1 files changed, 186 insertions, 0 deletions

diff --git a/crates/ra_hir/src/nameres/mod_resolution.rs b/crates/ra_hir/src/nameres/mod_resolution.rs
new file mode 100644
index 000000000..918c9591f
--- /dev/null
+++ b/crates/ra_hir/src/nameres/mod_resolution.rs
@@ -0,0 +1,186 @@
+//! This module resolves `mod foo;` declaration to file.
+
+use std::{borrow::Cow, sync::Arc};
+
+use ra_db::{FileId, SourceRoot};
+use ra_syntax::SmolStr;
+use relative_path::RelativePathBuf;
+
+use crate::{DefDatabase, HirFileId, Name};
+
+#[derive(Clone, Copy)]
+pub(super) struct ParentModule<'a> {
+    pub(super) name: &'a Name,
+    pub(super) attr_path: Option<&'a SmolStr>,
+}
+
+impl<'a> ParentModule<'a> {
+    fn attribute_path(&self) -> Option<&SmolStr> {
+        self.attr_path.filter(|p| !p.is_empty())
+    }
+}
+
+pub(super) fn resolve_submodule(
+    db: &impl DefDatabase,
+    file_id: HirFileId,
+    name: &Name,
+    is_root: bool,
+    attr_path: Option<&SmolStr>,
+    parent_module: Option<ParentModule<'_>>,
+) -> Result<FileId, RelativePathBuf> {
+    let file_id = file_id.original_file(db);
+    let source_root_id = db.file_source_root(file_id);
+    let path = db.file_relative_path(file_id);
+    let root = RelativePathBuf::default();
+    let dir_path = path.parent().unwrap_or(&root);
+    let mod_name = path.file_stem().unwrap_or("unknown");
+
+    let resolve_mode = match (attr_path.filter(|p| !p.is_empty()), parent_module) {
+        (Some(file_path), Some(parent_module)) => {
+            let file_path = normalize_attribute_path(file_path);
+            match parent_module.attribute_path() {
+                Some(parent_module_attr_path) => {
+                    let path = dir_path
+                        .join(format!(
+                            "{}/{}",
+                            normalize_attribute_path(parent_module_attr_path),
+                            file_path
+                        ))
+                        .normalize();
+                    ResolutionMode::InlineModuleWithAttributePath(
+                        InsideInlineModuleMode::WithAttributePath(path),
+                    )
+                }
+                None => {
+                    let path =
+                        dir_path.join(format!("{}/{}", parent_module.name, file_path)).normalize();
+                    ResolutionMode::InsideInlineModule(InsideInlineModuleMode::WithAttributePath(
+                        path,
+                    ))
+                }
+            }
+        }
+        (None, Some(parent_module)) => match parent_module.attribute_path() {
+            Some(parent_module_attr_path) => {
+                let path = dir_path.join(format!(
+                    "{}/{}.rs",
+                    normalize_attribute_path(parent_module_attr_path),
+                    name
+                ));
+                ResolutionMode::InlineModuleWithAttributePath(InsideInlineModuleMode::File(path))
+            }
+            None => {
+                let path = dir_path.join(format!("{}/{}.rs", parent_module.name, name));
+                ResolutionMode::InsideInlineModule(InsideInlineModuleMode::File(path))
+            }
+        },
+        (Some(file_path), None) => {
+            let file_path = normalize_attribute_path(file_path);
+            let path = dir_path.join(file_path.as_ref()).normalize();
+            ResolutionMode::OutOfLine(OutOfLineMode::WithAttributePath(path))
+        }
+        (None, None) => {
+            let is_dir_owner = is_root || mod_name == "mod";
+            if is_dir_owner {
+                let file_mod = dir_path.join(format!("{}.rs", name));
+                let dir_mod = dir_path.join(format!("{}/mod.rs", name));
+                ResolutionMode::OutOfLine(OutOfLineMode::RootOrModRs {
+                    file: file_mod,
+                    directory: dir_mod,
+                })
+            } else {
+                let path = dir_path.join(format!("{}/{}.rs", mod_name, name));
+                ResolutionMode::OutOfLine(OutOfLineMode::FileInDirectory(path))
+            }
+        }
+    };
+
+    resolve_mode.resolve(db.source_root(source_root_id))
+}
+
+fn normalize_attribute_path(file_path: &SmolStr) -> Cow<str> {
+    let current_dir = "./";
+    let windows_path_separator = r#"\"#;
+    let current_dir_normalize = if file_path.starts_with(current_dir) {
+        &file_path[current_dir.len()..]
+    } else {
+        file_path.as_str()
+    };
+    if current_dir_normalize.contains(windows_path_separator) {
+        Cow::Owned(current_dir_normalize.replace(windows_path_separator, "/"))
+    } else {
+        Cow::Borrowed(current_dir_normalize)
+    }
+}
+
+enum OutOfLineMode {
+    RootOrModRs { file: RelativePathBuf, directory: RelativePathBuf },
+    FileInDirectory(RelativePathBuf),
+    WithAttributePath(RelativePathBuf),
+}
+
+impl OutOfLineMode {
+    pub fn resolve(&self, source_root: Arc<SourceRoot>) -> Result<FileId, RelativePathBuf> {
+        match self {
+            OutOfLineMode::RootOrModRs { file, directory } => {
+                match source_root.file_by_relative_path(file) {
+                    None => resolve_simple_path(source_root, directory).map_err(|_| file.clone()),
+                    file_id => resolve_find_result(file_id, file),
+                }
+            }
+            OutOfLineMode::FileInDirectory(path) => resolve_simple_path(source_root, path),
+            OutOfLineMode::WithAttributePath(path) => resolve_simple_path(source_root, path),
+        }
+    }
+}
+
+enum InsideInlineModuleMode {
+    File(RelativePathBuf),
+    WithAttributePath(RelativePathBuf),
+}
+
+impl InsideInlineModuleMode {
+    pub fn resolve(&self, source_root: Arc<SourceRoot>) -> Result<FileId, RelativePathBuf> {
+        match self {
+            InsideInlineModuleMode::File(path) => resolve_simple_path(source_root, path),
+            InsideInlineModuleMode::WithAttributePath(path) => {
+                resolve_simple_path(source_root, path)
+            }
+        }
+    }
+}
+
+enum ResolutionMode {
+    OutOfLine(OutOfLineMode),
+    InsideInlineModule(InsideInlineModuleMode),
+    InlineModuleWithAttributePath(InsideInlineModuleMode),
+}
+
+impl ResolutionMode {
+    pub fn resolve(&self, source_root: Arc<SourceRoot>) -> Result<FileId, RelativePathBuf> {
+        use self::ResolutionMode::*;
+
+        match self {
+            OutOfLine(mode) => mode.resolve(source_root),
+            InsideInlineModule(mode) => mode.resolve(source_root),
+            InlineModuleWithAttributePath(mode) => mode.resolve(source_root),
+        }
+    }
+}
+
+fn resolve_simple_path(
+    source_root: Arc<SourceRoot>,
+    path: &RelativePathBuf,
+) -> Result<FileId, RelativePathBuf> {
+    resolve_find_result(source_root.file_by_relative_path(path), path)
+}
+
+fn resolve_find_result(
+    file_id: Option<FileId>,
+    path: &RelativePathBuf,
+) -> Result<FileId, RelativePathBuf> {
+    match file_id {
+        Some(file_id) => Ok(file_id.clone()),
+        None => Err(path.clone()),
+    }
+}