Merge pull request moonbitlang#434 from ZnPdCo/map-as-iter

add Map::as_iter method

Author: bobzhang

map/map.mbti

@@ -1,5 +1,7 @@
 package moonbitlang/core/map
 
+alias @moonbitlang/core/iter as @iter
+
 // Values
 fn empty[K, V]() -> Map[K, V]
 
@@ -8,6 +10,7 @@ fn singleton[K, V](K, V) -> Map[K, V]
 // Types and methods
 type Map
 impl Map {
+  as_iter[K, V](Self[K, V]) -> @iter.Iter[Tuple[K, V]]
   debug_write[K : Debug, V : Debug](Self[K, V], Buffer) -> Unit
   filter[K : Compare + Eq, V](Self[K, V], (V) -> Bool) -> Self[K, V]
   filter_with_key[K : Compare + Eq, V](Self[K, V], (K, V) -> Bool) -> Self[K, V]

map/map_test.mbt

@@ -297,3 +297,23 @@ test "debug_write" {
     "Map::[(0, \"zero\"), (1, \"one\"), (2, \"two\"), (3, \"three\"), (8, \"eight\")]",
   )?
 }
+
+test "as_iter" {
+  let buf = Buffer::make(20)
+  let map = Map::[(1, "one"), (2, "two"), (3, "three")]
+  map.as_iter().iter(
+    fn(e) {
+      let (k, v) = e
+      buf.write_string("[\(k)-\(v)]")
+    },
+  )
+  inspect(buf, content="[1-one][2-two][3-three]")?
+  buf.reset()
+  map.as_iter().take(2).iter(
+    fn(e) {
+      let (k, v) = e
+      buf.write_string("[\(k)-\(v)]")
+    },
+  )
+  inspect(buf, content="[1-one][2-two]")?
+}

map/moon.pkg.json

@@ -3,7 +3,7 @@
     "moonbitlang/core/builtin",
     "moonbitlang/core/assertion",
     "moonbitlang/core/tuple",
-    
+    "moonbitlang/core/iter",
     "moonbitlang/core/string",
     "moonbitlang/core/array",
     "moonbitlang/core/coverage"

map/utils.mbt

@@ -208,3 +208,18 @@ pub fn Map::from_array[K : Compare, V](array : Array[(K, V)]) -> Map[K, V] {
     mp
   }
 }
+
+pub fn as_iter[K, V](self : Map[K, V]) -> @iter.Iter[(K, V)] {
+  @iter.Iter::_unstable_internal_make(
+    fn(yield) {
+      let arr = self.to_array()
+      for i = 0, len = arr.length(); i < len; i = i + 1 {
+        match arr[i] {
+          (key, value) => if yield((key, value)).not() { break false }
+        }
+      } else {
+        true
+      }
+    },
+  )
+}