format_paragraph.cpp

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// format_paragraph.cpp

#include "format_paragraph.h"
#include "safe_assign.h"
#include <locale>
#include <iomanip>

format_paragraph::format_paragraph(
  const char* str,
  int left_col,
  int right_col,
  bool indent_first_line)
{
  safe_assign(m_text, str);
  m_left_col = left_col;
  m_right_col = right_col;
  m_indent_first_line = indent_first_line;
}

std::ostream& operator<< (std::ostream &os, const format_paragraph& fp)
{
  if (
    fp.m_left_col > fp.m_right_col ||
    fp.m_left_col < 0 ||
    fp.m_right_col < 0 ||
    fp.m_text.empty()
  )
    return os;
  os << std::left << std::setw(0) << std::setfill(' ');
  std::locale loc = os.getloc();
  std::string::size_type width = fp.m_right_col - fp.m_left_col +1;
  std::string::size_type start, end;
  std::string::size_type pos = 0;
  bool first_line = true;
  while(pos < fp.m_text.size())
  {
    // Skip leading whitespace except linefeed
    while(pos <= fp.m_text.size())
    {
      if (pos < fp.m_text.size() &&
        std::isspace(fp.m_text[pos], loc) &&
        fp.m_text[pos] != '\n'
      )
        pos++;
      else
        break;
    }
    if (pos >= fp.m_text.size())
      break;
    start = pos;
    end = std::string::npos;
    bool print = false;
    while (!print)
    {
      bool is_space = false;
      bool is_linefeed = false;
      bool is_end = false;
      while(pos <= fp.m_text.size() && !is_space && !is_linefeed && !is_end)
      {
        if (pos < fp.m_text.size())
        {
          char c = fp.m_text[pos];
          is_space = std::isspace(c, loc);
          is_linefeed = (c == '\n');
          if (is_space || is_linefeed)
            break;
          pos++;
        }
        else
          is_end = true;
      }
      // white-space, linefeed or string end at pos here
      if (pos - start > width)
      {
        // print using last known end if available
        if (end == std::string::npos)
          end = start + width;
        // move pos back
        pos = end;
        print = true;
      }
      else if (pos - start == width)
      {
        // print until this position
        print = true;
        end = pos;
      }
      else if (is_linefeed)
      {
        end = pos;
        print = true;
        pos++;
      }
      else if (is_end)
      {
        end = pos;
        print = true;
      }
      else
      {
        end = pos;
        pos++;
      }
    }
    int indent = fp.m_left_col;
    if (first_line)
    {
      if (!fp.m_indent_first_line)
        indent = 0;
      first_line = false;
    }
    if (indent > 0)
      os << std::setw(indent) << " ";
    os << fp.m_text.substr(start, end - start) << std::endl;
  }
  return os;
}

#ifdef _DEBUG
#include <iostream>
void test_fp(const char* psz, int left, int right, bool indent_first_line)
{
  std::cout << "left=" << left << ", right=" << right << ", indent=" << indent_first_line << std::endl;
  for (int i = 0; i <= right/10; ++i)
  {
    if (i > 0)
      std::cout << "        ";
    std::cout << std::right << std::setfill('0') << std::setw(2) << i;
  }
  std::cout << std::endl;
  int pos = 0;
  for (i = 0; i <= right; ++i)
  {
    std::cout << pos;
    pos++;
    if (pos > 9)
      pos = 0;
  }
  std::cout << std::endl;
  std::cout << format_paragraph(psz, left, right, indent_first_line);
  std::cout << "--" << std::endl;
}

void test_format_paragraph()
{
  const char* pszText = "This is a test of format_paragraph, which may be successful or otherwise disappointing to see. "
    "Ending line here.\n"
    "And continuing with more text. "
    "Several lines ending here.\n\n"
    "Text again.";
  test_fp("Spaces here.\n This is  a test. ", 0, 15, true);
  test_fp("Spaces here.    This is  a test.", 0, 15, true);
  test_fp(pszText, 0, 15, true);
  test_fp(pszText, 2, 15, true);
  test_fp(pszText, 2, 16, true);
  test_fp(pszText, 2, 78, true);
  test_fp(pszText, 2, 78, false);
  
}

/*
void main()
{
  test_format_paragraph();
}
*/

#endif _DEBUG

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