2 files changed, 206 insertions, 0 deletions

diff --git a/crates/ra_hir/src/code_model/docs.rs b/crates/ra_hir/src/code_model/docs.rs
new file mode 100644
index 000000000..da2b9b854
--- /dev/null
+++ b/crates/ra_hir/src/code_model/docs.rs
@@ -0,0 +1,96 @@
+use std::sync::Arc;
+
+use ra_syntax::ast;
+
+use crate::{
+    HirDatabase, DefDatabase, AstDatabase, HasSource,
+    Module, StructField, Struct, Enum, EnumVariant, Static, Const, Function, Union, Trait, TypeAlias, FieldSource, MacroDef,
+};
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum DocDef {
+    Module(Module),
+    StructField(StructField),
+    Struct(Struct),
+    Enum(Enum),
+    EnumVariant(EnumVariant),
+    Static(Static),
+    Const(Const),
+    Function(Function),
+    Union(Union),
+    Trait(Trait),
+    TypeAlias(TypeAlias),
+    MacroDef(MacroDef),
+}
+
+impl_froms!(
+    DocDef: Module,
+    StructField,
+    Struct,
+    Enum,
+    EnumVariant,
+    Static,
+    Const,
+    Function,
+    Union,
+    Trait,
+    TypeAlias,
+    MacroDef
+);
+
+/// Holds documentation
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Documentation(Arc<str>);
+
+impl Documentation {
+    fn new(s: &str) -> Documentation {
+        Documentation(s.into())
+    }
+
+    pub fn as_str(&self) -> &str {
+        &*self.0
+    }
+}
+
+impl Into<String> for Documentation {
+    fn into(self) -> String {
+        self.as_str().to_owned()
+    }
+}
+
+pub trait Docs {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation>;
+}
+
+pub(crate) fn docs_from_ast(node: &impl ast::DocCommentsOwner) -> Option<Documentation> {
+    node.doc_comment_text().map(|it| Documentation::new(&it))
+}
+
+pub(crate) fn documentation_query(
+    db: &(impl DefDatabase + AstDatabase),
+    def: DocDef,
+) -> Option<Documentation> {
+    match def {
+        DocDef::Module(it) => docs_from_ast(&*it.declaration_source(db)?.ast),
+        DocDef::StructField(it) => match it.source(db).ast {
+            FieldSource::Named(named) => docs_from_ast(&*named),
+            FieldSource::Pos(..) => return None,
+        },
+        DocDef::Struct(it) => docs_from_ast(&*it.source(db).ast),
+        DocDef::Enum(it) => docs_from_ast(&*it.source(db).ast),
+        DocDef::EnumVariant(it) => docs_from_ast(&*it.source(db).ast),
+        DocDef::Static(it) => docs_from_ast(&*it.source(db).ast),
+        DocDef::Const(it) => docs_from_ast(&*it.source(db).ast),
+        DocDef::Function(it) => docs_from_ast(&*it.source(db).ast),
+        DocDef::Union(it) => docs_from_ast(&*it.source(db).ast),
+        DocDef::Trait(it) => docs_from_ast(&*it.source(db).ast),
+        DocDef::TypeAlias(it) => docs_from_ast(&*it.source(db).ast),
+        DocDef::MacroDef(it) => docs_from_ast(&*it.source(db).ast),
+    }
+}
+
+impl<T: Into<DocDef> + Copy> Docs for T {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        db.documentation((*self).into())
+    }
+}
diff --git a/crates/ra_hir/src/code_model/src.rs b/crates/ra_hir/src/code_model/src.rs
new file mode 100644
index 000000000..5785d3b26
--- /dev/null
+++ b/crates/ra_hir/src/code_model/src.rs
@@ -0,0 +1,110 @@
+use ra_syntax::{TreeArc, ast};
+
+use crate::{
+    HirFileId, DefDatabase, AstDatabase, Module, ModuleSource,
+    StructField, Struct, Enum, Union, EnumVariant, Function, Static, Trait, Const, TypeAlias,
+    FieldSource, MacroDef, ids::AstItemDef,
+};
+
+pub struct Source<T> {
+    pub file_id: HirFileId,
+    pub ast: T,
+}
+
+pub trait HasSource {
+    type Ast;
+    fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<Self::Ast>;
+}
+
+/// NB: Module is !HasSource, because it has two source nodes at the same time:
+/// definition and declaration.
+impl Module {
+    /// Returns a node which defines this module. That is, a file or a `mod foo {}` with items.
+    pub fn definition_source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<ModuleSource> {
+        let def_map = db.crate_def_map(self.krate);
+        let decl_id = def_map[self.module_id].declaration;
+        let file_id = def_map[self.module_id].definition;
+        let ast = ModuleSource::new(db, file_id, decl_id);
+        let file_id = file_id.map(HirFileId::from).unwrap_or_else(|| decl_id.unwrap().file_id());
+        Source { file_id, ast }
+    }
+
+    /// Returns a node which declares this module, either a `mod foo;` or a `mod foo {}`.
+    /// `None` for the crate root.
+    pub fn declaration_source(
+        self,
+        db: &(impl DefDatabase + AstDatabase),
+    ) -> Option<Source<TreeArc<ast::Module>>> {
+        let def_map = db.crate_def_map(self.krate);
+        let decl = def_map[self.module_id].declaration?;
+        let ast = decl.to_node(db);
+        Some(Source { file_id: decl.file_id(), ast })
+    }
+}
+
+impl HasSource for StructField {
+    type Ast = FieldSource;
+    fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<FieldSource> {
+        self.source_impl(db)
+    }
+}
+impl HasSource for Struct {
+    type Ast = TreeArc<ast::StructDef>;
+    fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<TreeArc<ast::StructDef>> {
+        self.id.source(db)
+    }
+}
+impl HasSource for Union {
+    type Ast = TreeArc<ast::StructDef>;
+    fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<TreeArc<ast::StructDef>> {
+        self.id.source(db)
+    }
+}
+impl HasSource for Enum {
+    type Ast = TreeArc<ast::EnumDef>;
+    fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<TreeArc<ast::EnumDef>> {
+        self.id.source(db)
+    }
+}
+impl HasSource for EnumVariant {
+    type Ast = TreeArc<ast::EnumVariant>;
+    fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<TreeArc<ast::EnumVariant>> {
+        self.source_impl(db)
+    }
+}
+impl HasSource for Function {
+    type Ast = TreeArc<ast::FnDef>;
+    fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<TreeArc<ast::FnDef>> {
+        self.id.source(db)
+    }
+}
+impl HasSource for Const {
+    type Ast = TreeArc<ast::ConstDef>;
+    fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<TreeArc<ast::ConstDef>> {
+        self.id.source(db)
+    }
+}
+impl HasSource for Static {
+    type Ast = TreeArc<ast::StaticDef>;
+    fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<TreeArc<ast::StaticDef>> {
+        self.id.source(db)
+    }
+}
+impl HasSource for Trait {
+    type Ast = TreeArc<ast::TraitDef>;
+    fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<TreeArc<ast::TraitDef>> {
+        self.id.source(db)
+    }
+}
+impl HasSource for TypeAlias {
+    type Ast = TreeArc<ast::TypeAliasDef>;
+    fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<TreeArc<ast::TypeAliasDef>> {
+        self.id.source(db)
+    }
+}
+impl HasSource for MacroDef {
+    type Ast = TreeArc<ast::MacroCall>;
+    fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<TreeArc<ast::MacroCall>> {
+        Source { file_id: self.id.0.file_id(), ast: self.id.0.to_node(db) }
+    }
+}