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//! Declaration nodes
use crate::{
builtins::{iterable::get_iterator, Array},
environment::lexical_environment::VariableScope,
exec::Executable,
gc::{Finalize, Trace},
syntax::ast::node::{join_nodes, Identifier, Node},
Context, JsResult, JsValue,
};
use std::fmt;
#[cfg(feature = "deser")]
use serde::{Deserialize, Serialize};
pub mod arrow_function_decl;
pub mod async_function_decl;
pub mod async_function_expr;
pub mod function_decl;
pub mod function_expr;
pub use self::{
arrow_function_decl::ArrowFunctionDecl, async_function_decl::AsyncFunctionDecl,
async_function_expr::AsyncFunctionExpr, function_decl::FunctionDecl,
function_expr::FunctionExpr,
};
#[cfg(test)]
mod tests;
#[cfg_attr(feature = "deser", derive(Serialize, Deserialize))]
#[derive(Clone, Debug, Trace, Finalize, PartialEq)]
pub enum DeclarationList {
/// The `const` statements are block-scoped, much like variables defined using the `let`
/// keyword.
///
/// This declaration creates a constant whose scope can be either global or local to the block
/// in which it is declared. Global constants do not become properties of the window object,
/// unlike var variables.
///
/// An initializer for a constant is required. You must specify its value in the same statement
/// in which it's declared. (This makes sense, given that it can't be changed later.)
///
/// More information:
/// - [ECMAScript reference][spec]
/// - [MDN documentation][mdn]
///
/// [spec]: https://tc39.es/ecma262/#sec-let-and-const-declarations
/// [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/const
/// [identifier]: https://developer.mozilla.org/en-US/docs/Glossary/identifier
/// [expression]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Expressions_and_Operators#Expressions
Const(Box<[Declaration]>),
/// The `let` statement declares a block scope local variable, optionally initializing it to a
/// value.
///
///
/// `let` allows you to declare variables that are limited to a scope of a block statement, or
/// expression on which it is used, unlike the `var` keyword, which defines a variable
/// globally, or locally to an entire function regardless of block scope.
///
/// Just like const the `let` does not create properties of the window object when declared
/// globally (in the top-most scope).
///
/// More information:
/// - [ECMAScript reference][spec]
/// - [MDN documentation][mdn]
///
/// [spec]: https://tc39.es/ecma262/#sec-let-and-const-declarations
/// [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/let
Let(Box<[Declaration]>),
/// The `var` statement declares a variable, optionally initializing it to a value.
///
/// var declarations, wherever they occur, are processed before any code is executed. This is
/// called hoisting, and is discussed further below.
///
/// The scope of a variable declared with var is its current execution context, which is either
/// the enclosing function or, for variables declared outside any function, global. If you
/// re-declare a JavaScript variable, it will not lose its value.
///
/// Assigning a value to an undeclared variable implicitly creates it as a global variable (it
/// becomes a property of the global object) when the assignment is executed.
