net.sf.transjvm
Class Variable

java.lang.Object
  net.sf.transjvm.Expression
      net.sf.transjvm.Variable

public abstract class Variable
extends Expression

Variables represents storage locations in the JVM: locals, fields and array members. They can be read, so extend Expression, but can be written to as well, using the store and assign methods.

Author:

Mark Shannon

See Also:

FieldID.variable(Expression owner), FieldID.staticVariable(), Frame.variable(TypeID type), Frame.parameter(int index), Frame._this(), Expression.index(Expression index)

Field Summary

Fields inherited from class net.sf.transjvm.Expression

FALSE, NULL, ONE, TRUE, ZERO

Method Summary

Expression	assign(Expression value) Returns the assignment expression this = value.
abstract void	assign(Expression value, InstructionStream stream, int depth) Store value to this Variable and leave value on top of stack, returning stack height
Statement	increment(int incr) Returns a statement which increments this by incr.
Expression	postIncrement() Returns an expression which increments the variable by one as a side effect, and evaluates to the value of the variable after it has incremented.
Expression	preIncrement() Returns an expression which evaluates to the same as this Variable, while incrementing the variable by one as a side effect.
Statement	store(Expression value) Returns the assignment statement this = value.
abstract void	store(Expression value, InstructionStream stream) Store value to this Variable

Methods inherited from class net.sf.transjvm.Expression

accept, bitwise, bitwiseNot, branch, branch, branch, cast, compare, conditional, constant, constant, constant, constant, constant, convert, emptyArray, eval, filledArray, getType, index, isInstanceOf, length, logicalNot, math, negate, not, shortCut, toStm

Methods inherited from class java.lang.Object

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

Method Detail

store

public abstract void store(Expression value,
                           InstructionStream stream)

Store value to this Variable

assign

public abstract void assign(Expression value,
                            InstructionStream stream,
                            int depth)

Store value to this Variable and leave value on top of stack, returning stack height

preIncrement

public final Expression preIncrement()

Returns an expression which evaluates to the same as this Variable, while incrementing the variable by one as a side effect. This variable must have a numeric type.

postIncrement

public final Expression postIncrement()

Returns an expression which increments the variable by one as a side effect, and evaluates to the value of the variable after it has incremented. This variable must have a numeric type.

store

public Statement store(Expression value)

Returns the assignment statement this = value.

Parameters:

value - The value to be assigned.

Returns:

A statement which assigns value to this.

increment

public Statement increment(int incr)

Returns a statement which increments this by incr. Type must be INT32

Parameters:

incr - The amount to increment var by.

assign

public Expression assign(Expression value)

Returns the assignment expression this = value. Note that var.assign(value).toStm() is equivalent to var.store(value).

Parameters:

value - The value to be assigned.

Returns:

Expression which has the same value as value, but assigns value to this as a side effect.