From c2bf1b3cfbcd157236ed06f381bd8e69078417ef Mon Sep 17 00:00:00 2001
From: Paul Lancaster <paul@lancasterzone.com>
Date: Fri, 9 Oct 2020 23:47:35 +0100
Subject: [PATCH] AsyncFunctionDecl/Expr parser created (not impl)

---
 .../primary/async_function_expression.rs      | 42 +++++++++++++++++
 .../syntax/parser/expression/primary/mod.rs   |  8 +++-
 .../parser/statement/declaration/hoistable.rs | 47 ++++++++++++++++++-
 3 files changed, 94 insertions(+), 3 deletions(-)
 create mode 100644 boa/src/syntax/parser/expression/primary/async_function_expression.rs

diff --git a/boa/src/syntax/parser/expression/primary/async_function_expression.rs b/boa/src/syntax/parser/expression/primary/async_function_expression.rs
new file mode 100644
index 0000000000..61f24e8412
--- /dev/null
+++ b/boa/src/syntax/parser/expression/primary/async_function_expression.rs
@@ -0,0 +1,42 @@
+//! Async Function expression parsing.
+//!
+//! More information:
+//!  - [MDN documentation][mdn]
+//!  - [ECMAScript specification][spec]
+//!
+//! [mdn]:
+//! [spec]:
+
+use crate::{
+    syntax::{
+        ast::node::AsyncFunctionExpr,
+        parser::{Cursor, ParseError, TokenParser},
+    },
+    BoaProfiler,
+};
+
+use std::io::Read;
+
+/// Async Function expression parsing.
+///
+/// More information:
+///  - [MDN documentation][mdn]
+///  - [ECMAScript specification][spec]
+///
+/// [mdn]:
+/// [spec]:
+#[derive(Debug, Clone, Copy)]
+pub(super) struct AsyncFunctionExpression;
+
+impl<R> TokenParser<R> for AsyncFunctionExpression
+where
+    R: Read,
+{
+    type Output = AsyncFunctionExpr;
+
+    fn parse(self, cursor: &mut Cursor<R>) -> Result<Self::Output, ParseError> {
+        let _timer = BoaProfiler::global().start_event("AsyncFunctionExpression", "Parsing");
+
+        unimplemented!("Async function expression parse");
+    }
+}
diff --git a/boa/src/syntax/parser/expression/primary/mod.rs b/boa/src/syntax/parser/expression/primary/mod.rs
index 50cc95cc8a..9963df4b57 100644
--- a/boa/src/syntax/parser/expression/primary/mod.rs
+++ b/boa/src/syntax/parser/expression/primary/mod.rs
@@ -8,14 +8,15 @@
 //! [spec]: https://tc39.es/ecma262/#prod-PrimaryExpression
 
 mod array_initializer;
+mod async_function_expression;
 mod function_expression;
 mod object_initializer;
 #[cfg(test)]
 mod tests;
 
 use self::{
-    array_initializer::ArrayLiteral, function_expression::FunctionExpression,
-    object_initializer::ObjectLiteral,
+    array_initializer::ArrayLiteral, async_function_expression::AsyncFunctionExpression,
+    function_expression::FunctionExpression, object_initializer::ObjectLiteral,
 };
 use super::Expression;
 use crate::{
@@ -77,6 +78,9 @@ where
             TokenKind::Keyword(Keyword::Function) => {
                 FunctionExpression.parse(cursor).map(Node::from)
             }
+            TokenKind::Keyword(Keyword::Async) => {
+                AsyncFunctionExpression.parse(cursor).map(Node::from)
+            }
             TokenKind::Punctuator(Punctuator::OpenParen) => {
                 cursor.set_goal(InputElement::RegExp);
                 let expr =
diff --git a/boa/src/syntax/parser/statement/declaration/hoistable.rs b/boa/src/syntax/parser/statement/declaration/hoistable.rs
index 1f18c09976..a059bbe95d 100644
--- a/boa/src/syntax/parser/statement/declaration/hoistable.rs
+++ b/boa/src/syntax/parser/statement/declaration/hoistable.rs
@@ -7,7 +7,10 @@
 
 use crate::{
     syntax::{
-        ast::{node::FunctionDecl, Keyword, Node, Punctuator},
+        ast::{
+            node::{AsyncFunctionDecl, FunctionDecl},
+            Keyword, Node, Punctuator,
+        },
         parser::{
             function::FormalParameters, function::FunctionBody, statement::BindingIdentifier,
             AllowAwait, AllowDefault, AllowYield, Cursor, ParseError, ParseResult, TokenParser,
@@ -119,3 +122,45 @@ where
         Ok(FunctionDecl::new(name, params, body))
     }
 }
+
+/// Async Function declaration parsing.
+///
+/// More information:
+///  - [MDN documentation][mdn]
+///  - [ECMAScript specification][spec]
+///
+/// [mdn]:
+/// [spec]:
+#[derive(Debug, Clone, Copy)]
+struct AsyncFunctionDeclaration {
+    allow_yield: AllowYield,
+    allow_await: AllowAwait,
+    is_default: AllowDefault,
+}
+
+impl AsyncFunctionDeclaration {
+    /// Creates a new `FunctionDeclaration` parser.
+    fn new<Y, A, D>(allow_yield: Y, allow_await: A, is_default: D) -> Self
+    where
+        Y: Into<AllowYield>,
+        A: Into<AllowAwait>,
+        D: Into<AllowDefault>,
+    {
+        Self {
+            allow_yield: allow_yield.into(),
+            allow_await: allow_await.into(),
+            is_default: is_default.into(),
+        }
+    }
+}
+
+impl<R> TokenParser<R> for AsyncFunctionDeclaration
+where
+    R: Read,
+{
+    type Output = AsyncFunctionDecl;
+
+    fn parse(self, cursor: &mut Cursor<R>) -> Result<Self::Output, ParseError> {
+        unimplemented!("AsyncFunctionDecl parse");
+    }
+}