Expr class final

Represents a textual expression in the Common Expression Language (CEL) syntax. CEL is a C-like expression language. The syntax and semantics of CEL are documented at https://github.com/google/cel-spec.

Example (Comparison):

title: "Summary size limit"
description: "Determines if a summary is less than 100 chars"
expression: "document.summary.size() < 100"

Example (Equality):

title: "Requestor is owner"
description: "Determines if requestor is the document owner"
expression: "document.owner == request.auth.claims.email"

Example (Logic):

title: "Public documents"
description: "Determine whether the document should be publicly visible"
expression: "document.type != 'private' && document.type != 'internal'"

Example (Data Manipulation):

title: "Notification string"
description: "Create a notification string with a timestamp."
expression: "'New message received at ' + string(document.create_time)"

The exact variables and functions that may be referenced within an expression are determined by the service that evaluates it. See the service documentation for additional information.