package littlecompiler;
/*解釋器模式有點(diǎn)像演算法中的個(gè)別擊破解釋的方式，對(duì)每一個(gè)父節(jié)點(diǎn)
 我們剖析出其中的子節(jié)點(diǎn)的組合，然后再交由子節(jié)點(diǎn)剖析,直接剖析到終端節(jié)點(diǎn)為止。
 讓我們做一個(gè)小小的程式解釋器,可以將自定義文法程式文件解釋執(zhí)行。程式的關(guān)鍵字只有PROGRAM、PRINT、SPACE、BREAK、LINEBREAK、REPEAT、END。
 PROGRAM是程式的開始，END是結(jié)尾。簡單的例子為:
    PROGRAM
   PRINT dog SPACE
   PRINT is SPACE
   PRINT an SPACE
   PRINT animai
   END
程序會(huì)印出"dog is an animal",再一個(gè)例子:
 PROGRAM
    REPEAT 2
        LINEBREAK
        PRINT dog
        BREAK
    END
 END
程序會(huì)印出
 ------------------------------
 dog
 ------------------------------
 dog


 */
import java.util.*;
import java.io.*;
public class Client {
  public static void main (String[] args) {
    try {
      BufferedReader reader = new BufferedReader (new FileReader (args[ 0 ]));
      String text;
      while ( (text = reader.readLine ()) != null) {
        System.out.println ("text = \"" + text + "\"");
        Node node = new ProgramNode ();
        node.parse (new Context (text));
        System.out.println ("node = " + node);
        node.execute();
      }
    }
    catch (ArrayIndexOutOfBoundsException e) {
      System.err.println ("Usage: java Main yourprogram.txt");
    }
    catch (Exception e) {
      e.printStackTrace ();
    }
  }
}