code: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements. See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership. The ASF licenses this file
   * to you 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.
   */
  /*
   * $Id$
   */
  
  package org.apache.xalan.xsltc.compiler;
  
  import java.util.Enumeration;
  import java.util.Vector;
  import java.util.StringTokenizer;
  import java.util.NoSuchElementException;
  
  import org.apache.bcel.generic.ConstantPoolGen;
  import org.apache.bcel.generic.INVOKESPECIAL;
  import org.apache.bcel.generic.INVOKEVIRTUAL;
  import org.apache.bcel.generic.Instruction;
  import org.apache.bcel.generic.InstructionList;
  import org.apache.bcel.generic.NEW;
  import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
  import org.apache.xalan.xsltc.compiler.util.ErrorMsg;
  import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
  import org.apache.xalan.xsltc.compiler.util.Type;
  import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
  
  /**
   * @author Jacek Ambroziak
   * @author Santiago Pericas-Geertsen
   */
  final class AttributeValueTemplate extends AttributeValue {
      
      final static int OUT_EXPR = 0;
      final static int IN_EXPR  = 1;
      final static int IN_EXPR_SQUOTES = 2;
      final static int IN_EXPR_DQUOTES = 3;
      final static String DELIMITER = "\uFFFE";      // A Unicode nonchar
  
      public AttributeValueTemplate(String value, Parser parser, 
  	SyntaxTreeNode parent) 
      {
  	setParent(parent);
  	setParser(parser);
          
          try {
              parseAVTemplate(value, parser);
          }
          catch (NoSuchElementException e) {
              reportError(parent, parser,
                          ErrorMsg.ATTR_VAL_TEMPLATE_ERR, value);            
          }
      }
  
      /**
       * Two-pass parsing of ATVs. In the first pass, double curly braces are 
       * replaced by one, and expressions are delimited using DELIMITER. The 
       * second pass splits up the resulting buffer into literal and non-literal
       * expressions. Errors are reported during the first pass.
       */
      private void parseAVTemplate(String text, Parser parser) {
          StringTokenizer tokenizer = 
              new StringTokenizer(text, "{}\"\'", true);
          
          /*
            * First pass: replace double curly braces and delimit expressions
            * Simple automaton to parse ATVs, delimit expressions and report
            * errors.
            */
          String t = null;
          String lookahead = null;
          StringBuffer buffer = new StringBuffer();
          int state = OUT_EXPR;
          
          while (tokenizer.hasMoreTokens()) {            
              // Use lookahead if available
              if (lookahead != null) {
                  t = lookahead;
                  lookahead = null;
              }
              else {
                  t = tokenizer.nextToken();
              }
              
              if (t.length() == 1) {
                  switch (t.charAt(0)) {
                      case '{':
                          switch (state) {
                              case OUT_EXPR:
                                  lookahead = tokenizer.nextToken();
                                  if (lookahead.equals("{")) {
                                      buffer.append(lookahead);    // replace {{ by {
                                      lookahead = null;
                                  }
                                  else {
                                      buffer.append(DELIMITER);
                                      state = IN_EXPR;                                    
                                  }
                                  break;
                              case IN_EXPR:
                              case IN_EXPR_SQUOTES:
                              case IN_EXPR_DQUOTES:
                                  reportError(getParent(), parser,
                                              ErrorMsg.ATTR_VAL_TEMPLATE_ERR, text);
                                  break;
                          }                                                
                          break;
                      case '}':
                          switch (state) {
                              case OUT_EXPR:
                                  lookahead = tokenizer.nextToken();
                                  if (lookahead.equals("}")) {
                                      buffer.append(lookahead);    // replace }} by }
                                      lookahead = null;
                                  }
                                  else {
                                      reportError(getParent(), parser,
                                              ErrorMsg.ATTR_VAL_TEMPLATE_ERR, text);
                                  }
                                  break;
                              case IN_EXPR:
                                  buffer.append(DELIMITER);
                                  state = OUT_EXPR;
                                  break;
                              case IN_EXPR_SQUOTES:
                              case IN_EXPR_DQUOTES:
                                  buffer.append(t);
                                  break;
                          }
                          break;
                      case '\'':
                          switch (state) {
                              case IN_EXPR:
                                  state = IN_EXPR_SQUOTES;
                                  break;
                              case IN_EXPR_SQUOTES:
                                  state = IN_EXPR;
                                  break;
                              case OUT_EXPR:
                              case IN_EXPR_DQUOTES:
                                  break;
                          }
                          buffer.append(t);
                          break;
                      case '\"':
                          switch (state) {
                              case IN_EXPR:
                                  state = IN_EXPR_DQUOTES;
                                  break;
                              case IN_EXPR_DQUOTES:
                                  state = IN_EXPR;
                                  break;
                              case OUT_EXPR:
                              case IN_EXPR_SQUOTES:
                                  break;
                          }
                          buffer.append(t);
                          break;
                      default:
                          buffer.append(t);
                          break;
                  }
              }
              else {
                  buffer.append(t);
              }
          }
  
