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Diffstat (limited to 'syn/src/expr.rs')
| -rw-r--r-- | syn/src/expr.rs | 3236 |
1 files changed, 3236 insertions, 0 deletions
diff --git a/syn/src/expr.rs b/syn/src/expr.rs new file mode 100644 index 0000000..603dc32 --- /dev/null +++ b/syn/src/expr.rs @@ -0,0 +1,3236 @@ +use super::*; +use crate::punctuated::Punctuated; +#[cfg(feature = "extra-traits")] +use crate::tt::TokenStreamHelper; +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 if Syn is built with the `"derive"` or `"full"` + /// feature.* + /// + /// # 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`. + pub enum Expr #manual_extra_traits { + /// A slice literal expression: `[a, b, c, d]`. + Array(ExprArray), + + /// An assignment expression: `a = compute()`. + Assign(ExprAssign), + + /// A compound assignment expression: `counter += 1`. + AssignOp(ExprAssignOp), + + /// 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 box expression: `box f`. + Box(ExprBox), + + /// 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 `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), + + /// 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), + + /// 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 type ascription expression: `foo: f64`. + Type(ExprType), + + /// 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), + + #[doc(hidden)] + __Nonexhaustive, + } +} + +ast_struct! { + /// A slice literal expression: `[a, b, c, d]`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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()`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprAssign #full { + pub attrs: Vec<Attribute>, + pub left: Box<Expr>, + pub eq_token: Token![=], + pub right: Box<Expr>, + } +} + +ast_struct! { + /// A compound assignment expression: `counter += 1`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprAssignOp #full { + pub attrs: Vec<Attribute>, + pub left: Box<Expr>, + pub op: BinOp, + pub right: Box<Expr>, + } +} + +ast_struct! { + /// An async block: `async { ... }`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct ExprBinary { + pub attrs: Vec<Attribute>, + pub left: Box<Expr>, + pub op: BinOp, + pub right: Box<Expr>, + } +} + +ast_struct! { + /// A blocked scope: `{ ... }`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprBlock #full { + pub attrs: Vec<Attribute>, + pub label: Option<Label>, + pub block: Block, + } +} + +ast_struct! { + /// A box expression: `box f`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprBox #full { + pub attrs: Vec<Attribute>, + pub box_token: Token![box], + pub expr: Box<Expr>, + } +} + +ast_struct! { + /// A `break`, with an optional label to break and an optional + /// expression. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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)`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + 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`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + 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`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprClosure #full { + pub attrs: Vec<Attribute>, + pub asyncness: Option<Token![async]>, + pub movability: Option<Token![static]>, + 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 `continue`, with an optional label. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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`). + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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 { ... }`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprForLoop #full { + pub attrs: Vec<Attribute>, + pub label: Option<Label>, + pub for_token: Token![for], + pub pat: 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`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprGroup #full { + 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. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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]`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct ExprIndex { + pub attrs: Vec<Attribute>, + pub expr: Box<Expr>, + pub bracket_token: token::Bracket, + pub index: Box<Expr>, + } +} + +ast_struct! { + /// A `let` guard: `let Some(x) = opt`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprLet #full { + pub attrs: Vec<Attribute>, + pub let_token: Token![let], + pub pat: Pat, + pub eq_token: Token![=], + pub expr: Box<Expr>, + } +} + +ast_struct! { + /// A literal in place of an expression: `1`, `"foo"`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct ExprLit { + pub attrs: Vec<Attribute>, + pub lit: Lit, + } +} + +ast_struct! { + /// Conditionless loop: `loop { ... }`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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)`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprMacro #full { + pub attrs: Vec<Attribute>, + pub mac: Macro, + } +} + +ast_struct! { + /// A `match` expression: `match n { Some(n) => {}, None => {} }`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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)`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprMethodCall #full { + pub attrs: Vec<Attribute>, + pub receiver: Box<Expr>, + pub dot_token: Token![.], + pub method: Ident, + pub turbofish: Option<MethodTurbofish>, + pub paren_token: token::Paren, + pub args: Punctuated<Expr, Token![,]>, + } +} + +ast_struct! { + /// A parenthesized expression: `(a + b)`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + 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`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprRange #full { + pub attrs: Vec<Attribute>, + pub from: Option<Box<Expr>>, + pub limits: RangeLimits, + pub to: Option<Box<Expr>>, + } +} + +ast_struct! { + /// A referencing operation: `&a` or `&mut a`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprReference #full { + pub attrs: Vec<Attribute>, + pub and_token: Token![&], + pub raw: Reserved, + pub mutability: Option<Token![mut]>, + pub expr: Box<Expr>, + } +} + +ast_struct! { + /// An array literal constructed from one repeated element: `[0u8; N]`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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 }`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprStruct #full { + pub attrs: Vec<Attribute>, + 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?