private static boolean hasDefaultClause(SwitchStatement node) {
for (SwitchClause switchClause : node.getClauses()) {
if (switchClause.isDefaultClause()) {
return true;
}
}
return false;
}
private static boolean isStringSwitch(SwitchStatement node) {
for (SwitchClause switchClause : node.getClauses()) {
Expression expr = switchClause.getExpression();
if (expr != null && !(expr instanceof StringLiteral)) {
return false;
}
}
return true;
}
private static boolean isCharSwitch(SwitchStatement node) {
for (SwitchClause switchClause : node.getClauses()) {
Expression expr = switchClause.getExpression();
if (expr != null) {
if (expr instanceof StringLiteral && ((StringLiteral) expr).getValue().length() == 1) {
continue;
}
return false;
}
}
return true;
}
static SwitchType of(SwitchStatement node) {
List<SwitchClause> clauses = node.getClauses();
if (clauses.size() == 0 || clauses.size() == 1 && clauses.get(0).isDefaultClause()) {
// empty or only default clause
return Default;
}
if (isIntSwitch(node)) {
return Int;
}
if (isCharSwitch(node)) {
return Char;
}
if (isStringSwitch(node)) {
return String;
}
return Generic;
}
private static boolean isIntSwitch(SwitchStatement node) {
for (SwitchClause switchClause : node.getClauses()) {
Expression expr = switchClause.getExpression();
if (expr != null) {
if (expr instanceof NumericLiteral && ((NumericLiteral) expr).isInt()) {
continue;
}
if (expr instanceof UnaryExpression
&& ((UnaryExpression) expr).getOperator() == UnaryExpression.Operator.NEG
&& ((UnaryExpression) expr).getOperand() instanceof NumericLiteral
&& ((NumericLiteral) ((UnaryExpression) expr).getOperand()).isInt()
&& ((NumericLiteral) ((UnaryExpression) expr).getOperand()).intValue() != 0) {
continue;
}
return false;
}
}
return true;
}
/**
* 13.12.9 Runtime Semantics: CaseBlockEvaluation
*
* @param node the switch statement
* @param type the switch statement type
* @param lblExit the exit label
* @param switchValue the variable which holds the switch value
* @param mv the statement visitor
* @return the completion value
*/
private Completion CaseBlockEvaluation(
SwitchStatement node,
SwitchType type,
Jump lblExit,
Variable<?> switchValue,
StatementVisitor mv) {
List<SwitchClause> clauses = node.getClauses();
Jump lblDefault = null;
Jump[] labels = new Jump[clauses.size()];
for (int i = 0, size = clauses.size(); i < size; ++i) {
labels[i] = new Jump();
if (clauses.get(i).isDefaultClause()) {
assert lblDefault == null;
lblDefault = labels[i];
}
}
if (type == SwitchType.Int) {
emitIntSwitch(clauses, labels, lblDefault, lblExit, switchValue, mv);
} else if (type == SwitchType.Char) {
emitCharSwitch(clauses, labels, lblDefault, lblExit, switchValue, mv);
} else if (type == SwitchType.String) {
emitStringSwitch(clauses, labels, lblDefault, lblExit, switchValue, mv);
} else if (type == SwitchType.Generic) {
emitGenericSwitch(clauses, labels, lblDefault, lblExit, switchValue, mv);
} else {
assert type == SwitchType.Default;
assert switchValue == null;
// Directly jump to default clause; since switch clauses before default clause are not
// emitted, jump instruction can be elided as well, so we directly fall into the default
// clause.
}
Completion result = Completion.Normal, lastResult = Completion.Normal;
if (type == SwitchType.Default) {
Iterator<SwitchClause> iter = clauses.iterator();
// skip leading clauses until default clause found
while (iter.hasNext()) {
SwitchClause switchClause = iter.next();
if (switchClause.isDefaultClause()) {
lastResult = switchClause.accept(this, mv);
break;
}
}
// handle clauses following default clause until abrupt completion
while (iter.hasNext() && !lastResult.isAbrupt()) {
lastResult = iter.next().accept(this, mv);
}
result = lastResult;
} else {
int index = 0;
for (SwitchClause switchClause : clauses) {
Jump caseLabel = labels[index++];
if (caseLabel != null) {
mv.mark(caseLabel);
} else if (lastResult.isAbrupt()) {
// Ignore unreachable targets
continue;
}
Completion innerResult = switchClause.accept(this, mv);
if (innerResult.isAbrupt()) {
// not fall-thru
result = result.isAbrupt() ? result.select(innerResult) : innerResult;
}
lastResult = innerResult;
}
}
return result.normal(lblDefault == null || !lastResult.isAbrupt());
}
/** 13.12.11 Runtime Semantics: Evaluation */
@Override
public Completion visit(SwitchStatement node, StatementVisitor mv) {
// stack -> switchValue
ValType switchValueType = expression(node.getExpression(), mv);
SwitchType type = SwitchType.of(node);
boolean defaultOrReturn = false;
if (type == SwitchType.Int) {
if (!switchValueType.isNumeric() && switchValueType != ValType.Any) {
defaultOrReturn = true;
}
} else if (type == SwitchType.Char) {
if (switchValueType != ValType.String && switchValueType != ValType.Any) {
defaultOrReturn = true;
}
} else if (type == SwitchType.String) {
if (switchValueType != ValType.String && switchValueType != ValType.Any) {
defaultOrReturn = true;
}
} else if (type == SwitchType.Generic) {
mv.toBoxed(switchValueType);
switchValueType = ValType.Any;
} else {
assert type == SwitchType.Default;
defaultOrReturn = true;
}
final boolean defaultClausePresent = hasDefaultClause(node);
if (defaultOrReturn) {
// never true -> emit default switch or return
mv.pop(switchValueType);
if (defaultClausePresent) {
type = SwitchType.Default;
} else {
return Completion.Normal;
}
}
mv.enterVariableScope();
Variable<LexicalEnvironment<?>> savedEnv = saveEnvironment(node, mv);
Variable<?> switchValue = null;
if (type != SwitchType.Default) {
switchValue = mv.newVariable("switchValue", switchValueType.toClass());
mv.store(switchValue);
}
BlockScope scope = node.getScope();
if (scope.isPresent()) {
newDeclarativeEnvironment(scope, mv);
codegen.blockInit(node, mv);
pushLexicalEnvironment(mv);
}
Jump lblExit = new Jump();
BreakLabel lblBreak = new BreakLabel();
mv.enterScope(node);
mv.enterBreakable(node, lblBreak);
Completion result = CaseBlockEvaluation(node, type, lblExit, switchValue, mv);
mv.exitBreakable(node);
mv.exitScope();
if (!defaultClausePresent) {
mv.mark(lblExit);
}
if (scope.isPresent() && !result.isAbrupt()) {
popLexicalEnvironment(mv);
}
if (lblBreak.isTarget()) {
mv.mark(lblBreak);
restoreEnvironment(savedEnv, mv);
}
mv.exitVariableScope();
return result.normal(lblBreak.isTarget());
}