Based on Cognitive Complexity by G. Ann Campbell.
Add complexity to your Cargo.toml.
[dependencies]
complexity = "0.1"
syn = "1"
You'll need to import the [Complexity] trait, and probably some parts of
[syn].
rust
use complexity::Complexity;
use syn::{ItemFn, parse_str};
Loops and branching increment the complexity by one each. Additionally,
continue and break statements increment the complexity by one.
```rust let code = r#" fn sumofprimes(max: u64) -> u64 { let mut total = 0; 'outer: for i in 1..=max { for j in 2..i { if i % j == 0 { continue 'outer; } } total += i; } }"#;
let func: ItemFn = parsestr(code)?; asserteq!(func.complexity(), 7); ```
However, a match only increases the complexity by one no matter how many
branches there are.
```rust let code = r#" fn get_words(number: u64) -> &'static str { match number { 1 => "one", 2 => "a couple", 3 => "a few", _ => "lots", } }"#;
let func: ItemFn = parsestr(code)?; asserteq!(func.complexity(), 1); ```
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