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🔑 added max_by_key #73

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🔑 added max_by_key #73

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22 changes: 22 additions & 0 deletions ndc_lib/src/stdlib/sequence.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -111,6 +111,28 @@ mod inner {
Sequence::Deque(d) => d.try_borrow()?.iter().try_max(),
}
}
pub fn max_by_key(seq: &mut Sequence, func: &Callable<'_>) -> EvaluationResult {
let mut best_value = None;
let mut best_key = None;

for value in mut_seq_to_iterator(seq) {
if let Some(best_key_val) = &best_key {
let new_key = func.call(&mut [value.clone()])?;
if &new_key > best_key_val {
best_key = Some(new_key);
best_value = Some(value);
}
} else {
best_key = Some(func.call(&mut [value.clone()])?);
best_value = Some(value);
}
}

match best_value {
None => Err(anyhow::anyhow!("empty input to max_by_key"))?,
Some(value) => Ok(value),
}
}

/// Returns the lowest element in the sequence.
pub fn min(seq: &Sequence) -> anyhow::Result<Value> {
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