///
/// More information:
/// - [ECMAScript reference][spec]
/// - [MDN documentation][mdn]
///
/// [spec]: https://tc39.es/ecma262/#prod-VariableStatement
/// [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/var
Var(Box<[Declaration]>),
}
impl Executable for DeclarationList {
fn run(&self, context: &mut Context) -> JsResult<JsValue> {
for decl in self.as_ref() {
use DeclarationList::*;
let val = match decl.init() {
None if self.is_const() => {
return context.throw_syntax_error("missing = in const declaration")
}
Some(init) => init.run(context)?,
None => JsValue::undefined(),
};
match &decl {
Declaration::Identifier { ident, init } => {
if self.is_var() && context.has_binding(ident.as_ref())? {
if init.is_some() {
context.set_mutable_binding(ident.as_ref(), val, context.strict())?;
}
continue;
}
match &self {
Const(_) => context.create_immutable_binding(
ident.as_ref(),
false,
VariableScope::Block,
)?,
Let(_) => context.create_mutable_binding(
ident.as_ref(),
false,
VariableScope::Block,
)?,
Var(_) => context.create_mutable_binding(
ident.as_ref(),
false,
VariableScope::Function,
)?,
}
context.initialize_binding(ident.as_ref(), val)?;
}
Declaration::Pattern(p) => {
for (ident, value) in p.run(None, context)? {
if self.is_var() && context.has_binding(ident.as_ref())? {
if !value.is_undefined() {
context.set_mutable_binding(
ident.as_ref(),
value,
context.strict(),
)?;
}
continue;
}
match &self {
Const(_) => context.create_immutable_binding(
ident.as_ref(),
false,
VariableScope::Block,
)?,
Let(_) => context.create_mutable_binding(
ident.as_ref(),
false,
VariableScope::Block,
)?,
Var(_) => context.create_mutable_binding(
ident.as_ref(),
false,
VariableScope::Function,
)?,
}
context.initialize_binding(ident.as_ref(), value)?;
}
}
}
}
Ok(JsValue::undefined())
}
}
impl DeclarationList {
#[allow(dead_code)]
pub(in crate::syntax) fn is_let(&self) -> bool {
matches!(self, Self::Let(_))
}
pub(in crate::syntax) fn is_const(&self) -> bool {
matches!(self, Self::Const(_))
}
pub(in crate::syntax) fn is_var(&self) -> bool {
matches!(self, Self::Var(_))
}
}
impl AsRef<[Declaration]> for DeclarationList {
fn as_ref(&self) -> &[Declaration] {
use DeclarationList::*;
match self {
Var(list) | Const(list) | Let(list) => list,
}
}
}
impl fmt::Display for DeclarationList {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if !self.as_ref().is_empty() {
use DeclarationList::*;
match &self {
Let(_) => write!(f, "let ")?,
Const(_) => write!(f, "const ")?,
Var(_) => write!(f, "var ")?,
}
join_nodes(f, self.as_ref())
} else {
Ok(())
}
}
}
impl From<DeclarationList> for Node {
fn from(list: DeclarationList) -> Self {
use DeclarationList::*;
match &list {
Let(_) => Node::LetDeclList(list),
Const(_) => Node::ConstDeclList(list),
Var(_) => Node::VarDeclList(list),
}
}
}
impl From<Declaration> for Box<[Declaration]> {
fn from(d: Declaration) -> Self {
Box::new([d])
}
}
/// Declaration represents either an individual binding or a binding pattern.
///
/// For `let` and `const` declarations this type represents a [LexicalBinding][spec1]
///
/// For `var` declarations this type represents a [VariableDeclaration][spec2]
///
/// More information:
/// - [ECMAScript reference: 14.3 Declarations and the Variable Statement][spec3]
///
/// [spec1]: https://tc39.es/ecma262/#prod-LexicalBinding
/// [spec2]: https://tc39.es/ecma262/#prod-VariableDeclaration
/// [spec3]: https://tc39.es/ecma262/#sec-declarations-and-the-variable-statement
#[cfg_attr(feature = "deser", derive(Serialize, Deserialize))]
#[derive(Clone, Debug, Trace, Finalize, PartialEq)]
pub enum Declaration {
Identifier {
ident: Identifier,
init: Option<Node>,
},
Pattern(DeclarationPattern),
}
impl fmt::Display for Declaration {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match &self {
Self::Identifier { ident, init } => {
fmt::Display::fmt(&ident, f)?;
if let Some(ref init) = &init {
write!(f, " = {}", init)?;
}
}
Self::Pattern(pattern) => {
fmt::Display::fmt(&pattern, f)?;
}
}
Ok(())
}
}
impl Declaration {
/// Creates a new variable declaration with a BindingIdentifier.
#[inline]
pub(in crate::syntax) fn new_with_identifier<N, I>(ident: N, init: I) -> Self
where
N: Into<Identifier>,
I: Into<Option<Node>>,
{
Self::Identifier {
ident: ident.into(),
init: init.into(),
}
}
/// Creates a new variable declaration with an ObjectBindingPattern.
#[inline]
pub(in crate::syntax) fn new_with_object_pattern<I>(
bindings: Vec<BindingPatternTypeObject>,
init: I,
) -> Self
where
I: Into<Option<Node>>,
{
Self::Pattern(DeclarationPattern::Object(DeclarationPatternObject::new(
bindings,
init.into(),
)))
}
/// Creates a new variable declaration with an ArrayBindingPattern.
