From a148b0dc4e10dbf530cf734c0808d0fb4edd6719 Mon Sep 17 00:00:00 2001 From: David Winslow Date: Tue, 1 May 2012 14:44:55 -0400 Subject: [PATCH] Mark and reset for TranslatorSupport --- .../geotools/xml/transform/TransformerBase.java | 195 +++++++++++++++++++- 1 files changed, 188 insertions(+), 7 deletions(-) diff --git a/modules/library/main/src/main/java/org/geotools/xml/transform/TransformerBase.java b/modules/library/main/src/main/java/org/geotools/xml/transform/TransformerBase.java index 10a09f8..fad5193 100644 --- a/modules/library/main/src/main/java/org/geotools/xml/transform/TransformerBase.java +++ b/modules/library/main/src/main/java/org/geotools/xml/transform/TransformerBase.java @@ -18,8 +18,10 @@ package org.geotools.xml.transform; import java.io.StringWriter; import java.nio.charset.Charset; +import java.util.ArrayList; import java.util.HashMap; import java.util.Iterator; +import java.util.List; import java.util.Map; import java.util.Set; @@ -434,6 +436,94 @@ public abstract class TransformerBase { protected final Attributes NULL_ATTS = new AttributesImpl(); protected NamespaceSupport nsSupport = new NamespaceSupport(); protected SchemaLocationSupport schemaLocation; + + /** + * Is a mark currently set? + * + * @see #mark() + */ + private boolean marked; + + /** + * The queue of write operations pending for this translator. + * This should be empty if no mark is set. + */ + private List pending = new ArrayList(); + + /** + * An Action records a call to one of the SAX-event-generating methods + * on this translator. + */ + private interface Action { + void commit(); + } + + /** + * The Start class implements an Action corresponding to starting an + * XML element + */ + private class Start implements Action { + private final String element; + private final Attributes attributes; + + public Start(String element, Attributes attributes) { + this.element = element; + this.attributes = new AttributesImpl(attributes); + } + + public void commit() { + _start(element, attributes); + } + } + + /** + * The Chars class implements an Action corresponding to writing a text + * block in the XML output + */ + private class Chars implements Action { + private final String text; + + public Chars(String text) { + this.text = text; + } + + public void commit() { + _chars(text); + } + } + + /** + * The CData class implements an Action corresponding to writing a + * CDATA block in the XML output + */ + private class CData implements Action { + private final String text; + + public CData(String text) { + this.text = text; + } + + public void commit() { + _cdata(text); + } + } + + /** + * The End class implements an Action corresponding to closing an XML + * element + */ + private class End implements Action { + private final String element; + + public End(String element) { + this.element = element; + } + + public void commit() { + _end(element); + } + } + /** * Subclasses should check this flag in case an abort message was sent * and stop any internal iteration if false. @@ -454,11 +544,69 @@ public abstract class TransformerBase { this(contentHandler, prefix, nsURI); this.schemaLocation = schemaLocation; } - + public void abort() { running = false; } - + + /** + * Set a mark() to which we can later "roll back" writes. After a call + * to mark(), the Translator stores pending write operations in memory + * until commit() is called. The pending writes can be discarded with + * the reset() method. + * + * Typically, one would use marks in conjunction with an exception handler: + * + * 
+         *   void encodeFoo(Foo f) {
+         *     try {
+         *       mark();
+         *       element(foo.riskyMethod());
+         *       element(foo.dangerousMethod());
+         *       commit();
+         *     } catch (BadThingHappened disaster) {
+         *         mitigate(disaster);
+         *         reset();
+         *     }
+         *   }
+         *
+ * + * @throws IllegalStateException if a mark is already set + */ + protected void mark() { + if (marked) throw new IllegalStateException("Mark already set!"); + marked = true; + } + + /** + * Discard pending write operations after a mark() has been set. + * + * This method is safe to call even if no mark is set - so it returns + * to a "known good" state as far as marks are concerned. + * + * @see #mark() + */ + protected void reset() { + pending.clear(); + marked = false; + } + + /** + * Commit pending write operations. After setting a mark, this method + * will commit the pending writes. + * + * @see #mark() + * @throws IllegalStateException if no mark is set + */ + protected void commit() { + if (!marked) throw new IllegalStateException("Can't commit without a mark!"); + for (Action a : pending) { + a.commit(); + } + pending.clear(); + marked = false; + } + /** * Utility method to copy namespace declarations from "sub" translators * into this ns support... @@ -498,7 +646,7 @@ public abstract class TransformerBase { protected void element(String element, String content) { element(element, content, NULL_ATTS); } - + /** * Will only issue the provided element if content is non empty * @param element @@ -525,6 +673,14 @@ public abstract class TransformerBase { } protected void start(String element, Attributes atts) { + if (marked) { + pending.add(new Start(element, atts)); + } else { + _start(element, atts); + } + } + + private void _start(String element, Attributes atts) { try { String el = (prefix == null) ? element : (prefix + ":" + element); @@ -535,6 +691,14 @@ public abstract class TransformerBase { } protected void chars(String text) { + if (marked) { + pending.add(new Chars(text)); + } else { + _chars(text); + } + } + + private void _chars(String text) { try { char[] ch = text.toCharArray(); contentHandler.characters(ch, 0, ch.length); @@ -544,6 +708,14 @@ public abstract class TransformerBase { } protected void end(String element) { + if (marked) { + pending.add(new End(element)); + } else { + _end(element); + } + } + + private void _end(String element) { try { String el = (prefix == null) ? element : (prefix + ":" + element); @@ -553,13 +725,22 @@ public abstract class TransformerBase { } } - protected void cdata( String cdata ) { - if ( contentHandler instanceof LexicalHandler ) { + protected void cdata(String cdata) { + if (marked) { + pending.add(new CData(cdata)); + } else { + _cdata(cdata); + } + } + + private void _cdata(String cdata) { + if (contentHandler instanceof LexicalHandler) { LexicalHandler lexicalHandler = (LexicalHandler) contentHandler; try { lexicalHandler.startCDATA(); - chars(cdata); - lexicalHandler.endCDATA(); + char[] carray = cdata.toCharArray(); + contentHandler.characters(carray, 0, carray.length); + lexicalHandler.endCDATA(); } catch( SAXException e ) { throw new RuntimeException( e ); -- 1.7.7.6