message.java

java1.6众多例子参考

/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: Message.java,v 1.2.4.1 2005/09/02 06:47:02 pvedula Exp $
 */

package com.sun.org.apache.xalan.internal.xsltc.compiler;

import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
import com.sun.org.apache.bcel.internal.generic.INVOKESPECIAL;
import com.sun.org.apache.bcel.internal.generic.INVOKEVIRTUAL;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.bcel.internal.generic.NEW;
import com.sun.org.apache.bcel.internal.generic.PUSH;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author Morten Jorgensen
 */
final class Message extends Instruction {
    private boolean _terminate = false;

    public void parseContents(Parser parser) {
	String termstr = getAttribute("terminate");
	if (termstr != null) {
            _terminate = termstr.equals("yes");
	}
	parseChildren(parser);
    }

    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
	typeCheckContents(stable);
	return Type.Void;
    }

    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = methodGen.getInstructionList();

	// Load the translet (for call to displayMessage() function)
	il.append(classGen.loadTranslet());

        switch (elementCount()) {
            case 0:
                il.append(new PUSH(cpg, ""));
            break;
            case 1:
                SyntaxTreeNode child = (SyntaxTreeNode) elementAt(0);
                if (child instanceof Text) {
                    il.append(new PUSH(cpg, ((Text) child).getText()));
                    break;
                }
                // falls through
            default:
                // Push current output handler onto the stack
                il.append(methodGen.loadHandler());

                // Replace the current output handler by a ToXMLStream
                il.append(new NEW(cpg.addClass(STREAM_XML_OUTPUT)));
                il.append(methodGen.storeHandler());

                // Push a reference to a StringWriter
                il.append(new NEW(cpg.addClass(STRING_WRITER)));
                il.append(DUP);
                il.append(DUP);
                il.append(new INVOKESPECIAL(
                    cpg.addMethodref(STRING_WRITER, "<init>", "()V")));

                // Load ToXMLStream
                il.append(methodGen.loadHandler());
                il.append(new INVOKESPECIAL(
                    cpg.addMethodref(STREAM_XML_OUTPUT, "<init>",
                                     "()V")));

                // Invoke output.setWriter(STRING_WRITER)
                il.append(methodGen.loadHandler());
                il.append(SWAP);
                il.append(new INVOKEVIRTUAL(
                    cpg.addMethodref(OUTPUT_BASE, "setWriter",
                                     "("+WRITER_SIG+")V")));

                // Invoke output.setEncoding("UTF-8")
                il.append(methodGen.loadHandler());
                il.append(new PUSH(cpg, "UTF-8"));   // other encodings?
                il.append(new INVOKEVIRTUAL(
                    cpg.addMethodref(OUTPUT_BASE, "setEncoding",
                                     "("+STRING_SIG+")V")));

                // Invoke output.setOmitXMLDeclaration(true)
                il.append(methodGen.loadHandler());
                il.append(ICONST_1);
                il.append(new INVOKEVIRTUAL(
                    cpg.addMethodref(OUTPUT_BASE, "setOmitXMLDeclaration",
                                     "(Z)V")));

                il.append(methodGen.loadHandler());
                il.append(new INVOKEVIRTUAL(
                    cpg.addMethodref(OUTPUT_BASE, "startDocument",
                                     "()V")));

                // Inline translation of contents
                translateContents(classGen, methodGen);

                il.append(methodGen.loadHandler());
                il.append(new INVOKEVIRTUAL(
                    cpg.addMethodref(OUTPUT_BASE, "endDocument",
                                     "()V")));

                // Call toString() on StringWriter
                il.append(new INVOKEVIRTUAL(
                    cpg.addMethodref(STRING_WRITER, "toString",
                                     "()" + STRING_SIG)));

                // Restore old output handler
                il.append(SWAP);
                il.append(methodGen.storeHandler());
            break;
        }

	// Send the resulting string to the message handling method
	il.append(new INVOKEVIRTUAL(cpg.addMethodref(TRANSLET_CLASS,
						     "displayMessage",
						     "("+STRING_SIG+")V")));

	// If 'terminate' attribute is set to 'yes': Instanciate a
	// RunTimeException, but it on the stack and throw an exception
	if (_terminate == true) {
	    // Create a new instance of RunTimeException
	    final int einit = cpg.addMethodref("java.lang.RuntimeException",
					       "<init>",
					       "(Ljava/lang/String;)V");
	    il.append(new NEW(cpg.addClass("java.lang.RuntimeException")));
	    il.append(DUP);
	    il.append(new PUSH(cpg,"Termination forced by an " +
			           "xsl:message instruction"));
	    il.append(new INVOKESPECIAL(einit));
	    il.append(ATHROW);
	}
    }

}