net.sf.jode.expr
Class Expression

java.lang.Object
  net.sf.jode.expr.Expression

Direct Known Subclasses:

NopOperator, Operator

public abstract class Expression
extends Object

Field Summary

static Expression	EMPTYSTRING
protected Type	type

Constructor Summary

Expression(Type type)

Method Summary

abstract Expression	addOperand(Expression op)
int	canCombine(CombineableOperator combOp) Checks if the given Expression (which should be a CombineableOperator) can be combined into this expression.
Expression	combine(CombineableOperator comb) Combines the given Expression (which should be a StoreInstruction) into this expression.
boolean	containsConflictingLoad(MatchableOperator op) Checks if this expression contains a conflicting load, that matches the given CombineableOperator.
boolean	containsMatchingLoad(CombineableOperator e) Checks if this expression contains a load, that matches the given CombineableOperator (which must be an Operator)
void	dumpExpression(int options, TabbedPrintWriter writer)
abstract void	dumpExpression(TabbedPrintWriter writer)
void	dumpExpression(TabbedPrintWriter writer, int minPriority)
void	fillDeclarables(Collection used)
void	fillInGenSet(Collection in, Collection gen)
int	getBreakPenalty() Get the penalty for splitting up this operator.
abstract int	getFreeOperandCount() Get the number of operands.
Operator	getParent()
abstract int	getPriority() Get priority of the operator.
Type	getType()
boolean	hasSideEffects(Expression expr) Checks if the value of the given expression can change, due to side effects in this expression.
boolean	isConstant()
boolean	isVoid()
void	makeDeclaration(Set done)
void	makeInitializer(Type type)
Expression	negate()
Expression	removeOnetimeLocals() This method should remove local variables that are only written and read one time directly after another.
void	setType(Type otherType)
Expression	simplify()
Expression	simplifyString()
Expression	simplifyStringBuffer()
String	toString()
void	updateParentType(Type otherType)
abstract void	updateSubTypes() Tells an expression that an outer expression has changed our type and that the inner types should be recalculated.
abstract void	updateType() Tells an expression that an inner expression may have changed and that the type should be recalculated.

Methods inherited from class java.lang.Object

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

Field Detail

type

protected Type type

EMPTYSTRING

public static Expression EMPTYSTRING

Constructor Detail

Expression

public Expression(Type type)

Method Detail

setType

public void setType(Type otherType)

updateParentType

public void updateParentType(Type otherType)

updateType

public abstract void updateType()

Tells an expression that an inner expression may have changed and that the type should be recalculated. This may call setType of the caller again.

updateSubTypes

public abstract void updateSubTypes()

Tells an expression that an outer expression has changed our type and that the inner types should be recalculated.

getType

public Type getType()

getParent

public Operator getParent()

getPriority

public abstract int getPriority()

Get priority of the operator. Currently this priorities are known:

• 1000 constant
• 950 new, .(field access), []
• 900 new[]
• 800 ++,-- (post)
• 700 ++,--(pre), +,-(unary), ~, !, cast
• 650 *,/, %
• 610 +,-
• 600 <<, >>, >>>
• 550 >, <, >=, <=, instanceof
• 500 ==, !=
• 450 &
• 420 ^
• 410 |
• 350 &&
• 310 ||
• 200 ?:
• 100 =, +=, -=, etc.

getBreakPenalty

public int getBreakPenalty()

Get the penalty for splitting up this operator.

getFreeOperandCount

public abstract int getFreeOperandCount()

Get the number of operands.

Returns:

The number of stack entries this expression needs.

addOperand

public abstract Expression addOperand(Expression op)

negate

public Expression negate()

hasSideEffects

public boolean hasSideEffects(Expression expr)

Checks if the value of the given expression can change, due to side effects in this expression. If this returns false, the expression can safely be moved behind the current expresion.

Parameters:

expr - the expression that should not change.

canCombine

public int canCombine(CombineableOperator combOp)

Checks if the given Expression (which should be a CombineableOperator) can be combined into this expression.

Parameters:

combOp - The store expression, must be of type void.

Returns:

1, if it can, 0, if no match was found and -1, if a conflict was found. You may wish to check for >0.

containsMatchingLoad

public boolean containsMatchingLoad(CombineableOperator e)

Checks if this expression contains a load, that matches the given CombineableOperator (which must be an Operator)

Parameters:

e - The store expression.

Returns:

if this expression contains a matching load.

Throws:

ClassCastException, - if e.getOperator is not a CombineableOperator.

containsConflictingLoad

public boolean containsConflictingLoad(MatchableOperator op)

Checks if this expression contains a conflicting load, that matches the given CombineableOperator. The sub expressions are not checked.

Parameters:

op - The combineable operator.

Returns:

if this expression contains a matching load.

combine

public Expression combine(CombineableOperator comb)

Combines the given Expression (which should be a StoreInstruction) into this expression. You must only call this if canCombine returns the value 1.

Parameters:

comb - The store expression, the operator must be a CombineableOperator.

Returns:

The combined expression.

Throws:

ClassCastException, - if e.getOperator is not a CombineableOperator.

removeOnetimeLocals

public Expression removeOnetimeLocals()

This method should remove local variables that are only written and read one time directly after another.
In this case this is a non void LocalStoreOperator, whose local isn't used in other places.

Returns:

an expression where the locals are removed.

simplify

public Expression simplify()

simplifyString

public Expression simplifyString()

simplifyStringBuffer

public Expression simplifyStringBuffer()

makeInitializer

public void makeInitializer(Type type)

isConstant

public boolean isConstant()

fillInGenSet

public void fillInGenSet(Collection in,
                         Collection gen)

fillDeclarables

public void fillDeclarables(Collection used)

makeDeclaration

public void makeDeclaration(Set done)

dumpExpression

public abstract void dumpExpression(TabbedPrintWriter writer)
                             throws IOException

Throws:

IOException

dumpExpression

public void dumpExpression(int options,
                           TabbedPrintWriter writer)
                    throws IOException

Throws:

IOException

dumpExpression

public void dumpExpression(TabbedPrintWriter writer,
                           int minPriority)
                    throws IOException

Throws:

IOException

toString

public String toString()

Overrides:

toString in class Object

isVoid

public boolean isVoid()