`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprTry #full { + pub attrs: Vec<Attribute>, + pub expr: Box<Expr>, + pub question_token: Token![?], + } +} + +ast_struct! { + /// A try block: `try { ... }`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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)`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprTuple #full { + pub attrs: Vec<Attribute>, + pub paren_token: token::Paren, + pub elems: Punctuated<Expr, Token![,]>, + } +} + +ast_struct! { + /// A type ascription expression: `foo: f64`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprType #full { + pub attrs: Vec<Attribute>, + pub expr: Box<Expr>, + pub colon_token: Token![:], + pub ty: Box<Type>, + } +} + +ast_struct! { + /// A unary operation: `!x`, `*x`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct ExprUnary { + pub attrs: Vec<Attribute>, + pub op: UnOp, + pub expr: Box<Expr>, + } +} + +ast_struct! { + /// An unsafe block: `unsafe { ... }`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprUnsafe #full { + pub attrs: Vec<Attribute>, + pub unsafe_token: Token![unsafe], + pub block: Block, + } +} + +ast_struct! { + /// A while loop: `while expr { ... }`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprYield #full { + pub attrs: Vec<Attribute>, + pub yield_token: Token![yield], + pub expr: Option<Box<Expr>>, + } +} + +#[cfg(feature = "extra-traits")] +impl Eq for Expr {} + +#[cfg(feature = "extra-traits")] +impl PartialEq for Expr { + fn eq(&self, other: &Self) -> bool { + match (self, other) { + (Expr::Array(this), Expr::Array(other)) => this == other, + (Expr::Assign(this), Expr::Assign(other)) => this == other, + (Expr::AssignOp(this), Expr::AssignOp(other)) => this == other, + (Expr::Async(this), Expr::Async(other)) => this == other, + (Expr::Await(this), Expr::Await(other)) => this == other, + (Expr::Binary(this), Expr::Binary(other)) => this == other, + (Expr::Block(this), Expr::Block(other)) => this == other, + (Expr::Box(this), Expr::Box(other)) => this == other, + (Expr::Break(this), Expr::Break(other)) => this == other, + (Expr::Call(this), Expr::Call(other)) => this == other, + (Expr::Cast(this), Expr::Cast(other)) => this == other, + (Expr::Closure(this), Expr::Closure(other)) => this == other, + (Expr::Continue(this), Expr::Continue(other)) => this == other, + (Expr::Field(this), Expr::Field(other)) => this == other, + (Expr::ForLoop(this), Expr::ForLoop(other)) => this == other, + (Expr::Group(this), Expr::Group(other)) => this == other, + (Expr::If(this), Expr::If(other)) => this == other, + (Expr::Index(this), Expr::Index(other)) => this == other, + (Expr::Let(this), Expr::Let(other)) => this == other, + (Expr::Lit(this), Expr::Lit(other)) => this == other, + (Expr::Loop(this), Expr::Loop(other)) => this == other, + (Expr::Macro(this), Expr::Macro(other)) => this == other, + (Expr::Match(this), Expr::Match(other)) => this == other, + (Expr::MethodCall(this), Expr::MethodCall(other)) => this == other, + (Expr::Paren(this), Expr::Paren(other)) => this == other, + (Expr::Path(this), Expr::Path(other)) => this == other, + (Expr::Range(this), Expr::Range(other)) => this == other, + (Expr::Reference(this), Expr::Reference(other)) => this == other, + (Expr::Repeat(this), Expr::Repeat(other)) => this == other, + (Expr::Return(this), Expr::Return(other)) => this == other, + (Expr::Struct(this), Expr::Struct(other)) => this == other, + (Expr::Try(this), Expr::Try(other)) => this == other, + (Expr::TryBlock(this), Expr::TryBlock(other)) => this == other, + (Expr::Tuple(this), Expr::Tuple(other)) => this == other, + (Expr::Type(this), Expr::Type(other)) => this == other, + (Expr::Unary(this), Expr::Unary(other)) => this == other, + (Expr::Unsafe(this), Expr::Unsafe(other)) => this == other, + (Expr::Verbatim(this), Expr::Verbatim(other)) => { + TokenStreamHelper(this) == TokenStreamHelper(other) + } + (Expr::While(this), Expr::While(other)) => this == other, + (Expr::Yield(this), Expr::Yield(other)) => this == other, + _ => false, + } + } +} + +#[cfg(feature = "extra-traits")] +impl Hash for Expr { + fn hash<H>(&self, hash: &mut H) + where + H: Hasher, + { + match self { + Expr::Array(expr) => { + hash.write_u8(0); + expr.hash(hash); + } + Expr::Assign(expr) => { + hash.write_u8(1); + expr.hash(hash); + } + Expr::AssignOp(expr) => { + hash.write_u8(2); + expr.hash(hash); + } + Expr::Async(expr) => { + hash.write_u8(3); + expr.hash(hash); + } + Expr::Await(expr) => { + hash.write_u8(4); + expr.hash(hash); + } + Expr::Binary(expr) => { + hash.write_u8(5); + expr.hash(hash); + } + Expr::Block(expr) => { + hash.write_u8(6); + expr.hash(hash); + } + Expr::Box(expr) => { + hash.write_u8(7); + expr.hash(hash); + } + Expr::Break(expr) => { + hash.write_u8(8); + expr.hash(hash); + } + Expr::Call(expr) => { + hash.write_u8(9); + expr.hash(hash); + } + Expr::Cast(expr) => { + hash.write_u8(10); + expr.hash(hash); + } + Expr::Closure(expr) => { + hash.write_u8(11); + expr.hash(hash); + } + Expr::Continue(expr) => { + hash.write_u8(12); + expr.hash(hash); + } + Expr::Field(expr) => { + hash.write_u8(13); + expr.hash(hash); + } + Expr::ForLoop(expr) => { + hash.write_u8(14); + expr.hash(hash); + } + Expr::Group(expr) => { + hash.write_u8(15); + expr.hash(hash); + } + Expr::If(expr) => { + hash.write_u8(16); + expr.hash(hash); + } + Expr::Index(expr) => { + hash.write_u8(17); + expr.hash(hash); + } + Expr::Let(expr) => { + hash.write_u8(18); + expr.hash(hash); + } + Expr::Lit(expr) => { + hash.write_u8(19); + expr.hash(hash); + } + Expr::Loop(expr) => { + hash.write_u8(20); + expr.hash(hash); + } + Expr::Macro(expr) => { + hash.write_u8(21); + expr.hash(hash); + } + Expr::Match(expr) => { + hash.write_u8(22); + expr.hash(hash); + } + Expr::MethodCall(expr) => { + hash.write_u8(23); + expr.hash(hash); + } + Expr::Paren(expr) => { + hash.write_u8(24); + expr.hash(hash); + } + Expr::Path(expr) => { + hash.write_u8(25); + expr.hash(hash); + } + Expr::Range(expr) => { + hash.write_u8(26); + expr.hash(hash); + } + Expr::Reference(expr) => { + hash.write_u8(27); + expr.hash(hash); + } + Expr::Repeat(expr) => { + hash.write_u8(28); + expr.hash(hash); + } + Expr::Return(expr) => { + hash.write_u8(29); + expr.hash(hash); + } + Expr::Struct(expr) => { + hash.write_u8(30); + expr.hash(hash); + } + Expr::Try(expr) => { + hash.write_u8(31); + expr.hash(hash); + } + Expr::TryBlock(expr) => { + hash.write_u8(32); + expr.hash(hash); + } + Expr::Tuple(expr) => { + hash.write_u8(33); + expr.hash(hash); + } + Expr::Type(expr) => { + hash.write_u8(34); + expr.hash(hash); + } + Expr::Unary(expr) => { + hash.write_u8(35); + expr.hash(hash); + } + Expr::Unsafe(expr) => { + hash.write_u8(36); + expr.hash(hash); + } + Expr::Verbatim(expr) => { + hash.write_u8(37); + TokenStreamHelper(expr).hash(hash); + } + Expr::While(expr) => { + hash.write_u8(38); + expr.hash(hash); + } + Expr::Yield(expr) => { + hash.write_u8(39); + expr.hash(hash); + } + Expr::__Nonexhaustive => unreachable!