io.cc

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#include "io.h"

#include <istream>
#include <ostream>
#include <fstream>
#include <stdexcept>
#include <cstdint>
#include <type_traits>
#include <cctype>

namespace tlz {

namespace {
    bool check_host_little_endian_() {
        union {
            std::uint16_t s;
            std::uint8_t c[2];
        } d;
        d.s = 1;
        return d.c[0] == 1;
    }
}


const line_delimitor default_line_delimitor = line_delimitor::LF;

const bool host_has_iec559_float =
    std::numeric_limits<float>::is_iec559 && std::numeric_limits<double>::is_iec559;

const bool host_is_little_endian = check_host_little_endian_();



line_delimitor detect_line_delimitor(std::istream& str, std::size_t max_offset) {
    std::size_t counter = 0;
    line_delimitor ld = line_delimitor::unknown;
    auto old_position = str.tellg();
    while(ld == line_delimitor::unknown) {
        if(++counter > max_offset) throw std::runtime_error("could not detect file line ending");
        char c;
        str.get(c);
        if(c == '\n') ld = line_delimitor::LF;
        else if(c == '\r') {
            if(str.peek() == '\n') ld = line_delimitor::CRLF;
            else ld = line_delimitor::CR;
        }
    }
    str.seekg(old_position);
    return ld;
}

void read_line(std::istream& str, std::string& line, line_delimitor ld) {
    if(ld == line_delimitor::unknown) throw std::invalid_argument("line delimitor not specified");
    
    if(ld == line_delimitor::CRLF) {
        std::getline(str, line, '\r');
        while(str.peek() != '\n') {
            std::string part_line;
            std::getline(str, part_line, '\r');
            line.append(1, '\r').append(part_line);
        }
        str.get();
    } else {
        std::getline(str, line, (ld == line_delimitor::LF ? '\n' : '\r'));
    }
}

void skip_line(std::istream& str, line_delimitor ld) {
    if(ld == line_delimitor::unknown) throw std::invalid_argument("line delimitor not specified");
    const auto max_count = std::numeric_limits<std::streamsize>::max();

    if(ld == line_delimitor::CRLF) {
        str.ignore(max_count, '\r');
        while(str.peek() != '\n') str.ignore(max_count, '\r');
        str.ignore();
    } else {
        str.ignore(max_count, (ld == line_delimitor::LF ? '\n' : '\r'));
    }
}


void write_line(std::ostream& str, const std::string& line, line_delimitor ld) {
    str << line;
    end_line(str, ld);
}


void end_line(std::ostream& str, line_delimitor ld) {
    switch(ld) {
        case line_delimitor::LF: str << '\n'; break;
        case line_delimitor::CR: str << '\r'; break;
        case line_delimitor::CRLF: str << "\r\n"; break;
        default: throw std::invalid_argument("line delimitor not specified");
    }
}




void flip_endianness(byte* data, std::size_t sz) {
    if(sz < 2) return;
    std::ptrdiff_t i = sz/2 - 1;
    std::ptrdiff_t o = sz - i - 1;
    while(i >= 0) std::swap(data[i--], data[o++]);
}


}