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Jiffle is a raster algebra language that can be used to create new images from logical and mathematical expressions involving source images and user defined variables. It is intended to let users concentrate on algorithms rather than tedious boiler-plate code.

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/*
 * Copyright 2011 Michael Bedward
 * 
 * This file is part of jai-tools.
 *
 * jai-tools is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the 
 * License, or (at your option) any later version.
 *
 * jai-tools is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public 
 * License along with jai-tools.  If not, see .
 * 
 */

package jaitools.jiffle.parser;

import jaitools.CollectionFactory;
import java.util.Collections;
import java.util.List;

/**
 * Stores symbols in a Jiffle script at a single scope level. Used during
 * script compilation.
 * 
 * @author Michael Bedward
 * @since 1.1
 * @version $Id: SymbolScope.java 1428 2011-02-18 06:43:31Z michael.bedward $
 */
public class SymbolScope {

    private final String name;
    private final List symbols;

    /**
     * Creates a new scope.
     * 
     * @param name a scope label
     */
    public SymbolScope(String name) {
        this.name = name;
        this.symbols = CollectionFactory.list();
    }

    /**
     * Gets the scope label.
     * 
     * @return scope label
     */
    public String getName() {
        return name;
    }

    /**
     * Gets the list of symbols in this scope. The list
     * is returned as an unmodifiable view.
     * 
     * @return list of symbols
     */
    public List getSymbols() {
        return Collections.unmodifiableList(symbols);
    }
    
    /**
     * Tests if this scope is empty.
     * 
     * @return {@code true} if there are no symbols; {@code false} otherwise
     */
    public boolean isEmpty() {
        return symbols.isEmpty();
    }
    
    /**
     * Gets the number of symbols in this scope.
     * 
     * @return number of symbols
     */
    public int size() {
        return symbols.size();
    }
    
    /**
     * Adds a symbol to this scope.
     * 
     * @param symbol the symbol
     * @throws IllegalArgumentException if {@code symbol} is {@code null}
     */
    public void add(Symbol symbol) {
        if (symbol == null) {
            throw new IllegalArgumentException("symbol must not be null");
        }
        symbols.add(symbol);
    }

    /**
     * Tests if this scope contains a symbol with the given name.
     * 
     * @param name symbol name
     * @return {@code true} if a symbol with this name is found; 
     *         {@code false} otherwise
     */
    public boolean hasSymbolNamed(String name) {
        return findSymbolNamed(name) != null;
    }
    
    /**
     * Gets the symbol with the given name if one exists.
     * 
     * @param name symbol name
     * @return the symbol or {@code null} if not match was found
     */
    public Symbol findSymbolNamed(String name) {
        for (Symbol s : symbols) {
            if (s.getName().equals(name)) {
                return s;
            }
        }
        return null;
    }
}