Struct ReferenceFlags

pub struct ReferenceFlags(/* private fields */);

Describes how a symbol is being referenced in the AST.

There are three general categories of references:

1. Values being referenced as values
2. Types being referenced as types
3. Values being used in type contexts

Values

Whether a reference is considered Read or Write is determined according to ECMA spec.

See comments on Read and Write below.

Counter-intuitively, y in x = y = z is Write only. x = y = z is equivalent to:

var _temp = z;
y = _temp;
x = _temp;

See https://github.com/oxc-project/oxc/issues/5165#issuecomment-2488333549 for a runtime test to determine Read/Write operations in a code snippet.

Value as Type

The ValueAsType flag is a temporary marker for references that need to resolve to value symbols initially, but will ultimately be treated as type references. This flag is crucial in scenarios like TypeScript’s typeof operator.

For example, in type T = typeof a:

1. The reference to ‘a’ is initially flagged with ValueAsType.
2. This ensures that during symbol resolution, ‘a’ should be a value symbol.
3. However, the final resolved reference’s flags will be treated as a type.

Types

Type references are indicated by Type. These are used primarily in type definitions and signatures. Types can never be re-assigned, so there is no read/write distinction for type references.

Implementations

impl ReferenceFlags

pub const None: Self

pub const Read: Self

Symbol is being read from as a Value.

Whether a reference is Read is as defined in the spec:

Under Runtime Semantics: Evaluation, when GetValue is called on a expression, and the expression is an IdentifierReference.

For example:

1. Let lRef be ? Evaluation of Expression.
2. Perform ? GetValue(lRef).

pub const Write: Self

Symbol is being written to as a Value.

Whether a reference is Write is as defined in the spec:

Under Runtime Semantics: Evaluation, when PutValue is called on a expression, and the expression is an IdentifierReference.

For example:

1. Let lhs be ? Evaluation of LeftHandSideExpression.
2. Perform ? PutValue(lhs, newValue).

pub const Type: Self

Used in type definitions.

pub const ValueAsType: Self

A value symbol is used in a type context, such as in typeof expressions.

pub const Value: Self

The symbol being referenced is a value.

Note that this does not necessarily indicate the reference is used in a value context, since type queries are also flagged as Read.

impl ReferenceFlags

pub const fn empty() -> Self

Get a flags value with all bits unset.

pub const fn all() -> Self

Get a flags value with all known bits set.

pub const fn bits(&self) -> u8

Get the underlying bits value.

The returned value is exactly the bits set in this flags value.

pub const fn from_bits(bits: u8) -> Option<Self>

Convert from a bits value.

This method will return None if any unknown bits are set.

pub const fn from_bits_truncate(bits: u8) -> Self

Convert from a bits value, unsetting any unknown bits.

pub const fn from_bits_retain(bits: u8) -> Self

Convert from a bits value exactly.

pub fn from_name(name: &str) -> Option<Self>

Get a flags value with the bits of a flag with the given name set.

This method will return None if name is empty or doesn’t correspond to any named flag.

pub const fn is_empty(&self) -> bool

Whether all bits in this flags value are unset.

pub const fn is_all(&self) -> bool

Whether all known bits in this flags value are set.

pub const fn intersects(&self, other: Self) -> bool

Whether any set bits in a source flags value are also set in a target flags value.

pub const fn contains(&self, other: Self) -> bool

Whether all set bits in a source flags value are also set in a target flags value.

pub fn insert(&mut self, other: Self)

The bitwise or (|) of the bits in two flags values.

pub fn remove(&mut self, other: Self)

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. remove won’t truncate other, but the ! operator will.

pub fn toggle(&mut self, other: Self)

The bitwise exclusive-or (^) of the bits in two flags values.

pub fn set(&mut self, other: Self, value: bool)

Call insert when value is true or remove when value is false.

pub const fn intersection(self, other: Self) -> Self

The bitwise and (&) of the bits in two flags values.

pub const fn union(self, other: Self) -> Self

The bitwise or (|) of the bits in two flags values.

pub const fn difference(self, other: Self) -> Self

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. difference won’t truncate other, but the ! operator will.

pub const fn symmetric_difference(self, other: Self) -> Self

The bitwise exclusive-or (^) of the bits in two flags values.

pub const fn complement(self) -> Self

The bitwise negation (!) of the bits in a flags value, truncating the result.

impl ReferenceFlags

pub const fn iter(&self) -> Iter<ReferenceFlags>

Yield a set of contained flags values.

