| // NamespaceSupport.java - generic Namespace support for SAX. |
| // Written by David Megginson, sax@megginson.com |
| // This class is in the Public Domain. NO WARRANTY! |
| |
| // $Id: NamespaceSupport.java,v 1.8 2000/05/05 17:49:53 david Exp $ |
| |
| package org.xml.sax.helpers; |
| |
| import java.util.EmptyStackException; |
| import java.util.Enumeration; |
| import java.util.Hashtable; |
| import java.util.Vector; |
| |
| |
| /** |
| * Encapsulate Namespace logic for use by SAX drivers. |
| * |
| * <blockquote> |
| * <em>This module, both source code and documentation, is in the |
| * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em> |
| * </blockquote> |
| * |
| * <p>This class encapsulates the logic of Namespace processing: |
| * it tracks the declarations currently in force for each context |
| * and automatically processes qualified XML 1.0 names into their |
| * Namespace parts; it can also be used in reverse for generating |
| * XML 1.0 from Namespaces.</p> |
| * |
| * <p>Namespace support objects are reusable, but the reset method |
| * must be invoked between each session.</p> |
| * |
| * <p>Here is a simple session:</p> |
| * |
| * <pre> |
| * String parts[] = new String[3]; |
| * NamespaceSupport support = new NamespaceSupport(); |
| * |
| * support.pushContext(); |
| * support.declarePrefix("", "http://www.w3.org/1999/xhtml"); |
| * support.declarePrefix("dc", "http://www.purl.org/dc#"); |
| * |
| * String parts[] = support.processName("p", parts, false); |
| * System.out.println("Namespace URI: " + parts[0]); |
| * System.out.println("Local name: " + parts[1]); |
| * System.out.println("Raw name: " + parts[2]); |
| |
| * String parts[] = support.processName("dc:title", parts, false); |
| * System.out.println("Namespace URI: " + parts[0]); |
| * System.out.println("Local name: " + parts[1]); |
| * System.out.println("Raw name: " + parts[2]); |
| |
| * support.popContext(); |
| * </pre> |
| * |
| * <p>Note that this class is optimized for the use case where most |
| * elements do not contain Namespace declarations: if the same |
| * prefix/URI mapping is repeated for each context (for example), this |
| * class will be somewhat less efficient.</p> |
| * |
| * @since SAX 2.0 |
| * @author David Megginson, |
| * <a href="mailto:sax@megginson.com">sax@megginson.com</a> |
| * @version 2.0 |
| */ |
| public class NamespaceSupport |
| { |
| |
| |
| //////////////////////////////////////////////////////////////////// |
| // Constants. |
| //////////////////////////////////////////////////////////////////// |
| |
| |
| /** |
| * The XML Namespace as a constant. |
| * |
| * <p>This is the Namespace URI that is automatically mapped |
| * to the "xml" prefix.</p> |
| */ |
| public final static String XMLNS = |
| "http://www.w3.org/XML/1998/namespace"; |
| |
| |
| /** |
| * An empty enumeration. |
| */ |
| private final static Enumeration EMPTY_ENUMERATION = |
| new Vector().elements(); |
| |
| |
| //////////////////////////////////////////////////////////////////// |
| // Constructor. |
| //////////////////////////////////////////////////////////////////// |
| |
| |
| /** |
| * Create a new Namespace support object. |
| */ |
| public NamespaceSupport () |
| { |
| reset(); |
| } |
| |
| |
| |
| //////////////////////////////////////////////////////////////////// |
| // Context management. |
| //////////////////////////////////////////////////////////////////// |
| |
| |
| /** |
| * Reset this Namespace support object for reuse. |
| * |
| * <p>It is necessary to invoke this method before reusing the |
| * Namespace support object for a new session.</p> |
| */ |
| public void reset () |
| { |
| contexts = new Context[32]; |
| contextPos = 0; |
| contexts[contextPos] = currentContext = new Context(); |
| currentContext.declarePrefix("xml", XMLNS); |
| } |
| |
| |
| /** |
| * Start a new Namespace context. |
| * |
| * <p>Normally, you should push a new context at the beginning |
| * of each XML element: the new context will automatically inherit |
