Add fn signature query

1 files changed, 59 insertions, 1 deletions

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,