Policy Rule XML Capabilities

You can perform the following operations and use the following features in policy rules:

Searches within Lists (defined in the Configuration Management > Job Management > Lists page) of comma-delimited values to enforce consistency and reduce the number of rules needed to perform similar tasks. Enables better integration of scripts and policies (for example, see Using List Searches);
Calling a Policy Rule from within another Rule –The new PolicyRuleCall element may be used to call one rule from within another. This enables improved re-use of rule logic and works something like a function call. The caller may override the severity of the called rule;
Configuration block checks – supplements or replaces the CPD functionality used in the CPD editor. It allows you to break a configuration file into blocks, and then perform analysis on each of those blocks. These may be nested as desired by the administrator writing the rule. For more information, see Using Configuration Block Checks;
Use expressions to perform logical and mathematical operations, and for reading variables. You use the Expr element to perform these and other actions (for more information, see Regular Expressions in Policy Rules and the section Using the Expression <Expr> Element);
Support for arrays. Array indices begin at Zero. In XML rules, the Expr element can use the following operators to work with arrays:

`array`	Convert child expressions into an array.
`element-at`	Return the element at a specific array index.
`push`	Add one or more elements to the end of an array.
`pop`	Remove and return the last element of an array.
`unshift`	Add one or more elements to the beginning of an array.
`shift`	Remove and return the element at the beginning of an array.
`join`	Convert an array to a delimited string.
`size`	Return the size of an array.
`delete-at`	Remove an element at a location in the array, moving later elements inward. Returns the removed element.
`insert-at`	Insert an element at a specified location in the array, moving later elements outward.
`assign-at`	Sets the value of an element in a specified location in the array, overwriting the existing element.
`in`	Determine if an array contains a specific value.
`not-in`	Determine if an array does not contain a specific value.

Looping. The Raw XML Editor supports two types of looping, including:
- ForEach, which loops through an array, executing the Do code block once in each array element until the condition is met. It takes the form:

<ForEach>
expression
   <Do>
    statements
    ...
   </Do>
</ForEach>

While, which loops until a condition is met. It takes the form:

<While>
expression
   <Do>
    statements
    ...
   </Do>
</While>

A new Map element enables a transformation of all elements in an array, by executing a block of statements for each element in the array, returning a rewritten array as the result. It takes the form:

<Map>
expression
   <Do>
    statements
    ...
   </Do>
</Map>

The expression is evaluated as an array; for each element, a variable (using the default name _map_value) is automatically set and the rule executes the Do code block.
Map and ForEach differ because the return value of ForEach is the value of the last executed statement in the Do block; the return value of the Map element is an array, with each entry being the return value of the Do block for the corresponding entry in the input array. For example, the following code block produces a variable called newarray that contains the values 1, 2, 3, and 4:

<Map output="newarray">
<Expr op="array">
   <Expr value="0"/>
   <Expr value="1"/>
   <Expr value="2"/>
   <Expr value="3"/>
</Expr>
<Do>
<Expr op="+">
    <Expr variable="_map_value"/>
    <Expr value="1"/>
   </Expr>
</Do>
</Map>

An example of this type can be useful in combination with methods accessible on an object. The following code block produces an array of interface names:

<Map output="interface_names">
<Expr field="interfaces"/>
<Do>
<Expr object="_map_value" field="ifName"/>
</Do>
</Map>