From 835d49d1534405075d75068635894ead17af56b8 Mon Sep 17 00:00:00 2001
From: Tom Sepez <tsepez@chromium.org>
Date: Wed, 18 Jul 2018 19:28:59 +0000
Subject: Add pdfium::span::as_bytes() and as_writable_bytes().

Picks up some enhancements from base/span.h.  In turn, also adds
the size_bytes() helper.  Differs from base version in that it
works around C++14 enable_if_t<>, and avoids the dynamic_extent
template specialization tricks.

Use it in a few places where appropriate.

Change-Id: I86f72cf0023f2d4317a7afa351fddee601c8f86c
Reviewed-on: https://pdfium-review.googlesource.com/38251
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
---
 third_party/base/span.h | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

(limited to 'third_party')

diff --git a/third_party/base/span.h b/third_party/base/span.h
index 0fb627ba8c..ccffbc1e78 100644
--- a/third_party/base/span.h
+++ b/third_party/base/span.h
@@ -152,10 +152,6 @@ using EnableIfConstSpanCompatibleContainer =
 // Differences from [views.constants]:
 // - no dynamic_extent constant
 //
-// Differences from [span.objectrep]:
-// - no as_bytes()
-// - no as_writeable_bytes()
-//
 // Differences in constants and types:
 // - no element_type type alias
 // - no index_type type alias
@@ -173,7 +169,6 @@ using EnableIfConstSpanCompatibleContainer =
 // - using size_t instead of ptrdiff_t for indexing
 //
 // Differences from [span.obs]:
-// - no size_bytes()
 // - using size_t instead of ptrdiff_t to represent size()
 //
 // Differences from [span.elem]:
@@ -244,6 +239,7 @@ class span {
 
   // [span.obs], span observers
   constexpr size_t size() const noexcept { return size_; }
+  constexpr size_t size_bytes() const noexcept { return size() * sizeof(T); }
   constexpr bool empty() const noexcept { return size_ == 0; }
 
   // [span.elem], span element access
@@ -313,6 +309,18 @@ constexpr bool operator>=(span<T> lhs, span<T> rhs) noexcept {
   return !(lhs < rhs);
 }
 
+// [span.objectrep], views of object representation
+template <typename T>
+span<const uint8_t> as_bytes(span<T> s) noexcept {
+  return {reinterpret_cast<const uint8_t*>(s.data()), s.size_bytes()};
+}
+
+template <typename T,
+          typename U = typename std::enable_if<!std::is_const<T>::value>::type>
+span<uint8_t> as_writable_bytes(span<T> s) noexcept {
+  return {reinterpret_cast<uint8_t*>(s.data()), s.size_bytes()};
+}
+
 // Type-deducing helpers for constructing a span.
 template <typename T>
 constexpr span<T> make_span(T* data, size_t size) noexcept {
-- 
cgit v1.2.3