This topic describes the syntax and parameters of list functions. This topic also provides examples on how to use the functions.

Functions

Function Description
lst_make Constructs a list.
lst_insert Inserts elements to a specified position in a list.
lst_append Adds elements to the end of a list.
lst_delete_at Deletes the element at a specified position from a list.
lst_reverse Reverses the order of elements in a list.
op_slice Obtains elements at specified positions from a list.
lst_get Obtains an element from a list or a tuple.
op_len Calculates the number of elements in a list or a tuple.

lst_make

  • Syntax
    lst_make(Value 1, Value 2, ...)
  • Parameters
    Parameter Type Required Description
    Value 1 Arbitrary Yes The element in the list that you want to construct.
    Value 2 Arbitrary Yes The element in the list that you want to construct.
  • Response

    The constructed list is returned.

  • Example
    Transformation rule:
    e_set("hello", lst_make("k1","k2"))
    Result:
    hello: ["k1","k2"]

lst_insert

  • Syntax
    lst_insert(List, Position, Value 1, Value 2, ...)
  • Parameters
    Parameter Type Required Description
    List List Yes The list to which you want to insert elements.
    Position Number Yes The position at which you want to insert the elements.
    Value 1 Arbitrary Yes The element that you want to insert.
    Value 2 Arbitrary No The element that you want to insert.
  • Response

    The updated list is returned.

  • Example
    Raw log entry:
    ctx: ["k1","k2"]
    Transformation rule:
    e_set("hello", lst_insert(v("ctx"), 0, "k0"))
    Result:
    ctx: ["k1","k2"]
    hello: ["k0", "k1", "k2"]

lst_append

  • Syntax
    lst_append(List, Value 1, Value 2, ...)
  • Parameters
    Parameter Type Required Description
    List List Yes The list to which you want to append elements.
    Value 1 Arbitrary Yes The element that you want to append.
    Value 2 Arbitrary No The element that you want to append.
  • Response

    The updated list is returned.

  • Example
    Raw log entry:
    ctx: ["k1","k2"]
    Transformation rule:
    e_set("hello", lst_append(v(ctx), "k3"))
    Result:
    ctx: ["k1","k2"]
    hello: ["k1", "k2", "k3"]

lst_delete_at

  • Syntax
    lst_delete_at(List, Position)
  • Parameters
    Parameter Type Required Description
    List list Yes The list from which you want to delete an element.
    Position Number Yes The position of the element that you want to delete. The position of the first element is 0.
  • Response

    The updated list is returned.

  • Example
    Raw log entry:
    ctx: ["k1","k2"]
    Transformation rule:
    e_set("hello", lst_delete_at(v("ctx"),1))
    Result:
    ctx: ["k1","k2"]
    hello: ["k1"]

lst_reverse

  • Syntax
    lst_reverse(List)
  • Parameters
    Parameter Type Required Description
    List List Yes The list in which you want to reverse the order of elements.
  • Response

    The updated list is returned.

  • Example
    Raw log entry:
    ctx: ["v1","v2"]
    Transformation rule:
    e_set("hello", lst_reverse(v("ctx")))
    Result:
    ctx: ["v1","v2"]
    hello: ["v2","v1"]

lst_get

The lst_get function is used to obtain an element from a list or a tuple.

  • Syntax
    lst_get (List, Element index)
  • Parameters
    Parameter Type Required Description
    List List Yes The list from which you want to obtain an element.
    Element index Int Yes The index of the first element is 0. For example, the ["a","b","c"] list includes the elements a, b, and c. In this case, the corresponding element indexes are 0, 1, and 2.
  • Response

    An element is returned.

  • Example
    """
    Raw log entry:
      ctx: ["v1","v2"]
    Result:
      ctx: ["v1","v2"]
      hello: "v2"
    """
    e_set("hello", lst_get(v("ctx"),1))