Each yielded flags value will correspond to a defined named flag. Any unknown bits will be yielded together as a final flags value.

pub const fn iter_names(&self) -> IterNames<ReferenceFlags>

Yield a set of contained named flags values.

This method is like iter, except only yields bits in contained named flags. Any unknown bits, or bits not corresponding to a contained flag will not be yielded.

impl ReferenceFlags

pub const fn read() -> Self

pub const fn write() -> Self

pub const fn read_write() -> Self

pub const fn is_read(&self) -> bool

The identifier is read from. It may also be written to.

pub const fn is_read_only(&self) -> bool

The identifier is only read from.

pub const fn is_write(&self) -> bool

The identifier is written to. It may also be read from.

pub const fn is_write_only(&self) -> bool

The identifier is only written to. It is not read from in this reference.

pub fn is_read_write(&self) -> bool

The identifier is both read from and written to, e.g a += 1.

pub fn is_value_as_type(&self) -> bool

Checks if the reference is a value being used in a type context.

pub const fn is_type(&self) -> bool

The identifier is used in a type definition.

pub const fn is_type_only(self) -> bool

pub const fn is_value(&self) -> bool

Trait Implementations

impl Binary for ReferenceFlags

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

Formats the value using the given formatter.

impl BitAnd for ReferenceFlags

fn bitand(self, other: Self) -> Self

The bitwise and (&) of the bits in two flags values.

type Output = ReferenceFlags

The resulting type after applying the & operator.

impl BitAndAssign for ReferenceFlags

fn bitand_assign(&mut self, other: Self)

The bitwise and (&) of the bits in two flags values.

impl BitOr for ReferenceFlags

fn bitor(self, other: ReferenceFlags) -> Self

The bitwise or (|) of the bits in two flags values.

type Output = ReferenceFlags

The resulting type after applying the | operator.

impl BitOrAssign for ReferenceFlags

fn bitor_assign(&mut self, other: Self)

The bitwise or (|) of the bits in two flags values.

impl BitXor for ReferenceFlags

fn bitxor(self, other: Self) -> Self

The bitwise exclusive-or (^) of the bits in two flags values.

type Output = ReferenceFlags

The resulting type after applying the ^ operator.

impl BitXorAssign for ReferenceFlags

fn bitxor_assign(&mut self, other: Self)

The bitwise exclusive-or (^) of the bits in two flags values.

impl Clone for ReferenceFlags

fn clone(&self) -> ReferenceFlags

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'alloc> CloneIn<'alloc> for ReferenceFlags

type Cloned = ReferenceFlags

The type of the cloned object.

fn clone_in(&self, _: &'alloc Allocator) -> Self::Cloned

Clone self into the given allocator. allocator may be the same one that self is already in.

fn clone_in_with_semantic_ids( &self, allocator: &'new_alloc Allocator, ) -> Self::Cloned

Almost identical as clone_in, but for some special type, it will also clone the semantic ids. Please use this method only if you make sure semantic info is synced with the ast node.

impl Debug for ReferenceFlags

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

Formats the value using the given formatter.

impl Default for ReferenceFlags

fn default() -> ReferenceFlags

Returns the “default value” for a type.

impl Extend<ReferenceFlags> for ReferenceFlags

fn extend<T: IntoIterator<Item = Self>>(&mut self, iterator: T)

The bitwise or (|) of the bits in each flags value.

