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.Vector;
  
  import org.apache.bcel.generic.ConstantPoolGen;
  import org.apache.bcel.generic.INVOKEVIRTUAL;
  import org.apache.bcel.generic.InstructionList;
  import org.apache.bcel.generic.PUSH;
  import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
  import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
  import org.apache.xalan.xsltc.compiler.util.StringType;
  import org.apache.xalan.xsltc.compiler.util.Type;
  import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
  
  /**
   * @author Morten Jorgensen
   * @author Santiago Pericas-Geertsen
   */
  final class KeyCall extends FunctionCall {
  
      /**
       * The name of the key.
       */
      private Expression _name;
  
      /**
       * The value to look up in the key/index.
       */
      private Expression _value;
  
      /**
       * The value's data type.
       */
      private Type _valueType; // The value's data type
  
      /**
       * Expanded qname when name is literal.
       */
      private QName _resolvedQName = null;
  
      /**
       * Get the parameters passed to function:
       *   key(String name, String value)
       *   key(String name, NodeSet value)
       * The 'arguments' vector should contain two parameters for key() calls,
       * one holding the key name and one holding the value(s) to look up. The
       * vector has only one parameter for id() calls (the key name is always
       * "##id" for id() calls).
       *
       * @param fname The function name (should be 'key' or 'id')
       * @param arguments A vector containing the arguments the the function
       */
      public KeyCall(QName fname, Vector arguments) {
  	super(fname, arguments);
  	switch(argumentCount()) {
  	case 1:
  	    _name = null;
  	    _value = argument(0);
  	    break;
  	case 2:
  	    _name = argument(0);
  	    _value = argument(1);
  	    break;
  	default:
  	    _name = _value = null;
  	    break;
  	}
      }
  
       /**
       * If this call to key() is in a top-level element like  another variable
       * or param, add a dependency between that top-level element and the 
       * referenced key. For example,
       *
       *   <xsl:key name="x" .../>
       *   <xsl:variable name="y" select="key('x', 1)"/>
       *
       * and assuming this class represents "key('x', 1)", add a reference 
       * between variable y and key x. Note that if 'x' is unknown statically
       * in key('x', 1), there's nothing we can do at this point.
       */
      public void addParentDependency() {
          // If name unknown statically, there's nothing we can do
          if (_resolvedQName == null) return;
          
  	SyntaxTreeNode node = this;
  	while (node != null && node instanceof TopLevelElement == false) {
  	    node = node.getParent();
  	}
          
          TopLevelElement parent = (TopLevelElement) node;        
          if (parent != null) {
              parent.addDependency(getSymbolTable().getKey(_resolvedQName));
          }        
      }
      
     /**
       * Type check the parameters for the id() or key() function.
       * The index name (for key() call only) must be a string or convertable
       * to a string, and the lookup-value must be a string or a node-set.
       * @param stable The parser's symbol table
       * @throws TypeCheckError When the parameters have illegal type
       */
      public Type typeCheck(SymbolTable stable) throws TypeCheckError {
  	final Type returnType = super.typeCheck(stable);
  
  	// Run type check on the key name (first argument) - must be a string,
  	// and if it is not it must be converted to one using string() rules.
  	if (_name != null) {
  	    final Type nameType = _name.typeCheck(stable); 
  
  	    if (_name instanceof LiteralExpr) {
  		final LiteralExpr literal = (LiteralExpr) _name;
  		_resolvedQName = 
  		    getParser().getQNameIgnoreDefaultNs(literal.getValue());
  	    }
  	    else if (nameType instanceof StringType == false) {
  		_name = new CastExpr(_name, Type.String);
  	    }
  	}
  
  	// Run type check on the value for this key. This value can be of
  	// any data type, so this should never cause any type-check errors.
          // If the value is a reference, then we have to defer the decision
          // of how to process it until run-time.
  	// If the value is known not to be a node-set, then it should be
          // converted to a string before the lookup is done. If the value is 
          // known to be a node-set then this process (convert to string, then
          // do lookup) should be applied to every node in the set, and the
          // result from all lookups should be added to the resulting node-set.
  	_valueType = _value.typeCheck(stable);
  
  	if (_valueType != Type.NodeSet
                  && _valueType != Type.Reference
                  && _valueType != Type.String) {
  	    _value = new CastExpr(_value, Type.String);
              _valueType = _value.typeCheck(stable);
  	}
  
      // If in a top-level element, create dependency to the referenced key
      addParentDependency();
      
  	return returnType;
      }
  
      /**
       * This method is called when the constructor is compiled in
       * Stylesheet.compileConstructor() and not as the syntax tree is traversed.
       * <p>This method will generate byte code that produces an iterator
       * for the nodes in the node set for the key or id function call.
       * @param classGen The Java class generator
       * @param methodGen The method generator
       */
      public void translate(ClassGenerator classGen,
  			  MethodGenerator methodGen) {
  	final ConstantPoolGen cpg = classGen.getConstantPool();
  	final InstructionList il = methodGen.getInstructionList();
  
  	// Returns the KeyIndex object of a given name
  	final int getKeyIndex = cpg.addMethodref(TRANSLET_CLASS,
  						 "getKeyIndex",
  						 "(Ljava/lang/String;)"+
  						 KEY_INDEX_SIG);
  
  	// KeyIndex.setDom(Dom) => void
  	final int keyDom = cpg.addMethodref(KEY_INDEX_CLASS,
  					    "setDom",
  					    "("+DOM_INTF_SIG+")V");
  
  	// Initialises a KeyIndex to return nodes with specific values
  	final int getKeyIterator =
                          cpg.addMethodref(KEY_INDEX_CLASS,
  					 "getKeyIndexIterator",
  					 "(" + _valueType.toSignature() + "Z)"
                                               + KEY_INDEX_ITERATOR_SIG);
  
          // Initialise the index specified in the first parameter of key()
          il.append(classGen.loadTranslet());
          if (_name == null) {
              il.append(new PUSH(cpg,"##id"));
          } else if (_resolvedQName != null) {
              il.append(new PUSH(cpg, _resolvedQName.toString()));
          } else {
              _name.translate(classGen, methodGen);
          }
  
          // Generate following byte code:
          //
          //   KeyIndex ki = translet.getKeyIndex(_name)
          //   ki.setDom(translet.dom);
          //   ki.getKeyIndexIterator(_value, true)  - for key()
          //        OR
          //   ki.getKeyIndexIterator(_value, false)  - for id()
          il.append(new INVOKEVIRTUAL(getKeyIndex));
          il.append(DUP);
          il.append(methodGen.loadDOM());
          il.append(new INVOKEVIRTUAL(keyDom));
  
          _value.translate(classGen, methodGen);
          il.append((_name != null) ? ICONST_1: ICONST_0);
          il.append(new INVOKEVIRTUAL(getKeyIterator));
      }
  }
  