yaml_parser.cpp

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/* ==============================================================================================================================
 
   This file is part of CoastalME, the Coastal Modelling Environment.
 
   CoastalME 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 3 of the License, 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; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
==============================================================================================================================*/
#include "yaml_parser.h"
#include <iostream>
#include <sstream>
#include <algorithm>
#include <cctype>
 
using std::cerr;
using std::endl;
using std::getline;
using std::isspace;
using std::stod;
using std::stoi;
using std::stringstream;
 
//===============================================================================================================================
// CYamlNode implementation
//===============================================================================================================================
CYamlNode::CYamlNode() : m_bIsSequence(false)
{
}
 
CYamlNode::~CYamlNode()
{
}
 
void CYamlNode::SetValue(string const& strValue)
{
   m_strValue = strValue;
}
 
void CYamlNode::AddChild(string const& strKey, CYamlNode const& node)
{
   m_mapChildren[strKey] = node;
}
 
void CYamlNode::AddSequenceItem(CYamlNode const& node)
{
   m_vecChildren.push_back(node);
   m_bIsSequence = true;
}
 
string CYamlNode::GetValue() const
{
   return m_strValue;
}
 
bool CYamlNode::HasChild(string const& strKey) const
{
   return m_mapChildren.find(strKey) != m_mapChildren.end();
}
 
CYamlNode CYamlNode::GetChild(string const& strKey) const
{
   auto it = m_mapChildren.find(strKey);
   if (it != m_mapChildren.end())
      return it->second;
   return CYamlNode();      // Return empty node if not found
}
 
vector<CYamlNode> CYamlNode::GetSequence() const
{
   return m_vecChildren;
}
 
bool CYamlNode::IsSequence() const
{
   return m_bIsSequence;
}
 
int CYamlNode::GetSequenceSize() const
{
   return static_cast<int>(m_vecChildren.size());
}
 
int CYamlNode::GetIntValue(int nDefault) const
{
   try
   {
      if (! m_strValue.empty())
         return stoi(m_strValue);
   }
   catch (...)
   {
      // Return default on conversion error
   }
   return nDefault;
}
 
double CYamlNode::GetDoubleValue(double dDefault) const
{
   try
   {
      if (! m_strValue.empty())
         return stod(m_strValue);
   }
   catch (...)
   {
      // Return default on conversion error
   }
   return dDefault;
}
 
bool CYamlNode::GetBoolValue(bool bDefault) const
{
   if (m_strValue.empty())
      return bDefault;
 
   string strLower = m_strValue;
   std::transform(strLower.begin(), strLower.end(), strLower.begin(), ::tolower);
 
   if (strLower == "true" || strLower == "yes" || strLower == "y" || strLower == "1")
      return true;
   else if (strLower == "false" || strLower == "no" || strLower == "n" || strLower == "0")
      return false;
 
   return bDefault;
}
 
vector<string> CYamlNode::GetStringSequence() const
{
   vector<string> vecResult;
   for (auto const& node : m_vecChildren)
   {
      vecResult.push_back(node.GetValue());
   }
   return vecResult;
}
 
//===============================================================================================================================
// CYamlParser implementation
//===============================================================================================================================
CYamlParser::CYamlParser() : m_nCurrentLine(0)
{
}
 
CYamlParser::~CYamlParser()
{
}
 
bool CYamlParser::bParseFile(string const& strFileName)
{
   m_strFileName = strFileName;
   m_nCurrentLine = 0;
   m_strError.clear();
 
   ifstream fileStream(strFileName);
   if (! fileStream.is_open())
   {
      m_strError = "Cannot open file: " + strFileName;
      return false;
   }
 
   try
   {
      m_RootNode = ParseSection(fileStream, -1);
   }
   catch (std::exception const& e)
   {
      m_strError = "Parse error at line " + std::to_string(m_nCurrentLine) + ": " + e.what();
      return false;
   }
 
   fileStream.close();
   return true;
}
 
CYamlNode CYamlParser::GetRoot() const
{
   return m_RootNode;
}
 
string CYamlParser::GetError() const
{
   return m_strError;
}
 
bool CYamlParser::bHasError() const
{
   return ! m_strError.empty();
}
 
int CYamlParser::nGetIndentLevel(string const& strLine) const
{
   int nIndent = 0;
   for (char c : strLine)
   {
      if (c == ' ')
         nIndent++;
      else if (c == '\t')
         nIndent += 4;      // Treat tab as 4 spaces
      else
         break;
   }
   return nIndent;
}
 
