1 /*

     2  * reserved comment block

     3  * DO NOT REMOVE OR ALTER!

     4  */

     5 /*

     6  * Copyright 2001-2004 The Apache Software Foundation.

     7  *

     8  * Licensed under the Apache License, Version 2.0 (the "License");

     9  * you may not use this file except in compliance with the License.

    10  * You may obtain a copy of the License at

    11  *

    12  *     http://www.apache.org/licenses/LICENSE-2.0

    13  *

    14  * Unless required by applicable law or agreed to in writing, software

    15  * distributed under the License is distributed on an "AS IS" BASIS,

    16  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

    17  * See the License for the specific language governing permissions and

    18  * limitations under the License.

    19  */

    20 /*

    21  * $Id: VariableBase.java,v 1.5 2005/09/28 13:48:18 pvedula Exp $

    22  */

    23 

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

    25 

    26 import java.util.Vector;

    27 

    28 import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;

    29 import com.sun.org.apache.bcel.internal.generic.Instruction;

    30 import com.sun.org.apache.bcel.internal.generic.InstructionList;

    31 import com.sun.org.apache.bcel.internal.generic.INVOKESPECIAL;

    32 import com.sun.org.apache.bcel.internal.generic.LocalVariableGen;

    33 import com.sun.org.apache.bcel.internal.generic.NEW;

    34 import com.sun.org.apache.bcel.internal.generic.PUSH;

    35 import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;

    36 import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ErrorMsg;

    37 import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;

    38 import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NodeSetType;

    39 import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;

    40 import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Util;

    41 import com.sun.org.apache.xml.internal.utils.XML11Char;

    42 

    43 /**

    44  * @author Jacek Ambroziak

    45  * @author Santiago Pericas-Geertsen

    46  * @author Morten Jorgensen

    47  * @author Erwin Bolwidt <ejb@klomp.org>

    48  * @author John Howard <JohnH@schemasoft.com>

    49  */

    50 class VariableBase extends TopLevelElement {

    51 

    52     protected QName       _name;            // The name of the variable.

    53     protected String      _escapedName;        // The escaped qname of the variable.

    54     protected Type        _type;            // The type of this variable.

    55     protected boolean     _isLocal;         // True if the variable is local.

    56     protected LocalVariableGen _local;      // Reference to JVM variable

    57     protected Instruction _loadInstruction; // Instruction to load JVM variable

    58     protected Instruction _storeInstruction; // Instruction to load JVM variable

    59     protected Expression  _select;          // Reference to variable expression

    60     protected String      select;           // Textual repr. of variable expr.

    61 

    62     // References to this variable (when local)

    63     protected Vector      _refs = new Vector(2);

    64 

    65     // Dependencies to other variables/parameters (for globals only)

    66     protected Vector      _dependencies = null;

    67 

    68     // Used to make sure parameter field is not added twice

    69     protected boolean    _ignore = false;

    70 

    71     /**

    72      * Disable this variable/parameter

    73      */

    74     public void disable() {

    75         _ignore = true;

    76     }

    77 

    78     /**

    79      * Add a reference to this variable. Called by VariableRef when an

    80      * expression contains a reference to this variable.

    81      */

    82     public void addReference(VariableRefBase vref) {

    83         _refs.addElement(vref);

    84     }

    85 

    86     /**

    87      * Remove a reference to this variable. Called by VariableRef when this

    88      * variable goes out of scope.

    89      */

    90     public void removeReference(VariableRefBase vref) {

    91         _refs.remove(vref);

    92     }

    93 

    94     /**

    95      * When a variable is overriden by another, e.g. via xsl:import,

    96      * its references need to be copied or otherwise it may be

    97      * compiled away as dead code. This method can be used for that

    98      * purpose.

    99      */

   100     public void copyReferences(VariableBase var) {

   101         final int size = _refs.size();

   102         for (int i = 0; i < size; i++) {

   103             var.addReference((VariableRefBase) _refs.get(i));

   104         }

   105     }

   106 

   107     /**

   108      * Map this variable to a register

   109      */

   110     public void mapRegister(MethodGenerator methodGen) {

   111         if (_local == null) {

   112             final InstructionList il = methodGen.getInstructionList();

   113             final String name = getEscapedName(); // TODO: namespace ?

   114             final com.sun.org.apache.bcel.internal.generic.Type varType = _type.toJCType();

   115             _local = methodGen.addLocalVariable2(name, varType, il.getEnd());

   116         }

   117     }

   118 

   119     /**

   120      * Remove the mapping of this variable to a register.

   121      * Called when we leave the AST scope of the variable's declaration

   122      */

   123     public void unmapRegister(MethodGenerator methodGen) {

   124         if (_refs.isEmpty() && (_local != null)) {

   125             _local.setEnd(methodGen.getInstructionList().getEnd());

   126             methodGen.removeLocalVariable(_local);

   127             _refs = null;

   128             _local = null;

   129         }

   130     }

   131 

   132     /**

   133      * Returns an instruction for loading the value of this variable onto

   134      * the JVM stack.

   135      */

   136     public Instruction loadInstruction() {

   137         final Instruction instr = _loadInstruction;

   138         if (_loadInstruction == null) {

   139             _loadInstruction = _type.LOAD(_local.getIndex());

   140         }

   141         return _loadInstruction;

   142     }

   143 

   144     /**

   145      * Returns an instruction for storing a value from the JVM stack

   146      * into this variable.

