From fd34a3d246b05512a471246406a92063bb3d9192 Mon Sep 17 00:00:00 2001
From: Alexey Ochapov <alexez@alexez.com>
Date: Fri, 27 Aug 2021 00:52:41 +0300
Subject: [PATCH] make detail::basic_memory_buffer constexpr with C++20
---
include/fmt/core.h | 42 ++++++++++++++++++++++++++----------------
include/fmt/format.h | 36 ++++++++++++++++++++----------------
2 files changed, 46 insertions(+), 32 deletions(-)
diff --git a/include/fmt/core.h b/include/fmt/core.h
index bb67a9ea..b0405ee4 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -100,6 +100,13 @@
# define FMT_CONSTEXPR_DECL
#endif
+#if __cplusplus >= 202002L || \
+ (__cplusplus >= 201709L && FMT_GCC_VERSION >= 1002)
+# define FMT_CONSTEXPR20 constexpr
+#else
+# define FMT_CONSTEXPR20
+#endif
+
// Check if constexpr std::char_traits<>::compare,length is supported.
#if defined(__GLIBCXX__)
# if __cplusplus >= 201703L && defined(_GLIBCXX_RELEASE) && \
@@ -773,22 +780,22 @@ template <typename T> class buffer {
FMT_MSC_WARNING(suppress : 26495)
buffer(size_t sz) FMT_NOEXCEPT : size_(sz), capacity_(sz) {}
- buffer(T* p = nullptr, size_t sz = 0, size_t cap = 0) FMT_NOEXCEPT
- : ptr_(p),
- size_(sz),
- capacity_(cap) {}
+ FMT_CONSTEXPR20 buffer(T* p = nullptr, size_t sz = 0,
+ size_t cap = 0) FMT_NOEXCEPT : ptr_(p),
+ size_(sz),
+ capacity_(cap) {}
- ~buffer() = default;
+ FMT_CONSTEXPR20 ~buffer() = default;
buffer(buffer&&) = default;
/** Sets the buffer data and capacity. */
- void set(T* buf_data, size_t buf_capacity) FMT_NOEXCEPT {
+ FMT_CONSTEXPR void set(T* buf_data, size_t buf_capacity) FMT_NOEXCEPT {
ptr_ = buf_data;
capacity_ = buf_capacity;
}
/** Increases the buffer capacity to hold at least *capacity* elements. */
- virtual void grow(size_t capacity) = 0;
+ virtual FMT_CONSTEXPR20 void grow(size_t capacity) = 0;
public:
using value_type = T;
@@ -804,23 +811,23 @@ template <typename T> class buffer {
auto end() const FMT_NOEXCEPT -> const T* { return ptr_ + size_; }
/** Returns the size of this buffer. */
- auto size() const FMT_NOEXCEPT -> size_t { return size_; }
+ constexpr auto size() const FMT_NOEXCEPT -> size_t { return size_; }
/** Returns the capacity of this buffer. */
- auto capacity() const FMT_NOEXCEPT -> size_t { return capacity_; }
+ constexpr auto capacity() const FMT_NOEXCEPT -> size_t { return capacity_; }
/** Returns a pointer to the buffer data. */
- auto data() FMT_NOEXCEPT -> T* { return ptr_; }
+ FMT_CONSTEXPR auto data() FMT_NOEXCEPT -> T* { return ptr_; }
/** Returns a pointer to the buffer data. */
- auto data() const FMT_NOEXCEPT -> const T* { return ptr_; }
+ FMT_CONSTEXPR auto data() const FMT_NOEXCEPT -> const T* { return ptr_; }
/** Clears this buffer. */
void clear() { size_ = 0; }
// Tries resizing the buffer to contain *count* elements. If T is a POD type
// the new elements may not be initialized.
- void try_resize(size_t count) {
+ FMT_CONSTEXPR20 void try_resize(size_t count) {
try_reserve(count);
size_ = count <= capacity_ ? count : capacity_;
}
@@ -829,11 +836,11 @@ template <typename T> class buffer {
// capacity by a smaller amount than requested but guarantees there is space
// for at least one additional element either by increasing the capacity or by
// flushing the buffer if it is full.
