001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.jexl2.parser;
018
019import org.apache.commons.jexl2.DebugInfo;
020import org.apache.commons.jexl2.JexlEngine;
021import org.apache.commons.jexl2.JexlException;
022
023/**
024 * The base class for parsing, manages the parameter/local variable frame.
025 * @author henri
026 */
027public class JexlParser extends StringParser {
028    /**
029     * The map of named registers aka script parameters.
030     * Each parameter is associated to a register and is materialized as an offset in the registers array used
031     * during evaluation.
032     */
033    protected JexlEngine.Scope frame;
034
035    /**
036     * Sets the frame to use bythis parser.
037     * <p>
038     * This is used to allow parameters to be declared before parsing.
039     * </p>
040     * @param theFrame the register map
041     */
042    public void setFrame(JexlEngine.Scope theFrame) {
043        frame = theFrame;
044    }
045    
046    /**
047     * Gets the frame used by this parser.
048     * <p>
049     * Since local variables create new named registers, it is important to regain access after
050     * parsing to known which / how-many registers are needed.
051     * </p>
052     * @return the named register map
053     */
054    public JexlEngine.Scope getFrame() {
055        return frame;
056    }
057    
058
059    /**
060     * Checks whether an identifier is a local variable or argument, ie stored in a register. 
061     * @param identifier the identifier
062     * @param image the identifier image
063     * @return the image
064     */
065    public String checkVariable(ASTIdentifier identifier, String image) {
066        if (frame != null) {
067            Integer register = frame.getRegister(image);
068            if (register != null) {
069                identifier.setRegister(register.intValue());
070            }
071        }
072        return image;
073    }
074
075    /**
076     * Declares a local variable.
077     * <p>
078     * This method creates an new entry in the named register map.
079     * </p>
080     * @param identifier the identifier used to declare
081     * @param image the variable name
082     */
083    public void declareVariable(ASTVar identifier, String image) {
084        if (frame == null) {
085            frame = new JexlEngine.Scope((String[])null);
086        }
087        Integer register = frame.declareVariable(image);
088        identifier.setRegister(register.intValue());
089        identifier.image = image;
090    }
091
092    /**
093     * Default implementation does nothing but is overriden by generated code.
094     * @param top whether the identifier is beginning an l/r value
095     * @throws ParseException subclasses may throw this 
096     */
097    public void Identifier(boolean top) throws ParseException {
098        // Overriden by generated code
099    }
100
101    final public void Identifier() throws ParseException {
102        Identifier(false);
103    }
104
105    public Token getToken(int index) {
106        return null;
107    }
108
109    void jjtreeOpenNodeScope(JexlNode n) {
110    }
111
112    /**
113     * Ambiguous statement detector.
114     * @param n the node
115     * @throws ParseException 
116     */
117    void jjtreeCloseNodeScope(JexlNode n) throws ParseException {
118        if (n instanceof ASTAmbiguous && n.jjtGetNumChildren() > 0) {
119            DebugInfo dbgInfo = null;
120            Token tok = this.getToken(0);
121            if (tok != null) {
122                dbgInfo = new DebugInfo(tok.image, tok.beginLine, tok.beginColumn);
123            } else {
124                dbgInfo = n.debugInfo();
125            }
126            throw new JexlException.Parsing(dbgInfo, "Ambiguous statement, missing ';' between expressions", null);
127        }
128    }
129}