add FixedStaticAsset and TextContentSourceAsset (vercel/turborepo#4692)

### Description

needed for metadata support in next.js
(#48823)

Author: sokra

crates/turbopack-ecmascript/src/lib.rs

@@ -17,6 +17,7 @@ mod path_visitor;
 pub(crate) mod references;
 pub mod resolve;
 pub(crate) mod special_cases;
+pub mod text;
 pub(crate) mod transform;
 pub mod tree_shake;
 pub mod typescript;

crates/turbopack-ecmascript/src/text/mod.rs

@@ -0,0 +1,49 @@
+use anyhow::Result;
+use turbo_tasks::primitives::StringVc;
+use turbo_tasks_fs::FileContent;
+use turbopack_core::{
+    asset::{Asset, AssetContentVc, AssetVc},
+    ident::AssetIdentVc,
+};
+
+use crate::utils::StringifyJs;
+
+#[turbo_tasks::function]
+fn modifier() -> StringVc {
+    StringVc::cell("text content".to_string())
+}
+
+/// A source asset that exports the string content of an asset as the default
+/// export of a JS module.
+#[turbo_tasks::value]
+pub struct TextContentSourceAsset {
+    pub source: AssetVc,
+}
+
+#[turbo_tasks::value_impl]
+impl TextContentSourceAssetVc {
+    #[turbo_tasks::function]
+    pub fn new(source: AssetVc) -> Self {
+        TextContentSourceAsset { source }.cell()
+    }
+}
+
+#[turbo_tasks::value_impl]
+impl Asset for TextContentSourceAsset {
+    #[turbo_tasks::function]
+    fn ident(&self) -> AssetIdentVc {
+        self.source.ident().with_modifier(modifier())
+    }
+
+    #[turbo_tasks::function]
+    async fn content(&self) -> Result<AssetContentVc> {
+        let source = self.source.content().file_content();
+        let FileContent::Content(content) = &*source.await? else {
+            return Ok(FileContent::NotFound.cell().into());
+        };
+        let text = content.content().to_str()?;
+        let code = format!("export default {};", StringifyJs(&text));
+        let content = FileContent::Content(code.into()).cell();
+        Ok(content.into())
+    }
+}

crates/turbopack-static/src/fixed.rs

@@ -0,0 +1,39 @@
+use anyhow::Result;
+use turbo_tasks_fs::FileSystemPathVc;
+use turbopack_core::{
+    asset::{Asset, AssetContentVc, AssetVc},
+    ident::AssetIdentVc,
+};
+
+/// A static asset that is served at a fixed output path. It won't use
+/// content hashing to generate a long term cacheable URL.
+#[turbo_tasks::value]
+pub struct FixedStaticAsset {
+    output_path: FileSystemPathVc,
+    source: AssetVc,
+}
+
+#[turbo_tasks::value_impl]
+impl FixedStaticAssetVc {
+    #[turbo_tasks::function]
+    pub fn new(output_path: FileSystemPathVc, source: AssetVc) -> Self {
+        FixedStaticAsset {
+            output_path,
+            source,
+        }
+        .cell()
+    }
+}
+
+#[turbo_tasks::value_impl]
+impl Asset for FixedStaticAsset {
+    #[turbo_tasks::function]
+    async fn ident(&self) -> Result<AssetIdentVc> {
+        Ok(AssetIdentVc::from_path(self.output_path))
+    }
+
+    #[turbo_tasks::function]
+    fn content(&self) -> AssetContentVc {
+        self.source.content()
+    }
+}

crates/turbopack-static/src/lib.rs

@@ -10,6 +10,8 @@
 
 #![feature(min_specialization)]
 
+pub mod fixed;
+
 use anyhow::{anyhow, Result};
 use turbo_tasks::{primitives::StringVc, Value, ValueToString};
 use turbo_tasks_fs::FileContent;