8 files changed, 86 insertions, 7 deletions

diff --git a/crates/ra_analysis/src/db.rs b/crates/ra_analysis/src/db.rs
index 074a7a7f6..1709be5cf 100644
--- a/crates/ra_analysis/src/db.rs
+++ b/crates/ra_analysis/src/db.rs
@@ -108,6 +108,7 @@ salsa::database_storage! {
             fn impls_in_module() for hir::db::ImplsInModuleQuery;
             fn body_hir() for hir::db::BodyHirQuery;
             fn body_syntax_mapping() for hir::db::BodySyntaxMappingQuery;
+            fn fn_signature() for hir::db::FnSignatureQuery;
         }
     }
 }
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index aaf367e08..96a3c60b9 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -7,7 +7,7 @@ use crate::{
     DefLoc, DefId, MacroCallLoc, MacroCallId, Name, HirFileId,
     SourceFileItems, SourceItemId,
     query_definitions,
-    FnScopes,
+    FnSignature, FnScopes,
     macros::MacroExpansion,
     module::{ModuleId, ModuleTree, ModuleSource,
     nameres::{ItemMap, InputModuleItems}},
@@ -103,6 +103,11 @@ pub trait HirDatabase: SyntaxDatabase
         type BodySyntaxMappingQuery;
         use fn crate::expr::body_syntax_mapping;
     }
+
+    fn fn_signature(def_id: DefId) -> Arc<FnSignature> {
+        type FnSignatureQuery;
+        use fn crate::function::fn_signature;
+    }
 }
 
 }
diff --git a/crates/ra_hir/src/function.rs b/crates/ra_hir/src/function.rs
index 4dbdf81d8..4627be071 100644
--- a/crates/ra_hir/src/function.rs
+++ b/crates/ra_hir/src/function.rs
@@ -11,7 +11,7 @@ use ra_syntax::{
     ast::{self, AstNode, DocCommentsOwner, NameOwner},
 };
 
-use crate::{DefId, DefKind, HirDatabase, ty::InferenceResult, Module, Crate, impl_block::ImplBlock, expr::{Body, BodySyntaxMapping}};
+use crate::{DefId, DefKind, HirDatabase, ty::InferenceResult, Module, Crate, impl_block::ImplBlock, expr::{Body, BodySyntaxMapping}, type_ref::{TypeRef, Mutability}, Name};
 
 pub use self::scope::{FnScopes, ScopesWithSyntaxMapping};
 
@@ -53,6 +53,10 @@ impl Function {
         })
     }
 
+    pub fn signature(&self, db: &impl HirDatabase) -> Arc<FnSignature> {
+        db.fn_signature(self.def_id)
+    }
+
     pub fn signature_info(&self, db: &impl HirDatabase) -> Option<FnSignatureInfo> {
         let syntax = self.syntax(db);
         FnSignatureInfo::new(syntax.borrowed())
@@ -76,6 +80,60 @@ impl Function {
     }
 }
 
