Enum rustc_hir::ExprKind

pub enum ExprKind<'hir> {
    Box(&'hir Expr<'hir>),
    ConstBlock(AnonConst),
    Array(&'hir [Expr<'hir>]),
    Call(&'hir Expr<'hir>, &'hir [Expr<'hir>]),
    MethodCall(&'hir PathSegment<'hir>, Span, &'hir [Expr<'hir>], Span),
    Tup(&'hir [Expr<'hir>]),
    Binary(BinOp, &'hir Expr<'hir>, &'hir Expr<'hir>),
    Unary(UnOp, &'hir Expr<'hir>),
    Lit(Lit),
    Cast(&'hir Expr<'hir>, &'hir Ty<'hir>),
    Type(&'hir Expr<'hir>, &'hir Ty<'hir>),
    DropTemps(&'hir Expr<'hir>),
    If(&'hir Expr<'hir>, &'hir Expr<'hir>, Option<&'hir Expr<'hir>>),
    Loop(&'hir Block<'hir>, Option<Label>, LoopSource, Span),
    Match(&'hir Expr<'hir>, &'hir [Arm<'hir>], MatchSource),
    Closure(CaptureBy, &'hir FnDecl<'hir>, BodyId, Span, Option<Movability>),
    Block(&'hir Block<'hir>, Option<Label>),
    Assign(&'hir Expr<'hir>, &'hir Expr<'hir>, Span),
    AssignOp(BinOp, &'hir Expr<'hir>, &'hir Expr<'hir>),
    Field(&'hir Expr<'hir>, Ident),
    Index(&'hir Expr<'hir>, &'hir Expr<'hir>),
    Path(QPath<'hir>),
    AddrOf(BorrowKind, Mutability, &'hir Expr<'hir>),
    Break(Destination, Option<&'hir Expr<'hir>>),
    Continue(Destination),
    Ret(Option<&'hir Expr<'hir>>),
    InlineAsm(&'hir InlineAsm<'hir>),
    LlvmInlineAsm(&'hir LlvmInlineAsm<'hir>),
    Struct(&'hir QPath<'hir>, &'hir [ExprField<'hir>], Option<&'hir Expr<'hir>>),
    Repeat(&'hir Expr<'hir>, AnonConst),
    Yield(&'hir Expr<'hir>, YieldSource),
    Err,
}

Variants

Box(&'hir Expr<'hir>)

A box x expression.

ConstBlock(AnonConst)

Allow anonymous constants from an inline const block

Array(&'hir [Expr<'hir>])

An array (e.g., [a, b, c, d]).

Call(&'hir Expr<'hir>, &'hir [Expr<'hir>])

A function call.

The first field resolves to the function itself (usually an ExprKind::Path), 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(&'hir PathSegment<'hir>, Span, &'hir [Expr<'hir>], Span)

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

The PathSegment/Span represent the method name and its generic arguments (within the angle brackets). The first element of the vector of Exprs 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]). The final Span represents the span of the function and arguments (e.g. foo::<Bar, Baz>(a, b, c, d) in x.foo::<Bar, Baz>(a, b, c, d)

To resolve the called method to a DefId, call type_dependent_def_id with the hir_id of the MethodCall node itself.

Tup(&'hir [Expr<'hir>])

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

Binary(BinOp, &'hir Expr<'hir>, &'hir Expr<'hir>)

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

Unary(UnOp, &'hir Expr<'hir>)

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

Lit(Lit)

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

Cast(&'hir Expr<'hir>, &'hir Ty<'hir>)

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

Type(&'hir Expr<'hir>, &'hir Ty<'hir>)

A type reference (e.g., Foo).

DropTemps(&'hir Expr<'hir>)

Wraps the expression in a terminating scope. This makes it semantically equivalent to { let _t = expr; _t }.

This construct only exists to tweak the drop order in HIR lowering. An example of that is the desugaring of for loops.

If(&'hir Expr<'hir>, &'hir Expr<'hir>, Option<&'hir Expr<'hir>>)

An if block, with an optional else block.

I.e., if <expr> { <expr> } else { <expr> }.

Loop(&'hir Block<'hir>, Option<Label>, LoopSource, Span)

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

I.e., 'label: loop { <block> }.

The Span is the loop header (for x in y/while let pat = expr).

Match(&'hir Expr<'hir>, &'hir [Arm<'hir>], MatchSource)

A match block, with a source that indicates whether or not it is the result of a desugaring, and if so, which kind.

Closure(CaptureBy, &'hir FnDecl<'hir>, BodyId, Span, Option<Movability>)

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

The Span is the argument block |...|.

This may also be a generator literal or an async block as indicated by the Option<Movability>.

Block(&'hir Block<'hir>, Option<Label>)

A block (e.g., 'label: { ... }).

Assign(&'hir Expr<'hir>, &'hir Expr<'hir>, Span)

An assignment (e.g., a = foo()).

AssignOp(BinOp, &'hir Expr<'hir>, &'hir Expr<'hir>)

An assignment with an operator.

E.g., a += 1.

Field(&'hir Expr<'hir>, Ident)

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

Index(&'hir Expr<'hir>, &'hir Expr<'hir>)

An indexing operation (foo[2]).

Path(QPath<'hir>)

Path to a definition, possibly containing lifetime or type parameters.

AddrOf(BorrowKind, Mutability, &'hir Expr<'hir>)

A referencing operation (i.e., &a or &mut a).

Break(Destination, Option<&'hir Expr<'hir>>)

A break, with an optional label to break.

Continue(Destination)

A continue, with an optional label.

Ret(Option<&'hir Expr<'hir>>)

A return, with an optional value to be returned.

InlineAsm(&'hir InlineAsm<'hir>)

Inline assembly (from asm!), with its outputs and inputs.

LlvmInlineAsm(&'hir LlvmInlineAsm<'hir>)

Inline assembly (from llvm_asm!), with its outputs and inputs.

Struct(&'hir QPath<'hir>, &'hir [ExprField<'hir>], Option<&'hir Expr<'hir>>)

A struct or struct-like variant literal expression.

E.g., Foo {x: 1, y: 2}, or Foo {x: 1, .. base}, where base is the Option<Expr>.

Repeat(&'hir Expr<'hir>, AnonConst)

An array literal constructed from one repeated element.

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

Yield(&'hir Expr<'hir>, YieldSource)

A suspension point for generators (i.e., yield <expr>).

Err

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

Trait Implementations

impl<'hir> Debug for ExprKind<'hir>

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

Formats the value using the given formatter.

impl<'hir, __CTX> HashStable<__CTX> for ExprKind<'hir> where
    __CTX: HashStableContext, 

fn hash_stable(&self, __hcx: &mut __CTX, __hasher: &mut StableHasher)