Java StreamTokenizer.pushBack方法代码示例

import java.io.StreamTokenizer; //导入方法依赖的package包/类
/**
 * Skips the back slash in the next token if it's followed by a new line.  
 */
private static void skipBackSlash(StreamTokenizer tokenizer) throws IOException
{
	tokenizer.ordinaryChar('\\');
	if (tokenizer.nextToken() == '\\')
	{
		if (tokenizer.nextToken() != StreamTokenizer.TT_EOL)
		{
			throw new IncorrectFormatException("Expected new line after \\ character");
		}
	}
	else
	{
		tokenizer.pushBack();
	}
	tokenizer.wordChars('\\', '\\');
}
 

import java.io.StreamTokenizer; //导入方法依赖的package包/类
/** Skips all tokens before next end of line (EOL). */
public static void waitForEOL(StreamTokenizer tokenizer) throws IOException {
	// skip everything until EOL
	while (tokenizer.nextToken() != StreamTokenizer.TT_EOL) {
	}
	;
	tokenizer.pushBack();
}
 

import java.io.StreamTokenizer; //导入方法依赖的package包/类
/**
 * Reads and skips all tokens before next end of line token.
 *
 * @throws IOException in case something goes wrong
 */
private void readTillEOL(StreamTokenizer tokenizer) throws IOException {
    while (tokenizer.nextToken() != StreamTokenizer.TT_EOL) {
    }

    tokenizer.pushBack();
}
 

import java.io.StreamTokenizer; //导入方法依赖的package包/类
private static Expr parseBuiltInPredicate(String lhs, StreamTokenizer scan) throws DatalogException {
    try {
        String operator;
        scan.nextToken();
        if(scan.ttype == StreamTokenizer.TT_WORD) {
            // At some point I was going to have "eq" and "ne" for string comparisons, but it wasn't a good idea.
            operator = scan.sval;
        } else {
            operator = Character.toString((char)scan.ttype);
            scan.nextToken();
            if(scan.ttype == '=' || scan.ttype == '>') {
                operator = operator + Character.toString((char)scan.ttype);
            } else {
                scan.pushBack();
            }
        }

        if(!validOperators.contains(operator)) {
            throw new DatalogException("Invalid operator '" + operator + "'");
        }

        String rhs = null;
        scan.nextToken();
        if(scan.ttype == StreamTokenizer.TT_WORD) {
            rhs = scan.sval;
        } else if(scan.ttype == '"' || scan.ttype == '\'') {
            rhs = scan.sval;
        } else if(scan.ttype == StreamTokenizer.TT_NUMBER) {
            rhs = numberToString(scan.nval);
        } else {
            throw new DatalogException("[line " + scan.lineno() + "] Right hand side of expression expected");
        }

        return new Expr(operator, lhs, rhs);

    } catch (IOException e) {
        throw new DatalogException(e);
    }
}
 

import java.io.StreamTokenizer; //导入方法依赖的package包/类
/**
   * Executes all the statements in a file/string or another object wrapped by a {@link java.io.Reader}.
   * <p>
   * An optional {@link QueryOutput} object can be supplied as a parameter to output the results of multiple queries.
   * </p><p>
   * This is how to interpret the returned {@code Collection<Map<String, String>>}, assuming you store it in a variable
   * called {@code answers}: 
* </p>
   * <ul>
* <li> If {@code answers} is {@code null}, the statement didn't produce any results; i.e. it was a fact or a rule, not a query.
* <li> If {@code answers} is empty, then it was a query that doesn't have any answers, so the output is "No."
* <li> If {@code answers} is a list of empty maps, then it was the type of query that only wanted a yes/no
*     answer, like {@code siblings(alice,bob)?} and the answer is "Yes."
* <li> Otherwise {@code answers} is a list of all bindings that satisfy the query.
* </ul>
   * @param reader The reader from which the statements are read.
   * @param output The object through which output should be written. Can be {@code null} in which case no output will be written.
   * @return The answer of the last statement in the file, as a Collection of variable mappings.
   * @throws DatalogException on syntax and I/O errors encountered while executing. 
   * @see QueryOutput
   */
  public Collection<Map<String, String>> executeAll(Reader reader, QueryOutput output) throws DatalogException {
      try {
          StreamTokenizer scan = getTokenizer(reader);
          
          // Tracks the last query's answers
          Collection<Map<String, String>> answers = null;
          scan.nextToken();
          while(scan.ttype != StreamTokenizer.TT_EOF) {
              scan.pushBack();
              answers = executeSingleStatement(scan, reader, output);
              scan.nextToken();
          }            
          return answers;
      } catch (IOException e) {
          throw new DatalogException(e);
      }
  }
 

import java.io.StreamTokenizer; //导入方法依赖的package包/类
protected void nodeStmt(StreamTokenizer tk, final int nindex)
  throws Exception {
  tk.nextToken();

