• • Description
  • Operations
    • 1 Equals
  • Description
  • Operations
    • 2 Constructor
    • 3 Equals
    • 4 Destructor
    • 5 GetBytes
  • Description
    • 6 Thread safety

5 External Classes

The present document relies on various occasions on which are not GATObjects. The realisation and implementation of these types is in general language dependent, and in many cases can be reduced to native classes. This appendix describes the minimal functionality the GAT expects from these types. When in some language an equivalent of such classes does not exist, GAT has to implement it.

For some of the listed classes, like Buffer, a functionally extended equivalent MAY be added as GATClass (e.g.  GATBuffer) in a later version of the specification.

List

Description

An of this is a list of instances. Some languages have ``native'' List types which MAY be used. If no such native List type exists, then a GAT implementation must include a List type.

Operations

1 Equals

Tests this List for equality with the passed instance.

If the passed is not a List instance, then this operation immediately returns False.

If the passed is a List instance, then it is deemed equal to this if it consists of the ``same'' elements, as determined by the Equals operation on the respective elements, in the same order as this List instance.

Inputs:

Object -- object -- Object to test for equality.

Outputs:

Bool -- equal -- Boolean indicating equality.

String

Description

An of the String represents a character string. The String provides various for manipulation of String instances.

Operations

2 Constructor

Constructs a new String by decoding the specified List of bytes using the specified charset. The length of the new String is a function of the charset, and hence MAY not be equal to the length of the byte List. The behaviour of this constructor when the given bytes are not valid in the given charset is unspecified.

The currently supported charsets are as follows

• US-ASCII -- Seven-bit ASCII, a.k.a. ISO646-US, a.k.a. the Basic Latin block of the Unicode character set
• ISO-8859-1 -- ISO Latin Alphabet No. 1, a.k.a. ISO-LATIN-1
• UTF-8 -- Eight-bit UCS Transformation Format
• UTF-16BE -- Sixteen-bit UCS Transformation Format, big-endian byte order
• UTF-16LE -- Sixteen-bit UCS Transformation Format, little-endian byte order
• UTF-16 -- Sixteen-bit UCS Transformation Format, byte order identified by an optional byte-order mark
  

Inputs:

Buffer -- buffer -- The bytes to be decoded into characters.

String -- charset -- Name of a supported charset.

3 Equals

Compares this string to the specified object. The result is True if and only if the argument is not null and is a String object that represents the same sequence of characters as this object

Inputs:

Object -- object -- Object to test for equality.

Outputs:

Bool -- equal -- Boolean indicating equality.

4 Destructor

Destroys this String object.

5 GetBytes

Encodes this String into a sequence of bytes using the named charset, storing the result into a new byte List. The behaviour of this when this string cannot be encoded in the given charset is unspecified.

Inputs:

String -- charset -- Charset to use for conversion.

Outputs:

Buffer -- buffer -- Resultant bytes.

Buffer

Description

A buffer is a container for arbitrary data. In most languages, this can be represented as an array of bytes. The application is responsible for reading and writing such buffers, and in particular for correct (de)serialisation of primitive and complex types during that process.

The GAT API specification MAY in a later version be extended with a GATBuffer class providing more sophisticated handling of typed data.

6 Thread safety

Buffers need not to be safe for use by multiple concurrent threads. If a buffer is to be used by more than one thread then access to the buffer SHOULD be controlled by appropriate synchronisation.