oxc_ast/ast_impl/

js.rs

#![warn(missing_docs)]
use std::{
    borrow::Cow,
    fmt::{self, Display},
};

use oxc_span::{Atom, GetSpan, Span};
use oxc_syntax::{operator::UnaryOperator, scope::ScopeFlags};

use crate::ast::*;

impl Program<'_> {
    /// Returns `true` if this program has no statements or directives.
    pub fn is_empty(&self) -> bool {
        self.body.is_empty() && self.directives.is_empty()
    }

    /// Returns `true` if this program has a `"use strict"` directive.
    pub fn has_use_strict_directive(&self) -> bool {
        self.directives.iter().any(Directive::is_use_strict)
    }
}

impl<'a> Expression<'a> {
    /// Returns `true` if this expression is TypeScript-specific syntax.
    pub fn is_typescript_syntax(&self) -> bool {
        matches!(
            self,
            Self::TSAsExpression(_)
                | Self::TSSatisfiesExpression(_)
                | Self::TSTypeAssertion(_)
                | Self::TSNonNullExpression(_)
                | Self::TSInstantiationExpression(_)
        )
    }

    /// Returns `true` if this is a [primary expression](https://tc39.es/ecma262/#sec-primary-expression).
    pub fn is_primary_expression(&self) -> bool {
        self.is_literal()
            || matches!(
                self,
                Self::Identifier(_)
                    | Self::ThisExpression(_)
                    | Self::FunctionExpression(_)
                    | Self::ClassExpression(_)
                    | Self::ParenthesizedExpression(_)
                    | Self::ArrayExpression(_)
                    | Self::ObjectExpression(_)
            )
    }

    /// `true` if this [`Expression`] is a literal expression for a primitive value.
    ///
    /// Does not include [`TemplateLiteral`]s, [`object literals`], or [`array literals`].
    ///
    /// [`object literals`]: ObjectExpression
    /// [`array literals`]: ArrayExpression
    pub fn is_literal(&self) -> bool {
        // Note: TemplateLiteral is not `Literal`
        matches!(
            self,
            Self::BooleanLiteral(_)
                | Self::NullLiteral(_)
                | Self::NumericLiteral(_)
                | Self::BigIntLiteral(_)
                | Self::RegExpLiteral(_)
                | Self::StringLiteral(_)
        )
    }

    /// Returns `true` for [string](StringLiteral) and [template](TemplateLiteral) literals.
    pub fn is_string_literal(&self) -> bool {
        matches!(self, Self::StringLiteral(_) | Self::TemplateLiteral(_))
    }

    /// Return `true` if the expression is a plain template.
    pub fn is_no_substitution_template(&self) -> bool {
        matches!(self, Expression::TemplateLiteral(e) if e.is_no_substitution_template())
    }

    /// Returns `true` for [numeric](NumericLiteral) and [big int](BigIntLiteral) literals.
    pub fn is_number_literal(&self) -> bool {
        matches!(self, Self::NumericLiteral(_) | Self::BigIntLiteral(_))
    }

    /// Returns `true` for [bigint literals](BigIntLiteral).
    pub fn is_big_int_literal(&self) -> bool {
        matches!(self, Self::BigIntLiteral(_))
    }

    /// Returns `true` for [string literals](StringLiteral) matching the
    /// expected value. Note that [non-substitution template
    /// literals](TemplateLiteral) are not considered.
    #[inline]
    pub fn is_specific_string_literal(&self, string: &str) -> bool {
        match self {
            Self::StringLiteral(s) => s.value == string,
            _ => false,
        }
    }

    /// Determines whether the given expr is a `null` literal
    pub fn is_null(&self) -> bool {
        matches!(self, Expression::NullLiteral(_))
    }

    /// Determines whether the given expr is a `undefined` literal
    pub fn is_undefined(&self) -> bool {
        matches!(self, Self::Identifier(ident) if ident.name == "undefined")
    }

    /// Determines whether the given expr is a `void expr`
    pub fn is_void(&self) -> bool {
        matches!(self, Self::UnaryExpression(expr) if expr.operator == UnaryOperator::Void)
    }

    /// Determines whether the given expr is a `void 0`
    pub fn is_void_0(&self) -> bool {
        match self {
            Self::UnaryExpression(expr) if expr.operator == UnaryOperator::Void => {
                matches!(&expr.argument, Self::NumericLiteral(lit) if lit.value == 0.0)
            }
            _ => false,
        }
    }

    /// Returns `true` for [numeric literals](NumericLiteral)
    pub fn is_number(&self) -> bool {
        matches!(self, Self::NumericLiteral(_))
    }

    /// Determines whether the given expr is a `0`
    pub fn is_number_0(&self) -> bool {
        matches!(self, Self::NumericLiteral(lit) if lit.value == 0.0)
    }

    /// Determines whether the given expr is a specific [number](NumericLiteral) literal.
    pub fn is_number_value(&self, val: f64) -> bool {
        matches!(self, Self::NumericLiteral(lit) if (lit.value - val).abs() < f64::EPSILON)
    }

    /// Determines whether the given numeral literal's raw value is exactly val
    pub fn is_specific_raw_number_literal(&self, val: &str) -> bool {
        matches!(self, Self::NumericLiteral(lit) if lit.raw.as_ref().is_some_and(|raw| raw == val))
    }

    /// Determines whether the given expr evaluate to `undefined`
    pub fn evaluate_to_undefined(&self) -> bool {
        self.is_undefined() || self.is_void()
    }

    /// Determines whether the given expr is a `null` or `undefined` or `void 0`
    ///
    /// Corresponds to a [nullish value check](https://developer.mozilla.org/en-US/docs/Glossary/Nullish).
    pub fn is_null_or_undefined(&self) -> bool {
        self.is_null() || self.evaluate_to_undefined()
    }

    /// Determines whether the given expr is a `NaN` literal
    pub fn is_nan(&self) -> bool {
        matches!(self, Self::Identifier(ident) if ident.name == "NaN")
    }

    /// Remove nested parentheses from this expression.
    pub fn without_parentheses(&self) -> &Self {
        let mut expr = self;
        while let Expression::ParenthesizedExpression(paren_expr) = expr {
            expr = &paren_expr.expression;
        }
        expr
    }

    /// Remove nested parentheses from this expression.
    pub fn without_parentheses_mut(&mut self) -> &mut Self {
        let mut expr = self;
        while let Expression::ParenthesizedExpression(paran_expr) = expr {
            expr = &mut paran_expr.expression;
        }
        expr
    }

    /// Returns `true` if this [`Expression`] is an [`IdentifierReference`] with specified `name`.
    pub fn is_specific_id(&self, name: &str) -> bool {
        match self.get_inner_expression() {
            Expression::Identifier(ident) => ident.name == name,
            _ => false,
        }
    }

    /// Returns `true` if this [`Expression`] is a [`MemberExpression`] with the specified `object`
    /// name and `property` name.
    ///
    /// For example, `Array.from` is a specific member access with `object` `Array` and `property` `from`
    /// and could be checked like `expr.is_specific_member_access("Array", "from")`.
    pub fn is_specific_member_access(&self, object: &str, property: &str) -> bool {
        match self.get_inner_expression() {
            expr if expr.is_member_expression() => {
                expr.to_member_expression().is_specific_member_access(object, property)
            }
            Expression::ChainExpression(chain) => {
                let Some(expr) = chain.expression.as_member_expression() else {
                    return false;
                };
                expr.is_specific_member_access(object, property)
            }
            _ => false,
        }
    }

    /// Returns the expression inside of this one, if applicable, and takes ownership of it.
    /// For example, if the expression is a [`ParenthesizedExpression`], it will return the
    /// expression inside the parentheses. Or if this is part of a TypeScript expression
    /// like `as`, `satisfies`, or `!`, then it will return the expression that is being type asserted.
    ///
    /// For getting a reference to the expression inside, use [`Expression::get_inner_expression`].
    #[must_use]
    pub fn into_inner_expression(self) -> Expression<'a> {
        let mut expr = self;
        loop {
            expr = match expr {
                Expression::ParenthesizedExpression(e) => e.unbox().expression,
                Expression::TSAsExpression(e) => e.unbox().expression,
                Expression::TSSatisfiesExpression(e) => e.unbox().expression,
                Expression::TSInstantiationExpression(e) => e.unbox().expression,
                Expression::TSNonNullExpression(e) => e.unbox().expression,
                Expression::TSTypeAssertion(e) => e.unbox().expression,
                _ => break,
            };
        }
        expr
    }

    /// Gets the expression inside of this one, if applicable, and returns a reference to it.
    /// For example, if the expression is a [`ParenthesizedExpression`], it will return the
    /// expression inside the parentheses. Or if this is part of a TypeScript expression
    /// like `as`, `satisfies`, or `!`, then it will return the expression that is being type asserted.
    ///
    /// For taking ownership of the expression inside, use [`Expression::into_inner_expression`].
    /// For getting a mutable reference to the expression inside, use [`Expression::get_inner_expression_mut`].
    pub fn get_inner_expression(&self) -> &Expression<'a> {
        let mut expr = self;
        loop {
            expr = match expr {
                Expression::ParenthesizedExpression(e) => &e.expression,
                Expression::TSAsExpression(e) => &e.expression,
                Expression::TSSatisfiesExpression(e) => &e.expression,
                Expression::TSInstantiationExpression(e) => &e.expression,
                Expression::TSNonNullExpression(e) => &e.expression,
                Expression::TSTypeAssertion(e) => &e.expression,
                _ => break,
            };
        }
        expr
    }

