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Diffstat (limited to 'rust/syn/precedence.rs')
| -rw-r--r-- | rust/syn/precedence.rs | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/rust/syn/precedence.rs b/rust/syn/precedence.rs new file mode 100644 index 000000000000..cc4dba24a433 --- /dev/null +++ b/rust/syn/precedence.rs @@ -0,0 +1,212 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +#[cfg(all(feature = "printing", feature = "full"))] +use crate::attr::{AttrStyle, Attribute}; +#[cfg(feature = "printing")] +use crate::expr::Expr; +#[cfg(all(feature = "printing", feature = "full"))] +use crate::expr::{ + ExprArray, ExprAsync, ExprAwait, ExprBlock, ExprBreak, ExprCall, ExprConst, ExprContinue, + ExprField, ExprForLoop, ExprGroup, ExprIf, ExprIndex, ExprInfer, ExprLit, ExprLoop, ExprMacro, + ExprMatch, ExprMethodCall, ExprParen, ExprPath, ExprRepeat, ExprReturn, ExprStruct, ExprTry, + ExprTryBlock, ExprTuple, ExprUnsafe, ExprWhile, ExprYield, +}; +use crate::op::BinOp; +#[cfg(all(feature = "printing", feature = "full"))] +use crate::ty::ReturnType; +use std::cmp::Ordering; + +// Reference: https://doc.rust-lang.org/reference/expressions.html#expression-precedence +pub(crate) enum Precedence { + // return, break, closures + Jump, + // = += -= *= /= %= &= |= ^= <<= >>= + Assign, + // .. ..= + Range, + // || + Or, + // && + And, + // let + #[cfg(feature = "printing")] + Let, + // == != < > <= >= + Compare, + // | + BitOr, + // ^ + BitXor, + // & + BitAnd, + // << >> + Shift, + // + - + Sum, + // * / % + Product, + // as + Cast, + // unary - * ! & &mut + #[cfg(feature = "printing")] + Prefix, + // paths, loops, function calls, array indexing, field expressions, method calls + #[cfg(feature = "printing")] + Unambiguous, +} + +impl Precedence { + pub(crate) const MIN: Self = Precedence::Jump; + + pub(crate) fn of_binop(op: &BinOp) -> Self { + match op { + BinOp::Add(_) | BinOp::Sub(_) => Precedence::Sum, + BinOp::Mul(_) | BinOp::Div(_) | BinOp::Rem(_) => Precedence::Product, + BinOp::And(_) => Precedence::And, + BinOp::Or(_) => Precedence::Or, + BinOp::BitXor(_) => Precedence::BitXor, + BinOp::BitAnd(_) => Precedence::BitAnd, + BinOp::BitOr(_) => Precedence::BitOr, + BinOp::Shl(_) | BinOp::Shr(_) => Precedence::Shift, + + BinOp::Eq(_) + | BinOp::Lt(_) + | BinOp::Le(_) + | BinOp::Ne(_) + | BinOp::Ge(_) + | BinOp::Gt(_) => Precedence::Compare, + + BinOp::AddAssign(_) + | BinOp::SubAssign(_) + | BinOp::MulAssign(_) + | BinOp::DivAssign(_) + | BinOp::RemAssign(_) + | BinOp::BitXorAssign(_) + | BinOp::BitAndAssign(_) + | BinOp::BitOrAssign(_) + | BinOp::ShlAssign(_) + | BinOp::ShrAssign(_) => Precedence::Assign, + } + } + + #[cfg(feature = "printing")] + pub(crate) fn of(e: &Expr) -> Self { + #[cfg(feature = "full")] + fn prefix_attrs(attrs: &[Attribute]) -> Precedence { + for attr in attrs { + if let AttrStyle::Outer = attr.style { + return Precedence::Prefix; + } + } + Precedence::Unambiguous + } + + match e { + #[cfg(feature = "full")] + Expr::Closure(e) => match e.output { + ReturnType::Default => Precedence::Jump, + ReturnType::Type(..) => prefix_attrs(&e.attrs), + }, + + #[cfg(feature = "full")] + Expr::Break(ExprBreak { expr, .. }) + | Expr::Return(ExprReturn { expr, .. }) + | Expr::Yield(ExprYield { expr, .. }) => match expr { + Some(_) => Precedence::Jump, + None => Precedence::Unambiguous, + }, + + Expr::Assign(_) => Precedence::Assign, + Expr::Range(_) => Precedence::Range, + Expr::Binary(e) => Precedence::of_binop(&e.op), + Expr::Let(_) => Precedence::Let, + Expr::Cast(_) => Precedence::Cast, + Expr::RawAddr(_) | Expr::Reference(_) | Expr::Unary(_) => Precedence::Prefix, + + #[cfg(feature = "full")] + Expr::Array(ExprArray { attrs, .. }) + | Expr::Async(ExprAsync { attrs, .. }) + | Expr::Await(ExprAwait { attrs, .. }) + | Expr::Block(ExprBlock { attrs, .. }) + | Expr::Call(ExprCall { attrs, .. }) + | Expr::Const(ExprConst { attrs, .. }) + | Expr::Continue(ExprContinue { attrs, .. }) + | Expr::Field(ExprField { attrs, .. }) + | Expr::ForLoop(ExprForLoop { attrs, .. }) + | Expr::Group(ExprGroup { attrs, .. }) + | Expr::If(ExprIf { attrs, .. }) + | Expr::Index(ExprIndex { attrs, .. }) + | Expr::Infer(ExprInfer { attrs, .. }) + | Expr::Lit(ExprLit { attrs, .. }) + | Expr::Loop(ExprLoop { attrs, .. }) + | Expr::Macro(ExprMacro { attrs, .. }) + | Expr::Match(ExprMatch { attrs, .. }) + | Expr::MethodCall(ExprMethodCall { attrs, .. }) + | Expr::Paren(ExprParen { attrs, .. }) + | Expr::Path(ExprPath { attrs, .. }) + | Expr::Repeat(ExprRepeat { attrs, .. }) + | Expr::Struct(ExprStruct { attrs, .. }) + | Expr::Try(ExprTry { attrs, .. }) + | Expr::TryBlock(ExprTryBlock { attrs, .. }) + | Expr::Tuple(ExprTuple { attrs, .. }) + | Expr::Unsafe(ExprUnsafe { attrs, .. }) + | Expr::While(ExprWhile { attrs, .. }) => prefix_attrs(attrs), + + #[cfg(not(feature = "full"))] + Expr::Array(_) + | Expr::Async(_) + | Expr::Await(_) + | Expr::Block(_) + | Expr::Call(_) + | Expr::Const(_) + | Expr::Continue(_) + | Expr::Field(_) + | Expr::ForLoop(_) + | Expr::Group(_) + | Expr::If(_) + | Expr::Index(_) + | Expr::Infer(_) + | Expr::Lit(_) + | Expr::Loop(_) + | Expr::Macro(_) + | Expr::Match(_) + | Expr::MethodCall(_) + | Expr::Paren(_) + | Expr::Path(_) + | Expr::Repeat(_) + | Expr::Struct(_) + | Expr::Try(_) + | Expr::TryBlock(_) + | Expr::Tuple(_) + | Expr::Unsafe(_) + | Expr::While(_) => Precedence::Unambiguous, + + Expr::Verbatim(_) => Precedence::Unambiguous, + + #[cfg(not(feature = "full"))] + Expr::Break(_) | Expr::Closure(_) | Expr::Return(_) | Expr::Yield(_) => unreachable!(), + } + } +} + +impl Copy for Precedence {} + +impl Clone for Precedence { + fn clone(&self) -> Self { + *self + } +} + +impl PartialEq for Precedence { + fn eq(&self, other: &Self) -> bool { + *self as u8 == *other as u8 + } +} + +impl PartialOrd for Precedence { + fn partial_cmp(&self, other: &Self) -> Option<Ordering> { + let this = *self as u8; + let other = *other as u8; + Some(this.cmp(&other)) + } +} |