Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 96 insertions, 0 deletions

diff --git a/dom/script/ScriptDecoding.h b/dom/script/ScriptDecoding.h
new file mode 100644
index 0000000000..a54d120240
--- /dev/null
+++ b/dom/script/ScriptDecoding.h
@@ -0,0 +1,96 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Script decoding templates for processing byte data as UTF-8 or UTF-16. */
+
+#ifndef mozilla_dom_ScriptDecoding_h
+#define mozilla_dom_ScriptDecoding_h
+
+#include "mozilla/Assertions.h"  // MOZ_ASSERT
+#include "mozilla/CheckedInt.h"  // mozilla::CheckedInt
+#include "mozilla/Encoding.h"    // mozilla::Decoder
+#include "mozilla/Span.h"        // mozilla::Span
+#include "mozilla/Tuple.h"       // mozilla::Tie
+#include "mozilla/UniquePtr.h"   // mozilla::UniquePtr
+#include "mozilla/Unused.h"      // mozilla::Unused
+
+#include <stddef.h>     // size_t
+#include <stdint.h>     // uint8_t, uint32_t
+#include <type_traits>  // std::is_same
+
+namespace mozilla {
+namespace dom {
+
+template <typename Unit>
+struct ScriptDecoding {
+  static_assert(std::is_same<Unit, char16_t>::value ||
+                    std::is_same<Unit, Utf8Unit>::value,
+                "must be either UTF-8 or UTF-16");
+};
+
+template <>
+struct ScriptDecoding<char16_t> {
+  static CheckedInt<size_t> MaxBufferLength(const UniquePtr<Decoder>& aDecoder,
+                                            uint32_t aByteLength) {
+    return aDecoder->MaxUTF16BufferLength(aByteLength);
+  }
+
+  static size_t DecodeInto(const UniquePtr<Decoder>& aDecoder,
+                           const Span<const uint8_t>& aSrc,
+                           Span<char16_t> aDest, bool aEndOfSource) {
+    uint32_t result;
+    size_t read;
+    size_t written;
+    bool hadErrors;
+    Tie(result, read, written, hadErrors) =
+        aDecoder->DecodeToUTF16(aSrc, aDest, aEndOfSource);
+    MOZ_ASSERT(result == kInputEmpty);
+    MOZ_ASSERT(read == aSrc.Length());
+    MOZ_ASSERT(written <= aDest.Length());
+    Unused << hadErrors;
+
+    return written;
+  }
+};
+
+template <>
+struct ScriptDecoding<Utf8Unit> {
+  static CheckedInt<size_t> MaxBufferLength(const UniquePtr<Decoder>& aDecoder,
+                                            uint32_t aByteLength) {
+    return aDecoder->MaxUTF8BufferLength(aByteLength);
+  }
+
+  static size_t DecodeInto(const UniquePtr<Decoder>& aDecoder,
+                           const Span<const uint8_t>& aSrc,
+                           Span<Utf8Unit> aDest, bool aEndOfSource) {
+    uint32_t result;
+    size_t read;
+    size_t written;
+    bool hadErrors;
+    // Until C++ char8_t happens, our decoder APIs deal in |uint8_t| while
+    // |Utf8Unit| internally deals with |char|, so there's inevitable impedance
+    // mismatch between |aDest| as |Utf8Unit| and |AsWritableBytes(aDest)| as
+    // |Span<uint8_t>|.  :-(  The written memory will be interpreted through
+    // |char Utf8Unit::mValue| which is *permissible* because any object's
+    // memory can be interpreted as |char|.  Unfortunately, until
+    // twos-complement is mandated, we have to play fast and loose and *hope*
+    // interpreting memory storing |uint8_t| as |char| will pick up the desired
+    // wrapped-around value.  ¯\_(ツ)_/¯
+    Tie(result, read, written, hadErrors) =
+        aDecoder->DecodeToUTF8(aSrc, AsWritableBytes(aDest), aEndOfSource);
+    MOZ_ASSERT(result == kInputEmpty);
+    MOZ_ASSERT(read == aSrc.Length());
+    MOZ_ASSERT(written <= aDest.Length());
+    Unused << hadErrors;
+
+    return written;
+  }
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif  // mozilla_dom_ScriptDecoding_h