A simple STL based XML parser

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This is a small XML parser, based purely on STL. There are two main classes XmlStream and XmlParser. XmlParser.h contains most of the parsing code. It has several state variable, which can be split up into two categories:

1. Buffer state - Shows where we are parsing from
2. Parsing state - Shows what we have found

XmlParser makes extensive use of offsets to keep track of its state. This is done by design. In order to maximize speed it does not do any string copies.

To start parsing declare an instance of the class XmlStream and setup the buffer that you want to parse. An example is included in Parser.cpp. Call parse in XmlStream, passing in a pointer to the buffer and the buffers length. You will see screen output showing what has been found. This is simple debug output and can be turned off.

XmlNotify is used as an interface class to notify a subscriber of nodes and elements being found. There is a pointer to a subscriber in the XmlStream class. The subscriber can be set using setSubscriber.

Notice that no XML document declaration is included nor is a schema included. If those exist in your buffer don't send them to the parser. Later, the ability to remove these, will added in the code to step through these. so this is a non-validating parser. There is one bug in the parser. When an empty node is encountered it will be reported as an element this will be fixed later. An example of this is included in the sample code.

If you have any suggestions or improvements let me know.

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How to parse XML file Rajiv_cn 0:05 15 Jul '08   Hi to Everyone, First Thank a lot for this code. Now I am a beginner in this XML parsing area. I want to parse an XML file so what i need to do ? I am looking forward from you. Thanks & Regards, Rajiv Sign In·View Thread·PermaLink 1.50/5 (2 votes) Hi. I want your help, David. Choi so-dam 15:38 23 Apr '08   Hi, First of all, Thanks for your posting. I hope to use your code for my own code. Now, I wonder about your code's license, whether it takes "CPOL" or not. Waiting for your reply. Thank you. Sign In·View Thread·PermaLink Here with Standard C++ only... pietrom 6:28 14 Dec '06   This program is not a Standard C++ program because of the non standard libraries it uses. Anyway it is really easy to make it use the STL only. I did it and it seems to work (using gcc). I cannot find a way to attach a file from here, so if someone should be interested, just let me know and I will send you the code directly. --> pietromele@yahoo.com Sign In·View Thread·PermaLink 1.33/5 (3 votes) Compiling using MinGW Emili___ 3:50 3 Mar '06   I needed to modify something to compile (using Code::Blocks) with mingw. First of all, I couldn't use atlbase.h I defined only windows.h. Second, I had to change this kind of lines in XMLParser.h: string::iterator start = _buffer + offset; for this: string::iterator start = ((string)_buffer).begin() + offset; That's all. Thanks for your code Sign In·View Thread·PermaLink 2.00/5 (1 vote) vc2005 compatibility? BryanWilkins 11:42 19 Dec '05   has anyone tried to make this code run on vc2005? I get alot of cannot convert type string to iterator etc etc... I finally got around the problems by not using this code, but I find myself wondering why the new compiler is so string on converting pointers to iterators. Bryan Sign In·View Thread·PermaLink 2.00/5 (9 votes) Re: vc2005 compatibility? Jeff_rowa 2:24 22 Nov '06   Hi Bryan, I have the same problem, whenever I want to compile the project under VS2005 I get lots can't convert error, could you say what did u do or post your code here please. Regards, Sign In·View Thread·PermaLink 1.20/5 (4 votes) W3C compliance Umut Alev 22:04 25 Jul '05   Perhaps this has been talked a lot but I can not stop my self from writing this. One of the reasons of XML is connecting platforms, apps through text encoded messages, to achieve this you need compliance. Implementing a fully (95%-98%) compliant XML parser is really hard. Usually an average Dev can get to 80% pretty quickly and the experienced can get to %90. The rest is all egde cases and getting them right requires extensive testing suites to ensure compat between different platforms. I know this by experience. There are quite a few xml parser implementations out there. Users are usually best served when the xml parser implementations are recognized by the W3C Recommendations. Other implementations can not go any further than academic studies as the cost of them making interop with the rest of the world sky rockets as dev's are trying to achieve %95 compat. Sign In·View Thread·PermaLink 2.33/5 (3 votes) How do you I get attribute value ? khmerkidnow 15:07 29 Jul '04   If I have xml scheme like below and I like to get the attribute value such as 22805, SA287430035 or ENV_LAN_1. How would I do it? thank in advance. -------------------------------------------------------------------------------- <?xml version="1.0" encoding="utf-8"?