    /// Gets the expression inside of this one, if applicable, and returns a mutable reference to it.
    /// For example, if the expression is a [`ParenthesizedExpression`], it will return the
    /// expression inside the parentheses. Or if this is part of a TypeScript expression
    /// like `as`, `satisfies`, or `!`, then it will return the expression that is being type asserted.
    ///
    /// For taking ownership of the expression inside, use [`Expression::into_inner_expression`].
    /// For getting an immutable reference to the expression inside, use [`Expression::get_inner_expression`].
    pub fn get_inner_expression_mut(&mut self) -> &mut Expression<'a> {
        let mut expr = self;
        loop {
            expr = match expr {
                Expression::ParenthesizedExpression(e) => &mut e.expression,
                Expression::TSAsExpression(e) => &mut e.expression,
                Expression::TSSatisfiesExpression(e) => &mut e.expression,
                Expression::TSInstantiationExpression(e) => &mut e.expression,
                Expression::TSNonNullExpression(e) => &mut e.expression,
                Expression::TSTypeAssertion(e) => &mut e.expression,
                _ => break,
            };
        }
        expr
    }

    /// Turns any chainable expression such as `a.b` or `b()` into the chained equivalent
    /// such as `a?.b` or `b?.()`.
    pub fn into_chain_element(self) -> Option<ChainElement<'a>> {
        match self {
            Expression::StaticMemberExpression(e) => Some(ChainElement::StaticMemberExpression(e)),
            Expression::ComputedMemberExpression(e) => {
                Some(ChainElement::ComputedMemberExpression(e))
            }
            Expression::PrivateFieldExpression(e) => Some(ChainElement::PrivateFieldExpression(e)),
            Expression::CallExpression(e) => Some(ChainElement::CallExpression(e)),
            Expression::TSNonNullExpression(e) => Some(ChainElement::TSNonNullExpression(e)),
            _ => None,
        }
    }

    /// Returns `true` if this [`Expression`] is an [`IdentifierReference`].
    pub fn is_identifier_reference(&self) -> bool {
        matches!(self, Expression::Identifier(_))
    }

    /// Returns the [`IdentifierReference`] if this expression is an [`Expression::Identifier`],
    /// or contains an [`Expression::Identifier`] and reruns `None` otherwise.
    pub fn get_identifier_reference(&self) -> Option<&IdentifierReference<'a>> {
        match self.get_inner_expression() {
            Expression::Identifier(ident) => Some(ident),
            _ => None,
        }
    }

    /// Returns `true` if this [`Expression`] is a function
    /// (either [`Function`] or [`ArrowFunctionExpression`]).
    pub fn is_function(&self) -> bool {
        matches!(self, Expression::FunctionExpression(_) | Expression::ArrowFunctionExpression(_))
    }

    /// Returns `true` if this [`Expression`] is an anonymous function definition.
    /// Note that this includes [`Class`]s.
    /// <https://262.ecma-international.org/15.0/#sec-isanonymousfunctiondefinition>
    pub fn is_anonymous_function_definition(&self) -> bool {
        match self.without_parentheses() {
            Self::ArrowFunctionExpression(_) => true,
            Self::FunctionExpression(func) => func.name().is_none(),
            Self::ClassExpression(class) => class.name().is_none(),
            _ => false,
        }
    }

    /// Returns `true` if this [`Expression`] is a [`CallExpression`].
    pub fn is_call_expression(&self) -> bool {
        matches!(self, Expression::CallExpression(_))
    }

    /// Returns `true` if this [`Expression`] is a [`Super`].
    pub fn is_super(&self) -> bool {
        matches!(self, Expression::Super(_))
    }

    /// Returns `true` if this [`Expression`] is a [`CallExpression`] with [`Super`] as callee.
    pub fn is_super_call_expression(&self) -> bool {
        matches!(self, Expression::CallExpression(expr) if matches!(&expr.callee, Expression::Super(_)))
    }

    /// Returns `true` if this [`Expression`] is a [`CallExpression`], [`NewExpression`],
    /// or [`ImportExpression`].
    pub fn is_call_like_expression(&self) -> bool {
        self.is_call_expression()
            || matches!(self, Expression::NewExpression(_) | Expression::ImportExpression(_))
    }

    /// Returns `true` if this [`Expression`] is a [`BinaryExpression`] or [`LogicalExpression`].
    pub fn is_binaryish(&self) -> bool {
        matches!(self, Expression::BinaryExpression(_) | Expression::LogicalExpression(_))
    }

    /// Returns the [`MemberExpression`] if this expression is a [`MemberExpression`], contains a
    /// [`MemberExpression`], or is or part of a [`ChainExpression`] (such as `a?.b`),
    /// and returns `None` otherwise if this is not a member expression.
    pub fn get_member_expr(&self) -> Option<&MemberExpression<'a>> {
        match self.get_inner_expression() {
            Expression::ChainExpression(chain_expr) => chain_expr.expression.as_member_expression(),
            expr => expr.as_member_expression(),
        }
    }

    /// Returns `true` if this [`Expression`] is a `require` call.
    ///
    /// See [`CallExpression::is_require_call`] for details of the exact patterns that match.
    pub fn is_require_call(&self) -> bool {
        if let Self::CallExpression(call_expr) = self { call_expr.is_require_call() } else { false }
    }

    /// Returns `true` if this is an [assignment expression](AssignmentExpression).
    pub fn is_assignment(&self) -> bool {
        matches!(self, Expression::AssignmentExpression(_))
    }

    /// Is identifier or `a.b` expression where `a` is an identifier.
    pub fn is_entity_name_expression(&self) -> bool {
        // Special case: treat `this.B` like `this` was an identifier
        matches!(
            self.without_parentheses(),
            Expression::Identifier(_) | Expression::ThisExpression(_)
        ) || self.is_property_access_entity_name_expression()
    }

    /// `a.b` expression where `a` is an identifier.
    pub fn is_property_access_entity_name_expression(&self) -> bool {
        if let Expression::StaticMemberExpression(e) = self {
            e.object.is_entity_name_expression()
        } else {
            false
        }
    }
}

impl Display for IdentifierName<'_> {
    #[inline]
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.name.fmt(f)
    }
}

impl Display for IdentifierReference<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.name.fmt(f)
    }
}

impl Display for BindingIdentifier<'_> {
    #[inline]
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.name.fmt(f)
    }
}

impl ArrayExpressionElement<'_> {
    /// Returns `true` if this array expression element is an [elision](Elision).
    /// An elision is a comma in an array literal that is not followed by an expression.
    /// For example, in `[1, , 3]`, the second element is an elision.
    pub fn is_elision(&self) -> bool {
        matches!(self, Self::Elision(_))
    }

    /// Returns `true` if this array expression element is a [spread](SpreadElement).
    #[inline]
    pub fn is_spread(&self) -> bool {
        matches!(self, Self::SpreadElement(_))
    }
}

impl<'a> From<Argument<'a>> for ArrayExpressionElement<'a> {
    fn from(argument: Argument<'a>) -> Self {
        match argument {
            Argument::SpreadElement(spread) => Self::SpreadElement(spread),
            _ => Self::from(argument.into_expression()),
        }
    }
}

impl<'a> ObjectPropertyKind<'a> {
    /// Returns `true` if this object property is a [spread](SpreadElement).
    #[inline]
    pub fn is_spread(&self) -> bool {
        matches!(self, Self::SpreadProperty(_))
    }

    /// Returns [`Some`] for non-spread [object properties](ObjectProperty).
    #[inline]
    pub fn as_property(&self) -> Option<&ObjectProperty<'a>> {
        match self {
            Self::ObjectProperty(prop) => Some(prop),
            Self::SpreadProperty(_) => None,
        }
    }
}

impl<'a> PropertyKey<'a> {
    /// Returns the static name of this property, if it has one, or `None` otherwise.
    ///
    /// ## Example
    ///
    /// - `a: 1` in `{ a: 1 }` would return `a`
    /// - `#a: 1` in `class C { #a: 1 }` would return `None`
    /// - `'a': 1` in `{ 'a': 1 }` would return `a`
    /// - `[a]: 1` in `{ [a]: 1 }` would return `None`
    pub fn static_name(&self) -> Option<Cow<'a, str>> {
        match self {
            Self::StaticIdentifier(ident) => Some(Cow::Borrowed(ident.name.as_str())),
            Self::StringLiteral(lit) => Some(Cow::Borrowed(lit.value.as_str())),
            Self::RegExpLiteral(lit) => Some(Cow::Owned(lit.regex.to_string())),
            Self::NumericLiteral(lit) => Some(Cow::Owned(lit.value.to_string())),
            Self::BigIntLiteral(lit) => Some(Cow::Borrowed(lit.value.as_str())),
            Self::NullLiteral(_) => Some(Cow::Borrowed("null")),
            Self::TemplateLiteral(lit) => lit.single_quasi().map(Into::into),
            _ => None,
        }
    }

    /// Returns `true` if the static name of this property key is exactly equal to the given name.
    pub fn is_specific_static_name(&self, name: &str) -> bool {
        self.static_name().is_some_and(|n| n == name)
    }

    /// Returns `true` if this property key is an identifier, such as `a` in `{ a: 1 }` or
    /// `#a` in `class C { #a: 1 }`.
    pub fn is_identifier(&self) -> bool {
        matches!(self, Self::PrivateIdentifier(_) | Self::StaticIdentifier(_))
    }

