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LHEReader.cc

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#include <algorithm>
#include <iostream>
#include <sstream>
#include <fstream>
#include <cstring>
#include <string>
#include <vector>

#include <boost/bind.hpp>

#include <xercesc/sax2/Attributes.hpp>
#include <xercesc/dom/DOM.hpp>

#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include "FWCore/Utilities/interface/Exception.h"

#include "GeneratorInterface/LHEInterface/interface/LHEReader.h"
#include "GeneratorInterface/LHEInterface/interface/LHERunInfo.h"
#include "GeneratorInterface/LHEInterface/interface/LHEEvent.h"

#include "Utilities/StorageFactory/interface/IOTypes.h"
#include "Utilities/StorageFactory/interface/Storage.h"
#include "Utilities/StorageFactory/interface/StorageFactory.h"

#include "XMLUtils.h"

XERCES_CPP_NAMESPACE_USE

namespace lhef {

class LHEReader::Source {
    public:
        Source() {}
        virtual ~Source() {}
        virtual XMLDocument *createReader(XMLDocument::Handler &handler) = 0;
};

class LHEReader::FileSource : public LHEReader::Source {
    public:
        FileSource(const std::string &fileURL)
        {
                Storage *storage =
                        StorageFactory::get()->open(fileURL,
                                                    IOFlags::OpenRead);

                if (!storage)
                        throw cms::Exception("FileOpenError")
                                << "Could not open LHE file \""
                                << fileURL << "\" for reading"
                                << std::endl;

                fileStream.reset(new StorageWrap(storage));
        }

        ~FileSource() {}

        XMLDocument *createReader(XMLDocument::Handler &handler)
        { return new XMLDocument(fileStream, handler); }

    private:
        std::auto_ptr<StorageWrap>      fileStream;
};

class LHEReader::XMLHandler : public XMLDocument::Handler {
    public:
        XMLHandler() :
                impl(0), gotObject(kNone), mode(kNone),
                xmlHeader(0), headerOk(false) {}
        ~XMLHandler()
        { if (xmlHeader) xmlHeader->release(); }

        enum Object {
                kNone = 0,
                kHeader,
                kInit,
                kComment,
                kEvent
        };

    protected:
        void startElement(const XMLCh *const uri,
                          const XMLCh *const localname,
                          const XMLCh *const qname,
                          const Attributes &attributes);

        void endElement(const XMLCh *const uri,
                        const XMLCh *const localname,
                        const XMLCh *const qname);

        void characters(const XMLCh *const data, const unsigned int length);
        void comment(const XMLCh *const data, const unsigned int length);

    private:
        friend class LHEReader;

        DOMImplementation               *impl;
        std::string                     buffer;
        Object                          gotObject;
        Object                          mode;
        DOMDocument                     *xmlHeader;
        std::vector<DOMElement*>        xmlNodes;
        bool                            headerOk;
        std::vector<LHERunInfo::Header> headers;
};

static void attributesToDom(DOMElement *dom, const Attributes &attributes)
{
        for(unsigned int i = 0; i < attributes.getLength(); i++) {
                const XMLCh *name = attributes.getQName(i);
                const XMLCh *value = attributes.getValue(i);

                dom->setAttribute(name, value);
        }
}

static void fillHeader(LHERunInfo::Header &header, const char *data,
                       int len = -1)
{
        const char *end = len >= 0 ? (data + len) : 0;
        while(*data && (!end || data < end)) {
                std::size_t len = std::strcspn(data, "\r\n");
                if (end && data + len > end)
                        len = end - data;
                if (data[len] == '\r' && data[len + 1] == '\n')
                        len += 2;
                else if (data[len])
                        len++;
                header.addLine(std::string(data, len));
                data += len;
        }
}

void LHEReader::XMLHandler::startElement(const XMLCh *const uri,
                                         const XMLCh *const localname,
                                         const XMLCh *const qname,
                                         const Attributes &attributes)
{
        std::string name((const char*)XMLSimpleStr(qname));

        if (!headerOk) {
                if (name != "LesHouchesEvents")
                        throw cms::Exception("InvalidFormat")
                                << "LHE file has invalid header" << std::endl;
                headerOk = true;
                return;
        }

        if (mode == kHeader) {
                DOMElement *elem = xmlHeader->createElement(qname);
                attributesToDom(elem, attributes);
                xmlNodes.back()->appendChild(elem);
                xmlNodes.push_back(elem);
                return;
        } else if (mode != kNone)
                throw cms::Exception("InvalidFormat")
                        << "LHE file has invalid format" << std::endl;

        if (name == "header") {
                if (!impl)
                        impl = DOMImplementationRegistry::getDOMImplementation(
                                                        XMLUniStr("Core"));
                xmlHeader = impl->createDocument(0, qname, 0);
                xmlNodes.resize(1);
                xmlNodes[0] = xmlHeader->getDocumentElement();
                mode = kHeader;
        } if (name == "init")
                mode = kInit;
        else if (name == "event")
                mode = kEvent;

