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Diffstat (limited to 'rust/syn/expr.rs')
| -rw-r--r-- | rust/syn/expr.rs | 4175 |
1 files changed, 4175 insertions, 0 deletions
diff --git a/rust/syn/expr.rs b/rust/syn/expr.rs new file mode 100644 index 000000000000..deb918436604 --- /dev/null +++ b/rust/syn/expr.rs @@ -0,0 +1,4175 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +use crate::attr::Attribute; +#[cfg(all(feature = "parsing", feature = "full"))] +use crate::error::Result; +#[cfg(feature = "parsing")] +use crate::ext::IdentExt as _; +#[cfg(feature = "full")] +use crate::generics::BoundLifetimes; +use crate::ident::Ident; +#[cfg(any(feature = "parsing", feature = "full"))] +use crate::lifetime::Lifetime; +use crate::lit::Lit; +use crate::mac::Macro; +use crate::op::{BinOp, UnOp}; +#[cfg(feature = "parsing")] +use crate::parse::ParseStream; +#[cfg(feature = "full")] +use crate::pat::Pat; +use crate::path::{AngleBracketedGenericArguments, Path, QSelf}; +use crate::punctuated::Punctuated; +#[cfg(feature = "full")] +use crate::stmt::Block; +use crate::token; +#[cfg(feature = "full")] +use crate::ty::ReturnType; +use crate::ty::Type; +use proc_macro2::{Span, TokenStream}; +#[cfg(feature = "printing")] +use quote::IdentFragment; +#[cfg(feature = "printing")] +use std::fmt::{self, Display}; +use std::hash::{Hash, Hasher}; +#[cfg(all(feature = "parsing", feature = "full"))] +use std::mem; + +ast_enum_of_structs! { + /// A Rust expression. + /// + /// *This type is available only if Syn is built with the `"derive"` or `"full"` + /// feature, but most of the variants are not available unless "full" is enabled.* + /// + /// # Syntax tree enums + /// + /// This type is a syntax tree enum. In Syn this and other syntax tree enums + /// are designed to be traversed using the following rebinding idiom. + /// + /// ``` + /// # use syn::Expr; + /// # + /// # fn example(expr: Expr) { + /// # const IGNORE: &str = stringify! { + /// let expr: Expr = /* ... */; + /// # }; + /// match expr { + /// Expr::MethodCall(expr) => { + /// /* ... */ + /// } + /// Expr::Cast(expr) => { + /// /* ... */ + /// } + /// Expr::If(expr) => { + /// /* ... */ + /// } + /// + /// /* ... */ + /// # _ => {} + /// # } + /// # } + /// ``` + /// + /// We begin with a variable `expr` of type `Expr` that has no fields + /// (because it is an enum), and by matching on it and rebinding a variable + /// with the same name `expr` we effectively imbue our variable with all of + /// the data fields provided by the variant that it turned out to be. So for + /// example above if we ended up in the `MethodCall` case then we get to use + /// `expr.receiver`, `expr.args` etc; if we ended up in the `If` case we get + /// to use `expr.cond`, `expr.then_branch`, `expr.else_branch`. + /// + /// This approach avoids repeating the variant names twice on every line. + /// + /// ``` + /// # use syn::{Expr, ExprMethodCall}; + /// # + /// # fn example(expr: Expr) { + /// // Repetitive; recommend not doing this. + /// match expr { + /// Expr::MethodCall(ExprMethodCall { method, args, .. }) => { + /// # } + /// # _ => {} + /// # } + /// # } + /// ``` + /// + /// In general, the name to which a syntax tree enum variant is bound should + /// be a suitable name for the complete syntax tree enum type. + /// + /// ``` + /// # use syn::{Expr, ExprField}; + /// # + /// # fn example(discriminant: ExprField) { + /// // Binding is called `base` which is the name I would use if I were + /// // assigning `*discriminant.base` without an `if let`. + /// if let Expr::Tuple(base) = *discriminant.base { + /// # } + /// # } + /// ``` + /// + /// A sign that you may not be choosing the right variable names is if you + /// see names getting repeated in your code, like accessing + /// `receiver.receiver` or `pat.pat` or `cond.cond`. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + #[non_exhaustive] + pub enum Expr { + /// A slice literal expression: `[a, b, c, d]`. + Array(ExprArray), + + /// An assignment expression: `a = compute()`. + Assign(ExprAssign), + + /// An async block: `async { ... }`. + Async(ExprAsync), + + /// An await expression: `fut.await`. + Await(ExprAwait), + + /// A binary operation: `a + b`, `a += b`. + Binary(ExprBinary), + + /// A blocked scope: `{ ... }`. + Block(ExprBlock), + + /// A `break`, with an optional label to break and an optional + /// expression. + Break(ExprBreak), + + /// A function call expression: `invoke(a, b)`. + Call(ExprCall), + + /// A cast expression: `foo as f64`. + Cast(ExprCast), + + /// A closure expression: `|a, b| a + b`. + Closure(ExprClosure), + + /// A const block: `const { ... }`. + Const(ExprConst), + + /// A `continue`, with an optional label. + Continue(ExprContinue), + + /// Access of a named struct field (`obj.k`) or unnamed tuple struct + /// field (`obj.0`). + Field(ExprField), + + /// A for loop: `for pat in expr { ... }`. + ForLoop(ExprForLoop), + + /// An expression contained within invisible delimiters. + /// + /// This variant is important for faithfully representing the precedence + /// of expressions and is related to `None`-delimited spans in a + /// `TokenStream`. + Group(ExprGroup), + + /// An `if` expression with an optional `else` block: `if expr { ... } + /// else { ... }`. + /// + /// The `else` branch expression may only be an `If` or `Block` + /// expression, not any of the other types of expression. + If(ExprIf), + + /// A square bracketed indexing expression: `vector[2]`. + Index(ExprIndex), + + /// The inferred value of a const generic argument, denoted `_`. + Infer(ExprInfer), + + /// A `let` guard: `let Some(x) = opt`. + Let(ExprLet), + + /// A literal in place of an expression: `1`, `"foo"`. + Lit(ExprLit), + + /// Conditionless loop: `loop { ... }`. + Loop(ExprLoop), + + /// A macro invocation expression: `format!("{}", q)`. + Macro(ExprMacro), + + /// A `match` expression: `match n { Some(n) => {}, None => {} }`. + Match(ExprMatch), + + /// A method call expression: `x.foo::<T>(a, b)`. + MethodCall(ExprMethodCall), + + /// A parenthesized expression: `(a + b)`. + Paren(ExprParen), + + /// A path like `std::mem::replace` possibly containing generic + /// parameters and a qualified self-type. + /// + /// A plain identifier like `x` is a path of length 1. + Path(ExprPath), + + /// A range expression: `1..2`, `1..`, `..2`, `1..=2`, `..=2`. + Range(ExprRange), + + /// Address-of operation: `&raw const place` or `&raw mut place`. + RawAddr(ExprRawAddr), + + /// A referencing operation: `&a` or `&mut a`. + Reference(ExprReference), + + /// An array literal constructed from one repeated element: `[0u8; N]`. + Repeat(ExprRepeat), + + /// A `return`, with an optional value to be returned. + Return(ExprReturn), + + /// A struct literal expression: `Point { x: 1, y: 1 }`. + /// + /// The `rest` provides the value of the remaining fields as in `S { a: + /// 1, b: 1, ..rest }`. + Struct(ExprStruct), + + /// A try-expression: `expr?`. + Try(ExprTry), + + /// A try block: `try { ... }`. + TryBlock(ExprTryBlock), + + /// A tuple expression: `(a, b, c, d)`. + Tuple(ExprTuple), + + /// A unary operation: `!x`, `*x`. + Unary(ExprUnary), + + /// An unsafe block: `unsafe { ... }`. + Unsafe(ExprUnsafe), + + /// Tokens in expression position not interpreted by Syn. + Verbatim(TokenStream), + + /// A while loop: `while expr { ... }`. + While(ExprWhile), + + /// A yield expression: `yield expr`. + Yield(ExprYield), + + // For testing exhaustiveness in downstream code, use the following idiom: + // + // match expr { + // #![cfg_attr(test, deny(non_exhaustive_omitted_patterns))] + // + // Expr::Array(expr) => {...} + // Expr::Assign(expr) => {...} + // ... + // Expr::Yield(expr) => {...} + // + // _ => { /* some sane fallback */ } + // } + // + // This way we fail your tests but don't break your library when adding + // a variant. You will be notified by a test failure when a variant is + // added, so that you can add code to handle it, but your library will + // continue to compile and work for downstream users in the interim. + } +} + +ast_struct! { + /// A slice literal expression: `[a, b, c, d]`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprArray #full { + pub attrs: Vec<Attribute>, + pub bracket_token: token::Bracket, + pub elems: Punctuated<Expr, Token![,]>, + } +} + +ast_struct! { + /// An assignment expression: `a = compute()`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprAssign #full { + pub attrs: Vec<Attribute>, + pub left: Box<Expr>, + pub eq_token: Token![=], + pub right: Box<Expr>, + } +} + +ast_struct! { + /// An async block: `async { ... }`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprAsync #full { + pub attrs: Vec<Attribute>, + pub async_token: Token![async], + pub capture: Option<Token![move]>, + pub block: Block, + } +} + +ast_struct! { + /// An await expression: `fut.await`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprAwait #full { + pub attrs: Vec<Attribute>, + pub base: Box<Expr>, + pub dot_token: Token![.], + pub await_token: Token![await], + } +} + +ast_struct! { + /// A binary operation: `a + b`, `a += b`. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct ExprBinary { + pub attrs: Vec<Attribute>, + pub left: Box<Expr>, + pub op: BinOp, + pub right: Box<Expr>, + } +} + +ast_struct! { + /// A blocked scope: `{ ... }`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprBlock #full { + pub attrs: Vec<Attribute>, + pub label: Option<Label>, + pub block: Block, + } +} + +ast_struct! { + /// A `break`, with an optional label to break and an optional + /// expression. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprBreak #full { + pub attrs: Vec<Attribute>, + pub break_token: Token![break], + pub label: Option<Lifetime>, + pub expr: Option<Box<Expr>>, + } +} + +ast_struct! { + /// A function call expression: `invoke(a, b)`. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct ExprCall { + pub attrs: Vec<Attribute>, + pub func: Box<Expr>, + pub paren_token: token::Paren, + pub args: Punctuated<Expr, Token![,]>, + } +} + +ast_struct! { + /// A cast expression: `foo as f64`. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct ExprCast { + pub attrs: Vec<Attribute>, + pub expr: Box<Expr>, + pub as_token: Token![as], + pub ty: Box<Type>, + } +} + +ast_struct! { + /// A closure expression: `|a, b| a + b`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprClosure #full { + pub attrs: Vec<Attribute>, + pub lifetimes: Option<BoundLifetimes>, + pub constness: Option<Token![const]>, + pub movability: Option<Token![static]>, + pub asyncness: Option<Token![async]>, + pub capture: Option<Token![move]>, + pub or1_token: Token![|], + pub inputs: Punctuated<Pat, Token![,]>, + pub or2_token: Token![|], + pub output: ReturnType, + pub body: Box<Expr>, + } +} + +ast_struct! { + /// A const block: `const { ... }`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprConst #full { + pub attrs: Vec<Attribute>, + pub const_token: Token![const], + pub block: Block, + } +} + +ast_struct! { + /// A `continue`, with an optional label. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprContinue #full { + pub attrs: Vec<Attribute>, + pub continue_token: Token![continue], + pub label: Option<Lifetime>, + } +} + +ast_struct! { + /// Access of a named struct field (`obj.k`) or unnamed tuple struct + /// field (`obj.0`). + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct ExprField { + pub attrs: Vec<Attribute>, + pub base: Box<Expr>, + pub dot_token: Token![.], + pub member: Member, + } +} + +ast_struct! { + /// A for loop: `for pat in expr { ... }`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprForLoop #full { + pub attrs: Vec<Attribute>, + pub label: Option<Label>, + pub for_token: Token![for], + pub pat: Box<Pat>, + pub in_token: Token![in], + pub expr: Box<Expr>, + pub body: Block, + } +} + +ast_struct! { + /// An expression contained within invisible delimiters. + /// + /// This variant is important for faithfully representing the precedence + /// of expressions and is related to `None`-delimited spans in a + /// `TokenStream`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprGroup { + pub attrs: Vec<Attribute>, + pub group_token: token::Group, + pub expr: Box<Expr>, + } +} + +ast_struct! { + /// An `if` expression with an optional `else` block: `if expr { ... } + /// else { ... }`. + /// + /// The `else` branch expression may only be an `If` or `Block` + /// expression, not any of the other types of expression. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprIf #full { + pub attrs: Vec<Attribute>, + pub if_token: Token![if], + pub cond: Box<Expr>, + pub then_branch: Block, + pub else_branch: Option<(Token![else], Box<Expr>)>, + } +} + +ast_struct! { + /// A square bracketed indexing expression: `vector[2]`. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct ExprIndex { + pub attrs: Vec<Attribute>, + pub expr: Box<Expr>, + pub bracket_token: token::Bracket, + pub index: Box<Expr>, + } +} + +ast_struct! { + /// The inferred value of a const generic argument, denoted `_`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprInfer #full { + pub attrs: Vec<Attribute>, + pub underscore_token: Token![_], + } +} + +ast_struct! { + /// A `let` guard: `let Some(x) = opt`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprLet #full { + pub attrs: Vec<Attribute>, + pub let_token: Token![let], + pub pat: Box<Pat>, + pub eq_token: Token![=], + pub expr: Box<Expr>, + } +} + +ast_struct! { + /// A literal in place of an expression: `1`, `"foo"`. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct ExprLit { + pub attrs: Vec<Attribute>, + pub lit: Lit, + } +} + +ast_struct! { + /// Conditionless loop: `loop { ... }`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprLoop #full { + pub attrs: Vec<Attribute>, + pub label: Option<Label>, + pub loop_token: Token![loop], + pub body: Block, + } +} + +ast_struct! { + /// A macro invocation expression: `format!("{}", q)`. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct ExprMacro { + pub attrs: Vec<Attribute>, + pub mac: Macro, + } +} + +ast_struct! { + /// A `match` expression: `match n { Some(n) => {}, None => {} }`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprMatch #full { + pub attrs: Vec<Attribute>, + pub match_token: Token![match], + pub expr: Box<Expr>, + pub brace_token: token::Brace, + pub arms: Vec<Arm>, + } +} + +ast_struct! { + /// A method call expression: `x.foo::<T>(a, b)`. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct ExprMethodCall { + pub attrs: Vec<Attribute>, + pub receiver: Box<Expr>, + pub dot_token: Token![.], + pub method: Ident, + pub turbofish: Option<AngleBracketedGenericArguments>, + pub paren_token: token::Paren, + pub args: Punctuated<Expr, Token![,]>, + } +} + +ast_struct! { + /// A parenthesized expression: `(a + b)`. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct ExprParen { + pub attrs: Vec<Attribute>, + pub paren_token: token::Paren, + pub expr: Box<Expr>, + } +} + +ast_struct! { + /// A path like `std::mem::replace` possibly containing generic + /// parameters and a qualified self-type. + /// + /// A plain identifier like `x` is a path of length 1. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct ExprPath { + pub attrs: Vec<Attribute>, + pub qself: Option<QSelf>, + pub path: Path, + } +} + +ast_struct! { + /// A range expression: `1..2`, `1..`, `..2`, `1..=2`, `..=2`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprRange #full { + pub attrs: Vec<Attribute>, + pub start: Option<Box<Expr>>, + pub limits: RangeLimits, + pub end: Option<Box<Expr>>, + } +} + +ast_struct! { + /// Address-of operation: `&raw const place` or `&raw mut place`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprRawAddr #full { + pub attrs: Vec<Attribute>, + pub and_token: Token![&], + pub raw: Token![raw], + pub mutability: PointerMutability, + pub expr: Box<Expr>, + } +} + +ast_struct! { + /// A referencing operation: `&a` or `&mut a`. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct ExprReference { + pub attrs: Vec<Attribute>, + pub and_token: Token![&], + pub mutability: Option<Token![mut]>, + pub expr: Box<Expr>, + } +} + +ast_struct! { + /// An array literal constructed from one repeated element: `[0u8; N]`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprRepeat #full { + pub attrs: Vec<Attribute>, + pub bracket_token: token::Bracket, + pub expr: Box<Expr>, + pub semi_token: Token![;], + pub len: Box<Expr>, + } +} + +ast_struct! { + /// A `return`, with an optional value to be returned. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprReturn #full { + pub attrs: Vec<Attribute>, + pub return_token: Token![return], + pub expr: Option<Box<Expr>>, + } +} + +ast_struct! { + /// A struct literal expression: `Point { x: 1, y: 1 }`. + /// + /// The `rest` provides the value of the remaining fields as in `S { a: + /// 1, b: 1, ..rest }`. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct ExprStruct { + pub attrs: Vec<Attribute>, + pub qself: Option<QSelf>, + pub path: Path, + pub brace_token: token::Brace, + pub fields: Punctuated<FieldValue, Token![,]>, + pub dot2_token: Option<Token![..]>, + pub rest: Option<Box<Expr>>, + } +} + +ast_struct! { + /// A try-expression: `expr?`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprTry #full { + pub attrs: Vec<Attribute>, + pub expr: Box<Expr>, + pub question_token: Token![?], + } +} + +ast_struct! { + /// A try block: `try { ... }`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprTryBlock #full { + pub attrs: Vec<Attribute>, + pub try_token: Token![try], + pub block: Block, + } +} + +ast_struct! { + /// A tuple expression: `(a, b, c, d)`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprTuple { + pub attrs: Vec<Attribute>, + pub paren_token: token::Paren, + pub elems: Punctuated<Expr, Token![,]>, + } +} + +ast_struct! { + /// A unary operation: `!x`, `*x`. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct ExprUnary { + pub attrs: Vec<Attribute>, + pub op: UnOp, + pub expr: Box<Expr>, + } +} + +ast_struct! { + /// An unsafe block: `unsafe { ... }`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprUnsafe #full { + pub attrs: Vec<Attribute>, + pub unsafe_token: Token![unsafe], + pub block: Block, + } +} + +ast_struct! { + /// A while loop: `while expr { ... }`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprWhile #full { + pub attrs: Vec<Attribute>, + pub label: Option<Label>, + pub while_token: Token![while], + pub cond: Box<Expr>, + pub body: Block, + } +} + +ast_struct! { + /// A yield expression: `yield expr`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct ExprYield #full { + pub attrs: Vec<Attribute>, + pub yield_token: Token![yield], + pub expr: Option<Box<Expr>>, + } +} + +impl Expr { + /// An unspecified invalid expression. + /// + /// ``` + /// use quote::ToTokens; + /// use std::mem; + /// use syn::{parse_quote, Expr}; + /// + /// fn unparenthesize(e: &mut Expr) { + /// while let Expr::Paren(paren) = e { + /// *e = mem::replace(&mut *paren.expr, Expr::PLACEHOLDER); + /// } + /// } + /// + /// fn main() { + /// let mut e: Expr = parse_quote! { ((1 + 1)) }; + /// unparenthesize(&mut e); + /// assert_eq!("1 + 1", e.to_token_stream().to_string()); + /// } + /// ``` + pub const PLACEHOLDER: Self = Expr::Path(ExprPath { + attrs: Vec::new(), + qself: None, + path: Path { + leading_colon: None, + segments: Punctuated::new(), + }, + }); + + /// An alternative to the primary `Expr::parse` parser (from the [`Parse`] + /// trait) for ambiguous syntactic positions in which a trailing brace + /// should not be taken as part of the expression. + /// + /// [`Parse`]: crate::parse::Parse + /// + /// Rust grammar has an ambiguity where braces sometimes turn a path + /// expression into a struct initialization and sometimes do not. In the + /// following code, the expression `S {}` is one expression. Presumably + /// there is an empty struct `struct S {}` defined somewhere which it is + /// instantiating. + /// + /// ``` + /// # struct S; + /// # impl std::ops::Deref for S { + /// # type Target = bool; + /// # fn deref(&self) -> &Self::Target { + /// # &true + /// # } + /// # } + /// let _ = *S {}; + /// + /// // parsed by rustc as: `*(S {})` + /// ``` + /// + /// We would want to parse the above using `Expr::parse` after the `=` + /// token. + /// + /// But in the following, `S {}` is *not* a struct init expression. + /// + /// ``` + /// # const S: &bool = &true; + /// if *S {} {} + /// + /// // parsed by rustc as: + /// // + /// // if (*S) { + /// // /* empty block */ + /// // } + /// // { + /// // /* another empty block */ + /// // } + /// ``` + /// + /// For that reason we would want to parse if-conditions using + /// `Expr::parse_without_eager_brace` after the `if` token. Same for similar + /// syntactic positions such as the condition expr after a `while` token or + /// the expr at the top of a `match`. + /// + /// The Rust grammar's choices around which way this ambiguity is resolved + /// at various syntactic positions is fairly arbitrary. Really either parse + /// behavior could work in most positions, and language designers just + /// decide each case based on which is more likely to be what the programmer + /// had in mind most of the time. + /// + /// ``` + /// # struct S; + /// # fn doc() -> S { + /// if return S {} {} + /// # unreachable!() + /// # } + /// + /// // parsed by rustc as: + /// // + /// // if (return (S {})) { + /// // } + /// // + /// // but could equally well have been this other arbitrary choice: + /// // + /// // if (return S) { + /// // } + /// // {} + /// ``` + /// + /// Note the grammar ambiguity on trailing braces is distinct from + /// precedence and is not captured by assigning a precedence level to the + /// braced struct init expr in relation to other operators. This can be + /// illustrated by `return 0..S {}` vs `match 0..S {}`. The former parses as + /// `return (0..(S {}))` implying tighter precedence for struct init than + /// `..`, while the latter parses as `match (0..S) {}` implying tighter + /// precedence for `..` than struct init, a contradiction. + #[cfg(all(feature = "full", feature = "parsing"))] + #[cfg_attr(docsrs, doc(cfg(all(feature = "full", feature = "parsing"))))] + pub fn parse_without_eager_brace(input: ParseStream) -> Result<Expr> { + parsing::ambiguous_expr(input, parsing::AllowStruct(false)) + } + + /// An alternative to the primary `Expr::parse` parser (from the [`Parse`] + /// trait) for syntactic positions in which expression boundaries are placed + /// more eagerly than done by the typical expression grammar. This includes + /// expressions at the head of a statement or in the right-hand side of a + /// `match` arm. + /// + /// [`Parse`]: crate::parse::Parse + /// + /// Compare the following cases: + /// + /// 1. + /// ``` + /// # let result = (); + /// # let guard = false; + /// # let cond = true; + /// # let f = true; + /// # let g = f; + /// # + /// let _ = match result { + /// () if guard => if cond { f } else { g } + /// () => false, + /// }; + /// ``` + /// + /// 2. + /// ``` + /// # let cond = true; + /// # let f = (); + /// # let g = f; + /// # + /// let _ = || { + /// if cond { f } else { g } + /// () + /// }; + /// ``` + /// + /// 3. + /// ``` + /// # let cond = true; + /// # let f = || (); + /// # let g = f; + /// # + /// let _ = [if cond { f } else { g } ()]; + /// ``` + /// + /// The same sequence of tokens `if cond { f } else { g } ()` appears in + /// expression position 3 times. The first two syntactic positions use eager + /// placement of expression boundaries, and parse as `Expr::If`, with the + /// adjacent `()` becoming `Pat::Tuple` or `Expr::Tuple`. In contrast, the + /// third case uses standard expression boundaries and parses as + /// `Expr::Call`. + /// + /// As with [`parse_without_eager_brace`], this ambiguity in the Rust + /// grammar is independent of precedence. + /// + /// [`parse_without_eager_brace`]: Self::parse_without_eager_brace + #[cfg(all(feature = "full", feature = "parsing"))] + #[cfg_attr(docsrs, doc(cfg(all(feature = "full", feature = "parsing"))))] + pub fn parse_with_earlier_boundary_rule(input: ParseStream) -> Result<Expr> { + parsing::parse_with_earlier_boundary_rule(input) + } + + /// Returns whether the next token in the parse stream is one that might + /// possibly form the beginning of an expr. + /// + /// This classification is a load-bearing part of the grammar of some Rust + /// expressions, notably `return` and `break`. For example `return < …` will + /// never parse `<` as a binary operator regardless of what comes after, + /// because `<` is a legal starting token for an expression and so it's + /// required to be continued as a return value, such as `return <Struct as + /// Trait>::CONST`. Meanwhile `return > …` treats the `>` as a binary + /// operator because it cannot be a starting token for any Rust expression. + #[cfg(feature = "parsing")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + pub fn peek(input: ParseStream) -> bool { + input.peek(Ident::peek_any) && !input.peek(Token![as]) // value name or keyword + || input.peek(token::Paren) // tuple + || input.peek(token::Bracket) // array + || input.peek(token::Brace) // block + || input.peek(Lit) // literal + || input.peek(Token![!]) && !input.peek(Token![!=]) // operator not + || input.peek(Token![-]) && !input.peek(Token![-=]) && !input.peek(Token![->]) // unary minus + || input.peek(Token![*]) && !input.peek(Token![*=]) // dereference + || input.peek(Token![|]) && !input.peek(Token![|=]) // closure + || input.peek(Token![&]) && !input.peek(Token![&=]) // reference + || input.peek(Token![..]) // range + || input.peek(Token![<]) && !input.peek(Token![<=]) && !input.peek(Token![<<=]) // associated path + || input.peek(Token![::]) // absolute path + || input.peek(Lifetime) // labeled loop + || input.peek(Token![#]) // expression attributes + } + + #[cfg(all(feature = "parsing", feature = "full"))] + pub(crate) fn replace_attrs(&mut self, new: Vec<Attribute>) -> Vec<Attribute> { + match self { + Expr::Array(ExprArray { attrs, .. }) + | Expr::Assign(ExprAssign { attrs, .. }) + | Expr::Async(ExprAsync { attrs, .. }) + | Expr::Await(ExprAwait { attrs, .. }) + | Expr::Binary(ExprBinary { attrs, .. }) + | Expr::Block(ExprBlock { attrs, .. }) + | Expr::Break(ExprBreak { attrs, .. }) + | Expr::Call(ExprCall { attrs, .. }) + | Expr::Cast(ExprCast { attrs, .. }) + | Expr::Closure(ExprClosure { 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::Let(ExprLet { 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::Range(ExprRange { attrs, .. }) + | Expr::RawAddr(ExprRawAddr { attrs, .. }) + | Expr::Reference(ExprReference { attrs, .. }) + | Expr::Repeat(ExprRepeat { attrs, .. }) + | Expr::Return(ExprReturn { attrs, .. }) + | Expr::Struct(ExprStruct { attrs, .. }) + | Expr::Try(ExprTry { attrs, .. }) + | Expr::TryBlock(ExprTryBlock { attrs, .. }) + | Expr::Tuple(ExprTuple { attrs, .. }) + | Expr::Unary(ExprUnary { attrs, .. }) + | Expr::Unsafe(ExprUnsafe { attrs, .. }) + | Expr::While(ExprWhile { attrs, .. }) + | Expr::Yield(ExprYield { attrs, .. }) => mem::replace(attrs, new), + Expr::Verbatim(_) => Vec::new(), + } + } +} + +ast_enum! { + /// A struct or tuple struct field accessed in a struct literal or field + /// expression. