From 1e46109e50d9b283eaead24aa13fb5216f18866d Mon Sep 17 00:00:00 2001
From: Eugen Wissner <belka@caraus.de>
Date: Mon, 29 Oct 2018 11:14:33 +0100
Subject: [PATCH] algorithm.mutation.destroyAll: New

Fix #71.
---
 source/tanya/algorithm/mutation.d | 46 +++++++++++++++++++++++++++++++
 source/tanya/container/array.d    | 20 ++++----------
 source/tanya/memory/package.d     |  8 +-----
 3 files changed, 53 insertions(+), 21 deletions(-)

diff --git a/source/tanya/algorithm/mutation.d b/source/tanya/algorithm/mutation.d
index 49539d1..99ba239 100644
--- a/source/tanya/algorithm/mutation.d
+++ b/source/tanya/algorithm/mutation.d
@@ -561,3 +561,49 @@ if (isInputRange!Range && hasLvalueElements!Range)
     NonCopyable[] nonCopyable;
     initializeAll(nonCopyable);
 }
+
+/**
+ * Destroys all elements in the $(D_PARAM range).
+ *
+ * This function has effect only if the element type of $(D_PARAM Range) has
+ * an elaborate destructor, i.e. it is a $(D_PSYMBOL struct) with an explicit
+ * or generated by the compiler destructor.
+ *
+ * Params:
+ *  Range = Input range type.
+ *  range = Input range.
+ */
+void destroyAll(Range)(Range range)
+if (isInputRange!Range && hasLvalueElements!Range)
+{
+    static if (hasElaborateDestructor!(ElementType!Range))
+    {
+        foreach (ref e; range)
+        {
+            destroy(e);
+        }
+    }
+}
+
+///
+@nogc nothrow pure @trusted unittest
+{
+    static struct WithDtor
+    {
+        private size_t* counter;
+        ~this() @nogc nothrow pure
+        {
+            if (this.counter !is null)
+            {
+                ++(*this.counter);
+            }
+        }
+    }
+
+    size_t counter;
+    WithDtor[2] withDtor = [WithDtor(&counter), WithDtor(&counter)];
+
+    destroyAll(withDtor[]);
+
+    assert(counter == 2);
+}
diff --git a/source/tanya/container/array.d b/source/tanya/container/array.d
index 57ea482..e0556dd 100644
--- a/source/tanya/container/array.d
+++ b/source/tanya/container/array.d
@@ -414,27 +414,19 @@ struct Array(T)
      */
     @property void length(size_t len) @trusted
     {
-        if (len == length)
-        {
-            return;
-        }
-        else if (len > length)
+        if (len > length)
         {
             reserve(len);
             initializeAll(this.data[length_ .. len]);
         }
         else
         {
-            static if (hasElaborateDestructor!T)
-            {
-                const T* end = this.data + length_ - 1;
-                for (T* e = this.data + len; e != end; ++e)
-                {
-                    destroy(*e);
-                }
-            }
+            destroyAll(this.data[len .. this.length_]);
+        }
+        if (len != length)
+        {
+            length_ = len;
         }
-        length_ = len;
     }
 
     ///
diff --git a/source/tanya/memory/package.d b/source/tanya/memory/package.d
index f0a1c0d..77dc388 100644
--- a/source/tanya/memory/package.d
+++ b/source/tanya/memory/package.d
@@ -341,13 +341,7 @@ if (isPolymorphicType!T)
 
 package(tanya) void[] finalize(T)(ref T[] p)
 {
-    static if (hasElaborateDestructor!(typeof(p[0])))
-    {
-        foreach (ref e; p)
-        {
-            destroy(e);
-        }
-    }
+    destroyAll(p);
     return p;
 }