1 files changed, 125 insertions, 0 deletions
diff --git a/third_party/rust/wasm-encoder/src/component/exports.rs b/third_party/rust/wasm-encoder/src/component/exports.rs
new file mode 100644
index 0000000000..9720d51b02
--- /dev/null
+++ b/third_party/rust/wasm-encoder/src/component/exports.rs
@@ -0,0 +1,125 @@
+use super::{
+    COMPONENT_SORT, CORE_MODULE_SORT, CORE_SORT, FUNCTION_SORT, INSTANCE_SORT, TYPE_SORT,
+    VALUE_SORT,
+};
+use crate::{encode_section, ComponentSection, ComponentSectionId, ComponentTypeRef, Encode};
+
+/// Represents the kind of an export from a WebAssembly component.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum ComponentExportKind {
+    /// The export is a core module.
+    Module,
+    /// The export is a function.
+    Func,
+    /// The export is a value.
+    Value,
+    /// The export is a type.
+    Type,
+    /// The export is an instance.
+    Instance,
+    /// The export is a component.
+    Component,
+}
+
+impl Encode for ComponentExportKind {
+    fn encode(&self, sink: &mut Vec<u8>) {
+        match self {
+            Self::Module => {
+                sink.push(CORE_SORT);
+                sink.push(CORE_MODULE_SORT);
+            }
+            Self::Func => {
+                sink.push(FUNCTION_SORT);
+            }
+            Self::Value => {
+                sink.push(VALUE_SORT);
+            }
+            Self::Type => {
+                sink.push(TYPE_SORT);
+            }
+            Self::Instance => {
+                sink.push(INSTANCE_SORT);
+            }
+            Self::Component => {
+                sink.push(COMPONENT_SORT);
+            }
+        }
+    }
+}
+
+/// An encoder for the export section of WebAssembly component.
+///
+/// # Example
+///
+/// ```rust
+/// use wasm_encoder::{Component, ComponentExportSection, ComponentExportKind};
+///
+/// // This exports a function named "foo"
+/// let mut exports = ComponentExportSection::new();
+/// exports.export("foo", "", ComponentExportKind::Func, 0, None);
+///
+/// let mut component = Component::new();
+/// component.section(&exports);
+///
+/// let bytes = component.finish();
+/// ```
+#[derive(Clone, Debug, Default)]
+pub struct ComponentExportSection {
+    bytes: Vec<u8>,
+    num_added: u32,
+}
+
+impl ComponentExportSection {
+    /// Create a new component export section encoder.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// The number of exports in the section.
+    pub fn len(&self) -> u32 {
+        self.num_added
+    }
+
+    /// Determines if the section is empty.
+    pub fn is_empty(&self) -> bool {
+        self.num_added == 0
+    }
+
+    /// Define an export in the export section.
+    pub fn export(
+        &mut self,
+        name: &str,
+        url: &str,
+        kind: ComponentExportKind,
+        index: u32,
+        ty: Option<ComponentTypeRef>,
+    ) -> &mut Self {
+        name.encode(&mut self.bytes);
+        url.encode(&mut self.bytes);
+        kind.encode(&mut self.bytes);
+        index.encode(&mut self.bytes);
+        match ty {
+            Some(ty) => {
+                self.bytes.push(0x01);
+                ty.encode(&mut self.bytes);
+            }
+            None => {
+                self.bytes.push(0x00);
+            }
+        }
+        self.num_added += 1;
+        self
+    }
+}
+
+impl Encode for ComponentExportSection {
+    fn encode(&self, sink: &mut Vec<u8>) {
+        encode_section(sink, self.num_added, &self.bytes);
+    }
+}
+
+impl ComponentSection for ComponentExportSection {
+    fn id(&self) -> u8 {
+        ComponentSectionId::Export.into()
+    }
+}