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub enum Member { + /// A named field like `self.x`. + Named(Ident), + /// An unnamed field like `self.0`. + Unnamed(Index), + } +} + +impl From<Ident> for Member { + fn from(ident: Ident) -> Member { + Member::Named(ident) + } +} + +impl From<Index> for Member { + fn from(index: Index) -> Member { + Member::Unnamed(index) + } +} + +impl From<usize> for Member { + fn from(index: usize) -> Member { + Member::Unnamed(Index::from(index)) + } +} + +impl Eq for Member {} + +impl PartialEq for Member { + fn eq(&self, other: &Self) -> bool { + match (self, other) { + (Member::Named(this), Member::Named(other)) => this == other, + (Member::Unnamed(this), Member::Unnamed(other)) => this == other, + _ => false, + } + } +} + +impl Hash for Member { + fn hash<H: Hasher>(&self, state: &mut H) { + match self { + Member::Named(m) => m.hash(state), + Member::Unnamed(m) => m.hash(state), + } + } +} + +#[cfg(feature = "printing")] +impl IdentFragment for Member { + fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + match self { + Member::Named(m) => Display::fmt(m, formatter), + Member::Unnamed(m) => Display::fmt(&m.index, formatter), + } + } + + fn span(&self) -> Option<Span> { + match self { + Member::Named(m) => Some(m.span()), + Member::Unnamed(m) => Some(m.span), + } + } +} + +#[cfg(any(feature = "parsing", feature = "printing"))] +impl Member { + pub(crate) fn is_named(&self) -> bool { + match self { + Member::Named(_) => true, + Member::Unnamed(_) => false, + } + } +} + +ast_struct! { + /// The index of an unnamed tuple struct field. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct Index { + pub index: u32, + pub span: Span, + } +} + +impl From<usize> for Index { + fn from(index: usize) -> Index { + assert!(index < u32::MAX as usize); + Index { + index: index as u32, + span: Span::call_site(), + } + } +} + +impl Eq for Index {} + +impl PartialEq for Index { + fn eq(&self, other: &Self) -> bool { + self.index == other.index + } +} + +impl Hash for Index { + fn hash<H: Hasher>(&self, state: &mut H) { + self.index.hash(state); + } +} + +#[cfg(feature = "printing")] +impl IdentFragment for Index { + fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + Display::fmt(&self.index, formatter) + } + + fn span(&self) -> Option<Span> { + Some(self.span) + } +} + +ast_struct! { + /// A field-value pair in a struct literal. + #[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct FieldValue { + pub attrs: Vec<Attribute>, + pub member: Member, + + /// The colon in `Struct { x: x }`. If written in shorthand like + /// `Struct { x }`, there is no colon. + pub colon_token: Option<Token![:]>, + + pub expr: Expr, + } +} + +#[cfg(feature = "full")] +ast_struct! { + /// A lifetime labeling a `for`, `while`, or `loop`. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct Label { + pub name: Lifetime, + pub colon_token: Token![:], + } +} + +#[cfg(feature = "full")] +ast_struct! { + /// One arm of a `match` expression: `0..=10 => { return true; }`. + /// + /// As in: + /// + /// ``` + /// # fn f() -> bool { + /// # let n = 0; + /// match n { + /// 0..=10 => { + /// return true; + /// } + /// // ... + /// # _ => {} + /// } + /// # false + /// # } + /// ``` + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub struct Arm { + pub attrs: Vec<Attribute>, + pub pat: Pat, + pub guard: Option<(Token![if], Box<Expr>)>, + pub fat_arrow_token: Token![=>], + pub body: Box<Expr>, + pub comma: Option<Token![,]>, + } +} + +#[cfg(feature = "full")] +ast_enum! { + /// Limit types of a range, inclusive or exclusive. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub enum RangeLimits { + /// Inclusive at the beginning, exclusive at the end. + HalfOpen(Token![..]), + /// Inclusive at the beginning and end. + Closed(Token![..=]), + } +} + +#[cfg(feature = "full")] +ast_enum! { + /// Mutability of a raw pointer (`*const T`, `*mut T`), in which non-mutable + /// isn't the implicit default. + #[cfg_attr(docsrs, doc(cfg(feature = "full")))] + pub enum PointerMutability { + Const(Token![const]), + Mut(Token![mut]), + } +} + +#[cfg(feature = "parsing")] +pub(crate) mod parsing { + #[cfg(feature = "full")] + use crate::attr; + use crate::attr::Attribute; + #[cfg(feature = "full")] + use crate::classify; + use crate::error::{Error, Result}; + #[cfg(feature = "full")] + use crate::expr::{ + Arm, ExprArray, ExprAssign, ExprAsync, ExprAwait, ExprBlock, ExprBreak, ExprClosure, + ExprConst, ExprContinue, ExprForLoop, ExprIf, ExprInfer, ExprLet, ExprLoop, ExprMatch, + ExprRange, ExprRawAddr, ExprRepeat, ExprReturn, ExprTry, ExprTryBlock, ExprUnsafe, + ExprWhile, ExprYield, Label, PointerMutability, RangeLimits, + }; + use crate::expr::{ + Expr, ExprBinary, ExprCall, ExprCast, ExprField, ExprGroup, ExprIndex, ExprLit, ExprMacro, + ExprMethodCall, ExprParen, ExprPath, ExprReference, ExprStruct, ExprTuple, ExprUnary, + FieldValue, Index, Member, + }; + #[cfg(feature = "full")] + use crate::generics::{self, BoundLifetimes}; + use crate::ident::Ident; + #[cfg(feature = "full")] + use crate::lifetime::Lifetime; + use crate::lit::{Lit, LitFloat, LitInt}; + use crate::mac::{self, Macro}; + use crate::op::BinOp; + use crate::parse::discouraged::Speculative as _; + #[cfg(feature = "full")] + use crate::parse::ParseBuffer; + use crate::parse::{Parse, ParseStream}; + #[cfg(feature = "full")] + use crate::pat::{Pat, PatType}; + use crate::path::{self, AngleBracketedGenericArguments, Path, QSelf}; + use crate::precedence::Precedence; + use crate::punctuated::Punctuated; + #[cfg(feature = "full")] + use crate::stmt::Block; + use crate::token; + use crate::ty; + #[cfg(feature = "full")] + use crate::ty::{ReturnType, Type}; + use crate::verbatim; + #[cfg(feature = "full")] + use proc_macro2::{Span, TokenStream}; + use std::mem; + + // When we're parsing expressions which occur before blocks, like in an if + // statement's condition, we cannot parse a struct literal. + // + // Struct literals are ambiguous in certain positions + // https://github.com/rust-lang/rfcs/pull/92 + #[cfg(feature = "full")] + pub(super) struct AllowStruct(pub bool); + + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for Expr { + fn parse(input: ParseStream) -> Result<Self> { + ambiguous_expr( + input, + #[cfg(feature = "full")] + AllowStruct(true), + ) + } + } + + #[cfg(feature = "full")] + pub(super) fn parse_with_earlier_boundary_rule(input: ParseStream) -> Result<Expr> { + let mut attrs = input.call(expr_attrs)?; + let mut expr = if input.peek(token::Group) { + let allow_struct = AllowStruct(true); + let atom = expr_group(input, allow_struct)?; + if continue_parsing_early(&atom) { + trailer_helper(input, atom)? + } else { + atom + } + } else if input.peek(Token![if]) { + Expr::If(input.parse()?) + } else if input.peek(Token![while]) { + Expr::While(input.parse()?) + } else if input.peek(Token![for]) + && !generics::parsing::choose_generics_over_qpath_after_keyword(input) + { + Expr::ForLoop(input.parse()?) + } else if input.peek(Token![loop]) { + Expr::Loop(input.parse()?) + } else if input.peek(Token![match]) { + Expr::Match(input.parse()?) + } else if input.peek(Token![try]) && input.peek2(token::Brace) { + Expr::TryBlock(input.parse()?) + } else if input.peek(Token![unsafe]) { + Expr::Unsafe(input.parse()?) + } else if input.peek(Token![const]) && input.peek2(token::Brace) { + Expr::Const(input.parse()?) + } else if input.peek(token::Brace) { + Expr::Block(input.parse()?) + } else if input.peek(Lifetime) { + atom_labeled(input)? + } else { + let allow_struct = AllowStruct(true); + unary_expr(input, allow_struct)? + }; + + if continue_parsing_early(&expr) { + attrs.extend(expr.replace_attrs(Vec::new())); + expr.replace_attrs(attrs); + + let allow_struct = AllowStruct(true); + return parse_expr(input, expr, allow_struct, Precedence::MIN); + } + + if input.peek(Token![.]) && !input.peek(Token![..]) || input.peek(Token![?]) { + expr = trailer_helper(input, expr)?; + + attrs.extend(expr.replace_attrs(Vec::new())); + expr.replace_attrs(attrs); + + let allow_struct = AllowStruct(true); + return parse_expr(input, expr, allow_struct, Precedence::MIN); + } + + attrs.extend(expr.replace_attrs(Vec::new())); + expr.replace_attrs(attrs); + Ok(expr) + } + + #[cfg(feature = "full")] + impl Copy for AllowStruct {} + + #[cfg(feature = "full")] + impl Clone for AllowStruct { + fn clone(&self) -> Self { + *self + } + } + + #[cfg(feature = "full")] + fn parse_expr( + input: ParseStream, + mut lhs: Expr, + allow_struct: AllowStruct, + base: Precedence, + ) -> Result<Expr> { + loop { + let ahead = input.fork(); + if let Expr::Range(_) = lhs { + // A range cannot be the left-hand side of another binary operator. + break; + } else if let Ok(op) = ahead.parse::<BinOp>() { + let precedence = Precedence::of_binop(&op); + if precedence < base { + break; + } + if precedence == Precedence::Assign { + if let Expr::Range(_) = lhs { + break; + } + } + if precedence == Precedence::Compare { + if let Expr::Binary(lhs) = &lhs { + if Precedence::of_binop(&lhs.op) == Precedence::Compare { + return Err(input.error("comparison operators cannot be chained")); + } + } + } + input.advance_to(&ahead); + let right = parse_binop_rhs(input, allow_struct, precedence)?; + lhs = Expr::Binary(ExprBinary { + attrs: Vec::new(), + left: Box::new(lhs), + op, + right, + }); + } else if Precedence::Assign >= base + && input.peek(Token![=]) + && !input.peek(Token![=>]) + && match lhs { + Expr::Range(_) => false, + _ => true, + } + { + let eq_token: Token![=] = input.parse()?; + let right = parse_binop_rhs(input, allow_struct, Precedence::Assign)?; + lhs = Expr::Assign(ExprAssign { + attrs: Vec::new(), + left: Box::new(lhs), + eq_token, + right, + }); + } else if Precedence::Range >= base && input.peek(Token![..]) { + let limits: RangeLimits = input.parse()?; + let end = parse_range_end(input, &limits, allow_struct)?; + lhs = Expr::Range(ExprRange { + attrs: Vec::new(), + start: Some(Box::new(lhs)), + limits, + end, + }); + } else if Precedence::Cast >= base && input.peek(Token![as]) { + let as_token: Token![as] = input.parse()?; + let allow_plus = false; + let allow_group_generic = false; + let ty = ty::parsing::ambig_ty(input, allow_plus, allow_group_generic)?; + check_cast(input)?; + lhs = Expr::Cast(ExprCast { + attrs: Vec::new(), + expr: Box::new(lhs), + as_token, + ty: Box::new(ty), + }); + } else { + break; + } + } + Ok(lhs) + } + + #[cfg(not(feature = "full"))] + fn parse_expr(input: ParseStream, mut lhs: Expr, base: Precedence) -> Result<Expr> { + loop { + let ahead = input.fork(); + if let Ok(op) = ahead.parse::<BinOp>() { + let precedence = Precedence::of_binop(&op); + if precedence < base { + break; + } + if precedence == Precedence::Compare { + if let Expr::Binary(lhs) = &lhs { + if Precedence::of_binop(&lhs.op) == Precedence::Compare { + return Err(input.error("comparison operators cannot be chained")); + } + } + } + input.advance_to(&ahead); + let right = parse_binop_rhs(input, precedence)?; + lhs = Expr::Binary(ExprBinary { + attrs: Vec::new(), + left: Box::new(lhs), + op, + right, + }); + } else if Precedence::Cast >= base && input.peek(Token![as]) { + let as_token: Token![as] = input.parse()?; + let allow_plus = false; + let allow_group_generic = false; + let ty = ty::parsing::ambig_ty(input, allow_plus, allow_group_generic)?; + check_cast(input)?; + lhs = Expr::Cast(ExprCast { + attrs: Vec::new(), + expr: Box::new(lhs), + as_token, + ty: Box::new(ty), + }); + } else { + break; + } + } + Ok(lhs) + } + + fn parse_binop_rhs( + input: ParseStream, + #[cfg(feature = "full")] allow_struct: AllowStruct, + precedence: Precedence, + ) -> Result<Box<Expr>> { + let mut rhs = unary_expr( + input, + #[cfg(feature = "full")] + allow_struct, + )?; + loop { + let next = peek_precedence(input); + if next > precedence || next == precedence && precedence == Precedence::Assign { + let cursor = input.cursor(); + rhs = parse_expr( + input, + rhs, + #[cfg(feature = "full")] + allow_struct, + next, + )?; + if cursor == input.cursor() { + // Bespoke grammar restrictions separate from precedence can + // cause parsing to not advance, such as `..a` being + // disallowed in the left-hand side of binary operators, + // even ones that have lower precedence than `..