rcpp_framework/libs/maddy/blockparser.h

/*
 * This project is licensed under the MIT license. For more information see the
 * LICENSE file.
 */
#pragma once

// -----------------------------------------------------------------------------

#include <functional>
#include <sstream>
#include <string>
// windows compatibility includes
#include <cctype>
#include <algorithm>

// -----------------------------------------------------------------------------

namespace maddy {

// -----------------------------------------------------------------------------

/**
 * BlockParser
 *
 * The code expects every child to have the following static function to be
 * implemented:
 * `static bool IsStartingLine(const std::string& line)`
 *
 * @class
 */
class BlockParser
{
public:
  /**
   * ctor
   *
   * @method
   * @param {std::function<void(std::string&)>} parseLineCallback
   * @param {std::function<std::shared_ptr<BlockParser>(const std::string& line)>} getBlockParserForLineCallback
   */
  BlockParser(
    std::function<void(std::string&)> parseLineCallback,
    std::function<std::shared_ptr<BlockParser>(const std::string& line)> getBlockParserForLineCallback
  )
    : result("", std::ios_base::ate | std::ios_base::in | std::ios_base::out)
    , childParser(nullptr)
    , parseLineCallback(parseLineCallback)
    , getBlockParserForLineCallback(getBlockParserForLineCallback)
  {}

  /**
   * dtor
   *
   * @method
   */
  virtual ~BlockParser() {}

  /**
   * AddLine
   *
   * Adding a line which has to be parsed.
   *
   * @method
   * @param {std::string&} line
   * @return {void}
   */
  virtual void
  AddLine(std::string& line)
  {
    this->parseBlock(line);

    if (this->isInlineBlockAllowed() && !this->childParser)
    {
      this->childParser = this->getBlockParserForLine(line);
    }

    if (this->childParser)
    {
      this->childParser->AddLine(line);

      if (this->childParser->IsFinished())
      {
        this->result << this->childParser->GetResult().str();
        this->childParser = nullptr;
      }

      return;
    }

    if (this->isLineParserAllowed())
    {
      this->parseLine(line);
    }

    this->result << line;
  }

  /**
   * IsFinished
   *
   * Check if the BlockParser is done
   *
   * @method
   * @return {bool}
   */
  virtual bool IsFinished() const = 0;

  /**
   * GetResult
   *
   * Get the parsed HTML output.
   *
   * @method
   * @return {std::stringstream}
   */
  std::stringstream&
  GetResult()
  {
    return this->result;
  }

  /**
   * Clear
   *
   * Clear the result to reuse the parser object.
   *
   * It is only used by one test for now.
   *
   * @method
   * @return {void}
   */
  void
  Clear()
  {
    this->result.str("");
  }

protected:
  std::stringstream result;
  std::shared_ptr<BlockParser> childParser;

  virtual bool isInlineBlockAllowed() const = 0;
  virtual bool isLineParserAllowed() const = 0;
  virtual void parseBlock(std::string& line) = 0;

  void
  parseLine(std::string& line)
  {
    if (parseLineCallback)
    {
      parseLineCallback(line);
    }
  }

  uint32_t
  getIndentationWidth(const std::string& line) const
  {
    bool hasMetNonSpace = false;

    uint32_t indentation = static_cast<uint32_t>(
      std::count_if(
        line.begin(),
        line.end(),
        [&hasMetNonSpace](unsigned char c)
        {
          if (hasMetNonSpace)
          {
            return false;
          }

          if (std::isspace(c))
          {
            return true;
          }

          hasMetNonSpace = true;
          return false;
        }
      )
    );

    return indentation;
  }

  std::shared_ptr<BlockParser>
  getBlockParserForLine(const std::string& line)
  {
    if (getBlockParserForLineCallback)
    {
      return getBlockParserForLineCallback(line);
    }

    return nullptr;
  }

private:
  std::function<void(std::string&)> parseLineCallback;
  std::function<std::shared_ptr<BlockParser>(const std::string& line)> getBlockParserForLineCallback;
}; // class BlockParser

// -----------------------------------------------------------------------------

} // namespace maddy