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arrow_function.rs
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arrow_function.rs
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//! Arrow function parsing.
//!
//! More information:
//! - [MDN documentation][mdn]
//! - [ECMAScript specification][spec]
//!
//! [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions
//! [spec]: https://tc39.es/ecma262/#sec-arrow-function-definitions
use super::AssignmentExpression;
use crate::syntax::lexer::TokenKind;
use crate::{
syntax::{
ast::{
node::{ArrowFunctionDecl, FormalParameter, Node, Return, StatementList},
Punctuator,
},
parser::{
error::{ErrorContext, ParseError, ParseResult},
function::{FormalParameters, FunctionBody},
statement::BindingIdentifier,
AllowAwait, AllowIn, AllowYield, Cursor, TokenParser,
},
},
BoaProfiler,
};
use std::io::Read;
/// Arrow function parsing.
///
/// More information:
/// - [MDN documentation][mdn]
/// - [ECMAScript specification][spec]
///
/// [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions
/// [spec]: https://tc39.es/ecma262/#prod-ArrowFunction
#[derive(Debug, Clone, Copy)]
pub(in crate::syntax::parser) struct ArrowFunction {
allow_in: AllowIn,
allow_yield: AllowYield,
allow_await: AllowAwait,
}
impl ArrowFunction {
/// Creates a new `ArrowFunction` parser.
pub(in crate::syntax::parser) fn new<I, Y, A>(
allow_in: I,
allow_yield: Y,
allow_await: A,
) -> Self
where
I: Into<AllowIn>,
Y: Into<AllowYield>,
A: Into<AllowAwait>,
{
Self {
allow_in: allow_in.into(),
allow_yield: allow_yield.into(),
allow_await: allow_await.into(),
}
}
}
impl<R> TokenParser<R> for ArrowFunction
where
R: Read,
{
type Output = ArrowFunctionDecl;
fn parse(self, cursor: &mut Cursor<R>) -> Result<Self::Output, ParseError> {
let _timer = BoaProfiler::global().start_event("ArrowFunction", "Parsing");
let next_token = cursor.peek(0)?.ok_or(ParseError::AbruptEnd)?;
let params = if let TokenKind::Punctuator(Punctuator::OpenParen) = &next_token.kind() {
// CoverParenthesizedExpressionAndArrowParameterList
cursor.expect(Punctuator::OpenParen, "arrow function")?;
let params = FormalParameters::new(self.allow_yield, self.allow_await).parse(cursor)?;
cursor.expect(Punctuator::CloseParen, "arrow function")?;
params
} else {
let param = BindingIdentifier::new(self.allow_yield, self.allow_await)
.parse(cursor)
.context("arrow function")?;
Box::new([FormalParameter::new(param, None, false)])
};
cursor.peek_expect_no_lineterminator(0, "arrow function")?;
cursor.expect(TokenKind::Punctuator(Punctuator::Arrow), "arrow function")?;
let body = ConciseBody::new(self.allow_in).parse(cursor)?;
Ok(ArrowFunctionDecl::new(params, body))
}
}
/// <https://tc39.es/ecma262/#prod-ConciseBody>
#[derive(Debug, Clone, Copy)]
struct ConciseBody {
allow_in: AllowIn,
}
impl ConciseBody {
/// Creates a new `ConcideBody` parser.
fn new<I>(allow_in: I) -> Self
where
I: Into<AllowIn>,
{
Self {
allow_in: allow_in.into(),
}
}
}
impl<R> TokenParser<R> for ConciseBody
where
R: Read,
{
type Output = StatementList;
fn parse(self, cursor: &mut Cursor<R>) -> Result<Self::Output, ParseError> {
match cursor.peek(0)?.ok_or(ParseError::AbruptEnd)?.kind() {
TokenKind::Punctuator(Punctuator::OpenBlock) => {
let _ = cursor.next();
let body = FunctionBody::new(false, false).parse(cursor)?;
cursor.expect(Punctuator::CloseBlock, "arrow function")?;
Ok(body)
}
_ => Ok(StatementList::from(vec![Return::new(
ExpressionBody::new(self.allow_in, false).parse(cursor)?,
None,
)
.into()])),
}
}
}
/// <https://tc39.es/ecma262/#prod-ExpressionBody>
#[derive(Debug, Clone, Copy)]
struct ExpressionBody {
allow_in: AllowIn,
allow_await: AllowAwait,
}
impl ExpressionBody {
/// Creates a new `ExpressionBody` parser.
fn new<I, A>(allow_in: I, allow_await: A) -> Self
where
I: Into<AllowIn>,
A: Into<AllowAwait>,
{
Self {
allow_in: allow_in.into(),
allow_await: allow_await.into(),
}
}
}
impl<R> TokenParser<R> for ExpressionBody
where
R: Read,
{
type Output = Node;
fn parse(self, cursor: &mut Cursor<R>) -> ParseResult {
AssignmentExpression::new(self.allow_in, false, self.allow_await).parse(cursor)
}
}