| * the declarations of its parent context, but it will also keep |
| * track of which declarations were made within this context.</p> |
| * |
| * <p>The Namespace support object always starts with a base context |
| * already in force: in this context, only the "xml" prefix is |
| * declared.</p> |
| * |
| * @see #popContext |
| */ |
| public void pushContext () |
| { |
| int max = contexts.length; |
| contextPos++; |
| |
| // Extend the array if necessary |
| if (contextPos >= max) { |
| Context newContexts[] = new Context[max*2]; |
| System.arraycopy(contexts, 0, newContexts, 0, max); |
| max *= 2; |
| contexts = newContexts; |
| } |
| |
| // Allocate the context if necessary. |
| currentContext = contexts[contextPos]; |
| if (currentContext == null) { |
| contexts[contextPos] = currentContext = new Context(); |
| } |
| |
| // Set the parent, if any. |
| if (contextPos > 0) { |
| currentContext.setParent(contexts[contextPos - 1]); |
| } |
| } |
| |
| |
| /** |
| * Revert to the previous Namespace context. |
| * |
| * <p>Normally, you should pop the context at the end of each |
| * XML element. After popping the context, all Namespace prefix |
| * mappings that were previously in force are restored.</p> |
| * |
| * <p>You must not attempt to declare additional Namespace |
| * prefixes after popping a context, unless you push another |
| * context first.</p> |
| * |
| * @see #pushContext |
| */ |
| public void popContext () |
| { |
| contextPos--; |
| if (contextPos < 0) { |
| throw new EmptyStackException(); |
| } |
| currentContext = contexts[contextPos]; |
| } |
| |
| |
| |
| //////////////////////////////////////////////////////////////////// |
| // Operations within a context. |
| //////////////////////////////////////////////////////////////////// |
| |
| |
| /** |
| * Declare a Namespace prefix. |
| * |
| * <p>This method declares a prefix in the current Namespace |
| * context; the prefix will remain in force until this context |
| * is popped, unless it is shadowed in a descendant context.</p> |
| * |
| * <p>To declare a default Namespace, use the empty string. The |
| * prefix must not be "xml" or "xmlns".</p> |
| * |
| * <p>Note that you must <em>not</em> declare a prefix after |
| * you've pushed and popped another Namespace.</p> |
| * |
| * <p>Note that there is an asymmetry in this library: while {@link |
| * #getPrefix getPrefix} will not return the default "" prefix, |
| * even if you have declared one; to check for a default prefix, |
| * you have to look it up explicitly using {@link #getURI getURI}. |
| * This asymmetry exists to make it easier to look up prefixes |
| * for attribute names, where the default prefix is not allowed.</p> |
| * |
| * @param prefix The prefix to declare, or null for the empty |
| * string. |
| * @param uri The Namespace URI to associate with the prefix. |
| * @return true if the prefix was legal, false otherwise |
| * @see #processName |
| * @see #getURI |
| * @see #getPrefix |
| */ |
| public boolean declarePrefix (String prefix, String uri) |
| { |
| if (prefix.equals("xml") || prefix.equals("xmlns")) { |
| return false; |
| } else { |
| currentContext.declarePrefix(prefix, uri); |
| return true; |
| } |
| } |
| |
| |
| /** |
| * Process a raw XML 1.0 name. |
| * |
| * <p>This method processes a raw XML 1.0 name in the current |
| * context by removing the prefix and looking it up among the |
| * prefixes currently declared. The return value will be the |
| * array supplied by the caller, filled in as follows:</p> |
| * |
| * <dl> |
| * <dt>parts[0]</dt> |
| * <dd>The Namespace URI, or an empty string if none is |
| * in use.</dd> |
| * <dt>parts[1]</dt> |
| * <dd>The local name (without prefix).</dd> |
| * <dt>parts[2]</dt> |
| * <dd>The original raw name.</dd> |
| * </dl> |
| * |
| * <p>All of the strings in the array will be internalized. If |
| * the raw name has a prefix that has not been declared, then |
| * the return value will be null.</p> |
| * |
| * <p>Note that attribute names are processed differently than |
