Value Constructor Expressions

In XPRESS, literal values are written as text contained with an XML element. The element name is the name of a function, and the literal text is the argument to the function. The following functions are provided for constructing simple atomic data types.

array Function

Builds a value of type list by evaluating each of the argument expressions and concatenating the return values. The expression can take multiple arguments. Null values are not filtered.

Example

<array>
   <s>apples</s>
   <s>oranges</s>
   <s>wiper blades</s>
</array>

i Function

Constructs an integer value. The function takes one argument, which must be literal text. The text should contain only numeric digits and can be optionally preceded by a plus or minus.

Example 1

<i>0</i>

Example 2

<i>42</i>

Example 3

<i>-1234</i>

list Function

Builds a value of type list by evaluating each of the argument expressions and concatenating the return values. The expression can take multiple arguments. Null values will be filtered.

Example

<list>
   <s>apples</s>
   <s>oranges</s>
   <s>wiper blades</s>
</list>

map Function

Creates a map that consists of the key-value pairs of each subexpression.

Example

<map>
   <!--Key 1-->
   <!--Value 1-->
   <!--Key n-->
   <!--Value n-->
</map>

null Function

Constructs a null value.

Example 1

<null/>

Example 2

<null></null>

s Function

Constructs a string value. The function takes one argument, which must be literal text. (Length is constrained only by the amount of contiguous memory available in your Java environment.)

Example

<s>Now is the time</s>