string CYamlParser::strTrimLeft(string const& strLine) const
{
   auto it = strLine.begin();
   while (it != strLine.end() && isspace(*it))
      it++;
   return string(it, strLine.end());
}
 
string CYamlParser::strTrimRight(string const& strLine) const
{
   auto it = strLine.rbegin();
   while (it != strLine.rend() && isspace(*it))
      it++;
   return string(strLine.begin(), it.base());
}
 
string CYamlParser::strTrim(string const& strLine) const
{
   return strTrimLeft(strTrimRight(strLine));
}
 
bool CYamlParser::bIsComment(string const& strLine) const
{
   string strTrimmed = strTrimLeft(strLine);
   return strTrimmed.empty() || strTrimmed[0] == '#';
}
 
bool CYamlParser::bIsEmpty(string const& strLine) const
{
   return strTrim(strLine).empty();
}
 
bool CYamlParser::bParseLine(string const& strLine, string& strKey, string& strValue, bool& bIsSequence) const
{
   string strTrimmed = strTrimLeft(strLine);
   bIsSequence = false;
 
   // Check for sequence item
   if (strTrimmed.length() > 0 && strTrimmed[0] == '-')
   {
      bIsSequence = true;
      strKey.clear();
      strValue = strTrim(strTrimmed.substr(1));
      strValue = strRemoveQuotes(strValue);
      return true;
   }
 
   // Look for key-value pair
   size_t nColonPos = strTrimmed.find(':');
   if (nColonPos == string::npos)
      return false;
 
   strKey = strTrim(strTrimmed.substr(0, nColonPos));
   if (nColonPos + 1 < strTrimmed.length())
      strValue = strTrim(strTrimmed.substr(nColonPos + 1));
   else
      strValue.clear();
 
   // Remove quotes from string values
   strValue = strRemoveQuotes(strValue);
 
   return true;
}
 
string CYamlParser::strRemoveQuotes(string const& strValue) const
{
   string result = strValue;
 
   // Remove surrounding double quotes
   if (result.length() >= 2 && result.front() == '"' && result.back() == '"')
   {
      result = result.substr(1, result.length() - 2);
   }
   // Remove surrounding single quotes
   else if (result.length() >= 2 && result.front() == '\'' && result.back() == '\'')
   {
      result = result.substr(1, result.length() - 2);
   }
 
   return result;
}
 
CYamlNode CYamlParser::ParseSection(ifstream& fileStream, int nBaseIndent)
{
   CYamlNode currentNode;
   string strLine;
 
   while (getline(fileStream, strLine))
   {
      m_nCurrentLine++;
 
      // Skip comments and empty lines
      if (bIsComment(strLine) || bIsEmpty(strLine))
         continue;
 
      int nIndent = nGetIndentLevel(strLine);
 
      // If we've gone back to a lower indentation level, we're done with this section
      if (nBaseIndent >= 0 && nIndent <= nBaseIndent)
      {
         // Put the line back for the parent to process
         fileStream.seekg(static_cast<int>(fileStream.tellg()) - static_cast<int>(strLine.length()) - 1);
         m_nCurrentLine--;
         break;
      }
 
      string strKey, strValue;
      bool bIsSequence;
 
      if (bParseLine(strLine, strKey, strValue, bIsSequence))
      {
         if (bIsSequence)
         {
            // Handle sequence item
            CYamlNode itemNode;
            if (! strValue.empty())
            {
               itemNode.SetValue(strValue);
            }
            else
            {
               // Multi-line sequence item
               itemNode = ParseSection(fileStream, nIndent);
            }
            currentNode.AddSequenceItem(itemNode);
         }
         else
         {
            // Handle key-value pair
            CYamlNode childNode;
            if (! strValue.empty())
            {
               childNode.SetValue(strValue);
            }
            else
            {
               // Multi-line value
               childNode = ParseSection(fileStream, nIndent);
            }
            currentNode.AddChild(strKey, childNode);
         }
      }
   }
 
   return currentNode;
}