protected override Expression VisitIndex(IndexExpression node)
{
int yields = _yields.Count;
Expression o = Visit(node.Object);
ReadOnlyCollection <Expression> a = Visit(node.Arguments);
if (o == node.Object && a == node.Arguments)
{
return(node);
}
if (yields == _yields.Count)
{
return(Expression.MakeIndex(o, node.Indexer, a));
}
return(Expression.Block(
ToTemp(ref o),
ToTemp(ref a),
Expression.MakeIndex(o, node.Indexer, a)
));
}
private Expression VisitAssign(BinaryExpression node)
{
int yields = _yields.Count;
Expression left = Visit(node.Left);
Expression right = Visit(node.Right);
if (left == node.Left && right == node.Right)
{
return(node);
}
if (yields == _yields.Count)
{
return(Expression.Assign(left, right));
}
var block = new List <Expression>();
// If the left hand side did not rewrite itself, we may still need
// to rewrite to ensure proper evaluation order. Essentially, we
// want all of the left side evaluated first, then the value, then
// the assignment
if (left == node.Left)
{
switch (left.NodeType)
{
case ExpressionType.MemberAccess:
var member = (MemberExpression)node.Left;
Expression e = Visit(member.Expression);
block.Add(ToTemp(ref e));
left = Expression.MakeMemberAccess(e, member.Member);
break;
case ExpressionType.Index:
var index = (IndexExpression)node.Left;
Expression o = Visit(index.Object);
ReadOnlyCollection <Expression> a = Visit(index.Arguments);
if (o == index.Object && a == index.Arguments)
{
return(index);
}
block.Add(ToTemp(ref o));
block.Add(ToTemp(ref a));
left = Expression.MakeIndex(o, index.Indexer, a);
break;
case ExpressionType.Parameter:
// no action needed
break;
default:
// Extension should've been reduced by Visit above,
// and returned a different node
throw Assert.Unreachable;
}
}
else
{
// Get the last expression of the rewritten left side
var leftBlock = (BlockExpression)left;
left = leftBlock.Expressions[leftBlock.Expressions.Count - 1];
block.AddRange(leftBlock.Expressions);
block.RemoveAt(block.Count - 1);
}
if (right != node.Right)
{
block.Add(ToTemp(ref right));
}
block.Add(Expression.Assign(left, right));
return(Expression.Block(block));
}
