Examples of net.sf.saxon.om.NamePool

net.sf.saxon.om.NamePool
A NamePool holds a collection of expanded names, each containing a namespace URI, a namespace prefix, and a local name; plus a collection of namespaces, each consisting of a prefix/URI pair.
Each expanded name is allocated a unique integer namecode. The namecode enables all three parts of the expanded name to be determined, that is, the prefix, the URI, and the local name.

The equivalence betweem names depends only on the URI and the local name. The namecode is designed so that if two namecodes represent names with the same URI and local name, the two namecodes are the same in the bottom 20 bits. It is therefore possible to compare two names for equivalence by performing an integer comparison of these 20 bits. The bottom 20 bits of a namecode are referred to as a fingerprint.

The NamePool eliminates duplicate names if they have the same prefix, uri, and local part. It retains duplicates if they have different prefixes

Internally the NamePool is organized as a fixed number of hash chains. The selection of a hash chain is based on hashing the local name, because it is unusual to have many names that share the same local name but use different URIs. There are 1024 hash chains and the identifier of the hash chain forms the bottom ten bits of the namecode. The next ten bits represent the sequential position of an entry within the hash chain. The upper bits represent the selection of prefix, from among the list of prefixes that have been used with a given URI. A prefix part of zero means no prefix; if the two prefixes used with a particular namespace are "xs" and "xsd", say, then these will be prefix codes 1 and 2.

Fingerprints in the range 0 to 1023 are reserved for system use, and are allocated as constants mainly to names in the XSLT and XML Schema namespaces: constants representing these names are found in {@link StandardNames}.
Operations that update the NamePool, or that have the potential to update it, are synchronized. Read-only operations are done without synchronization. Although technically unsafe, this has not led to any problems in practice. Performance problems due to excessive contention on the NamePool have occasionally been observed: if this happens, the best strategy is to consider splitting the workload to use multiple Configurations each with a separate NamePool.

Internal organization of the NamePool

The NamePool holds two kinds of entry: name entries, representing expanded names (local name + prefix + URI), identified by a name code, and namespace entries (prefix + URI) identified by a namespace code.

The data structure of the name table is as follows.

There is a fixed size hash table; names are allocated to slots in this table by hashing on the local name. Each entry in the table is the head of a chain of NameEntry objects representing names that have the same hash code.

Each NameEntry represents a distinct name (same URI and local name). It contains the local name as a string, plus a short integer representing the URI (as an offset into the array uris[] - this is known as the URIcode).

The fingerprint of a name consists of the hash slot number (in the bottom 10 bits) concatenated with the depth of the entry down the chain of hash synonyms (in the next 10 bits). Fingerprints with depth 0 (i.e., in the range 0-1023) are reserved for predefined names (names of XSLT elements and attributes, and of built-in types). These names are not stored in the name pool, but are accessible as if they were.

A nameCode contains the fingerprint in the bottom 20 bits. It also contains a 10-bit prefix index. This distinguishes the prefix used, among all the prefixes that have been used with this namespace URI. If the prefix index is zero, the prefix is null. Otherwise, it indexes an array of prefix Strings associated with the namespace URI. Note that the data structures and algorithms are optimized for the case where URIs usually use the same prefix.

The nameCode -1 is reserved to mean "not known" or inapplicable. The fingerprint -1 has the same meaning. Note that masking the nameCode -1 to extract its bottom 20 bits is incorrect, and will lead to errors.
@author Michael H. Kay

    // For background see net.sf.saxon.om.NamespaceIterator and
    // net.sf.saxon.om.NamespaceDeclarationsImpl
    int[] namespaces = node.getDeclaredNamespaces(NodeInfo.EMPTY_NAMESPACE_LIST);
    int i = 0;
    int nsCode;
    NamePool pool = null;
    while (i < namespaces.length && (nsCode = namespaces[i]) != -1) {
      short uriCode = (short) (nsCode & 0xffff);
      if (uriCode != 0) { // it is not an undeclaration
        if (pool == null) pool = node.getNamePool();
        String uri = pool.getURIFromURICode(uriCode);
        String prefix = pool.getPrefixFromNamespaceCode(nsCode);
        
        if (prefixes != null && prefixes.contains(prefix)) {
          if (DEBUG) System.err.println(
            "Safely ignoring additional namespace declaration for prefix=" 
            + prefix + ", uri=" + uri);