#[inline]
pub(in crate::syntax) fn new_with_array_pattern<I>(
bindings: Vec<BindingPatternTypeArray>,
init: I,
) -> Self
where
I: Into<Option<Node>>,
{
Self::Pattern(DeclarationPattern::Array(DeclarationPatternArray::new(
bindings,
init.into(),
)))
}
/// Gets the initialization node for the declaration, if any.
#[inline]
pub(crate) fn init(&self) -> Option<&Node> {
match &self {
Self::Identifier { init, .. } => init.as_ref(),
Self::Pattern(pattern) => pattern.init(),
}
}
}
/// DeclarationPattern represents an object or array binding pattern.
///
/// This enum mostly wraps the functionality of the specific binding pattern types.
///
/// More information:
/// - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - BindingPattern][spec1]
///
/// [spec1]: https://tc39.es/ecma262/#prod-BindingPattern
#[cfg_attr(feature = "deser", derive(Serialize, Deserialize))]
#[derive(Clone, Debug, Trace, Finalize, PartialEq)]
pub enum DeclarationPattern {
Object(DeclarationPatternObject),
Array(DeclarationPatternArray),
}
impl fmt::Display for DeclarationPattern {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match &self {
DeclarationPattern::Object(o) => {
fmt::Display::fmt(o, f)?;
}
DeclarationPattern::Array(a) => {
fmt::Display::fmt(a, f)?;
}
}
Ok(())
}
}
impl DeclarationPattern {
/// Initialize the values of an object/array binding pattern.
///
/// This function only calls the specific initialization function for either the object or the array binding pattern.
/// For specific documentation and references to the ECMAScript spec, look at the called initialization functions.
#[inline]
pub(in crate::syntax) fn run(
&self,
init: Option<JsValue>,
context: &mut Context,
) -> JsResult<Vec<(Box<str>, JsValue)>> {
match &self {
DeclarationPattern::Object(pattern) => pattern.run(init, context),
DeclarationPattern::Array(pattern) => pattern.run(init, context),
}
}
/// Gets the list of identifiers declared by the binding pattern.
///
/// A single binding pattern may declare 0 to n identifiers.
#[inline]
pub fn idents(&self) -> Vec<&str> {
match &self {
DeclarationPattern::Object(pattern) => pattern.idents(),
DeclarationPattern::Array(pattern) => pattern.idents(),
}
}
/// Gets the initialization node for the binding pattern, if any.
#[inline]
pub fn init(&self) -> Option<&Node> {
match &self {
DeclarationPattern::Object(pattern) => pattern.init(),
DeclarationPattern::Array(pattern) => pattern.init(),
}
}
}
/// DeclarationPatternObject represents an object binding pattern.
///
/// This struct holds a list of bindings, and an optional initializer for the binding pattern.
///
/// More information:
/// - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - ObjectBindingPattern][spec1]
///
/// [spec1]: https://tc39.es/ecma262/#prod-ObjectBindingPattern
#[cfg_attr(feature = "deser", derive(Serialize, Deserialize))]
#[derive(Clone, Debug, Trace, Finalize, PartialEq)]
pub struct DeclarationPatternObject {
bindings: Vec<BindingPatternTypeObject>,
init: Option<Node>,
}
impl fmt::Display for DeclarationPatternObject {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Display::fmt("{", f)?;
for (i, binding) in self.bindings.iter().enumerate() {
if i == self.bindings.len() - 1 {
write!(f, "{} ", binding)?;
} else {
write!(f, "{},", binding)?;
}
}
fmt::Display::fmt("}", f)?;
if let Some(ref init) = self.init {
write!(f, " = {}", init)?;
}
Ok(())
}
}
impl DeclarationPatternObject {
/// Create a new object binding pattern.
#[inline]
pub(in crate::syntax) fn new(
bindings: Vec<BindingPatternTypeObject>,
init: Option<Node>,
) -> Self {
Self { bindings, init }
}
/// Gets the initialization node for the object binding pattern, if any.
