portapack-mayhem/firmware/application/file_reader.hpp
Kyle Reed 497ca3f934
Refactor freqman_db parsing (#1244)
* WIP freqman changes/memory perf/stash
* Split ui tone_key function out for testing.
* Add more tests and fix bugs.
* Use default max_entries in recond
* Set limit back to 90 for now
2023-07-08 22:04:12 +02:00

152 lines
4.0 KiB
C++

/*
* Copyright (C) 2023 Kyle Reed
*
* This file is part of PortaPack.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef __FILE_READER_HPP__
#define __FILE_READER_HPP__
#include "file.hpp"
#include <cstring>
#include <cstdlib>
#include <string>
#include <string_view>
#include <vector>
/* BufferType requires the following members
* Size size()
* Result<Size> read(void* data, Size bytes_to_read)
* Result<Offset> seek(uint32_t offset)
*/
/* Iterates lines in buffer split on '\n'.
* NB: very basic iterator impl, don't try anything fancy with it.
* For example, you _must_ deref the iterator after advancing it. */
template <typename BufferType>
class BufferLineReader {
public:
struct iterator {
bool operator!=(const iterator& other) {
return this->pos_ != other.pos_ || this->reader_ != other.reader_;
}
const std::string& operator*() {
if (!cached_) {
bool ok = reader_->read_line(*this);
cached_ = true;
if (!ok) *this = reader_->end();
}
return line_data_;
}
iterator& operator++() {
const auto size = reader_->size();
if (pos_ < size) {
cached_ = false;
pos_ += line_data_.length();
}
if (pos_ >= size)
*this = reader_->end();
return *this;
}
typename BufferType::Size pos_{};
BufferLineReader* reader_{};
bool cached_ = false;
std::string line_data_{};
};
BufferLineReader(BufferType& buffer)
: buffer_{buffer} {}
iterator begin() { return {0, this}; }
iterator end() { return {size(), this}; }
typename BufferType::Size size() const { return buffer_.size(); }
private:
BufferType& buffer_;
bool read_line(iterator& it) {
constexpr size_t buf_size = 0x80;
char buf[buf_size];
uint32_t offset = 0;
it.line_data_.resize(buf_size);
buffer_.seek(it.pos_);
while (true) {
auto read = buffer_.read(buf, buf_size);
if (!read)
return false;
// Find newline.
auto len = 0u;
for (; len < *read; ++len) {
if (buf[len] == '\n') {
++len;
break;
}
}
// Reallocate if needed.
if (offset + len >= it.line_data_.length())
it.line_data_.resize(offset + len);
std::strncpy(&it.line_data_[offset], buf, len);
offset += len;
if (len < buf_size)
break;
}
it.line_data_.resize(offset);
return true;
}
};
using FileLineReader = BufferLineReader<File>;
/* Splits the string on the specified char and returns
* a vector of string_views. NB: the lifetime of the
* string to split must be maintained while the views
* are used or they will dangle. */
std::vector<std::string_view> split_string(std::string_view str, char c);
/* Returns the number of lines in a file. */
template <typename BufferType>
uint32_t count_lines(BufferLineReader<BufferType>& reader) {
uint32_t count = 0;
auto it = reader.begin();
do {
*it; // Necessary to force the file read.
++count;
} while (++it != reader.end());
return count;
}
#endif