add if let and while let postfix for Option and Result

Signed-off-by: Benjamin Coenen <5719034+bnjjj@users.noreply.github.com>

Author: bnjjj

crates/ra_assists/src/utils.rs

@@ -103,15 +103,15 @@ fn invert_special_case(expr: &ast::Expr) -> Option<ast::Expr> {
 }
 
 #[derive(Clone, Copy)]
-pub(crate) enum TryEnum {
+pub enum TryEnum {
     Result,
     Option,
 }
 
 impl TryEnum {
     const ALL: [TryEnum; 2] = [TryEnum::Option, TryEnum::Result];
 
-    pub(crate) fn from_ty(sema: &Semantics<RootDatabase>, ty: &Type) -> Option<TryEnum> {
+    pub fn from_ty(sema: &Semantics<RootDatabase>, ty: &Type) -> Option<TryEnum> {
         let enum_ = match ty.as_adt() {
             Some(Adt::Enum(it)) => it,
             _ => return None,

crates/ra_hir/src/code_model.rs

@@ -1086,28 +1086,6 @@ impl Type {
         matches!(self.ty.value, Ty::Apply(ApplicationTy { ctor: TypeCtor::Bool, .. }))
     }
 
-    pub fn is_option(&self, db: &dyn HirDatabase) -> bool {
-        if let Some(adt_ty) = self.as_adt() {
-            if let Adt::Enum(_) = adt_ty {
-                if self.display(db).to_string().starts_with("Option<") {
-                    return true;
-                }
-            }
-        }
-        false
-    }
-
-    pub fn is_result(&self, db: &dyn HirDatabase) -> bool {
-        if let Some(adt_ty) = self.as_adt() {
-            if let Adt::Enum(_) = adt_ty {
-                if self.display(db).to_string().starts_with("Result<") {
-                    return true;
-                }
-            }
-        }
-        false
-    }
-
     pub fn is_mutable_reference(&self) -> bool {
         matches!(
             self.ty.value,

crates/ra_ide/src/completion/complete_postfix.rs

@@ -14,6 +14,7 @@ use crate::{
     },
     CompletionItem,
 };
+use ra_assists::utils::TryEnum;
 
 pub(super) fn complete_postfix(acc: &mut Completions, ctx: &CompletionContext) {
     if !ctx.config.enable_postfix_completions {
@@ -38,46 +39,51 @@ pub(super) fn complete_postfix(acc: &mut Completions, ctx: &CompletionContext) {
         None => return,
     };
 
-    if receiver_ty.is_option(ctx.db) {
-        postfix_snippet(
-            ctx,
-            cap,
-            &dot_receiver,
-            "ifl",
-            "if let Some {}",
-            &format!("if let Some($1) = {} {{\n    $0\n}}", receiver_text),
-        )
-        .add_to(acc);
+    if let Some(try_enum) = TryEnum::from_ty(&ctx.sema, &receiver_ty) {
+        match try_enum {
+            TryEnum::Result => {
+                postfix_snippet(
+                    ctx,
+                    cap,
+                    &dot_receiver,
+                    "ifl",
+                    "if let Ok {}",
+                    &format!("if let Ok($1) = {} {{\n    $0\n}}", receiver_text),
+                )
+                .add_to(acc);
 
-        postfix_snippet(
-            ctx,
-            cap,
-            &dot_receiver,
-            "while",
-            "while let Some {}",
-            &format!("while let Some($1) = {} {{\n    $0\n}}", receiver_text),
-        )
-        .add_to(acc);
-    } else if receiver_ty.is_result(ctx.db) {
-        postfix_snippet(
-            ctx,
-            cap,
-            &dot_receiver,
-            "ifl",
-            "if let Ok {}",
-            &format!("if let Ok($1) = {} {{\n    $0\n}}", receiver_text),
-        )
-        .add_to(acc);
+                postfix_snippet(
+                    ctx,
+                    cap,
+                    &dot_receiver,
+                    "while",
+                    "while let Ok {}",
+                    &format!("while let Ok($1) = {} {{\n    $0\n}}", receiver_text),
+                )
+                .add_to(acc);
+            }
+            TryEnum::Option => {
+                postfix_snippet(
+                    ctx,
+                    cap,
+                    &dot_receiver,
+                    "ifl",
+                    "if let Some {}",
+                    &format!("if let Some($1) = {} {{\n    $0\n}}", receiver_text),
+                )
+                .add_to(acc);
 
-        postfix_snippet(
-            ctx,
-            cap,
-            &dot_receiver,
-            "while",
-            "while let Ok {}",
-            &format!("while let Ok($1) = {} {{\n    $0\n}}", receiver_text),
-        )
-        .add_to(acc);
+                postfix_snippet(
+                    ctx,
+                    cap,
+                    &dot_receiver,
+                    "while",
+                    "while let Some {}",
+                    &format!("while let Some($1) = {} {{\n    $0\n}}", receiver_text),
+                )
+                .add_to(acc);
+            }
+        }
     } else if receiver_ty.is_bool() || receiver_ty.is_unknown() {
         postfix_snippet(
             ctx,