Parser.UdtCallback (Java APG)

java.lang.Object
- apg.Parser.UdtCallback

Direct Known Subclasses:

UdtLib.Alphanum, UdtLib.Any, UdtLib.CComment, UdtLib.Comment, UdtLib.DecNum, UdtLib.HexNum, UdtLib.LineEnd, UdtLib.QuotedString, UdtLib.WhiteSpace

Enclosing class:

Parser
```
public abstract static class Parser.UdtCallback
extends java.lang.Object
```
Base class for all User-Defined Terminals (UDTs).

- Field Summary
  
  Fields
  Modifier and Type Field Description
  
  Parser.CallbackData callbackData
  Parser-provisioned data available to all UDT callback functions
- Constructor Summary
  
  Constructors
  Constructor Description
  
  UdtCallback(Parser parser)
  Base class constructor for the UDT callback functions.
- Method Summary
  
  All Methods Instance Methods Abstract Methods
  Modifier and Type Method Description
  
  abstract int callback(int offset)
  The UDT function.
  - Methods inherited from class java.lang.Object
    equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - callbackData
```
public final Parser.CallbackData callbackData
```
    Parser-provisioned data available to all UDT callback functions
- Constructor Detail
  - UdtCallback
```
public UdtCallback(Parser parser)
```
    Base class constructor for the UDT callback functions.
    
    Parameters:
    
    parser - the instance of the Parser to attach this callback function to.
- Method Detail
  - callback
```
public abstract int callback(int offset)
                      throws java.lang.Exception
```
    The UDT function.
    
    Parameters:
    
    offset - offset into the input string to the first character of the parsed phrase.
    
    Returns:
    
    the matched phrase length, L, or -1 if no phrase was matched. The phrase length must be in the range 0 <= L <=(n-1), where n is the remaining number of characters in the input string.
    
    Throws:
    
    java.lang.Exception - thrown if the callback function returns an illegal value. An illegal value would be a phrase length L >= n, or Illegal values are phrase lengths longer than the length of the remaining input string or a zero (empty) length by a UDT designated as non-empty. (UDTs having names beginning with "u_" are designated as non-empty. UDTs having names beginning with "e_" are designated as empty.)