fix: path-related bugs

crates/erg_common/config.rs

@@ -13,6 +13,7 @@ use std::str::FromStr;
 use crate::help_messages::{command_message, mode_message, OPTIONS};
 use crate::levenshtein::get_similar_name;
 use crate::normalize_path;
+use crate::pathutil::add_postfix_foreach;
 use crate::python_util::{detect_magic_number, get_python_version, PythonVersion};
 use crate::random::random;
 use crate::serialize::{get_magic_num_from_bytes, get_ver_from_magic_num};
@@ -342,39 +343,51 @@ impl Input {
     }
 
     pub fn local_resolve(&self, path: &Path) -> Result<PathBuf, std::io::Error> {
-        let mut dir = if let Self::File(mut path) = self.clone() {
-            path.pop();
-            path
+        let mut dir = if let Self::File(mut file_path) = self.clone() {
+            file_path.pop();
+            file_path
         } else {
             PathBuf::new()
         };
         dir.push(path);
-        dir.set_extension("er");
+        dir.set_extension("er"); // {path}.er
+        let path = dir.canonicalize().or_else(|_| {
+            dir.pop();
+            dir.push(path);
+            dir.push("__init__.er"); // -> {path}/__init__.er
+            dir.canonicalize()
+        })?;
+        Ok(normalize_path(path))
+    }
+
+    pub fn local_decl_resolve(&self, path: &Path) -> Result<PathBuf, std::io::Error> {
+        let mut dir = if let Self::File(mut file_path) = self.clone() {
+            file_path.pop();
+            file_path
+        } else {
+            PathBuf::new()
+        };
+        let path = add_postfix_foreach(path, ".d");
+        let mut comps = path.components();
+        let last = comps.next_back().unwrap();
+        let last_path = Path::new(&last);
+        dir.push(comps);
+        dir.push(last_path);
+        dir.set_extension("d.er"); // {path}.d.er
         let path = dir
             .canonicalize()
             .or_else(|_| {
-                dir.pop();
-                dir.push(path);
-                dir.push("__init__.er"); // {path}/__init__.er
+                dir.pop(); // {path}.d.er -> ./
+                dir.push(last_path); // -> {path}.d
+                dir.push("__init__.d.er"); // -> {path}.d/__init__.d.er
                 dir.canonicalize()
             })
             .or_else(|_| {
-                dir.pop(); // {path}
-                dir.set_extension("d.er");
-                dir.canonicalize()
-            })
-            .or_else(|_| {
-                dir.pop(); // {path}.d.er
-                dir.push(format!("{}.d", path.display())); // {path}.d
-                dir.push("__init__.d.er"); // {path}.d/__init__.d.er
-                dir.canonicalize()
-            })
-            .or_else(|_| {
-                dir.pop(); // {path}.d
-                dir.pop();
+                dir.pop(); // -> {path}.d
+                dir.pop(); // -> ./
                 dir.push("__pycache__");
-                dir.push(path);
-                dir.set_extension("d.er"); // __pycache__/{path}.d.er
+                dir.push(last_path);
+                dir.set_extension("d.er"); // -> __pycache__/{path}.d.er
                 dir.canonicalize()
             })?;
         Ok(normalize_path(path))

crates/erg_common/env.rs

@@ -62,6 +62,6 @@ pub fn erg_pystd_path() -> PathBuf {
     ERG_PYSTD_PATH.with(|s| s.clone())
 }
 
-pub fn erg_external_lib_path() -> PathBuf {
+pub fn erg_py_external_lib_path() -> PathBuf {
     ERG_EXTERNAL_LIB_PATH.with(|s| s.clone())
 }

crates/erg_common/lib.rs

@@ -20,6 +20,7 @@ pub mod opcode;
 pub mod opcode308;
 pub mod opcode310;
 pub mod opcode311;
+pub mod pathutil;
 pub mod python_util;
 pub mod random;
 pub mod serialize;

