add find method to the core::container::Map trait

Author: thestinger

src/libcore/container.rs

@@ -13,6 +13,8 @@
 #[forbid(deprecated_mode)];
 #[forbid(deprecated_pattern)];
 
+use option::Option;
+
 pub trait Container {
     /// Return the number of elements in the container
     pure fn len(&self) -> uint;
@@ -39,6 +41,9 @@ pub trait Map<K, V>: Mutable {
     /// Visit all values
     pure fn each_value(&self, f: fn(&V) -> bool);
 
+    /// Return the value corresponding to the key in the map
+    pure fn find(&self, key: &K) -> Option<&self/V>;
+
     /// Insert a key-value pair into the map. An existing value for a
     /// key is replaced by the new value. Return true if the key did
     /// not already exist in the map.

src/libcore/hashmap.rs

@@ -300,6 +300,26 @@ pub mod linear {
             self.each(|_k, v| blk(v))
         }
 
+        pure fn find(&self, k: &K) -> Option<&self/V> {
+            match self.bucket_for_key(self.buckets, k) {
+                FoundEntry(idx) => {
+                    match self.buckets[idx] {
+                        Some(ref bkt) => {
+                            // FIXME(#3148)---should be inferred
+                            let bkt: &self/Bucket<K,V> = bkt;
+                            Some(&bkt.value)
+                        }
+                        None => {
+                            fail ~"LinearMap::find: internal logic error"
+                        }
+                    }
+                }
+                TableFull | FoundHole(_) => {
+                    None
+                }
+            }
+        }
+
         fn insert(&mut self, k: K, v: V) -> bool {
             if self.size >= self.resize_at {
                 // n.b.: We could also do this after searching, so
@@ -369,26 +389,6 @@ pub mod linear {
             }
         }
 
-        pure fn find(&self, k: &K) -> Option<&self/V> {
-            match self.bucket_for_key(self.buckets, k) {
-                FoundEntry(idx) => {
-                    match self.buckets[idx] {
-                        Some(ref bkt) => {
-                            // FIXME(#3148)---should be inferred
-                            let bkt: &self/Bucket<K,V> = bkt;
-                            Some(&bkt.value)
-                        }
-                        None => {
-                            fail ~"LinearMap::find: internal logic error"
-                        }
-                    }
-                }
-                TableFull | FoundHole(_) => {
-                    None
-                }
-            }
-        }
-
         pure fn get(&self, k: &K) -> &self/V {
             match self.find(k) {
                 Some(v) => v,

src/libstd/treemap.rs

@@ -98,6 +98,26 @@ impl <K: Ord, V> TreeMap<K, V>: Map<K, V> {
     /// Visit all values in order
     pure fn each_value(&self, f: fn(&V) -> bool) { self.each(|_, v| f(v)) }
 
+    /// Return the value corresponding to the key in the map
+    pure fn find(&self, key: &K) -> Option<&self/V> {
+        let mut current: &self/Option<~TreeNode<K, V>> = &self.root;
+        loop {
+            match *current {
+              Some(ref r) => {
+                let r: &self/~TreeNode<K, V> = r; // FIXME: #3148
+                if *key < r.key {
+                    current = &r.left;
+                } else if r.key < *key {
+                    current = &r.right;
+                } else {
+                    return Some(&r.value);
+                }
+              }
+              None => return None
+            }
+        }
+    }
+
     /// Insert a key-value pair into the map. An existing value for a
     /// key is replaced by the new value. Return true if the key did
     /// not already exist in the map.
@@ -136,26 +156,6 @@ impl <K: Ord, V> TreeMap<K, V> {
         self.each_reverse(|_, v| f(v))
     }
 
-    /// Return the value corresponding to the key in the map
-    pure fn find(&self, key: &K) -> Option<&self/V> {
-        let mut current: &self/Option<~TreeNode<K, V>> = &self.root;
-        loop {
-            match *current {
-              Some(ref r) => {
-                let r: &self/~TreeNode<K, V> = r; // FIXME: #3148
-                if *key < r.key {
-                    current = &r.left;
-                } else if r.key < *key {
-                    current = &r.right;
-                } else {
-                    return Some(&r.value);
-                }
-              }
-              None => return None
-            }
-        }
-    }
-
     /// Get a lazy iterator over the key-value pairs in the map.
     /// Requires that it be frozen (immutable).
     pure fn iter(&self) -> TreeMapIterator/&self<K, V> {