`. + break; + } + } else { + break; + } + } + Ok(Box::new(rhs)) + } + + fn peek_precedence(input: ParseStream) -> Precedence { + if let Ok(op) = input.fork().parse() { + Precedence::of_binop(&op) + } else if input.peek(Token![=]) && !input.peek(Token![=>]) { + Precedence::Assign + } else if input.peek(Token![..]) { + Precedence::Range + } else if input.peek(Token![as]) { + Precedence::Cast + } else { + Precedence::MIN + } + } + + // Parse an arbitrary expression. + pub(super) fn ambiguous_expr( + input: ParseStream, + #[cfg(feature = "full")] allow_struct: AllowStruct, + ) -> Result<Expr> { + let lhs = unary_expr( + input, + #[cfg(feature = "full")] + allow_struct, + )?; + parse_expr( + input, + lhs, + #[cfg(feature = "full")] + allow_struct, + Precedence::MIN, + ) + } + + #[cfg(feature = "full")] + fn expr_attrs(input: ParseStream) -> Result<Vec<Attribute>> { + let mut attrs = Vec::new(); + while !input.peek(token::Group) && input.peek(Token![#]) { + attrs.push(input.call(attr::parsing::single_parse_outer)?); + } + Ok(attrs) + } + + // <UnOp> <trailer> + // & <trailer> + // &mut <trailer> + // box <trailer> + #[cfg(feature = "full")] + fn unary_expr(input: ParseStream, allow_struct: AllowStruct) -> Result<Expr> { + let begin = input.fork(); + let attrs = input.call(expr_attrs)?; + if input.peek(token::Group) { + return trailer_expr(begin, attrs, input, allow_struct); + } + + if input.peek(Token![&]) { + let and_token: Token![&] = input.parse()?; + let raw: Option<Token![raw]> = if input.peek(Token![raw]) + && (input.peek2(Token![mut]) || input.peek2(Token![const])) + { + Some(input.parse()?) + } else { + None + }; + let mutability: Option<Token![mut]> = input.parse()?; + let const_token: Option<Token![const]> = if raw.is_some() && mutability.is_none() { + Some(input.parse()?) + } else { + None + }; + let expr = Box::new(unary_expr(input, allow_struct)?); + if let Some(raw) = raw { + Ok(Expr::RawAddr(ExprRawAddr { + attrs, + and_token, + raw, + mutability: match mutability { + Some(mut_token) => PointerMutability::Mut(mut_token), + None => PointerMutability::Const(const_token.unwrap()), + }, + expr, + })) + } else { + Ok(Expr::Reference(ExprReference { + attrs, + and_token, + mutability, + expr, + })) + } + } else if input.peek(Token![*]) || input.peek(Token![!]) || input.peek(Token![-]) { + expr_unary(input, attrs, allow_struct).map(Expr::Unary) + } else { + trailer_expr(begin, attrs, input, allow_struct) + } + } + + #[cfg(not(feature = "full"))] + fn unary_expr(input: ParseStream) -> Result<Expr> { + if input.peek(Token![&]) { + Ok(Expr::Reference(ExprReference { + attrs: Vec::new(), + and_token: input.parse()?, + mutability: input.parse()?, + expr: Box::new(unary_expr(input)?), + })) + } else if input.peek(Token![*]) || input.peek(Token![!]) || input.peek(Token![-]) { + Ok(Expr::Unary(ExprUnary { + attrs: Vec::new(), + op: input.parse()?, + expr: Box::new(unary_expr(input)?), + })) + } else { + trailer_expr(input) + } + } + + // <atom> (..<args>) ... + // <atom> . <ident> (..<args>) ... + // <atom> . <ident> ... + // <atom> . <lit> ... + // <atom> [ <expr> ] ... + // <atom> ? ... + #[cfg(feature = "full")] + fn trailer_expr( + begin: ParseBuffer, + mut attrs: Vec<Attribute>, + input: ParseStream, + allow_struct: AllowStruct, + ) -> Result<Expr> { + let atom = atom_expr(input, allow_struct)?; + let mut e = trailer_helper(input, atom)?; + + if let Expr::Verbatim(tokens) = &mut e { + *tokens = verbatim::between(&begin, input); + } else if !attrs.is_empty() { + if let Expr::Range(range) = e { + let spans: &[Span] = match &range.limits { + RangeLimits::HalfOpen(limits) => &limits.spans, + RangeLimits::Closed(limits) => &limits.spans, + }; + return Err(crate::error::new2( + spans[0], + *spans.last().unwrap(), + "attributes are not allowed on range expressions starting with `..`", + )); + } + let inner_attrs = e.replace_attrs(Vec::new()); + attrs.extend(inner_attrs); + e.replace_attrs(attrs); + } + + Ok(e) + } + + #[cfg(feature = "full")] + fn trailer_helper(input: ParseStream, mut e: Expr) -> Result<Expr> { + loop { + if input.peek(token::Paren) { + let content; + e = Expr::Call(ExprCall { + attrs: Vec::new(), + func: Box::new(e), + paren_token: parenthesized!(content in input), + args: content.parse_terminated(Expr::parse, Token![,])?, + }); + } else if input.peek(Token![.]) + && !input.peek(Token![..]) + && match e { + Expr::Range(_) => false, + _ => true, + } + { + let mut dot_token: Token![.] = input.parse()?; + + let float_token: Option<LitFloat> = input.parse()?; + if let Some(float_token) = float_token { + if multi_index(&mut e, &mut dot_token, float_token)? { + continue; + } + } + + let await_token: Option<Token![await]> = input.parse()?; + if let Some(await_token) = await_token { + e = Expr::Await(ExprAwait { + attrs: Vec::new(), + base: Box::new(e), + dot_token, + await_token, + }); + continue; + } + + let member: Member = input.parse()?; + let turbofish = if member.is_named() && input.peek(Token![::]) { + Some(AngleBracketedGenericArguments::parse_turbofish(input)?) + } else { + None + }; + + if turbofish.is_some() || input.peek(token::Paren) { + if let Member::Named(method) = member { + let content; + e = Expr::MethodCall(ExprMethodCall { + attrs: Vec::new(), + receiver: Box::new(e), + dot_token, + method, + turbofish, + paren_token: parenthesized!(content in input), + args: content.parse_terminated(Expr::parse, Token![,])?, + }); + continue; + } + } + + e = Expr::Field(ExprField { + attrs: Vec::new(), + base: Box::new(e), + dot_token, + member, + }); + } else if input.peek(token::Bracket) { + let content; + e = Expr::Index(ExprIndex { + attrs: Vec::new(), + expr: Box::new(e), + bracket_token: bracketed!(content in input), + index: content.parse()?, + }); + } else if input.peek(Token![?]) + && match e { + Expr::Range(_) => false, + _ => true, + } + { + e = Expr::Try(ExprTry { + attrs: Vec::new(), + expr: Box::new(e), + question_token: input.parse()?, + }); + } else { + break; + } + } + Ok(e) + } + + #[cfg(not(feature = "full"))] + fn trailer_expr(input: ParseStream) -> Result<Expr> { + let mut e = atom_expr(input)?; + + loop { + if input.peek(token::Paren) { + let content; + e = Expr::Call(ExprCall { + attrs: Vec::new(), + func: Box::new(e), + paren_token: parenthesized!(content in input), + args: content.parse_terminated(Expr::parse, Token![,])?, + }); + } else if input.peek(Token![.]) + && !input.peek(Token![..]) + && !input.peek2(Token![await]) + { + let mut dot_token: Token![.] = input.parse()?; + + let float_token: Option<LitFloat> = input.parse()?; + if let Some(float_token) = float_token { + if multi_index(&mut e, &mut dot_token, float_token)? { + continue; + } + } + + let member: Member = input.parse()?; + let turbofish = if member.is_named() && input.peek(Token![::]) { + let colon2_token: Token![::] = input.parse()?; + let turbofish = + AngleBracketedGenericArguments::do_parse(Some(colon2_token), input)?; + Some(turbofish) + } else { + None + }; + + if turbofish.is_some() || input.peek(token::Paren) { + if let Member::Named(method) = member { + let content; + e = Expr::MethodCall(ExprMethodCall { + attrs: Vec::new(), + receiver: Box::new(e), + dot_token, + method, + turbofish, + paren_token: parenthesized!(content in input), + args: content.parse_terminated(Expr::parse, Token![,])?, + }); + continue; + } + } + + e = Expr::Field(ExprField { + attrs: Vec::new(), + base: Box::new(e), + dot_token, + member, + }); + } else if input.peek(token::Bracket) { + let content; + e = Expr::Index(ExprIndex { + attrs: Vec::new(), + expr: Box::new(e), + bracket_token: bracketed!(content in input), + index: content.parse()?, + }); + } else { + break; + } + } + + Ok(e) + } + + // Parse all atomic expressions which don't have to worry about precedence + // interactions, as they are fully contained. + #[cfg(feature = "full")] + fn atom_expr(input: ParseStream, allow_struct: AllowStruct) -> Result<Expr> { + if input.peek(token::Group) { + expr_group(input, allow_struct) + } else if input.peek(Lit) { + input.parse().map(Expr::Lit) + } else if input.peek(Token![async]) + && (input.peek2(token::Brace) || input.peek2(Token![move]) && input.peek3(token::Brace)) + { + input.parse().map(Expr::Async) + } else if input.peek(Token![try]) && input.peek2(token::Brace) { + input.parse().map(Expr::TryBlock) + } else if input.peek(Token![|]) + || input.peek(Token![move]) + || input.peek(Token![for]) + && generics::parsing::choose_generics_over_qpath_after_keyword(input) + || input.peek(Token![const]) && !input.peek2(token::Brace) + || input.peek(Token![static]) + || input.peek(Token![async]) && (input.peek2(Token![|]) || input.peek2(Token![move])) + { + expr_closure(input, allow_struct).map(Expr::Closure) + } else if token::parsing::peek_keyword(input.cursor(), "builtin") && input.peek2(Token![#]) + { + expr_builtin(input) + } else if input.peek(Ident) + || input.peek(Token![::]) + || input.peek(Token![<]) + || input.peek(Token![self]) + || input.peek(Token![Self]) + || input.peek(Token![super]) + || input.peek(Token![crate]) + || input.peek(Token![try]) && (input.peek2(Token![!]) || input.peek2(Token![::])) + { + path_or_macro_or_struct(input, allow_struct) + } else if input.peek(token::Paren) { + paren_or_tuple(input) + } else if input.peek(Token![break]) { + expr_break(input, allow_struct).map(Expr::Break) + } else if input.peek(Token![continue]) { + input.parse().map(Expr::Continue) + } else if input.peek(Token![return]) { + input.parse().map(Expr::Return) + } else if input.peek(Token![become]) { + expr_become(input) + } else if input.peek(token::Bracket) { + array_or_repeat(input) + } else if input.peek(Token![let]) { + expr_let(input, allow_struct).map(Expr::Let) + } else if input.peek(Token![if]) { + input.parse().map(Expr::If) + } else if input.peek(Token![while]) { + input.parse().map(Expr::While) + } else if input.peek(Token![for]) { + input.parse().map(Expr::ForLoop) + } else if input.peek(Token![loop]) { + input.parse().map(Expr::Loop) + } else if input.peek(Token![match]) { + input.parse().map(Expr::Match) + } else if input.peek(Token![yield]) { + input.parse().map(Expr::Yield) + } else if input.peek(Token![unsafe]) { + input.parse().map(Expr::Unsafe) + } else if input.peek(Token![const]) { + input.parse().map(Expr::Const) + } else if input.peek(token::Brace) { + input.parse().map(Expr::Block) + } else if input.peek(Token![..]) { + expr_range(input, allow_struct).map(Expr::Range) + } else if input.peek(Token![_]) { + input.parse().map(Expr::Infer) + } else if input.peek(Lifetime) { + atom_labeled(input) + } else { + Err(input.error("expected an expression")) + } + } + + #[cfg(feature = "full")] + fn atom_labeled(input: ParseStream) -> Result<Expr> { + let the_label: Label = input.parse()?; + let mut expr = if input.peek(Token![while]) { + Expr::While(input.parse()?) + } else if input.peek(Token![for]) { + Expr::ForLoop(input.parse()?) + } else if input.peek(Token![loop]) { + Expr::Loop(input.parse()?) + } else if input.peek(token::Brace) { + Expr::Block(input.parse()?) + } else { + return Err(input.error("expected loop or block expression")); + }; + match &mut expr { + Expr::While(ExprWhile { label, .. }) + | Expr::ForLoop(ExprForLoop { label, .. }) + | Expr::Loop(ExprLoop { label, .. }) + | Expr::Block(ExprBlock { label, .. }) => *label = Some(the_label), + _ => unreachable!(), + } + Ok(expr) + } + + #[cfg(not(feature = "full"))] + fn atom_expr(input: ParseStream) -> Result<Expr> { + if input.peek(token::Group) { + expr_group(input) + } else if input.peek(Lit) { + input.parse().map(Expr::Lit) + } else if input.peek(token::Paren) { + paren_or_tuple(input) + } else if input.peek(Ident) + || input.peek(Token![::]) + || input.peek(Token![<]) + || input.peek(Token![self]) + || input.peek(Token![Self]) + || input.peek(Token![super]) + || input.peek(Token![crate]) + { + path_or_macro_or_struct(input) + } else if input.is_empty() { + Err(input.error("expected an expression")) + } else { + if input.peek(token::Brace) { + let scan = input.fork(); + let content; + braced!(content in scan); + if content.parse::<Expr>().is_ok() && content.is_empty() { + let expr_block = verbatim::between(input, &scan); + input.advance_to(&scan); + return Ok(Expr::Verbatim(expr_block)); + } + } + Err(input.error("unsupported expression; enable syn's features=[\"full\"]")) + } + } + + #[cfg(feature = "full")] + fn expr_builtin(input: ParseStream) -> Result<Expr> { + let begin = input.fork(); + + token::parsing::keyword(input, "builtin")?; + input.parse::<Token![#]>()?; + input.parse::<Ident>()?; + + let args; + parenthesized!(args in input); + args.parse::<TokenStream>()?; + + Ok(Expr::Verbatim(verbatim::between(&begin, input))) + } + + fn path_or_macro_or_struct( + input: ParseStream, + #[cfg(feature = "full")] allow_struct: AllowStruct, + ) -> Result<Expr> { + let expr_style = true; + let (qself, path) = path::parsing::qpath(input, expr_style)?; + rest_of_path_or_macro_or_struct( + qself, + path, + input, + #[cfg(feature = "full")] + allow_struct, + ) + } + + fn rest_of_path_or_macro_or_struct( + qself: Option<QSelf>, + path: Path, + input: ParseStream, + #[cfg(feature = "full")] allow_struct: AllowStruct, + ) -> Result<Expr> { + if qself.is_none() + && input.peek(Token![!]) + && !input.peek(Token![!