1 files changed, 60 insertions, 0 deletions
diff --git a/third_party/rust/wast/src/wat.rs b/third_party/rust/wast/src/wat.rs
new file mode 100644
index 0000000000..631bc3d0ed
--- /dev/null
+++ b/third_party/rust/wast/src/wat.rs
@@ -0,0 +1,60 @@
+use crate::component::Component;
+use crate::core::{Module, ModuleField, ModuleKind};
+use crate::kw;
+use crate::parser::{Parse, Parser, Result};
+use crate::token::Span;
+
+/// A `*.wat` file parser, or a parser for one parenthesized module.
+///
+/// This is the top-level type which you'll frequently parse when working with
+/// this crate. A `*.wat` file is either one `module` s-expression or a sequence
+/// of s-expressions that are module fields.
+#[derive(Debug)]
+#[allow(missing_docs)]
+pub enum Wat<'a> {
+    Module(Module<'a>),
+    Component(Component<'a>),
+}
+
+impl Wat<'_> {
+    fn validate(&self, parser: Parser<'_>) -> Result<()> {
+        match self {
+            Wat::Module(m) => m.validate(parser),
+            Wat::Component(c) => c.validate(parser),
+        }
+    }
+
+    /// Encodes this `Wat` to binary form. This calls either [`Module::encode`]
+    /// or [`Component::encode`].
+    pub fn encode(&mut self) -> std::result::Result<Vec<u8>, crate::Error> {
+        match self {
+            Wat::Module(m) => m.encode(),
+            Wat::Component(c) => c.encode(),
+        }
+    }
+}
+
+impl<'a> Parse<'a> for Wat<'a> {
+    fn parse(parser: Parser<'a>) -> Result<Self> {
+        if !parser.has_meaningful_tokens() {
+            return Err(parser.error("expected at least one module field"));
+        }
+
+        let _r = parser.register_annotation("custom");
+        let wat = if parser.peek2::<kw::module>() {
+            Wat::Module(parser.parens(|parser| parser.parse())?)
+        } else if parser.peek2::<kw::component>() {
+            Wat::Component(parser.parens(|parser| parser.parse())?)
+        } else {
+            let fields = ModuleField::parse_remaining(parser)?;
+            Wat::Module(Module {
+                span: Span { offset: 0 },
+                id: None,
+                name: None,
+                kind: ModuleKind::Text(fields),
+            })
+        };
+        wat.validate(parser)?;
+        Ok(wat)
+    }
+}