opendp 0.14.2-dev.20260401.2

A library of differential privacy algorithms for the statistical analysis of sensitive private data.
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use opendp_derive::bootstrap;

use crate::{
    combinators::FixDeltaMeasure,
    core::{FfiResult, Measurement, PrivacyMap},
    error::Fallible,
    ffi::any::{AnyMeasure, AnyMeasurement, AnyObject, Downcast},
    measures::{Approximate, SmoothedMaxDivergence},
};

#[bootstrap(features("contrib"), arguments(measurement(rust_type = b"null"),))]
/// Fix the delta parameter in the privacy map of a `measurement` with a SmoothedMaxDivergence output measure.
///
/// # Arguments
/// * `measurement` - a measurement with a privacy curve to be fixed
/// * `delta` - parameter to fix the privacy curve with
fn make_fix_delta(measurement: &AnyMeasurement, delta: f64) -> Fallible<AnyMeasurement> {
    fn monomorphize<MO: 'static + FixDeltaMeasure>(
        meas: &AnyMeasurement,
        delta: f64,
    ) -> Fallible<AnyMeasurement> {
        let privacy_map = meas.privacy_map.clone();
        let meas = Measurement::new(
            meas.input_domain.clone(),
            meas.input_metric.clone(),
            meas.output_measure.downcast_ref::<MO>()?.clone(),
            meas.function.clone(),
            PrivacyMap::new_fallible(move |d_in: &AnyObject| {
                privacy_map.eval(d_in)?.downcast::<MO::Distance>()
            }),
        )?;
        let meas = super::make_fix_delta(&meas, delta)?;
        let privacy_map = meas.privacy_map.clone();
        Measurement::new(
            meas.input_domain.clone(),
            meas.input_metric.clone(),
            AnyMeasure::new(meas.output_measure.clone()),
            meas.function.clone(),
            PrivacyMap::new_fallible(move |d_in: &AnyObject| {
                Ok(AnyObject::new(privacy_map.eval(d_in)?))
            }),
        )
    }

    let MO = measurement.output_measure.type_.clone();
    dispatch!(
        monomorphize,
        [(MO, [SmoothedMaxDivergence, Approximate<SmoothedMaxDivergence>])],
        (measurement, delta)
    )
}

#[unsafe(no_mangle)]
pub extern "C" fn opendp_combinators__make_fix_delta(
    measurement: *const AnyMeasurement,
    delta: f64,
) -> FfiResult<*mut AnyMeasurement> {
    // run combinator on measurement
    make_fix_delta(try_as_ref!(measurement), delta).into()
}