feat(solc): relative remappings (#786)

ethers-solc/src/remappings.rs

@@ -190,6 +190,124 @@ impl Remapping {
     }
 }
 
+/// A relative [`Remapping`] that's aware of the current location
+///
+/// See [`RelativeRemappingPathBuf`]
+#[derive(Clone, Debug, PartialEq)]
+pub struct RelativeRemapping {
+    pub name: String,
+    pub path: RelativeRemappingPathBuf,
+}
+
+impl RelativeRemapping {
+    /// Creates a new `RelativeRemapping` starting prefixed with `root`
+    pub fn new(remapping: Remapping, root: impl AsRef<Path>) -> Self {
+        Self {
+            name: remapping.name,
+            path: RelativeRemappingPathBuf::with_root(root, remapping.path),
+        }
+    }
+
+    /// Converts this relative remapping into an absolute remapping
+    ///
+    /// This sets to root of the remapping to the given `root` path
+    pub fn to_remapping(mut self, root: PathBuf) -> Remapping {
+        self.path.parent = Some(root);
+        self.into()
+    }
+}
+
+// Remappings are printed as `prefix=target`
+impl fmt::Display for RelativeRemapping {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}={}", self.name, self.path.original().display())
+    }
+}
+
+impl From<RelativeRemapping> for Remapping {
+    fn from(r: RelativeRemapping) -> Self {
+        Remapping { name: r.name, path: r.path.relative().to_string_lossy().to_string() }
+    }
+}
+
+impl From<Remapping> for RelativeRemapping {
+    fn from(r: Remapping) -> Self {
+        Self { name: r.name, path: r.path.into() }
+    }
+}
+
+/// The path part of the [`Remapping`] that knows the path of the file it was configured in, if any.
+///
+/// A [`Remapping`] is intended to be absolute, but paths in configuration files are often desired
+/// to be relative to the configuration file itself. For example, a path of
+/// `weird-erc20/=lib/weird-erc20/src/` configured in a file `/var/foundry.toml` might be desired to
+/// resolve as a `weird-erc20/=/var/lib/weird-erc20/src/` remapping.
+#[derive(Debug, Clone, PartialEq)]
+pub struct RelativeRemappingPathBuf {
+    parent: Option<PathBuf>,
+    path: PathBuf,
+}
+
+impl RelativeRemappingPathBuf {
+    /// Creates a new `RelativeRemappingPathBuf` that checks if the `path` is a child path of
+    /// `parent`.
+    pub fn with_root(parent: impl AsRef<Path>, path: impl AsRef<Path>) -> Self {
+        let parent = parent.as_ref();
+        let path = path.as_ref();
+        if let Ok(path) = path.strip_prefix(parent) {
+            Self { parent: Some(parent.to_path_buf()), path: path.to_path_buf() }
+        } else if path.has_root() {
+            Self { parent: None, path: path.to_path_buf() }
+        } else {
+            Self { parent: Some(parent.to_path_buf()), path: path.to_path_buf() }
+        }
+    }
+
+    /// Returns the path as it was declared, without modification.
+    pub fn original(&self) -> &Path {
+        &self.path
+    }
+
+    /// Returns this path relative to the file it was delcared in, if any.
+    /// Returns the original if this path was not declared in a file or if the
+    /// path has a root.
+    pub fn relative(&self) -> PathBuf {
+        if self.original().has_root() {
+            return self.original().into()
+        }
+        self.parent
+            .as_ref()
+            .map(|p| p.join(self.original()))
+            .unwrap_or_else(|| self.original().into())
+    }
+}
+
+impl<P: AsRef<Path>> From<P> for RelativeRemappingPathBuf {
+    fn from(path: P) -> RelativeRemappingPathBuf {
+        Self { parent: None, path: path.as_ref().to_path_buf() }
+    }
+}
+
+impl Serialize for RelativeRemapping {
+    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
+    where
+        S: serde::ser::Serializer,
+    {
+        serializer.serialize_str(&self.to_string())
+    }
+}
+
+impl<'de> Deserialize<'de> for RelativeRemapping {
+    fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
+    where
+        D: serde::de::Deserializer<'de>,
+    {
+        let remapping = String::deserialize(deserializer)?;
+        let remapping = Remapping::from_str(&remapping).map_err(serde::de::Error::custom)?;
+        Ok(RelativeRemapping { name: remapping.name, path: remapping.path.into() })
+    }
+}
+
 #[derive(Debug, Clone)]
 struct Candidate {
     /// dir that opened the window
@@ -358,6 +476,27 @@ mod tests {
     use super::*;
     use crate::utils::tempdir;
 
+    #[test]
+    fn relative_remapping() {
+        let remapping = "oz=a/b/c/d";
+        let remapping = Remapping::from_str(remapping).unwrap();
+
+        let relative = RelativeRemapping::new(remapping.clone(), "a/b/c");
+        assert_eq!(relative.path.relative(), Path::new(&remapping.path));
+        assert_eq!(relative.path.original(), Path::new("d"));
+
+        let relative = RelativeRemapping::new(remapping.clone(), "x/y");
+        assert_eq!(relative.path.relative(), Path::new("x/y/a/b/c/d"));
+        assert_eq!(relative.path.original(), Path::new(&remapping.path));
+
+        let remapping = "oz=/a/b/c/d";
+        let remapping = Remapping::from_str(remapping).unwrap();
+        let relative = RelativeRemapping::new(remapping.clone(), "a/b");
+        assert_eq!(relative.path.relative(), Path::new(&remapping.path));
+        assert_eq!(relative.path.original(), Path::new(&remapping.path));
+        assert!(relative.path.parent.is_none());
+    }
+
     #[test]
     fn serde() {
         let remapping = "oz=../b/c/d";