/*
 * 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 org.apache.bcel.verifier.statics;


import java.util.Hashtable;

import org.apache.bcel.generic.Type;
import org.apache.bcel.verifier.exc.LocalVariableInfoInconsistentException;

A utility class holding the information about
the name and the type of a local variable in
a given slot (== index). This information
often changes in course of byte code offsets.
/**
 * A utility class holding the information about
 * the name and the type of a local variable in
 * a given slot (== index). This information
 * often changes in course of byte code offsets.
 */
public class LocalVariableInfo{

    
The types database. KEY: String representing the offset integer. /** The types database. KEY: String representing the offset integer. */
    private final Hashtable<String, Type> types = new Hashtable<>();

    
The names database. KEY: String representing the offset integer. /** The names database. KEY: String representing the offset integer. */
    private final Hashtable<String, String> names = new Hashtable<>();

    
Adds a name of a local variable and a certain slot to our 'names'
(Hashtable) database.
/**
     * Adds a name of a local variable and a certain slot to our 'names'
     * (Hashtable) database.
     */
    private void setName(final int offset, final String name) {
        names.put(Integer.toString(offset), name);
    }

    
Adds a type of a local variable and a certain slot to our 'types'
(Hashtable) database.
/**
     * Adds a type of a local variable and a certain slot to our 'types'
     * (Hashtable) database.
     */
    private void setType(final int offset, final Type t) {
        types.put(Integer.toString(offset), t);
    }

    
Returns the type of the local variable that uses this local variable slot at the given bytecode offset. Care for
legal bytecode offsets yourself, otherwise the return value might be wrong. May return 'null' if nothing is known
about the type of this local variable slot at the given bytecode offset.
Params:
offset – bytecode offset.
Returns:
the type of the local variable that uses this local variable slot at the given bytecode offset./**
     * Returns the type of the local variable that uses this local variable slot at the given bytecode offset. Care for
     * legal bytecode offsets yourself, otherwise the return value might be wrong. May return 'null' if nothing is known
     * about the type of this local variable slot at the given bytecode offset.
     *
     * @param offset bytecode offset.
     * @return the type of the local variable that uses this local variable slot at the given bytecode offset.
     */
    public Type getType(final int offset) {
        return types.get(Integer.toString(offset));
    }

    
Returns the name of the local variable that uses this local variable slot at the given bytecode offset. Care for
legal bytecode offsets yourself, otherwise the return value might be wrong. May return 'null' if nothing is known
about the type of this local variable slot at the given bytecode offset.
Params:
offset – bytecode offset.
Returns:
the name of the local variable that uses this local variable slot at the given bytecode offset./**
     * Returns the name of the local variable that uses this local variable slot at the given bytecode offset. Care for
     * legal bytecode offsets yourself, otherwise the return value might be wrong. May return 'null' if nothing is known
     * about the type of this local variable slot at the given bytecode offset.
     *
     * @param offset bytecode offset.
     * @return the name of the local variable that uses this local variable slot at the given bytecode offset.
     */
    public String getName(final int offset) {
        return names.get(Integer.toString(offset));
    }

    
Adds some information about this local variable (slot).
Params:
name – variable name
startPc – Range in which the variable is valid.
length – length of ...
type – variable type
Throws:
LocalVariableInfoInconsistentException – if the new information conflicts
        with already gathered information./**
     * Adds some information about this local variable (slot).
     *
     * @param name variable name
     * @param startPc Range in which the variable is valid.
     * @param length length of ...
     * @param type variable type
     *
     * @throws LocalVariableInfoInconsistentException if the new information conflicts
     *         with already gathered information.
     */
    public void add(final String name, final int startPc, final int length, final Type type)
            throws LocalVariableInfoInconsistentException {
        for (int i = startPc; i <= startPc + length; i++) { // incl/incl-notation!
            add(i, name, type);
        }
    }

    
Adds information about name and type for a given offset.
Throws:
LocalVariableInfoInconsistentException – if the new information conflicts
        with already gathered information./**
     * Adds information about name and type for a given offset.
     *
     * @throws LocalVariableInfoInconsistentException if the new information conflicts
     *         with already gathered information.
     */
    private void add(final int offset, final String name, final Type t) throws LocalVariableInfoInconsistentException {
        if (getName(offset) != null) {
            if (!getName(offset).equals(name)) {
                throw new LocalVariableInfoInconsistentException("At bytecode offset '" + offset
                        + "' a local variable has two different names: '" + getName(offset) + "' and '" + name + "'.");
            }
        }
        if (getType(offset) != null) {
            if (!getType(offset).equals(t)) {
                throw new LocalVariableInfoInconsistentException("At bytecode offset '" + offset
                        + "' a local variable has two different types: '" + getType(offset) + "' and '" + t + "'.");
            }
        }
        setName(offset, name);
        setType(offset, t);
    }
}