    /// Returns `true` if this property key is a private identifier, such as `#a` in
    /// `class C { #a: 1 }`.
    pub fn is_private_identifier(&self) -> bool {
        matches!(self, Self::PrivateIdentifier(_))
    }

    /// Returns the name of this property key, if it is a private identifier, or `None` otherwise.
    ///
    /// ## Example
    ///
    /// - `#a: 1` in `class C { #a: 1 }` would return `a`
    /// - `a: 1` in `{ a: 1 }` would return `None`
    pub fn private_name(&self) -> Option<Atom<'a>> {
        match self {
            Self::PrivateIdentifier(ident) => Some(ident.name),
            _ => None,
        }
    }

    /// Returns the name of this property key if it is an identifier or literal value, or `None` otherwise.
    ///
    /// ## Example
    ///
    /// - `#a: 1` in `class C { #a: 1 }` would return `a`
    /// - `a: 1` in `{ a: 1 }` would return `a`
    /// - `'a': 1` in `{ 'a': 1 }` would return `a`
    /// - `[a]: 1` in `{ [a]: 1 }` would return `None`
    pub fn name(&self) -> Option<Cow<'a, str>> {
        if self.is_private_identifier() {
            self.private_name().map(|name| Cow::Borrowed(name.as_str()))
        } else {
            self.static_name()
        }
    }

    /// Returns `true` if this property key is exactly equal to the given identifier name.
    pub fn is_specific_id(&self, name: &str) -> bool {
        match self {
            PropertyKey::StaticIdentifier(ident) => ident.name == name,
            _ => false,
        }
    }

    /// Returns `true` if this property key is a string literal with the given value.
    pub fn is_specific_string_literal(&self, string: &str) -> bool {
        matches!(self, Self::StringLiteral(s) if s.value == string)
    }
}

impl PropertyKind {
    /// Returns `true` if this property is a getter or setter.
    ///
    /// Analogous to [`MethodDefinitionKind::is_accessor`].
    pub fn is_accessor(self) -> bool {
        matches!(self, Self::Get | Self::Set)
    }
}

impl<'a> TemplateLiteral<'a> {
    /// Returns `true` if this template literal is a [no-substitution template](https://tc39.es/ecma262/#prod-NoSubstitutionTemplate)
    /// (a template literal with no expressions in it).
    ///
    /// ## Example
    ///
    /// - `` `foo` `` => `true`
    /// - `` `foo${bar}qux` `` => `false`
    pub fn is_no_substitution_template(&self) -> bool {
        self.quasis.len() == 1
    }

    /// Get single quasi from `template`
    pub fn single_quasi(&self) -> Option<Atom<'a>> {
        if self.is_no_substitution_template() { self.quasis[0].value.cooked } else { None }
    }
}

impl<'a> MemberExpression<'a> {
    /// Returns `true` if this member expression is a [`MemberExpression::ComputedMemberExpression`]. For example, `a[b]`
    /// in `let a = { b: 1 }; a[b]` is a computed member expression.
    pub fn is_computed(&self) -> bool {
        matches!(self, MemberExpression::ComputedMemberExpression(_))
    }

    /// Returns `true` if this member expression is an optionally chained member expression. For example, `a?.b`
    /// in `let a = null; a?.b` is an optionally chained member expression.
    pub fn optional(&self) -> bool {
        match self {
            MemberExpression::ComputedMemberExpression(expr) => expr.optional,
            MemberExpression::StaticMemberExpression(expr) => expr.optional,
            MemberExpression::PrivateFieldExpression(expr) => expr.optional,
        }
    }

    /// Returns a reference to the [`Expression`] that is the object of this member expression.
    pub fn object(&self) -> &Expression<'a> {
        match self {
            MemberExpression::ComputedMemberExpression(expr) => &expr.object,
            MemberExpression::StaticMemberExpression(expr) => &expr.object,
            MemberExpression::PrivateFieldExpression(expr) => &expr.object,
        }
    }

    /// Returns a mutable reference to the [`Expression`] that is the object of this member expression.
    pub fn object_mut(&mut self) -> &mut Expression<'a> {
        match self {
            MemberExpression::ComputedMemberExpression(expr) => &mut expr.object,
            MemberExpression::StaticMemberExpression(expr) => &mut expr.object,
            MemberExpression::PrivateFieldExpression(expr) => &mut expr.object,
        }
    }

    /// Returns the static property name of this member expression, if it has one, or `None` otherwise.
    ///
    /// If you need the [`Span`] of the property name, use [`MemberExpression::static_property_info`] instead.
    ///
    /// ## Example
    ///
    /// - `a.b` would return `Some("b")`
    /// - `a["b"]` would return `Some("b")`
    /// - `a[b]` would return `None`
    /// - `a.#b` would return `None`
    pub fn static_property_name(&self) -> Option<&'a str> {
        match self {
            MemberExpression::ComputedMemberExpression(expr) => {
                expr.static_property_name().map(|name| name.as_str())
            }
            MemberExpression::StaticMemberExpression(expr) => Some(expr.property.name.as_str()),
            MemberExpression::PrivateFieldExpression(_) => None,
        }
    }

    /// Returns the static property name of this member expression, if it has one, along with the source code [`Span`],
    /// or `None` otherwise.
    ///
    /// If you don't need the [`Span`], use [`MemberExpression::static_property_name`] instead.
    pub fn static_property_info(&self) -> Option<(Span, &'a str)> {
        match self {
            MemberExpression::ComputedMemberExpression(expr) => match &expr.expression {
                Expression::StringLiteral(lit) => Some((lit.span, lit.value.as_str())),
                Expression::TemplateLiteral(lit) => {
                    if lit.quasis.len() == 1 {
                        lit.quasis[0].value.cooked.map(|cooked| (lit.span, cooked.as_str()))
                    } else {
                        None
                    }
                }
                _ => None,
            },
            MemberExpression::StaticMemberExpression(expr) => {
                Some((expr.property.span, expr.property.name.as_str()))
            }
            MemberExpression::PrivateFieldExpression(_) => None,
        }
    }

    /// Returns `true` if this member expression is a specific member access such as `a.b`, and takes
    /// into account whether it might also be an optionally chained member access such as `a?.b`.
    pub fn through_optional_is_specific_member_access(&self, object: &str, property: &str) -> bool {
        let object_matches = match self.object().without_parentheses() {
            Expression::ChainExpression(x) => match x.expression.member_expression() {
                None => false,
                Some(member_expr) => {
                    member_expr.object().without_parentheses().is_specific_id(object)
                }
            },
            x => x.is_specific_id(object),
        };

        let property_matches = self.static_property_name().is_some_and(|p| p == property);

        object_matches && property_matches
    }

    /// Whether it is a static member access `object.property`
    pub fn is_specific_member_access(&self, object: &str, property: &str) -> bool {
        self.object().is_specific_id(object)
            && self.static_property_name().is_some_and(|p| p == property)
    }
}

impl<'a> ComputedMemberExpression<'a> {
    /// Returns the static property name of this member expression, if it has one, or `None` otherwise.
    pub fn static_property_name(&self) -> Option<Atom<'a>> {
        match &self.expression {
            Expression::StringLiteral(lit) => Some(lit.value),
            Expression::TemplateLiteral(lit) if lit.quasis.len() == 1 => lit.quasis[0].value.cooked,
            Expression::RegExpLiteral(lit) => lit.raw,
            _ => None,
        }
    }

    /// Returns the static property name of this member expression, if it has one, along with the source code [`Span`],
    /// or `None` otherwise.
    /// If you don't need the [`Span`], use [`ComputedMemberExpression::static_property_name`] instead.
    pub fn static_property_info(&self) -> Option<(Span, &'a str)> {
        match &self.expression {
            Expression::StringLiteral(lit) => Some((lit.span, lit.value.as_str())),
            Expression::TemplateLiteral(lit) if lit.quasis.len() == 1 => {
                lit.quasis[0].value.cooked.map(|cooked| (lit.span, cooked.as_str()))
            }
            Expression::RegExpLiteral(lit) => lit.raw.map(|raw| (lit.span, raw.as_str())),
            _ => None,
        }
    }
}

impl<'a> StaticMemberExpression<'a> {
    /// Returns the first non-member expression in the chain of static member expressions. For example, will return `a` for `a?.b?.c`.
    pub fn get_first_object(&self) -> &Expression<'a> {
        let mut object = &self.object;
        loop {
            match object {
                Expression::StaticMemberExpression(member) => {
                    object = &member.object;
                    continue;
                }
                Expression::ChainExpression(chain) => {
                    if let ChainElement::StaticMemberExpression(member) = &chain.expression {
                        object = &member.object;
                        continue;
                    }
                }
                _ => {}
            }

            return object;
        }
    }

    /// Returns the static property name of this static member expression, if it has one, along with the source code [`Span`],
    /// or `None` otherwise.
    pub fn static_property_info(&self) -> (Span, &'a str) {
        (self.property.span, self.property.name.as_str())
    }
}

impl<'a> ChainElement<'a> {
    /// Returns the member expression.
    pub fn member_expression(&self) -> Option<&MemberExpression<'a>> {
        match self {
            ChainElement::TSNonNullExpression(e) => match &e.expression {
                match_member_expression!(Expression) => e.expression.as_member_expression(),
                _ => None,
            },
            _ => self.as_member_expression(),
        }
    }
}

impl<'a> From<ChainElement<'a>> for Expression<'a> {
    fn from(value: ChainElement<'a>) -> Self {
        match value {
            ChainElement::CallExpression(e) => Expression::CallExpression(e),
            ChainElement::TSNonNullExpression(e) => Expression::TSNonNullExpression(e),
            match_member_expression!(ChainElement) => {
                Expression::from(value.into_member_expression())
            }
        }
    }
}

impl CallExpression<'_> {
    /// Returns the static name of the callee, if it has one, or `None` otherwise.
    pub fn callee_name(&self) -> Option<&str> {
        match &self.callee {
            Expression::Identifier(ident) => Some(ident.name.as_str()),
            expr => expr.as_member_expression().and_then(MemberExpression::static_property_name),
        }
    }