+/// The declared signature of a function.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct FnSignature {
+    args: Vec<TypeRef>,
+    ret_type: TypeRef,
+}
+
+impl FnSignature {
+    pub fn args(&self) -> &[TypeRef] {
+        &self.args
+    }
+
+    pub fn ret_type(&self) -> &TypeRef {
+        &self.ret_type
+    }
+}
+
+pub(crate) fn fn_signature(db: &impl HirDatabase, def_id: DefId) -> Arc<FnSignature> {
+    let func = Function::new(def_id);
+    let syntax = func.syntax(db);
+    let node = syntax.borrowed();
+    let mut args = Vec::new();
+    if let Some(param_list) = node.param_list() {
+        if let Some(self_param) = param_list.self_param() {
+            let self_type = if let Some(type_ref) = self_param.type_ref() {
+                TypeRef::from_ast(type_ref)
+            } else {
+                let self_type = TypeRef::Path(Name::self_type().into());
+                match self_param.flavor() {
+                    ast::SelfParamFlavor::Owned => self_type,
+                    ast::SelfParamFlavor::Ref => {
+                        TypeRef::Reference(Box::new(self_type), Mutability::Shared)
+                    }
+                    ast::SelfParamFlavor::MutRef => {
+                        TypeRef::Reference(Box::new(self_type), Mutability::Mut)
+                    }
+                }
+            };
+            args.push(self_type);
+        }
+        for param in param_list.params() {
+            let type_ref = TypeRef::from_ast_opt(param.type_ref());
+            args.push(type_ref);
+        }
+    }
+    let ret_type = if let Some(type_ref) = node.ret_type().and_then(|rt| rt.type_ref()) {
+        TypeRef::from_ast(type_ref)
+    } else {
+        TypeRef::unit()
+    };
+    let sig = FnSignature { args, ret_type };
+    Arc::new(sig)
+}
+
 #[derive(Debug, Clone)]
 pub struct FnSignatureInfo {
     pub name: String,
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 82dc287de..d600b91df 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -47,7 +47,7 @@ pub use self::{
     ids::{HirFileId, DefId, DefLoc, MacroCallId, MacroCallLoc},
     macros::{MacroDef, MacroInput, MacroExpansion},
     module::{Module, ModuleId, Problem, nameres::{ItemMap, PerNs, Namespace}, ModuleScope, Resolution},
-    function::{Function, FnScopes, ScopesWithSyntaxMapping},
+    function::{Function, FnSignature, FnScopes, ScopesWithSyntaxMapping},
     adt::{Struct, Enum},
     ty::Ty,
     impl_block::{ImplBlock, ImplItem},
diff --git a/crates/ra_hir/src/mock.rs b/crates/ra_hir/src/mock.rs
index 661a5a26b..8d176662c 100644
--- a/crates/ra_hir/src/mock.rs
+++ b/crates/ra_hir/src/mock.rs
@@ -210,6 +210,7 @@ salsa::database_storage! {
             fn impls_in_module() for db::ImplsInModuleQuery;
             fn body_hir() for db::BodyHirQuery;
             fn body_syntax_mapping() for db::BodySyntaxMappingQuery;
+            fn fn_signature() for db::FnSignatureQuery;
         }
     }
 }
diff --git a/crates/ra_hir/src/name.rs b/crates/ra_hir/src/name.rs
index 6f95b168f..90229bc54 100644
--- a/crates/ra_hir/src/name.rs
+++ b/crates/ra_hir/src/name.rs
@@ -35,6 +35,10 @@ impl Name {
         Name::new("self".into())
     }
 
+    pub(crate) fn self_type() -> Name {
+        Name::new("Self".into())
+    }
+
     pub(crate) fn tuple_field_name(idx: usize) -> Name {
         Name::new(idx.to_string().into())
     }
diff --git a/crates/ra_hir/src/path.rs b/crates/ra_hir/src/path.rs
index 2e42caffe..dcf4cf8b6 100644
--- a/crates/ra_hir/src/path.rs
+++ b/crates/ra_hir/src/path.rs
@@ -67,10 +67,7 @@ impl Path {
 
     /// Converts an `ast::NameRef` into a single-identifier `Path`.
     pub fn from_name_ref(name_ref: ast::NameRef) -> Path {
-        Path {
-            kind: PathKind::Plain,
-            segments: vec![name_ref.as_name()],
-        }
+        name_ref.as_name().into()
     }
 
     /// `true` is this path is a single identifier, like `foo`
@@ -92,6 +89,15 @@ impl Path {
     }
 }
 
+impl From<Name> for Path {
+    fn from(name: Name) -> Path {
+        Path {
+            kind: PathKind::Plain,
+            segments: vec![name],
+        }
+    }
+}
+
 fn expand_use_tree(
     prefix: Option<Path>,
     tree: ast::UseTree,
diff --git a/crates/ra_hir/src/type_ref.rs b/crates/ra_hir/src/type_ref.rs
index b36bb35d8..859f330c2 100644
--- a/crates/ra_hir/src/type_ref.rs
+++ b/crates/ra_hir/src/type_ref.rs
@@ -107,4 +107,8 @@ impl TypeRef {
             TypeRef::Error
         }
     }
+
+    pub fn unit() -> TypeRef {
+        TypeRef::Tuple(Vec::new())
+    }
 }