emit.java

我开发的一个用java语言实现的编译器,内含词法分析器,语法分析器,而且可以实现中间代码生成.用到了SLR算法和LR(1)算法

					     act.kind() + " found in parse table");
		}
	    }

	  /* now we know how big to make the row */
	  action_table[i] = new short[nentries + 2];
	  System.arraycopy(temp_table, 0, action_table[i], 0, nentries);

	  /* finish off the row with a default entry */
	  action_table[i][nentries++] = -1;
	  if (row.default_reduce != -1)
	    action_table[i][nentries++] = (short) (-(row.default_reduce+1));
	  else
	    action_table[i][nentries++] = 0;
	}

      /* finish off the init of the table */
      out.println();
      out.println("  /** Parse-action table. */");
      out.println("  protected static final short[][] _action_table = "); 
      out.print  ("    unpackFromStrings(");
      do_table_as_string(out, action_table);
      out.println(");");

      /* do the public accessor method */
      out.println();
      out.println("  /** Access to parse-action table. */");
      out.println("  public short[][] action_table() {return _action_table;}");

      action_table_time = System.currentTimeMillis() - start_time;
    }

  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

  /** Emit the reduce-goto table. 
   * @param out     stream to produce output on.
   * @param red_tab the internal representation of the reduce-goto table.
   */
  protected static void do_reduce_table(
    PrintWriter out, 
    parse_reduce_table red_tab)
    {
      lalr_state       goto_st;
      parse_action     act;

      long start_time = System.currentTimeMillis();

      /* collect values for reduce-goto table */
      short[][] reduce_goto_table = new short[red_tab.num_states()][];
      /* do each row of the reduce-goto table */
      for (int i=0; i<red_tab.num_states(); i++)
	{
	  /* make temporary table for the row. */
	  short[] temp_table = new short[2*red_tab.under_state[i].size()];
	  int nentries = 0;
	  /* do each entry in the row */
	  for (int j=0; j<red_tab.under_state[i].size(); j++)
	    {
	      /* get the entry */
	      goto_st = red_tab.under_state[i].under_non_term[j];

	      /* if we have none, skip it */
	      if (goto_st != null)
		{
		  /* make entries for the index and the value */
		  temp_table[nentries++] = (short) j;
		  temp_table[nentries++] = (short) goto_st.index();
		}
	    }
	  /* now we know how big to make the row. */
	  reduce_goto_table[i] = new short[nentries+2];
	  System.arraycopy(temp_table, 0, reduce_goto_table[i], 0, nentries);

	  /* end row with default value */
	  reduce_goto_table[i][nentries++] = -1;
	  reduce_goto_table[i][nentries++] = -1;
	}

      /* emit the table. */
      out.println();
      out.println("  /** <code>reduce_goto</code> table. */");
      out.println("  protected static final short[][] _reduce_table = "); 
      out.print  ("    unpackFromStrings(");
      do_table_as_string(out, reduce_goto_table);
      out.println(");");

      /* do the public accessor method */
      out.println();
      out.println("  /** Access to <code>reduce_goto</code> table. */");
      out.println("  public short[][] reduce_table() {return _reduce_table;}");
      out.println();

      goto_table_time = System.currentTimeMillis() - start_time;
    }

  // print a string array encoding the given short[][] array.
  protected static void do_table_as_string(PrintWriter out, short[][] sa) {
    out.println("new String[] {");
    out.print("    \"");
    int nchar=0, nbytes=0;
    nbytes+=do_escaped(out, (char)(sa.length>>16));
    nchar  =do_newline(out, nchar, nbytes);
    nbytes+=do_escaped(out, (char)(sa.length&0xFFFF));
    nchar  =do_newline(out, nchar, nbytes);
    for (int i=0; i<sa.length; i++) {
	nbytes+=do_escaped(out, (char)(sa[i].length>>16));
	nchar  =do_newline(out, nchar, nbytes);
	nbytes+=do_escaped(out, (char)(sa[i].length&0xFFFF));
	nchar  =do_newline(out, nchar, nbytes);
	for (int j=0; j<sa[i].length; j++) {
	  // contents of string are (value+2) to allow for common -1, 0 cases
	  // (UTF-8 encoding is most efficient for 0<c<0x80)
	  nbytes+=do_escaped(out, (char)(2+sa[i][j]));
	  nchar  =do_newline(out, nchar, nbytes);
	}
    }
    out.print("\" }");
  }
  // split string if it is very long; start new line occasionally for neatness
  protected static int do_newline(PrintWriter out, int nchar, int nbytes) {
    if (nbytes > 65500)  { out.println("\", "); out.print("    \""); }
    else if (nchar > 11) { out.println("\" +"); out.print("    \""); }
    else return nchar+1;
    return 0;
  }
  // output an escape sequence for the given character code.
  protected static int do_escaped(PrintWriter out, char c) {
    StringBuffer escape = new StringBuffer();
    if (c <= 0xFF) {
      escape.append(Integer.toOctalString(c));
      while(escape.length() < 3) escape.insert(0, '0');
    } else {
      escape.append(Integer.toHexString(c));
      while(escape.length() < 4) escape.insert(0, '0');
      escape.insert(0, 'u');
    }
    escape.insert(0, '\\');
    out.print(escape.toString());

