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 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
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// This file contains the declaration of class TextReader.

#ifndef O3D_UTILS_CROSS_TEXT_READER_H_
#define O3D_UTILS_CROSS_TEXT_READER_H_

#include <string>
#include "base/basictypes.h"

namespace o3d {

// TextReader is the abstract base class of classes
// that read a sequence of characters to an underlying
// medium.
class TextReader {
 public:
  // Construct a new TextReader.
  TextReader();
  virtual ~TextReader();

  // Returns true if at the end of the input.
  virtual bool IsAtEnd() const = 0;

  // Read ahead up to count characters and return them as a string,
  // but don't modify the input's current position.  Returns the empty
  // string if at the end of the input.
  virtual std::string PeekString(std::string::size_type count) const = 0;

  // Read a single character.
  virtual char ReadChar() = 0;

  // Read a number of characters as a string.  If the input isn't that
  // long, the string may be shorter than the given number of
  // characters.  Returns an empty string if it is already at the end
  // of the input or if there is an error.
  virtual std::string ReadString(std::string::size_type count) = 0;

  // Read a line of text, terminated by any kind of line terminator
  // (LF/CRLF/CR).  Returns the empty string if at end of input, or if
  // there is an error.
  virtual std::string ReadLine() = 0;

  // Read the remaining file into a string, linefeeds and all.
  // Returns the empty string if already at the end of the file or
  // there is an error.
  virtual std::string ReadToEnd() = 0;

 protected:
  // Returns length of EOL marker (one or two characters) if the given
  // character string starts with an end of line marker.  Returns zero
  // if there is no EOL marker at the BEGINNING of the string.
  static int TestForEndOfLine(const std::string& eol);

 private:

  DISALLOW_COPY_AND_ASSIGN(TextReader);
};
}  // namespace o3d

#endif  // O3D_UTILS_CROSS_TEXT_READER_H_