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   *
   *  AndroidIDE is free software: you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License as published by
   *  the Free Software Foundation, either version 3 of the License, or
   *  (at your option) any later version.
   *
   *  AndroidIDE is distributed in the hope that it will be useful,
   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *  GNU General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License
   *   along with AndroidIDE.  If not, see <https://www.gnu.org/licenses/>.
   */
  
  /*
   * reserved comment block
   * DO NOT REMOVE OR ALTER!
   */
  /*
   * Copyright 2001-2004 The Apache Software Foundation.
   *
   * Licensed 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: Expression.java,v 1.2.4.1 2005/09/01 14:17:51 pvedula Exp $
   */
  
  package jaxp.sun.org.apache.xalan.internal.xsltc.compiler;
  
  import java.util.Vector;
  
  import jaxp.sun.org.apache.bcel.internal.generic.BranchHandle;
  import jaxp.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
  import jaxp.sun.org.apache.bcel.internal.generic.GOTO_W;
  import jaxp.sun.org.apache.bcel.internal.generic.IFEQ;
  import jaxp.sun.org.apache.bcel.internal.generic.InstructionHandle;
  import jaxp.sun.org.apache.bcel.internal.generic.InstructionList;
  import jaxp.sun.org.apache.xalan.internal.xsltc.compiler.util.BooleanType;
  import jaxp.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;
  import jaxp.sun.org.apache.xalan.internal.xsltc.compiler.util.ErrorMsg;
  import jaxp.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;
  import jaxp.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodType;
  import jaxp.sun.org.apache.xalan.internal.xsltc.compiler.util.NodeSetType;
  import jaxp.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
  import jaxp.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;
  
  /**
   * @author Jacek Ambroziak
   * @author Santiago Pericas-Geertsen
   * @author Morten Jorgensen
   * @author Erwin Bolwidt <ejb@klomp.org>
   */
  abstract class Expression extends SyntaxTreeNode {
      /**
       * The type of this expression. It is set after calling
       * <code>typeCheck()</code>.
       */
      protected Type _type;
  
      /**
       * Instruction handles that comprise the true list.
       */
      protected FlowList _trueList = new FlowList();
  
      /**
       * Instruction handles that comprise the false list.
       */
      protected FlowList _falseList = new FlowList();
  
      public Type getType() {
          return _type;
      }
  
      public abstract String toString();
  
      public boolean hasPositionCall() {
          return false;           // default should be 'false' for StepPattern
      }
  
      public boolean hasLastCall() {
          return false;
      }
  
      /**
       * Returns an object representing the compile-time evaluation
       * of an expression. We are only using this for function-available
       * and element-available at this time.
       */
      public Object evaluateAtCompileTime() {
          return null;
      }
  
      /**
       * Type check all the children of this node.
       */
      public Type typeCheck(SymbolTable stable) throws TypeCheckError {
          return typeCheckContents(stable);
      }
  
      /**
       * Translate this node into JVM bytecodes.
       */
      public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
          ErrorMsg msg = new ErrorMsg(ErrorMsg.NOT_IMPLEMENTED_ERR,
                                      getClass(), this);
          getParser().reportError(FATAL, msg);
      }
  
      /**
       * Translate this node into a fresh instruction list.
       * The original instruction list is saved and restored.
       */
      public final InstructionList compile(ClassGenerator classGen,
                                           MethodGenerator methodGen) {
          final InstructionList result, save = methodGen.getInstructionList();
          methodGen.setInstructionList(result = new InstructionList());
          translate(classGen, methodGen);
          methodGen.setInstructionList(save);
          return result;
      }
  
      /**
       * Redefined by expressions of type boolean that use flow lists.
       */
      public void translateDesynthesized(ClassGenerator classGen,
                                         MethodGenerator methodGen) {
          translate(classGen, methodGen);
          if (_type instanceof BooleanType) {
              desynthesize(classGen, methodGen);
          }
      }
  
      /**
       * If this expression is of type node-set and it is not a variable
       * reference, then call setStartNode() passing the context node.
       */
      public void startIterator(ClassGenerator classGen,
                                     MethodGenerator methodGen) {
          // Ignore if type is not node-set
          if (_type instanceof NodeSetType == false) {
              return;
          }
  
          // setStartNode() should not be called if expr is a variable ref
          Expression expr = this;
          if (expr instanceof CastExpr) {
              expr = ((CastExpr) expr).getExpr();
          }
          if (expr instanceof VariableRefBase == false) {
              final InstructionList il = methodGen.getInstructionList();
              il.append(methodGen.loadContextNode());
              il.append(methodGen.setStartNode());
          }
      }
  
      /**
       * Synthesize a boolean expression, i.e., either push a 0 or 1 onto the
       * operand stack for the next statement to succeed. Returns the handle
       * of the instruction to be backpatched.
       */
      public void synthesize(ClassGenerator classGen, MethodGenerator methodGen) {
          final ConstantPoolGen cpg = classGen.getConstantPool();
          final InstructionList il = methodGen.getInstructionList();
          _trueList.backPatch(il.append(ICONST_1));
          final BranchHandle truec = il.append(new GOTO_W(null));
          _falseList.backPatch(il.append(ICONST_0));
          truec.setTarget(il.append(NOP));
      }
  
      public void desynthesize(ClassGenerator classGen,
                               MethodGenerator methodGen) {
          final InstructionList il = methodGen.getInstructionList();
          _falseList.add(il.append(new IFEQ(null)));
      }
  
      public FlowList getFalseList() {
          return _falseList;
      }
  
      public FlowList getTrueList() {
          return _trueList;
      }
  
      public void backPatchFalseList(InstructionHandle ih) {
          _falseList.backPatch(ih);
      }
  
      public void backPatchTrueList(InstructionHandle ih) {
          _trueList.backPatch(ih);
      }
  
      /**
       * Search for a primop in the symbol table that matches the method type
       * <code>ctype</code>. Two methods match if they have the same arity.
       * If a primop is overloaded then the "closest match" is returned. The
       * first entry in the vector of primops that has the right arity is
       * considered to be the default one.
       */
      public MethodType lookupPrimop(SymbolTable stable, String op,
                                     MethodType ctype) {
          MethodType result = null;
          final Vector primop = stable.lookupPrimop(op);
          if (primop != null) {
              final int n = primop.size();
              int minDistance = Integer.MAX_VALUE;
              for (int i = 0; i < n; i++) {
                  final MethodType ptype = (MethodType) primop.elementAt(i);
                  // Skip if different arity
                  if (ptype.argsCount() != ctype.argsCount()) {
                      continue;
                  }
  
                  // The first method with the right arity is the default
                  if (result == null) {
                      result = ptype;             // default method
                  }
  
                  // Check if better than last one found
                  final int distance = ctype.distanceTo(ptype);
                  if (distance < minDistance) {
                      minDistance = distance;
                      result = ptype;
                  }
              }
          }
          return result;
      }
  }
  