How to store the AST?

[mortenson]

Hi there, I'm just starting to use cel-go and was reading https://codelabs.developers.google.com/codelabs/cel-go#1, which mentions

There are three phases in processing an expression: parse, check, and evaluate. The most common pattern for CEL is for a control plane to parse and check expressions at config time, and store the AST.

How should the AST be stored? Is there a code example for serializing the AST?

[jnthntatum]

It's normally stored or transferred between programs in the protobuf format. See cel.AstToCheckedExpr for converting from the go object to proto. The conformance server harness has some examples (though the proto serialization is handled by grpc). See https://github.com/google/cel-go/blob/master/server/server.go and https://github.com/google/cel-spec/blob/master/tools/celrpc/celrpc.go

The protobuf dev guide has examples for reading/writing the serialized messages.

[mortenson]

Thank you!