From 4ec599aae571ac8cb3f17432c46cb8e3775e798c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?kleines=20Filmr=C3=B6llchen?= <filmroellchen@serenityos.org>
Date: Fri, 18 Feb 2022 16:39:48 +0100
Subject: [PATCH] AK: Make DisjointChunks support FixedArray

This extracts the shatter_chunk logic, because it needs to be different
for FixedArray.
---
 AK/DisjointChunks.h | 56 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 44 insertions(+), 12 deletions(-)

diff --git a/AK/DisjointChunks.h b/AK/DisjointChunks.h
index 625b97554c..e991ba8c83 100644
--- a/AK/DisjointChunks.h
+++ b/AK/DisjointChunks.h
@@ -11,6 +11,7 @@
 #include <AK/Forward.h>
 #include <AK/Span.h>
 #include <AK/StdLibExtras.h>
+#include <AK/Try.h>
 
 namespace AK {
 
@@ -185,6 +186,48 @@ private:
     Vector<Span<T>> m_spans;
 };
 
+namespace Detail {
+
+template<typename T, typename ChunkType>
+ChunkType shatter_chunk(ChunkType& source_chunk, size_t start, size_t sliced_length)
+{
+    auto wanted_slice = source_chunk.span().slice(start, sliced_length);
+
+    ChunkType new_chunk;
+    if constexpr (IsTriviallyConstructible<T>) {
+        new_chunk.resize(wanted_slice.size());
+
+        TypedTransfer<T>::move(new_chunk.data(), wanted_slice.data(), wanted_slice.size());
+    } else {
+        new_chunk.ensure_capacity(wanted_slice.size());
+        for (auto& entry : wanted_slice)
+            new_chunk.unchecked_append(move(entry));
+    }
+    source_chunk.remove(start, sliced_length);
+    return new_chunk;
+}
+
+template<typename T>
+FixedArray<T> shatter_chunk(FixedArray<T>& source_chunk, size_t start, size_t sliced_length)
+{
+    auto wanted_slice = source_chunk.span().slice(start, sliced_length);
+
+    FixedArray<T> new_chunk = FixedArray<T>::must_create_but_fixme_should_propagate_errors(wanted_slice.size());
+    if constexpr (IsTriviallyConstructible<T>) {
+        TypedTransfer<T>::move(new_chunk.data(), wanted_slice.data(), wanted_slice.size());
+    } else {
+        // FIXME: propagate errors
+        auto copied_chunk = MUST(FixedArray<T>::try_create(wanted_slice));
+        new_chunk.swap(copied_chunk);
+    }
+    // FIXME: propagate errors
+    auto rest_of_chunk = MUST(FixedArray<T>::try_create(source_chunk.span().slice(start)));
+    source_chunk.swap(rest_of_chunk);
+    return new_chunk;
+}
+
+}
+
 template<typename T, typename ChunkType = Vector<T>>
 class DisjointChunks {
 public:
@@ -309,20 +352,9 @@ public:
                 result.m_chunks.append(move(chunk));
             } else {
                 // Shatter the chunk, we were asked for only a part of it :(
-                auto wanted_slice = chunk.span().slice(start, sliced_length);
+                auto new_chunk = Detail::shatter_chunk<T>(chunk, start, sliced_length);
 
-                ChunkType new_chunk;
-                if constexpr (IsTriviallyConstructible<T>) {
-                    new_chunk.resize(wanted_slice.size());
-                    TypedTransfer<T>::move(new_chunk.data(), wanted_slice.data(), wanted_slice.size());
-                } else {
-                    new_chunk.ensure_capacity(wanted_slice.size());
-                    for (auto& entry : wanted_slice)
-                        new_chunk.unchecked_append(move(entry));
-                }
                 result.m_chunks.append(move(new_chunk));
-
-                chunk.remove(start, sliced_length);
             }
             start = 0;
             length -= sliced_length;