| * element names: an unprefixed element name will received the |
| * default Namespace (if any), while an unprefixed element name |
| * will not.</p> |
| * |
| * @param qName The raw XML 1.0 name to be processed. |
| * @param parts An array supplied by the caller, capable of |
| * holding at least three members. |
| * @param isAttribute A flag indicating whether this is an |
| * attribute name (true) or an element name (false). |
| * @return The supplied array holding three internalized strings |
| * representing the Namespace URI (or empty string), the |
| * local name, and the raw XML 1.0 name; or null if there |
| * is an undeclared prefix. |
| * @see #declarePrefix |
| * @see java.lang.String#intern */ |
| public String [] processName (String qName, String parts[], |
| boolean isAttribute) |
| { |
| String myParts[] = currentContext.processName(qName, isAttribute); |
| if (myParts == null) { |
| return null; |
| } else { |
| parts[0] = myParts[0]; |
| parts[1] = myParts[1]; |
| parts[2] = myParts[2]; |
| return parts; |
| } |
| } |
| |
| |
| /** |
| * Look up a prefix and get the currently-mapped Namespace URI. |
| * |
| * <p>This method looks up the prefix in the current context. |
| * Use the empty string ("") for the default Namespace.</p> |
| * |
| * @param prefix The prefix to look up. |
| * @return The associated Namespace URI, or null if the prefix |
| * is undeclared in this context. |
| * @see #getPrefix |
| * @see #getPrefixes |
| */ |
| public String getURI (String prefix) |
| { |
| return currentContext.getURI(prefix); |
| } |
| |
| |
| /** |
| * Return an enumeration of all prefixes currently declared. |
| * |
| * <p><strong>Note:</strong> if there is a default prefix, it will not be |
| * returned in this enumeration; check for the default prefix |
| * using the {@link #getURI getURI} with an argument of "".</p> |
| * |
| * @return An enumeration of all prefixes declared in the |
| * current context except for the empty (default) |
| * prefix. |
| * @see #getDeclaredPrefixes |
| * @see #getURI |
| */ |
| public Enumeration getPrefixes () |
| { |
| return currentContext.getPrefixes(); |
| } |
| |
| |
| /** |
| * Return one of the prefixes mapped to a Namespace URI. |
| * |
| * <p>If more than one prefix is currently mapped to the same |
| * URI, this method will make an arbitrary selection; if you |
| * want all of the prefixes, use the {@link #getPrefixes} |
| * method instead.</p> |
| * |
| * <p><strong>Note:</strong> this will never return the empty (default) prefix; |
| * to check for a default prefix, use the {@link #getURI getURI} |
| * method with an argument of "".</p> |
| * |
| * @param uri The Namespace URI. |
| * @param isAttribute true if this prefix is for an attribute |
| * (and the default Namespace is not allowed). |
| * @return One of the prefixes currently mapped to the URI supplied, |
| * or null if none is mapped or if the URI is assigned to |
| * the default Namespace. |
| * @see #getPrefixes(java.lang.String) |
| * @see #getURI |
| */ |
| public String getPrefix (String uri) |
| { |
| return currentContext.getPrefix(uri); |
| } |
| |
| |
| /** |
| * Return an enumeration of all prefixes currently declared for a URI. |
| * |
| * <p>This method returns prefixes mapped to a specific Namespace |
| * URI. The xml: prefix will be included. If you want only one |
| * prefix that's mapped to the Namespace URI, and you don't care |
| * which one you get, use the {@link #getPrefix getPrefix} |
| * method instead.</p> |
| * |
| * <p><strong>Note:</strong> the empty (default) prefix is <em>never</em> included |
| * in this enumeration; to check for the presence of a default |
| * Namespace, use the {@link #getURI getURI} method with an |
| * argument of "".</p> |
| * |
| * @param uri The Namespace URI. |
| * @return An enumeration of all prefixes declared in the |
| * current context. |
| * @see #getPrefix |
| * @see #getDeclaredPrefixes |
| * @see #getURI |
| */ |
| public Enumeration getPrefixes (String uri) |