    /// Returns `true` if this [`CallExpression`] matches one of these patterns:
    /// ```js
    /// require('string')
    /// require(`string`)
    /// require(`foo${bar}qux`) // Any number of expressions and quasis
    /// ```
    pub fn is_require_call(&self) -> bool {
        if self.arguments.len() != 1 {
            return false;
        }
        if let Expression::Identifier(id) = &self.callee {
            id.name == "require"
                && matches!(
                    self.arguments.first(),
                    Some(Argument::StringLiteral(_) | Argument::TemplateLiteral(_)),
                )
        } else {
            false
        }
    }

    /// Returns `true` if this [`CallExpression`] is a call to `Symbol`
    /// or [`Symbol.for`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/for).
    pub fn is_symbol_or_symbol_for_call(&self) -> bool {
        // TODO: is 'Symbol' reference to global object
        match &self.callee {
            Expression::Identifier(id) => id.name == "Symbol",
            expr => match expr.as_member_expression() {
                Some(member) => {
                    matches!(member.object(), Expression::Identifier(id) if id.name == "Symbol")
                        && member.static_property_name() == Some("for")
                }
                None => false,
            },
        }
    }

    /// Returns `true` if this looks like a call to `require` in CommonJS (has a single string argument):
    /// ```js
    /// require('string') // => true
    /// require('string', 'string') // => false
    /// require() // => false
    /// require(123) // => false
    /// ```
    pub fn common_js_require(&self) -> Option<&StringLiteral<'_>> {
        if !(self.callee.is_specific_id("require") && self.arguments.len() == 1) {
            return None;
        }
        match &self.arguments[0] {
            Argument::StringLiteral(str_literal) => Some(str_literal),
            _ => None,
        }
    }

    /// Returns the span covering **all** arguments in this call expression.
    ///
    /// The span starts at the beginning of the first argument and ends at the end
    /// of the last argument (inclusive).
    ///
    /// # Examples
    /// ```ts
    /// foo(bar, baz);
    /// //  ^^^^^^^^  <- arguments_span() covers this range
    /// ```
    ///
    /// If the call expression has no arguments, [`None`] is returned.
    pub fn arguments_span(&self) -> Option<Span> {
        self.arguments.first().map(|first| {
            // The below will never panic since the len of `self.arguments` must be >= 1
            #[expect(clippy::missing_panics_doc)]
            let last = self.arguments.last().unwrap();
            Span::new(first.span().start, last.span().end)
        })
    }
}

impl NewExpression<'_> {
    /// Returns the span covering **all** arguments in this new call expression.
    ///
    /// The span starts at the beginning of the first argument and ends at the end
    /// of the last argument (inclusive).
    ///
    /// # Examples
    /// ```ts
    /// new Foo(bar, baz);
    /// //      ^^^^^^^^  <- arguments_span() covers this range
    /// ```
    ///
    /// If the new expression has no arguments, [`None`] is returned.
    pub fn arguments_span(&self) -> Option<Span> {
        self.arguments.first().map(|first| {
            // The below will never panic since the len of `self.arguments` must be >= 1
            #[expect(clippy::missing_panics_doc)]
            let last = self.arguments.last().unwrap();
            Span::new(first.span().start, last.span().end)
        })
    }
}

impl Argument<'_> {
    /// Returns `true` if this argument is a spread element (like `...foo`).
    pub fn is_spread(&self) -> bool {
        matches!(self, Self::SpreadElement(_))
    }
}

impl<'a> AssignmentTarget<'a> {
    /// Returns the identifier name of this assignment target when it is simple like `a = b`.
    ///
    /// ## Example
    ///
    /// - returns `a` when called on the left-hand side of `a = b`
    /// - returns `b` when called on the left-hand side of `a.b = b`
    /// - returns `None` when called on the left-hand side of `a[b] = b`
    pub fn get_identifier_name(&self) -> Option<&'a str> {
        self.as_simple_assignment_target().and_then(SimpleAssignmentTarget::get_identifier_name)
    }

    /// Returns the expression inside of this assignment target, if applicable, and returns a reference to it.
    ///
    /// For getting a mutable reference of the expression inside, use [`AssignmentTarget::get_expression_mut`].
    ///
    /// ## Example
    ///
    /// - returns `a` when called on `a!` in `a! = b`
    /// - returns `None` when called on `a` in `a = b` because there is no inner expression to get
    pub fn get_expression(&self) -> Option<&Expression<'a>> {
        self.as_simple_assignment_target().and_then(SimpleAssignmentTarget::get_expression)
    }

    /// Returns the expression inside of this assignment target, if applicable, and returns a mutable reference to it.
    ///
    /// For getting an immutable reference of the expression inside, use [`AssignmentTarget::get_expression`].
    ///
    /// ## Example
    ///
    /// - returns `a` when called on `a!` in `a! = b`
    /// - returns `None` when called on `a` in `a = b` because there is no inner expression to get
    pub fn get_expression_mut(&mut self) -> Option<&mut Expression<'a>> {
        self.as_simple_assignment_target_mut().and_then(SimpleAssignmentTarget::get_expression_mut)
    }
}

impl<'a> SimpleAssignmentTarget<'a> {
    /// Returns the identifier name of this assignment target if the target is an identifier or
    /// a member expression, or `None` otherwise.
    ///
    /// ## Example
    ///
    /// - returns identifier `a` when called on the left-hand side of `a = b`
    /// - returns identifier `b` when called on the left-hand side of `a.b = b`
    /// - returns `None` when called on the left-hand side of `a[b] = b` because it is not an identifier
    pub fn get_identifier_name(&self) -> Option<&'a str> {
        match self {
            Self::AssignmentTargetIdentifier(ident) => Some(ident.name.as_str()),
            match_member_expression!(Self) => self.to_member_expression().static_property_name(),
            _ => None,
        }
    }

    /// Returns the expression inside of this assignment target, if applicable, and returns a reference to it.
    ///
    /// ## Example
    ///
    /// - returns `a` when called on `a!` in `a! = b`
    /// - returns `None` when called on `a` in `a = b` because there is no inner expression to get
    pub fn get_expression(&self) -> Option<&Expression<'a>> {
        match self {
            Self::TSAsExpression(expr) => Some(&expr.expression),
            Self::TSSatisfiesExpression(expr) => Some(&expr.expression),
            Self::TSNonNullExpression(expr) => Some(&expr.expression),
            Self::TSTypeAssertion(expr) => Some(&expr.expression),
            _ => None,
        }
    }

    /// Returns the expression inside of this assignment target, if applicable, and returns a mutable reference to it.
    ///
    /// For getting an immutable reference of the expression inside, use [`SimpleAssignmentTarget::get_expression`].
    ///
    /// ## Example
    ///
    /// - returns `a` when called on `a!` in `a! = b`
    /// - returns `None` when called on `a` in `a = b` because there is no inner expression to get
    pub fn get_expression_mut(&mut self) -> Option<&mut Expression<'a>> {
        match self {
            Self::TSAsExpression(expr) => Some(&mut expr.expression),
            Self::TSSatisfiesExpression(expr) => Some(&mut expr.expression),
            Self::TSNonNullExpression(expr) => Some(&mut expr.expression),
            Self::TSTypeAssertion(expr) => Some(&mut expr.expression),
            _ => None,
        }
    }
}

impl ObjectAssignmentTarget<'_> {
    /// Returns `true` if this object assignment target is empty.
    ///
    /// ## Example
    ///
    /// - `{}` => `true`
    /// - `{a}` => `false`
    /// - `{...a}` => `false`
    pub fn is_empty(&self) -> bool {
        self.properties.is_empty() && self.rest.is_none()
    }

    /// Returns the number of identifiers in this object assignment target.
    ///
    /// ## Example
    ///
    /// - `{}` => `0`
    /// - `{a}` => `1`
    /// - `{...a}` => `1`
    /// - `{a, b}` => `2`
    /// - `{a, b, ...c}` => `3`
    pub fn len(&self) -> usize {
        self.properties.len() + usize::from(self.rest.is_some())
    }
}

impl<'a> AssignmentTargetMaybeDefault<'a> {
    /// Returns the identifier bound by this assignment target.
    ///
    /// ## Example
    ///
    /// - returns `b` when called on `a: b = 1` in `({a: b = 1} = obj)`
    /// - returns `b` when called on `a: b` in `({a: b} = obj)`
    pub fn identifier(&self) -> Option<&IdentifierReference<'a>> {
        match self {
            AssignmentTargetMaybeDefault::AssignmentTargetIdentifier(id) => Some(id),
            Self::AssignmentTargetWithDefault(target) => {
                if let AssignmentTarget::AssignmentTargetIdentifier(id) = &target.binding {
                    Some(id)
                } else {
                    None
                }
            }
            _ => None,
        }
    }