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  private static Configuration createConfiguration() {
    Configuration config = new Configuration(); 
    config.setHostLanguage(Configuration.XQUERY);
    config.setErrorListener(new DefaultErrorListener());
    config.setAllowExternalFunctions(ALLOW_EXTERNAL_FUNCTIONS);
    if (!SHARE_NAMEPOOLS) config.setNamePool(new NamePool());
//    config.setAllNodesUntyped(true);
//    config.setLazyConstructionMode(true);
//    config.setModuleURIResolver(new DefaultModuleURIResolver());
    
    if (TRACE) {

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            return this;
        }
        if (namespaceCodes == null || namespaceCodes.length == 0) {
            return this;
        }
        NamePool pool = visitor.getExecutable().getConfiguration().getNamePool();
        int uriCode = getURICode(pool);
        if (content instanceof FixedElement) {
            if (((FixedElement)content).getURICode(pool) == uriCode) {
                ((FixedElement)content).removeRedundantNamespaces(visitor, namespaceCodes);
            }

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        int att = fat.getAttributeNameCode() & NamePool.FP_MASK;
        if (att == StandardNames.XSI_TYPE) {
            Expression attValue = fat.getSelect();
            if (attValue instanceof StringLiteral) {
                try {
                    NamePool pool = env.getNamePool();
                    String[] parts = env.getConfiguration().getNameChecker().getQNameParts(
                            ((StringLiteral)attValue).getStringValue());
                    // The only namespace bindings we can trust are those declared on this element
                    // We could also trust those on enclosing LREs in the same function/template,
                    // but it's not a big win to go looking for them.
                    int uriCode = -1;
                    for (int n=0; n<namespaceCodes.length; n++) {
                        String prefix = pool.getPrefixFromNamespaceCode(namespaceCodes[n]);
                        if (prefix.equals(parts[0])) {
                            uriCode = namespaceCodes[n] & 0xffff;
                            break;
                        }
                    }
                    if (uriCode == -1) {
                        return null;
                    }
                    String uri = pool.getURIFromURICode((short)uriCode);
                    int typefp = pool.allocate(parts[0], uri, parts[1]) & NamePool.FP_MASK;
                    return env.getConfiguration().getSchemaType(typefp);
                } catch (QNameException e) {
                    throw new XPathException(e.getMessage());
                }
            }

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     *          if the module cannot be located, and if delegation to the default
     *          module resolver is not required.
     */


    public StreamSource[] resolve(String moduleURI, String baseURI, String[] locations) throws XPathException {
        NamePool pool = testCase.getNamePool();
        int moduleNC = pool.allocate("", "http://www.w3.org/2005/02/query-test-XQTSCatalog", "module");
        int namespaceNC = pool.allocate("", "", "namespace");
        AxisIterator iter = testCase.iterateAxis(Axis.CHILD, new NameTest(Type.ELEMENT, moduleNC, pool));
        List catalogLocations = new ArrayList(5);
        while (true) {
            NodeInfo m = (NodeInfo)iter.next();
            if (m == null) break;

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                throw new XQException("Wrong node kind for getNodeName()");
            }
            IntHashSet set = ((NodeTest)type).getRequiredNodeNames();
            if (set != null && set.size() == 1) {
                int fp = set.getFirst(-1);
                NamePool pool = config.getNamePool();
                String uri = pool.getURI(fp);
                String local = pool.getLocalName(fp);
                return new QName(uri, local);
            } else {
                return null;
            }
        }

