Optimize name transformations #401
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These can be run at compile time. Previously they were run at runtime on every invocation of the codec. This was particularly expensive for some of the builtins like the snake_case codec as it was allocating and compiling a Pattern instance per member field per invocation of the codec
at compile time ``` //This fails without the @nowarn annotation object Person { val transform: String => String = _.toLowerCase() @nowarn("msg=Failed to transform member names at compile time") implicit val decoderForPerson: Decoder[Person] = deriveDecoder[Person](transform, true, None) } ``` ``` //This is ok object Person { implicit val decoderForPerson: Decoder[Person] = deriveDecoder[Person]((s: String) => s.toLowerCase(), true, None)} ```
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Possibly the compiler warning could have a suggestion of how to fix provided transformations so that they're expanded at compile time but I'm not really sure what the rules are. I will update this ASAP with a change to add some tests for when we can't expand at compile time as I doubt that the existing tests cover this |
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Apologies for opening this in a half-finished state. I didn't realize at first that we can't always do the transformation at compile time due to limitations in |
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In most cases (in particular for the builtin snake case and kebab case) the name transformations can be expanded at compile time. Previously they were run at runtime on every invocation of the codec. This was particularly expensive for some of the builtins like the snake_case codec as it was allocating and compiling a Pattern instance per member field per invocation of the codec.
Note however that we do need a fallback to the previous implementation for some user-provided transformations eg