com.saxonica.bytecode.util
Class OnEmpty

java.lang.Object
  com.saxonica.bytecode.util.OnEmpty

Direct Known Subclasses:

OnEmpty.ReturnEmptyString, OnEmpty.ReturnNull, OnEmpty.UnwindAndJump

public abstract class OnEmpty
extends Object

The OnEmpty class represents an action to be taken by the bytecode generator when compiling an expression to return a "primitive" (unboxed) value such as a double float int long or String (treated as primitive for this purpose). There are a number of defined subclasses and these are known to users of the class; it is not possible to introduce new subclasses without careful examination of existing code.

Nested Class Summary

static class	OnEmpty.ReturnEmptyString The ReturnNull subclass indicates that when an expression evaluates to the empty sequence, the value should be returned as a zero-length string.
static class	OnEmpty.ReturnNull The ReturnNull subclass indicates that when an expression evaluates to the empty sequence, the value should be returned as a Java null.
static class	OnEmpty.UnwindAndJump The UnwindAndJump subclass causes the code generator, when an expression evaluates to the empty sequence, to generate a "goto" instruction to a defined label; but before executing the jump, the stack will be unwound to a known position.

Field Summary

static OnEmpty	RETURN_EMPTY_STRING
static OnEmpty	RETURN_NULL

Constructor Summary

OnEmpty()

Method Summary

abstract void

generate(Generator ga)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

RETURN_EMPTY_STRING

public static final OnEmpty RETURN_EMPTY_STRING

RETURN_NULL

public static final OnEmpty RETURN_NULL

Constructor Detail

OnEmpty

public OnEmpty()

Method Detail

generate

public abstract void generate(Generator ga)