   147      */

   148     public Instruction storeInstruction() {

   149         final Instruction instr = _storeInstruction;

   150         if (_storeInstruction == null) {

   151             _storeInstruction = _type.STORE(_local.getIndex());

   152         }

   153         return _storeInstruction;

   154     }

   155 

   156     /**

   157      * Returns the expression from this variable's select attribute (if any)

   158      */

   159     public Expression getExpression() {

   160         return(_select);

   161     }

   162 

   163     /**

   164      * Display variable as single string

   165      */

   166     public String toString() {

   167         return("variable("+_name+")");

   168     }

   169 

   170     /**

   171      * Display variable in a full AST dump

   172      */

   173     public void display(int indent) {

   174         indent(indent);

   175         System.out.println("Variable " + _name);

   176         if (_select != null) {

   177             indent(indent + IndentIncrement);

   178             System.out.println("select " + _select.toString());

   179         }

   180         displayContents(indent + IndentIncrement);

   181     }

   182 

   183     /**

   184      * Returns the type of the variable

   185      */

   186     public Type getType() {

   187         return _type;

   188     }

   189 

   190     /**

   191      * Returns the name of the variable or parameter as it will occur in the

   192      * compiled translet.

   193      */

   194     public QName getName() {

   195         return _name;

   196     }

   197 

   198     /**

   199      * Returns the escaped qname of the variable or parameter

   200      */

   201     public String getEscapedName() {

   202         return _escapedName;

   203     }

   204 

   205     /**

   206      * Set the name of the variable or paremeter. Escape all special chars.

   207      */

   208     public void setName(QName name) {

   209         _name = name;

   210         _escapedName = Util.escape(name.getStringRep());

   211     }

   212 

   213     /**

   214      * Returns the true if the variable is local

   215      */

   216     public boolean isLocal() {

   217         return _isLocal;

   218     }

   219 

   220     /**

   221      * Parse the contents of the <xsl:decimal-format> element.

   222      */

   223     public void parseContents(Parser parser) {

   224         // Get the 'name attribute

   225         String name = getAttribute("name");

   226 

   227         if (name.length() > 0) {

   228             if (!XML11Char.isXML11ValidQName(name)) {

   229                 ErrorMsg err = new ErrorMsg(ErrorMsg.INVALID_QNAME_ERR, name, this);

   230                 parser.reportError(Constants.ERROR, err);

   231             }

   232             setName(parser.getQNameIgnoreDefaultNs(name));

   233         }

   234         else

   235             reportError(this, parser, ErrorMsg.REQUIRED_ATTR_ERR, "name");

   236 

   237         // Check whether variable/param of the same name is already in scope

   238         VariableBase other = parser.lookupVariable(_name);

   239         if ((other != null) && (other.getParent() == getParent())) {

   240             reportError(this, parser, ErrorMsg.VARIABLE_REDEF_ERR, name);

   241         }

   242 

   243         select = getAttribute("select");

   244         if (select.length() > 0) {

   245             _select = getParser().parseExpression(this, "select", null);

   246             if (_select.isDummy()) {

   247                 reportError(this, parser, ErrorMsg.REQUIRED_ATTR_ERR, "select");

   248                 return;

   249             }

   250         }

   251 

   252         // Children must be parsed first -> static scoping

   253         parseChildren(parser);

   254     }

   255 

   256     /**

   257      * Compile the value of the variable, which is either in an expression in

   258      * a 'select' attribute, or in the variable elements body

   259      */

   260     public void translateValue(ClassGenerator classGen,

   261                                MethodGenerator methodGen) {

   262         // Compile expression is 'select' attribute if present

   263         if (_select != null) {

   264             _select.translate(classGen, methodGen);

   265             // Create a CachedNodeListIterator for select expressions

   266             // in a variable or parameter.

   267             if (_select.getType() instanceof NodeSetType) {

   268                 final ConstantPoolGen cpg = classGen.getConstantPool();

   269                 final InstructionList il = methodGen.getInstructionList();

   270 

   271                 final int initCNI = cpg.addMethodref(CACHED_NODE_LIST_ITERATOR_CLASS,

   272                                             "<init>",

   273                                             "("

   274                                             +NODE_ITERATOR_SIG

   275                                             +")V");

   276                 il.append(new NEW(cpg.addClass(CACHED_NODE_LIST_ITERATOR_CLASS)));

   277                 il.append(DUP_X1);

   278                 il.append(SWAP);

   279 

   280                 il.append(new INVOKESPECIAL(initCNI));

   281             }

   282             _select.startIterator(classGen, methodGen);

   283         }

   284         // If not, compile result tree from parameter body if present.

   285         else if (hasContents()) {

   286             compileResultTree(classGen, methodGen);

   287         }

   288         // If neither are present then store empty string in variable

   289         else {

   290             final ConstantPoolGen cpg = classGen.getConstantPool();

   291             final InstructionList il = methodGen.getInstructionList();

   292             il.append(new PUSH(cpg, Constants.EMPTYSTRING));

   293         }

   294     }

   295 

   296 }