#[inline]
pub(in crate::syntax) fn init(&self) -> Option<&Node> {
self.init.as_ref()
}
/// Initialize the values of an object binding pattern.
///
/// More information:
/// - [ECMAScript reference: 8.5.2 Runtime Semantics: BindingInitialization][spec1]
/// - [ECMAScript reference:14.3.3.3 Runtime Semantics: KeyedBindingInitialization][spec2]
/// - [ECMAScript reference:14.3.3.2 Runtime Semantics: RestBindingInitialization][spec3]
///
/// [spec1]: https://tc39.es/ecma262/#sec-runtime-semantics-bindinginitialization
/// [spec2]: https://tc39.es/ecma262/#sec-runtime-semantics-keyedbindinginitialization
/// [spec3]: https://tc39.es/ecma262/#sec-destructuring-binding-patterns-runtime-semantics-restbindinginitialization
pub(in crate::syntax) fn run(
&self,
init: Option<JsValue>,
context: &mut Context,
) -> JsResult<Vec<(Box<str>, JsValue)>> {
let value = if let Some(value) = init {
value
} else if let Some(node) = &self.init {
node.run(context)?
} else {
JsValue::undefined()
};
if value.is_null() {
return Err(context.construct_type_error("Cannot destructure 'null' value"));
}
if value.is_undefined() {
return Err(context.construct_type_error("Cannot destructure 'undefined' value"));
}
// 1. Perform ? RequireObjectCoercible(value).
let value = value.require_object_coercible(context)?;
let mut results = Vec::new();
// 2. Return the result of performing BindingInitialization for ObjectBindingPattern using value and environment as arguments.
for binding in &self.bindings {
use BindingPatternTypeObject::*;
match binding {
// ObjectBindingPattern : { }
Empty => {
// 1. Return NormalCompletion(empty).
}
// SingleNameBinding : BindingIdentifier Initializer[opt]
SingleName {
ident,
property_name,
default_init,
} => {
// 1. Let bindingId be StringValue of BindingIdentifier.
// 2. Let lhs be ? ResolveBinding(bindingId, environment).
// 3. Let v be ? GetV(value, propertyName).
let mut v = value.get_field(property_name.as_ref(), context)?;
// 4. If Initializer is present and v is undefined, then
if let Some(init) = default_init {
if v.is_undefined() {
// TODO: a. not implemented yet:
// a. If IsAnonymousFunctionDefinition(Initializer) is true, then
// i. Set v to the result of performing NamedEvaluation for Initializer with argument bindingId.
// b. Else,
// i. Let defaultValue be the result of evaluating Initializer.
// ii. Set v to ? GetValue(defaultValue).
v = init.run(context)?;
}
}
// 5. If environment is undefined, return ? PutValue(lhs, v).
// 6. Return InitializeReferencedBinding(lhs, v).
results.push((ident.clone(), v));
}
// BindingRestProperty : ... BindingIdentifier
RestProperty {
ident,
excluded_keys,
} => {
// 1. Let lhs be ? ResolveBinding(StringValue of BindingIdentifier, environment).
// 2. Let restObj be ! OrdinaryObjectCreate(%Object.prototype%).
let mut rest_obj = context.construct_object();
// 3. Perform ? CopyDataProperties(restObj, value, excludedNames).
rest_obj.copy_data_properties(value, excluded_keys.clone(), context)?;
// 4. If environment is undefined, return PutValue(lhs, restObj).
// 5. Return InitializeReferencedBinding(lhs, restObj).
results.push((ident.clone(), rest_obj.into()));
}
// BindingElement : BindingPattern Initializer[opt]
BindingPattern {
ident,
pattern,
default_init,
} => {
// 1. Let v be ? GetV(value, propertyName).
let mut v = value.get_field(ident.as_ref(), context)?;
// 2. If Initializer is present and v is undefined, then
if let Some(init) = default_init {
if v.is_undefined() {
// a. Let defaultValue be the result of evaluating Initializer.
// b. Set v to ? GetValue(defaultValue).
v = init.run(context)?;
}
}
// 3. Return the result of performing BindingInitialization for BindingPattern passing v and environment as arguments.
results.append(&mut pattern.run(Some(v), context)?);
}
}
}
Ok(results)
}
/// Gets the list of identifiers declared by the object binding pattern.