=]) + && path.is_mod_style() + { + let bang_token: Token![!] = input.parse()?; + let (delimiter, tokens) = mac::parse_delimiter(input)?; + return Ok(Expr::Macro(ExprMacro { + attrs: Vec::new(), + mac: Macro { + path, + bang_token, + delimiter, + tokens, + }, + })); + } + + #[cfg(not(feature = "full"))] + let allow_struct = (true,); + if allow_struct.0 && input.peek(token::Brace) { + return expr_struct_helper(input, qself, path).map(Expr::Struct); + } + + Ok(Expr::Path(ExprPath { + attrs: Vec::new(), + qself, + path, + })) + } + + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprMacro { + fn parse(input: ParseStream) -> Result<Self> { + Ok(ExprMacro { + attrs: Vec::new(), + mac: input.parse()?, + }) + } + } + + fn paren_or_tuple(input: ParseStream) -> Result<Expr> { + let content; + let paren_token = parenthesized!(content in input); + if content.is_empty() { + return Ok(Expr::Tuple(ExprTuple { + attrs: Vec::new(), + paren_token, + elems: Punctuated::new(), + })); + } + + let first: Expr = content.parse()?; + if content.is_empty() { + return Ok(Expr::Paren(ExprParen { + attrs: Vec::new(), + paren_token, + expr: Box::new(first), + })); + } + + let mut elems = Punctuated::new(); + elems.push_value(first); + while !content.is_empty() { + let punct = content.parse()?; + elems.push_punct(punct); + if content.is_empty() { + break; + } + let value = content.parse()?; + elems.push_value(value); + } + Ok(Expr::Tuple(ExprTuple { + attrs: Vec::new(), + paren_token, + elems, + })) + } + + #[cfg(feature = "full")] + fn array_or_repeat(input: ParseStream) -> Result<Expr> { + let content; + let bracket_token = bracketed!(content in input); + if content.is_empty() { + return Ok(Expr::Array(ExprArray { + attrs: Vec::new(), + bracket_token, + elems: Punctuated::new(), + })); + } + + let first: Expr = content.parse()?; + if content.is_empty() || content.peek(Token![,]) { + let mut elems = Punctuated::new(); + elems.push_value(first); + while !content.is_empty() { + let punct = content.parse()?; + elems.push_punct(punct); + if content.is_empty() { + break; + } + let value = content.parse()?; + elems.push_value(value); + } + Ok(Expr::Array(ExprArray { + attrs: Vec::new(), + bracket_token, + elems, + })) + } else if content.peek(Token![;]) { + let semi_token: Token![;] = content.parse()?; + let len: Expr = content.parse()?; + Ok(Expr::Repeat(ExprRepeat { + attrs: Vec::new(), + bracket_token, + expr: Box::new(first), + semi_token, + len: Box::new(len), + })) + } else { + Err(content.error("expected `,` or `;`")) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprArray { + fn parse(input: ParseStream) -> Result<Self> { + let content; + let bracket_token = bracketed!(content in input); + let mut elems = Punctuated::new(); + + while !content.is_empty() { + let first: Expr = content.parse()?; + elems.push_value(first); + if content.is_empty() { + break; + } + let punct = content.parse()?; + elems.push_punct(punct); + } + + Ok(ExprArray { + attrs: Vec::new(), + bracket_token, + elems, + }) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprRepeat { + fn parse(input: ParseStream) -> Result<Self> { + let content; + Ok(ExprRepeat { + bracket_token: bracketed!(content in input), + attrs: Vec::new(), + expr: content.parse()?, + semi_token: content.parse()?, + len: content.parse()?, + }) + } + } + + #[cfg(feature = "full")] + fn continue_parsing_early(mut expr: &Expr) -> bool { + while let Expr::Group(group) = expr { + expr = &group.expr; + } + match expr { + Expr::If(_) + | Expr::While(_) + | Expr::ForLoop(_) + | Expr::Loop(_) + | Expr::Match(_) + | Expr::TryBlock(_) + | Expr::Unsafe(_) + | Expr::Const(_) + | Expr::Block(_) => false, + _ => true, + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprLit { + fn parse(input: ParseStream) -> Result<Self> { + Ok(ExprLit { + attrs: Vec::new(), + lit: input.parse()?, + }) + } + } + + fn expr_group( + input: ParseStream, + #[cfg(feature = "full")] allow_struct: AllowStruct, + ) -> Result<Expr> { + let group = crate::group::parse_group(input)?; + let mut inner: Expr = group.content.parse()?; + + match inner { + Expr::Path(mut expr) if expr.attrs.is_empty() => { + let grouped_len = expr.path.segments.len(); + Path::parse_rest(input, &mut expr.path, true)?; + match rest_of_path_or_macro_or_struct( + expr.qself, + expr.path, + input, + #[cfg(feature = "full")] + allow_struct, + )? { + Expr::Path(expr) if expr.path.segments.len() == grouped_len => { + inner = Expr::Path(expr); + } + extended => return Ok(extended), + } + } + _ => {} + } + + Ok(Expr::Group(ExprGroup { + attrs: Vec::new(), + group_token: group.token, + expr: Box::new(inner), + })) + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprParen { + fn parse(input: ParseStream) -> Result<Self> { + let content; + Ok(ExprParen { + attrs: Vec::new(), + paren_token: parenthesized!(content in input), + expr: content.parse()?, + }) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprLet { + fn parse(input: ParseStream) -> Result<Self> { + let allow_struct = AllowStruct(true); + expr_let(input, allow_struct) + } + } + + #[cfg(feature = "full")] + fn expr_let(input: ParseStream, allow_struct: AllowStruct) -> Result<ExprLet> { + Ok(ExprLet { + attrs: Vec::new(), + let_token: input.parse()?, + pat: Box::new(Pat::parse_multi_with_leading_vert(input)?), + eq_token: input.parse()?, + expr: Box::new({ + let lhs = unary_expr(input, allow_struct)?; + parse_expr(input, lhs, allow_struct, Precedence::Compare)? + }), + }) + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprIf { + fn parse(input: ParseStream) -> Result<Self> { + let attrs = input.call(Attribute::parse_outer)?; + + let mut clauses = Vec::new(); + let mut expr; + loop { + let if_token: Token![if] = input.parse()?; + let cond = input.call(Expr::parse_without_eager_brace)?; + let then_branch: Block = input.parse()?; + + expr = ExprIf { + attrs: Vec::new(), + if_token, + cond: Box::new(cond), + then_branch, + else_branch: None, + }; + + if !input.peek(Token![else]) { + break; + } + + let else_token: Token![else] = input.parse()?; + let lookahead = input.lookahead1(); + if lookahead.peek(Token![if]) { + expr.else_branch = Some((else_token, Box::new(Expr::PLACEHOLDER))); + clauses.push(expr); + } else if lookahead.peek(token::Brace) { + expr.else_branch = Some(( + else_token, + Box::new(Expr::Block(ExprBlock { + attrs: Vec::new(), + label: None, + block: input.parse()?, + })), + )); + break; + } else { + return Err(lookahead.error()); + } + } + + while let Some(mut prev) = clauses.pop() { + *prev.else_branch.as_mut().unwrap().1 = Expr::If(expr); + expr = prev; + } + expr.attrs = attrs; + Ok(expr) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprInfer { + fn parse(input: ParseStream) -> Result<Self> { + Ok(ExprInfer { + attrs: input.call(Attribute::parse_outer)?, + underscore_token: input.parse()?, + }) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprForLoop { + fn parse(input: ParseStream) -> Result<Self> { + let mut attrs = input.call(Attribute::parse_outer)?; + let label: Option<Label> = input.parse()?; + let for_token: Token![for] = input.parse()?; + + let pat = Pat::parse_multi_with_leading_vert(input)?; + + let in_token: Token![in] = input.parse()?; + let expr: Expr = input.call(Expr::parse_without_eager_brace)?; + + let content; + let brace_token = braced!(content in input); + attr::parsing::parse_inner(&content, &mut attrs)?; + let stmts = content.call(Block::parse_within)?; + + Ok(ExprForLoop { + attrs, + label, + for_token, + pat: Box::new(pat), + in_token, + expr: Box::new(expr), + body: Block { brace_token, stmts }, + }) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprLoop { + fn parse(input: ParseStream) -> Result<Self> { + let mut attrs = input.call(Attribute::parse_outer)?; + let label: Option<Label> = input.parse()?; + let loop_token: Token![loop] = input.parse()?; + + let content; + let brace_token = braced!(content in input); + attr::parsing::parse_inner(&content, &mut attrs)?; + let stmts = content.call(Block::parse_within)?; + + Ok(ExprLoop { + attrs, + label, + loop_token, + body: Block { brace_token, stmts }, + }) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprMatch { + fn parse(input: ParseStream) -> Result<Self> { + let mut attrs = input.call(Attribute::parse_outer)?; + let match_token: Token![match] = input.parse()?; + let expr = Expr::parse_without_eager_brace(input)?; + + let content; + let brace_token = braced!(content in input); + attr::parsing::parse_inner(&content, &mut attrs)?; + + let arms = Arm::parse_multiple(&content)?; + + Ok(ExprMatch { + attrs, + match_token, + expr: Box::new(expr), + brace_token, + arms, + }) + } + } + + macro_rules! impl_by_parsing_expr { + ( + $( + $expr_type:ty, $variant:ident, $msg:expr, + )* + ) => { + $( + #[cfg(all(feature = "full", feature = "printing"))] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for $expr_type { + fn parse(input: ParseStream) -> Result<Self> { + let mut expr: Expr = input.parse()?; + loop { + match expr { + Expr::$variant(inner) => return Ok(inner), + Expr::Group(next) => expr = *next.expr, + _ => return Err(Error::new_spanned(expr, $msg)), + } + } + } + } + )* + }; + } + + impl_by_parsing_expr! { + ExprAssign, Assign, "expected assignment expression", + ExprAwait, Await, "expected await expression", + ExprBinary, Binary, "expected binary operation", + ExprCall, Call, "expected function call expression", + ExprCast, Cast, "expected cast expression", + ExprField, Field, "expected struct field access", + ExprIndex, Index, "expected indexing expression", + ExprMethodCall, MethodCall, "expected method call expression", + ExprRange, Range, "expected range expression", + ExprTry, Try, "expected try expression", + ExprTuple, Tuple, "expected tuple expression", + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprUnary { + fn parse(input: ParseStream) -> Result<Self> { + let attrs = Vec::new(); + let allow_struct = AllowStruct(true); + expr_unary(input, attrs, allow_struct) + } + } + + #[cfg(feature = "full")] + fn expr_unary( + input: ParseStream, + attrs: Vec<Attribute>, + allow_struct: AllowStruct, + ) -> Result<ExprUnary> { + Ok(ExprUnary { + attrs, + op: input.parse()?, + expr: Box::new(unary_expr(input, allow_struct)?), + }) + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprClosure { + fn parse(input: ParseStream) -> Result<Self> { + let allow_struct = AllowStruct(true); + expr_closure(input, allow_struct) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprRawAddr { + fn parse(input: ParseStream) -> Result<Self> { + let allow_struct = AllowStruct(true); + Ok(ExprRawAddr { + attrs: Vec::new(), + and_token: input.parse()?, + raw: input.parse()?, + mutability: input.parse()?, + expr: Box::new(unary_expr(input, allow_struct)?), + }) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprReference { + fn parse(input: ParseStream) -> Result<Self> { + let allow_struct = AllowStruct(true); + Ok(ExprReference { + attrs: Vec::new(), + and_token: input.parse()?, + mutability: input.parse()?, + expr: Box::new(unary_expr(input, allow_struct)?), + }) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprBreak { + fn parse(input: ParseStream) -> Result<Self> { + let allow_struct = AllowStruct(true); + expr_break(input, allow_struct) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprReturn { + fn parse(input: ParseStream) -> Result<Self> { + Ok(ExprReturn { + attrs: Vec::new(), + return_token: input.parse()?, + expr: { + if Expr::peek(input) { + Some(input.parse()?) + } else { + None + } + }, + }) + } + } + + #[cfg(feature = "full")] + fn expr_become(input: ParseStream) -> Result<Expr> { + let begin = input.fork(); + input.parse::<Token![become]>()?; + input.parse::<Expr>()?; + Ok(Expr::Verbatim(verbatim::between(&begin, input))) + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprTryBlock { + fn parse(input: ParseStream) -> Result<Self> { + Ok(ExprTryBlock { + attrs: Vec::new(), + try_token: input.parse()?, + block: input.parse()?, + }) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprYield { + fn parse(input: ParseStream) -> Result<Self> { + Ok(ExprYield { + attrs: Vec::new(), + yield_token: input.parse()?, + expr: { + if Expr::peek(input) { + Some(input.parse()?) + } else { + None + } + }, + }) + } + } + + #[cfg(feature = "full")] + fn expr_closure(input: ParseStream, allow_struct: AllowStruct) -> Result<ExprClosure> { + let lifetimes: Option<BoundLifetimes> = input.parse()?; + let constness: Option<Token![const]> = input.parse()?; + let movability: Option<Token![static]> = input.parse()?; + let asyncness: Option<Token![async]> = input.parse()?; + let capture: Option<Token![move]> = input.parse()?; + let or1_token: Token![|] = input.parse()?; + + let mut inputs = Punctuated::new(); + loop { + if input.peek(Token![|]) { + break; + } + let value = closure_arg(input)?; + inputs.push_value(value); + if input.peek(Token![|]) { + break; + } + let punct: Token![,] = input.parse()?; + inputs.push_punct(punct); + } + + let or2_token: Token![|] = input.parse()?; + + let (output, body) = if input.peek(Token![->]) { + let arrow_token: Token![->] = input.parse()?; + let ty: Type = input.parse()?; + let body: Block = input.parse()?; + let output = ReturnType::Type(arrow_token, Box::new(ty)); + let block = Expr::Block(ExprBlock { + attrs: Vec::new(), + label: None, + block: body, + }); + (output, block) + } else { + let body = ambiguous_expr(input, allow_struct)?; + (ReturnType::Default, body) + }; + + Ok(ExprClosure { + attrs: Vec::new(), + lifetimes, + constness, + movability, + asyncness, + capture, + or1_token, + inputs, + or2_token, + output, + body: Box::new(body), + }) + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprAsync { + fn parse(input: ParseStream) -> Result<Self> { + Ok(ExprAsync { + attrs: Vec::new(), + async_token: input.parse()?, + capture: input.parse()?, + block: input.parse()?, + }) + } + } + + #[cfg(feature = "full")] + fn closure_arg(input: ParseStream) -> Result<Pat> { + let attrs = input.call(Attribute::parse_outer)?; + let mut pat = Pat::parse_single(input)?; + + if input.peek(Token![:]) { + Ok(Pat::Type(PatType { + attrs, + pat: Box::new(pat), + colon_token: input.parse()?, + ty: input.parse()?, + })) + } else { + match &mut pat { + Pat::Const(pat) => pat.attrs = attrs, + Pat::Ident(pat) => pat.attrs = attrs, + Pat::Lit(pat) => pat.attrs = attrs, + Pat::Macro(pat) => pat.attrs = attrs, + Pat::Or(pat) => pat.attrs = attrs, + Pat::Paren(pat) => pat.attrs = attrs, + Pat::Path(pat) => pat.attrs = attrs, + Pat::Range(pat) => pat.attrs = attrs, + Pat::Reference(pat) => pat.attrs = attrs, + Pat::Rest(pat) => pat.attrs = attrs, + Pat::Slice(pat) => pat.attrs = attrs, + Pat::Struct(pat) => pat.attrs = attrs, + Pat::Tuple(pat) => pat.attrs = attrs, + Pat::TupleStruct(pat) => pat.attrs = attrs, + Pat::Type(_) => unreachable!