| { |
| Vector prefixes = new Vector(); |
| Enumeration allPrefixes = getPrefixes(); |
| while (allPrefixes.hasMoreElements()) { |
| String prefix = (String)allPrefixes.nextElement(); |
| if (uri.equals(getURI(prefix))) { |
| prefixes.addElement(prefix); |
| } |
| } |
| return prefixes.elements(); |
| } |
| |
| |
| /** |
| * Return an enumeration of all prefixes declared in this context. |
| * |
| * <p>The empty (default) prefix will be included in this |
| * enumeration; note that this behaviour differs from that of |
| * {@link #getPrefix} and {@link #getPrefixes}.</p> |
| * |
| * @return An enumeration of all prefixes declared in this |
| * context. |
| * @see #getPrefixes |
| * @see #getURI |
| */ |
| public Enumeration getDeclaredPrefixes () |
| { |
| return currentContext.getDeclaredPrefixes(); |
| } |
| |
| |
| |
| //////////////////////////////////////////////////////////////////// |
| // Internal state. |
| //////////////////////////////////////////////////////////////////// |
| |
| private Context contexts[]; |
| private Context currentContext; |
| private int contextPos; |
| |
| |
| |
| //////////////////////////////////////////////////////////////////// |
| // Internal classes. |
| //////////////////////////////////////////////////////////////////// |
| |
| /** |
| * Internal class for a single Namespace context. |
| * |
| * <p>This module caches and reuses Namespace contexts, so the number allocated |
| * will be equal to the element depth of the document, not to the total |
| * number of elements (i.e. 5-10 rather than tens of thousands).</p> |
| */ |
| final class Context { |
| |
| /** |
| * Create the root-level Namespace context. |
| */ |
| Context () |
| { |
| copyTables(); |
| } |
| |
| |
| /** |
| * (Re)set the parent of this Namespace context. |
| * |
| * @param context The parent Namespace context object. |
| */ |
| void setParent (Context parent) |
| { |
| this.parent = parent; |
| declarations = null; |
| prefixTable = parent.prefixTable; |
| uriTable = parent.uriTable; |
| elementNameTable = parent.elementNameTable; |
| attributeNameTable = parent.attributeNameTable; |
| defaultNS = parent.defaultNS; |
| tablesDirty = false; |
| } |
| |
| |
| /** |
| * Declare a Namespace prefix for this context. |
| * |
| * @param prefix The prefix to declare. |
| * @param uri The associated Namespace URI. |
| * @see org.xml.sax.helpers.NamespaceSupport#declarePrefix |
| */ |
| void declarePrefix (String prefix, String uri) |
| { |
| // Lazy processing... |
| if (!tablesDirty) { |
| copyTables(); |
| } |
| if (declarations == null) { |
| declarations = new Vector(); |
| } |
| |
| prefix = prefix.intern(); |
| uri = uri.intern(); |
| if ("".equals(prefix)) { |
| if ("".equals(uri)) { |
| defaultNS = null; |
| } else { |
| defaultNS = uri; |
| } |
| } else { |
| prefixTable.put(prefix, uri); |
| uriTable.put(uri, prefix); // may wipe out another prefix |
| } |
| declarations.addElement(prefix); |
| } |
| |
| |
| /** |
| * Process a raw XML 1.0 name in this context. |
| * |
| * @param qName The raw XML 1.0 name. |
| * @param isAttribute true if this is an attribute name. |
| * @return An array of three strings containing the |
| * URI part (or empty string), the local part, |
| * and the raw name, all internalized, or null |
| * if there is an undeclared prefix. |
| * @see org.xml.sax.helpers.NamespaceSupport#processName |
| */ |
| String [] processName (String qName, boolean isAttribute) |
| { |
| String name[]; |
| Hashtable table; |
| |
| // Select the appropriate table. |
| if (isAttribute) { |
| table = elementNameTable; |
| } else { |
| table = attributeNameTable; |
| } |
| |
| // Start by looking in the cache, and |
| // return immediately if the name |
| // is already known in this content |
| name = (String[])table.get(qName); |
| if (name != null) { |
| return name; |
| } |
| |
| // We haven't seen this name in this |
| // context before. |
| name = new String[3]; |
| int index = qName.indexOf(':'); |
| |
| |
| // No prefix. |