    /// Returns mut identifier bound by this assignment target.
    pub fn identifier_mut(&mut self) -> Option<&mut IdentifierReference<'a>> {
        match self {
            AssignmentTargetMaybeDefault::AssignmentTargetIdentifier(id) => Some(id),
            Self::AssignmentTargetWithDefault(target) => {
                if let AssignmentTarget::AssignmentTargetIdentifier(id) = &mut target.binding {
                    Some(id)
                } else {
                    None
                }
            }
            _ => None,
        }
    }
}

impl Statement<'_> {
    /// Returns `true` if this statement uses any TypeScript syntax (such as `declare`).
    pub fn is_typescript_syntax(&self) -> bool {
        match self {
            match_declaration!(Self) => {
                self.as_declaration().is_some_and(Declaration::is_typescript_syntax)
            }
            match_module_declaration!(Self) => {
                self.as_module_declaration().is_some_and(ModuleDeclaration::is_typescript_syntax)
            }
            _ => false,
        }
    }

    /// Returns `true` if this statement uses iteration like `do`, `for`, or `while`.
    ///
    /// ## Example
    ///
    /// - `do { } while (true)` => `true`
    /// - `for (let i = 0; i < 10; i++) { }` => `true`
    /// - `for (let i in obj) { }` => `true`
    /// - `for (let i of obj) { }` => `true`
    /// - `while (true) { }` => `true`
    /// - `if (true) { }` => `false`
    pub fn is_iteration_statement(&self) -> bool {
        matches!(
            self,
            Statement::DoWhileStatement(_)
                | Statement::ForInStatement(_)
                | Statement::ForOfStatement(_)
                | Statement::ForStatement(_)
                | Statement::WhileStatement(_)
        )
    }

    /// Returns `true` if this statement affects control flow, such as `return`, `throw`, `break`, or `continue`.
    ///
    /// ## Example
    ///
    /// - `return true` => `true`
    /// - `throw new Error()` => `true`
    /// - `break` => `true`
    /// - `continue` => `true`
    /// - `if (true) { }` => `false`
    pub fn is_jump_statement(&self) -> bool {
        self.get_one_child().is_some_and(|stmt| {
            matches!(
                stmt,
                Self::ReturnStatement(_)
                    | Self::ThrowStatement(_)
                    | Self::BreakStatement(_)
                    | Self::ContinueStatement(_)
            )
        })
    }

    /// Returns the single statement from block statement, or self
    pub fn get_one_child(&self) -> Option<&Self> {
        if let Statement::BlockStatement(block_stmt) = self {
            return (block_stmt.body.len() == 1).then(|| &block_stmt.body[0]);
        }
        Some(self)
    }

    /// Returns the single statement from block statement, or self
    pub fn get_one_child_mut(&mut self) -> Option<&mut Self> {
        if let Statement::BlockStatement(block_stmt) = self {
            return (block_stmt.body.len() == 1).then_some(&mut block_stmt.body[0]);
        }
        Some(self)
    }
}

impl Directive<'_> {
    /// A Use Strict Directive is an ExpressionStatement in a Directive Prologue whose StringLiteral is either of the exact code point sequences "use strict" or 'use strict'.
    /// A Use Strict Directive may not contain an EscapeSequence or LineContinuation.
    /// <https://tc39.es/ecma262/#sec-directive-prologues-and-the-use-strict-directive>
    pub fn is_use_strict(&self) -> bool {
        self.directive == "use strict"
    }
}

impl<'a> Declaration<'a> {
    /// Returns `true` if this declaration uses any TypeScript syntax such as `declare`, abstract classes, or function overload signatures.
    pub fn is_typescript_syntax(&self) -> bool {
        match self {
            Self::VariableDeclaration(decl) => decl.is_typescript_syntax(),
            Self::FunctionDeclaration(func) => func.is_typescript_syntax(),
            Self::ClassDeclaration(class) => class.is_typescript_syntax(),
            _ => true,
        }
    }

    /// Get the identifier bound by this declaration.
    ///
    /// ## Example
    /// ```ts
    /// const x = 1; // None. may change in the future.
    /// class Foo {} // Some(IdentifierReference { name: "Foo", .. })
    /// enum Bar {} // Some(IdentifierReference { name: "Bar", .. })
    /// declare global {} // None
    /// ```
    pub fn id(&self) -> Option<&BindingIdentifier<'a>> {
        match self {
            Declaration::FunctionDeclaration(decl) => decl.id.as_ref(),
            Declaration::ClassDeclaration(decl) => decl.id.as_ref(),
            Declaration::TSTypeAliasDeclaration(decl) => Some(&decl.id),
            Declaration::TSInterfaceDeclaration(decl) => Some(&decl.id),
            Declaration::TSEnumDeclaration(decl) => Some(&decl.id),
            Declaration::TSImportEqualsDeclaration(decl) => Some(&decl.id),
            Declaration::TSModuleDeclaration(decl) => {
                if let TSModuleDeclarationName::Identifier(ident) = &decl.id {
                    Some(ident)
                } else {
                    None
                }
            }
            Declaration::TSGlobalDeclaration(_) | Declaration::VariableDeclaration(_) => None,
        }
    }

    /// Returns `true` if this declaration was made using the `declare` keyword in TypeScript.
    pub fn declare(&self) -> bool {
        match self {
            Declaration::VariableDeclaration(decl) => decl.declare,
            Declaration::FunctionDeclaration(decl) => decl.declare,
            Declaration::ClassDeclaration(decl) => decl.declare,
            Declaration::TSEnumDeclaration(decl) => decl.declare,
            Declaration::TSTypeAliasDeclaration(decl) => decl.declare,
            Declaration::TSModuleDeclaration(decl) => decl.declare,
            Declaration::TSGlobalDeclaration(decl) => decl.declare,
            Declaration::TSInterfaceDeclaration(decl) => decl.declare,
            Declaration::TSImportEqualsDeclaration(_) => false,
        }
    }

    /// Returns `true` if this declaration is a TypeScript type or interface declaration.
    pub fn is_type(&self) -> bool {
        matches!(self, Self::TSTypeAliasDeclaration(_) | Self::TSInterfaceDeclaration(_))
    }
}

impl VariableDeclaration<'_> {
    /// Returns `true` if this declaration uses the `declare` TypeScript syntax.
    pub fn is_typescript_syntax(&self) -> bool {
        self.declare
    }

    /// Returns `true` if any of this declaration's variables have an initializer.
    pub fn has_init(&self) -> bool {
        self.declarations.iter().any(|decl| decl.init.is_some())
    }
}

impl VariableDeclarationKind {
    /// Returns `true` if declared using `var` (such as `var x`)
    pub fn is_var(self) -> bool {
        self == Self::Var
    }

    /// Returns `true` if declared using `const` (such as `const x`)
    pub fn is_const(self) -> bool {
        self == Self::Const
    }

    /// Returns `true` if declared using `let`, `const` or `using` (such as `let x` or `const x`)
    pub fn is_lexical(self) -> bool {
        matches!(self, Self::Const | Self::Let | Self::Using | Self::AwaitUsing)
    }

    /// Returns `true` if declared with `using` (such as `using x` or `await using x`)
    pub fn is_using(self) -> bool {
        self == Self::Using || self == Self::AwaitUsing
    }

    /// Returns `true` if declared using `await using` (such as `await using x`)
    pub fn is_await(self) -> bool {
        self == Self::AwaitUsing
    }

    /// Returns the code syntax for this [`VariableDeclarationKind`].
    ///
    /// For example, [`Var`][`VariableDeclarationKind::Var`] returns `"var"`,
    /// [`AwaitUsing`][`VariableDeclarationKind::AwaitUsing`] returns `"await using"`.
    pub fn as_str(self) -> &'static str {
        match self {
            Self::Var => "var",
            Self::Const => "const",
            Self::Let => "let",
            Self::Using => "using",
            Self::AwaitUsing => "await using",
        }
    }
}

impl Display for VariableDeclarationKind {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.as_str().fmt(f)
    }
}

impl ForStatementInit<'_> {
    /// Is `var` declaration
    pub fn is_var_declaration(&self) -> bool {
        matches!(self, Self::VariableDeclaration(decl) if decl.kind.is_var())
    }

    /// LexicalDeclaration[In, Yield, Await] :
    ///   LetOrConst BindingList[?In, ?Yield, ?Await] ;
    ///   UsingDeclaration[?In, ?Yield, ?Await]
    ///   [+Await] AwaitUsingDeclaration[?In, ?Yield]
    pub fn is_lexical_declaration(&self) -> bool {
        matches!(self, Self::VariableDeclaration(decl) if decl.kind.is_lexical())
    }
}

impl ForStatementLeft<'_> {
    /// LexicalDeclaration[In, Yield, Await] :
    ///   LetOrConst BindingList[?In, ?Yield, ?Await] ;
    ///   UsingDeclaration[?In, ?Yield, ?Await]
    ///   [+Await] AwaitUsingDeclaration[?In, ?Yield]
    pub fn is_lexical_declaration(&self) -> bool {
        matches!(self, Self::VariableDeclaration(decl) if decl.kind.is_lexical())
    }
}

impl SwitchCase<'_> {
    /// `true` for `default:` cases.
    pub fn is_default_case(&self) -> bool {
        self.test.is_none()
    }
}

impl<'a> BindingPattern<'a> {
    /// Returns the name of the bound identifier in this binding pattern, if it has one, or `None` otherwise.
    ///
    /// ## Example
    ///
    /// - calling on `a = 1` in `let a = 1` would return `Some("a")`
    /// - calling on `a = 1` in `let {a = 1} = c` would return `Some("a")`
    /// - calling on `a: b` in `let {a: b} = c` would return `None`
    pub fn get_identifier_name(&self) -> Option<Atom<'a>> {
        self.kind.get_identifier_name()
    }