(), + Pat::Verbatim(_) => {} + Pat::Wild(pat) => pat.attrs = attrs, + } + Ok(pat) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprWhile { + fn parse(input: ParseStream) -> Result<Self> { + let mut attrs = input.call(Attribute::parse_outer)?; + let label: Option<Label> = input.parse()?; + let while_token: Token![while] = input.parse()?; + let cond = Expr::parse_without_eager_brace(input)?; + + let content; + let brace_token = braced!(content in input); + attr::parsing::parse_inner(&content, &mut attrs)?; + let stmts = content.call(Block::parse_within)?; + + Ok(ExprWhile { + attrs, + label, + while_token, + cond: Box::new(cond), + body: Block { brace_token, stmts }, + }) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprConst { + fn parse(input: ParseStream) -> Result<Self> { + let const_token: Token![const] = input.parse()?; + + let content; + let brace_token = braced!(content in input); + let inner_attrs = content.call(Attribute::parse_inner)?; + let stmts = content.call(Block::parse_within)?; + + Ok(ExprConst { + attrs: inner_attrs, + const_token, + block: Block { brace_token, stmts }, + }) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for Label { + fn parse(input: ParseStream) -> Result<Self> { + Ok(Label { + name: input.parse()?, + colon_token: input.parse()?, + }) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for Option<Label> { + fn parse(input: ParseStream) -> Result<Self> { + if input.peek(Lifetime) { + input.parse().map(Some) + } else { + Ok(None) + } + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprContinue { + fn parse(input: ParseStream) -> Result<Self> { + Ok(ExprContinue { + attrs: Vec::new(), + continue_token: input.parse()?, + label: input.parse()?, + }) + } + } + + #[cfg(feature = "full")] + fn expr_break(input: ParseStream, allow_struct: AllowStruct) -> Result<ExprBreak> { + let break_token: Token![break] = input.parse()?; + + let ahead = input.fork(); + let label: Option<Lifetime> = ahead.parse()?; + if label.is_some() && ahead.peek(Token![:]) { + // Not allowed: `break 'label: loop {...}` + // Parentheses are required. `break ('label: loop {...})` + let _: Expr = input.parse()?; + let start_span = label.unwrap().apostrophe; + let end_span = input.cursor().prev_span(); + return Err(crate::error::new2( + start_span, + end_span, + "parentheses required", + )); + } + + input.advance_to(&ahead); + let expr = if Expr::peek(input) && (allow_struct.0 || !input.peek(token::Brace)) { + Some(input.parse()?) + } else { + None + }; + + Ok(ExprBreak { + attrs: Vec::new(), + break_token, + label, + expr, + }) + } + + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for FieldValue { + fn parse(input: ParseStream) -> Result<Self> { + let attrs = input.call(Attribute::parse_outer)?; + let member: Member = input.parse()?; + let (colon_token, value) = if input.peek(Token![:]) || !member.is_named() { + let colon_token: Token![:] = input.parse()?; + let value: Expr = input.parse()?; + (Some(colon_token), value) + } else if let Member::Named(ident) = &member { + let value = Expr::Path(ExprPath { + attrs: Vec::new(), + qself: None, + path: Path::from(ident.clone()), + }); + (None, value) + } else { + unreachable!() + }; + + Ok(FieldValue { + attrs, + member, + colon_token, + expr: value, + }) + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprStruct { + fn parse(input: ParseStream) -> Result<Self> { + let expr_style = true; + let (qself, path) = path::parsing::qpath(input, expr_style)?; + expr_struct_helper(input, qself, path) + } + } + + fn expr_struct_helper( + input: ParseStream, + qself: Option<QSelf>, + path: Path, + ) -> Result<ExprStruct> { + let content; + let brace_token = braced!(content in input); + + let mut fields = Punctuated::new(); + while !content.is_empty() { + if content.peek(Token![..]) { + return Ok(ExprStruct { + attrs: Vec::new(), + qself, + path, + brace_token, + fields, + dot2_token: Some(content.parse()?), + rest: if content.is_empty() { + None + } else { + Some(Box::new(content.parse()?)) + }, + }); + } + + fields.push(content.parse()?); + if content.is_empty() { + break; + } + let punct: Token![,] = content.parse()?; + fields.push_punct(punct); + } + + Ok(ExprStruct { + attrs: Vec::new(), + qself, + path, + brace_token, + fields, + dot2_token: None, + rest: None, + }) + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprUnsafe { + fn parse(input: ParseStream) -> Result<Self> { + let unsafe_token: Token![unsafe] = input.parse()?; + + let content; + let brace_token = braced!(content in input); + let inner_attrs = content.call(Attribute::parse_inner)?; + let stmts = content.call(Block::parse_within)?; + + Ok(ExprUnsafe { + attrs: inner_attrs, + unsafe_token, + block: Block { brace_token, stmts }, + }) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprBlock { + fn parse(input: ParseStream) -> Result<Self> { + let mut attrs = input.call(Attribute::parse_outer)?; + let label: Option<Label> = input.parse()?; + + let content; + let brace_token = braced!(content in input); + attr::parsing::parse_inner(&content, &mut attrs)?; + let stmts = content.call(Block::parse_within)?; + + Ok(ExprBlock { + attrs, + label, + block: Block { brace_token, stmts }, + }) + } + } + + #[cfg(feature = "full")] + fn expr_range(input: ParseStream, allow_struct: AllowStruct) -> Result<ExprRange> { + let limits: RangeLimits = input.parse()?; + let end = parse_range_end(input, &limits, allow_struct)?; + Ok(ExprRange { + attrs: Vec::new(), + start: None, + limits, + end, + }) + } + + #[cfg(feature = "full")] + fn parse_range_end( + input: ParseStream, + limits: &RangeLimits, + allow_struct: AllowStruct, + ) -> Result<Option<Box<Expr>>> { + if matches!(limits, RangeLimits::HalfOpen(_)) + && (input.is_empty() + || input.peek(Token![,]) + || input.peek(Token![;]) + || input.peek(Token![.]) && !input.peek(Token![..]) + || input.peek(Token![?]) + || input.peek(Token![=>]) + || !allow_struct.0 && input.peek(token::Brace) + || input.peek(Token![=]) + || input.peek(Token![+]) + || input.peek(Token![/]) + || input.peek(Token![%]) + || input.peek(Token![^]) + || input.peek(Token![>]) + || input.peek(Token![<=]) + || input.peek(Token![!=]) + || input.peek(Token![-=]) + || input.peek(Token![*=]) + || input.peek(Token![&=]) + || input.peek(Token![|=]) + || input.peek(Token![<<=]) + || input.peek(Token![as])) + { + Ok(None) + } else { + let end = parse_binop_rhs(input, allow_struct, Precedence::Range)?; + Ok(Some(end)) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for RangeLimits { + fn parse(input: ParseStream) -> Result<Self> { + let lookahead = input.lookahead1(); + let dot_dot = lookahead.peek(Token![..]); + let dot_dot_eq = dot_dot && lookahead.peek(Token![..=]); + let dot_dot_dot = dot_dot && input.peek(Token![...]); + if dot_dot_eq { + input.parse().map(RangeLimits::Closed) + } else if dot_dot && !dot_dot_dot { + input.parse().map(RangeLimits::HalfOpen) + } else { + Err(lookahead.error()) + } + } + } + + #[cfg(feature = "full")] + impl RangeLimits { + pub(crate) fn parse_obsolete(input: ParseStream) -> Result<Self> { + let lookahead = input.lookahead1(); + let dot_dot = lookahead.peek(Token![..]); + let dot_dot_eq = dot_dot && lookahead.peek(Token![..=]); + let dot_dot_dot = dot_dot && input.peek(Token![...]); + if dot_dot_eq { + input.parse().map(RangeLimits::Closed) + } else if dot_dot_dot { + let dot3: Token![...] = input.parse()?; + Ok(RangeLimits::Closed(Token)) + } else if dot_dot { + input.parse().map(RangeLimits::HalfOpen) + } else { + Err(lookahead.error()) + } + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for ExprPath { + fn parse(input: ParseStream) -> Result<Self> { + #[cfg(not(feature = "full"))] + let attrs = Vec::new(); + #[cfg(feature = "full")] + let attrs = input.call(Attribute::parse_outer)?; + + let expr_style = true; + let (qself, path) = path::parsing::qpath(input, expr_style)?; + + Ok(ExprPath { attrs, qself, path }) + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for Member { + fn parse(input: ParseStream) -> Result<Self> { + if input.peek(Ident) { + input.parse().map(Member::Named) + } else if input.peek(LitInt) { + input.parse().map(Member::Unnamed) + } else { + Err(input.error("expected identifier or integer")) + } + } + } + + #[cfg(feature = "full")] + impl Arm { + pub(crate) fn parse_multiple(input: ParseStream) -> Result<Vec<Self>> { + let mut arms = Vec::new(); + while !input.is_empty() { + arms.push(input.call(Arm::parse)?); + } + Ok(arms) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for Arm { + fn parse(input: ParseStream) -> Result<Arm> { + let requires_comma; + Ok(Arm { + attrs: input.call(Attribute::parse_outer)?, + pat: Pat::parse_multi_with_leading_vert(input)?, + guard: { + if input.peek(Token![if]) { + let if_token: Token![if] = input.parse()?; + let guard: Expr = input.parse()?; + Some((if_token, Box::new(guard))) + } else { + None + } + }, + fat_arrow_token: input.parse()?, + body: { + let body = Expr::parse_with_earlier_boundary_rule(input)?; + requires_comma = classify::requires_comma_to_be_match_arm(&body); + Box::new(body) + }, + comma: { + if requires_comma && !input.is_empty() { + Some(input.parse()?) + } else { + input.parse()? + } + }, + }) + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for Index { + fn parse(input: ParseStream) -> Result<Self> { + let lit: LitInt = input.parse()?; + if lit.suffix().is_empty() { + Ok(Index { + index: lit + .base10_digits() + .parse() + .map_err(|err| Error::new(lit.span(), err))?, + span: lit.span(), + }) + } else { + Err(Error::new(lit.span(), "expected unsuffixed integer")) + } + } + } + + fn multi_index(e: &mut Expr, dot_token: &mut Token![.], float: LitFloat) -> Result<bool> { + let float_token = float.token(); + let float_span = float_token.span(); + let mut float_repr = float_token.to_string(); + let trailing_dot = float_repr.ends_with('.'); + if trailing_dot { + float_repr.truncate(float_repr.len() - 1); + } + + let mut offset = 0; + for part in float_repr.split('.') { + let mut index: Index = + crate::parse_str(part).map_err(|err| Error::new(float_span, err))?; + let part_end = offset + part.len(); + index.span = float_token.subspan(offset..part_end).unwrap_or(float_span); + + let base = mem::replace(e, Expr::PLACEHOLDER); + *e = Expr::Field(ExprField { + attrs: Vec::new(), + base: Box::new(base), + dot_token: Token, + member: Member::Unnamed(index), + }); + + let dot_span = float_token + .subspan(part_end..part_end + 1) + .unwrap_or(float_span); + *dot_token = Token; + offset = part_end + 1; + } + + Ok(!trailing_dot) + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))] + impl Parse for PointerMutability { + fn parse(input: ParseStream) -> Result<Self> { + let lookahead = input.lookahead1(); + if lookahead.peek(Token![const]) { + Ok(PointerMutability::Const(input.parse()?)) + } else if lookahead.peek(Token![mut]) { + Ok(PointerMutability::Mut(input.parse()?)) + } else { + Err(lookahead.error()) + } + } + } + + fn check_cast(input: ParseStream) -> Result<()> { + let kind = if input.peek(Token![.]) && !input.peek(Token![..]) { + if input.peek2(Token![await]) { + "`.await`" + } else if input.peek2(Ident) && (input.peek3(token::Paren) || input.peek3(Token![::])) { + "a method call" + } else { + "a field access" + } + } else if input.peek(Token![?]) { + "`?`" + } else if input.peek(token::Bracket) { + "indexing" + } else if input.peek(token::Paren) { + "a function call" + } else { + return Ok(()); + }; + let msg = format!