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result))
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(module+ test
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(check-equal? (get '(0 1 2 3 4 5) 2) 2)
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(check-equal? (get `(0 1 ,(list 2) 3 4 5) 2) (list 2))
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(check-equal? (get '(0 1 2 3 4 5) 0 2) '(0 1))
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(check-equal? (get '(0 1 2 3 4 5) 2 -1) '(2 3 4))
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(check-equal? (get '(0 1 2 3 4 5) 2 'end) '(2 3 4 5))
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(check-equal? (get (list->vector '(0 1 2 3 4 5)) 2) 2)
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(check-equal? (get (list->vector'(0 1 2 3 4 5)) 0 2) (list->vector '(0 1)))
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(check-equal? (get (list->vector'(0 1 2 3 4 5)) 2 -1) (list->vector '(2 3 4)))
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(check-equal? (get (list->vector'(0 1 2 3 4 5)) 2 'end) (list->vector '(2 3 4 5)))
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(check-equal? (get "purple" 2) "r")
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(check-equal? (get "purple" 0 2) "pu")
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(check-equal? (get "purple" 2 -1) "rpl")
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(check-equal? (get "purple" 2 'end) "rple")
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(check-equal? (get 'purple 2) 'r)
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(check-equal? (get 'purple 0 2) 'pu)
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(check-equal? (get 'purple 2 -1) 'rpl)
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(check-equal? (get 'purple 2 'end) 'rple)
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(check-equal? (get (make-hash `((a . ,(list 1)) (b . ,(list 2)) (c . ,(list 3)))) 'a) (list 1)))
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;; general way of testing for membership (à la Python 'in')
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;; put item as first arg so function can use infix notation
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;; (item . in . container)
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(define/contract (in? item container)
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(any/c any/c . -> . boolean?)
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(->boolean (cond
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[(list? container) (member item container)] ; returns #f or sublist beginning with item
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[(vector? container) (vector-member item container)] ; returns #f or zero-based item index
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[(hash? container)
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(and (hash-has-key? container item) (get container item))] ; returns #f or hash value
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[(string? container) ((->string item) . in? . (map ->string (string->list container)))] ; returns #f or substring beginning with item
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[(symbol? container) ((->string item) . in? . (->string container))] ; returns #f or subsymbol (?!) beginning with item
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[else #f])))
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(module+ test
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(check-true (2 . in? . '(1 2 3)))
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(check-false (4 . in? . '(1 2 3)))
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(check-true (2 . in? . (list->vector '(1 2 3))))
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(check-false (4 . in? . (list->vector '(1 2 3))))
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(check-true ('a . in? . (make-hash '((a . 1) (b . 2) (c . 3)))))
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(check-false ('x . in? . (make-hash '((a . 1) (b . 2) (c . 3)))))
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(check-true ("o" . in? . "foobar"))
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(check-false ("z" . in? . "foobar"))
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(check-true ('o . in? . 'foobar))
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(check-false ('z . in? . 'foobar))
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(check-false ("F" . in? . #\F)))
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;; stringish: data type that can be trivially converted to string
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;; todo: merge this with pathish
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(define/contract (stringish? x)
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(any/c . -> . boolean?)
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(with-handlers ([exn:fail? (λ(e) #f)])
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(->boolean (->string x))))
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;; python-style string testers
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(define/contract (starts-with? str starter)
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(stringish? stringish? . -> . boolean?)
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(let ([str (->string str)]
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[starter (->string starter)])
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(and (<= (len starter) (len str)) (equal? (get str 0 (len starter)) starter))))
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(module+ test
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(check-true ("foobar" . starts-with? . "foo"))
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(check-true ("foobar" . starts-with? . "f"))
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(check-true ("foobar" . starts-with? . "foobar"))
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(check-false ("foobar" . starts-with? . "bar")))
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(define/contract (ends-with? str ender)
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(string? string? . -> . boolean?)
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(and (<= (len ender) (len str)) (equal? (get str (- (len str) (len ender)) 'end) ender)))
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(module+ test
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(check-true ("foobar" . ends-with? . "bar"))
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(check-true ("foobar" . ends-with? . "r"))
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(check-true ("foobar" . ends-with? . "foobar"))
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(check-false ("foobar" . ends-with? . "foo")))
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;; trim from beginning & end of list
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(define (trim items test-proc)
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(list? procedure? . -> . list?)
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(dropf-right (dropf items test-proc) test-proc))
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(module+ test
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; (check-equal? (trim (list "\n" " " 1 2 3 "\n") whitespace?) '(1 2 3))
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(check-equal? (trim (list 1 3 2 4 5 6 8 9 13) odd?) '(2 4 5 6 8)))
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;; split list into list of sublists using test-proc
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(define/contract (splitf-at* xs split-test)
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;; todo: better error message when split-test is not a predicate
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(list? predicate/c . -> . (listof list?))
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(define (&splitf-at* xs [acc '()]) ; use acc for tail recursion
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(if (empty? xs)
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;; reverse because accumulation is happening backward
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;; (because I'm using cons to push latest match onto front of list)
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(reverse acc)
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(let-values ([(item rest)
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;; drop matching elements from front
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;; then split on nonmatching
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;; = nonmatching item + other elements (which will start with matching)
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(splitf-at (dropf xs split-test) (compose1 not split-test))])
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;; recurse, and store new item in accumulator
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(&splitf-at* rest (cons item acc)))))
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;; trim off elements matching split-test
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(&splitf-at* (trim xs split-test)))
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(module+ test
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; (check-equal? (splitf-at* '("foo" " " "bar" "\n" "\n" "ino") whitespace?) '(("foo")("bar")("ino")))
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(check-equal? (splitf-at* '(1 2 3 4 5 6) even?) '((1)(3)(5))))
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;; convert a bytecount into a string
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(define/contract (bytecount->string bytecount)
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(integer? . -> . string?)
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(define (format-with-threshold threshold suffix)
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;; upconvert by factor of 100 to get two digits after decimal
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(format "~a ~a" (exact->inexact (/ (round ((* bytecount 100) . / . threshold)) 100)) suffix))
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(define threshold-kilobyte 1000)
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(define threshold-megabyte (threshold-kilobyte . * . threshold-kilobyte))
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(define threshold-gigabyte (threshold-megabyte . * . threshold-kilobyte))
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(define threshold-terabyte (threshold-gigabyte . * . threshold-kilobyte))
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(cond
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[(bytecount . >= . threshold-terabyte) (format-with-threshold threshold-terabyte "TB")]
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[(bytecount . >= . threshold-gigabyte) (format-with-threshold threshold-gigabyte "GB")]
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[(bytecount . >= . threshold-megabyte) (format-with-threshold threshold-megabyte "MB")]
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[(bytecount . >= . threshold-kilobyte) (format-with-threshold threshold-kilobyte "KB")]
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[else (format "~a bytes" bytecount)]))
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;; for use inside quasiquote
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;; instead of ,(when ...) use ,@(when/splice ...)
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;; to avoid voids
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(define-syntax-rule (when/splice test body) (if test (list body) '()))
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