rust / intermediate
Snippet
Efficient Map Updates with the Entry API
The Entry API allows you to check for a key's existence and perform an operation in a single step, avoiding double lookups and providing a more expressive way to handle conditional insertion.
snippet.rs
rust
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use std::collections::HashMap;let mut scores = HashMap::new();let team = String::from("Blue");scores.entry(team).and_modify(|e| *e += 10).or_insert(50);println!("{:?}", scores);
Breakdown
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scores.entry(team)
Returns an Entry enum representing either an occupied or vacant spot.
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and_modify(|e| *e += 10)
Applies a closure to the value if the entry is already occupied.
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or_insert(50)
Inserts the provided value if the entry is vacant, returning a mutable reference.