columnStrategy.hpp

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// Copyright (c) 2020-2025 Cody R. Drisko. All rights reserved.
// Licensed under the MIT License. See the LICENSE file in the project root for more information.
//
// Name: columnStrategy.hpp
// Author: crdrisko
// Date: 01/01/2021-14:15:57
// Description: An implementations of file parser for parsing data as columns
 
#ifndef DRYCHEM_COMMON_UTILITIES_INCLUDE_COMMON_UTILS_FILES_FILEPARSING_PARSERSTRATEGIES_COLUMNSTRATEGY_HPP
#define DRYCHEM_COMMON_UTILITIES_INCLUDE_COMMON_UTILS_FILES_FILEPARSING_PARSERSTRATEGIES_COLUMNSTRATEGY_HPP
 
#include <algorithm>
#include <cstddef>
#include <optional>
#include <string>
#include <vector>
 
#include "common-utils/strings/utils/tokenizer.hpp"
 
namespace CppUtils::Files
{
    class AsColumns
    {
    private:
        mutable std::vector<std::string> columnCache;
 
        void resetColumnsOnNewLine(std::size_t tokenIndex_, std::size_t& columnIndex_) const
        {
            // We only need to resize the vector once after we know the number of columns
            if (tokenIndex_ == columnIndex_)
                columnCache.resize(tokenIndex_);
 
            columnIndex_ = 0;
        }
 
        void trimTrainingSeparators() const
        {
            // clang-format off
            std::transform(columnCache.begin(), columnCache.end(), columnCache.begin(),
                [](const std::string& column) { return column.substr(0, column.size() - 1); });
            //clang-format on
        }
 
    public:
        auto operator()(
            const std::string& fileContents_, const std::optional<std::string>& fieldSeparator_ = std::nullopt) const
        {
            if (columnCache.empty())
            {
                std::string delimiters = fieldSeparator_.value_or("") + " \t\n";
 
                Strings::Tokenizer tok {fileContents_, delimiters, "\n"};
 
                auto tokens = tok.split();
                columnCache.resize(tokens.size());
 
                for (std::size_t i {}, j {}; i < tokens.size(); ++i)
                {
                    if (tokens[i] == "\n")
                    {
                        this->resetColumnsOnNewLine(i, j);
                        continue;
                    }
 
                    columnCache[j++].append(tokens[i]).append(fieldSeparator_.value_or("\t"));
                }
 
                this->trimTrainingSeparators();
            }
 
            return columnCache;
        }
    };
}   // namespace CppUtils::Files
 
 
#endif