alint_rules/
max_directory_depth.rs

1//! `max_directory_depth` — cap the depth of any path in scope.
2//!
3//! Depth is the number of `/`-separated components in the path.
4//! `README.md` is depth 1; `src/lib.rs` is depth 2; `a/b/c/d.rs`
5//! is depth 4. Flags one violation per path that exceeds the cap.
6//!
7//! Check-only: moving files around to flatten the tree isn't a
8//! decision alint can make automatically.
9
10use alint_core::{Context, Error, Level, Result, Rule, RuleSpec, Scope, Violation};
11use serde::Deserialize;
12
13#[derive(Debug, Deserialize)]
14#[serde(deny_unknown_fields)]
15struct Options {
16    max_depth: usize,
17}
18
19#[derive(Debug)]
20pub struct MaxDirectoryDepthRule {
21    id: String,
22    level: Level,
23    policy_url: Option<String>,
24    message: Option<String>,
25    scope: Scope,
26    max_depth: usize,
27}
28
29impl Rule for MaxDirectoryDepthRule {
30    fn id(&self) -> &str {
31        &self.id
32    }
33    fn level(&self) -> Level {
34        self.level
35    }
36    fn policy_url(&self) -> Option<&str> {
37        self.policy_url.as_deref()
38    }
39
40    fn evaluate(&self, ctx: &Context<'_>) -> Result<Vec<Violation>> {
41        let mut violations = Vec::new();
42        for entry in ctx.index.files() {
43            if !self.scope.matches(&entry.path) {
44                continue;
45            }
46            let depth = entry.path.components().count();
47            if depth > self.max_depth {
48                let msg = self.message.clone().unwrap_or_else(|| {
49                    format!(
50                        "{} is at depth {depth}; max is {}",
51                        entry.path.display(),
52                        self.max_depth
53                    )
54                });
55                violations.push(Violation::new(msg).with_path(&entry.path));
56            }
57        }
58        Ok(violations)
59    }
60}
61
62pub fn build(spec: &RuleSpec) -> Result<Box<dyn Rule>> {
63    let paths = spec.paths.as_ref().ok_or_else(|| {
64        Error::rule_config(
65            &spec.id,
66            "max_directory_depth requires a `paths` field (often `\"**\"`)",
67        )
68    })?;
69    let opts: Options = spec
70        .deserialize_options()
71        .map_err(|e| Error::rule_config(&spec.id, format!("invalid options: {e}")))?;
72    if opts.max_depth == 0 {
73        return Err(Error::rule_config(
74            &spec.id,
75            "max_directory_depth `max_depth` must be > 0",
76        ));
77    }
78    if spec.fix.is_some() {
79        return Err(Error::rule_config(
80            &spec.id,
81            "max_directory_depth has no fix op — moving files is a human decision",
82        ));
83    }
84    Ok(Box::new(MaxDirectoryDepthRule {
85        id: spec.id.clone(),
86        level: spec.level,
87        policy_url: spec.policy_url.clone(),
88        message: spec.message.clone(),
89        scope: Scope::from_paths_spec(paths)?,
90        max_depth: opts.max_depth,
91    }))
92}
93
94#[cfg(test)]
95mod tests {
96    use std::path::PathBuf;
97
98    fn depth_of(s: &str) -> usize {
99        PathBuf::from(s).components().count()
100    }
101
102    #[test]
103    fn depth_counts_components() {
104        assert_eq!(depth_of("README.md"), 1);
105        assert_eq!(depth_of("src/lib.rs"), 2);
106        assert_eq!(depth_of("a/b/c/d.rs"), 4);
107    }
108}
alint_rules/max_directory_depth.rs

alint_rules/
max_directory_depth.rs
