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//! `file_max_lines` — files in scope must have AT MOST
//! `max_lines` lines. Mirror of [`crate::file_min_lines`];
//! shares the line-counting semantics so the two compose
//! cleanly when both are applied to the same file.
//!
//! Catches the "everything-module" anti-pattern — a single
//! `lib.rs` / `index.ts` / `helpers.py` that grew until it
//! does the work of a half-dozen smaller files. The threshold
//! is intentionally a soft signal rather than a hard limit;
//! we ship it at `level: warning` in tutorials and rulesets,
//! and leave the cap value to the team.
use alint_core::{Context, Error, Level, Result, Rule, RuleSpec, Scope, Violation};
use serde::Deserialize;
#[derive(Debug, Deserialize)]
struct Options {
max_lines: u64,
}
#[derive(Debug)]
pub struct FileMaxLinesRule {
id: String,
level: Level,
policy_url: Option<String>,
message: Option<String>,
scope: Scope,
max_lines: u64,
}
impl Rule for FileMaxLinesRule {
fn id(&self) -> &str {
&self.id
}
fn level(&self) -> Level {
self.level
}
fn policy_url(&self) -> Option<&str> {
self.policy_url.as_deref()
}
fn evaluate(&self, ctx: &Context<'_>) -> Result<Vec<Violation>> {
let mut violations = Vec::new();
for entry in ctx.index.files() {
if !self.scope.matches(&entry.path) {
continue;
}
let full = ctx.root.join(&entry.path);
let Ok(bytes) = std::fs::read(&full) else {
// Same silent-skip policy as the rest of the
// content family — a permission flake or race
// shouldn't blow up the whole check run.
continue;
};
let lines = count_lines(&bytes);
if lines > self.max_lines {
let msg = self.message.clone().unwrap_or_else(|| {
format!(
"file has {} line(s); at most {} allowed",
lines, self.max_lines,
)
});
violations.push(Violation::new(msg).with_path(&entry.path));
}
}
Ok(violations)
}
}
/// Count lines with the same `wc -l`-style semantics as
/// `file_min_lines::count_lines`. Kept as a private function
/// here (rather than reused from `file_min_lines`) because
/// inlining it makes the unit tests explicit about what this
/// rule's threshold is being compared against — and the
/// implementation is one line, not worth a cross-module dep.
fn count_lines(bytes: &[u8]) -> u64 {
if bytes.is_empty() {
return 0;
}
#[allow(clippy::naive_bytecount)]
let newlines = bytes.iter().filter(|&&b| b == b'\n').count() as u64;
let trailing_unterminated = u64::from(!bytes.ends_with(b"\n"));
newlines + trailing_unterminated
}
pub fn build(spec: &RuleSpec) -> Result<Box<dyn Rule>> {
let Some(paths) = &spec.paths else {
return Err(Error::rule_config(
&spec.id,
"file_max_lines requires a `paths` field",
));
};
let opts: Options = spec
.deserialize_options()
.map_err(|e| Error::rule_config(&spec.id, format!("invalid options: {e}")))?;
Ok(Box::new(FileMaxLinesRule {
id: spec.id.clone(),
level: spec.level,
policy_url: spec.policy_url.clone(),
message: spec.message.clone(),
scope: Scope::from_paths_spec(paths)?,
max_lines: opts.max_lines,
}))
}
#[cfg(test)]
mod tests {
use super::count_lines;
#[test]
fn empty_file_is_zero_lines() {
assert_eq!(count_lines(b""), 0);
}
#[test]
fn matches_min_lines_semantics() {
// Identical accounting to file_min_lines so the two
// rules agree on what "this file has N lines" means.
assert_eq!(count_lines(b"a\n"), 1);
assert_eq!(count_lines(b"a\nb\n"), 2);
assert_eq!(count_lines(b"a\nb"), 2);
assert_eq!(count_lines(b"\n\n"), 2);
assert_eq!(count_lines(b"a\n\nb\n"), 3);
}
}