(), + } + } +} + +impl Expr { + #[cfg(all(feature = "parsing", feature = "full"))] + pub(crate) fn replace_attrs(&mut self, new: Vec<Attribute>) -> Vec<Attribute> { + match self { + Expr::Box(ExprBox { attrs, .. }) + | Expr::Array(ExprArray { attrs, .. }) + | Expr::Call(ExprCall { attrs, .. }) + | Expr::MethodCall(ExprMethodCall { attrs, .. }) + | Expr::Tuple(ExprTuple { attrs, .. }) + | Expr::Binary(ExprBinary { attrs, .. }) + | Expr::Unary(ExprUnary { attrs, .. }) + | Expr::Lit(ExprLit { attrs, .. }) + | Expr::Cast(ExprCast { attrs, .. }) + | Expr::Type(ExprType { attrs, .. }) + | Expr::Let(ExprLet { attrs, .. }) + | Expr::If(ExprIf { attrs, .. }) + | Expr::While(ExprWhile { attrs, .. }) + | Expr::ForLoop(ExprForLoop { attrs, .. }) + | Expr::Loop(ExprLoop { attrs, .. }) + | Expr::Match(ExprMatch { attrs, .. }) + | Expr::Closure(ExprClosure { attrs, .. }) + | Expr::Unsafe(ExprUnsafe { attrs, .. }) + | Expr::Block(ExprBlock { attrs, .. }) + | Expr::Assign(ExprAssign { attrs, .. }) + | Expr::AssignOp(ExprAssignOp { attrs, .. }) + | Expr::Field(ExprField { attrs, .. }) + | Expr::Index(ExprIndex { attrs, .. }) + | Expr::Range(ExprRange { attrs, .. }) + | Expr::Path(ExprPath { attrs, .. }) + | Expr::Reference(ExprReference { attrs, .. }) + | Expr::Break(ExprBreak { attrs, .. }) + | Expr::Continue(ExprContinue { attrs, .. }) + | Expr::Return(ExprReturn { attrs, .. }) + | Expr::Macro(ExprMacro { attrs, .. }) + | Expr::Struct(ExprStruct { attrs, .. }) + | Expr::Repeat(ExprRepeat { attrs, .. }) + | Expr::Paren(ExprParen { attrs, .. }) + | Expr::Group(ExprGroup { attrs, .. }) + | Expr::Try(ExprTry { attrs, .. }) + | Expr::Async(ExprAsync { attrs, .. }) + | Expr::Await(ExprAwait { attrs, .. }) + | Expr::TryBlock(ExprTryBlock { attrs, .. }) + | Expr::Yield(ExprYield { attrs, .. }) => mem::replace(attrs, new), + Expr::Verbatim(_) => Vec::new(), + Expr::__Nonexhaustive => unreachable!(), + } + } +} + +ast_enum! { + /// A struct or tuple struct field accessed in a struct literal or field + /// expression. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + #[derive(Eq, PartialEq, Hash)] + pub enum Member #manual_extra_traits { + /// A named field like `self.x`. + Named(Ident), + /// An unnamed field like `self.0`. + Unnamed(Index), + } +} + +#[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), + } + } +} + +ast_struct! { + /// The index of an unnamed tuple struct field. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + pub struct Index #manual_extra_traits { + pub index: u32, + pub span: Span, + } +} + +impl From<usize> for Index { + fn from(index: usize) -> Index { + assert!(index < u32::max_value() 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) + } +} + +#[cfg(feature = "full")] +ast_struct! { + #[derive(Default)] + pub struct Reserved { + _private: (), + } +} + +#[cfg(feature = "full")] +ast_struct! { + /// The `::<>` explicit type parameters passed to a method call: + /// `parse::<u64>()`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct MethodTurbofish { + pub colon2_token: Token![::], + pub lt_token: Token![<], + pub args: Punctuated<GenericMethodArgument, Token![,]>, + pub gt_token: Token![>], + } +} + +#[cfg(feature = "full")] +ast_enum! { + /// An individual generic argument to a method, like `T`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub enum GenericMethodArgument { + /// A type argument. + Type(Type), + /// A const expression. Must be inside of a block. + /// + /// NOTE: Identity expressions are represented as Type arguments, as + /// they are indistinguishable syntactically. + Const(Expr), + } +} + +#[cfg(feature = "full")] +ast_struct! { + /// A field-value pair in a struct literal. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct FieldValue { + /// Attributes tagged on the field. + pub attrs: Vec<Attribute>, + + /// Name or index of the field. + 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![:]>, + + /// Value of the field. + pub expr: Expr, + } +} + +#[cfg(feature = "full")] +ast_struct! { + /// A lifetime labeling a `for`, `while`, or `loop`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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 + /// # } + /// ``` + /// + /// *This type is available if Syn is built with the `"full"` feature.* + 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. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + #[cfg_attr(feature = "clone-impls", derive(Copy))] + pub enum RangeLimits { + /// Inclusive at the beginning, exclusive at the end. + HalfOpen(Token![..]), + /// Inclusive at the beginning and end. + Closed(Token![..=]), + } +} + +#[cfg(any(feature = "parsing", feature = "printing"))] +#[cfg(feature = "full")] +pub(crate) fn requires_terminator(expr: &Expr) -> bool { + // see https://github.com/rust-lang/rust/blob/eb8f2586e/src/libsyntax/parse/classify.rs#L17-L37 + match *expr { + Expr::Unsafe(..) + | Expr::Block(..) + | Expr::If(..) + | Expr::Match(..) + | Expr::While(..) + | Expr::Loop(..) + | Expr::ForLoop(..) + | Expr::Async(..) + | Expr::TryBlock(..) => false, + _ => true, + } +} + +#[cfg(feature = "parsing")] +pub(crate) mod parsing { + use super::*; + + use crate::parse::discouraged::Speculative; + use crate::parse::{Parse, ParseStream, Result}; + use crate::path; + + // 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 + #[derive(Copy, Clone)] + pub struct AllowStruct(bool); + + #[derive(Copy, Clone, PartialEq, PartialOrd)] + enum Precedence { + Any, + Assign, + Range, + Or, + And, + Compare, + BitOr, + BitXor, + BitAnd, + Shift, + Arithmetic, + Term, + Cast, + } + + impl Precedence { + fn of(op: &BinOp) -> Self { + match *op { + BinOp::Add(_) | BinOp::Sub(_) => Precedence::Arithmetic, + BinOp::Mul(_) | BinOp::Div(_) | BinOp::Rem(_) => Precedence::Term, + BinOp::And(_) => Precedence::And, + BinOp::Or(_) => Precedence::Or, + BinOp::BitXor(_) => Precedence::BitXor, + BinOp::BitAnd(_) => Precedence::BitAnd, + BinOp::BitOr(_) => Precedence::BitOr, + BinOp::Shl(_) | BinOp::Shr(_) => Precedence::Shift, + BinOp::Eq(_) + | BinOp::Lt(_) + | BinOp::Le(_) + | BinOp::Ne(_) + | BinOp::Ge(_) + | BinOp::Gt(_) => Precedence::Compare, + BinOp::AddEq(_) + | BinOp::SubEq(_) + | BinOp::MulEq(_) + | BinOp::DivEq(_) + | BinOp::RemEq(_) + | BinOp::BitXorEq(_) + | BinOp::BitAndEq(_) + | BinOp::BitOrEq(_) + | BinOp::ShlEq(_) + | BinOp::ShrEq(_) => Precedence::Assign, + } + } + } + + impl Parse for Expr { + fn parse(input: ParseStream) -> Result<Self> { + ambiguous_expr(input, AllowStruct(true)) + } + } + + #[cfg(feature = "full")] + fn expr_no_struct(input: ParseStream) -> Result<Expr> { + ambiguous_expr(input, AllowStruct(false)) + } + + #[cfg(feature = "full")] + fn parse_expr( + input: ParseStream, + mut lhs: Expr, + allow_struct: AllowStruct, + base: Precedence, + ) -> Result<Expr> { + loop { + if input + .fork() + .parse::<BinOp>() + .ok() + .map_or(false, |op| Precedence::of(&op) >= base) + { + let op: BinOp = input.parse()?; + let precedence = Precedence::of(&op); + let mut rhs = unary_expr(input, allow_struct)?; + loop { + let next = peek_precedence(input); + if next > precedence || next == precedence && precedence == Precedence::Assign { + rhs = parse_expr(input, rhs, allow_struct, next)?; + } else { + break; + } + } + lhs = if precedence == Precedence::Assign { + Expr::AssignOp(ExprAssignOp { + attrs: Vec::new(), + left: Box::new(lhs), + op, + right: Box::new(rhs), + }) + } else { + Expr::Binary(ExprBinary { + attrs: Vec::new(), + left: Box::new(lhs), + op, + right: Box::new(rhs), + }) + }; + } else if Precedence::Assign >= base + && input.peek(Token![=]) + && !input.peek(Token![==]) + && !input.peek(Token![=>]) + { + let eq_token: Token![=] = input.parse()?; + let mut rhs = unary_expr(input, allow_struct)?; + loop { + let next = peek_precedence(input); + if next >= Precedence::Assign { + rhs = parse_expr(input, rhs, allow_struct, next)?; + } else { + break; + } + } + lhs = Expr::Assign(ExprAssign { + attrs: Vec::new(), + left: Box::new(lhs), + eq_token, + right: Box::new(rhs), + }); + } else if Precedence::Range >= base && input.peek(Token![..]) { + let limits: RangeLimits = input.parse()?; + let rhs = if input.is_empty() + || input.peek(Token![,]) + || input.peek(Token![;]) + || !allow_struct.0 && input.peek(token::Brace) + { + None + } else { + let mut rhs = unary_expr(input, allow_struct)?; + loop { + let next = peek_precedence(input); + if next > Precedence::Range { + rhs = parse_expr(input, rhs, allow_struct, next)?; + } else { + break; + } + } + Some(rhs) + }; + lhs = Expr::Range(ExprRange { + attrs: Vec::new(), + from: Some(Box::new(lhs)), + limits, + to: rhs.map(Box::new), + }); + } else if Precedence::Cast >= base && input.peek(Token![as]) { + let as_token: Token![as] = input.parse()?; + let ty = input.call(Type::without_plus)?; + lhs = Expr::Cast(ExprCast { + attrs: Vec::new(), + expr: Box::new(lhs), + as_token, + ty: Box::new(ty), + }); + } else if Precedence::Cast >= base && input.peek(Token![:]) && !input.peek(Token![::]) { + let colon_token: Token![:] = input.parse()?; + let ty = input.call(Type::without_plus)?; + lhs = Expr::Type(ExprType { + attrs: Vec::new(), + expr: Box::new(lhs), + colon_token, + ty: Box::new(ty), + }); + } else { + break; + } + } + Ok(lhs) + } + + #[cfg(not(feature = "full"))] + fn parse_expr( + input: ParseStream, + mut lhs: Expr, + allow_struct: AllowStruct, + base: Precedence, + ) -> Result<Expr> { + loop { + if input + .fork() + .parse::<BinOp>() + .ok() + .map_or(false, |op| Precedence::of(&op) >= base) + { + let op: BinOp = input.parse()?; + let precedence = Precedence::of(&op); + let mut rhs = unary_expr(input, allow_struct)?; + loop { + let next = peek_precedence(input); + if next > precedence || next == precedence && precedence == Precedence::Assign { + rhs = parse_expr(input, rhs, allow_struct, next)?; + } else { + break; + } + } + lhs = Expr::Binary(ExprBinary { + attrs: Vec::new(), + left: Box::new(lhs), + op, + right: Box::new(rhs), + }); + } else if Precedence::Cast >= base && input.peek(Token![as]) { + let as_token: Token![as] = input.parse()?; + let ty = input.call(Type::without_plus)?; + lhs = Expr::Cast(ExprCast { + attrs: Vec::new(), + expr: Box::new(lhs), + as_token, + ty: Box::new(ty), + }); + } else { + break; + } + } + Ok(lhs) + } + + fn peek_precedence(input: ParseStream) -> Precedence { + if let Ok(op) = input.fork().parse() { + Precedence::of(&op) + } else if input.peek(Token![=]) && !input.peek(Token![=>]) { + Precedence::Assign + } else if input.peek(Token![..]) { + Precedence::Range + } else if input.peek(Token![as]) || input.peek(Token![:]) && !input.peek(Token![::]) { + Precedence::Cast + } else { + Precedence::Any + } + } + + // Parse an arbitrary expression. + fn ambiguous_expr(input: ParseStream, allow_struct: AllowStruct) -> Result<Expr> { + let lhs = unary_expr(input, allow_struct)?; + parse_expr(input, lhs, allow_struct, Precedence::Any) + } + + // <UnOp> <trailer> + // & <trailer> + // &mut <trailer> + // box <trailer> + #[cfg(feature = "full")] + fn unary_expr(input: ParseStream, allow_struct: AllowStruct) -> Result<Expr> { + let ahead = input.fork(); + let attrs = ahead.call(Attribute::parse_outer)?; + if ahead.peek(Token![&]) + || ahead.peek(Token![box]) + || ahead.peek(Token![*]) + || ahead.peek(Token![!]) + || ahead.peek(Token![-]) + { + input.advance_to(&ahead); + if input.peek(Token![&]) { + Ok(Expr::Reference(ExprReference { + attrs, + and_token: input.parse()?, + raw: Reserved::default(), + mutability: input.parse()?, + expr: Box::new(unary_expr(input, allow_struct)?), + })) + } else if input.peek(Token![box]) { + Ok(Expr::Box(ExprBox { + attrs, + box_token: input.parse()?, + expr: Box::new(unary_expr(input, allow_struct)?), + })) + } else { + Ok(Expr::Unary(ExprUnary { + attrs, + op: input.parse()?, + expr: Box::new(unary_expr(input, allow_struct)?), + })) + } + } else { + trailer_expr(input, allow_struct) + } + } + + #[cfg(not(feature = "full"))] + fn unary_expr(input: ParseStream, allow_struct: AllowStruct) -> Result<Expr> { + let ahead = input.fork(); + let attrs = ahead.call(Attribute::parse_outer)?; + if ahead.peek(Token![*]) || ahead.peek(Token![!]) || ahead.peek(Token![-]) { + input.advance_to(&ahead); + Ok(Expr::Unary(ExprUnary { + attrs, + op: input.parse()?, + expr: Box::new(unary_expr(input, allow_struct)?), + })) + } else { + trailer_expr(input, allow_struct) + } + } + + // <atom> (..<args>) ... + // <atom> . <ident> (..<args>) ... + // <atom> . <ident> ... + // <atom> . <lit> ... + // <atom> [ <expr> ] ... + // <atom> ? ... + #[cfg(feature = "full")] + fn trailer_expr(input: ParseStream, allow_struct: AllowStruct) -> Result<Expr> { + if input.peek(token::Group) { + return input.call(expr_group).map(Expr::Group); + } + + let outer_attrs = input.call(Attribute::parse_outer)?; + + let atom = atom_expr(input, allow_struct)?; + let mut e = trailer_helper(input, atom)?; + + let inner_attrs = e.replace_attrs(Vec::new()); + let attrs = private::attrs(outer_attrs, 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)?, + }); + } else if input.peek(Token![.]) && !input.peek(Token![..]) { + let dot_token: Token![.] = input.parse()?; + + if input.peek(token::Await) { + e = Expr::Await(ExprAwait { + attrs: Vec::new(), + base: Box::new(e), + dot_token, + await_token: input.parse()?, + }); + continue; + } + + let member: Member = input.parse()?; + let turbofish = if member.is_named() && input.peek(Token![::]) { + Some(MethodTurbofish { + colon2_token: input.parse()?, + lt_token: input.parse()?, + args: { + let mut args = Punctuated::new(); + loop { + if input.peek(Token![>]) { + break; + } + let value = input.call(generic_method_argument)?; + args.push_value(value); + if input.peek(Token![>]) { + break; + } + let punct = input.parse()?; + args.push_punct(punct); + } + args + }, + gt_token: input.parse()?, + }) + } 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)?, + }); + 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![?]) { + 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, allow_struct: AllowStruct) -> Result<Expr> { + let mut e = atom_expr(input, allow_struct)?; + + 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)?, + }); + } else if input.peek(Token![.]) && !input.peek(Token![..]) && !input.peek2(token::Await) + { + e = Expr::Field(ExprField { + attrs: Vec::new(), + base: Box::new(e), + dot_token: input.parse()?, + member: input.parse()?, + }); + } 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) { + input.call(expr_group).map(Expr::Group) + } 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.call(expr_async).map(Expr::Async) + } else if input.peek(Token![try]) && input.peek2(token::Brace) { + input.call(expr_try_block).map(Expr::TryBlock) + } else if input.peek(Token![|]) + || input.peek(Token![async]) && (input.peek2(Token![|]) || input.peek2(Token![move])) + || input.peek(Token![static]) + || input.peek(Token![move]) + { + expr_closure(input, allow_struct).map(Expr::Closure) + } 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![extern]) + || input.peek(Token![crate]) + { + 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.call(expr_continue).map(Expr::Continue) + } else if input.peek(Token![return]) { + expr_ret(input, allow_struct).map(Expr::Return) + } else if input.peek(token::Bracket) { + array_or_repeat(input) + } else if input.peek(Token![let]) { + input.call(expr_let).