com.google.gwt.dev.jjs.impl

Class CompoundAssignmentNormalizer

java.lang.Object

com.google.gwt.dev.jjs.impl.CompoundAssignmentNormalizer

Direct Known Subclasses:

PostOptimizationCompoundAssignmentNormalizer

public abstract class CompoundAssignmentNormalizer
extends Object

Replace problematic compound assignments with a sequence of simpler operations, all of which are either simple assignments or are non-assigning operations. When doing so, be careful that side effects happen exactly once and that the order of any side effects is preserved. The choice of which assignments to replace is made in subclasses; they must override the three shouldBreakUp() methods.

Note that because AST nodes are mutable, they cannot be reused in different parts of the same tree. Instead, the node must be cloned before each insertion into a tree other than the first.

Constructor Summary

Constructors

Constructor and Description
CompoundAssignmentNormalizer()

Method Summary

Modifier and Type	Method and Description
void	accept(JNode node)
protected JExpression	expressionToReturn(JExpression lhs) Decide what expression to return when breaking up a compound assignment of the form lhs op= rhs.
protected JExpression	modifyResultOperation(JBinaryOperation op) Decide what expression to return when breaking up a compound assignment of the form lhs op= rhs.
protected String	newTemporaryLocalName(SourceInfo info, JType type, JMethodBody methodBody) Gets a new temporary local variable name in methodBody.
protected abstract boolean	shouldBreakUp(JBinaryOperation x)
protected abstract boolean	shouldBreakUp(JPostfixOperation x)
protected abstract boolean	shouldBreakUp(JPrefixOperation x)

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, toString

Constructor Detail

CompoundAssignmentNormalizer

public CompoundAssignmentNormalizer()

Method Detail

accept

public void accept(JNode node)

newTemporaryLocalName

protected String newTemporaryLocalName(SourceInfo info,
                                       JType type,
                                       JMethodBody methodBody)

Gets a new temporary local variable name in methodBody. Locals might have duplicate names as they are always referred to by reference. GenerateJavaScriptAST will attempt coalesce variables of same name.

Subclasses might decide on different approaches to naming local temporaries.

expressionToReturn

protected JExpression expressionToReturn(JExpression lhs)

Decide what expression to return when breaking up a compound assignment of the form lhs op= rhs. By default the lhs is returned.

modifyResultOperation

protected JExpression modifyResultOperation(JBinaryOperation op)

Decide what expression to return when breaking up a compound assignment of the form lhs op= rhs. The breakup creates an expression of the form lhs = lhs op rhs, and the right hand side of the newly created expression is passed to this method.

shouldBreakUp

protected abstract boolean shouldBreakUp(JBinaryOperation x)

shouldBreakUp

protected abstract boolean shouldBreakUp(JPostfixOperation x)

shouldBreakUp

protected abstract boolean shouldBreakUp(JPrefixOperation x)