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