Contiguous non-owning view of items of the same schema with a schema-level fixed size.

The item count is a static field of the schema (schemaName gives SpanStatic<Int32, 3>): it is known at compile time, spans of different sizes have different schemas, and slice and toSpanStatic2 need a known size. Unlike Span, the view cannot change its size.

The range checks of at and slice and the size check of assign are assertions: a check that is provably false at compile time fails compilation (also with -ndebug); an unknown check runs while DEBUG is on (the default) and terminates the program with its message (Key is out of bounds, Offset is out of bounds, Size is out of bounds, Inconsistent sizes) and exit status 2, and is omitted with -ndebug. The known-size and item-schema requirements are compile-time requirements.

SpanStatic

Methods

assign

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

Preconditions

  • other.size equals the current static size.

Postconditions

  • The span refers to other's storage afterwards (its data is other.data); no items are copied.
  • The static size is unchanged.

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.

iter

(-- iter) Returns the dynamic Span over the current items that span returns; iterate it with Span's next.

iterReverse

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

Postconditions

  • The iteration starts at the last item and proceeds backward.
  • The result is an iterator Dict with the method next (-- item valid): item is a Ref to the current item (the item is mutable only when the span's stored reference is mutable and iterReverse was called through a mutable view of the span; next itself needs a mutable view of the iterator), valid is TRUE when an item was available; when it is TRUE, the iterator moves one item towards the first item.

size

(-- count) Returns the current item count.

slice

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

Preconditions

  • offset in [0..current item count].
  • size (the argument) in [0..current item count - offset].
  • size is known at compile time: it becomes part of the result's schema (offset may be unknown).

Examples

"SpanStatic" use
"control"    use

{} () {} [
  span: (10 20 30 40) toSpanStatic;
  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 dynamic Span over the same range.

spanStatic

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

stringView

(-- theStringView) Requires Nat8 items and an Int32 count. Returns an immutable StringView over the same bytes and size; it does not format arbitrary items as text.

Runtime example: reverse iteration

"SpanStatic" use
"String"     use
"control"    use

{} Int32 {} [
  span: (10 20 30) toSpanStatic;
  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

toSpanStatic (source -- theSpan)

Converts supported sources to SpanStatic.

Runtime example

"SpanStatic" use
"String"     use
"control"    use

{} Int32 {} [
  numbers: (10 20 30) toSpanStatic;
  ("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

toSpanStatic2 (spanData spanSize -- theSpan)

Constructs SpanStatic directly from item data and item count.

Examples

"SpanStatic" use
"control"    use

{} () {} [
  span: (10 20 30) toSpanStatic;
  part: @span.data 2 toSpanStatic2;
  part.size printStack _:;
  0 @part.at printStack _:;
  1 @part.at printStack _:;
] "main" exportFunction

Expected Output During Compilation

2
Int32 Ref
Int32 Ref

Runtime example

"SpanStatic" use
"String"     use
"control"    use

{} Int32 {} [
  span: (10 20 30 40) toSpanStatic;
  part: 1 @span.at 2 toSpanStatic2;
  ("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=20
second=30

See also