    /// Returns the bound identifier in this binding pattern, if it has one, or `None` otherwise.
    ///
    /// To just get the name of the bound identifier, use [`BindingPattern::get_identifier_name`].
    ///
    /// ## Example
    ///
    /// - calling on `a = 1` in `let a = 1` would return `Some(BindingIdentifier { name: "a", .. })`
    /// - calling on `a = 1` in `let {a = 1} = c` would return `Some(BindingIdentifier { name: "a", .. })`
    /// - calling on `a: b` in `let {a: b} = c` would return `None`
    pub fn get_binding_identifier(&self) -> Option<&BindingIdentifier<'a>> {
        self.kind.get_binding_identifier()
    }

    /// Returns the bound identifiers in this binding pattern.
    ///
    /// ## Example
    ///
    /// - `let {} = obj` would return `[]`
    /// - `let {a, b} = obj` would return `[a, b]`
    /// - `let {a = 1, b: c} = obj` would return `[a, c]`
    pub fn get_binding_identifiers(&self) -> std::vec::Vec<&BindingIdentifier<'a>> {
        self.kind.get_binding_identifiers()
    }
}

impl<'a> BindingPatternKind<'a> {
    /// Returns the name of the bound identifier in this binding pattern, if it has one, or `None` otherwise.
    ///
    /// ## Example
    ///
    /// - calling on `a = 1` in `let a = 1` would return `Some("a")`
    /// - calling on `a = 1` in `let {a = 1} = c` would return `Some("a")`
    /// - calling on `a: b` in `let {a: b} = c` would return `None`
    pub fn get_identifier_name(&self) -> Option<Atom<'a>> {
        match self {
            Self::BindingIdentifier(ident) => Some(ident.name),
            Self::AssignmentPattern(assign) => assign.left.get_identifier_name(),
            _ => None,
        }
    }

    /// Returns the bound identifier in this binding pattern, if it has one, or `None` otherwise.
    ///
    /// To just get the name of the bound identifier, use [`BindingPatternKind::get_identifier_name`].
    ///
    /// ## Example
    ///
    /// - calling on `a = 1` in `let a = 1` would return `Some(BindingIdentifier { name: "a", .. })`
    /// - calling on `a = 1` in `let {a = 1} = c` would return `Some(BindingIdentifier { name: "a", .. })`
    /// - calling on `a: b` in `let {a: b} = c` would return `None`
    pub fn get_binding_identifier(&self) -> Option<&BindingIdentifier<'a>> {
        match self {
            Self::BindingIdentifier(ident) => Some(ident),
            Self::AssignmentPattern(assign) => assign.left.get_binding_identifier(),
            _ => None,
        }
    }

    fn append_binding_identifiers<'b>(
        &'b self,
        idents: &mut std::vec::Vec<&'b BindingIdentifier<'a>>,
    ) {
        match self {
            Self::BindingIdentifier(ident) => idents.push(ident),
            Self::AssignmentPattern(assign) => assign.left.kind.append_binding_identifiers(idents),
            Self::ArrayPattern(pattern) => {
                pattern
                    .elements
                    .iter()
                    .filter_map(|item| item.as_ref())
                    .for_each(|item| item.kind.append_binding_identifiers(idents));
                if let Some(rest) = &pattern.rest {
                    rest.argument.kind.append_binding_identifiers(idents);
                }
            }
            Self::ObjectPattern(pattern) => {
                pattern.properties.iter().for_each(|item| {
                    item.value.kind.append_binding_identifiers(idents);
                });
                if let Some(rest) = &pattern.rest {
                    rest.argument.kind.append_binding_identifiers(idents);
                }
            }
        }
    }

    /// Returns the bound identifiers in this binding pattern.
    ///
    /// ## Example
    ///
    /// - `let {} = obj` would return `[]`
    /// - `let {a, b} = obj` would return `[a, b]`
    /// - `let {a = 1, b: c} = obj` would return `[a, c]`
    pub fn get_binding_identifiers(&self) -> std::vec::Vec<&BindingIdentifier<'a>> {
        let mut idents = vec![];
        self.append_binding_identifiers(&mut idents);
        idents
    }

    /// Returns `true` if this binding pattern is destructuring.
    ///
    /// ## Example
    ///
    /// - `{a, b}` in `let {a, b} = obj` would return `true`
    /// - `[a, b]` in `let [a, b] = arr` would return `true`
    /// - `a = 1` in `let {a = 1} = obj` would return `true`
    /// - `a` in `let {a = 1} = obj` would return `false`
    pub fn is_destructuring_pattern(&self) -> bool {
        match self {
            Self::ObjectPattern(_) | Self::ArrayPattern(_) => true,
            Self::AssignmentPattern(pattern) => pattern.left.kind.is_destructuring_pattern(),
            Self::BindingIdentifier(_) => false,
        }
    }

    /// Returns `true` if this binding pattern is a binding identifier like `a` in `let a = 1`.
    pub fn is_binding_identifier(&self) -> bool {
        matches!(self, Self::BindingIdentifier(_))
    }

    /// Returns `true` if this binding pattern is an object pattern like `{a}` in `let {a} = obj`.
    pub fn is_object_pattern(&self) -> bool {
        matches!(self, Self::ObjectPattern(_))
    }

    /// Returns `true` if this binding pattern is an array pattern like `[a]` in `let [a] = arr`.
    pub fn is_array_pattern(&self) -> bool {
        matches!(self, Self::ArrayPattern(_))
    }

    /// Returns `true` if this binding pattern is an assignment pattern like `a = 1` in `let {a = 1} = obj`.
    pub fn is_assignment_pattern(&self) -> bool {
        matches!(self, Self::AssignmentPattern(_))
    }
}

impl ObjectPattern<'_> {
    /// `true` for empty object patterns (`{}`).
    pub fn is_empty(&self) -> bool {
        self.properties.is_empty() && self.rest.is_none()
    }

    /// The number of properties, including rest properties, in this object pattern.
    pub fn len(&self) -> usize {
        self.properties.len() + usize::from(self.rest.is_some())
    }
}

impl ArrayPattern<'_> {
    /// `true` for empty array patterns (`[]`).
    pub fn is_empty(&self) -> bool {
        self.elements.is_empty() && self.rest.is_none()
    }

    /// The number of elements, including rest elements, in this array pattern.
    pub fn len(&self) -> usize {
        self.elements.len() + usize::from(self.rest.is_some())
    }
}

impl<'a> Function<'a> {
    /// Returns this [`Function`]'s name, if it has one.
    #[inline]
    pub fn name(&self) -> Option<Atom<'a>> {
        self.id.as_ref().map(|id| id.name)
    }

    /// Returns `true` if this function uses overload signatures or `declare function` statements.
    pub fn is_typescript_syntax(&self) -> bool {
        self.r#type.is_typescript_syntax() || self.body.is_none() || self.declare
    }

    /// `true` for both function expressions and typescript empty body function expressions
    pub fn is_expression(&self) -> bool {
        self.r#type == FunctionType::FunctionExpression
            || self.r#type == FunctionType::TSEmptyBodyFunctionExpression
    }

    /// `true` for function declarations
    pub fn is_function_declaration(&self) -> bool {
        matches!(self.r#type, FunctionType::FunctionDeclaration)
    }

    /// `true` for `declare function` statements
    pub fn is_ts_declare_function(&self) -> bool {
        matches!(self.r#type, FunctionType::TSDeclareFunction)
    }

    /// `true` for non-expression functions
    pub fn is_declaration(&self) -> bool {
        matches!(self.r#type, FunctionType::FunctionDeclaration | FunctionType::TSDeclareFunction)
    }

    /// Returns `true` if this function's body has a `"use strict"` directive.
    pub fn has_use_strict_directive(&self) -> bool {
        self.body.as_ref().is_some_and(|body| body.has_use_strict_directive())
    }
}

impl FunctionType {
    /// Returns `true` if it is a [`FunctionType::TSDeclareFunction`] or [`FunctionType::TSEmptyBodyFunctionExpression`].
    pub fn is_typescript_syntax(self) -> bool {
        matches!(self, Self::TSDeclareFunction | Self::TSEmptyBodyFunctionExpression)
    }
}

impl<'a> FormalParameters<'a> {
    /// Number of parameters bound in this parameter list.
    pub fn parameters_count(&self) -> usize {
        self.items.len() + self.rest.as_ref().map_or(0, |_| 1)
    }

    /// Iterates over all bound parameters, including rest parameters.
    pub fn iter_bindings(&self) -> impl Iterator<Item = &BindingPattern<'a>> + '_ {
        self.items
            .iter()
            .map(|param| &param.pattern)
            .chain(self.rest.iter().map(|rest| &rest.argument))
    }
}

impl FormalParameter<'_> {
    /// `true` if a `public` accessibility modifier is present. Use
    /// [`has_modifier`](FormalParameter::has_modifier) if you want to check for
    /// _any_ modifier, including `readonly` and `override`.
    ///
    /// ## Example
    /// ```ts
    /// class Foo {
    ///     constructor(
    ///         public x: number,  // <- true
    ///         private y: string, // <- false
    ///         z: string          // <- false
    ///     ) {}
    /// }
    pub fn is_public(&self) -> bool {
        matches!(self.accessibility, Some(TSAccessibility::Public))
    }

