/**
* Returns an expression containing the side effects of the given expression. The evaluated result
* of the expression may differ from the original.
*/
private Expression extractSideEffects(Expression expr) {
switch (expr.getKind()) {
case INFIX_EXPRESSION:
{
List<Expression> operands = ((InfixExpression) expr).getOperands();
Expression lastOperand = operands.remove(operands.size() - 1);
lastOperand = extractSideEffects(lastOperand);
if (lastOperand != null) {
operands.add(lastOperand);
}
if (operands.size() == 1) {
return operands.remove(0);
}
return TreeUtil.remove(expr);
}
case PARENTHESIZED_EXPRESSION:
{
Expression sideEffects =
extractSideEffects(((ParenthesizedExpression) expr).getExpression());
if (sideEffects != null) {
return ParenthesizedExpression.parenthesize(sideEffects);
}
return null;
}
default:
return null;
}
}
/**
* Returns TRUE of FALSE if 'expr' is a boolean expression and its value is known statically. The
* caller should be careful when replacing this expression as it may have side effects.
*/
private Boolean getKnownValue(Expression expr) {
Object value = expr.getConstantValue();
if (value instanceof Boolean) {
return (Boolean) value;
}
switch (expr.getKind()) {
case BOOLEAN_LITERAL:
return ((BooleanLiteral) expr).booleanValue();
case INFIX_EXPRESSION:
{
InfixExpression infixExpr = (InfixExpression) expr;
InfixExpression.Operator op = infixExpr.getOperator();
if (op == CONDITIONAL_AND || op == CONDITIONAL_OR) {
// We assume that this node has already been visited and pruned so
// if it has a known value, it will be equal to the last operand.
List<Expression> operands = infixExpr.getOperands();
Boolean lastOperand = getKnownValue(operands.get(operands.size() - 1));
if (lastOperand != null && lastOperand.booleanValue() == (op == CONDITIONAL_OR)) {
return lastOperand;
}
}
return null;
}
case PARENTHESIZED_EXPRESSION:
return getKnownValue(((ParenthesizedExpression) expr).getExpression());
default:
return null;
}
}
private ITypeBinding getDeclaredType(Expression expr) {
IVariableBinding var = TreeUtil.getVariableBinding(expr);
if (var != null) {
return var.getVariableDeclaration().getType();
}
switch (expr.getKind()) {
case CLASS_INSTANCE_CREATION:
return typeEnv.resolveIOSType("id");
case FUNCTION_INVOCATION:
{
ITypeBinding returnType =
((FunctionInvocation) expr).getFunctionBinding().getReturnType();
if (returnType.isTypeVariable()) {
return typeEnv.resolveIOSType("id");
}
return returnType;
}
case METHOD_INVOCATION:
{
MethodInvocation invocation = (MethodInvocation) expr;
IMethodBinding method = invocation.getMethodBinding();
// Object receiving the message, or null if it's a method in this class.
Expression receiver = invocation.getExpression();
ITypeBinding receiverType =
receiver != null ? receiver.getTypeBinding() : method.getDeclaringClass();
return getDeclaredReturnType(method, receiverType);
}
case PARENTHESIZED_EXPRESSION:
return getDeclaredType(((ParenthesizedExpression) expr).getExpression());
case SUPER_METHOD_INVOCATION:
{
SuperMethodInvocation invocation = (SuperMethodInvocation) expr;
IMethodBinding method = invocation.getMethodBinding();
if (invocation.getQualifier() != null) {
// For a qualified super invocation, the statement generator will look
// up the IMP using instanceMethodForSelector.
if (!method.getReturnType().isPrimitive()) {
return typeEnv.resolveIOSType("id");
} else {
return null;
}
}
return getDeclaredReturnType(
method, TreeUtil.getOwningType(invocation).getTypeBinding().getSuperclass());
}
default:
return null;
}
}
