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// Copyright 2023 The Tint Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef SRC_TINT_UTILS_TEXT_STRING_STREAM_H_
#define SRC_TINT_UTILS_TEXT_STRING_STREAM_H_
#include <functional>
#include <iomanip>
#include <iterator>
#include <limits>
#include <sstream>
#include <string>
#include <utility>
#include "src/tint/utils/text/unicode.h"
namespace tint {
/// Stringstream wrapper which automatically resets the locale and sets floating point emission
/// settings needed for Tint.
class StringStream {
using SetWRetTy = decltype(std::setw(std::declval<int>()));
using SetPrecisionRetTy = decltype(std::setprecision(std::declval<int>()));
using SetFillRetTy = decltype(std::setfill(std::declval<char>()));
/// Evaluates to true if `T` is the return type of std::setw, std:setprecision or std::setfill.
template <typename T>
static constexpr bool IsSetType = std::is_same_v<SetWRetTy, std::decay_t<T>> ||
std::is_same_v<SetPrecisionRetTy, std::decay_t<T>> ||
std::is_same_v<SetFillRetTy, std::decay_t<T>>;
public:
/// @see tint::traits::IsOStream
static constexpr bool IsStreamWriter = true;
/// Constructor
StringStream();
/// Destructor
~StringStream();
/// @returns the format flags for the stream
std::ios_base::fmtflags flags() const { return sstream_.flags(); }
/// @param flags the flags to set
/// @returns the original format flags
std::ios_base::fmtflags flags(std::ios_base::fmtflags flags) { return sstream_.flags(flags); }
/// Emit `value` to the stream
/// @param value the value to emit
/// @returns a reference to this
template <typename T,
typename std::enable_if_t<std::is_integral_v<std::decay_t<T>>, bool> = true>
StringStream& operator<<(T&& value) {
return EmitValue(std::forward<T>(value));
}
/// Emit `value` to the stream
/// @param value the value to emit
/// @returns a reference to this
StringStream& operator<<(const char* value) { return EmitValue(value); }
/// Emit `value` to the stream
/// @param value the value to emit
/// @returns a reference to this
StringStream& operator<<(const std::string& value) { return EmitValue(value); }
/// Emit `value` to the stream
/// @param value the value to emit
/// @returns a reference to this
StringStream& operator<<(std::string_view value) { return EmitValue(value); }
/// Emit `value` to the stream
/// @param value the value to emit
/// @returns a reference to this
StringStream& operator<<(const void* value) { return EmitValue(value); }
/// Emit `value` to the stream
/// @param value the value to emit
/// @returns a reference to this
template <typename T,
typename std::enable_if_t<std::is_floating_point_v<std::decay_t<T>>, bool> = true>
StringStream& operator<<(T&& value) {
return EmitFloat(std::forward<T>(value));
}
/// Emit `value` to the stream
/// @param value the value to emit
/// @returns a reference to this
template <typename T>
StringStream& EmitValue(T&& value) {
sstream_ << std::forward<T>(value);
return *this;
}
/// Emit `value` to the stream
/// @param value the value to emit
/// @returns a reference to this
template <typename T>
StringStream& EmitFloat(const T& value) {
// Try printing the float in fixed point, with a smallish limit on the precision
std::stringstream fixed;
fixed.flags(fixed.flags() | std::ios_base::showpoint | std::ios_base::fixed);
fixed.imbue(std::locale::classic());
fixed.precision(20);
fixed << value;
std::string str = fixed.str();
// If this string can be parsed without loss of information, use it.
// (Use double here to dodge a bug in older libc++ versions which would incorrectly read
// back FLT_MAX as INF.)
double roundtripped;
fixed >> roundtripped;
// Strip trailing zeros from the number.
auto float_equal_no_warning = std::equal_to<T>();
if (float_equal_no_warning(value, static_cast<T>(roundtripped))) {
while (str.length() >= 2 && str[str.size() - 1] == '0' && str[str.size() - 2] != '.') {
str.pop_back();
}
sstream_ << str;
return *this;
}
// Resort to scientific, with the minimum precision needed to preserve the whole float
std::stringstream sci;
sci.imbue(std::locale::classic());
sci.precision(std::numeric_limits<T>::max_digits10);
sci << value;
sstream_ << sci.str();
return *this;
}
/// Swaps streams
/// @param other stream to swap too
void swap(StringStream& other) { sstream_.swap(other.sstream_); }
/// repeat queues the character c to be written to the printer n times.
/// @param c the character to print `n` times
/// @param n the number of times to print character `c`
void repeat(char c, size_t n) { std::fill_n(std::ostream_iterator<char>(sstream_), n, c); }
/// The callback to emit a `endl` to the stream
using StdEndl = std::ostream& (*)(std::ostream&);
/// @param manipulator the callback to emit too
/// @returns a reference to this
StringStream& operator<<(StdEndl manipulator) {
// call the function, and return it's value
manipulator(sstream_);
return *this;
}
/// @param manipulator the callback to emit too
/// @returns a reference to this
StringStream& operator<<(decltype(std::hex) manipulator) {
// call the function, and return it's value
manipulator(sstream_);
return *this;
}
/// @param value the value to emit
/// @returns a reference to this
template <typename T, typename std::enable_if_t<IsSetType<T>, int> = 0>
StringStream& operator<<(T&& value) {
// call the function, and return it's value
sstream_ << std::forward<T>(value);
return *this;
}
/// @returns the current location in the output stream
uint32_t tellp() { return static_cast<uint32_t>(sstream_.tellp()); }
/// @returns the string contents of the stream
std::string str() const { return sstream_.str(); }
private:
std::stringstream sstream_;
};
/// Writes the CodePoint to the stream.
/// @param out the stream to write to
/// @param codepoint the CodePoint to write
/// @returns out so calls can be chained
StringStream& operator<<(StringStream& out, CodePoint codepoint);
} // namespace tint
#endif // SRC_TINT_UTILS_TEXT_STRING_STREAM_H_