Rollup merge of #52658 - Wallacoloo:topics/use-option-methods, r=cramertj

Prefer `Option::map`/etc over `match` wherever it improves clarity

This isn't intended to change behavior anywhere. A lot of times statements like `match x { None => None, Some(y) => [...] }` can be rewritten using `Option::map` or `Option::and_then` in a way that preserves or improves clarity, so that's what I've done here.

I think it's particularly valuable to keep things in `libcore` and `libstd` pretty/idiomatic since it's not uncommon to follow the `[src]` links when browsing the rust-lang.org docs for std/core. If there's any concern about pushing style-based changes though, I'll happily back out the non-std/core commits here.

1 files changed, 4 insertions, 8 deletions

diff --git a/src/libsyntax_ext/deriving/generic/ty.rs b/src/libsyntax_ext/deriving/generic/ty.rs
index dcccb187bef..a0845e0982d 100644
--- a/src/libsyntax_ext/deriving/generic/ty.rs
+++ b/src/libsyntax_ext/deriving/generic/ty.rs
@@ -138,17 +138,13 @@ pub fn nil_ty<'r>() -> Ty<'r> {
 }
 
 fn mk_lifetime(cx: &ExtCtxt, span: Span, lt: &Option<&str>) -> Option<ast::Lifetime> {
-    match *lt {
-        Some(s) => Some(cx.lifetime(span, Ident::from_str(s))),
-        None => None,
-    }
+    lt.map(|s|
+        cx.lifetime(span, Ident::from_str(s))
+    )
 }
 
 fn mk_lifetimes(cx: &ExtCtxt, span: Span, lt: &Option<&str>) -> Vec<ast::Lifetime> {
-    match *lt {
-        Some(s) => vec![cx.lifetime(span, Ident::from_str(s))],
-        None => vec![],
-    }
+    mk_lifetime(cx, span, lt).into_iter().collect()
 }
 
 impl<'a> Ty<'a> {