oxc/crates/oxc_syntax/src/reference.rs

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#![allow(missing_docs)] // fixme
use bitflags::bitflags;
use nonmax::NonMaxU32;
use oxc_allocator::CloneIn;
use oxc_index::Idx;
#[cfg(feature = "serialize")]
use serde::{Serialize, Serializer};
use crate::{node::NodeId, symbol::SymbolId};
#[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub struct ReferenceId(NonMaxU32);
impl Idx for ReferenceId {
#[allow(clippy::cast_possible_truncation)]
fn from_usize(idx: usize) -> Self {
assert!(idx < u32::MAX as usize);
// SAFETY: We just checked `idx` is a legal value for `NonMaxU32`
Self(unsafe { NonMaxU32::new_unchecked(idx as u32) })
}
fn index(self) -> usize {
self.0.get() as usize
}
}
#[cfg(feature = "serialize")]
impl Serialize for ReferenceId {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
serializer.serialize_u32(self.0.get())
}
}
#[cfg(feature = "serialize")]
#[wasm_bindgen::prelude::wasm_bindgen(typescript_custom_section)]
const TS_APPEND_CONTENT: &'static str = r#"
export type ReferenceId = number;
export type ReferenceFlags = {
None: 0,
Read: 0b1,
Write: 0b10,
Type: 0b100,
Value: 0b11
}
"#;
bitflags! {
/// 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:
///
/// ```js
/// 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.
///
/// [`Read`]: ReferenceFlags::Read
/// [`Write`]: ReferenceFlags::Write
/// [`Type`]: ReferenceFlags::Type
/// [`ValueAsType`]: ReferenceFlags::ValueAsType
#[derive(Debug, Default, Clone, Copy, Eq, PartialEq)]
#[cfg_attr(feature = "serialize", derive(Serialize))]
pub struct ReferenceFlags: u8 {
const None = 0;
/// 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`](https://tc39.es/ecma262/#sec-getvalue)
/// is called on a expression, and the expression is an `IdentifierReference`.
///
/// For example:
/// ```text
/// 1. Let lRef be ? Evaluation of Expression.
/// 2. Perform ? GetValue(lRef).
/// ```
const Read = 1 << 0;
/// 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`](https://tc39.es/ecma262/#sec-putvalue)
/// is called on a expression, and the expression is an `IdentifierReference`.
///
/// For example:
/// ```text
/// 1. Let lhs be ? Evaluation of LeftHandSideExpression.
/// 2. Perform ? PutValue(lhs, newValue).
/// ```
const Write = 1 << 1;
/// Used in type definitions.
const Type = 1 << 2;
/// A value symbol is used in a type context, such as in `typeof` expressions.
const ValueAsType = 1 << 3;
/// 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`].
///
/// [`Read`]: ReferenceFlags::Read
const Value = Self::Read.bits() | Self::Write.bits();
}
}
impl ReferenceFlags {
#[inline]
pub const fn read() -> Self {
Self::Read
}
#[inline]
pub const fn write() -> Self {
Self::Write
}
#[inline]
pub const fn read_write() -> Self {
Self::Value
}
/// The identifier is read from. It may also be written to.
#[inline]
pub const fn is_read(&self) -> bool {
self.intersects(Self::Read)
}
/// The identifier is only read from.
#[inline]
pub const fn is_read_only(&self) -> bool {
self.contains(Self::Read)
}
/// The identifier is written to. It may also be read from.
#[inline]
pub const fn is_write(&self) -> bool {
self.intersects(Self::Write)
}
/// The identifier is only written to. It is not read from in this reference.
#[inline]
pub const fn is_write_only(&self) -> bool {
self.contains(Self::Write)
}
/// The identifier is both read from and written to, e.g `a += 1`.
#[inline]
pub fn is_read_write(&self) -> bool {
self.contains(Self::Read | Self::Write)
}
/// Checks if the reference is a value being used in a type context.
#[inline]
pub fn is_value_as_type(&self) -> bool {
self.contains(Self::ValueAsType)
}
/// The identifier is used in a type definition.
#[inline]
pub const fn is_type(&self) -> bool {
self.contains(Self::Type)
}
#[inline]
pub const fn is_type_only(self) -> bool {
matches!(self, Self::Type)
}
#[inline]
pub const fn is_value(&self) -> bool {
self.intersects(Self::Value)
}
}
impl<'alloc> CloneIn<'alloc> for ReferenceFlags {
type Cloned = Self;
fn clone_in(&self, _: &'alloc oxc_allocator::Allocator) -> Self::Cloned {
*self
}
}
/// Describes where and how a Symbol is used in the AST.
///
/// References indicate how they are being used using [`ReferenceFlags`]. Refer
/// to the documentation for [`ReferenceFlags`] for more information.
///
/// ## Resolution
/// References to symbols that could be resolved have their `symbol_id` field
/// populated. [`None`] indicates that either a global variable or a
/// non-existent symbol is being referenced.
///
/// The node identified by `node_id` will be an `IdentifierReference`.
/// Note that declarations do not count as references, even if the declaration
/// is being used in an expression.
///
/// ```ts
/// const arr = [1, 2, 3].map(function mapper(x) { return x + 1; });
/// // Not considered a reference ^^^^^^
/// ```
#[cfg_attr(feature = "serialize", derive(Serialize), serde(rename_all = "camelCase"))]
#[derive(Debug, Clone)]
pub struct Reference {
/// The AST node making the reference.
node_id: NodeId,
/// The symbol being referenced.
///
/// This will be [`None`] if no symbol could be found within
/// the reference's scope tree. Usually this indicates a global variable or
/// a reference to a non-existent symbol.
symbol_id: Option<SymbolId>,
/// Describes how this referenced is used by other AST nodes. References can
/// be reads, writes, or both.
flags: ReferenceFlags,
}
impl Reference {
/// Create a new unresolved reference.
#[inline]
pub fn new(node_id: NodeId, flags: ReferenceFlags) -> Self {
Self { node_id, symbol_id: None, flags }
}
/// Create a new resolved reference on a symbol.
#[inline]
pub fn new_with_symbol_id(node_id: NodeId, symbol_id: SymbolId, flags: ReferenceFlags) -> Self {
Self { node_id, symbol_id: Some(symbol_id), flags }
}
/// Get the id of the node that is referencing the symbol.
#[inline]
pub fn node_id(&self) -> NodeId {
self.node_id
}
/// Get the id of the symbol being referenced.
///
/// Will return [`None`] if the symbol could not be resolved.
#[inline]
pub fn symbol_id(&self) -> Option<SymbolId> {
self.symbol_id
}
#[inline]
pub fn set_symbol_id(&mut self, symbol_id: SymbolId) {
self.symbol_id = Some(symbol_id);
}
#[inline]
pub fn flags(&self) -> ReferenceFlags {
self.flags
}
#[inline]
pub fn flags_mut(&mut self) -> &mut ReferenceFlags {
&mut self.flags
}
/// Returns `true` if the identifier value was read.
///
/// This is not mutually exclusive with [`Reference::is_write`].
#[inline]
pub fn is_read(&self) -> bool {
self.flags.is_read()
}
/// Returns `true` if the identifier was written to.
///
/// This is not mutually exclusive with [`Reference::is_read`].
#[inline]
pub fn is_write(&self) -> bool {
self.flags.is_write()
}
/// Returns `true` if this reference is used in a value context.
pub fn is_value(&self) -> bool {
self.flags.is_value()
}
/// Returns `true` if this reference is used in a type context.
#[inline]
pub fn is_type(&self) -> bool {
self.flags.is_type()
}
}