    /// `true` if any modifier, accessibility or otherwise, is present.
    ///
    /// ## Example
    /// ```ts
    /// class Foo {
    ///     constructor(
    ///         public a: number,   // <- true
    ///         readonly b: string, // <- true
    ///         override c: string, // <- true
    ///         d: string           // <- false
    ///    ) {}
    /// }
    /// ```
    #[inline]
    pub fn has_modifier(&self) -> bool {
        self.accessibility.is_some() || self.readonly || self.r#override
    }
}

impl FormalParameterKind {
    /// `true` when part of a TypeScript method or function signature.
    pub fn is_signature(self) -> bool {
        self == Self::Signature
    }
}

impl FormalParameters<'_> {
    /// `true` if no parameters are bound.
    pub fn is_empty(&self) -> bool {
        self.items.is_empty()
    }

    /// `true` if at least one parameter is bound, including [rest bindings](BindingRestElement).
    pub fn has_parameter(&self) -> bool {
        !self.is_empty() || self.rest.is_some()
    }
}

impl FunctionBody<'_> {
    /// `true` if this function body contains no statements or directives.
    pub fn is_empty(&self) -> bool {
        self.directives.is_empty() && self.statements.is_empty()
    }

    /// `true` if this function body contains a `"use strict"` directive.
    pub fn has_use_strict_directive(&self) -> bool {
        self.directives.iter().any(Directive::is_use_strict)
    }
}

impl<'a> ArrowFunctionExpression<'a> {
    /// Get expression part of `ArrowFunctionExpression`: `() => expression_part`.
    pub fn get_expression(&self) -> Option<&Expression<'a>> {
        if self.expression
            && let Statement::ExpressionStatement(expr_stmt) = &self.body.statements[0]
        {
            return Some(&expr_stmt.expression);
        }
        None
    }

    /// Get expression part of `ArrowFunctionExpression`: `() => expression_part`.
    pub fn get_expression_mut(&mut self) -> Option<&mut Expression<'a>> {
        if self.expression
            && let Statement::ExpressionStatement(expr_stmt) = &mut self.body.statements[0]
        {
            return Some(&mut expr_stmt.expression);
        }
        None
    }

    /// Returns `true` if this arrow function's body has a `"use strict"` directive.
    pub fn has_use_strict_directive(&self) -> bool {
        self.body.has_use_strict_directive()
    }
}

impl<'a> Class<'a> {
    /// Returns this [`Class`]'s name, if it has one.
    #[inline]
    pub fn name(&self) -> Option<Atom<'a>> {
        self.id.as_ref().map(|id| id.name)
    }

    /// `true` if this [`Class`] is an expression.
    ///
    /// For example,
    /// ```ts
    /// var Foo = class { /* ... */ }
    /// ```
    pub fn is_expression(&self) -> bool {
        self.r#type == ClassType::ClassExpression
    }

    /// `true` if this [`Class`] is a declaration statement.
    ///
    /// For example,
    /// ```ts
    /// class Foo {
    ///   // ...
    /// }
    /// ```
    pub fn is_declaration(&self) -> bool {
        self.r#type == ClassType::ClassDeclaration
    }

    /// Returns `true` if this class uses `declare class` or `abstract class` syntax.
    pub fn is_typescript_syntax(&self) -> bool {
        self.declare || self.r#abstract
    }
}

impl<'a> ClassElement<'a> {
    /// Returns `true` if this is a [`ClassElement::StaticBlock`].
    pub fn is_static_block(&self) -> bool {
        matches!(self, Self::StaticBlock(_))
    }

    /// Returns `true` if this [`ClassElement`] has a static modifier.
    ///
    /// Note: Class static blocks do not have a "modifier", as there is no non-static equivalent.
    /// Therefore, returns `false` for static blocks.
    ///
    /// The following all return `true`:
    /// ```ts
    /// class {
    ///   static prop = 1;
    ///   static method() {}
    ///   static #private = 2;
    ///   static #privateMethod() {}
    ///   static accessor accessorProp = 3;
    ///   static accessor #privateAccessorProp = 4;
    /// }
    /// ```
    pub fn r#static(&self) -> bool {
        match self {
            Self::TSIndexSignature(_) | Self::StaticBlock(_) => false,
            Self::MethodDefinition(def) => def.r#static,
            Self::PropertyDefinition(def) => def.r#static,
            Self::AccessorProperty(def) => def.r#static,
        }
    }

    /// Returns `true` if this [`ClassElement`] is computed.
    ///
    /// The following all return `true`:
    /// ```ts
    /// class C {
    ///   [a] = 1;
    ///   [b]() {}
    ///   accessor [c] = 2;
    /// }
    /// ```
    pub fn computed(&self) -> bool {
        match self {
            Self::TSIndexSignature(_) | Self::StaticBlock(_) => false,
            Self::MethodDefinition(def) => def.computed,
            Self::PropertyDefinition(def) => def.computed,
            Self::AccessorProperty(def) => def.computed,
        }
    }

    /// Returns the [accessibility][`TSAccessibility`] of this [`ClassElement`], if any is indicated.
    pub fn accessibility(&self) -> Option<TSAccessibility> {
        match self {
            Self::StaticBlock(_) | Self::TSIndexSignature(_) | Self::AccessorProperty(_) => None,
            Self::MethodDefinition(def) => def.accessibility,
            Self::PropertyDefinition(def) => def.accessibility,
        }
    }

    /// Returns whether this [`ClassElement`] method is a constructor, method, getter, or setter,
    /// or `None` otherwise if it is not a method definition.
    pub fn method_definition_kind(&self) -> Option<MethodDefinitionKind> {
        match self {
            Self::TSIndexSignature(_)
            | Self::StaticBlock(_)
            | Self::PropertyDefinition(_)
            | Self::AccessorProperty(_) => None,
            Self::MethodDefinition(def) => Some(def.kind),
        }
    }

    /// Returns the [`PropertyKey`] of this [`ClassElement`], if any.
    ///
    /// This is either the name of the method, property name, or accessor name.
    pub fn property_key(&self) -> Option<&PropertyKey<'a>> {
        match self {
            Self::TSIndexSignature(_) | Self::StaticBlock(_) => None,
            Self::MethodDefinition(def) => Some(&def.key),
            Self::PropertyDefinition(def) => Some(&def.key),
            Self::AccessorProperty(def) => Some(&def.key),
        }
    }

    /// Try to get the statically known name of this [`ClassElement`]. Handles
    /// computed members that use literals.
    pub fn static_name(&self) -> Option<Cow<'a, str>> {
        match self {
            Self::TSIndexSignature(_) | Self::StaticBlock(_) => None,
            Self::MethodDefinition(def) => def.key.static_name(),
            Self::PropertyDefinition(def) => def.key.static_name(),
            Self::AccessorProperty(def) => def.key.static_name(),
        }
    }

    /// Returns `true` if this [`ClassElement`] is a property or accessor
    pub fn is_property(&self) -> bool {
        matches!(self, Self::PropertyDefinition(_) | Self::AccessorProperty(_))
    }

    /// `true` for overloads, declarations, index signatures, and abstract
    /// methods, etc. That is, any non-concrete implementation.
    pub fn is_ts_empty_body_function(&self) -> bool {
        match self {
            Self::PropertyDefinition(_)
            | Self::StaticBlock(_)
            | Self::AccessorProperty(_)
            | Self::TSIndexSignature(_) => false,
            Self::MethodDefinition(method) => method.value.body.is_none(),
        }
    }

    /// Returns `true` if this class element uses any TypeScript syntax such as index signatures (like `[key: string]: any`),
    /// abstract properties, function overload signatures, or `declare`.
    pub fn is_typescript_syntax(&self) -> bool {
        match self {
            Self::TSIndexSignature(_) => true,
            Self::MethodDefinition(method) => method.value.is_typescript_syntax(),
            Self::PropertyDefinition(property) => {
                property.r#type == PropertyDefinitionType::TSAbstractPropertyDefinition
            }
            Self::AccessorProperty(property) => property.r#type.is_abstract(),
            Self::StaticBlock(_) => false,
        }
    }

    /// `true` for [decorated](Decorator) class elements.
    pub fn has_decorator(&self) -> bool {
        match self {
            Self::MethodDefinition(method) => !method.decorators.is_empty(),
            Self::PropertyDefinition(property) => !property.decorators.is_empty(),
            Self::AccessorProperty(property) => !property.decorators.is_empty(),
            Self::StaticBlock(_) | Self::TSIndexSignature(_) => false,
        }
    }

    /// Has this property been marked as abstract?
    ///
    /// ```ts
    /// abstract class Foo {    // <-- not considered
    ///   foo: string;          // <-- false
    ///   abstract bar: string; // <-- true
    /// }
    /// ```
    pub fn is_abstract(&self) -> bool {
        match self {
            Self::MethodDefinition(method) => method.r#type.is_abstract(),
            Self::AccessorProperty(accessor) => accessor.r#type.is_abstract(),
            Self::PropertyDefinition(property) => property.r#type.is_abstract(),
            Self::StaticBlock(_) | Self::TSIndexSignature(_) => false,
        }
    }
}

impl PropertyDefinitionType {
    /// `true` for abstract properties and methods.
    pub fn is_abstract(self) -> bool {
        self == Self::TSAbstractPropertyDefinition
    }
}

impl MethodDefinitionKind {
    /// `true` for constructors.
    pub fn is_constructor(self) -> bool {
        self == Self::Constructor
    }

