XMLElement.cc

Go to the documentation of this file.

#include "XMLElement.hh"
 
#include "ConfigException.hh"
#include "File.hh"
#include "FileContext.hh" // for bw compat
#include "FileException.hh"
#include "StringOp.hh"
#include "XMLException.hh"
#include "XMLOutputStream.hh"
#include "rapidsax.hh"
#include "serialize.hh"
#include "serialize_meta.hh"
#include "serialize_stl.hh"
 
#include <cassert>
#include <vector>
 
namespace openmsx {
 
// Returns nullptr when not found.
const XMLElement* XMLElement::findChild(std::string_view childName) const
{
        for (const auto* child = firstChild; child; child = child->nextSibling) {
                if (child->name == childName) {
                        return child;
                }
        }
        return nullptr;
}
 
// Similar to above, but instead of starting the search from the start of the
// list, start searching at 'hint'. This 'hint' parameter must be initialized
// with 'firstChild', on each successful search this parameter is updated to
// point to the next child (so that the next search starts from there). If the
// end of the list is reached we restart the search from the start (so that the
// full list is searched before giving up).
const XMLElement* XMLElement::findChild(std::string_view childName, const XMLElement*& hint) const
{
        for (const auto* current = hint; current; current = current->nextSibling) {
                if (current->name == childName) {
                        hint = current->nextSibling;
                        return current;
                }
        }
        for (const auto* current = firstChild; current != hint; current = current->nextSibling) {
                if (current->name == childName) {
                        hint = current->nextSibling;
                        return current;
                }
        }
        return nullptr;
}
 
// Like findChild(), but throws when not found.
const XMLElement& XMLElement::getChild(std::string_view childName) const
{
        if (const auto* elem = findChild(childName)) {
                return *elem;
        }
        throw ConfigException("Missing tag \"", childName, "\".");
}
 
// Throws when not found.
std::string_view XMLElement::getChildData(std::string_view childName) const
{
        return getChild(childName).getData();
}
 
// Returns default value when not found.
std::string_view XMLElement::getChildData(
        std::string_view childName, std::string_view defaultValue) const
{
        const auto* child = findChild(childName);
        return child ? child->getData() : defaultValue;
}
 
bool XMLElement::getChildDataAsBool(std::string_view childName, bool defaultValue) const
{
        const auto* child = findChild(childName);
        return child ? StringOp::stringToBool(child->getData()) : defaultValue;
}
 
int XMLElement::getChildDataAsInt(std::string_view childName, int defaultValue) const
{
        const auto* child = findChild(childName);
        if (!child) return defaultValue;
        return StringOp::stringTo<int>(child->getData()).value_or(defaultValue);
}
 
size_t XMLElement::numChildren() const
{
        return std::distance(getChildren().begin(), getChildren().end());
}
 
// Return nullptr when not found.
const XMLAttribute* XMLElement::findAttribute(std::string_view attrName) const
{
        for (const auto* attr = firstAttribute; attr; attr = attr->nextAttribute) {
                if (attr->getName() == attrName) {
                        return attr;
                }
        }
        return nullptr;
}
 
// Throws when not found.
const XMLAttribute& XMLElement::getAttribute(std::string_view attrName) const
{
        if (const auto* result = findAttribute(attrName)) {
                return *result;
        }
        throw ConfigException("Missing attribute \"", attrName, "\".");
}
 
// Throws when not found.
std::string_view XMLElement::getAttributeValue(std::string_view attrName) const
{
        return getAttribute(attrName).getValue();
}
 
std::string_view XMLElement::getAttributeValue(std::string_view attrName,
                                               std::string_view defaultValue) const
{
        const auto* attr = findAttribute(attrName);
        return attr ? attr->getValue() : defaultValue;
}
 
// Returns default value when not found.
bool XMLElement::getAttributeValueAsBool(std::string_view attrName,
                                         bool defaultValue) const
{
        const auto* attr = findAttribute(attrName);
        return attr ? StringOp::stringToBool(attr->getValue()) : defaultValue;
}
 
int XMLElement::getAttributeValueAsInt(std::string_view attrName,
                                       int defaultValue) const
{
        const auto* attr = findAttribute(attrName);
        if (!attr) return defaultValue;
        return StringOp::stringTo<int>(attr->getValue()).value_or(defaultValue);
}
 
