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Set expressions¤

Overview¤

The set store unique items, without any particular order. Items in the set must be of the same type. The set is one of basic data structures provided by SP-Lang.

A set is best suited for a testing value for membership rather than retrieving a specific element from a set.

  • !SET: Set of items.
  • !IN: Membership test.

!SET¤

Set of items.

Type: Implicit sequence, Mapping.

Synopsis:

!SET
- ...
- ...

Hint

Use !COUNT to determine number of items in the set.

There are several ways, how a set can be specified in SP-Lang:

Example

!SET
- "One"
- "Two"
- "Three"
- "Four"
- "Five"

Unordered set

YAML unordered set:

!!set
? Yellow pork
? Pink grass
? White snow

YAML flow sequences

Concise set using YAML flow sequences:

!SET ["One", "Two", "Three", "Four", "Five"]

Example

The mapping form:

!SET
with:
- "One"
- "Two"
- "Three"
- "Four"
- "Five"

!IN¤

Membership test.

Type: Mapping.

!IN
what: <...>
where: <...>

The !IN expression is used to check if a value what exists in a value where or not. Value where is a string, container (list, set, dictionary), structural type etc. Evaluate to true if it finds a value what in the specified value where and false otherwise.

The !IN expression is described for the individual container types in the following chapters:

Example

!IN
what: 5
where:
  - 1
  - 2
  - 3
  - 4
  - 5

Check for a presence of the value 5 in the list where. Returns true.

Example

!IN
what: "Willy"
where: "John Willy Boo"

Check for a presence of the substring "Willy" in the John Willy Boo value. Returns true.

Example

!IN
what: 3
where:
  !SET
  with:
    - 1
    - 2
    - 5
    - 8

Check for a presence of the value 3 in the set where. Returns false.