        if (mode == kNone)
                throw cms::Exception("InvalidFormat")
                        << "LHE file has invalid format" << std::endl;

        buffer.clear();
}

void LHEReader::XMLHandler::endElement(const XMLCh *const uri,
                                       const XMLCh *const localname,
                                       const XMLCh *const qname)
{
        if (mode) {
                if (mode == kHeader && xmlNodes.size() > 1) {
                        xmlNodes.resize(xmlNodes.size() - 1);
                        return;
                } else if (mode == kHeader) {
                        std::auto_ptr<DOMWriter> writer(
                                static_cast<DOMImplementationLS*>(
                                                impl)->createDOMWriter());
                        writer->setEncoding(XMLUniStr("UTF-8"));
                        XMLSimpleStr buffer(
                                        writer->writeToString(*xmlNodes[0]));
                        LHERunInfo::Header header("header");
                        const char *p =
                                std::strchr((const char*)buffer, '>') + 1;
                        const char *q = std::strrchr(p, '<');
                        fillHeader(header, p, q - p);
                        headers.push_back(header);

                        xmlHeader->release();
                        xmlHeader = 0;
                }

                if (gotObject != kNone)
                        throw cms::Exception("InvalidState")
                                << "Unexpected pileup in"
                                    " LHEReader::XMLHandler::endElement"
                                << std::endl;

                gotObject = mode;
                mode = kNone;
        }
}

void LHEReader::XMLHandler::characters(const XMLCh *const data_,
                                       const unsigned int length)
{
        if (mode == kHeader) {
                DOMText *text = xmlHeader->createTextNode(data_);
                xmlNodes.back()->appendChild(text);
                return;
        }

        if (XMLSimpleStr::isAllSpaces(data_, length))
                return;

        unsigned int offset = 0;
        while(offset < length && XMLSimpleStr::isSpace(data_[offset]))
                offset++;

        XMLSimpleStr data(data_ + offset);

        if (mode == kNone)
                throw cms::Exception("InvalidFormat")
                        << "LHE file has invalid format" << std::endl;

        buffer.append(data);
}

void LHEReader::XMLHandler::comment(const XMLCh *const data_,
                                    const unsigned int length)
{
        if (mode == kHeader) {
                DOMComment *comment = xmlHeader->createComment(data_);
                xmlNodes.back()->appendChild(comment);
                return;
        }

        XMLSimpleStr data(data_);

        LHERunInfo::Header header;
        fillHeader(header, data);
        headers.push_back(header);
}

LHEReader::LHEReader(const edm::ParameterSet &params) :
        fileURLs(params.getUntrackedParameter< std::vector<std::string> >("fileNames")),
        firstEvent(params.getUntrackedParameter<unsigned int>("seekEvent", 0)),
        maxEvents(params.getUntrackedParameter<int>("limitEvents", -1)),
        curIndex(0), handler(new XMLHandler())
{
}

LHEReader::LHEReader(const std::vector<std::string> &fileNames,
                     unsigned int firstEvent) :
        fileURLs(fileNames), firstEvent(firstEvent), maxEvents(-1),
        curIndex(0), handler(new XMLHandler())
{
}

LHEReader::~LHEReader()
{
}

boost::shared_ptr<LHEEvent> LHEReader::next()
{
        while(curDoc.get() || curIndex < fileURLs.size()) {
                if (!curDoc.get()) {
                        curSource.reset(new FileSource(fileURLs[curIndex++]));
                        curDoc.reset(curSource->createReader(*handler));
                        curRunInfo.reset();
                }

                XMLHandler::Object event = handler->gotObject;
                handler->gotObject = XMLHandler::kNone;

                std::istringstream data;
                if (event != XMLHandler::kNone) {
                        data.str(handler->buffer);
                        handler->buffer.clear();
                }

                switch(event) {
                    case XMLHandler::kNone:
                        if (!curDoc->parse())
                                curDoc.reset();
                        break;

                    case XMLHandler::kHeader:
                        break;

                    case XMLHandler::kInit:
                        curRunInfo.reset(new LHERunInfo(data));
                        std::for_each(handler->headers.begin(),
                                      handler->headers.end(),
                                      boost::bind(&LHERunInfo::addHeader,
                                                  curRunInfo.get(), _1));
                        handler->headers.clear();
                        break;

                    case XMLHandler::kComment:
                        break;

                    case XMLHandler::kEvent:
                        if (!curRunInfo.get())
                                throw cms::Exception("InvalidState")
                                        << "Got LHE event without"
                                           " initialization." << std::endl;

                        if (firstEvent > 0) {
                                firstEvent--;
                                continue;
                        }

                        if (maxEvents == 0)
                                return boost::shared_ptr<LHEEvent>();
                        else if (maxEvents > 0)
                                maxEvents--;

                        return boost::shared_ptr<LHEEvent>(
                                        new LHEEvent(curRunInfo, data));
                }
        }

        return boost::shared_ptr<LHEEvent>();
}

} // namespace lhef

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