("casts cannot be followed by {}", kind); + Err(input.error(msg)) + } +} + +#[cfg(feature = "printing")] +pub(crate) mod printing { + use crate::attr::Attribute; + #[cfg(feature = "full")] + use crate::attr::FilterAttrs; + #[cfg(feature = "full")] + use crate::classify; + #[cfg(feature = "full")] + use crate::expr::{ + Arm, ExprArray, ExprAssign, ExprAsync, ExprAwait, ExprBlock, ExprBreak, ExprClosure, + ExprConst, ExprContinue, ExprForLoop, ExprIf, ExprInfer, ExprLet, ExprLoop, ExprMatch, + ExprRange, ExprRawAddr, ExprRepeat, ExprReturn, ExprTry, ExprTryBlock, ExprUnsafe, + ExprWhile, ExprYield, Label, PointerMutability, RangeLimits, + }; + use crate::expr::{ + Expr, ExprBinary, ExprCall, ExprCast, ExprField, ExprGroup, ExprIndex, ExprLit, ExprMacro, + ExprMethodCall, ExprParen, ExprPath, ExprReference, ExprStruct, ExprTuple, ExprUnary, + FieldValue, Index, Member, + }; + use crate::fixup::FixupContext; + use crate::op::BinOp; + use crate::path; + use crate::path::printing::PathStyle; + use crate::precedence::Precedence; + use crate::token; + #[cfg(feature = "full")] + use crate::ty::ReturnType; + use proc_macro2::{Literal, Span, TokenStream}; + use quote::{ToTokens, TokenStreamExt}; + + #[cfg(feature = "full")] + pub(crate) fn outer_attrs_to_tokens(attrs: &[Attribute], tokens: &mut TokenStream) { + tokens.append_all(attrs.outer()); + } + + #[cfg(feature = "full")] + fn inner_attrs_to_tokens(attrs: &[Attribute], tokens: &mut TokenStream) { + tokens.append_all(attrs.inner()); + } + + #[cfg(not(feature = "full"))] + pub(crate) fn outer_attrs_to_tokens(_attrs: &[Attribute], _tokens: &mut TokenStream) {} + + pub(crate) fn print_subexpression( + expr: &Expr, + needs_group: bool, + tokens: &mut TokenStream, + mut fixup: FixupContext, + ) { + if needs_group { + // If we are surrounding the whole cond in parentheses, such as: + // + // if (return Struct {}) {} + // + // then there is no need for parenthesizing the individual struct + // expressions within. On the other hand if the whole cond is not + // parenthesized, then print_expr must parenthesize exterior struct + // literals. + // + // if x == (Struct {}) {} + // + fixup = FixupContext::NONE; + } + + let do_print_expr = |tokens: &mut TokenStream| print_expr(expr, tokens, fixup); + + if needs_group { + token::Paren::default().surround(tokens, do_print_expr); + } else { + do_print_expr(tokens); + } + } + + pub(crate) fn print_expr(expr: &Expr, tokens: &mut TokenStream, mut fixup: FixupContext) { + #[cfg(feature = "full")] + let needs_group = fixup.parenthesize(expr); + #[cfg(not(feature = "full"))] + let needs_group = false; + + if needs_group { + fixup = FixupContext::NONE; + } + + let do_print_expr = |tokens: &mut TokenStream| match expr { + #[cfg(feature = "full")] + Expr::Array(e) => e.to_tokens(tokens), + #[cfg(feature = "full")] + Expr::Assign(e) => print_expr_assign(e, tokens, fixup), + #[cfg(feature = "full")] + Expr::Async(e) => e.to_tokens(tokens), + #[cfg(feature = "full")] + Expr::Await(e) => print_expr_await(e, tokens, fixup), + Expr::Binary(e) => print_expr_binary(e, tokens, fixup), + #[cfg(feature = "full")] + Expr::Block(e) => e.to_tokens(tokens), + #[cfg(feature = "full")] + Expr::Break(e) => print_expr_break(e, tokens, fixup), + Expr::Call(e) => print_expr_call(e, tokens, fixup), + Expr::Cast(e) => print_expr_cast(e, tokens, fixup), + #[cfg(feature = "full")] + Expr::Closure(e) => print_expr_closure(e, tokens, fixup), + #[cfg(feature = "full")] + Expr::Const(e) => e.to_tokens(tokens), + #[cfg(feature = "full")] + Expr::Continue(e) => e.to_tokens(tokens), + Expr::Field(e) => print_expr_field(e, tokens, fixup), + #[cfg(feature = "full")] + Expr::ForLoop(e) => e.to_tokens(tokens), + Expr::Group(e) => e.to_tokens(tokens), + #[cfg(feature = "full")] + Expr::If(e) => e.to_tokens(tokens), + Expr::Index(e) => print_expr_index(e, tokens, fixup), + #[cfg(feature = "full")] + Expr::Infer(e) => e.to_tokens(tokens), + #[cfg(feature = "full")] + Expr::Let(e) => print_expr_let(e, tokens, fixup), + Expr::Lit(e) => e.to_tokens(tokens), + #[cfg(feature = "full")] + Expr::Loop(e) => e.to_tokens(tokens), + Expr::Macro(e) => e.to_tokens(tokens), + #[cfg(feature = "full")] + Expr::Match(e) => e.to_tokens(tokens), + Expr::MethodCall(e) => print_expr_method_call(e, tokens, fixup), + Expr::Paren(e) => e.to_tokens(tokens), + Expr::Path(e) => e.to_tokens(tokens), + #[cfg(feature = "full")] + Expr::Range(e) => print_expr_range(e, tokens, fixup), + #[cfg(feature = "full")] + Expr::RawAddr(e) => print_expr_raw_addr(e, tokens, fixup), + Expr::Reference(e) => print_expr_reference(e, tokens, fixup), + #[cfg(feature = "full")] + Expr::Repeat(e) => e.to_tokens(tokens), + #[cfg(feature = "full")] + Expr::Return(e) => print_expr_return(e, tokens, fixup), + Expr::Struct(e) => e.to_tokens(tokens), + #[cfg(feature = "full")] + Expr::Try(e) => print_expr_try(e, tokens, fixup), + #[cfg(feature = "full")] + Expr::TryBlock(e) => e.to_tokens(tokens), + Expr::Tuple(e) => e.to_tokens(tokens), + Expr::Unary(e) => print_expr_unary(e, tokens, fixup), + #[cfg(feature = "full")] + Expr::Unsafe(e) => e.to_tokens(tokens), + Expr::Verbatim(e) => e.to_tokens(tokens), + #[cfg(feature = "full")] + Expr::While(e) => e.to_tokens(tokens), + #[cfg(feature = "full")] + Expr::Yield(e) => print_expr_yield(e, tokens, fixup), + + #[cfg(not(feature = "full"))] + _ => unreachable!(), + }; + + if needs_group { + token::Paren::default().surround(tokens, do_print_expr); + } else { + do_print_expr(tokens); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprArray { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.bracket_token.surround(tokens, |tokens| { + self.elems.to_tokens(tokens); + }); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprAssign { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_assign(self, tokens, FixupContext::NONE); + } + } + + #[cfg(feature = "full")] + fn print_expr_assign(e: &ExprAssign, tokens: &mut TokenStream, mut fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + + let needs_group = !e.attrs.is_empty(); + if needs_group { + fixup = FixupContext::NONE; + } + + let do_print_expr = |tokens: &mut TokenStream| { + let (left_prec, left_fixup) = fixup.leftmost_subexpression_with_operator( + &e.left, + false, + false, + Precedence::Assign, + ); + print_subexpression(&e.left, left_prec <= Precedence::Range, tokens, left_fixup); + e.eq_token.to_tokens(tokens); + print_expr( + &e.right, + tokens, + fixup.rightmost_subexpression_fixup(false, false, Precedence::Assign), + ); + }; + + if needs_group { + token::Paren::default().surround(tokens, do_print_expr); + } else { + do_print_expr(tokens); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprAsync { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.async_token.to_tokens(tokens); + self.capture.to_tokens(tokens); + self.block.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprAwait { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_await(self, tokens, FixupContext::NONE); + } + } + + #[cfg(feature = "full")] + fn print_expr_await(e: &ExprAwait, tokens: &mut TokenStream, fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + let (left_prec, left_fixup) = fixup.leftmost_subexpression_with_dot(&e.base); + print_subexpression( + &e.base, + left_prec < Precedence::Unambiguous, + tokens, + left_fixup, + ); + e.dot_token.to_tokens(tokens); + e.await_token.to_tokens(tokens); + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprBinary { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_binary(self, tokens, FixupContext::NONE); + } + } + + fn print_expr_binary(e: &ExprBinary, tokens: &mut TokenStream, mut fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + + let needs_group = !e.attrs.is_empty(); + if needs_group { + fixup = FixupContext::NONE; + } + + let do_print_expr = |tokens: &mut TokenStream| { + let binop_prec = Precedence::of_binop(&e.op); + let (left_prec, left_fixup) = fixup.leftmost_subexpression_with_operator( + &e.left, + #[cfg(feature = "full")] + match &e.op { + BinOp::Sub(_) + | BinOp::Mul(_) + | BinOp::And(_) + | BinOp::Or(_) + | BinOp::BitAnd(_) + | BinOp::BitOr(_) + | BinOp::Shl(_) + | BinOp::Lt(_) => true, + _ => false, + }, + match &e.op { + BinOp::Shl(_) | BinOp::Lt(_) => true, + _ => false, + }, + #[cfg(feature = "full")] + binop_prec, + ); + let left_needs_group = match binop_prec { + Precedence::Assign => left_prec <= Precedence::Range, + Precedence::Compare => left_prec <= binop_prec, + _ => left_prec < binop_prec, + }; + + let right_fixup = fixup.rightmost_subexpression_fixup( + #[cfg(feature = "full")] + false, + #[cfg(feature = "full")] + false, + #[cfg(feature = "full")] + binop_prec, + ); + let right_needs_group = binop_prec != Precedence::Assign + && right_fixup.rightmost_subexpression_precedence(&e.right) <= binop_prec; + + print_subexpression(&e.left, left_needs_group, tokens, left_fixup); + e.op.to_tokens(tokens); + print_subexpression(&e.right, right_needs_group, tokens, right_fixup); + }; + + if needs_group { + token::Paren::default().surround(tokens, do_print_expr); + } else { + do_print_expr(tokens); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprBlock { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.label.to_tokens(tokens); + self.block.brace_token.surround(tokens, |tokens| { + inner_attrs_to_tokens(&self.attrs, tokens); + tokens.append_all(&self.block.stmts); + }); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprBreak { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_break(self, tokens, FixupContext::NONE); + } + } + + #[cfg(feature = "full")] + fn print_expr_break(e: &ExprBreak, tokens: &mut TokenStream, fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + e.break_token.to_tokens(tokens); + e.label.to_tokens(tokens); + if let Some(value) = &e.expr { + print_subexpression( + value, + // Parenthesize `break 'inner: loop { break 'inner 1 } + 1` + // ^---------------------------------^ + e.label.is_none() && classify::expr_leading_label(value), + tokens, + fixup.rightmost_subexpression_fixup(true, true, Precedence::Jump), + ); + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprCall { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_call(self, tokens, FixupContext::NONE); + } + } + + fn print_expr_call(e: &ExprCall, tokens: &mut TokenStream, fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + + let (left_prec, left_fixup) = fixup.leftmost_subexpression_with_operator( + &e.func, + #[cfg(feature = "full")] + true, + false, + #[cfg(feature = "full")] + Precedence::Unambiguous, + ); + let needs_group = if let Expr::Field(func) = &*e.func { + func.member.is_named() + } else { + left_prec < Precedence::Unambiguous + }; + print_subexpression(&e.func, needs_group, tokens, left_fixup); + + e.paren_token.surround(tokens, |tokens| { + e.args.to_tokens(tokens); + }); + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprCast { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_cast(self, tokens, FixupContext::NONE); + } + } + + fn print_expr_cast(e: &ExprCast, tokens: &mut TokenStream, mut fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + + let needs_group = !e.attrs.is_empty(); + if needs_group { + fixup = FixupContext::NONE; + } + + let do_print_expr = |tokens: &mut TokenStream| { + let (left_prec, left_fixup) = fixup.leftmost_subexpression_with_operator( + &e.expr, + #[cfg(feature = "full")] + false, + false, + #[cfg(feature = "full")] + Precedence::Cast, + ); + print_subexpression(&e.expr, left_prec < Precedence::Cast, tokens, left_fixup); + e.as_token.to_tokens(tokens); + e.ty.to_tokens(tokens); + }; + + if needs_group { + token::Paren::default().surround(tokens, do_print_expr); + } else { + do_print_expr(tokens); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprClosure { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_closure(self, tokens, FixupContext::NONE); + } + } + + #[cfg(feature = "full")] + fn print_expr_closure(e: &ExprClosure, tokens: &mut TokenStream, fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + e.lifetimes.to_tokens(tokens); + e.constness.to_tokens(tokens); + e.movability.to_tokens(tokens); + e.asyncness.to_tokens(tokens); + e.capture.to_tokens(tokens); + e.or1_token.to_tokens(tokens); + e.inputs.to_tokens(tokens); + e.or2_token.to_tokens(tokens); + e.output.to_tokens(tokens); + if matches!(e.output, ReturnType::Default) + || matches!