- void try_reserve(size_t new_capacity) {
+ FMT_CONSTEXPR20 void try_reserve(size_t new_capacity) {
if (new_capacity > capacity_) grow(new_capacity);
}
- void push_back(const T& value) {
+ FMT_CONSTEXPR20 void push_back(const T& value) {
try_reserve(size_ + 1);
ptr_[size_++] = value;
}
@@ -841,8 +848,11 @@ template <typename T> class buffer {
/** Appends data to the end of the buffer. */
template <typename U> void append(const U* begin, const U* end);
- template <typename I> auto operator[](I index) -> T& { return ptr_[index]; }
- template <typename I> auto operator[](I index) const -> const T& {
+ template <typename I> FMT_CONSTEXPR auto operator[](I index) -> T& {
+ return ptr_[index];
+ }
+ template <typename I>
+ FMT_CONSTEXPR auto operator[](I index) const -> const T& {
return ptr_[index];
}
};
diff --git a/include/fmt/format.h b/include/fmt/format.h
index 117c91dd..4d414087 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -249,14 +249,6 @@ FMT_END_NAMESPACE
FMT_BEGIN_NAMESPACE
namespace detail {
-
-#if __cplusplus >= 202002L || \
- (__cplusplus >= 201709L && FMT_GCC_VERSION >= 1002)
-# define FMT_CONSTEXPR20 constexpr
-#else
-# define FMT_CONSTEXPR20
-#endif
-
// An equivalent of `*reinterpret_cast<Dest*>(&source)` that doesn't have
// undefined behavior (e.g. due to type aliasing).
// Example: uint64_t d = bit_cast<uint64_t>(2.718);
@@ -644,7 +636,7 @@ class basic_memory_buffer final : public detail::buffer<T> {
Allocator alloc_;
// Deallocate memory allocated by the buffer.
- void deallocate() {
+ FMT_CONSTEXPR20 void deallocate() {
T* data = this->data();
if (data != store_) alloc_.deallocate(data, this->capacity());
}
@@ -656,22 +648,31 @@ class basic_memory_buffer final : public detail::buffer<T> {
using value_type = T;
using const_reference = const T&;
- explicit basic_memory_buffer(const Allocator& alloc = Allocator())
+ FMT_CONSTEXPR20 explicit basic_memory_buffer(
+ const Allocator& alloc = Allocator())
: alloc_(alloc) {
this->set(store_, SIZE);
+ if (detail::is_constant_evaluated()) {
+ detail::fill_n(store_, SIZE, T{});
+ }
}
- ~basic_memory_buffer() { deallocate(); }
+ FMT_CONSTEXPR20 ~basic_memory_buffer() { deallocate(); }
private:
// Move data from other to this buffer.
- void move(basic_memory_buffer& other) {
+ FMT_CONSTEXPR20 void move(basic_memory_buffer& other) {
alloc_ = std::move(other.alloc_);
T* data = other.data();
size_t size = other.size(), capacity = other.capacity();
if (data == other.store_) {
this->set(store_, capacity);
- std::uninitialized_copy(other.store_, other.store_ + size,
- detail::make_checked(store_, capacity));
+ if (detail::is_constant_evaluated()) {
+ detail::copy_str<T>(other.store_, other.store_ + size,
+ detail::make_checked(store_, capacity));
+ } else {
+ std::uninitialized_copy(other.store_, other.store_ + size,
+ detail::make_checked(store_, capacity));
+ }
} else {
this->set(data, capacity);
// Set pointer to the inline array so that delete is not called
@@ -688,7 +689,10 @@ class basic_memory_buffer final : public detail::buffer<T> {
of the other object to it.
\endrst
*/
- basic_memory_buffer(basic_memory_buffer&& other) FMT_NOEXCEPT { move(other); }
+ FMT_CONSTEXPR20 basic_memory_buffer(basic_memory_buffer&& other)
+ FMT_NOEXCEPT {
+ move(other);
+ }
/**
\rst
@@ -710,7 +714,7 @@ class basic_memory_buffer final : public detail::buffer<T> {
Resizes the buffer to contain *count* elements. If T is a POD type new
elements may not be initialized.
*/
- void resize(size_t count) { this->try_resize(count); }
+ FMT_CONSTEXPR20 void resize(size_t count) { this->try_resize(count); }
/** Increases the buffer capacity to *new_capacity*. */
void reserve(size_t new_capacity) { this->try_reserve(new_capacity); }