/*

 * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.

 */

/*

 * 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: ForEach.java,v 1.2.4.1 2005/09/01 15:23:46 pvedula Exp $

 */

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

import com.sun.org.apache.bcel.internal.generic.BranchHandle;

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

import com.sun.org.apache.bcel.internal.generic.GOTO;

import com.sun.org.apache.bcel.internal.generic.IFGT;

import com.sun.org.apache.bcel.internal.generic.InstructionHandle;

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

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

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

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

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

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

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

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

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

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

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

import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;

/**

 * @author Jacek Ambroziak

 * @author Santiago Pericas-Geertsen

 * @author Morten Jorgensen

 * @LastModified: Oct 2017

 */

final class ForEach extends Instruction {

    private Expression _select;

    private Type       _type;

    public void display(int indent) {

        indent(indent);

        Util.println("ForEach");

        indent(indent + IndentIncrement);

        Util.println("select " + _select.toString());

        displayContents(indent + IndentIncrement);

    }

    public void parseContents(Parser parser) {

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

        parseChildren(parser);

        // make sure required attribute(s) have been set

        if (_select.isDummy()) {

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

        }

    }

    public Type typeCheck(SymbolTable stable) throws TypeCheckError {

        _type = _select.typeCheck(stable);

        if (_type instanceof ReferenceType || _type instanceof NodeType) {

            _select = new CastExpr(_select, Type.NodeSet);

            typeCheckContents(stable);

            return Type.Void;

        }

        if (_type instanceof NodeSetType||_type instanceof ResultTreeType) {

            typeCheckContents(stable);

            return Type.Void;

        }

        throw new TypeCheckError(this);

    }

    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {

        final ConstantPoolGen cpg = classGen.getConstantPool();

        final InstructionList il = methodGen.getInstructionList();

        // Save current node and current iterator on the stack

        il.append(methodGen.loadCurrentNode());

        il.append(methodGen.loadIterator());

        // Collect sort objects associated with this instruction

        final List<Sort> sortObjects = new ArrayList<>();

        Iterator<SyntaxTreeNode> children = elements();

        while (children.hasNext()) {

            final SyntaxTreeNode child = children.next();

            if (child instanceof Sort) {

                sortObjects.add((Sort)child);

            }

        }

        if ((_type != null) && (_type instanceof ResultTreeType)) {

            // Store existing DOM on stack - must be restored when loop is done

            il.append(methodGen.loadDOM());

            // <xsl:sort> cannot be applied to a result tree - issue warning

            if (sortObjects.size() > 0) {

                ErrorMsg msg = new ErrorMsg(ErrorMsg.RESULT_TREE_SORT_ERR,this);

                getParser().reportError(WARNING, msg);

            }

            // Put the result tree on the stack (DOM)

            _select.translate(classGen, methodGen);

            // Get an iterator for the whole DOM - excluding the root node

            _type.translateTo(classGen, methodGen, Type.NodeSet);

            // Store the result tree as the default DOM

            il.append(SWAP);

            il.append(methodGen.storeDOM());

        }

        else {

            // Compile node iterator

            if (sortObjects.size() > 0) {

                Sort.translateSortIterator(classGen, methodGen,

                                           _select, sortObjects);

            }

            else {

                _select.translate(classGen, methodGen);

            }

            if (_type instanceof ReferenceType == false) {

                il.append(methodGen.loadContextNode());

                il.append(methodGen.setStartNode());

            }

        }

        // Overwrite current iterator

        il.append(methodGen.storeIterator());

        // Give local variables (if any) default values before starting loop

        initializeVariables(classGen, methodGen);

        final BranchHandle nextNode = il.append(new GOTO(null));

        final InstructionHandle loop = il.append(NOP);

        translateContents(classGen, methodGen);

        nextNode.setTarget(il.append(methodGen.loadIterator()));

        il.append(methodGen.nextNode());

        il.append(DUP);

        il.append(methodGen.storeCurrentNode());

        il.append(new IFGT(loop));

        // Restore current DOM (if result tree was used instead for this loop)

        if ((_type != null) && (_type instanceof ResultTreeType)) {

            il.append(methodGen.storeDOM());

        }

        // Restore current node and current iterator from the stack

        il.append(methodGen.storeIterator());

        il.append(methodGen.storeCurrentNode());

    }

    /**

     * The code that is generated by nested for-each loops can appear to some

     * JVMs as if it is accessing un-initialized variables. We must add some

     * code that pushes the default variable value on the stack and pops it

     * into the variable slot. This is done by the Variable.initialize()

     * method. The code that we compile for this loop looks like this:

     *

     *           initialize iterator

     *           initialize variables <-- HERE!!!

     *           goto   Iterate

     *  Loop:    :

     *           : (code for <xsl:for-each> contents)

     *           :

     *  Iterate: node = iterator.next();

     *           if (node != END) goto Loop

     */

    public void initializeVariables(ClassGenerator classGen,

                                   MethodGenerator methodGen) {

        final int n = elementCount();

        for (int i = 0; i < n; i++) {

            final Object child = getContents().get(i);

            if (child instanceof Variable) {

                Variable var = (Variable)child;

                var.initialize(classGen, methodGen);

            }

        }

    }

}