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// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_ZUCCHINI_IO_UTILS_H_
#define COMPONENTS_ZUCCHINI_IO_UTILS_H_
#include <stdint.h>
#include <cctype>
#include <istream>
#include <ostream>
#include <sstream>
#include <string>
namespace zucchini {
// An std::ostream wrapper that that limits number of std::endl lines to output,
// useful for preventing excessive debug message output. Usage requires some
// work by the caller. Sample:
// static LimitedOutputStream los(std::cerr, 10);
// if (!los.full()) {
// ... // Prepare message. Block may be skipped so don't do other work!
// los << message;
// los << std::endl; // Important!
// }
class LimitedOutputStream : public std::ostream {
private:
class StreamBuf : public std::stringbuf {
public:
StreamBuf(std::ostream& os, int limit);
~StreamBuf() override;
int sync() override;
bool full() const { return counter_ >= limit_; }
private:
std::ostream& os_;
const int limit_;
int counter_ = 0;
};
public:
LimitedOutputStream(std::ostream& os, int limit);
LimitedOutputStream(const LimitedOutputStream&) = delete;
const LimitedOutputStream& operator=(const LimitedOutputStream&) = delete;
bool full() const { return buf_.full(); }
private:
StreamBuf buf_;
};
// A class to render hexadecimal numbers for std::ostream with 0-padding. This
// is more concise and flexible than stateful STL manipulator alternatives; so:
// std::ios old_fmt(nullptr);
// old_fmt.copyfmt(std::cout);
// std::cout << std::uppercase << std::hex;
// std::cout << std::setfill('0') << std::setw(8) << int_data << std::endl;
// std::cout.copyfmt(old_fmt);
// can be expressed as:
// std::cout << AxHex<8>(int_data) << std::endl;
template <int N, typename T = uint32_t>
struct AsHex {
explicit AsHex(T value_in) : value(value_in) {}
T value;
};
template <int N, typename T>
std::ostream& operator<<(std::ostream& os, const AsHex<N, T>& as_hex) {
char buf[N + 1];
buf[N] = '\0';
T value = as_hex.value;
for (int i = N - 1; i >= 0; --i, value >>= 4)
buf[i] = "0123456789ABCDEF"[static_cast<int>(value & 0x0F)];
if (value)
os << "..."; // To indicate data truncation, or negative values.
os << buf;
return os;
}
// An output manipulator to simplify printing list separators. Sample usage:
// PrefixSep sep(",");
// for (int i : {3, 1, 4, 1, 5, 9})
// std::cout << sep << i;
// std::cout << std::endl; // Outputs "3,1,4,1,5,9\n".
class PrefixSep {
public:
explicit PrefixSep(const std::string& sep_str) : sep_str_(sep_str) {}
PrefixSep(const PrefixSep&) = delete;
const PrefixSep& operator=(const PrefixSep&) = delete;
friend std::ostream& operator<<(std::ostream& ostr, PrefixSep& obj);
private:
std::string sep_str_;
bool first_ = true;
};
// An input manipulator that dictates the expected next character in
// |std::istream|, and invalidates the stream if expectation is not met.
class EatChar {
public:
explicit EatChar(char ch) : ch_(ch) {}
EatChar(const EatChar&) = delete;
const EatChar& operator=(const EatChar&) = delete;
friend inline std::istream& operator>>(std::istream& istr,
const EatChar& obj) {
if (!istr.fail() && istr.get() != obj.ch_)
istr.setstate(std::ios_base::failbit);
return istr;
}
private:
char ch_;
};
// An input manipulator that reads an unsigned integer from |std::istream|,
// and invalidates the stream on failure. Intolerant of leading white spaces,
template <typename T>
class StrictUInt {
public:
explicit StrictUInt(T& var) : var_(var) {}
StrictUInt(const StrictUInt&) = default;
friend std::istream& operator>>(std::istream& istr, StrictUInt<T> obj) {
if (!istr.fail() && !::isdigit(istr.peek())) {
istr.setstate(std::ios_base::failbit);
return istr;
}
return istr >> obj.var_;
}
private:
T& var_;
};
// Stub out uint8_t: istream treats it as char, and value won't be read as int!
template <>
struct StrictUInt<uint8_t> {};
} // namespace zucchini
#endif // COMPONENTS_ZUCCHINI_IO_UTILS_H_
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