(&*e.body, Expr::Block(body) if body.attrs.is_empty() && body.label.is_none()) + { + print_expr( + &e.body, + tokens, + fixup.rightmost_subexpression_fixup(false, false, Precedence::Jump), + ); + } else { + token::Brace::default().surround(tokens, |tokens| { + print_expr(&e.body, tokens, FixupContext::new_stmt()); + }); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprConst { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.const_token.to_tokens(tokens); + self.block.brace_token.surround(tokens, |tokens| { + inner_attrs_to_tokens(&self.attrs, tokens); + tokens.append_all(&self.block.stmts); + }); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprContinue { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.continue_token.to_tokens(tokens); + self.label.to_tokens(tokens); + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprField { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_field(self, tokens, FixupContext::NONE); + } + } + + fn print_expr_field(e: &ExprField, tokens: &mut TokenStream, fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + let (left_prec, left_fixup) = fixup.leftmost_subexpression_with_dot(&e.base); + print_subexpression( + &e.base, + left_prec < Precedence::Unambiguous, + tokens, + left_fixup, + ); + e.dot_token.to_tokens(tokens); + e.member.to_tokens(tokens); + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprForLoop { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.label.to_tokens(tokens); + self.for_token.to_tokens(tokens); + self.pat.to_tokens(tokens); + self.in_token.to_tokens(tokens); + print_expr(&self.expr, tokens, FixupContext::new_condition()); + self.body.brace_token.surround(tokens, |tokens| { + inner_attrs_to_tokens(&self.attrs, tokens); + tokens.append_all(&self.body.stmts); + }); + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprGroup { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.group_token.surround(tokens, |tokens| { + self.expr.to_tokens(tokens); + }); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprIf { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + + let mut expr = self; + loop { + expr.if_token.to_tokens(tokens); + print_expr(&expr.cond, tokens, FixupContext::new_condition()); + expr.then_branch.to_tokens(tokens); + + let (else_token, else_) = match &expr.else_branch { + Some(else_branch) => else_branch, + None => break, + }; + + else_token.to_tokens(tokens); + match &**else_ { + Expr::If(next) => { + expr = next; + } + Expr::Block(last) => { + last.to_tokens(tokens); + break; + } + // If this is not one of the valid expressions to exist in + // an else clause, wrap it in a block. + other => { + token::Brace::default().surround(tokens, |tokens| { + print_expr(other, tokens, FixupContext::new_stmt()); + }); + break; + } + } + } + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprIndex { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_index(self, tokens, FixupContext::NONE); + } + } + + fn print_expr_index(e: &ExprIndex, tokens: &mut TokenStream, fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + let (left_prec, left_fixup) = fixup.leftmost_subexpression_with_operator( + &e.expr, + #[cfg(feature = "full")] + true, + false, + #[cfg(feature = "full")] + Precedence::Unambiguous, + ); + print_subexpression( + &e.expr, + left_prec < Precedence::Unambiguous, + tokens, + left_fixup, + ); + e.bracket_token.surround(tokens, |tokens| { + e.index.to_tokens(tokens); + }); + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprInfer { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.underscore_token.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprLet { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_let(self, tokens, FixupContext::NONE); + } + } + + #[cfg(feature = "full")] + fn print_expr_let(e: &ExprLet, tokens: &mut TokenStream, fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + e.let_token.to_tokens(tokens); + e.pat.to_tokens(tokens); + e.eq_token.to_tokens(tokens); + let (right_prec, right_fixup) = fixup.rightmost_subexpression(&e.expr, Precedence::Let); + print_subexpression(&e.expr, right_prec < Precedence::Let, tokens, right_fixup); + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprLit { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.lit.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprLoop { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.label.to_tokens(tokens); + self.loop_token.to_tokens(tokens); + self.body.brace_token.surround(tokens, |tokens| { + inner_attrs_to_tokens(&self.attrs, tokens); + tokens.append_all(&self.body.stmts); + }); + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprMacro { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.mac.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprMatch { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.match_token.to_tokens(tokens); + print_expr(&self.expr, tokens, FixupContext::new_condition()); + self.brace_token.surround(tokens, |tokens| { + inner_attrs_to_tokens(&self.attrs, tokens); + for (i, arm) in self.arms.iter().enumerate() { + arm.to_tokens(tokens); + // Ensure that we have a comma after a non-block arm, except + // for the last one. + let is_last = i == self.arms.len() - 1; + if !is_last + && classify::requires_comma_to_be_match_arm(&arm.body) + && arm.comma.is_none() + { + <Token![,]>::default().to_tokens(tokens); + } + } + }); + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprMethodCall { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_method_call(self, tokens, FixupContext::NONE); + } + } + + fn print_expr_method_call(e: &ExprMethodCall, tokens: &mut TokenStream, fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + let (left_prec, left_fixup) = fixup.leftmost_subexpression_with_dot(&e.receiver); + print_subexpression( + &e.receiver, + left_prec < Precedence::Unambiguous, + tokens, + left_fixup, + ); + e.dot_token.to_tokens(tokens); + e.method.to_tokens(tokens); + if let Some(turbofish) = &e.turbofish { + path::printing::print_angle_bracketed_generic_arguments( + tokens, + turbofish, + PathStyle::Expr, + ); + } + e.paren_token.surround(tokens, |tokens| { + e.args.to_tokens(tokens); + }); + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprParen { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.paren_token.surround(tokens, |tokens| { + self.expr.to_tokens(tokens); + }); + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprPath { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + path::printing::print_qpath(tokens, &self.qself, &self.path, PathStyle::Expr); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprRange { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_range(self, tokens, FixupContext::NONE); + } + } + + #[cfg(feature = "full")] + fn print_expr_range(e: &ExprRange, tokens: &mut TokenStream, mut fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + + let needs_group = !e.attrs.is_empty(); + if needs_group { + fixup = FixupContext::NONE; + } + + let do_print_expr = |tokens: &mut TokenStream| { + if let Some(start) = &e.start { + let (left_prec, left_fixup) = fixup.leftmost_subexpression_with_operator( + start, + true, + false, + Precedence::Range, + ); + print_subexpression(start, left_prec <= Precedence::Range, tokens, left_fixup); + } + e.limits.to_tokens(tokens); + if let Some(end) = &e.end { + let right_fixup = + fixup.rightmost_subexpression_fixup(false, true, Precedence::Range); + let right_prec = right_fixup.rightmost_subexpression_precedence(end); + print_subexpression(end, right_prec <= Precedence::Range, tokens, right_fixup); + } + }; + + if needs_group { + token::Paren::default().surround(tokens, do_print_expr); + } else { + do_print_expr(tokens); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprRawAddr { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_raw_addr(self, tokens, FixupContext::NONE); + } + } + + #[cfg(feature = "full")] + fn print_expr_raw_addr(e: &ExprRawAddr, tokens: &mut TokenStream, fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + e.and_token.to_tokens(tokens); + e.raw.to_tokens(tokens); + e.mutability.to_tokens(tokens); + let (right_prec, right_fixup) = fixup.rightmost_subexpression(&e.expr, Precedence::Prefix); + print_subexpression( + &e.expr, + right_prec < Precedence::Prefix, + tokens, + right_fixup, + ); + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprReference { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_reference(self, tokens, FixupContext::NONE); + } + } + + fn print_expr_reference(e: &ExprReference, tokens: &mut TokenStream, fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + e.and_token.to_tokens(tokens); + e.mutability.to_tokens(tokens); + let (right_prec, right_fixup) = fixup.rightmost_subexpression( + &e.expr, + #[cfg(feature = "full")] + Precedence::Prefix, + ); + print_subexpression( + &e.expr, + right_prec < Precedence::Prefix, + tokens, + right_fixup, + ); + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprRepeat { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.bracket_token.surround(tokens, |tokens| { + self.expr.to_tokens(tokens); + self.semi_token.to_tokens(tokens); + self.len.to_tokens(tokens); + }); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprReturn { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_return(self, tokens, FixupContext::NONE); + } + } + + #[cfg(feature = "full")] + fn print_expr_return(e: &ExprReturn, tokens: &mut TokenStream, fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + e.return_token.to_tokens(tokens); + if let Some(expr) = &e.expr { + print_expr( + expr, + tokens, + fixup.rightmost_subexpression_fixup(true, false, Precedence::Jump), + ); + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprStruct { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + path::printing::print_qpath(tokens, &self.qself, &self.path, PathStyle::Expr); + self.brace_token.surround(tokens, |tokens| { + self.fields.to_tokens(tokens); + if let Some(dot2_token) = &self.dot2_token { + dot2_token.to_tokens(tokens); + } else if self.rest.is_some() { + Token).to_tokens(tokens); + } + self.rest.to_tokens(tokens); + }); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprTry { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_try(self, tokens, FixupContext::NONE); + } + } + + #[cfg(feature = "full")] + fn print_expr_try(e: &ExprTry, tokens: &mut TokenStream, fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + let (left_prec, left_fixup) = fixup.leftmost_subexpression_with_dot(&e.expr); + print_subexpression( + &e.expr, + left_prec < Precedence::Unambiguous, + tokens, + left_fixup, + ); + e.question_token.to_tokens(tokens); + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprTryBlock { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.try_token.to_tokens(tokens); + self.block.to_tokens(tokens); + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprTuple { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.paren_token.surround(tokens, |tokens| { + self.elems.to_tokens(tokens); + // If we only have one argument, we need a trailing comma to + // distinguish ExprTuple from ExprParen. + if self.elems.len() == 1 && !self.elems.trailing_punct() { + <Token![,]>::default().to_tokens(tokens); + } + }); + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprUnary { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_unary(self, tokens, FixupContext::NONE); + } + } + + fn print_expr_unary(e: &ExprUnary, tokens: &mut TokenStream, fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + e.op.to_tokens(tokens); + let (right_prec, right_fixup) = fixup.rightmost_subexpression( + &e.expr, + #[cfg(feature = "full")] + Precedence::Prefix, + ); + print_subexpression( + &e.expr, + right_prec < Precedence::Prefix, + tokens, + right_fixup, + ); + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprUnsafe { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.unsafe_token.to_tokens(tokens); + self.block.brace_token.surround(tokens, |tokens| { + inner_attrs_to_tokens(&self.attrs, tokens); + tokens.append_all(&self.block.stmts); + }); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprWhile { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.label.to_tokens(tokens); + self.while_token.to_tokens(tokens); + print_expr(&self.cond, tokens, FixupContext::new_condition()); + self.body.brace_token.surround(tokens, |tokens| { + inner_attrs_to_tokens(&self.attrs, tokens); + tokens.append_all(&self.body.stmts); + }); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for ExprYield { + fn to_tokens(&self, tokens: &mut TokenStream) { + print_expr_yield(self, tokens, FixupContext::NONE); + } + } + + #[cfg(feature = "full")] + fn print_expr_yield(e: &ExprYield, tokens: &mut TokenStream, fixup: FixupContext) { + outer_attrs_to_tokens(&e.attrs, tokens); + e.yield_token.to_tokens(tokens); + if let Some(expr) = &e.expr { + print_expr( + expr, + tokens, + fixup.rightmost_subexpression_fixup(true, false, Precedence::Jump), + ); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for Arm { + fn to_tokens(&self, tokens: &mut TokenStream) { + tokens.append_all(&self.attrs); + self.pat.to_tokens(tokens); + if let Some((if_token, guard)) = &self.guard { + if_token.to_tokens(tokens); + guard.to_tokens(tokens); + } + self.fat_arrow_token.to_tokens(tokens); + print_expr(&self.body, tokens, FixupContext::new_match_arm()); + self.comma.to_tokens(tokens); + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for FieldValue { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.member.to_tokens(tokens); + if let Some(colon_token) = &self.colon_token { + colon_token.to_tokens(tokens); + self.expr.to_tokens(tokens); + } + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for Index { + fn to_tokens(&self, tokens: &mut TokenStream) { + let mut lit = Literal::i64_unsuffixed(i64::from(self.index)); + lit.set_span(self.span); + tokens.append(lit); + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for Label { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.name.to_tokens(tokens); + self.colon_token.to_tokens(tokens); + } + } + + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for Member { + fn to_tokens(&self, tokens: &mut TokenStream) { + match self { + Member::Named(ident) => ident.to_tokens(tokens), + Member::Unnamed(index) => index.to_tokens(tokens), + } + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for RangeLimits { + fn to_tokens(&self, tokens: &mut TokenStream) { + match self { + RangeLimits::HalfOpen(t) => t.to_tokens(tokens), + RangeLimits::Closed(t) => t.to_tokens(tokens), + } + } + } + + #[cfg(feature = "full")] + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ToTokens for PointerMutability { + fn to_tokens(&self, tokens: &mut TokenStream) { + match self { + PointerMutability::Const(const_token) => const_token.to_tokens(tokens), + PointerMutability::Mut(mut_token) => mut_token.to_tokens(tokens), + } + } + } +} |