/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * 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.xalan.internal.xsltc.compiler.util.Type;

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

import java.util.Objects;

/**

 * @author Morten Jorgensen

 * @author Santiago Pericas-Geertsen

 */

class VariableRefBase extends Expression {

    /**

     * A reference to the associated variable.

     */

    protected VariableBase _variable;

    /**

     * A reference to the enclosing expression/instruction for which a

     * closure is needed (Predicate, Number or Sort).

     */

    protected Closure _closure = null;

    public VariableRefBase(VariableBase variable) {

        _variable = variable;

        variable.addReference(this);

    }

    public VariableRefBase() {

        _variable = null;

    }

    /**

     * Returns a reference to the associated variable

     */

    public VariableBase getVariable() {

        return _variable;

    }

    /**

     * If this variable reference is in a top-level element like

     * another variable, param or key, add a dependency between

     * that top-level element and the referenced variable. For

     * example,

     *

     *   <xsl:variable name="x" .../>

     *   <xsl:variable name="y" select="$x + 1"/>

     *

     * and assuming this class represents "$x", add a reference

     * between variable y and variable x.

     */

    public void addParentDependency() {

        SyntaxTreeNode node = this;

        while (node != null && node instanceof TopLevelElement == false) {

            node = node.getParent();

        }

        TopLevelElement parent = (TopLevelElement) node;

        if (parent != null) {

            VariableBase var = _variable;

            if (_variable._ignore) {

                if (_variable instanceof Variable) {

                    var = parent.getSymbolTable()

                                .lookupVariable(_variable._name);

                } else if (_variable instanceof Param) {

                    var = parent.getSymbolTable().lookupParam(_variable._name);

                }

            }

            parent.addDependency(var);

        }

    }

    /**

     * Two variable references are deemed equal if they refer to the

     * same variable.

     */

    @Override

    public boolean equals(Object obj) {

        return obj == this || (obj instanceof VariableRefBase)

            && (_variable == ((VariableRefBase) obj)._variable);

    }

    @Override

    public int hashCode() {

        return Objects.hashCode(this._variable);

    }

    /**

     * Returns a string representation of this variable reference on the

     * format 'variable-ref(<var-name>)'.

     * @return Variable reference description

     */

    @Override

    public String toString() {

        return "variable-ref("+_variable.getName()+'/'+_variable.getType()+')';

    }

    @Override

    public Type typeCheck(SymbolTable stable)

        throws TypeCheckError

    {

        // Returned cached type if available

        if (_type != null) return _type;

        // Find nearest closure to add a variable reference

        if (_variable.isLocal()) {

            SyntaxTreeNode node = getParent();

            do {

                if (node instanceof Closure) {

                    _closure = (Closure) node;

                    break;

                }

                if (node instanceof TopLevelElement) {

                    break;      // way up in the tree

                }

                node = node.getParent();

            } while (node != null);

            if (_closure != null) {

                _closure.addVariable(this);

            }

        }

        // Attempt to get the cached variable type

        _type = _variable.getType();

        // If that does not work we must force a type-check (this is normally

        // only needed for globals in included/imported stylesheets

        if (_type == null) {

            _variable.typeCheck(stable);

            _type = _variable.getType();

        }

        // If in a top-level element, create dependency to the referenced var

        addParentDependency();

        // Return the type of the referenced variable

        return _type;

    }

}