feat: concat sourcemap (#423)

README.md

@@ -18,6 +18,7 @@ The Rolldown project are standing upon the shoulders of these giants:
 
 - [rollup](https://github.com/rollup/rollup), created by [Rich-Harris](https://github.com/Rich-Harris) and maintained by [lukastaegert](https://github.com/lukastaegert).
 - [esbuild](https://github.com/evanw/esbuild), created by [evanw](https://github.com/evanw).
+- [parcel_sourcemap](https://github.com/parcel-bundler/source-map).
 
 # Licenses
 

crates/rolldown_sourcemap/src/concat_sourcemap.rs

@@ -0,0 +1,82 @@
+use parcel_sourcemap::SourceMap as ParcelSourcemap;
+
+use crate::SourceMap;
+
+pub fn concat_sourcemaps(
+  content_and_sourcemaps: &[(String, Option<&SourceMap>)],
+) -> Result<(String, SourceMap), String> {
+  let mut s = String::new();
+  let mut map = ParcelSourcemap::new("");
+  let mut line_offset = 0;
+
+  for (index, (content, sourcemap)) in content_and_sourcemaps.iter().enumerate() {
+    s.push_str(content);
+    if index != content_and_sourcemaps.len() - 1 {
+      s.push('\n');
+    }
+
+    if let Some(sourcemap) = sourcemap {
+      map
+        .add_sourcemap(
+          &mut sourcemap.get_inner().cloned().ok_or("concat sourcemap not inner sourcemap")?,
+          line_offset.into(),
+        )
+        .map_err(|e| e.to_string())?;
+    }
+    line_offset += u32::try_from(content.lines().count() + 1).map_err(|e| e.to_string())?;
+  }
+
+  Ok((s, map.into()))
+}
+
+#[cfg(test)]
+mod tests {
+  use parcel_sourcemap::SourceMap;
+  use serde_json;
+  #[test]
+  fn concat_sourcemaps_works() {
+    let map = SourceMap::from_json(
+        "",
+        r#"{
+          "version":3,
+          "sourceRoot":"",
+          "mappings":"AAAA,SAAS,QAAQ,CAAC,IAAY;IAC5B,OAAO,CAAC,GAAG,CAAC,iBAAU,IAAI,CAAE,CAAC,CAAC;AAChC,CAAC",
+          "sources":["index.ts"],
+          "sourcesContent":["function sayHello(name: string) {\n  console.log(`Hello, ${name}`);\n}\n"],
+          "names":[]
+        }"#,
+    )
+    .unwrap().into();
+    let content_and_sourcemaps = vec![
+      ("\nconsole.log()".to_string(), None),
+      (
+        "function sayHello(name: string) {\n  console.log(`Hello, ${name}`);\n}\n".to_string(),
+        Some(&map),
+      ),
+    ];
+
+    let (content, mut map) =
+      super::concat_sourcemaps(&content_and_sourcemaps).expect("should not fail");
+
+    assert_eq!(
+      content,
+      "\nconsole.log()\nfunction sayHello(name: string) {\n  console.log(`Hello, ${name}`);\n}\n"
+    );
+    let expected = r#"{
+      "version": 3,
+      "sources": [
+      "index.ts"
+    ],
+    "sourceRoot": null,
+    "sourcesContent": [
+        "function sayHello(name: string) {\n  console.log(`Hello, ${name}`);\n}\n"
+    ],
+    "names": [],
+    "mappings": ";;;AAAA,SAAS,QAAQ,CAAC,IAAY;IAC5B,OAAO,CAAC,GAAG,CAAC,iBAAU,IAAI,CAAE,CAAC,CAAC;AAChC,CAAC"
+  }"#;
+    assert_eq!(
+      map.to_json().as_str().parse::<serde_json::Value>().unwrap(),
+      expected.parse::<serde_json::Value>().unwrap()
+    );
+  }
+}

crates/rolldown_sourcemap/src/lib.rs

@@ -1,5 +1,7 @@
 use parcel_sourcemap::SourceMap as ParcelSourcemap;
+mod concat_sourcemap;
 
+pub use concat_sourcemap::concat_sourcemaps;
 #[derive(Debug, Default, Clone)]
 pub struct SourceMap {
   pub mappings: String,
@@ -28,6 +30,10 @@ impl SourceMap {
   pub fn to_data_url(&mut self) -> String {
     self.inner.as_mut().expect("should have inner").to_data_url(None).expect("should success")
   }
+
+  pub fn get_inner(&self) -> Option<&ParcelSourcemap> {
+    self.inner.as_ref()
+  }
 }
 
 impl From<ParcelSourcemap> for SourceMap {
@@ -41,16 +47,16 @@ pub fn collapse_sourcemaps(sourcemap_chain: Vec<SourceMap>) -> Result<Option<Sou
     .into_iter()
     .map(|sourcemap| {
       let mut map = ParcelSourcemap::new(sourcemap.source_root.as_deref().unwrap_or(""));
-      if let Err(e) = map.add_vlq_map(
-        sourcemap.mappings.as_bytes(),
-        sourcemap.sources,
-        sourcemap.sources_content,
-        sourcemap.names,
-        0,
-        0,
-      ) {
-        return Err(format!("{e}"));
-      }
+      map
+        .add_vlq_map(
+          sourcemap.mappings.as_bytes(),
+          sourcemap.sources,
+          sourcemap.sources_content,
+          sourcemap.names,
+          0,
+          0,
+        )
+        .map_err(|e| e.to_string())?;
       Ok(map)
     })
     .rev()
@@ -59,9 +65,7 @@ pub fn collapse_sourcemaps(sourcemap_chain: Vec<SourceMap>) -> Result<Option<Sou
   let Some(mut result) = parcel_sourcemap_chain.pop() else { return Ok(None) };
 
   for mut sourcemap in parcel_sourcemap_chain.into_iter().rev() {
-    if let Err(e) = sourcemap.extends(&mut result) {
-      return Err(format!("{e}"));
-    };
+    sourcemap.extends(&mut result).map_err(|e| e.to_string())?;
     result = sourcemap;
   }