▼scramble:   Assorted Utility Libraries
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slice
bytes-slice?
string-slice?
vector-slice?
print-slice-constructor-modes
slice-length
slice-contents
bytes-slice->string/  utf-8
string-slice->bytes/  utf-8
8.16.0.4
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15 Slices🔗ℹ

 (require scramble/slice) package: scramble-lib

struct

(struct slice (value start end))

  value : (or/c bytes? string? vector? slice?)
  start : exact-nonnegative-integer?
  end : exact-nonnegative-integer?
A slice represents a part of an underlying indexed collection (a byte string, string, or vector).

The start and end fields must be appropriate for value, and start must be less than or equal to end; otherwise, an exception is raised.

The slice constructor performs the following adjustments:

  • If end is #f, it is replaced with the length of the given value. That is slice-end never returns #f.

  • If value is a slice, then its value is extracted and start and end are adjusted to refer to the underlying value. That is, slice-value never returns a slice.

  • If start is equal to end, then value is replaced with the empty value of the same type, and start and end are set to 0.

See print-slice-constructor-modes for information about printing slices.

Note: Future versions of this library may extend the set of types allowed as values.

procedure

(bytes-slice? v) → boolean?

  v : any/c

procedure

(string-slice? v) → boolean?

  v : any/c

procedure

(vector-slice? v) → boolean?

  v : any/c
Returns #t if v is a slice containing a byte string, string, or vector, respectively; returns #f otherwise.

parameter

(print-slice-constructor-modes) → (listof (or/c #t #f 0 1))

(print-slice-constructor-modes modes) → void?
  modes : (listof (or/c #t #f 0 1))
 = '(0 1)
Determines whether a slice is printed as a struct or as its contents.

When a slices is printed using a mode (see gen:custom-write) in modes, it is printed as a struct; otherwise, only its contents are printed.

Examples:
> (define s (slice (for/vector ([i 16]) i) 9 13))
> (print s)

(slice '#(0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15) 9 13)

> (write s)

#(9 10 11 12)

> (parameterize ((print-slice-constructor-modes '(#t)))
    (write s))

#<slice: #(0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15) 9 13>

procedure

(slice-length s) → exact-nonnegative-integer?

  s : slice?
Returns the length of the slice.

Equivalent to (- (slice-end s) (slice-start s)).

procedure

(slice-contents s mutability) → (or/c bytes? string? vector?)

  s : slice?
  mutability : (or/c 'mutable 'immutable #f)
Returns a fresh copy of the slice’s contents.

If mutability is 'mutable, the result is mutable; if 'immutable, the result is immutable; otherwise, the result is immutable when the slice’s underlying value is immutable.

procedure

(bytes-slice->string/utf-8 bs [err-char]) → string?

  bs : bytes-slice?
  err-char : (or/c char? #f) = #f

procedure

(string-slice->bytes/utf-8 ss) → bytes?

  ss : string-slice?
Wrappers for bytes->string/utf-8 and string->bytes/utf-8, respectively, that obtain the value and indexes from the slice.

Example:
> (bytes-slice->string/utf-8 (slice #"hello world" 6 #f))

"world"

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