void SimplifyActionBlocks()
{
int index = 0;
while (index < _blocks.Count)
{
ActionBlock block = _blocks [index];
switch (block.ActionType)
{
case ActionType.ConditionalBranch:
// if condition goto label
// return expression
// label: return true
// |
// V
// return (condition || expression)
//
// label: return false
// |
// V
// return (!condition || expression)
ConditionalBranchActionBlock cbr = (ConditionalBranchActionBlock)block;
if (IsReturnTrueOrFalse(cbr.Then) &&
IsReturn(cbr.Else) &&
1 == cbr.Then.Predecessors.Count &&
1 == cbr.Else.Predecessors.Count)
{
BinaryOperator op = BinaryOperator.LogicalOr;
Expression lhs = cbr.Condition;
Expression rhs = ((ReturnActionBlock)cbr.Else).Expression;
if (((LiteralExpression)((ReturnActionBlock)cbr.Then).Expression).Value.Equals(0))
{
op = BinaryOperator.LogicalAnd;
_expressionDecompiler.Negate(lhs);
lhs = _expressionDecompiler.Pop();
}
ActionBlock newBlock = new ReturnActionBlock(
block.SourceInstruction,
new BinaryExpression(op, lhs, rhs));
_graph.ReplaceAt(index, newBlock);
index = 0;
continue;
}
break;
}
++index;
}
}
private ActionBlock OnReturn(ReturnActionBlock block)
{
Expression expression = block.Expression;
VariableReferenceExpression variable = expression as VariableReferenceExpression;
_queryExpression =
variable != null
? _variables[GetVariableIndex(variable)]
: expression;
return null;
}
void WriteReturn (ReturnActionBlock block)
{
_writer.Write ("return");
if (null != block.Expression) {
_writer.Write (" ");
WriteExpression (block.Expression);
}
}
static bool IsReturnTrueOrFalse(ActionBlock block)
{
ReturnActionBlock ret = block as ReturnActionBlock;
return(ret != null && IsTrueOrFalse(ret.Expression));
}
void SimplifyActionBlocks ()
{
int index = 0;
while (index < _blocks.Count) {
ActionBlock block = _blocks [index];
switch (block.ActionType) {
case ActionType.ConditionalBranch:
/// if condition goto label
/// return expression
/// label: return true
/// |
/// V
/// return (condition || expression)
///
/// label: return false
/// |
/// V
/// return (!condition || expression)
ConditionalBranchActionBlock cbr = (ConditionalBranchActionBlock)block;
if (IsReturnTrueOrFalse (cbr.Then)
&& IsReturn (cbr.Else)
&& 1 == cbr.Then.Predecessors.Count
&& 1 == cbr.Else.Predecessors.Count) {
BinaryOperator op = BinaryOperator.LogicalOr;
Expression lhs = cbr.Condition;
Expression rhs = ((ReturnActionBlock) cbr.Else).Expression;
if (((LiteralExpression) ((ReturnActionBlock) cbr.Then).Expression).Value.Equals (0)) {
op = BinaryOperator.LogicalAnd;
_expressionDecompiler.Negate (lhs);
lhs = _expressionDecompiler.Pop ();
}
ActionBlock newBlock = new ReturnActionBlock (
block.SourceInstruction,
new BinaryExpression (op, lhs, rhs));
_graph.ReplaceAt (index, newBlock);
index = 0;
continue;
}
break;
}
++index;
}
}