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl Flags for ReferenceFlags

const FLAGS: &'static [Flag<ReferenceFlags>]

The set of defined flags.

type Bits = u8

The underlying bits type.

fn bits(&self) -> u8

Get the underlying bits value.

fn from_bits_retain(bits: u8) -> ReferenceFlags

Convert from a bits value exactly.

fn empty() -> Self

Get a flags value with all bits unset.

fn all() -> Self

Get a flags value with all known bits set.

fn contains_unknown_bits(&self) -> bool

This method will return true if any unknown bits are set.

fn from_bits(bits: Self::Bits) -> Option<Self>

Convert from a bits value.

fn from_bits_truncate(bits: Self::Bits) -> Self

Convert from a bits value, unsetting any unknown bits.

fn from_name(name: &str) -> Option<Self>

Get a flags value with the bits of a flag with the given name set.

fn iter(&self) -> Iter<Self>

Yield a set of contained flags values.

fn iter_names(&self) -> IterNames<Self>

Yield a set of contained named flags values.

fn is_empty(&self) -> bool

Whether all bits in this flags value are unset.

fn is_all(&self) -> bool

Whether all known bits in this flags value are set.

fn intersects(&self, other: Self) -> bool

where Self: Sized,

Whether any set bits in a source flags value are also set in a target flags value.

fn contains(&self, other: Self) -> bool

where Self: Sized,

Whether all set bits in a source flags value are also set in a target flags value.

fn truncate(&mut self)

where Self: Sized,

Remove any unknown bits from the flags.

fn insert(&mut self, other: Self)

where Self: Sized,

The bitwise or (|) of the bits in two flags values.

fn remove(&mut self, other: Self)

where Self: Sized,

The intersection of a source flags value with the complement of a target flags value (&!).

fn toggle(&mut self, other: Self)

where Self: Sized,

The bitwise exclusive-or (^) of the bits in two flags values.

fn set(&mut self, other: Self, value: bool)

where Self: Sized,

Call Flags::insert when value is true or Flags::remove when value is false.

fn clear(&mut self)

where Self: Sized,

Unsets all bits in the flags.

fn intersection(self, other: Self) -> Self

The bitwise and (&) of the bits in two flags values.

fn union(self, other: Self) -> Self

The bitwise or (|) of the bits in two flags values.

fn difference(self, other: Self) -> Self

The intersection of a source flags value with the complement of a target flags value (&!).

fn symmetric_difference(self, other: Self) -> Self

The bitwise exclusive-or (^) of the bits in two flags values.

fn complement(self) -> Self

The bitwise negation (!) of the bits in a flags value, truncating the result.

impl FromIterator<ReferenceFlags> for ReferenceFlags

fn from_iter<T: IntoIterator<Item = Self>>(iterator: T) -> Self

The bitwise or (|) of the bits in each flags value.

impl IntoIterator for ReferenceFlags

type Item = ReferenceFlags

The type of the elements being iterated over.

type IntoIter = Iter<ReferenceFlags>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl LowerHex for ReferenceFlags

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

Formats the value using the given formatter.

impl Not for ReferenceFlags

fn not(self) -> Self

The bitwise negation (!) of the bits in a flags value, truncating the result.

type Output = ReferenceFlags

The resulting type after applying the ! operator.

impl Octal for ReferenceFlags

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

Formats the value using the given formatter.

impl PartialEq for ReferenceFlags

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

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PublicFlags for ReferenceFlags

type Primitive = u8

The type of the underlying storage.

type Internal = InternalBitFlags

The type of the internal field on the generated flags type.

impl Sub for ReferenceFlags

fn sub(self, other: Self) -> Self

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. difference won’t truncate other, but the ! operator will.

type Output = ReferenceFlags

The resulting type after applying the - operator.

impl SubAssign for ReferenceFlags

fn sub_assign(&mut self, other: Self)

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. difference won’t truncate other, but the ! operator will.

impl UpperHex for ReferenceFlags

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

Formats the value using the given formatter.

impl Copy for ReferenceFlags

impl Eq for ReferenceFlags

impl StructuralPartialEq for ReferenceFlags