// Like findAttribute(), but returns a pointer-to-the-XMLAttribute-pointer.
// This is mainly useful in combination with removeAttribute().
XMLAttribute** XMLElement::findAttributePointer(std::string_view attrName)
{
        for (auto** attr = &firstAttribute; *attr; attr = &(*attr)->nextAttribute) {
                if ((*attr)->getName() == attrName) {
                        return attr;
                }
        }
        return nullptr;
}
 
// Remove a specific attribute from the (single-linked) list.
void XMLElement::removeAttribute(XMLAttribute** attrPtr)
{
        auto* attr = *attrPtr;
        *attrPtr = attr->nextAttribute;
}
 
size_t XMLElement::numAttributes() const
{
        return std::distance(getAttributes().begin(), getAttributes().end());
}
 
 
// Search for child with given name, if it doesn't exist yet, then create it now
// with given data. Don't change the data of an already existing child.
XMLElement* XMLDocument::getOrCreateChild(XMLElement& parent, const char* childName, const char* childData)
{
        auto** elem = &parent.firstChild;
        while (true) {
                if (!*elem) {
                        auto* n = allocateElement(childName);
                        n->setData(childData);
                        *elem = n;
                        return n;
                }
                if ((*elem)->getName() == childName) {
                        return *elem;
                }
                elem = &(*elem)->nextSibling;
        }
}
 
// Search for child with given name, and change the data of that child. If the
// child didn't exist yet, then create it now (also with given data).
XMLElement* XMLDocument::setChildData(XMLElement& parent, const char* childName, const char* childData)
{
        auto** elem = &parent.firstChild;
        while (true) {
                if (!*elem) {
                        auto* n = allocateElement(childName);
                        *elem = n;
                        (*elem)->setData(childData);
                        return *elem;
                }
                if ((*elem)->getName() == childName) {
                        (*elem)->setData(childData);
                        return *elem;
                }
                elem = &(*elem)->nextSibling;
        }
}
 
// Set attribute to new value, if that attribute didn't exist yet, then also
// create it.
void XMLDocument::setAttribute(XMLElement& elem, const char* attrName, const char* attrValue)
{
        auto** attr = &elem.firstAttribute;
        while (true) {
                if (!*attr) {
                        auto* a = allocateAttribute(attrName, attrValue);
                        *attr = a;
                        return;
                }
                if ((*attr)->getName() == attrName) {
                        (*attr)->setValue(attrValue);
                        return;
                }
                attr = &(*attr)->nextAttribute;
        }
}
 
 
// Helper to parse a XML file into a XMLDocument.
class XMLDocumentHandler : public rapidsax::NullHandler
{
public:
        explicit XMLDocumentHandler(XMLDocument& doc_)
                : doc(doc_)
                , nextElement(&doc.root) {}
 
        [[nodiscard]] std::string_view getSystemID() const { return systemID; }
 
        void start(std::string_view name) {
                stack.push_back(currentElement);
 
                auto* n = doc.allocateElement(name.data());
                currentElement = n;
 
                assert(*nextElement == nullptr);
                *nextElement = n;
                nextElement = &n->firstChild;
 
                nextAttribute = &n->firstAttribute;
        }
 
        void stop() {
                nextElement = &currentElement->nextSibling;
                nextAttribute = nullptr;
                currentElement = stack.back();
                stack.pop_back();
        }
 
        void text(std::string_view text) {
                currentElement->data = text.data();
        }
 
        void attribute(std::string_view name, std::string_view value) {
                auto* a = doc.allocateAttribute(name.data(), value.data());
 
                assert(nextAttribute);
                assert(*nextAttribute == nullptr);
                *nextAttribute = a;
                nextAttribute = &a->nextAttribute;
        }
 
        void doctype(std::string_view txt) {
                auto pos1 = txt.find(" SYSTEM ");
                if (pos1 == std::string_view::npos) return;
                if ((pos1 + 8) >= txt.size()) return;
                char q = txt[pos1 + 8];
                if (q != one_of('"', '\'')) return;
                auto t = txt.substr(pos1 + 9);
                auto pos2 = t.find(q);
                if (pos2 == std::string_view::npos) return;
 
                systemID = t.substr(0, pos2);
        }
 
private:
        XMLDocument& doc;
 
        std::string_view systemID;
        std::vector<XMLElement*> stack;
        XMLElement* currentElement = nullptr;
        XMLElement** nextElement = nullptr;
        XMLAttribute** nextAttribute = nullptr;
};
 