#[inline]
pub(in crate::syntax) fn idents(&self) -> Vec<&str> {
let mut idents = Vec::new();
for binding in &self.bindings {
use BindingPatternTypeObject::*;
match binding {
Empty => {}
SingleName {
ident,
property_name: _,
default_init: _,
} => {
idents.push(ident.as_ref());
}
RestProperty {
ident: property_name,
excluded_keys: _,
} => {
idents.push(property_name.as_ref());
}
BindingPattern {
ident: _,
pattern,
default_init: _,
} => {
for ident in pattern.idents() {
idents.push(ident);
}
}
}
}
idents
}
}
/// DeclarationPatternArray represents an array binding pattern.
///
/// This struct holds a list of bindings, and an optional initializer for the binding pattern.
///
/// More information:
/// - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - ArrayBindingPattern][spec1]
///
/// [spec1]: https://tc39.es/ecma262/#prod-ArrayBindingPattern
#[cfg_attr(feature = "deser", derive(Serialize, Deserialize))]
#[derive(Clone, Debug, Trace, Finalize, PartialEq)]
pub struct DeclarationPatternArray {
bindings: Vec<BindingPatternTypeArray>,
init: Option<Node>,
}
impl fmt::Display for DeclarationPatternArray {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Display::fmt("[", f)?;
for (i, binding) in self.bindings.iter().enumerate() {
if i == self.bindings.len() - 1 {
match binding {
BindingPatternTypeArray::Elision => write!(f, "{}, ", binding)?,
_ => write!(f, "{} ", binding)?,
}
} else {
write!(f, "{},", binding)?;
}
}
fmt::Display::fmt("]", f)?;
if let Some(ref init) = self.init {
write!(f, " = {}", init)?;
}
Ok(())
}
}
impl DeclarationPatternArray {
/// Create a new array binding pattern.
#[inline]
pub(in crate::syntax) fn new(
bindings: Vec<BindingPatternTypeArray>,
init: Option<Node>,
) -> Self {
Self { bindings, init }
}
/// Gets the initialization node for the array binding pattern, if any.
#[inline]
pub(in crate::syntax) fn init(&self) -> Option<&Node> {
self.init.as_ref()
}
/// Initialize the values of an array binding pattern.
///
/// More information:
/// - [ECMAScript reference: 8.5.2 Runtime Semantics: BindingInitialization][spec1]
/// - [ECMAScript reference: 8.5.3 Runtime Semantics: IteratorBindingInitialization][spec2]
///
/// [spec1]: https://tc39.es/ecma262/#sec-runtime-semantics-bindinginitialization
/// [spec2]: https://tc39.es/ecma262/#sec-runtime-semantics-iteratorbindinginitialization
pub(in crate::syntax) fn run(
&self,
init: Option<JsValue>,
context: &mut Context,
) -> JsResult<Vec<(Box<str>, JsValue)>> {
let value = if let Some(value) = init {
value
} else if let Some(node) = &self.init {
node.run(context)?
} else {
JsValue::undefined()
};
if value.is_null() {
return Err(context.construct_type_error("Cannot destructure 'null' value"));
}
if value.is_undefined() {
return Err(context.construct_type_error("Cannot destructure 'undefined' value"));
}
// 1. Let iteratorRecord be ? GetIterator(value).
let iterator = get_iterator(&value, context)?;
let mut result = Vec::new();
// 2. Let result be IteratorBindingInitialization of ArrayBindingPattern with arguments iteratorRecord and environment.
for binding in &self.bindings {
use BindingPatternTypeArray::*;
match binding {
// ArrayBindingPattern : [ ]
Empty => {
// 1. Return NormalCompletion(empty).
}
// ArrayBindingPattern : [ Elision ]
// Note: This captures all elisions due to our representation of a the binding pattern.
Elision => {
// 1. If iteratorRecord.[[Done]] is false, then
// a. Let next be IteratorStep(iteratorRecord).
// b. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
// c. ReturnIfAbrupt(next).