> <LOADBOX> <row BoxID="22805" BoxSerialNumber="SA287430035" BoxTest="ENV_LAN_1"> <row BoxID="77688" BoxSerialNumber="SA287460015" BoxTest="ENV_LAN_5"> <row BoxID="15141" BoxSerialNumber="HK184700609" BoxTest="ENV1"> </LOADBOX> Sign In·View Thread·PermaLink 3.00/5 (7 votes) Re: How do you I get attribute value ? dbpradeep 1:29 19 Mar '09   Me too require solution for the same problem. Can anyone help!! I use java. Sign In·View Thread·PermaLink multiple entries of the same name burnettb317 12:58 14 Jul '03   thanks for the great XML tools, they are very easy to use. I would like to have a table represented in XML but this implementation of the parser doesn't handle multiple entries of the same name, for example: <HOST> <NAME>cod</NAME> <DNSNAME>cod.somecorp.com</DNSNAME> <NIC>    <MAC>0040f4612820</MAC>    <IP>192.168.172.54</IP>    <IP>192.168.173.54</IP> </NIC> </HOST> <HOST> <NAME>drum</NAME> <DNSNAME>drum.somecorp.com</DNSNAME> <NIC>    <IP>192.168.172.47</IP> </NIC> </HOST> in this example the <HOST> and <IP> tags both have multiple entries.   the XMLDialog displays the host cod for both entries, and only 1 IP address, it would be nice to be able to address these in the read/write methods like: "HOST[0]:NIC:IP[1]","192.168.173.54" --Ben Burnett Sign In·View Thread·PermaLink Re: multiple entries of the same name mikeguz 18:47 14 Oct '05   I found the same problem, and believe it is related to this code in XmlStream.cpp: // if new parse cur position is in the last parser // last tag position we are done with the node char * curPos      = parserNode.getCurPos(); char * lastCurPos = parser.getLastTagPos(); if ( curPos >= lastCurPos ) {      break; } This code seems to assume that if you hit the end of a node at a certain level of XML heirarchy, you also must be done with that entire heirarchical level altogether. (When first </HOST> is hit, there won't be any more <HOST> entries to follow). I simply removed that code and allowed the above parser.parse() method to do what it does, and that seemed to fix the problem. I don't quite know if this will introduce other issues, though. - MikeG -- modified at 23:47 Friday 14th October, 2005 Sign In·View Thread·PermaLink Nodes have the same name BUG Ken Lee 21:43 9 Apr '03   I found a bug... when nearby nodes have the same name, the next node will be ignore ex: "n0"> "n1"> "e1"/> will only found the first node "n0" Sign In·View Thread·PermaLink 3.00/5 (2 votes) Re: Nodes have the same name BUG Ken Lee 21:52 9 Apr '03   sorry... example code here... <Node id="n0"> <Node id="n1"> <Element id="e1"/> </Node> </Node> Sign In·View Thread·PermaLink 4.00/5 (3 votes) pretty print of stream fazer77 19:00 7 Feb '03   in generell i find my way of prettyprinting a bit more easier to read: stringstream strm; strm             << "<Contacts>" << endl             << "<Contact/>" << endl             << initContact( "Joe Blow", 100 )             << initContact( "Mary Jane", 400, true, true )             << "</Contacts>" << endl ; another question: even its a examples, i find it better to return some string, which is streamed, instead to write directly to the stream. this method safes an unneccesary argument, can be reused easier, ok only disadvantage: creating temporarily a string for returning. but i think its ok, because the entries are all pretty small... --------------------- string initContact ( LPCTSTR cname, long id,                        bool hasAttributes = false,                        bool showToDo = false ) {       stringstream strm;      if ( hasAttributes )           strm << "<Contact language=\"english\" hasEmail=\"false\">" << endl;      else           strm << "<Contact>" << endl;       strm             << "<name>" << cname << "</name>" << endl             << "<id>" << id << "</id>" << endl       ;      if ( showToDo )      {             strm                   << "<ToDo>" << endl                   << "<Item></Item>" << endl                   << "<Item/>" << endl                   << "<Item>Call</Item>" << endl                   << "<Item>Say Hello</Item>" << endl                   << "<Item>Take Notes</Item>" << endl                   << "<Item>HangUp</Item>" << endl                   << "</ToDo>" << endl             ;      }      strm << "</Contact>" << endl;       return( strm.str() ); } Sign In·View Thread·PermaLink attributes fazer77 18:56 7 Feb '03   to be valid XML u should enclose all attribs with ": strm << "<Contact language=\"english\" hasEmail=\"false\">" << endl; cu george. Sign In·View Thread·PermaLink Bug fix for null nodes BenJeremy 