Evaluating expressions

Expressions are evaluated based on the context in which data object names, literals, operators, function names and map names appear in the expression, and the data on which it operates. A component rule always evaluates once for each occurrence of a component. A map rule can evaluate many times.

When a map rule evaluates, the map designer selects an evaluation set of values and then evaluates the rule. Then it selects another evaluation set of values, if there is one, and evaluates the rule again. This continues until all the different evaluation sets have been used.

The same number of evaluations is always produced, but output objects can be ordered differently, depending on how you define your map.

For a selected evaluation set, a particular instance of a rule is evaluated using parentheses, operator precedence rules, and left-to-right precedence rules to get one result.


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