    /// `true` for regular methods.
    pub fn is_method(self) -> bool {
        self == Self::Method
    }

    /// `true` for setter methods.
    pub fn is_set(self) -> bool {
        self == Self::Set
    }

    /// `true` for getter methods.
    pub fn is_get(self) -> bool {
        self == Self::Get
    }

    /// Returns `true` if this method is a getter or a setter.
    ///
    /// Analogous to [`PropertyKind::is_accessor`].
    pub fn is_accessor(self) -> bool {
        matches!(self, Self::Get | Self::Set)
    }

    /// Returns the [`ScopeFlags`] for this method definition kind.
    pub fn scope_flags(self) -> ScopeFlags {
        match self {
            Self::Constructor => ScopeFlags::Constructor | ScopeFlags::Function,
            Self::Method => ScopeFlags::Function,
            Self::Get => ScopeFlags::GetAccessor | ScopeFlags::Function,
            Self::Set => ScopeFlags::SetAccessor | ScopeFlags::Function,
        }
    }
}

impl MethodDefinitionType {
    /// Returns `true` if this method definition is a TypeScript `abstract` method.
    ///
    /// See: [`MethodDefinitionType::TSAbstractMethodDefinition`]
    pub fn is_abstract(self) -> bool {
        self == Self::TSAbstractMethodDefinition
    }
}

impl<'a> ModuleDeclaration<'a> {
    /// Returns `true` if this module declaration uses any TypeScript syntax such as the `type` or `declare` keywords.
    pub fn is_typescript_syntax(&self) -> bool {
        match self {
            ModuleDeclaration::ImportDeclaration(_) => false,
            ModuleDeclaration::ExportDefaultDeclaration(decl) => decl.is_typescript_syntax(),
            ModuleDeclaration::ExportNamedDeclaration(decl) => decl.is_typescript_syntax(),
            ModuleDeclaration::ExportAllDeclaration(decl) => decl.is_typescript_syntax(),
            ModuleDeclaration::TSNamespaceExportDeclaration(_)
            | ModuleDeclaration::TSExportAssignment(_) => true,
        }
    }

    /// Returns `true` if this is an [import declaration](`ModuleDeclaration::ImportDeclaration`).
    pub fn is_import(&self) -> bool {
        matches!(self, Self::ImportDeclaration(_))
    }

    /// Returns `true` if this is an export declaration.
    pub fn is_export(&self) -> bool {
        matches!(
            self,
            Self::ExportAllDeclaration(_)
                | Self::ExportDefaultDeclaration(_)
                | Self::ExportNamedDeclaration(_)
                | Self::TSExportAssignment(_)
                | Self::TSNamespaceExportDeclaration(_)
        )
    }

    /// Returns `true`` if this is a default export declaration.
    pub fn is_default_export(&self) -> bool {
        matches!(self, Self::ExportDefaultDeclaration(_))
    }

    /// Returns the import/export source of this module declaration, if it has one.
    ///
    /// ## Example
    ///
    /// - `import foo from "foo/thing"` => `"foo/thing"`
    /// - `export * from "foo"` => `"foo"`
    /// - `export default foo` => `None`
    pub fn source(&self) -> Option<&StringLiteral<'a>> {
        match self {
            Self::ImportDeclaration(decl) => Some(&decl.source),
            Self::ExportAllDeclaration(decl) => Some(&decl.source),
            Self::ExportNamedDeclaration(decl) => decl.source.as_ref(),
            Self::ExportDefaultDeclaration(_)
            | Self::TSExportAssignment(_)
            | Self::TSNamespaceExportDeclaration(_) => None,
        }
    }

    /// Returns the with clause of an import/export declaration, if it has one.
    ///
    /// ## Example
    ///
    /// - `import thing from "lib" with { key: "data" }` => `Some(WithClause)`
    /// - `export * from "lib" with { key: "data" }` => `Some(WithClause)`
    /// - `export default thing` => `None`
    pub fn with_clause(&self) -> Option<&WithClause<'a>> {
        match self {
            Self::ImportDeclaration(decl) => decl.with_clause.as_deref(),
            Self::ExportAllDeclaration(decl) => decl.with_clause.as_deref(),
            Self::ExportNamedDeclaration(decl) => decl.with_clause.as_deref(),
            Self::ExportDefaultDeclaration(_)
            | Self::TSExportAssignment(_)
            | Self::TSNamespaceExportDeclaration(_) => None,
        }
    }
}

impl AccessorPropertyType {
    /// Returns `true` if this accessor property is a TypeScript `abstract` accessor.
    ///
    /// See: [`AccessorPropertyType::TSAbstractAccessorProperty`]
    pub fn is_abstract(self) -> bool {
        self == Self::TSAbstractAccessorProperty
    }
}

impl<'a> ImportDeclarationSpecifier<'a> {
    /// Returns the bound local identifier of this import declaration specifier.
    pub fn local(&self) -> &BindingIdentifier<'a> {
        match self {
            ImportDeclarationSpecifier::ImportSpecifier(specifier) => &specifier.local,
            ImportDeclarationSpecifier::ImportNamespaceSpecifier(specifier) => &specifier.local,
            ImportDeclarationSpecifier::ImportDefaultSpecifier(specifier) => &specifier.local,
        }
    }

    /// Returns the name of the bound local identifier for this import declaration specifier.
    ///
    /// ## Example
    ///
    /// - `import { foo } from "lib"` => `"foo"`
    /// - `import * as foo from "lib"` => `"foo"`
    /// - `import foo from "lib"` => `"foo"`
    pub fn name(&self) -> Cow<'a, str> {
        Cow::Borrowed(self.local().name.as_str())
    }
}

impl<'a> ImportAttributeKey<'a> {
    /// Returns the string value of this import attribute key.
    pub fn as_atom(&self) -> Atom<'a> {
        match self {
            Self::Identifier(identifier) => identifier.name,
            Self::StringLiteral(literal) => literal.value,
        }
    }
}

impl ExportNamedDeclaration<'_> {
    /// Returns `true` if this export declaration uses any TypeScript syntax (such as `type` or `declare`).
    pub fn is_typescript_syntax(&self) -> bool {
        self.export_kind == ImportOrExportKind::Type
            || self.declaration.as_ref().is_some_and(Declaration::is_typescript_syntax)
    }
}

impl ExportDefaultDeclaration<'_> {
    /// Returns `true` if this export declaration uses any TypeScript syntax (such as `declare` or `interface`).
    pub fn is_typescript_syntax(&self) -> bool {
        self.declaration.is_typescript_syntax()
    }
}

impl ExportAllDeclaration<'_> {
    /// Returns `true` if is a TypeScript type-only export (`import type` or `export type`).
    pub fn is_typescript_syntax(&self) -> bool {
        self.export_kind.is_type()
    }
}

impl ExportDefaultDeclarationKind<'_> {
    /// Returns `true` if this export declaration uses any TypeScript syntax (such as `declare` or `interface`).
    #[inline]
    pub fn is_typescript_syntax(&self) -> bool {
        match self {
            Self::FunctionDeclaration(func) => func.is_typescript_syntax(),
            Self::ClassDeclaration(class) => class.is_typescript_syntax(),
            Self::TSInterfaceDeclaration(_) => true,
            _ => false,
        }
    }
}

impl Display for ModuleExportName<'_> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Self::IdentifierName(identifier) => identifier.name.fmt(f),
            Self::IdentifierReference(identifier) => identifier.name.fmt(f),
            Self::StringLiteral(literal) => write!(f, r#""{}""#, literal.value),
        }
    }
}

impl<'a> ModuleExportName<'a> {
    /// Returns the exported name of this module export name.
    ///
    /// ## Example
    ///
    /// - `export { foo }` => `"foo"`
    /// - `export { foo as bar }` => `"bar"`
    /// - `export { foo as "anything" }` => `"anything"`
    pub fn name(&self) -> Atom<'a> {
        match self {
            Self::IdentifierName(identifier) => identifier.name,
            Self::IdentifierReference(identifier) => identifier.name,
            Self::StringLiteral(literal) => literal.value,
        }
    }

    /// Returns the exported identifier name of this module export name.
    ///
    /// ## Example
    ///
    /// - `export { foo }` => `Some("foo")`
    /// - `export { foo as bar }` => `Some("bar")`
    /// - `export { foo as "anything" }` => `None`
    pub fn identifier_name(&self) -> Option<Atom<'a>> {
        match self {
            Self::IdentifierName(identifier) => Some(identifier.name),
            Self::IdentifierReference(identifier) => Some(identifier.name),
            Self::StringLiteral(_) => None,
        }
    }

    /// Returns `true` if this module export name is an identifier, and not a string literal.
    ///
    /// ## Example
    ///
    /// - `export { foo }` => `true`
    /// - `export { "foo" }` => `false`
    pub fn is_identifier(&self) -> bool {
        matches!(self, Self::IdentifierName(_) | Self::IdentifierReference(_))
    }
}

impl ImportPhase {
    /// Returns the syntax associated with this [`ImportPhase`].
    ///
    /// ## Example
    ///
    /// - [`Source`][`ImportPhase::Source`] => `"source"`
    /// - [`Defer`][`ImportPhase::Defer`] => `"defer"`
    pub fn as_str(self) -> &'static str {
        match self {
            Self::Source => "source",
            Self::Defer => "defer",
        }
    }
}