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        throw new XQException("getNodeName() is not defined for this kind of item type");
    }


    public String getPIName() throws XQException {
        if (itemType instanceof NameTest && itemType.getPrimitiveType() == Type.PROCESSING_INSTRUCTION) {
            NamePool pool = config.getNamePool();
            return pool.getLocalName(((NameTest)itemType).getFingerprint());
        } else if (itemType instanceof NodeKindTest && itemType.getPrimitiveType() == Type.PROCESSING_INSTRUCTION) {
            return null;
        } else {
            throw new XQException("Item kind is not a processing instruction");
        }

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    public QName getTypeName() throws XQException {
        ItemType type = itemType;
        if (type instanceof AtomicType) {
            int fp = ((AtomicType)type).getFingerprint();
            NamePool pool = config.getNamePool();
            String uri = pool.getURI(fp);
            String local = pool.getLocalName(fp);
            return new QName(uri, local);
        }
        if (type instanceof DocumentNodeTest) {
            type = ((DocumentNodeTest)type).getElementTest();
        }
        if (type instanceof NodeTest) {
            if ((((NodeTest)type).getNodeKindMask() &
                    (1<<Type.DOCUMENT | 1<<Type.TEXT | 1<<Type.COMMENT | 1<<Type.PROCESSING_INSTRUCTION | 1<<Type.NAMESPACE)) != 0) {
                throw new XQException("getTypeName() failed: itemType is not a document, element, or attribute test");
            }
            SchemaType t = ((NodeTest)type).getContentType();
            if (t != null) {
                int fp = ((NodeTest)type).getContentType().getFingerprint();
                NamePool pool = config.getNamePool();
                String uri = pool.getURI(fp);
                String local = pool.getLocalName(fp);
                return new QName(uri, local);
            }
        }
        throw new XQException("getTypeName() failed: itemType is not a document, element, or attribute test");
    }

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     * Type-check the expression
     */


    public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException {


        NamePool namePool = visitor.getConfiguration().getNamePool();
        TypeHierarchy th = visitor.getConfiguration().getTypeHierarchy();
        StaticContext env = visitor.getStaticContext();


        operand0 = visitor.typeCheck(operand0, contextItemType);
        if (Literal.isEmptySequence(operand0)) {

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        }
        String uri = elparts2[0];
        String local = elparts2[1];
        String prefix = NameChecker.getPrefix(elparts2[2]);


        NamePool namePool = config.getNamePool();
        int nameCode = namePool.allocate(prefix, uri, local);


        receiver.startElement(nameCode, StandardNames.XS_UNTYPED, 0, 0);
        for (Iterator<String> iter = nsDeclarations.keySet().iterator(); iter.hasNext();) {
            String nsprefix = iter.next();
            String nsuri = nsDeclarations.get(nsprefix);
            receiver.namespace(namePool.allocateNamespaceCode(nsprefix, nsuri), 0);
        }


        if (atts != null) {
            final int len = atts.getLength();
            for (int a2=0; a2<len; a2++) {
                Attr att = (Attr)atts.item(a2);
                String attname = att.getName();
                if (attname.startsWith("xmlns") && (attname.equals("xmlns") || attname.startsWith("xmlns:"))) {
                    // do nothing
                } else {
                    //System.err.println("Processing attribute " + attname);
                    String[] parts2 = nsSupport.processName(attname, parts, true);
                    if (parts2==null) {
                          throw new XPathException("Undeclared namespace in " + attname);
                    }
                    String atturi = parts2[0];
                    String attlocal = parts2[1];
                    String attprefix = NameChecker.getPrefix(parts2[2]);


                    // Note, DOM gives no guarantee that the prefix and URI are actually consistent. For example,
                    // it's possible programmatically to construct attribute nodes that have a namespace URI but
                    // no prefix. We don't attempt to deal with such situations: garbage in, garbage out.


                    int attCode = namePool.allocate(attprefix, atturi, attlocal);


                    receiver.attribute(attCode, StandardNames.XS_UNTYPED_ATOMIC, att.getValue(), 0, 0);
                }
            }
        }

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net.sf.saxon.event.NamespaceReducer

net.sf.saxon.event.ResultWrapper

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Examples of net.sf.saxon.om.NamePool

Internal organization of the NamePool

Related Classes of net.sf.saxon.om.NamePool