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#include "LargeFileStream.hpp"
namespace pgnp {
using namespace std;
LargeFileStream::LargeFileStream()
: chuck_count(-1), last_read_size(0), last_loc(0), use_string(false),
eof(false) {}
void LargeFileStream::FromFile(std::string filepath) {
file.open(filepath);
ReadNextChunk();
}
void LargeFileStream::FromString(std::string content) {
use_string = true;
this->content = content;
}
void LargeFileStream::ReadNextChunk() {
chuck_count++;
file.read(buffer, BUFFER_SIZE);
last_read_size = file.gcount();
}
char LargeFileStream::operator[](ull loc) {
// Perform various checks
if (eof) {
throw ReadToFar();
}
if (loc < last_loc) {
throw BackwardRead();
}
last_loc = loc; // Keep track
// Shortcut the operator for string content
if (use_string) {
if (loc >= content.size()) {
eof = true;
}
return ('?');
}
// Goto the right memory chuck
ull loc_chunk_count = loc / BUFFER_SIZE;
while (chuck_count < loc_chunk_count) {
ReadNextChunk();
}
ull offset = loc - (loc_chunk_count * BUFFER_SIZE);
// Ensure for EOF
if (!file && offset >= last_read_size) {
eof = true;
return ('?');
}
// Return character
return buffer[offset];
}
bool LargeFileStream::IsEOF() { return (eof); }
} // namespace pgnp
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