crates/erg_common/pathutil.rs

@@ -0,0 +1,94 @@
+use std::path::{Component, Path, PathBuf};
+
+pub fn is_cur_dir<P: AsRef<Path>>(path: P) -> bool {
+    path.as_ref()
+        .components()
+        .next()
+        .map_or(false, |c| c == Component::CurDir)
+}
+
+/// ```
+/// # use std::path::{PathBuf};
+/// # use erg_common::pathutil::add_postfix_foreach;
+/// let path = PathBuf::from("erg");
+/// let path = add_postfix_foreach(path, ".d");
+/// assert_eq!(path, PathBuf::from("erg.d"));
+/// let path = PathBuf::from("erg/foo/bar");
+/// let path = add_postfix_foreach(path, ".d");
+/// assert_eq!(path, PathBuf::from("erg.d/foo.d/bar.d"));
+/// ```
+pub fn add_postfix_foreach<P: AsRef<Path>, Q: AsRef<Path>>(path: P, postfix: Q) -> PathBuf {
+    let mut result = PathBuf::new();
+    for c in path.as_ref().components() {
+        match c {
+            Component::Prefix(_) => result.push(c),
+            Component::RootDir => result.push(c),
+            Component::CurDir => result.push(c),
+            Component::ParentDir => result.push(c),
+            Component::Normal(os_str) => {
+                let mut os_string = os_str.to_os_string();
+                os_string.push(postfix.as_ref().as_os_str());
+                result.push(PathBuf::from(os_string));
+            }
+        }
+    }
+    result
+}
+
+pub fn remove_postfix_foreach<P: AsRef<Path>>(path: P, extension: &str) -> PathBuf {
+    let mut result = PathBuf::new();
+    for c in path.as_ref().components() {
+        match c {
+            Component::Prefix(_) => result.push(c),
+            Component::RootDir => result.push(c),
+            Component::CurDir => result.push(c),
+            Component::ParentDir => result.push(c),
+            Component::Normal(os_str) => {
+                let string = os_str.to_string_lossy();
+                result.push(string.trim_end_matches(extension));
+            }
+        }
+    }
+    result
+}
+
+/// cutout the extension from the path, and let file name be the directory name.
+/// ```
+/// # use std::path::{PathBuf};
+/// # use erg_common::pathutil::remove_postfix;
+/// let path = PathBuf::from("erg.d.er");
+/// let path = remove_postfix(path, ".er");
+/// assert_eq!(path, PathBuf::from("erg.d"));
+pub fn remove_postfix<P: AsRef<Path>>(path: P, extension: &str) -> PathBuf {
+    let string = path.as_ref().to_string_lossy();
+    PathBuf::from(string.trim_end_matches(extension))
+}
+
+///
+/// ```
+/// # use std::path::{PathBuf};
+/// # use erg_common::pathutil::squash;
+/// let path = PathBuf::from("erg/../foo");
+/// let path = squash(path);
+/// assert_eq!(path, PathBuf::from("foo"));
+/// let path = PathBuf::from("erg/./foo");
+/// let path = squash(path);
+/// assert_eq!(path, PathBuf::from("erg/foo"));
+/// ```
+pub fn squash(path: PathBuf) -> PathBuf {
+    let mut result = PathBuf::new();
+    for c in path.components() {
+        match c {
+            Component::Prefix(_) => result.push(c),
+            Component::RootDir => result.push(c),
+            Component::CurDir => {}
+            Component::ParentDir => {
+                result.pop();
+            }
+            Component::Normal(os_str) => {
+                result.push(os_str);
+            }
+        }
+    }
+    result
+}

crates/erg_common/str.rs

@@ -117,6 +117,16 @@ impl From<&Str> for Str {
     }
 }
 
+impl From<Cow<'_, str>> for Str {
+    #[inline]
+    fn from(s: Cow<'_, str>) -> Self {
+        match s {
+            Cow::Borrowed(s) => Str::rc(s),
+            Cow::Owned(s) => Str::Rc(s.into()),
+        }
+    }
+}
+
 impl Deref for Str {
     type Target = str;
     fn deref(&self) -> &Self::Target {
@@ -189,6 +199,14 @@ impl Str {
         ret
     }
 
+    pub fn multi_replace(&self, paths: &[(&str, &str)]) -> Self {
+        let mut self_ = self.to_string();
+        for (from, to) in paths {
+            self_ = self_.replace(from, to);
+        }
+        Str::rc(&self_)
+    }
+
     pub fn is_snake_case(&self) -> bool {
         self.chars().all(|c| !c.is_uppercase())
     }

crates/erg_compiler/context/inquire.rs

@@ -3,9 +3,10 @@ use std::option::Option; // conflicting to Type::Option
 use std::path::{Path, PathBuf};
 
 use erg_common::config::{ErgConfig, Input};
-use erg_common::env::{erg_pystd_path, erg_std_path};
+use erg_common::env::{erg_py_external_lib_path, erg_pystd_path, erg_std_path};
 use erg_common::error::{ErrorCore, ErrorKind, Location, SubMessage};
 use erg_common::levenshtein::get_similar_name;
+use erg_common::pathutil::add_postfix_foreach;
 use erg_common::set::Set;
 use erg_common::traits::{Locational, NoTypeDisplay, Stream};
 use erg_common::vis::Visibility;
@@ -2106,15 +2107,30 @@ impl Context {
     }
 
     pub(crate) fn resolve_decl_path(cfg: &ErgConfig, path: &Path) -> Option<PathBuf> {
-        if let Ok(path) = cfg.input.local_resolve(path) {
+        if let Ok(path) = cfg.input.local_decl_resolve(path) {
             Some(path)
-        } else if let Ok(path) = erg_pystd_path()
-            .join(format!("{}.d.er", path.display()))
-            .canonicalize()
-        {
+        } else {
+            let py_roots = [erg_pystd_path, erg_py_external_lib_path];
+            for root in py_roots {
+                if let Some(path) = Self::resolve_std_decl_path(root(), path) {
+                    return Some(path);
+                }
+            }
+            None
+        }
+    }
+
+    pub(crate) fn resolve_std_decl_path(root: PathBuf, path: &Path) -> Option<PathBuf> {
+        let mut path = add_postfix_foreach(path, ".d");
+        path.set_extension("d.er"); // set_extension overrides the previous one
+        if let Ok(path) = root.join(&path).canonicalize() {
             Some(normalize_path(path))
-        } else if let Ok(path) = erg_pystd_path()
-            .join(format!("{}.d", path.display()))
+        // d.er -> .d
+        } else if let Ok(path) = root
+            .join({
+                path.set_extension("");
+                path
+            })
             .join("__init__.d.er")
             .canonicalize()
         {

crates/erg_compiler/link.rs

@@ -2,6 +2,7 @@ use std::mem;
 use std::path::{Path, PathBuf};
 
 use erg_common::config::{ErgConfig, Input};
+use erg_common::pathutil::squash;
 use erg_common::python_util::BUILTIN_PYTHON_MODS;
 use erg_common::traits::Locational;
 use erg_common::Str;
@@ -383,6 +384,7 @@ impl<'a> Linker<'a> {
             &mod_name_str
         };
         dir.push(mod_name_str);
+        let dir = squash(dir);
         let mut comps = dir.components();
         let _first = comps.next().unwrap();
         let path = dir.to_string_lossy().replace(['/', '\\'], ".");