private Expression EvaluateProperty(ParameterExpression leftEnumerator, ParameterExpression leftSomeLeft, ParameterExpression rightEnumerator, ParameterExpression rightSomeLeft, Expression conflicts, Expression ret, Property property)
{
Expression leftCurrent = Expression.Property(leftEnumerator, EnumerableMembers.Current(typeof(IDiffItem)));
Expression rightCurrent = Expression.Property(rightEnumerator, EnumerableMembers.Current(typeof(IDiffItem)));
/* PSEUDO CODE FOR THIS:
* if (leftSomeLeft && leftCurrent.UniqueID == ID)
* {
* if (rightSomeLeft && rightCurrent.UniqueID == ID)
* {
* CheckConflicts(leftCurrent, rightCurrent)
* rightSomeLeft = next(rightCurrent)
* }
* else
* add(leftCurrent)
* leftSomeLeft = next(leftCurrent)
* }
* else if (rightSomeLeft && rightCurrent.UniqueID == ID)
* {
* add(rightCurrent)
* rightSomeLeft = next(rightCurrent)
* }
*/
Expression leftShouldBeProcessed = Expression.AndAlso(
leftSomeLeft,
Expression.Equal(
Expression.Property(
Expression.Property(
Expression.Convert(
leftCurrent,
typeof(IDiffClassItem)
),
DiffItemsMembers.ClassProperty()
),
FastPropertyMembers.UniqueID()
),
Expression.Constant(property.UniqueID)
)
);
Expression rightShouldBeProcessed = Expression.AndAlso(
rightSomeLeft,
Expression.Equal(
Expression.Property(
Expression.Property(
Expression.Convert(
rightCurrent,
typeof(IDiffClassItem)
),
DiffItemsMembers.ClassProperty()
),
FastPropertyMembers.UniqueID()
),
Expression.Constant(property.UniqueID)
)
);
return(Expression.IfThenElse(
leftShouldBeProcessed,
Expression.Block(
Expression.IfThenElse(
rightShouldBeProcessed,
Expression.Block(
this.CompileCheckConflicts(property, leftCurrent, rightCurrent, conflicts, ret),
this.MoveEnumerator(rightEnumerator, rightSomeLeft)
),
Expression.Call(
ret,
ListMembers.Add(typeof(IDiffItem)),
leftCurrent
)
),
this.MoveEnumerator(leftEnumerator, leftSomeLeft)
),
Expression.IfThen(
rightShouldBeProcessed,
Expression.Block(
Expression.Call(
ret,
ListMembers.Add(typeof(IDiffItem)),
rightCurrent
),
this.MoveEnumerator(rightEnumerator, rightSomeLeft)
)
)
));
}
public static Expression ForEach(ParameterExpression item, Expression source, Expression body)
{
if (!typeof(IEnumerable).IsAssignableFrom(source.Type))
{
throw new InvalidOperationException($"{source.Type} does not implement IEnumerable and cannot be iterated using foreach");
}
ParameterExpression enumerator = Expression.Parameter(typeof(IEnumerator), "enumerator");
LabelTarget forEachEnd = Expression.Label();
return(Expression.Block(
new[] { item, enumerator },
Expression.Assign(
enumerator,
Expression.Call(source, EnumerableMembers.GetEnumerator())
),
Expression.Loop(
Expression.IfThenElse(
Expression.Call(enumerator, EnumerableMembers.MoveNext()),
Expression.Block(
Expression.Assign(item, Expression.Convert(Expression.Property(enumerator, EnumerableMembers.Current()), item.Type)),
body
),
Expression.Break(forEachEnd)
),
forEachEnd
)
));
}