// d. If next is false, set iteratorRecord.[[Done]] to true.
let _ = iterator.next(context)?;
// 2. Return NormalCompletion(empty).
}
// SingleNameBinding : BindingIdentifier Initializer[opt]
SingleName {
ident,
default_init,
} => {
// 1. Let bindingId be StringValue of BindingIdentifier.
// 2. Let lhs be ? ResolveBinding(bindingId, environment).
let next = iterator.next(context)?;
// 3. If iteratorRecord.[[Done]] is false, then
// 4. If iteratorRecord.[[Done]] is true, let v be undefined.
let mut v = if !next.done {
// a. Let next be IteratorStep(iteratorRecord).
// b. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
// c. ReturnIfAbrupt(next).
// d. If next is false, set iteratorRecord.[[Done]] to true.
// e. Else,
// i. Let v be IteratorValue(next).
// ii. If v is an abrupt completion, set iteratorRecord.[[Done]] to true.
// iii. ReturnIfAbrupt(v).
next.value
} else {
JsValue::undefined()
};
// 5. If Initializer is present and v is undefined, then
if let Some(init) = default_init {
if v.is_undefined() {
// TODO: a. not implemented yet:
// a. If IsAnonymousFunctionDefinition(Initializer) is true, then
// i. Set v to the result of performing NamedEvaluation for Initializer with argument bindingId.
// b. Else,
// i. Let defaultValue be the result of evaluating Initializer.
// ii. Set v to ? GetValue(defaultValue).
v = init.run(context)?
}
}
// 6. If environment is undefined, return ? PutValue(lhs, v).
// 7. Return InitializeReferencedBinding(lhs, v).
result.push((ident.clone(), v));
}
// BindingElement : BindingPattern Initializer[opt]
BindingPattern { pattern } => {
let next = iterator.next(context)?;
// 1. If iteratorRecord.[[Done]] is false, then
// 2. If iteratorRecord.[[Done]] is true, let v be undefined.
let v = if !next.done {
// a. Let next be IteratorStep(iteratorRecord).
// b. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
// c. ReturnIfAbrupt(next).
// d. If next is false, set iteratorRecord.[[Done]] to true.
// e. Else,
// i. Let v be IteratorValue(next).
// ii. If v is an abrupt completion, set iteratorRecord.[[Done]] to true.
// iii. ReturnIfAbrupt(v).
Some(next.value)
} else {
None
};
// 3. If Initializer is present and v is undefined, then
// a. Let defaultValue be the result of evaluating Initializer.
// b. Set v to ? GetValue(defaultValue).
// 4. Return the result of performing BindingInitialization of BindingPattern with v and environment as the arguments.
result.append(&mut pattern.run(v, context)?);
}
// BindingRestElement : ... BindingIdentifier
SingleNameRest { ident } => {
// 1. Let lhs be ? ResolveBinding(StringValue of BindingIdentifier, environment).
// 2. Let A be ! ArrayCreate(0).
// 3. Let n be 0.
let a = Array::array_create(0, None, context)
.expect("Array creation with 0 length should never fail");
// 4. Repeat,
loop {
let next = iterator.next(context)?;
// a. If iteratorRecord.[[Done]] is false, then
// i. Let next be IteratorStep(iteratorRecord).
// ii. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
// iii. ReturnIfAbrupt(next).
// iv. If next is false, set iteratorRecord.[[Done]] to true.
// b. If iteratorRecord.[[Done]] is true, then
if next.done {
// i. If environment is undefined, return ? PutValue(lhs, A).
// ii. Return InitializeReferencedBinding(lhs, A).
break result.push((ident.clone(), a.clone().into()));
}
// c. Let nextValue be IteratorValue(next).
// d. If nextValue is an abrupt completion, set iteratorRecord.[[Done]] to true.
// e. ReturnIfAbrupt(nextValue).
// f. Perform ! CreateDataPropertyOrThrow(A, ! ToString(𝔽(n)), nextValue).
// g. Set n to n + 1.
Array::add_to_array_object(&a.clone().into(), &[next.value], context)?;
}
}
// BindingRestElement : ... BindingPattern
BindingPatternRest { pattern } => {
// 1. Let A be ! ArrayCreate(0).