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.call(expr_yield).map(Expr::Yield) + } else if input.peek(Token![unsafe]) { + input.call(expr_unsafe).map(Expr::Unsafe) + } else if input.peek(token::Brace) { + input.call(expr_block).map(Expr::Block) + } else if input.peek(Token![..]) { + expr_range(input, allow_struct).map(Expr::Range) + } else if input.peek(Lifetime) { + 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.call(expr_block)?) + } 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) + } else { + Err(input.error("expected expression")) + } + } + + #[cfg(not(feature = "full"))] + fn atom_expr(input: ParseStream, _allow_struct: AllowStruct) -> Result<Expr> { + if input.peek(Lit) { + input.parse().map(Expr::Lit) + } else if input.peek(token::Paren) { + input.call(expr_paren).map(Expr::Paren) + } 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![extern]) + || input.peek(Token![crate]) + { + input.parse().map(Expr::Path) + } else { + Err(input.error("unsupported expression; enable syn's features=[\"full\"]")) + } + } + + #[cfg(feature = "full")] + fn path_or_macro_or_struct(input: ParseStream, allow_struct: AllowStruct) -> Result<Expr> { + let expr: ExprPath = input.parse()?; + if expr.qself.is_some() { + return Ok(Expr::Path(expr)); + } + + if input.peek(Token![!]) && !input.peek(Token![!=]) { + let mut contains_arguments = false; + for segment in &expr.path.segments { + match segment.arguments { + PathArguments::None => {} + PathArguments::AngleBracketed(_) | PathArguments::Parenthesized(_) => { + contains_arguments = true; + } + } + } + + if !contains_arguments { + let bang_token: Token![!] = input.parse()?; + let (delimiter, tokens) = mac::parse_delimiter(input)?; + return Ok(Expr::Macro(ExprMacro { + attrs: Vec::new(), + mac: Macro { + path: expr.path, + bang_token, + delimiter, + tokens, + }, + })); + } + } + + if allow_struct.0 && input.peek(token::Brace) { + let outer_attrs = Vec::new(); + expr_struct_helper(input, outer_attrs, expr.path).map(Expr::Struct) + } else { + Ok(Expr::Path(expr)) + } + } + + #[cfg(feature = "full")] + fn paren_or_tuple(input: ParseStream) -> Result<Expr> { + let content; + let paren_token = parenthesized!(content in input); + let inner_attrs = content.call(Attribute::parse_inner)?; + if content.is_empty() { + return Ok(Expr::Tuple(ExprTuple { + attrs: inner_attrs, + paren_token, + elems: Punctuated::new(), + })); + } + + let first: Expr = content.parse()?; + if content.is_empty() { + return Ok(Expr::Paren(ExprParen { + attrs: inner_attrs, + 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: inner_attrs, + paren_token, + elems, + })) + } + + #[cfg(feature = "full")] + fn array_or_repeat(input: ParseStream) -> Result<Expr> { + let content; + let bracket_token = bracketed!(content in input); + let inner_attrs = content.call(Attribute::parse_inner)?; + if content.is_empty() { + return Ok(Expr::Array(ExprArray { + attrs: inner_attrs, + 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: inner_attrs, + bracket_token, + elems, + })) + } else if content.peek(Token![;]) { + let semi_token: Token![;] = content.parse()?; + let len: Expr = content.parse()?; + Ok(Expr::Repeat(ExprRepeat { + attrs: inner_attrs, + bracket_token, + expr: Box::new(first), + semi_token, + len: Box::new(len), + })) + } else { + Err(content.error("expected `,` or `;`")) + } + } + + #[cfg(feature = "full")] + pub(crate) fn expr_early(input: ParseStream) -> Result<Expr> { + let mut attrs = input.call(Attribute::parse_outer)?; + let mut expr = 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]) { + 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.call(expr_try_block)?) + } else if input.peek(Token![unsafe]) { + Expr::Unsafe(input.call(expr_unsafe)?) + } else if input.peek(token::Brace) { + Expr::Block(input.call(expr_block)?) + } else { + let allow_struct = AllowStruct(true); + let mut expr = unary_expr(input, allow_struct)?; + + attrs.extend(expr.replace_attrs(Vec::new())); + expr.replace_attrs(attrs); + + return parse_expr(input, expr, allow_struct, Precedence::Any); + }; + + if 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::Any); + } + + attrs.extend(expr.replace_attrs(Vec::new())); + expr.replace_attrs(attrs); + Ok(expr) + } + + impl Parse for ExprLit { + fn parse(input: ParseStream) -> Result<Self> { + Ok(ExprLit { + attrs: Vec::new(), + lit: input.parse()?, + }) + } + } + + #[cfg(feature = "full")] + fn expr_group(input: ParseStream) -> Result<ExprGroup> { + let group = crate::group::parse_group(input)?; + Ok(ExprGroup { + attrs: Vec::new(), + group_token: group.token, + expr: group.content.parse()?, + }) + } + + #[cfg(not(feature = "full"))] + fn expr_paren(input: ParseStream) -> Result<ExprParen> { + let content; + Ok(ExprParen { + attrs: Vec::new(), + paren_token: parenthesized!(content in input), + expr: content.parse()?, + }) + } + + #[cfg(feature = "full")] + fn generic_method_argument(input: ParseStream) -> Result<GenericMethodArgument> { + // TODO parse const generics as well + input.parse().map(GenericMethodArgument::Type) + } + + #[cfg(feature = "full")] + fn expr_let(input: ParseStream) -> Result<ExprLet> { + Ok(ExprLet { + attrs: Vec::new(), + let_token: input.parse()?, + pat: { + let leading_vert: Option<Token![|]> = input.parse()?; + let pat: Pat = input.parse()?; + if leading_vert.is_some() + || input.peek(Token![|]) && !input.peek(Token![||]) && !input.peek(Token![|=]) + { + let mut cases = Punctuated::new(); + cases.push_value(pat); + while input.peek(Token![|]) + && !input.peek(Token![||]) + && !input.peek(Token![|=]) + { + let punct = input.parse()?; + cases.push_punct(punct); + let pat: Pat = input.parse()?; + cases.push_value(pat); + } + Pat::Or(PatOr { + attrs: Vec::new(), + leading_vert, + cases, + }) + } else { + pat + } + }, + eq_token: input.parse()?, + expr: Box::new(input.call(expr_no_struct)?), + }) + } + + #[cfg(feature = "full")] + impl Parse for ExprIf { + fn parse(input: ParseStream) -> Result<Self> { + Ok(ExprIf { + attrs: Vec::new(), + if_token: input.parse()?, + cond: Box::new(input.call(expr_no_struct)?), + then_branch: input.parse()?, + else_branch: { + if input.peek(Token![else]) { + Some(input.call(else_block)?) + } else { + None + } + }, + }) + } + } + + #[cfg(feature = "full")] + fn else_block(input: ParseStream) -> Result<(Token![else], Box<Expr>)> { + let else_token: Token![else] = input.parse()?; + + let lookahead = input.lookahead1(); + let else_branch = if input.peek(Token![if]) { + input.parse().map(Expr::If)? + } else if input.peek(token::Brace) { + Expr::Block(ExprBlock { + attrs: Vec::new(), + label: None, + block: input.parse()?, + }) + } else { + return Err(lookahead.error()); + }; + + Ok((else_token, Box::new(else_branch))) + } + + #[cfg(feature = "full")] + impl Parse for ExprForLoop { + fn parse(input: ParseStream) -> Result<Self> { + let label: Option<Label> = input.parse()?; + let for_token: Token![for] = input.parse()?; + + let leading_vert: Option<Token![|]> = input.parse()?; + let mut pat: Pat = input.parse()?; + if leading_vert.is_some() || input.peek(Token![|]) { + let mut cases = Punctuated::new(); + cases.push_value(pat); + while input.peek(Token![|]) { + let punct = input.parse()?; + cases.push_punct(punct); + let pat: Pat = input.parse()?; + cases.push_value(pat); + } + pat = Pat::Or(PatOr { + attrs: Vec::new(), + leading_vert, + cases, + }); + } + + let in_token: Token![in] = input.parse()?; + let expr: Expr = input.call(expr_no_struct)?; + + 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(ExprForLoop { + attrs: inner_attrs, + label, + for_token, + pat, + in_token, + expr: Box::new(expr), + body: Block { brace_token, stmts }, + }) + } + } + + #[cfg(feature = "full")] + impl Parse for ExprLoop { + fn parse(input: ParseStream) -> Result<Self> { + let label: Option<Label> = input.parse()?; + let loop_token: Token![loop] = 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(ExprLoop { + attrs: inner_attrs, + label, + loop_token, + body: Block { brace_token, stmts }, + }) + } + } + + #[cfg(feature = "full")] + impl Parse for ExprMatch { + fn parse(input: ParseStream) -> Result<Self> { + let match_token: Token![match] = input.parse()?; + let expr = expr_no_struct(input)?; + + let content; + let brace_token = braced!(content in input); + let inner_attrs = content.call(Attribute::parse_inner)?; + + let mut arms = Vec::new(); + while !content.is_empty() { + arms.push(content.call(Arm::parse)?); + } + + Ok(ExprMatch { + attrs: inner_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"))] + 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! { + ExprBox, Box, "expected box expression", + ExprArray, Array, "expected slice literal expression", + ExprCall, Call, "expected function call expression", + ExprMethodCall, MethodCall, "expected method call expression", + ExprTuple, Tuple, "expected tuple expression", + ExprBinary, Binary, "expected binary operation", + ExprUnary, Unary, "expected unary operation", + ExprCast, Cast, "expected cast expression", + ExprType, Type, "expected type ascription expression", + ExprLet, Let, "expected let guard", + ExprClosure, Closure, "expected closure expression", + ExprUnsafe, Unsafe, "expected unsafe block", + ExprBlock, Block, "expected blocked scope", + ExprAssign, Assign, "expected assignment expression", + ExprAssignOp, AssignOp, "expected compound assignment expression", + ExprField, Field, "expected struct field access", + ExprIndex, Index, "expected indexing expression", + ExprRange, Range, "expected range expression", + ExprReference, Reference, "expected referencing operation", + ExprBreak, Break, "expected break expression", + ExprContinue, Continue, "expected continue expression", + ExprReturn, Return, "expected return expression", + ExprMacro, Macro, "expected macro invocation expression", + ExprStruct, Struct, "expected struct literal expression", + ExprRepeat, Repeat, "expected array literal constructed from one repeated element", + ExprParen, Paren, "expected parenthesized expression", + ExprTry, Try, "expected try expression", + ExprAsync, Async, "expected async block", + ExprTryBlock, TryBlock, "expected try block", + ExprYield, Yield, "expected yield expression", + } + + #[cfg(feature = "full")] + fn expr_try_block(input: ParseStream) -> Result<ExprTryBlock> { + Ok(ExprTryBlock { + attrs: Vec::new(), + try_token: input.parse()?, + block: input.parse()?, + }) + } + + #[cfg(feature = "full")] + fn expr_yield(input: ParseStream) -> Result<ExprYield> { + Ok(ExprYield { + attrs: Vec::new(), + yield_token: input.parse()?, + expr: { + if !input.is_empty() && !input.peek(Token![,]) && !input.peek(Token![;]) { + Some(input.parse()?) + } else { + None + } + }, + }) + } + + #[cfg(feature = "full")] + fn expr_closure(input: ParseStream, allow_struct: AllowStruct) -> Result<ExprClosure> { + let asyncness: Option<Token![async]> = input.parse()?; + let movability: Option<Token![static]> = if asyncness.is_none() { + input.parse()? + } else { + None + }; + 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(), + asyncness, + movability, + capture, + or1_token, + inputs, + or2_token, + output, + body: Box::new(body), + }) + } + + #[cfg(feature = "full")] + fn expr_async(input: ParseStream) -> Result<ExprAsync> { + 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 = input.parse()?; + + 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::Box(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::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, + Pat::__Nonexhaustive => unreachable!(), + } + Ok(pat) + } + } + + #[cfg(feature = "full")] + impl Parse for ExprWhile { + fn parse(input: ParseStream) -> Result<Self> { + let label: Option<Label> = input.parse()?; + let while_token: Token![while] = input.parse()?; + let cond = expr_no_struct(input)?; + + 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(ExprWhile { + attrs: inner_attrs, + label, + while_token, + cond: Box::new(cond), + body: Block { brace_token, stmts }, + }) + } + } + + #[cfg(feature = "full")] + impl Parse for Label { + fn parse(input: ParseStream) -> Result<Self> { + Ok(Label { + name: input.parse()?, + colon_token: input.parse()?, + }) + } + } + + #[cfg(feature = "full")] + 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")] + fn expr_continue(input: ParseStream) -> Result<ExprContinue> { + 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> { + Ok(ExprBreak { + attrs: Vec::new(), + break_token: input.parse()?, + label: input.parse()?, + expr: { + if input.is_empty() + || input.peek(Token![,]) + || input.peek(Token![;]) + || !allow_struct.0 && input.peek(token::Brace) + { + None + } else { + let expr = ambiguous_expr(input, allow_struct)?; + Some(Box::new(expr)) + } + }, + }) + } + + #[cfg(feature = "full")] + fn expr_ret(input: ParseStream, allow_struct: AllowStruct) -> Result<ExprReturn> { + Ok(ExprReturn { + attrs: Vec::new(), + return_token: input.parse()?, + expr: { + if input.is_empty() || input.peek(Token![,]) || input.peek(Token![;]) { + None + } else { + // NOTE: return is greedy and eats blocks after it even when in a + // position where structs are not allowed, such as in if statement + // conditions. For example: + // + // if return { println!