use super::*;
use std::{convert::Infallible, str};
use full_moon::{
ast::{self, Ast},
node::Node,
visitors::Visitor,
};
pub struct SuspiciousReverseLoopLint;
impl Rule for SuspiciousReverseLoopLint {
type Config = ();
type Error = Infallible;
fn new(_: Self::Config) -> Result<Self, Self::Error> {
Ok(SuspiciousReverseLoopLint)
}
fn pass(&self, ast: &Ast, _: &Context) -> Vec<Diagnostic> {
let mut visitor = SuspiciousReverseLoopVisitor {
positions: Vec::new(),
};
visitor.visit_ast(&ast);
visitor
.positions
.iter()
.map(|position| {
Diagnostic::new_complete(
"suspicious_reverse_loop",
"this loop will only ever run once at most".to_owned(),
Label::new(*position),
vec!["help: try adding `, -1` after `1`".to_owned()],
Vec::new(),
)
})
.collect()
}
fn severity(&self) -> Severity {
Severity::Error
}
fn rule_type(&self) -> RuleType {
RuleType::Correctness
}
}
struct SuspiciousReverseLoopVisitor {
positions: Vec<(usize, usize)>,
}
impl Visitor<'_> for SuspiciousReverseLoopVisitor {
fn visit_numeric_for(&mut self, node: &ast::NumericFor) {
if_chain::if_chain! {
if node.step().is_none();
if let ast::Expression::UnaryOperator { unop, .. } = node.start();
if let ast::UnOp::Hash(_) = unop;
if let ast::Expression::Value { value, binop, .. } = node.end();
if binop.is_none();
if let ast::Value::Number(number) = &**value;
if str::parse::<f32>(&number.token().to_string()).ok() <= Some(1.0);
then {
self.positions.push((
node.start().start_position().unwrap().bytes(),
node.end().end_position().unwrap().bytes(),
));
}
};
}
}
#[cfg(test)]
mod tests {
use super::{super::test_util::test_lint, *};
#[test]
fn test_suspicious_reverse_loop() {
test_lint(
SuspiciousReverseLoopLint::new(()).unwrap(),
"suspicious_reverse_loop",
"suspicious_reverse_loop",
);
}
}