/*

 */

/*

 * 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.

 */

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

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

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

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

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

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

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

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

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

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

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.ReferenceType;

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;

/**

 * @author Jacek Ambroziak

 * @author Santiago Pericas-Geertsen

 * @author Morten Jorgensen

 */

class FilterExpr extends Expression {

    /**

     * Primary expression of this filter. I.e., 'e' in '(e)[p1]...[pn]'.

     */

    private Expression   _primary;

    /**

     * Array of predicates in '(e)[p1]...[pn]'.

     */

        _primary = primary;

        _predicates = predicates;

        primary.setParent(this);

    }

    protected Expression getExpr() {

        if (_primary instanceof CastExpr)

            return ((CastExpr)_primary).getExpr();

        else

            return _primary;

    }

    public void setParser(Parser parser) {

        super.setParser(parser);

        _primary.setParser(parser);

        if (_predicates != null) {

            final int n = _predicates.size();

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

                exp.setParser(parser);

                exp.setParent(this);

            }

        }

    }

    public String toString() {

        return "filter-expr(" + _primary + ", " + _predicates + ")";

    }

    /**

     * Type check a FilterParentPath. If the filter is not a node-set add a

     * cast to node-set only if it is of reference type. This type coercion

     * is needed for expressions like $x where $x is a parameter reference.

     * All optimizations are turned off before type checking underlying

     * predicates.

     */

    public Type typeCheck(SymbolTable stable) throws TypeCheckError {

        Type ptype = _primary.typeCheck(stable);

        boolean canOptimize = _primary instanceof KeyCall;

        if (ptype instanceof NodeSetType == false) {

            if (ptype instanceof ReferenceType)  {

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

            }

            else {

                throw new TypeCheckError(this);

            }

        }

        // Type check predicates and turn all optimizations off if appropriate

        int n = _predicates.size();

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

            if (!canOptimize) {

                pred.dontOptimize();

            }

            pred.typeCheck(stable);

        }

        return _type = Type.NodeSet;

    }

    /**

     * Translate a filter expression by pushing the appropriate iterator

     * onto the stack.

     */

    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {

        translateFilterExpr(classGen, methodGen, _predicates == null ? -1 : _predicates.size() - 1);

    }

    private void translateFilterExpr(ClassGenerator classGen,

                                     MethodGenerator methodGen,

                                     int predicateIndex) {

        if (predicateIndex >= 0) {

            translatePredicates(classGen, methodGen, predicateIndex);

        }

        else {

            _primary.translate(classGen, methodGen);

        }

    }

    /**

     * Translate a sequence of predicates. Each predicate is translated

     * by constructing an instance of <code>CurrentNodeListIterator</code>

     * which is initialized from another iterator (recursive call), a

     * filter and a closure (call to translate on the predicate) and "this".

     */

    public void translatePredicates(ClassGenerator classGen,

                                    MethodGenerator methodGen,

                                    int predicateIndex) {

        final ConstantPoolGen cpg = classGen.getConstantPool();

        final InstructionList il = methodGen.getInstructionList();

        // If not predicates left, translate primary expression

        if (predicateIndex < 0) {

            translateFilterExpr(classGen, methodGen, predicateIndex);

        }

        else {

            // Get the next predicate to be translated

            Predicate predicate = (Predicate) _predicates.get(predicateIndex--);

            // Translate the rest of the predicates from right to left

            translatePredicates(classGen, methodGen, predicateIndex);

            if (predicate.isNthPositionFilter()) {

                int nthIteratorIdx = cpg.addMethodref(NTH_ITERATOR_CLASS,

                                       "<init>",

                                       "("+NODE_ITERATOR_SIG+"I)V");

                // Backwards branches are prohibited if an uninitialized object

                // is on the stack by section 4.9.4 of the JVM Specification,

                // 2nd Ed.  We don't know whether this code might contain

                // backwards branches, so we mustn't create the new object unti

                // after we've created the suspect arguments to its constructor

                // Instead we calculate the values of the arguments to the

                // constructor first, store them in temporary variables, create

                // the object and reload the arguments from the temporaries to

                // avoid the problem.

                LocalVariableGen iteratorTemp

                        = methodGen.addLocalVariable("filter_expr_tmp1",

                                         Util.getJCRefType(NODE_ITERATOR_SIG),

                                         null, null);

                iteratorTemp.setStart(

                        il.append(new ASTORE(iteratorTemp.getIndex())));

                predicate.translate(classGen, methodGen);

                LocalVariableGen predicateValueTemp

                        = methodGen.addLocalVariable("filter_expr_tmp2",

                                         Util.getJCRefType("I"),

                                         null, null);

                predicateValueTemp.setStart(

                        il.append(new ISTORE(predicateValueTemp.getIndex())));

                il.append(new NEW(cpg.addClass(NTH_ITERATOR_CLASS)));

                il.append(DUP);

                iteratorTemp.setEnd(

                        il.append(new ALOAD(iteratorTemp.getIndex())));

                predicateValueTemp.setEnd(

                        il.append(new ILOAD(predicateValueTemp.getIndex())));

                il.append(new INVOKESPECIAL(nthIteratorIdx));

            } else {

                    // Translate predicates from right to left

                final int initCNLI = cpg.addMethodref(CURRENT_NODE_LIST_ITERATOR,

                                                      "<init>",

                                                      "("+NODE_ITERATOR_SIG+"Z"+

                                                      CURRENT_NODE_LIST_FILTER_SIG +

                                                      NODE_SIG+TRANSLET_SIG+")V");

                // Backwards branches are prohibited if an uninitialized object is

                // on the stack by section 4.9.4 of the JVM Specification, 2nd Ed.

                // We don't know whether this code might contain backwards branches,

                // so we mustn't create the new object until after we've created

                // the suspect arguments to its constructor.  Instead we calculate

                // the values of the arguments to the constructor first, store them

                // in temporary variables, create the object and reload the

                // arguments from the temporaries to avoid the problem.

                LocalVariableGen nodeIteratorTemp =

                    methodGen.addLocalVariable("filter_expr_tmp1",

                                               Util.getJCRefType(NODE_ITERATOR_SIG),

                                               null, null);

                nodeIteratorTemp.setStart(

                        il.append(new ASTORE(nodeIteratorTemp.getIndex())));

                predicate.translate(classGen, methodGen);

                LocalVariableGen filterTemp =

                    methodGen.addLocalVariable("filter_expr_tmp2",

                                  Util.getJCRefType(CURRENT_NODE_LIST_FILTER_SIG),

                                  null, null);

                filterTemp.setStart(il.append(new ASTORE(filterTemp.getIndex())));

                // Create a CurrentNodeListIterator

                il.append(new NEW(cpg.addClass(CURRENT_NODE_LIST_ITERATOR)));

                il.append(DUP);

                // Initialize CurrentNodeListIterator

                nodeIteratorTemp.setEnd(

                        il.append(new ALOAD(nodeIteratorTemp.getIndex())));

                il.append(ICONST_1);

                filterTemp.setEnd(il.append(new ALOAD(filterTemp.getIndex())));

                il.append(methodGen.loadCurrentNode());

                il.append(classGen.loadTranslet());

                il.append(new INVOKESPECIAL(initCNLI));

            }

        }

    }

}