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use crate::{AnalysisContext, Finding, Plugin, Severity, SmellCategory, func_location};
/// Detect functions with high cognitive complexity.
///
/// Cognitive complexity measures how hard code is to *understand*, unlike
/// cyclomatic complexity which measures testability. It penalizes nesting
/// and rewards linear, readable structures like `switch`.
///
/// ## References
///
/// [1] G. A. Campbell, "Cognitive Complexity: A new way of measuring
/// understandability," SonarSource, 2017.
/// https://www.sonarsource.com/resources/white-papers/cognitive-complexity/
pub struct CognitiveComplexityAnalyzer {
pub threshold: usize,
}
impl Default for CognitiveComplexityAnalyzer {
fn default() -> Self {
Self { threshold: 15 }
}
}
impl Plugin for CognitiveComplexityAnalyzer {
fn name(&self) -> &str {
"cognitive_complexity"
}
fn smells(&self) -> Vec<String> {
vec!["cognitive_complexity".into()]
}
fn description(&self) -> &str {
"Cognitive complexity exceeds threshold"
}
fn analyze(&self, ctx: &AnalysisContext) -> Vec<Finding> {
ctx.model
.functions
.iter()
.filter(|f| f.cognitive_complexity > self.threshold)
.map(|f| {
let severity = if f.cognitive_complexity > self.threshold * 2 {
Severity::Error
} else {
Severity::Warning
};
Finding {
smell_name: "cognitive_complexity".into(),
category: SmellCategory::Bloaters,
severity,
location: func_location(&ctx.file.path, f),
message: format!(
"Function `{}` has cognitive complexity {} (threshold: {})",
f.name, f.cognitive_complexity, self.threshold
),
suggested_refactorings: vec![
"Extract Method".into(),
"Replace Nested Conditional with Guard Clauses".into(),
],
actual_value: Some(f.cognitive_complexity as f64),
threshold: Some(self.threshold as f64),
}
})
.collect()
}
}