XMLElement* XMLDocument::allocateElement(const char* name)
{
        void* p = allocator.allocate(sizeof(XMLElement), alignof(XMLElement));
        return new (p) XMLElement(name);
}
 
XMLElement* XMLDocument::allocateElement(const char* name, const char* data)
{
        void* p = allocator.allocate(sizeof(XMLElement), alignof(XMLElement));
        return new (p) XMLElement(name, data);
}
 
XMLAttribute* XMLDocument::allocateAttribute(const char* name, const char* value)
{
        void* p = allocator.allocate(sizeof(XMLAttribute), alignof(XMLAttribute));
        return new (p) XMLAttribute(name, value);
}
 
const char* XMLDocument::allocateString(std::string_view str)
{
        auto* p = static_cast<char*>(allocator.allocate(str.size() + 1, alignof(char)));
        auto e = ranges::copy(str, p);
        *e = '\0';
        return p;
}
 
void XMLDocument::load(const std::string& filename, std::string_view systemID)
{
        assert(!root);
 
        try {
                File file(filename);
                auto size = file.getSize();
                buf.resize(size + rapidsax::EXTRA_BUFFER_SPACE);
                file.read(std::span{buf.data(), size});
                buf[size] = 0;
        } catch (FileException& e) {
                throw XMLException(filename, ": failed to read: ", e.getMessage());
        }
 
        XMLDocumentHandler handler(*this);
        try {
                rapidsax::parse<rapidsax::zeroTerminateStrings>(handler, buf.data());
        } catch (rapidsax::ParseError& e) {
                throw XMLException(filename, ": Document parsing failed: ", e.what());
        }
        if (!root) {
                throw XMLException(filename,
                        ": Document doesn't contain mandatory root Element");
        }
        if (handler.getSystemID().empty()) {
                throw XMLException(filename, ": Missing systemID.\n"
                        "You're probably using an old incompatible file format.");
        }
        if (handler.getSystemID() != systemID) {
                throw XMLException(filename, ": systemID doesn't match "
                        "(expected ", systemID, ", got ", handler.getSystemID(), ")\n"
                        "You're probably using an old incompatible file format.");
        }
}
 
XMLElement* XMLDocument::loadElement(MemInputArchive& ar)
{
        auto name = ar.loadStr();
        if (name.empty()) return nullptr; // should only happen for empty document
        auto* elem = allocateElement(allocateString(name));
 
        unsigned numAttrs; ar.load(numAttrs);
        auto** attrPtr = &elem->firstAttribute;
        repeat(numAttrs, [&] {
                const char* n = allocateString(ar.loadStr());
                const char* v = allocateString(ar.loadStr());
                auto* attr = allocateAttribute(n, v);
                *attrPtr = attr;
                attrPtr = &attr->nextAttribute;
        });
 
        unsigned numElems; ar.load(numElems);
        if (numElems) {
                auto** elemPtr = &elem->firstChild;
                repeat(numElems, [&] {
                        auto* n = loadElement(ar);
                        *elemPtr = n;
                        elemPtr = &n->nextSibling;
                });
        } else {
                auto data = ar.loadStr();
                if (!data.empty()) {
                        elem->setData(allocateString(data));
                }
        }
 
        return elem;
}
 
void XMLDocument::serialize(MemInputArchive& ar, unsigned /*version*/)
{
        root = loadElement(ar);
}
 
static void saveElement(MemOutputArchive& ar, const XMLElement& elem)
{
        ar.save(elem.getName());
 
        ar.save(unsigned(elem.numAttributes()));
        for (const auto& attr : elem.getAttributes()) {
                ar.save(attr.getName());
                ar.save(attr.getValue());
        }
 
        auto numElems = unsigned(elem.numChildren());
        ar.save(numElems);
        if (numElems) {
                for (const auto& child : elem.getChildren()) {
                        saveElement(ar, child);
                }
        } else {
                ar.save(elem.getData());
        }
}
 
void XMLDocument::serialize(MemOutputArchive& ar, unsigned /*version*/) const
{
        if (root) {
                saveElement(ar, *root);
        } else {
                std::string_view empty;
                ar.save(empty);
        }
}
 
