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 org.apache.bcel.classfile.Field;
  import org.apache.bcel.generic.BranchHandle;
  import org.apache.bcel.generic.CHECKCAST;
  import org.apache.bcel.generic.IFNONNULL;
  import org.apache.bcel.generic.ConstantPoolGen;
  import org.apache.bcel.generic.INVOKEVIRTUAL;
  import org.apache.bcel.generic.Instruction;
  import org.apache.bcel.generic.InstructionList;
  import org.apache.bcel.generic.PUSH;
  import org.apache.bcel.generic.PUTFIELD;
  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.ReferenceType;
  import org.apache.xalan.xsltc.compiler.util.Type;
  import org.apache.xalan.xsltc.compiler.util.ObjectType;
  import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
  import org.apache.xalan.xsltc.runtime.BasisLibrary;
  
  /**
   * @author Jacek Ambroziak
   * @author Santiago Pericas-Geertsen
   * @author Morten Jorgensen
   * @author Erwin Bolwidt <ejb@klomp.org>
   * @author John Howard <JohnH@schemasoft.com>
   */
  final class Param extends VariableBase {
  
      /**
       * True if this Param is declared in a simple named template.
       * This is used to optimize codegen for parameter passing
       * in named templates.
       */
      private boolean _isInSimpleNamedTemplate = false;
  
      /**
       * Display variable as single string
       */
      public String toString() {
  	return "param(" + _name + ")";
      }
  
      /**
       * Set the instruction for loading the value of this variable onto the 
       * JVM stack and returns the old instruction.
       */
      public Instruction setLoadInstruction(Instruction instruction) {
          Instruction tmp = _loadInstruction;
          _loadInstruction = instruction;
          return tmp;
      }
  
      /**
       * Set the instruction for storing a value from the stack into this
       * variable and returns the old instruction.
       */
      public Instruction setStoreInstruction(Instruction instruction) {
          Instruction tmp = _storeInstruction;
          _storeInstruction = instruction;
          return tmp;
      }
  
      /**
       * Display variable in a full AST dump
       */
      public void display(int indent) {
  	indent(indent);
  	System.out.println("param " + _name);
  	if (_select != null) {
  	    indent(indent + IndentIncrement);
  	    System.out.println("select " + _select.toString());
  	}
  	displayContents(indent + IndentIncrement);
      }
  
      /**
       * Parse the contents of the <xsl:param> element. This method must read
       * the 'name' (required) and 'select' (optional) attributes.
       */
      public void parseContents(Parser parser) {
  
  	// Parse 'name' and 'select' attributes plus parameter contents
  	super.parseContents(parser);
  
  	// Add a ref to this param to its enclosing construct
  	final SyntaxTreeNode parent = getParent();
  	if (parent instanceof Stylesheet) {
  	    // Mark this as a global parameter
  	    _isLocal = false;
  	    // Check if a global variable with this name already exists...
  	    Param param = parser.getSymbolTable().lookupParam(_name);
  	    // ...and if it does we need to check import precedence
  	    if (param != null) {
  		final int us = this.getImportPrecedence();
  		final int them = param.getImportPrecedence();
  		// It is an error if the two have the same import precedence
  		if (us == them) {
  		    final String name = _name.toString();
  		    reportError(this, parser, ErrorMsg.VARIABLE_REDEF_ERR,name);
  		}
  		// Ignore this if previous definition has higher precedence
  		else if (them > us) {
  		    _ignore = true;
  		    return;
  		}
  		else {
  		    param.disable();
  		}
  	    }
  	    // Add this variable if we have higher precedence
  	    ((Stylesheet)parent).addParam(this);
  	    parser.getSymbolTable().addParam(this);
  	}
  	else if (parent instanceof Template) {
              Template template = (Template) parent;
  	    _isLocal = true;
              template.addParameter(this);
              if (template.isSimpleNamedTemplate()) {
                  _isInSimpleNamedTemplate = true;
              }
  	}
      }
  
