Macro impl_filter_step 

macro_rules! impl_filter_step {
    ($step:ty, $name:literal) => { ... };
}

Helper macro to implement Step for simple filter steps.

Filter steps pass through or reject traversers based on a predicate. The step struct must:

• Implement Clone
• Have a matches(&self, ctx: &ExecutionContext, traverser: &Traverser) -> bool method

Example

#[derive(Clone)]
struct IsPositiveStep;

impl IsPositiveStep {
    fn matches(&self, _ctx: &ExecutionContext, traverser: &Traverser) -> bool {
        matches!(&traverser.value, Value::Int(n) if *n > 0)
    }
}

impl_filter_step!(IsPositiveStep, "isPositive");

Streaming Support

For streaming execution, filter steps using this macro must also implement matches_streaming(&self, ctx: &StreamingContext, traverser: &Traverser) -> bool. If you don’t need streaming support yet, the macro provides a default pass-through that can be overridden by also implementing matches_streaming.