11:06 2 Jan '03   Parser will 'kick out' of a parent node when a subnode is a null node entry: <Skin Name="CMX"> <Information>    <Author>John Doe</Author>    <Copyright>2003</Copyright> </Information> <Resource Type="Font" Name="SmallFont" File="Font10.fnt"/> <Resource Type="Font" Name="NormalFont" File="Font16.fnt"/> <Resource Type="Font" Name="GameText" File="GameText.fnt"/> <Resource Type="Image" Name="Title" File="TitleScr.jpg"/> <Resource Type="Image" Name="MenuBack" File="MenuScr.jpg"/> </Skin> This will kick out on the first "Resource" node. The problem lies in xmlparser.h, the routine 'parse()':           // if null tag no data or last tag           if ( hasNullTag() )           {                // update cur position                _current   = _firstTagEnd + idTagRightLength;                // done so show success                return true;           }          needs to change to:           // if null tag no data or last tag           if ( hasNullTag() )           {                // update cur position                _current   = _firstTagEnd + idTagRightLength;                _lastTagStart = _current;                _lastTagEnd   = _current;                // done so show success                return true;           }          and the parser will work properly. Sign In·View Thread·PermaLink 3.00/5 (1 vote) Re: Bug fix for null nodes BenJeremy 6:04 6 Jan '03   Strange... The fix does work, after a fashion, but there seems to be no rhyme or reason as to whether a null tag is considered a node or an element. I've modified my code not to worry about it, but if anybody can figure this out, I'd greatly appreciate it. Sign In·View Thread·PermaLink 2.00/5 (1 vote) Anoying bug for an xml parser yarp 21:42 21 Nov '02   I've got an xml file with standard header and comments like this: "1.0" ?> <!-- Ok ? --> <!-- Ok --> "0"> ... The parser fails reading the xml file because of the header and comments. Well, good job anyway. I'm working on the fix, I'll post it when done. Yarp http://www.senosoft.com/ Sign In·View Thread·PermaLink Re: Anoying bug for an xml parser yarp 22:17 21 Nov '02   So here'a partial fix: bool hasNullTag () { // get beginning of first tag char * firstTagBegin = _buffer + _firstTagStart; // get end of first tag char * firstTagEnd = _buffer + _firstTagEnd - 1; // if null tag marker if (( *firstTagBegin == '<' && *(firstTagBegin+1) == '?' ) || ( *firstTagBegin == '<' && *(firstTagBegin+1) == '!' ) || ( *firstTagEnd == '/' && *(firstTagEnd+1) == '>' )) return true; else return false; } Not perfect since the XmlNotify class is still called but this is easy to fix too: Each time a _subscriber is called just test if the parsed name isn't "?" or "!". I recall that the _subscriber is called by XmlStream to notify the caller for the xml parsing result. Yarp http://www.senosoft.com/ Sign In·View Thread·PermaLink Search David Frame 6:18 7 Feb '02   Is there a way to repetitively search the XML stream for any nodes containing specific elements, by value? This search would return the entire nodes contents. David Frame Sign In·View Thread·PermaLink 2.00/5 (1 vote) Re: Search ifgarcia 22:55 20 Apr '05   I would like to know if somebody has developped this issue. Thanks. Sign In·View Thread·PermaLink another bug in XmlParser.h Pika 0:47 28 Jul '01   File: XmlParser.h Method: bool parseAttributes () Change lines: if ( hasNullTag() ) _attrEnd -= -1; To these one: if ( hasNullTag() ) _attrEnd -= 1; Apllied to attributes in null-tag nodes. Sign In·View Thread·PermaLink notify on end-of-node? Chris Losinger 18:44 28 Mar '01   is there a way to force a notify callback when the end of a node is reached? this would make it much easier to handle nested nodes. -c ------------------------------ Smaller Animals Software, Inc. http://www.smalleranimals.com Sign In·View Thread·PermaLink 4.00/5 (1 vote) Re: notify on end-of-node? gok 18:11 17 Feb '03   I used extra parser's member _level for foundNode/foundElement notifications like those: // xml notify methods virtual void foundNode( string & name, string & attributes, int level ); virtual void foundElement( string & name, string & value, string & attributes, int level ); It is based on the fact that each parser instance is created for each node. xmlSteam.cpp: XmlParser parserNode(parser.getLevel()); if ( !parseNodes(parserNode,valueBuffer,valueLength) ) return false; xmlParser.h: XmlParser (int parentLevel) : _strParse() { clear(); // parser level, starts from 0 in default constructor _level = parentLevel + 1; } Gennady Khokhorin Software Developer Sign In·View Thread·PermaLink 2.00/5 (1 vote) Re: notify on end-of-node? khmerkidnow 14:50 29 Jul '04   Can you please send me the whole code. thanks Sign In·View Thread·PermaLink 2.00/5 (1 vote)

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