      /**
       * Type-checks the parameter. The parameter type is determined by the
       * 'select' expression (if present) or is a result tree if the parameter
       * element has a body and no 'select' expression.
       */
      public Type typeCheck(SymbolTable stable) throws TypeCheckError {
  	if (_select != null) {
  	    _type = _select.typeCheck(stable); 
  	    if (_type instanceof ReferenceType == false && !(_type instanceof ObjectType)) {
  		_select = new CastExpr(_select, Type.Reference);
  	    }
  	}
  	else if (hasContents()) {
  	    typeCheckContents(stable);
  	}
  	_type = Type.Reference;
  
  	// This element has no type (the parameter does, but the parameter
  	// element itself does not).
  	return Type.Void;
      }
  
      public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
  	final ConstantPoolGen cpg = classGen.getConstantPool();
  	final InstructionList il = methodGen.getInstructionList();
  
  	if (_ignore) return;
  	_ignore = true;
  
          /*
           * To fix bug 24518 related to setting parameters of the form
           * {namespaceuri}localName which will get mapped to an instance 
           * variable in the class.
           */
  	final String name = BasisLibrary.mapQNameToJavaName(_name.toString());
  	final String signature = _type.toSignature();
  	final String className = _type.getClassName();
  
  	if (isLocal()) {
              /*
                * If simple named template then generate a conditional init of the 
                * param using its default value: 
                *       if (param == null) param = <default-value>
                */
              if (_isInSimpleNamedTemplate) {
  		il.append(loadInstruction());
                  BranchHandle ifBlock = il.append(new IFNONNULL(null));
                  translateValue(classGen, methodGen);
                  il.append(storeInstruction());
                  ifBlock.setTarget(il.append(NOP));
                  return;
              }
              
  	    il.append(classGen.loadTranslet());
  	    il.append(new PUSH(cpg, name));
  	    translateValue(classGen, methodGen);
  	    il.append(new PUSH(cpg, true));
  
  	    // Call addParameter() from this class
  	    il.append(new INVOKEVIRTUAL(cpg.addMethodref(TRANSLET_CLASS,
  							 ADD_PARAMETER,
  							 ADD_PARAMETER_SIG)));
  	    if (className != EMPTYSTRING) {
  		il.append(new CHECKCAST(cpg.addClass(className)));
  	    }
  
  	    _type.translateUnBox(classGen, methodGen);
  
  	    if (_refs.isEmpty()) { // nobody uses the value
  		il.append(_type.POP());
  		_local = null;
  	    }
  	    else {		// normal case
  		_local = methodGen.addLocalVariable2(name,
  						     _type.toJCType(),
  						     null);
  		// Cache the result of addParameter() in a local variable
  		_local.setStart(il.append(_type.STORE(_local.getIndex())));
  	    }
  	}
  	else {
  	    if (classGen.containsField(name) == null) {
  		classGen.addField(new Field(ACC_PUBLIC, cpg.addUtf8(name),
  					    cpg.addUtf8(signature),
  					    null, cpg.getConstantPool()));
  		il.append(classGen.loadTranslet());
  		il.append(DUP);
  		il.append(new PUSH(cpg, name));
  		translateValue(classGen, methodGen);
  		il.append(new PUSH(cpg, true));
  
  		// Call addParameter() from this class
  		il.append(new INVOKEVIRTUAL(cpg.addMethodref(TRANSLET_CLASS,
  						     ADD_PARAMETER,
  						     ADD_PARAMETER_SIG)));
  
  		_type.translateUnBox(classGen, methodGen);
  
  		// Cache the result of addParameter() in a field
  		if (className != EMPTYSTRING) {
  		    il.append(new CHECKCAST(cpg.addClass(className)));
  		}
  		il.append(new PUTFIELD(cpg.addFieldref(classGen.getClassName(),
  						       name, signature)));
  	    }
  	}
      }
  }
  