XMLElement* XMLDocument::clone(const XMLElement& inElem)
{
        auto* outElem = allocateElement(allocateString(inElem.getName()));
 
        auto** attrPtr = &outElem->firstAttribute;
        for (const auto& inAttr : inElem.getAttributes()) {
                const char* n = allocateString(inAttr.getName());
                const char* v = allocateString(inAttr.getValue());
                auto* outAttr = allocateAttribute(n, v);
                *attrPtr = outAttr;
                attrPtr = &outAttr->nextAttribute;
        }
 
        if (auto data = inElem.getData() ; !data.empty()) {
                outElem->setData(allocateString(data));
        }
 
        auto** childPtr = &outElem->firstChild;
        for (const auto& inChild : inElem.getChildren()) {
                auto* outChild = clone(inChild);
                *childPtr = outChild;
                childPtr = &outChild->nextSibling;
        }
 
        return outElem;
}
 
void XMLDocument::serialize(XmlInputArchive& ar, unsigned /*version*/)
{
        const auto* current = ar.currentElement();
        if (const auto* elem = current->getFirstChild()) {
                assert(elem->nextSibling == nullptr); // at most 1 child
                root = clone(*elem);
        }
}
 
static void saveElement(XMLOutputStream<XmlOutputArchive>& stream, const XMLElement& elem)
{
        stream.with_tag(elem.getName(), [&]{
                for (const auto& attr : elem.getAttributes()) {
                        stream.attribute(attr.getName(), attr.getValue());
                }
                if (elem.hasChildren()) {
                        for (const auto& child : elem.getChildren()) {
                                saveElement(stream, child);
                        }
                } else {
                        stream.data(elem.getData());
                }
        });
}
 
void XMLDocument::serialize(XmlOutputArchive& ar, unsigned /*version*/) const
{
        auto& stream = ar.getXMLOutputStream();
        if (root) {
                saveElement(stream, *root);
        }
}
 
XMLElement* XMLDocument::clone(const OldXMLElement& inElem)
{
        auto* outElem = allocateElement(allocateString(inElem.name));
 
        auto** attrPtr = &outElem->firstAttribute;
        for (const auto& [inName, inValue] : inElem.attributes) {
                const char* n = allocateString(inName);
                const char* v = allocateString(inValue);
                auto* outAttr = allocateAttribute(n, v);
                *attrPtr = outAttr;
                attrPtr = &outAttr->nextAttribute;
        }
 
        if (!inElem.data.empty()) {
                outElem->setData(allocateString(inElem.data));
        }
 
        auto** childPtr = &outElem->firstChild;
        for (const auto& inChild : inElem.children) {
                auto* outChild = clone(inChild);
                *childPtr = outChild;
                childPtr = &outChild->nextSibling;
        }
 
        return outElem;
}
 
void XMLDocument::load(const OldXMLElement& elem)
{
        root = clone(elem);
}
 
 
static std::unique_ptr<FileContext> lastSerializedFileContext;
std::unique_ptr<FileContext> OldXMLElement::getLastSerializedFileContext()
{
        return std::move(lastSerializedFileContext);
}
// version 1: initial version
// version 2: removed 'context' tag
//            also removed 'parent', but that was never serialized
//        2b: (no need to increase version) name and data members are
//            serialized as normal members instead of constructor parameters
//        2c: (no need to increase version) attributes were initially stored as
//            map<string, string>, later this was changed to
//            vector<pair<string, string>>. To keep bw-compat the serialize()
//            method converted between these two formats. Though (by luck) in
//            the XML output both data structures are serialized to the same
//            format, so we can drop this conversion step without breaking
//            bw-compat.
template<typename Archive>
void OldXMLElement::serialize(Archive& ar, unsigned version)
{
        assert(Archive::IS_LOADER);
        ar.serialize("name",       name,
                     "data",       data,
                     "attributes", attributes,
                     "children",   children);
 
        if (ar.versionBelow(version, 2)) {
                std::unique_ptr<FileContext> context;
                ar.serialize("context", context);
                if (context) {
                        lastSerializedFileContext = std::move(context);
                }
        }
}
INSTANTIATE_SERIALIZE_METHODS(OldXMLElement);
 
} // namespace openmsx