Field Detail

• originalModeString

  public final java.lang.String originalModeString

  Original string supplied as the mode

• reading

  public boolean reading

  Whether this file is opened for reading ('r')

• writing

  public boolean writing

  Whether this file is opened for writing ('w')

• appending

  public boolean appending

  Whether this file is opened in appending mode ('a')

• updating

  public boolean updating

  Whether this file is opened for updating ('+')

• binary

  public boolean binary

  Whether this file is opened in binary mode ('b')

• text

  public boolean text

  Whether this file is opened in text mode ('t')

• universal

  public boolean universal

  Whether this file is opened in universal newlines mode ('U')

• other

  public boolean other

  Whether the mode contained some other symbol from the allowed ones

• invalid

  public boolean invalid

  Set true when any invalid symbol or combination is discovered

• message

  public java.lang.String message

  Error message describing the way in which the mode is invalid, or null if no problem has been found. This field may be set by the constructor (in the case of duplicate or unrecognised mode letters), by the validate() method, or by client code.

Constructor Detail

• OpenMode

  public OpenMode​(java.lang.String mode)

  Decode the given string to an OpenMode object, checking for duplicate or unrecognised mode letters. Valid letters are those in "rwa+btU". Errors in the mode string do not raise an exception, they simply generate an appropriate error message in message. After construction, a client should always call validate() to complete validity checks.

  Parameters:

  mode -

Method Detail

• validate

  public void validate()

  Adjust and validate the flags decoded from the mode string. The method affects the flags where the presence of one flag implies another, then if the invalid flag is not already true, it checks the validity of the flags against combinations allowed by the Python io.open() function. In the case of a violation, it sets the invalid flag, and sets message to a descriptive message. The point of the qualification "if the invalid flag is not already true" is that the message should always describe the first problem discovered. If left blank, as in fact the constructor does, it will be filled by the generic message when checkValid() is finally called. Clients may override this method (by sub-classing) to express the validation correct in their context.

  The invalid combinations enforced here are those for the "raw" (ie non-text) file types:

  • universal & (writing | appending),
  • text & binary,
  • reading & writing,
  • appending & (reading | writing)

  See also validate(String, String, String) for additional checks relevant to text files.

• validate

  public void validate​(java.lang.String encoding,
                       java.lang.String errors,
                       java.lang.String newline)

  Perform additional validation of the flags relevant to text files. If invalid is not already true, and the mode includes binary, then all the arguments to this call must be null. If the criterion is not met, then on return from the method, invalid==true and message is set to a standard error message. This is the standard additional validation applicable to text files. (By "standard" we mean the test and messages that CPython io.open uses.)

  Parameters:

  encoding - argument to open()

  errors - argument to open()

  newline - argument to open()

• checkValid

  public void checkValid()
                  throws PyException

  Call validate() and raise an exception if the mode string is not valid, as signalled by either invalid or other being true after that call. If no more specific message has been assigned in message, report the original mode string.

  Throws:

  PyException - ValueError if the mode string was invalid.

• forFileIO

  public java.lang.String forFileIO()

  The mode string we need when constructing a FileIO initialised with the present mode. Note that this is not the same as the full open mode because it omits the text-based attributes.

  Returns:

  "r", "w", or "a" with optional "+".

• text

  public java.lang.String text()

  The mode string that a text file should claim to have, when initialised with the present mode. Note that this only contains text-based attributes. Since mode 't' has no effect, except to produce an error if specified with 'b', we don't reproduce it.

  Returns:

  "", or "U".

• toString

  public java.lang.String toString()

  Overrides:

  toString in class java.lang.Object