Enum rustc_ast::ast::ExprKind

pub enum ExprKind {
    Box(P<Expr>),
    Array(Vec<P<Expr>>),
    ConstBlock(AnonConst),
    Call(P<Expr>, Vec<P<Expr>>),
    MethodCall(PathSegment, Vec<P<Expr>>, Span),
    Tup(Vec<P<Expr>>),
    Binary(BinOp, P<Expr>, P<Expr>),
    Unary(UnOp, P<Expr>),
    Lit(Lit),
    Cast(P<Expr>, P<Ty>),
    Type(P<Expr>, P<Ty>),
    Let(P<Pat>, P<Expr>),
    If(P<Expr>, P<Block>, Option<P<Expr>>),
    While(P<Expr>, P<Block>, Option<Label>),
    ForLoop(P<Pat>, P<Expr>, P<Block>, Option<Label>),
    Loop(P<Block>, Option<Label>),
    Match(P<Expr>, Vec<Arm>),
    Closure(CaptureBy, Async, Movability, P<FnDecl>, P<Expr>, Span),
    Block(P<Block>, Option<Label>),
    Async(CaptureBy, NodeId, P<Block>),
    Await(P<Expr>),
    TryBlock(P<Block>),
    Assign(P<Expr>, P<Expr>, Span),
    AssignOp(BinOp, P<Expr>, P<Expr>),
    Field(P<Expr>, Ident),
    Index(P<Expr>, P<Expr>),
    Range(Option<P<Expr>>, Option<P<Expr>>, RangeLimits),
    Underscore,
    Path(Option<QSelf>, Path),
    AddrOf(BorrowKind, Mutability, P<Expr>),
    Break(Option<Label>, Option<P<Expr>>),
    Continue(Option<Label>),
    Ret(Option<P<Expr>>),
    InlineAsm(P<InlineAsm>),
    LlvmInlineAsm(P<LlvmInlineAsm>),
    MacCall(MacCall),
    Struct(P<StructExpr>),
    Repeat(P<Expr>, AnonConst),
    Paren(P<Expr>),
    Try(P<Expr>),
    Yield(Option<P<Expr>>),
    Err,
}

Variants

Box(P<Expr>)

A box x expression.

Array(Vec<P<Expr>>)

An array ([a, b, c, d])

ConstBlock(AnonConst)

Allow anonymous constants from an inline const block

Call(P<Expr>, Vec<P<Expr>>)

A function call

The first field resolves to the function itself, and the second field is the list of arguments. This also represents calling the constructor of tuple-like ADTs such as tuple structs and enum variants.

MethodCall(PathSegment, Vec<P<Expr>>, Span)

A method call (x.foo::<'static, Bar, Baz>(a, b, c, d))

The PathSegment represents the method name and its generic arguments (within the angle brackets). The first element of the vector of an Expr is the expression that evaluates to the object on which the method is being called on (the receiver), and the remaining elements are the rest of the arguments. Thus, x.foo::<Bar, Baz>(a, b, c, d) is represented as ExprKind::MethodCall(PathSegment { foo, [Bar, Baz] }, [x, a, b, c, d]). This Span is the span of the function, without the dot and receiver (e.g. foo(a, b) in x.foo(a, b)

Tup(Vec<P<Expr>>)

A tuple (e.g., (a, b, c, d)).

Binary(BinOp, P<Expr>, P<Expr>)

A binary operation (e.g., a + b, a * b).

Unary(UnOp, P<Expr>)

A unary operation (e.g., !x, *x).

Lit(Lit)

A literal (e.g., 1, "foo").

Cast(P<Expr>, P<Ty>)

A cast (e.g., foo as f64).

Type(P<Expr>, P<Ty>)

A type ascription (e.g., 42: usize).

Let(P<Pat>, P<Expr>)

A let pat = expr expression that is only semantically allowed in the condition of if / while expressions. (e.g., if let 0 = x { .. }).