    // return number of bytes this takes up in UTF-8 encoding.
    if (c == 0) return 2;
    if (c >= 0x01 && c <= 0x7F) return 1;
    if (c >= 0x80 && c <= 0x7FF) return 2;
    return 3;
  }

  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

  /** Emit the parser subclass with embedded tables. 
   * @param out             stream to produce output on.
   * @param action_table    internal representation of the action table.
   * @param reduce_table    internal representation of the reduce-goto table.
   * @param start_st        start state of the parse machine.
   * @param start_prod      start production of the grammar.
   * @param compact_reduces do we use most frequent reduce as default?
   * @param suppress_scanner should scanner be suppressed for compatibility?
   */
  public static void parser(
    PrintWriter        out, 
    parse_action_table action_table,
    parse_reduce_table reduce_table,
    int                start_st,
    production         start_prod,
    boolean            compact_reduces,
    boolean            suppress_scanner)
    throws internal_error
    {
      long start_time = System.currentTimeMillis();

      /* top of file */
      out.println();
      out.println("//----------------------------------------------------"); 
      out.println("// The following code was generated by " + 
							version.title_str);
      out.println("// " + new Date());
      out.println("//----------------------------------------------------"); 
      out.println();
      emit_package(out);

      /* user supplied imports */
      for (int i = 0; i < import_list.size(); i++)
	out.println("import " + import_list.elementAt(i) + ";");

      /* class header */
      out.println();
      out.println("/** "+version.title_str+" generated parser.");
      out.println("  * @version " + new Date());
      out.println("  */");
      out.println("public class " + parser_class_name + 
		  " extends java_cup.runtime.lr_parser {");

      /* constructors [CSA/davidm, 24-jul-99] */
      out.println();
      out.println("  /** Default constructor. */");
      out.println("  public " + parser_class_name + "() {super();}");
      if (!suppress_scanner) {
	  out.println();
	  out.println("  /** Constructor which sets the default scanner. */");
	  out.println("  public " + parser_class_name + 
		      "(java_cup.runtime.Scanner s) {super(s);}");
      }

      /* emit the various tables */
      emit_production_table(out);
      do_action_table(out, action_table, compact_reduces);
      do_reduce_table(out, reduce_table);

      /* instance of the action encapsulation class */
      out.println("  /** Instance of action encapsulation class. */");
      out.println("  protected " + pre("actions") + " action_obj;");
      out.println();

      /* action object initializer */
      out.println("  /** Action encapsulation object initializer. */");
      out.println("  protected void init_actions()");
      out.println("    {");
      out.println("      action_obj = new " + pre("actions") + "(this);");
      out.println("    }");
      out.println();

      /* access to action code */
      out.println("  /** Invoke a user supplied parse action. */");
      out.println("  public java_cup.runtime.Symbol do_action(");
      out.println("    int                        act_num,");
      out.println("    java_cup.runtime.lr_parser parser,");
      out.println("    java.util.Stack            stack,");
      out.println("    int                        top)");
      out.println("    throws java.lang.Exception");
      out.println("  {");
      out.println("    /* call code in generated class */");
      out.println("    return action_obj." + pre("do_action(") +
                  "act_num, parser, stack, top);");
      out.println("  }");
      out.println("");


      /* method to tell the parser about the start state */
      out.println("  /** Indicates start state. */");
      out.println("  public int start_state() {return " + start_st + ";}");

      /* method to indicate start production */
      out.println("  /** Indicates start production. */");
      out.println("  public int start_production() {return " + 
		     start_production.index() + ";}");
      out.println();

      /* methods to indicate EOF and error symbol indexes */
      out.println("  /** <code>EOF</code> Symbol index. */");
      out.println("  public int EOF_sym() {return " + terminal.EOF.index() + 
					  ";}");
      out.println();
      out.println("  /** <code>error</code> Symbol index. */");
      out.println("  public int error_sym() {return " + terminal.error.index() +
					  ";}");
      out.println();

      /* user supplied code for user_init() */
      if (init_code != null)
	{
          out.println();
	  out.println("  /** User initialization code. */");
	  out.println("  public void user_init() throws java.lang.Exception");
	  out.println("    {");
	  out.println(init_code);
	  out.println("    }");
	}

      /* user supplied code for scan */
      if (scan_code != null)
	{
          out.println();
	  out.println("  /** Scan to get the next Symbol. */");
	  out.println("  public java_cup.runtime.Symbol scan()");
	  out.println("    throws java.lang.Exception");
	  out.println("    {");
	  out.println(scan_code);
	  out.println("    }");
	}

      /* user supplied code */
      if (parser_code != null)
	{
	  out.println();
          out.println(parser_code);
	}

      /* end of class */
      out.println("}");

      /* put out the action code class */
      emit_action_code(out, start_prod);

      parser_time = System.currentTimeMillis() - start_time;
    }

    /*-----------------------------------------------------------*/
}