Src/DasherCore/AbstractXMLParser.h

   1 /*
   2  *  AbstractXMLParser.h
   3  *  Dasher
   4  *
   5  *  Created by Alan Lawrence on 17/03/2011.
   6  *  Copyright 2011 Cavendish Laboratory. All rights reserved.
   7  *
   8  */
   9
  10 #ifndef __ABSTRACT_XML_PARSER_H__
  11 #define __ABSTRACT_XML_PARSER_H__
  12
  13 #include "../Common/Common.h"
  14 #ifdef HAVE_CONFIG_H
  15 #include <config.h>
  16 #endif
  17
  18 #include "Messages.h"
  19
  20 #include <string>
  21 #include <expat.h>
  22 #include <iostream>
  23
  24 class AbstractParser {
  25 public:
  26   AbstractParser(CMessageDisplay *pMsgs) : m_pMsgs(pMsgs) { }
  27   ///Utility method: constructs an ifstream to read from the specified file,
  28   /// then calls Parse(string&,istream&,bool) with the description 'file://strPath'
  29   virtual bool ParseFile(const std::string &strPath, bool bUser);
  30
  31   /// \param strDesc string to display to user to identify the source of this data,
  32   /// if there is an error. (Suggest: use a url, e.g. file://...)
  33   /// \param bUser if True, the file is from a user location (editable), false if from a
  34   /// system one. (Some subclasses treat the data differently according to which of these
  35   /// it is from.)
  36   virtual bool Parse(const std::string &strDesc, std::istream &in, bool bUser) = 0;
  37
  38 protected:
  39   ///The MessageDisplay to use to inform the user. Subclasses should use this
  40   /// too for any (e.g. semantic) errors they may detect.
  41   CMessageDisplay * const m_pMsgs;
  42 };
  43
  44 ///Basic wrapper over (Expat) XML Parser, handling file IO and wrapping C++
  45 /// virtual methods over C callbacks. Subclasses must implement methods to
  46 /// handle actual tags.
  47 class AbstractXMLParser : public AbstractParser {
  48 public:
  49   ///Parse (the whole) file - done in chunks to avoid loading the whole thing into memory.
  50   /// Any errors _besides_ file-not-found, will be passed to m_pMsgs as modal messages.
  51   virtual bool Parse(const std::string &strDesc, std::istream &in, bool bUser);
  52 protected:
  53   ///Create an AbstractXMLParser which will use the specified MessageDisplay to
  54   /// inform the user of any errors.
  55   AbstractXMLParser(CMessageDisplay *pMsgs);
  56
  57   ///Subclasses may call to get the description of the current file
  58   const std::string &GetDesc() {return m_strDesc;}
  59   ///Subclasses may call to determine if the current file is from a user location
  60   bool isUser();
  61
  62   ///Subclass should override to handle a start tag
  63   virtual void XmlStartHandler(const XML_Char *name, const XML_Char **atts)=0;
  64   ///Subclass should override to handle an end tag
  65   virtual void XmlEndHandler(const XML_Char *name)=0;
  66   ///Subclass may override to handle character data; the default implementation does nothing.
  67   ///\param str pointer to string data, note is NOT null-terminated
  68   ///\param len number of bytes to read from pointer
  69   virtual void XmlCData(const XML_Char *str, int len);
  70
  71   ///Utility function provided for subclasses wishing to perform XML _output_.
  72   // & to &amp;  < to &lt; and > to &gt;  and if (Attribute) ' to &apos; and " to &quot;
  73   /// \param Input string to escape, will be updated in-place.
  74   void XML_Escape(std::string &Input, bool Attribute);
  75 private:
  76   /// The actual callbacks passed to the expat library.
  77   /// These just convert the void* we passed to the library back into
  78   /// an instance pointer, to get a C++ class to work with a plain C library.
  79   static void XML_StartElement(void *userData, const XML_Char * name, const XML_Char ** atts);
  80   static void XML_EndElement(void *userData, const XML_Char * name);
  81   static void XML_CharacterData(void *userData, const XML_Char * s, int len);
  82   bool m_bUser;
  83   std::string m_strDesc;
  84 };
  85
  86 #endif