// 2. Let n be 0.
let a = Array::array_create(0, None, context)
.expect("Array creation with 0 length should never fail");
// 3. Repeat,
loop {
// a. If iteratorRecord.[[Done]] is false, then
// i. Let next be IteratorStep(iteratorRecord).
// ii. If next is an abrupt completion, set iteratorRecord.[[Done]] to true.
// iii. ReturnIfAbrupt(next).
// iv. If next is false, set iteratorRecord.[[Done]] to true.
let next = iterator.next(context)?;
// b. If iteratorRecord.[[Done]] is true, then
if next.done {
// i. Return the result of performing BindingInitialization of BindingPattern with A and environment as the arguments.
break result
.append(&mut pattern.run(Some(a.clone().into()), context)?);
}
// c. Let nextValue be IteratorValue(next).
// d. If nextValue is an abrupt completion, set iteratorRecord.[[Done]] to true.
// e. ReturnIfAbrupt(nextValue).
// f. Perform ! CreateDataPropertyOrThrow(A, ! ToString(𝔽(n)), nextValue).
// g. Set n to n + 1.
Array::add_to_array_object(&a.clone().into(), &[next.value], context)?;
}
}
}
}
// 3. If iteratorRecord.[[Done]] is false, return ? IteratorClose(iteratorRecord, result).
// 4. Return result.
Ok(result)
}
/// Gets the list of identifiers declared by the array binding pattern.
#[inline]
pub(in crate::syntax) fn idents(&self) -> Vec<&str> {
let mut idents = Vec::new();
for binding in &self.bindings {
use BindingPatternTypeArray::*;
match binding {
Empty => {}
Elision => {}
SingleName {
ident,
default_init: _,
} => {
idents.push(ident.as_ref());
}
BindingPattern { pattern } | BindingPatternRest { pattern } => {
let mut i = pattern.idents();
idents.append(&mut i)
}
SingleNameRest { ident } => idents.push(ident),
}
}
idents
}
}
/// BindingPatternTypeObject represents the different types of bindings that an object binding pattern may contain.
///
/// More information:
/// - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - ObjectBindingPattern][spec1]
///
/// [spec1]: https://tc39.es/ecma262/#prod-ObjectBindingPattern
#[cfg_attr(feature = "deser", derive(Serialize, Deserialize))]
#[derive(Clone, Debug, Trace, Finalize, PartialEq)]
pub enum BindingPatternTypeObject {
/// Empty represents an empty object binding pattern e.g. `{ }`.
Empty,
/// SingleName represents one of the following properties:
///
/// - `SingleNameBinding` with an identifier and an optional default initializer.
/// - `BindingProperty` with an property name and a `SingleNameBinding` as the `BindingElement`.
///
/// More information:
/// - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - SingleNameBinding][spec1]
/// - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - BindingProperty][spec2]
///
/// [spec1]: https://tc39.es/ecma262/#prod-SingleNameBinding
/// [spec2]: https://tc39.es/ecma262/#prod-BindingProperty
SingleName {
ident: Box<str>,
property_name: Box<str>,
default_init: Option<Node>,
},
/// RestProperty represents a `BindingRestProperty` with an identifier.
///
/// It also includes a list of the property keys that should be excluded from the rest,
/// because they where already assigned.
///
/// More information:
/// - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - BindingRestProperty][spec1]
///
/// [spec1]: https://tc39.es/ecma262/#prod-BindingRestProperty
RestProperty {
ident: Box<str>,
excluded_keys: Vec<Box<str>>,
},
/// BindingPattern represents a `BindingProperty` with a `BindingPattern` as the `BindingElement`.
///
/// Additionally to the identifier of the new property and the nested binding pattern,
/// this may also include an optional default initializer.
