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#include "read_txt.h"
using namespace zen;
namespace
{
std::string detectLineBreak(const Zstring& filename) //throw FileError
{
//read a (hopefully) significant portion of data
zen::FileInput input(filename);
std::vector<char> buffer(64 * 1024);
size_t bytesRead = input.read(&buffer[0], buffer.size()); //throw FileError
buffer.resize(bytesRead);
//detect line break
std::string linebreakChars = "\r\n";
std::vector<char>::iterator iter = std::find_first_of(buffer.begin(), buffer.end(),
linebreakChars.begin(), linebreakChars.end());
if (iter != buffer.end())
{
if (*iter == '\r')
{
++iter;
if (iter != buffer.end())
{
if (*iter == '\n')
return "\r\n"; //Windows
else
return "\r"; //Mac
}
}
else if (*iter == '\n')
return "\n"; //Linux
}
//fallback
return "\n";
}
}
ExtractLines::ExtractLines(const Zstring& filename, const std::string& lineBreak) : //throw FileError
inputStream(filename), bufferLogBegin(buffer.begin()), lineBreak_(lineBreak)
{
if (lineBreak.empty())
lineBreak_ = detectLineBreak(filename); //throw FileError
}
bool ExtractLines::getLine(std::string& output) //throw FileError
{
for (;;)
{
//check if full line is in buffer
std::vector<char>::iterator iter = std::search(bufferLogBegin, buffer.end(), lineBreak_.begin(), lineBreak_.end());
if (iter != buffer.end())
{
output.assign(bufferLogBegin, iter);
bufferLogBegin = iter + lineBreak_.size();
return true;
}
buffer.erase(buffer.begin(), bufferLogBegin);
bufferLogBegin = buffer.begin();
//if done: cleanup
if (inputStream.eof())
{
if (buffer.empty())
return false;
output.assign(buffer.begin(), buffer.end());
buffer.clear();
return true;
}
//read next block
const size_t BLOCK_SIZE = 512 * 1024;
buffer.resize(buffer.size() + BLOCK_SIZE);
size_t bytesRead = inputStream.read(&buffer[0] + buffer.size() - BLOCK_SIZE, BLOCK_SIZE); //throw FileError
assert(bytesRead <= BLOCK_SIZE); //promised by FileInput()
if (bytesRead < BLOCK_SIZE)
buffer.resize(buffer.size() - (BLOCK_SIZE - bytesRead));
bufferLogBegin = buffer.begin();
}
}
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