| if (index == -1) { |
| if (isAttribute || defaultNS == null) { |
| name[0] = ""; |
| } else { |
| name[0] = defaultNS; |
| } |
| name[1] = qName.intern(); |
| name[2] = name[1]; |
| } |
| |
| // Prefix |
| else { |
| String prefix = qName.substring(0, index); |
| String local = qName.substring(index+1); |
| String uri; |
| if ("".equals(prefix)) { |
| uri = defaultNS; |
| } else { |
| uri = (String)prefixTable.get(prefix); |
| } |
| if (uri == null) { |
| return null; |
| } |
| name[0] = uri; |
| name[1] = local.intern(); |
| name[2] = qName.intern(); |
| } |
| |
| // Save in the cache for future use. |
| table.put(name[2], name); |
| tablesDirty = true; |
| return name; |
| } |
| |
| |
| /** |
| * Look up the URI associated with a prefix in this context. |
| * |
| * @param prefix The prefix to look up. |
| * @return The associated Namespace URI, or null if none is |
| * declared. |
| * @see org.xml.sax.helpers.NamespaceSupport#getURI |
| */ |
| String getURI (String prefix) |
| { |
| if ("".equals(prefix)) { |
| return defaultNS; |
| } else if (prefixTable == null) { |
| return null; |
| } else { |
| return (String)prefixTable.get(prefix); |
| } |
| } |
| |
| |
| /** |
| * Look up one of the prefixes associated with a URI in this context. |
| * |
| * <p>Since many prefixes may be mapped to the same URI, |
| * the return value may be unreliable.</p> |
| * |
| * @param uri The URI to look up. |
| * @return The associated prefix, or null if none is declared. |
| * @see org.xml.sax.helpers.NamespaceSupport#getPrefix |
| */ |
| String getPrefix (String uri) |
| { |
| if (uriTable == null) { |
| return null; |
| } else { |
| return (String)uriTable.get(uri); |
| } |
| } |
| |
| |
| /** |
| * Return an enumeration of prefixes declared in this context. |
| * |
| * @return An enumeration of prefixes (possibly empty). |
| * @see org.xml.sax.helpers.NamespaceSupport#getDeclaredPrefixes |
| */ |
| Enumeration getDeclaredPrefixes () |
| { |
| if (declarations == null) { |
| return EMPTY_ENUMERATION; |
| } else { |
| return declarations.elements(); |
| } |
| } |
| |
| |
| /** |
| * Return an enumeration of all prefixes currently in force. |
| * |
| * <p>The default prefix, if in force, is <em>not</em> |
| * returned, and will have to be checked for separately.</p> |
| * |
| * @return An enumeration of prefixes (never empty). |
| * @see org.xml.sax.helpers.NamespaceSupport#getPrefixes |
| */ |
| Enumeration getPrefixes () |
| { |
| if (prefixTable == null) { |
| return EMPTY_ENUMERATION; |
| } else { |
| return prefixTable.keys(); |
| } |
| } |
| |
| |
| |
| //////////////////////////////////////////////////////////////// |
| // Internal methods. |
| //////////////////////////////////////////////////////////////// |
| |
| |
| /** |
| * Copy on write for the internal tables in this context. |
| * |
| * <p>This class is optimized for the normal case where most |
| * elements do not contain Namespace declarations.</p> |
| */ |
| private void copyTables () |
| { |
| if (prefixTable != null) { |
| prefixTable = (Hashtable)prefixTable.clone(); |
| } else { |
| prefixTable = new Hashtable(); |
| } |
| if (uriTable != null) { |
| uriTable = (Hashtable)uriTable.clone(); |
| } else { |
| uriTable = new Hashtable(); |
| } |
| elementNameTable = new Hashtable(); |
| attributeNameTable = new Hashtable(); |
| tablesDirty = true; |
| } |
| |
| |
| |
| //////////////////////////////////////////////////////////////// |
| // Protected state. |
| //////////////////////////////////////////////////////////////// |
| |
| Hashtable prefixTable; |
| Hashtable uriTable; |
| Hashtable elementNameTable; |
| Hashtable attributeNameTable; |
| String defaultNS = null; |
| |
| |
| |
| //////////////////////////////////////////////////////////////// |
| // Internal state. |
| //////////////////////////////////////////////////////////////// |
| |
| private Vector declarations = null; |
| private boolean tablesDirty = false; |
| private Context parent = null; |
| } |
| } |
| |
| // end of NamespaceSupport.java |