("A") } {} // Prints "A" + let expr = ambiguous_expr(input, allow_struct)?; + Some(Box::new(expr)) + } + }, + }) + } + + #[cfg(feature = "full")] + 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(feature = "full")] + fn expr_struct_helper( + input: ParseStream, + outer_attrs: Vec<Attribute>, + path: Path, + ) -> Result<ExprStruct> { + let content; + let brace_token = braced!(content in input); + let inner_attrs = content.call(Attribute::parse_inner)?; + let attrs = private::attrs(outer_attrs, inner_attrs); + + let mut fields = Punctuated::new(); + while !content.is_empty() { + if content.peek(Token![..]) { + return Ok(ExprStruct { + attrs, + brace_token, + path, + fields, + dot2_token: Some(content.parse()?), + rest: Some(Box::new(content.parse()?)), + }); + } + + fields.push(content.parse()?); + if !content.peek(Token![,]) { + break; + } + let punct: Token![,] = content.parse()?; + fields.push_punct(punct); + } + + Ok(ExprStruct { + attrs, + brace_token, + path, + fields, + dot2_token: None, + rest: None, + }) + } + + #[cfg(feature = "full")] + fn expr_unsafe(input: ParseStream) -> Result<ExprUnsafe> { + 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")] + pub fn expr_block(input: ParseStream) -> Result<ExprBlock> { + let label: Option<Label> = 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(ExprBlock { + attrs: inner_attrs, + label, + block: Block { brace_token, stmts }, + }) + } + + #[cfg(feature = "full")] + fn expr_range(input: ParseStream, allow_struct: AllowStruct) -> Result<ExprRange> { + Ok(ExprRange { + attrs: Vec::new(), + from: None, + limits: input.parse()?, + to: { + if input.is_empty() + || input.peek(Token![,]) + || input.peek(Token![;]) + || !allow_struct.0 && input.peek(token::Brace) + { + None + } else { + let to = ambiguous_expr(input, allow_struct)?; + Some(Box::new(to)) + } + }, + }) + } + + #[cfg(feature = "full")] + impl Parse for RangeLimits { + fn parse(input: ParseStream) -> Result<Self> { + let lookahead = input.lookahead1(); + if lookahead.peek(Token![..=]) { + input.parse().map(RangeLimits::Closed) + } else if lookahead.peek(Token![...]) { + let dot3: Token![...] = input.parse()?; + Ok(RangeLimits::Closed(Token)) + } else if lookahead.peek(Token![..]) { + input.parse().map(RangeLimits::HalfOpen) + } else { + Err(lookahead.error()) + } + } + } + + 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 (qself, path) = path::parsing::qpath(input, true)?; + + Ok(ExprPath { attrs, qself, path }) + } + } + + 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 Parse for Arm { + fn parse(input: ParseStream) -> Result<Arm> { + let requires_comma; + Ok(Arm { + attrs: input.call(Attribute::parse_outer)?, + pat: { + let leading_vert: Option<Token![|]> = input.parse()?; + let pat: Pat = input.parse()?; + if leading_vert.is_some() || input.peek(Token![|]) { + let mut cases = Punctuated::new(); + cases.push_value(pat); + while input.peek(Token![|]) { + let punct = input.parse()?; + cases.push_punct(punct); + let pat: Pat = input.parse()?; + cases.push_value(pat); + } + Pat::Or(PatOr { + attrs: Vec::new(), + leading_vert, + cases, + }) + } else { + pat + } + }, + 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 = input.call(expr_early)?; + requires_comma = requires_terminator(&body); + Box::new(body) + }, + comma: { + if requires_comma && !input.is_empty() { + Some(input.parse()?) + } else { + input.parse()? + } + }, + }) + } + } + + 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")) + } + } + } + + #[cfg(feature = "full")] + impl Member { + fn is_named(&self) -> bool { + match *self { + Member::Named(_) => true, + Member::Unnamed(_) => false, + } + } + } +} + +#[cfg(feature = "printing")] +pub(crate) mod printing { + use super::*; + + use proc_macro2::{Literal, TokenStream}; + use quote::{ToTokens, TokenStreamExt}; + + #[cfg(feature = "full")] + use crate::attr::FilterAttrs; + #[cfg(feature = "full")] + use crate::print::TokensOrDefault; + + // If the given expression is a bare `ExprStruct`, wraps it in parenthesis + // before appending it to `TokenStream`. + #[cfg(feature = "full")] + fn wrap_bare_struct(tokens: &mut TokenStream, e: &Expr) { + if let Expr::Struct(_) = *e { + token::Paren::default().surround(tokens, |tokens| { + e.to_tokens(tokens); + }); + } else { + e.to_tokens(tokens); + } + } + + #[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) {} + + #[cfg(not(feature = "full"))] + fn inner_attrs_to_tokens(_attrs: &[Attribute], _tokens: &mut TokenStream) {} + + #[cfg(feature = "full")] + impl ToTokens for ExprBox { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.box_token.to_tokens(tokens); + self.expr.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + impl ToTokens for ExprArray { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.bracket_token.surround(tokens, |tokens| { + inner_attrs_to_tokens(&self.attrs, tokens); + self.elems.to_tokens(tokens); + }) + } + } + + impl ToTokens for ExprCall { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.func.to_tokens(tokens); + self.paren_token.surround(tokens, |tokens| { + self.args.to_tokens(tokens); + }) + } + } + + #[cfg(feature = "full")] + impl ToTokens for ExprMethodCall { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.receiver.to_tokens(tokens); + self.dot_token.to_tokens(tokens); + self.method.to_tokens(tokens); + self.turbofish.to_tokens(tokens); + self.paren_token.surround(tokens, |tokens| { + self.args.to_tokens(tokens); + }); + } + } + + #[cfg(feature = "full")] + impl ToTokens for MethodTurbofish { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.colon2_token.to_tokens(tokens); + self.lt_token.to_tokens(tokens); + self.args.to_tokens(tokens); + self.gt_token.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + impl ToTokens for GenericMethodArgument { + fn to_tokens(&self, tokens: &mut TokenStream) { + match self { + GenericMethodArgument::Type(t) => t.to_tokens(tokens), + GenericMethodArgument::Const(c) => c.to_tokens(tokens), + } + } + } + + #[cfg(feature = "full")] + impl ToTokens for ExprTuple { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.paren_token.surround(tokens, |tokens| { + inner_attrs_to_tokens(&self.attrs, 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); + } + }) + } + } + + impl ToTokens for ExprBinary { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.left.to_tokens(tokens); + self.op.to_tokens(tokens); + self.right.to_tokens(tokens); + } + } + + impl ToTokens for ExprUnary { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.op.to_tokens(tokens); + self.expr.to_tokens(tokens); + } + } + + impl ToTokens for ExprLit { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.lit.to_tokens(tokens); + } + } + + impl ToTokens for ExprCast { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.expr.to_tokens(tokens); + self.as_token.to_tokens(tokens); + self.ty.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + impl ToTokens for ExprType { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.expr.to_tokens(tokens); + self.colon_token.to_tokens(tokens); + self.ty.