Expat

Stream oriented XML parser library with several useful features.

Website: https://libexpat.github.io
Platforms supported: Win32, Linux
Headers to include: expat.bi
Header version: 1.95.8
Examples: in examples/xml/

Example
   '' XML file parser command line tool based on libexpat

   '' Can use zstring or wstring (libexpat or libexpatw):
   '#define XML_UNICODE

   #include Once "expat.bi"
   #include Once "crt/mem.bi"

   #ifndef False
   #define False 0
   #endif
   #define NULL 0

   Const BUFFER_SIZE = 1024

   Type Context
      As Integer nesting
      As XML_char * (BUFFER_SIZE+1) text
      As Integer textlength
   End Type

   Dim Shared As Context ctx

   '' Callback called by libexpat when begin of XML tag is found
   Sub elementBegin cdecl _
      ( _
         ByVal userdata As Any Ptr, _
         ByVal element As Const XML_char Ptr, _
         ByVal attributes As Const XML_char Ptr Ptr _
      )

      '' Show its name
      Print Space(ctx.nesting);*element;

      '' and its attributes (attributes are given as an array of XML_char pointers
      '' much like argv, for each attribute there will apparently be the one
      '' element representing the name and a second element representing the
      '' specified value)
      While (*attributes)
         Print " ";**attributes;
         attributes += 1
         Print "='";**attributes;"'";
         attributes += 1
      Wend
      Print

      ctx.nesting += 1
      ctx.text[0] = 0
      ctx.textlength = 0
   End Sub

   '' Callback called by libexpat when end of XML tag is found
   Sub elementEnd cdecl(ByVal userdata As Any Ptr, ByVal element As Const XML_char Ptr)
      '' Show text collected in charData() callback below
      Print Space(ctx.nesting);ctx.text
      ctx.text[0] = 0
      ctx.textlength = 0
      ctx.nesting -= 1
   End Sub

   Sub charData cdecl _
      ( _
         ByVal userdata As Any Ptr, _
         ByVal chars As Const XML_char Ptr, _  '' Note: not null-terminated
         ByVal length As Integer _
      )

      '' This callback will apparently recieve every data between xml tags
      '' (really?), including newlines and space.

      '' Append to our buffer, if there still is free room, so we can print it out later
      If (length <= (BUFFER_SIZE - ctx.textlength)) Then
         memcpy(@ctx.text[ctx.textlength], @chars[0], length * SizeOf(XML_char))
         ctx.textlength += length
         ctx.text[ctx.textlength] = 0
      End If
   End Sub

   ''
   '' Main
   ''

      Dim As String filename = Command(1)
      If (Len(filename) = 0) Then
         Print "Usage: expat <xmlfilename>"
         End 1
      End If

      Dim As XML_Parser parser = XML_ParserCreate(NULL)
      If (parser = NULL) Then
         Print "XML_ParserCreate failed"
         End 1
      End If

      ''XML_SetUserData(parser, userdata_pointer)
      XML_SetElementHandler(parser, @elementBegin, @elementEnd)
      XML_SetCharacterDataHandler(parser, @charData)

      If (Open(filename, For Input, As #1)) Then
         Print "Could not open file: '";filename;"'"
         End 1
      End If

      Static As UByte buffer(0 To (BUFFER_SIZE-1))

      Dim As Integer reached_eof = False
      Do
         Dim As Integer size = BUFFER_SIZE
         Dim As Integer result = Get(#1, , buffer(0), size, size)
         If (result Or (size <= 0)) Then
            Print "File input error"
            End 1
         End If

         reached_eof = (EOF(1) <> False)

         If (XML_Parse(parser, @buffer(0), size, reached_eof) = False) Then
            Print filename & "(" & XML_GetCurrentLineNumber(parser) & "): Error from XML parser: "
            Print *XML_ErrorString(XML_GetErrorCode(parser))
            End 1
         End If
      Loop While (reached_eof = False)

      XML_ParserFree(parser)