If(P<Expr>, P<Block>, Option<P<Expr>>)

An if block, with an optional else block.

if expr { block } else { expr }

While(P<Expr>, P<Block>, Option<Label>)

A while loop, with an optional label.

'label: while expr { block }

ForLoop(P<Pat>, P<Expr>, P<Block>, Option<Label>)

A for loop, with an optional label.

'label: for pat in expr { block }

This is desugared to a combination of loop and match expressions.

Loop(P<Block>, Option<Label>)

Conditionless loop (can be exited with break, continue, or return).

'label: loop { block }

Match(P<Expr>, Vec<Arm>)

A match block.

Closure(CaptureBy, Async, Movability, P<FnDecl>, P<Expr>, Span)

A closure (e.g., move |a, b, c| a + b + c).

The final span is the span of the argument block |...|.

Block(P<Block>, Option<Label>)

A block ('label: { ... }).

Async(CaptureBy, NodeId, P<Block>)

An async block (async move { ... }).

The NodeId is the NodeId for the closure that results from desugaring an async block, just like the NodeId field in the Async::Yes variant. This is necessary in order to create a def for the closure which can be used as a parent of any child defs. Defs created during lowering cannot be made the parent of any other preexisting defs.

Await(P<Expr>)

An await expression (my_future.await).

TryBlock(P<Block>)

A try block (try { ... }).

Assign(P<Expr>, P<Expr>, Span)

An assignment (a = foo()). The Span argument is the span of the = token.

AssignOp(BinOp, P<Expr>, P<Expr>)

An assignment with an operator.

E.g., a += 1.

Field(P<Expr>, Ident)

Access of a named (e.g., obj.foo) or unnamed (e.g., obj.0) struct field.

Index(P<Expr>, P<Expr>)

An indexing operation (e.g., foo[2]).

Range(Option<P<Expr>>, Option<P<Expr>>, RangeLimits)

A range (e.g., 1..2, 1.., ..2, 1..=2, ..=2; and .. in destructuring assignment).

Underscore

An underscore, used in destructuring assignment to ignore a value.

Path(Option<QSelf>, Path)

Variable reference, possibly containing :: and/or type parameters (e.g., foo::bar::<baz>).

Optionally “qualified” (e.g., <Vec<T> as SomeTrait>::SomeType).

AddrOf(BorrowKind, Mutability, P<Expr>)

A referencing operation (&a, &mut a, &raw const a or &raw mut a).

Break(Option<Label>, Option<P<Expr>>)

A break, with an optional label to break, and an optional expression.

Continue(Option<Label>)

A continue, with an optional label.

Ret(Option<P<Expr>>)

A return, with an optional value to be returned.

InlineAsm(P<InlineAsm>)

Output of the asm!() macro.

LlvmInlineAsm(P<LlvmInlineAsm>)

Output of the llvm_asm!() macro.

MacCall(MacCall)

A macro invocation; pre-expansion.

Struct(P<StructExpr>)

A struct literal expression.

E.g., Foo {x: 1, y: 2}, or Foo {x: 1, .. rest}.

Repeat(P<Expr>, AnonConst)

An array literal constructed from one repeated element.

E.g., [1; 5]. The expression is the element to be repeated; the constant is the number of times to repeat it.

Paren(P<Expr>)

No-op: used solely so we can pretty-print faithfully.

Try(P<Expr>)

A try expression (expr?).

Yield(Option<P<Expr>>)

A yield, with an optional value to be yielded.

Err

Placeholder for an expression that wasn’t syntactically well formed in some way.

Trait Implementations

impl Clone for ExprKind

fn clone(&self) -> ExprKind

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ExprKind

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<__D: Decoder> Decodable<__D> for ExprKind

fn decode(__decoder: &mut __D) -> Result<Self, <__D as Decoder>::Error>

impl<__E: Encoder> Encodable<__E> for ExprKind

fn encode(&self, __encoder: &mut __E) -> Result<(), <__E as Encoder>::Error>