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + fn maybe_wrap_else(tokens: &mut TokenStream, else_: &Option<(Token![else], Box<Expr>)>) { + if let Some((else_token, else_)) = else_ { + else_token.to_tokens(tokens); + + // If we are not one of the valid expressions to exist in an else + // clause, wrap ourselves in a block. + match **else_ { + Expr::If(_) | Expr::Block(_) => { + else_.to_tokens(tokens); + } + _ => { + token::Brace::default().surround(tokens, |tokens| { + else_.to_tokens(tokens); + }); + } + } + } + } + + #[cfg(feature = "full")] + impl ToTokens for ExprLet { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.let_token.to_tokens(tokens); + self.pat.to_tokens(tokens); + self.eq_token.to_tokens(tokens); + wrap_bare_struct(tokens, &self.expr); + } + } + + #[cfg(feature = "full")] + impl ToTokens for ExprIf { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.if_token.to_tokens(tokens); + wrap_bare_struct(tokens, &self.cond); + self.then_branch.to_tokens(tokens); + maybe_wrap_else(tokens, &self.else_branch); + } + } + + #[cfg(feature = "full")] + 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); + wrap_bare_struct(tokens, &self.cond); + self.body.brace_token.surround(tokens, |tokens| { + inner_attrs_to_tokens(&self.attrs, tokens); + tokens.append_all(&self.body.stmts); + }); + } + } + + #[cfg(feature = "full")] + 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); + wrap_bare_struct(tokens, &self.expr); + self.body.brace_token.surround(tokens, |tokens| { + inner_attrs_to_tokens(&self.attrs, tokens); + tokens.append_all(&self.body.stmts); + }); + } + } + + #[cfg(feature = "full")] + 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(feature = "full")] + impl ToTokens for ExprMatch { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.match_token.to_tokens(tokens); + wrap_bare_struct(tokens, &self.expr); + 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 && requires_terminator(&arm.body) && arm.comma.is_none() { + <Token![,]>::default().to_tokens(tokens); + } + } + }); + } + } + + #[cfg(feature = "full")] + 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")] + impl ToTokens for ExprAwait { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.base.to_tokens(tokens); + self.dot_token.to_tokens(tokens); + self.await_token.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + 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(feature = "full")] + impl ToTokens for ExprYield { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.yield_token.to_tokens(tokens); + self.expr.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + impl ToTokens for ExprClosure { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.asyncness.to_tokens(tokens); + self.movability.to_tokens(tokens); + self.capture.to_tokens(tokens); + self.or1_token.to_tokens(tokens); + self.inputs.to_tokens(tokens); + self.or2_token.to_tokens(tokens); + self.output.to_tokens(tokens); + self.body.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + 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")] + 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")] + impl ToTokens for ExprAssign { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.left.to_tokens(tokens); + self.eq_token.to_tokens(tokens); + self.right.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + impl ToTokens for ExprAssignOp { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.left.to_tokens(tokens); + self.op.to_tokens(tokens); + self.right.to_tokens(tokens); + } + } + + impl ToTokens for ExprField { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.base.to_tokens(tokens); + self.dot_token.to_tokens(tokens); + self.member.to_tokens(tokens); + } + } + + 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), + } + } + } + + 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); + } + } + + impl ToTokens for ExprIndex { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.expr.to_tokens(tokens); + self.bracket_token.surround(tokens, |tokens| { + self.index.to_tokens(tokens); + }); + } + } + + #[cfg(feature = "full")] + impl ToTokens for ExprRange { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.from.to_tokens(tokens); + match &self.limits { + RangeLimits::HalfOpen(t) => t.to_tokens(tokens), + RangeLimits::Closed(t) => t.to_tokens(tokens), + } + self.to.to_tokens(tokens); + } + } + + impl ToTokens for ExprPath { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + private::print_path(tokens, &self.qself, &self.path); + } + } + + #[cfg(feature = "full")] + impl ToTokens for ExprReference { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.and_token.to_tokens(tokens); + self.mutability.to_tokens(tokens); + self.expr.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + impl ToTokens for ExprBreak { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.break_token.to_tokens(tokens); + self.label.to_tokens(tokens); + self.expr.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + 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(feature = "full")] + impl ToTokens for ExprReturn { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.return_token.to_tokens(tokens); + self.expr.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + 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")] + impl ToTokens for ExprStruct { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.path.to_tokens(tokens); + self.brace_token.surround(tokens, |tokens| { + inner_attrs_to_tokens(&self.attrs, tokens); + self.fields.to_tokens(tokens); + if self.rest.is_some() { + TokensOrDefault(&self.dot2_token).to_tokens(tokens); + self.rest.to_tokens(tokens); + } + }) + } + } + + #[cfg(feature = "full")] + impl ToTokens for ExprRepeat { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.bracket_token.surround(tokens, |tokens| { + inner_attrs_to_tokens(&self.attrs, tokens); + self.expr.to_tokens(tokens); + self.semi_token.to_tokens(tokens); + self.len.to_tokens(tokens); + }) + } + } + + #[cfg(feature = "full")] + 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); + }); + } + } + + impl ToTokens for ExprParen { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.paren_token.surround(tokens, |tokens| { + inner_attrs_to_tokens(&self.attrs, tokens); + self.expr.to_tokens(tokens); + }); + } + } + + #[cfg(feature = "full")] + impl ToTokens for ExprTry { + fn to_tokens(&self, tokens: &mut TokenStream) { + outer_attrs_to_tokens(&self.attrs, tokens); + self.expr.to_tokens(tokens); + self.question_token.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + impl ToTokens for Label { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.name.to_tokens(tokens); + self.colon_token.to_tokens(tokens); + } + } + + #[cfg(feature = "full")] + 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(feature = "full")] + 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); + self.body.to_tokens(tokens); + self.comma.to_tokens(tokens); + } + } +} |