///
/// More information:
/// - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - BindingProperty][spec1]
///
/// [spec1]: https://tc39.es/ecma262/#prod-BindingProperty
BindingPattern {
ident: Box<str>,
pattern: DeclarationPattern,
default_init: Option<Node>,
},
}
impl fmt::Display for BindingPatternTypeObject {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match &self {
BindingPatternTypeObject::Empty => {}
BindingPatternTypeObject::SingleName {
ident,
property_name,
default_init,
} => {
if ident == property_name {
write!(f, " {}", ident)?;
} else {
write!(f, " {} : {}", property_name, ident)?;
}
if let Some(ref init) = default_init {
write!(f, " = {}", init)?;
}
}
BindingPatternTypeObject::RestProperty {
ident: property_name,
excluded_keys: _,
} => {
write!(f, " ... {}", property_name)?;
}
BindingPatternTypeObject::BindingPattern {
ident: property_name,
pattern,
default_init,
} => {
write!(f, " {} : {}", property_name, pattern)?;
if let Some(ref init) = default_init {
write!(f, " = {}", init)?;
}
}
}
Ok(())
}
}
/// BindingPatternTypeArray represents the different types of bindings that an array binding pattern may contain.
///
/// More information:
/// - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - ArrayBindingPattern][spec1]
///
/// [spec1]: https://tc39.es/ecma262/#prod-ArrayBindingPattern
#[cfg_attr(feature = "deser", derive(Serialize, Deserialize))]
#[derive(Clone, Debug, Trace, Finalize, PartialEq)]
pub enum BindingPatternTypeArray {
/// Empty represents an empty array binding pattern e.g. `[ ]`.
///
/// This may occur because the `Elision` and `BindingRestElement` in the first type of
/// array binding pattern are both optional.
///
/// More information:
/// - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - ArrayBindingPattern][spec1]
///
/// [spec1]: https://tc39.es/ecma262/#prod-ArrayBindingPattern
Empty,
/// Elision represents the elision of an item in the array binding pattern.
///
/// An `Elision` may occur at multiple points in the pattern and may be multiple elisions.
/// This variant strictly represents one elision. If there are multiple, this should be used multiple times.
///
/// More information:
/// - [ECMAScript reference: 13.2.4 Array Initializer - Elision][spec1]
///
/// [spec1]: https://tc39.es/ecma262/#prod-Elision
Elision,
/// SingleName represents a `SingleNameBinding` with an identifier and an optional default initializer.
///
/// More information:
/// - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - SingleNameBinding][spec1]
///
/// [spec1]: https://tc39.es/ecma262/#prod-SingleNameBinding
SingleName {
ident: Box<str>,
default_init: Option<Node>,
},
/// BindingPattern represents a `BindingPattern` in a `BindingElement` of an array binding pattern.
///
/// The pattern and the optional default initializer are both stored in the DeclarationPattern.
///
/// More information:
/// - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - BindingElement][spec1]
///
/// [spec1]: https://tc39.es/ecma262/#prod-BindingElement
BindingPattern { pattern: DeclarationPattern },
/// SingleNameRest represents a `BindingIdentifier` in a `BindingRestElement` of an array binding pattern.
///
/// More information:
/// - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - BindingRestElement][spec1]
///
/// [spec1]: https://tc39.es/ecma262/#prod-BindingRestElement
SingleNameRest { ident: Box<str> },
/// SingleNameRest represents a `BindingPattern` in a `BindingRestElement` of an array binding pattern.
///
/// More information:
/// - [ECMAScript reference: 14.3.3 Destructuring Binding Patterns - BindingRestElement][spec1]
///
/// [spec1]: https://tc39.es/ecma262/#prod-BindingRestElement
BindingPatternRest { pattern: DeclarationPattern },
}
impl fmt::Display for BindingPatternTypeArray {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match &self {
BindingPatternTypeArray::Empty => {}
BindingPatternTypeArray::Elision => {
fmt::Display::fmt(" ", f)?;
}
BindingPatternTypeArray::SingleName {
ident,
default_init,
} => {
write!(f, " {}", ident)?;
if let Some(ref init) = default_init {
write!(f, " = {}", init)?;
}
}
BindingPatternTypeArray::BindingPattern { pattern } => {
write!(f, " {}", pattern)?;
}
BindingPatternTypeArray::SingleNameRest { ident } => {
write!(f, " ... {}", ident)?;
}
BindingPatternTypeArray::BindingPatternRest { pattern } => {
write!(f, " ... {}", pattern)?;
}
}
Ok(())
}
}