Contiguous non-owning view of items of the same schema.

Span

Methods

assign

(other --) Replaces the current view with the view described by other.

Postconditions

  • Data and size match other.

at

(key -- ref) Returns Ref to the item at key.

Preconditions

  • key in [0..current item count - 1].

data

(-- ref) Returns the stored Ref to the first item.

Postconditions

  • Result can be NIL if the item count is 0.

iter

(-- iter) Returns a forward iteration source over the current items.

Postconditions

  • The iteration range matches span.

iterReverse

(-- iter) Returns a reverse iteration source over the current items.

Postconditions

  • The iteration starts at the last item and proceeds backward.

next

(-- item valid) Returns the current item and advances the view by one item when valid.

Postconditions

  • valid is TRUE when an item was available.
  • When valid is TRUE, the item count decreases by one for the remaining view.

size

(-- count) Returns the current item count.

slice

(offset size -- theSpan) Returns a span over the selected subrange.

Preconditions

  • offset in [0..current item count].
  • size (the argument) in [0..current item count - offset].

Examples

"Span"    use
"control" use

{} () {} [
  span: (10 20 30 40) toSpan;
  part: 1 2 @span.slice;
  part.size printStack _:;
  0 @part.at printStack _:;
  1 @part.at printStack _:;
] "main" exportFunction

Expected Output During Compilation

2
Int32 Ref
Int32 Ref

span

(-- theSpan) Returns a span over the same range.

spanStatic

(-- theSpan) Returns a static span view over the same range.

stringView

(-- theStringView) Returns StringView built from the same data and size.

Runtime example: reverse iteration

"Span"    use
"String"  use
"control" use

{} Int32 {} [
  span: (10 20 30) toSpan;
  it: @span.iterReverse;
  item0: ok0: @it.next;;
  item1: ok1: @it.next;;
  item2: ok2: @it.next;;
  item3: ok3: @it.next;;
  ("ok0=" ok0 LF
    "v0=" item0 new LF
    "ok1=" ok1 LF
    "v1=" item1 new LF
    "ok2=" ok2 LF
    "v2=" item2 new LF
    "ok3=" ok3 LF) printList
  0
] "main" exportFunction

Expected Output

ok0=TRUE
v0=30
ok1=TRUE
v1=20
ok2=TRUE
v2=10
ok3=FALSE

toSpan (source -- theSpan)

Converts supported sources to Span.

Runtime example

"Span"    use
"String"  use
"control" use

{} Int32 {} [
  numbers: (10 20 30) toSpan;
  ("size=" numbers.size LF
    "first=" 0 @numbers.at new LF
    "last=" 2 @numbers.at new LF) printList
  0
] "main" exportFunction

Expected Output

size=3
first=10
last=30

toSpan2 (spanData spanSize -- theSpan)

Constructs Span directly from item data and item count.

Examples

"Span"    use
"control" use

{} () {} [
  span: (10 20 30) toSpan;
  part: @span.data 2 toSpan2;
  part.size printStack _:;
  0 @part.at printStack _:;
  1 @part.at printStack _:;
] "main" exportFunction

Expected Output During Compilation

2
Int32 Ref
Int32 Ref

Runtime example

"Span"    use
"String"  use
"control" use

{} Int32 {} [
  span: (10 20 30 40) toSpan;
  part: @span.data 2 toSpan2;
  ("size=" part.size LF
    "first=" 0 @part.at new LF
    "second=" 1 @part.at new LF) printList
  0
] "main" exportFunction

Expected Output

size=2
first=10
second=20

See also