range.adapter: Add container-range adapters. Fix #67

source/tanya/range/adapter.d

@@ -28,24 +28,67 @@ version (unittest)
     }
 }
 
-package (tanya) auto backInserter(Container)(return ref Container container)
-if (hasMember!(Container, "insertBack"))
+private mixin template InserterCtor()
 {
-    static struct BackInserter
-    {
     private Container* container;
 
     this(ref Container container) @trusted
     {
         this.container = &container;
     }
+}
 
+/**
+ * If $(D_PARAM container) is a container with `insertBack`-support,
+ * $(D_PSYMBOL backInserter) returns an output range that puts the elements
+ * into the container with `insertBack`.
+ *
+ * The resulting output range supports all types `insertBack` supports.
+ *
+ * The range keeps a reference to the container passed to it, it doesn't use
+ * any other storage. So there is no method to get the written data out of the
+ * range - the container passed to $(D_PSYMBOL backInserter) contains that data
+ * and can be used directly after all operations on the output range are
+ * completed. It also means that the result range is not allowed to outlive its
+ * container.
+ *
+ * Params:
+ *  Container = Container type.
+ *  container = Container used as an output range.
+ *
+ * Returns: `insertBack`-based output range.
+ */
+auto backInserter(Container)(return scope ref Container container)
+if (hasMember!(Container, "insertBack"))
+{
+    static struct Inserter
+    {
         void opCall(T)(auto ref T data)
         {
             this.container.insertBack(forward!data);
         }
+
+        mixin InserterCtor;
     }
-    return BackInserter(container);
+    return Inserter(container);
+}
+
+///
+@nogc nothrow pure @safe unittest
+{
+    static struct Container
+    {
+        int element;
+
+        void insertBack(int element)
+        {
+            this.element = element;
+        }
+    }
+    Container container;
+    backInserter(container)(5);
+
+    assert(container.element == 5);
 }
 
 @nogc nothrow pure @safe unittest
@@ -63,3 +106,56 @@ if (hasMember!(Container, "insertBack"))
     Container container;
     static assert(isOutputRange!(typeof(backInserter(container)), string));
 }
+
+/**
+ * If $(D_PARAM container) is a container with `insertFront`-support,
+ * $(D_PSYMBOL frontInserter) returns an output range that puts the elements
+ * into the container with `insertFront`.
+ *
+ * The resulting output range supports all types `insertFront` supports.
+ *
+ * The range keeps a reference to the container passed to it, it doesn't use
+ * any other storage. So there is no method to get the written data out of the
+ * range - the container passed to $(D_PSYMBOL frontInserter) contains that data
+ * and can be used directly after all operations on the output range are
+ * completed. It also means that the result range is not allowed to outlive its
+ * container.
+ *
+ * Params:
+ *  Container = Container type.
+ *  container = Container used as an output range.
+ *
+ * Returns: `insertFront`-based output range.
+ */
+auto frontInserter(Container)(return scope ref Container container)
+if (hasMember!(Container, "insertFront"))
+{
+    static struct Inserter
+    {
+        void opCall(T)(auto ref T data)
+        {
+            this.container.insertFront(forward!data);
+        }
+
+        mixin InserterCtor;
+    }
+    return Inserter(container);
+}
+
+///
+@nogc nothrow pure @safe unittest
+{
+    static struct Container
+    {
+        int element;
+
+        void insertFront(int element)
+        {
+            this.element = element;
+        }
+    }
+    Container container;
+    frontInserter(container)(5);
+
+    assert(container.element == 5);
+}