  GraphNode temp = m_nodes.get(nindex);

  if (tk.ttype == ']' || tk.ttype == StreamTokenizer.TT_EOF) {
    return;
  } else if (tk.ttype == StreamTokenizer.TT_WORD) {

    if (tk.sval.equalsIgnoreCase("label")) {

      tk.nextToken();
      if (tk.ttype == '=') {
        tk.nextToken();
        if (tk.ttype == StreamTokenizer.TT_WORD || tk.ttype == '"') {
          temp.lbl = tk.sval;
        } else {
          System.err.println("couldn't find label at line " + tk.lineno());
          tk.pushBack();
        }
      } else {
        System.err.println("couldn't find label at line " + tk.lineno());
        tk.pushBack();
      }
    }

    else if (tk.sval.equalsIgnoreCase("color")) {

      tk.nextToken();
      if (tk.ttype == '=') {
        tk.nextToken();
        if (tk.ttype == StreamTokenizer.TT_WORD || tk.ttype == '"') {
          ;
        } else {
          System.err.println("couldn't find color at line " + tk.lineno());
          tk.pushBack();
        }
      } else {
        System.err.println("couldn't find color at line " + tk.lineno());
        tk.pushBack();
      }
    }

    else if (tk.sval.equalsIgnoreCase("style")) {

      tk.nextToken();
      if (tk.ttype == '=') {
        tk.nextToken();
        if (tk.ttype == StreamTokenizer.TT_WORD || tk.ttype == '"') {
          ;
        } else {
          System.err.println("couldn't find style at line " + tk.lineno());
          tk.pushBack();
        }
      } else {
        System.err.println("couldn't find style at line " + tk.lineno());
        tk.pushBack();
      }
    }
  }
  nodeStmt(tk, nindex);
}
 

import java.io.StreamTokenizer; //导入方法依赖的package包/类
protected void edgeStmt(StreamTokenizer tk, final int nindex)
  throws Exception {
  tk.nextToken();

  GraphEdge e = null;
  if (tk.ttype == '>') {
    tk.nextToken();
    if (tk.ttype == '{') {
      while (true) {
        tk.nextToken();
        if (tk.ttype == '}') {
          break;
        } else {
          nodeID(tk);
          e = new GraphEdge(nindex, m_nodes.indexOf(new GraphNode(tk.sval,
            null)), DIRECTED);
          if (m_edges != null && !(m_edges.contains(e))) {
            m_edges.add(e);
            // System.out.println("Added edge from "+
            // ((GraphNode)(m_nodes.get(nindex))).ID+
            // " to "+
            // ((GraphNode)(m_nodes.get(e.dest))).ID);
          }
        }
      }
    } else {
      nodeID(tk);
      e = new GraphEdge(nindex,
        m_nodes.indexOf(new GraphNode(tk.sval, null)), DIRECTED);
      if (m_edges != null && !(m_edges.contains(e))) {
        m_edges.add(e);
        // System.out.println("Added edge from "+
        // ((GraphNode)(m_nodes.get(nindex))).ID+" to "+
        // ((GraphNode)(m_nodes.get(e.dest))).ID);
      }
    }
  } else if (tk.ttype == '-') {
    System.err.println("Error at line " + tk.lineno()
      + ". Cannot deal with undirected edges");
    if (tk.ttype == StreamTokenizer.TT_WORD) {
      tk.pushBack();
    }
    return;
  } else {
    System.err.println("Error at line " + tk.lineno() + " in edgeStmt");
    if (tk.ttype == StreamTokenizer.TT_WORD) {
      tk.pushBack();
    }
    return;
  }

  tk.nextToken();

  if (tk.ttype == '[') {
    edgeAttrib(tk, e);
  } else {
    tk.pushBack();
  }
}
 

import java.io.StreamTokenizer; //导入方法依赖的package包/类
protected void edgeAttrib(StreamTokenizer tk, final GraphEdge e)
  throws Exception {
  tk.nextToken();

  if (tk.ttype == ']' || tk.ttype == StreamTokenizer.TT_EOF) {
    return;
  } else if (tk.ttype == StreamTokenizer.TT_WORD) {

    if (tk.sval.equalsIgnoreCase("label")) {

      tk.nextToken();
      if (tk.ttype == '=') {
        tk.nextToken();
        if (tk.ttype == StreamTokenizer.TT_WORD || tk.ttype == '"') {
          System.err.println("found label " + tk.sval);// e.lbl = tk.sval;
        } else {
          System.err.println("couldn't find label at line " + tk.lineno());
          tk.pushBack();
        }
      } else {
        System.err.println("couldn't find label at line " + tk.lineno());
        tk.pushBack();
      }
    } else if (tk.sval.equalsIgnoreCase("color")) {

      tk.nextToken();
      if (tk.ttype == '=') {
        tk.nextToken();
        if (tk.ttype == StreamTokenizer.TT_WORD || tk.ttype == '"') {
          ;
        } else {
          System.err.println("couldn't find color at line " + tk.lineno());
          tk.pushBack();
        }
      } else {
        System.err.println("couldn't find color at line " + tk.lineno());
        tk.pushBack();
      }
    }

    else if (tk.sval.equalsIgnoreCase("style")) {

      tk.nextToken();
      if (tk.ttype == '=') {
        tk.nextToken();
        if (tk.ttype == StreamTokenizer.TT_WORD || tk.ttype == '"') {
          ;
        } else {
          System.err.println("couldn't find style at line " + tk.lineno());
          tk.pushBack();
        }
      } else {
        System.err.println("couldn't find style at line " + tk.lineno());
        tk.pushBack();
      }
    }
  }
  edgeAttrib(tk, e);
}