refactor: loop-unrolled recursive function SExp::parts as it's called a lot, also fixed it returning [Nil] if passed Nil

1 files changed, 16 insertions, 9 deletions

diff --git a/src/sexp/util.rs b/src/sexp/util.rs
index 1da9ccf..9b8e5dd 100644
--- a/src/sexp/util.rs
+++ b/src/sexp/util.rs
@@ -66,15 +66,22 @@ impl SExp {
     }
 
     pub fn parts(self) -> Vec<SExp> {
-        match self {
-            Atom(x) => vec![Atom(x)],
-            SCons(a, b) if *b == Atom(Nil) => vec![*a],
-            SCons(a, b) => {
-                let mut res = vec![*a];
-                res.extend_from_slice(&(*b).parts());
-                res
-            },
-        }
+	let mut res = vec![];
+	let mut se = self;
+	loop {
+	    match se {
+		Atom(Nil) => break,
+		Atom(x) => {
+		    res.push(Atom(x));
+		    break;
+		},
+		SCons(a, b) => {
+		    res.push(*a);
+		    se = *b;
+		}
+	    }
+	}
+	res
     }
 
     pub fn check_let(self) -> Option<(String, SExp)> {