1 files changed, 61 insertions, 0 deletions

diff --git a/crates/ra_hir_def/src/function.rs b/crates/ra_hir_def/src/function.rs
new file mode 100644
index 000000000..33265275e
--- /dev/null
+++ b/crates/ra_hir_def/src/function.rs
@@ -0,0 +1,61 @@
+use std::sync::Arc;
+
+use hir_expand::name::{self, AsName, Name};
+use ra_syntax::ast::{self, NameOwner, TypeAscriptionOwner};
+
+use crate::{
+    db::DefDatabase2,
+    type_ref::{Mutability, TypeRef},
+    FunctionId, HasSource, Lookup,
+};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct FunctionData {
+    pub name: Name,
+    pub params: Vec<TypeRef>,
+    pub ret_type: TypeRef,
+    /// True if the first param is `self`. This is relevant to decide whether this
+    /// can be called as a method.
+    pub has_self_param: bool,
+}
+
+impl FunctionData {
+    pub(crate) fn fn_data_query(db: &impl DefDatabase2, func: FunctionId) -> Arc<FunctionData> {
+        let src = func.lookup(db).source(db);
+        let name = src.value.name().map(|n| n.as_name()).unwrap_or_else(Name::missing);
+        let mut params = Vec::new();
+        let mut has_self_param = false;
+        if let Some(param_list) = src.value.param_list() {
+            if let Some(self_param) = param_list.self_param() {
+                let self_type = if let Some(type_ref) = self_param.ascribed_type() {
+                    TypeRef::from_ast(type_ref)
+                } else {
+                    let self_type = TypeRef::Path(name::SELF_TYPE.into());
+                    match self_param.kind() {
+                        ast::SelfParamKind::Owned => self_type,
+                        ast::SelfParamKind::Ref => {
+                            TypeRef::Reference(Box::new(self_type), Mutability::Shared)
+                        }
+                        ast::SelfParamKind::MutRef => {
+                            TypeRef::Reference(Box::new(self_type), Mutability::Mut)
+                        }
+                    }
+                };
+                params.push(self_type);
+                has_self_param = true;
+            }
+            for param in param_list.params() {
+                let type_ref = TypeRef::from_ast_opt(param.ascribed_type());
+                params.push(type_ref);
+            }
+        }
+        let ret_type = if let Some(type_ref) = src.value.ret_type().and_then(|rt| rt.type_ref()) {
+            TypeRef::from_ast(type_ref)
+        } else {
+            TypeRef::unit()
+        };
+
+        let sig = FunctionData { name, params, ret_type, has_self_param };
+        Arc::new(sig)
+    }
+}