protected override IEnumerable <BaseStatement> Visit(CompoundAssignment compAss)
{
var tmp = new VariableName(_names.Name());
var a = new ExpressionDecomposition(_names).Visit(compAss.Expression).ToArray();
var b = new Assignment(tmp, BaseBinaryExpression.Create(compAss.Op, new Variable(new VariableName(compAss.Left.Name)), new Variable(((Assignment)a.Last()).Left)));
var c = new Assignment(new VariableName(compAss.Left.Name), new Variable(tmp));
return(a.Append(b).Append(c));
}
public string Name()
{
while (true)
{
var n = _inner.Name();
if (!_taken.Contains(n))
{
return(n);
}
}
}
protected override BaseStatement Visit(If @if)
{
// Check that each branch contains just one statement...
if (@if.FalseBranch.Statements.Count != 1)
{
return(@if);
}
if (@if.TrueBranch.Statements.Count != 1)
{
return(@if);
}
// ...and that those statements are goto statements
if (!(@if.TrueBranch.Statements.Single() is Goto gotoTrue))
{
return(@if);
}
if (!(@if.FalseBranch.Statements.Single() is Goto gotoFalse))
{
return(@if);
}
// if A then goto B else goto C end
var a = new Bracketed(new Or(@if.Condition, new ConstantNumber(0)));
var b = new Bracketed(gotoTrue.Destination);
var c = new Bracketed(gotoFalse.Destination);
// goto A*(B-C)+C
var g1 = new Goto(new Add(c, new Multiply(a, new Bracketed(new Subtract(b, c)))));
// x=C goto A*(B-x)+x
var x = new VariableName(_names.Name());
var g2 = new StatementList(
new Assignment(x, c),
new Goto(new Add(new Multiply(a, new Bracketed(new Subtract(b, new Variable(x)))), new Variable(x)))
);
// Return the shortest one (ignoring the length of the temporary variable name, assume that's optimised to 1 char)
var xl = x.Name.Length * 2;
if (g1.ToString().Length <= g2.ToString().Length - xl + 2)
{
return(g1);
}
else
{
return(g2);
}
}
private VariableName MkTmp() => new VariableName(_names.Name());