rust-clippy/clippy_lints/src/utils/comparisons.rs
2020-01-07 01:46:33 +09:00

36 lines
927 B
Rust

//! Utility functions about comparison operators.
#![deny(clippy::missing_docs_in_private_items)]
use rustc_hir::{BinOpKind, Expr};
#[derive(PartialEq, Eq, Debug, Copy, Clone)]
/// Represent a normalized comparison operator.
pub enum Rel {
/// `<`
Lt,
/// `<=`
Le,
/// `==`
Eq,
/// `!=`
Ne,
}
/// Put the expression in the form `lhs < rhs`, `lhs <= rhs`, `lhs == rhs` or
/// `lhs != rhs`.
pub fn normalize_comparison<'a>(
op: BinOpKind,
lhs: &'a Expr<'a>,
rhs: &'a Expr<'a>,
) -> Option<(Rel, &'a Expr<'a>, &'a Expr<'a>)> {
match op {
BinOpKind::Lt => Some((Rel::Lt, lhs, rhs)),
BinOpKind::Le => Some((Rel::Le, lhs, rhs)),
BinOpKind::Gt => Some((Rel::Lt, rhs, lhs)),
BinOpKind::Ge => Some((Rel::Le, rhs, lhs)),
BinOpKind::Eq => Some((Rel::Eq, rhs, lhs)),
BinOpKind::Ne => Some((Rel::Ne, rhs, lhs)),
_ => None,
}
}