Add Scheme-style `cond!` macro to syntax::ext::expand

Addresses issue #6037

2 files changed, 24 insertions, 28 deletions

diff --git a/src/libstd/fun_treemap.rs b/src/libstd/fun_treemap.rs
index 3bffeddbe09..30edd535a88 100644
--- a/src/libstd/fun_treemap.rs
+++ b/src/libstd/fun_treemap.rs
@@ -33,45 +33,40 @@ enum TreeNode<K, V> {
 pub fn init<K, V>() -> Treemap<K, V> { @Empty }
 
 /// Insert a value into the map
-pub fn insert<K:Copy + Eq + Ord,V:Copy>(m: Treemap<K, V>, k: K, v: V)
-  -> Treemap<K, V> {
+pub fn insert<K:Copy + Eq + Ord,V:Copy>(m: Treemap<K, V>, k: K, v: V) -> Treemap<K, V> {
     @match m {
-       @Empty => Node(@k, @v, @Empty, @Empty),
-       @Node(@copy kk, vv, left, right) => {
-         if k < kk {
-             Node(@kk, vv, insert(left, k, v), right)
-         } else if k == kk {
-             Node(@kk, @v, left, right)
-         } else { Node(@kk, vv, left, insert(right, k, v)) }
-       }
-     }
+        @Empty => Node(@k, @v, @Empty, @Empty),
+        @Node(@copy kk, vv, left, right) => cond!(
+            | k <  kk { Node(@kk, vv, insert(left, k, v), right) }
+            | k == kk { Node(@kk, @v, left, right)               }
+            _         { Node(@kk, vv, left, insert(right, k, v)) }
+        )
+    }
 }
 
 /// Find a value based on the key
 pub fn find<K:Eq + Ord,V:Copy>(m: Treemap<K, V>, k: K) -> Option<V> {
     match *m {
-      Empty => None,
-      Node(@ref kk, @copy v, left, right) => {
-        if k == *kk {
-            Some(v)
-        } else if k < *kk { find(left, k) } else { find(right, k) }
-      }
+        Empty => None,
+        Node(@ref kk, @copy v, left, right) => cond!(
+            | k == *kk { Some(v)        }
+            | k <  *kk { find(left, k)  }
+            _          { find(right, k) }
+        )
     }
 }
 
 /// Visit all pairs in the map in order.
 pub fn traverse<K, V: Copy>(m: Treemap<K, V>, f: &fn(&K, &V)) {
     match *m {
-      Empty => (),
-      /*
-        Previously, this had what looked like redundant
-        matches to me, so I changed it. but that may be a
-        de-optimization -- tjc
-       */
-      Node(@ref k, @ref v, left, right) => {
-        traverse(left, f);
-        f(k, v);
-        traverse(right, f);
-      }
+        Empty => (),
+        // Previously, this had what looked like redundant
+        // matches to me, so I changed it. but that may be a
+        // de-optimization -- tjc
+        Node(@ref k, @ref v, left, right) => {
+            traverse(left, f);
+            f(k, v);
+            traverse(right, f);
+        }
     }
 }
diff --git a/src/libstd/std.rc b/src/libstd/std.rc
index 915aab59a71..d29791449b6 100644
--- a/src/libstd/std.rc
+++ b/src/libstd/std.rc
@@ -63,6 +63,7 @@ pub mod flatpipes;
 
 pub mod bitv;
 pub mod deque;
+#[cfg(not(stage0))]
 pub mod fun_treemap;
 pub mod list;
 pub mod priority_queue;