1 /*
   2  * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
   3  * @LastModified: Oct 2017
   4  */
   5 /*
   6  * Licensed to the Apache Software Foundation (ASF) under one or more
   7  * contributor license agreements.  See the NOTICE file distributed with
   8  * this work for additional information regarding copyright ownership.
   9  * The ASF licenses this file to You under the Apache License, Version 2.0
  10  * (the "License"); you may not use this file except in compliance with
  11  * the License.  You may obtain a copy of the License at
  12  *
  13  *      http://www.apache.org/licenses/LICENSE-2.0
  14  *
  15  * Unless required by applicable law or agreed to in writing, software
  16  * distributed under the License is distributed on an "AS IS" BASIS,
  17  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  18  * See the License for the specific language governing permissions and
  19  * limitations under the License.
  20  */
  21 
  22 package com.sun.org.apache.xalan.internal.xsltc.compiler;
  23 
  24 import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
  25 import com.sun.org.apache.bcel.internal.generic.PUSH;
  26 import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;
  27 import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ErrorMsg;
  28 import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;
  29 import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
  30 import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;
  31 import java.util.List;
  32 
  33 /**
  34  * @author Jacek Ambroziak
  35  * @author Santiago Pericas-Geertsen

  36  */
  37 final class ElementAvailableCall extends FunctionCall {
  38 
  39     public ElementAvailableCall(QName fname, List<Expression> arguments) {
  40         super(fname, arguments);
  41     }
  42 
  43     /**
  44      * Force the argument to this function to be a literal string.
  45      */
  46     public Type typeCheck(SymbolTable stable) throws TypeCheckError {
  47         if (argument() instanceof LiteralExpr) {
  48             return _type = Type.Boolean;
  49         }
  50         ErrorMsg err = new ErrorMsg(ErrorMsg.NEED_LITERAL_ERR,
  51                                     "element-available", this);
  52         throw new TypeCheckError(err);
  53     }
  54 
  55     /**
  56      * Returns an object representing the compile-time evaluation
  57      * of an expression. We are only using this for function-available
  58      * and element-available at this time.
  59      */
  60     public Object evaluateAtCompileTime() {
  61         return getResult() ? Boolean.TRUE : Boolean.FALSE;
  62     }
  63 
  64     /**
  65      * Returns the result that this function will return
  66      */
  67     public boolean getResult() {
  68         try {
  69             final LiteralExpr arg = (LiteralExpr) argument();
  70             final String qname = arg.getValue();
  71             final int index = qname.indexOf(':');
  72             final String localName = (index > 0) ?
  73                 qname.substring(index + 1) : qname;
  74             return getParser().elementSupported(arg.getNamespace(),
  75                                                 localName);
  76         }
  77         catch (ClassCastException e) {
  78             return false;
  79         }
  80     }
  81 
  82     /**
  83      * Calls to 'element-available' are resolved at compile time since
  84      * the namespaces declared in the stylsheet are not available at run
  85      * time. Consequently, arguments to this function must be literals.
  86      */
  87     public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
  88         final ConstantPoolGen cpg = classGen.getConstantPool();
  89         final boolean result = getResult();
  90         methodGen.getInstructionList().append(new PUSH(cpg, result));
  91     }
  92 }
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