Tutoriais - Linguagens Formais e Autômatos
Tutoriais
Linguagens Formais e Autômatos

/*************************************************************************
 * Copyright (C) 2009/2024 - Cristiano Lehrer (cristiano@ybadoo.com.br)  *
 *                  Ybadoo - Solucoes em Software Livre (ybadoo.com.br)  *
 *                                                                       *
 * Permission is granted to copy, distribute and/or modify this document *
 * under the terms of the GNU Free Documentation License, Version 1.3 or *
 * any later version published by the  Free Software Foundation; with no *
 * Invariant Sections,  no Front-Cover Texts, and no Back-Cover Texts. A *
 * A copy of the  license is included in  the section entitled "GNU Free *
 * Documentation License".                                               *
 *                                                                       *
 * Ubuntu 16.10 (GNU/Linux 4.8.0-39-generic)                             *
 * OpenJDK Version "1.8.0_121"                                           *
 * OpenJDK 64-Bit Server VM (build 25.121-b13, mixed mode)               *
 *************************************************************************/

package com.ybadoo.tutoriais.lfa.tutorial01.topico07.exercicio01;

import java.util.LinkedList;
import java.util.List;

/**
 * Classe responsavel pela geracao dos prefixos da palavra
 */
public class Prefix
{
  /**
   * Lista de prefixos
   */
  private List<String> prefixes;

  /**
   * Palavra
   */
  private String word;

  /**
   * Construtor para inicializar a palavra
   *
   * @param word palavra
   */
  public Prefix(String word)
  {
    this.word = word;

    prefixes = new LinkedList<String>();

    prefixes.add("&");

    for(int index = 1; index <= word.length(); index++)
    {
      prefixes.add(word.substring(0, index));
    }
  }

  /**
   * Retornar true se o prefixo fornecido for um prefixo da palavra
   *
   * @param prefix prefixo fornecido
   * @return true se o prefixo fornecido for um prefixo da palavra
   */
  public boolean isPrefix(String prefix)
  {
    return prefixes.contains(prefix);
  }

  /**
   * Retornar a lista de prefixos
   *
   * @return lista de prefixos
   */
  public String[] list()
  {
    return prefixes.toArray(new String[0]);
  }

  /**
   * Retornar a quantidade de prefixos
   *
   * @return quantidade de prefixos
   */
  public int size()
  {
    return prefixes.size();
  }

  /* (non-Javadoc)
   * @see java.lang.Object#toString()
   */
  @Override
  public String toString()
  {
    StringBuilder out = new StringBuilder();

    out.append("{");

    for(String prefix : prefixes)
    {
      if(prefix.length() != word.length())
      {
        out.append(prefix).append(", ");
      }
      else
      {
        out.append(prefix);
      }
    }

    out.append("}");

    return out.toString();
  }
}

/*************************************************************************
 * Copyright (C) 2009/2024 - Cristiano Lehrer (cristiano@ybadoo.com.br)  *
 *                  Ybadoo - Solucoes em Software Livre (ybadoo.com.br)  *
 *                                                                       *
 * Permission is granted to copy, distribute and/or modify this document *
 * under the terms of the GNU Free Documentation License, Version 1.3 or *
 * any later version published by the  Free Software Foundation; with no *
 * Invariant Sections,  no Front-Cover Texts, and no Back-Cover Texts. A *
 * A copy of the  license is included in  the section entitled "GNU Free *
 * Documentation License".                                               *
 *                                                                       *
 * Ubuntu 16.10 (GNU/Linux 4.8.0-39-generic)                             *
 * OpenJDK Version "1.8.0_121"                                           *
 * OpenJDK 64-Bit Server VM (build 25.121-b13, mixed mode)               *
 *************************************************************************/

package com.ybadoo.tutoriais.lfa.tutorial01.topico07.exercicio01;

import java.util.Scanner;

/**
 * Classe responsavel pela execucao da classe Prefix
 */
public class Application
{
  /**
   * Metodo principal da linguagem de programacao Java
   *
   * @param args argumentos da linha de comando (nao utilizado)
   */
  public static void main(String[] args)
  {
    Scanner scanner = new Scanner(System.in);

    System.out.print("Forneça a palavra desejada: ");
    String word = scanner.nextLine().trim();

    Prefix prefix = new Prefix(word);

    System.out.println("Observação: \"&\" representa a palavra vazia");
    System.out.print("Prefixos: ");
    System.out.println(prefix);

    scanner.close();
  }
}