feat: Add source_root handling support

src/builder.rs

@@ -23,6 +23,7 @@ pub struct SourceMapBuilder {
     names: Vec<String>,
     tokens: Vec<RawToken>,
     source_map: HashMap<String, u32>,
+    source_root: Option<String>,
     sources: Vec<String>,
     source_contents: Vec<Option<String>>,
 }
@@ -53,19 +54,30 @@ impl SourceMapBuilder {
             names: vec![],
             tokens: vec![],
             source_map: HashMap::new(),
+            source_root: None,
             sources: vec![],
             source_contents: vec![],
         }
     }
 
     /// Sets the file for the sourcemap (optional)
-    pub fn set_file(&mut self, value: Option<&str>) {
-        self.file = value.map(str::to_owned);
+    pub fn set_file<T: Into<String>>(&mut self, value: Option<T>) {
+        self.file = value.map(Into::into);
     }
 
     /// Returns the currently set file.
     pub fn get_file(&self) -> Option<&str> {
-        self.file.as_ref().map(|x| &x[..])
+        self.file.as_deref()
+    }
+
+    /// Sets a new value for the source_root.
+    pub fn set_source_root<T: Into<String>>(&mut self, value: Option<T>) {
+        self.source_root = value.map(Into::into);
+    }
+
+    /// Returns the embedded source_root in case there is one.
+    pub fn get_source_root(&self) -> Option<&str> {
+        self.source_root.as_deref()
     }
 
     /// Registers a new source with the builder and returns the source ID.
@@ -244,6 +256,10 @@ impl SourceMapBuilder {
         } else {
             None
         };
-        SourceMap::new(self.file, self.tokens, self.names, self.sources, contents)
+
+        let mut sm = SourceMap::new(self.file, self.tokens, self.names, self.sources, contents);
+        sm.set_source_root(self.source_root);
+
+        sm
     }
 }

src/decoder.rs

@@ -227,13 +227,10 @@ pub fn decode_regular(rsm: RawSourceMap) -> Result<SourceMap> {
         _ => "<invalid>".into(),
     });
 
-    Ok(SourceMap::new(
-        file,
-        tokens,
-        names,
-        sources,
-        rsm.sources_content,
-    ))
+    let mut sm = SourceMap::new(file, tokens, names, sources, rsm.sources_content);
+    sm.set_source_root(rsm.source_root);
+
+    Ok(sm)
 }
 
 fn decode_index(rsm: RawSourceMap) -> Result<SourceMapIndex> {

src/encoder.rs

@@ -85,8 +85,7 @@ impl Encodable for SourceMap {
             version: Some(3),
             file: self.get_file().map(|x| Value::String(x.to_string())),
             sources: Some(self.sources().map(|x| Some(x.to_string())).collect()),
-            // XXX: consider setting this to common root
-            source_root: None,
+            source_root: self.get_source_root().map(|x| x.to_string()),
             sources_content: if have_contents { Some(contents) } else { None },
             sections: None,
             names: Some(self.names().map(|x| Value::String(x.to_string())).collect()),

src/types.rs

@@ -458,6 +458,7 @@ pub struct SourceMap {
     tokens: Vec<RawToken>,
     index: Vec<(u32, u32, u32)>,
     names: Vec<String>,
+    source_root: Option<String>,
     sources: Vec<String>,
     sources_content: Vec<Option<SourceView<'static>>>,
 }
@@ -494,7 +495,7 @@ impl SourceMap {
     ///
     /// Note that this operation will generate an equivalent sourcemap to the
     /// one that was generated on load however there might be small differences
-    /// in the generated JSON and layout.  For instance `sourceRoot` will not
+    /// in the generated JSON and layout. For instance `sourceRoot` will not
     /// be set as upon parsing of the sourcemap the sources will already be
     /// expanded.
     ///
@@ -561,6 +562,7 @@ impl SourceMap {
             tokens,
             index,
             names,
+            source_root: None,
             sources,
             sources_content: sources_content
                 .unwrap_or_default()
@@ -572,12 +574,22 @@ impl SourceMap {
 
     /// Returns the embedded filename in case there is one.
     pub fn get_file(&self) -> Option<&str> {
-        self.file.as_ref().map(|x| &x[..])
+        self.file.as_deref()
     }
 
     /// Sets a new value for the file.
-    pub fn set_file(&mut self, value: Option<&str>) {
-        self.file = value.map(str::to_owned);
+    pub fn set_file<T: Into<String>>(&mut self, value: Option<T>) {
+        self.file = value.map(Into::into);
+    }
+
+    /// Returns the embedded source_root in case there is one.
+    pub fn get_source_root(&self) -> Option<&str> {
+        self.source_root.as_deref()
+    }
+
+    /// Sets a new value for the source_root.
+    pub fn set_source_root<T: Into<String>>(&mut self, value: Option<T>) {
+        self.source_root = value.map(Into::into);
     }
 
     /// Looks up a token by its index.

tests/test_builder.rs

@@ -0,0 +1,19 @@
+use sourcemap::SourceMapBuilder;
+
+#[test]
+fn test_builder_into_sourcemap() {
+    let mut builder = SourceMapBuilder::new(None);
+    builder.set_source_root(Some("/foo/bar"));
+    builder.add_source("baz.js");
+    builder.add_name("x");
+
+    let sm = builder.into_sourcemap();
+    assert_eq!(sm.get_source_root(), Some("/foo/bar"));
+    assert_eq!(sm.get_source(0), Some("baz.js"));
+    assert_eq!(sm.get_name(0), Some("x"));
+
+    let expected = b"{\"version\":3,\"sources\":[\"baz.js\"],\"sourceRoot\":\"/foo/bar\",\"names\":[\"x\"],\"mappings\":\"\"}";
+    let mut output: Vec<u8> = vec![];
+    sm.to_writer(&mut output).unwrap();
+    assert_eq!(output, expected);
+}