VIATRA/Query/UserDocumentation/PureWhitelist

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This page is not updated anymore; for more up-to-date details look at the query language documentation at https://www.eclipse.org/viatra/documentation/query-language.html instead.

By default, check()/eval() constraints do not support calling arbitrary Java methods, since they are generally assumed to be impure. However, if you have a pure method and want to call it in these types of constraints, you have two options:

• if it is implemented by you, annotate it with the @Pure annotation of Xbase (org.eclipse.xtext.xbase.lib.Pure)
• if it comes from a third-party library, register it via the org.eclipse.viatra.query.patternlanguage.purewhitelist extension point

Some standard library methods are marked as pure by default, including:

• java.lang.Math
• java.lang.String