          // Must be in OUT_EXPR at the end of parsing
          if (state != OUT_EXPR) {
              reportError(getParent(), parser,
                          ErrorMsg.ATTR_VAL_TEMPLATE_ERR, text);
          }
          
          /*
            * Second pass: split up buffer into literal and non-literal expressions.
            */
          tokenizer = new StringTokenizer(buffer.toString(), DELIMITER, true);
          
          while (tokenizer.hasMoreTokens()) {
              t = tokenizer.nextToken();
              
              if (t.equals(DELIMITER)) {
  		addElement(parser.parseExpression(this, tokenizer.nextToken()));
                  tokenizer.nextToken();      // consume other delimiter
              }
              else {
  		addElement(new LiteralExpr(t)); 
              }
          }        
      }
  
      public Type typeCheck(SymbolTable stable) throws TypeCheckError {
  	final Vector contents = getContents();
  	final int n = contents.size();
  	for (int i = 0; i < n; i++) {
  	    final Expression exp = (Expression)contents.elementAt(i);
  	    if (!exp.typeCheck(stable).identicalTo(Type.String)) {
  		contents.setElementAt(new CastExpr(exp, Type.String), i);
  	    }
  	}
  	return _type = Type.String;
      }
  
      public String toString() {
  	final StringBuffer buffer = new StringBuffer("AVT:[");
  	final int count = elementCount();
  	for (int i = 0; i < count; i++) {
  	    buffer.append(elementAt(i).toString());
  	    if (i < count - 1)
  		buffer.append(' ');
  	}
  	return buffer.append(']').toString();
      }
  		
      public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
  	if (elementCount() == 1) {
  	    final Expression exp = (Expression)elementAt(0);
  	    exp.translate(classGen, methodGen);
  	}
  	else {
  	    final ConstantPoolGen cpg = classGen.getConstantPool();
  	    final InstructionList il = methodGen.getInstructionList();
  	    final int initBuffer = cpg.addMethodref(STRING_BUFFER_CLASS,
  						    "<init>", "()V");
  	    final Instruction append =
  		new INVOKEVIRTUAL(cpg.addMethodref(STRING_BUFFER_CLASS,
  						   "append",
  						   "(" + STRING_SIG + ")"
  						   + STRING_BUFFER_SIG));
  	    
  	    final int toString = cpg.addMethodref(STRING_BUFFER_CLASS,
  						  "toString",
  						  "()"+STRING_SIG);
  	    il.append(new NEW(cpg.addClass(STRING_BUFFER_CLASS)));
  	    il.append(DUP);
  	    il.append(new INVOKESPECIAL(initBuffer));
  	    // StringBuffer is on the stack
  	    final Enumeration elements = elements();
  	    while (elements.hasMoreElements()) {
  		final Expression exp = (Expression)elements.nextElement();
  		exp.translate(classGen, methodGen);
  		il.append(append);
  	    }
  	    il.append(new INVOKEVIRTUAL(toString));
  	}
      }
  }
  