Enum boa::syntax::ast::op::UnaryOp

pub enum UnaryOp {
    IncrementPost,
    IncrementPre,
    DecrementPost,
    DecrementPre,
    Minus,
    Plus,
    Not,
    Tilde,
    TypeOf,
    Delete,
    Void,
}

A unary operator is one that takes a single operand/argument and performs an operation.

A unary operation is an operation with only one operand. This operand comes either before or after the operator. Unary operators are more efficient than standard JavaScript function calls.

More information:

• ECMAScript reference
• MDN documentation

Variants

IncrementPost

The increment operator increments (adds one to) its operand and returns a value.

Syntax: ++x

This operator increments and returns the value after incrementing.

More information:

• ECMAScript reference
• MDN documentation

IncrementPre

The increment operator increments (adds one to) its operand and returns a value.

Syntax: x++

This operator increments and returns the value before incrementing.

More information:

• ECMAScript reference
• MDN documentation

DecrementPost

The decrement operator decrements (subtracts one from) its operand and returns a value.

Syntax: --x

This operator decrements and returns the value before decrementing.

More information:

• ECMAScript reference
• MDN documentation

DecrementPre

The decrement operator decrements (subtracts one from) its operand and returns a value.

Syntax: x--

This operator decrements the operand and returns the value after decrementing.

More information:

• ECMAScript reference
• MDN documentation

Minus

The unary negation operator precedes its operand and negates it.

Syntax: -x

Converts non-numbers data types to numbers like unary plus, however, it performs an additional operation, negation.

More information:

• ECMAScript reference
• MDN documentation

Plus

The unary plus operator attempts to convert the operand into a number, if it isn't already.

Syntax: +x

Although unary negation (-) also can convert non-numbers, unary plus is the fastest and preferred way of converting something into a number, because it does not perform any other operations on the number. It can convert string representations of integers and floats, as well as the non-string values true, false, and null.

More information:

• ECMAScript reference
• MDN documentation

Not

Returns false if its single operand can be converted to true; otherwise, returns true.

Syntax: !x

Boolean values simply get inverted: !true === false and !false === true. Non-boolean values get converted to boolean values first, then are negated. This means that it is possible to use a couple of NOT operators in series to explicitly force the conversion of any value to the corresponding boolean primitive.

More information:

• ECMAScript reference
• MDN documentation

Tilde

Performs the NOT operator on each bit.

Syntax: ~x

NOT a yields the inverted value (or one's complement) of a. Bitwise NOTing any number x yields -(x + 1). For example, ~-5 yields 4.

More information:

• ECMAScript reference
• MDN documentation

TypeOf

The typeof operator returns a string indicating the type of the unevaluated operand.

Syntax: typeof x or typeof(x)

The typeof is a JavaScript keyword that will return the type of a variable when you call it. You can use this to validate function parameters or check if variables are defined. There are other uses as well.

More information:

• ECMAScript reference
• MDN documentation

Delete

The JavaScript delete operator removes a property from an object.

Syntax: delete x

Unlike what common belief suggests, the delete operator has nothing to do with directly freeing memory. Memory management is done indirectly via breaking references. If no more references to the same property are held, it is eventually released automatically.

The delete operator returns true for all cases except when the property is an own non-configurable property, in which case, false is returned in non-strict mode.

More information:

• ECMAScript reference
• MDN documentation

Void

The void operator evaluates the given expression and then returns undefined.

Syntax: void x

This operator allows evaluating expressions that produce a value into places where an expression that evaluates to undefined is desired. The void operator is often used merely to obtain the undefined primitive value, usually using void(0) (which is equivalent to void 0). In these cases, the global variable undefined can be used.

When using an immediately-invoked function expression, void can be used to force the function keyword to be treated as an expression instead of a declaration.

More information:

• ECMAScript reference
• MDN documentation

Trait Implementations

impl Clone for UnaryOp

fn clone(&self) -> UnaryOp

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Copy for UnaryOp

impl Debug for UnaryOp

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

Formats the value using the given formatter.

impl Display for UnaryOp

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

Formats the value using the given formatter.

impl Finalize for UnaryOp

fn finalize(&self)

impl PartialEq<UnaryOp> for UnaryOp

fn eq(&self, other: &UnaryOp) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl StructuralPartialEq for UnaryOp

impl Trace for UnaryOp

unsafe fn trace(&self)

Marks all contained Gcs.

unsafe fn root(&self)

Increments the root-count of all contained Gcs.

unsafe fn unroot(&self)

Decrements the root-count of all contained Gcs.

fn finalize_glue(&self)

Runs Finalize::finalize() on this object and all contained subobjects