1 files changed, 73 insertions, 8 deletions

diff --git a/crates/ra_hir/src/docs.rs b/crates/ra_hir/src/docs.rs
index 5db72c08a..1b0f84de5 100644
--- a/crates/ra_hir/src/docs.rs
+++ b/crates/ra_hir/src/docs.rs
@@ -1,24 +1,60 @@
+use std::sync::Arc;
+
 use ra_syntax::ast;
 
-use crate::HirDatabase;
+use crate::{
+    HirDatabase, DefDatabase, AstDatabase,
+    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)]
-pub struct Documentation(String);
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Documentation(Arc<str>);
 
 impl Documentation {
-    pub fn new(s: &str) -> Self {
-        Self(s.into())
+    fn new(s: &str) -> Documentation {
+        Documentation(s.into())
     }
 
-    pub fn contents(&self) -> &str {
-        &self.0
+    pub fn as_str(&self) -> &str {
+        &*self.0
     }
 }
 
 impl Into<String> for Documentation {
     fn into(self) -> String {
-        self.contents().into()
+        self.as_str().to_owned()
     }
 }
 
@@ -29,3 +65,32 @@ pub trait Docs {
 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)?.1),
+        DocDef::StructField(it) => match it.source(db).1 {
+            FieldSource::Named(named) => docs_from_ast(&*named),
+            FieldSource::Pos(..) => return None,
+        },
+        DocDef::Struct(it) => docs_from_ast(&*it.source(db).1),
+        DocDef::Enum(it) => docs_from_ast(&*it.source(db).1),
+        DocDef::EnumVariant(it) => docs_from_ast(&*it.source(db).1),
+        DocDef::Static(it) => docs_from_ast(&*it.source(db).1),
+        DocDef::Const(it) => docs_from_ast(&*it.source(db).1),
+        DocDef::Function(it) => docs_from_ast(&*it.source(db).1),
+        DocDef::Union(it) => docs_from_ast(&*it.source(db).1),
+        DocDef::Trait(it) => docs_from_ast(&*it.source(db).1),
+        DocDef::TypeAlias(it) => docs_from_ast(&*it.source(db).1),
+        DocDef::MacroDef(it) => docs_from_ast(&*it.source(db).1),
+    }
+}
+
+impl<T: Into<DocDef> + Copy> Docs for T {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        db.documentation((*self).into())
+    }
+}