/** Class constructor. */
public SwitchStatement() {
if (!SectionInfo.in() && !FunctionInfo.in())
throw new NslContextException(EnumSet.of(NslContext.Section, NslContext.Function), "switch");
int lineNo = ScriptParser.tokenizer.lineno();
ScriptParser.tokenizer.matchOrDie('(');
this.switchExpression = Expression.matchComplex();
ScriptParser.tokenizer.matchOrDie(')');
ScriptParser.tokenizer.matchOrDie('{');
// Set non-null values so that the block statement can contain break statements.
CodeInfo.getCurrent().setBreakLabel(RelativeJump.Zero);
this.statementList = new ArrayList<Statement>();
this.casesList = new ArrayList<SwitchCaseStatement>();
this.defaultCase = null;
// Get the statements including case statements.
while (true) {
if (ScriptParser.tokenizer.match("case")) {
Statement statement = new SwitchCaseStatement();
if (this.defaultCase != null)
throw new NslException(
"The \"default\" case in a \"switch\" statement must be the last case", true);
this.casesList.add((SwitchCaseStatement) statement);
this.statementList.add(statement);
} else if (ScriptParser.tokenizer.match("default")) {
this.defaultCase = new SwitchDefaultCaseStatement();
this.statementList.add(this.defaultCase);
} else {
Statement statement = Statement.match();
if (statement == null) break;
this.statementList.add(statement);
}
}
// No cases?
if (this.casesList.isEmpty())
throw new NslException(
"A \"switch\" statement must have at least one \"case\" statement", true);
// Validate switch cases for jump instructions.
if (this.switchExpression instanceof JumpExpression)
((JumpExpression) this.switchExpression).checkSwitchCases(this.casesList, lineNo);
// Check the last statement is a break statement.
boolean noBreak = true;
if (!this.statementList.isEmpty()) {
Statement last = this.statementList.get(this.statementList.size() - 1);
if (last instanceof BlockStatement) last = ((BlockStatement) last).getLast();
if (last instanceof BreakStatement) noBreak = false;
}
if (noBreak)
throw new NslException("A \"switch\" statement must end with a \"break\" statement", true);
CodeInfo.getCurrent().setBreakLabel(null);
ScriptParser.tokenizer.matchOrDie('}');
}
/**
* Assembles the source code.
*
* @throws IOException
*/
@Override
public void assemble() throws IOException {
// Do not assemble anything if there are no cases!
if (this.casesList.isEmpty()) return;
// Give each case a label.
for (SwitchCaseStatement statement : this.casesList)
statement.setLabel(LabelList.getCurrent().getNext());
if (this.defaultCase != null) this.defaultCase.setLabel(LabelList.getCurrent().getNext());
Label gotoEnd = LabelList.getCurrent().getNext();
Label gotoStart = LabelList.getCurrent().getNext();
// Go to the jump table which is assembled after the switch case labels and
// statements.
ScriptParser.writeLine("Goto " + gotoStart);
// Using "break;" inside a switch jumps to the end.
Label parentBreak = CodeInfo.getCurrent().setBreakLabel(gotoEnd);
// Assemble all the statements inside the switch { }. This includes the
// case labels.
for (Statement statement : this.statementList) statement.assemble();
// Restore the parent break label.
CodeInfo.getCurrent().setBreakLabel(parentBreak);
// Label at the top of the jump table.
gotoStart.write();
// Jump instructions can jump directly to the case labels.
if (this.switchExpression instanceof JumpExpression) {
((JumpExpression) this.switchExpression).assemble(this.casesList);
}
// Other expressions we just assemble them if required and compare their
// result.
else {
Expression varOrSwitchExpression =
AssembleExpression.getRegisterOrExpression(this.switchExpression);
for (SwitchCaseStatement caseStatement : this.casesList) {
// Type is an integer; use IntCmp.
if (caseStatement.getMatch().getType().equals(ExpressionType.Integer)) {
ScriptParser.writeLine(
String.format(
"IntCmp %s %s %s",
varOrSwitchExpression, caseStatement.getMatch(), caseStatement.getLabel()));
}
// Type is a string; use StrCmp or StrCmpS (if special `` quotes were
// used).
else {
ScriptParser.writeLine(
String.format(
"StrCmp%s %s %s %s",
caseStatement.getMatch().getType().equals(ExpressionType.StringSpecial)
? "S"
: "",
varOrSwitchExpression,
caseStatement.getMatch(),
caseStatement.getLabel()));
}
}
varOrSwitchExpression.setInUse(false);
}
// Default case jump.
if (this.defaultCase != null) ScriptParser.writeLine("Goto " + this.defaultCase.getLabel());
gotoEnd.write();
}