private Expression <Func <TType, IDiff, TType> > Compile()
{
ParameterExpression orig = Expression.Parameter(typeof(TType), "orig");
ParameterExpression diff = Expression.Parameter(typeof(IDiff), "diff");
ParameterExpression ret = Expression.Parameter(typeof(TType), "ret");
ParameterExpression item = Expression.Parameter(typeof(IDiffClassItem), "item");
return(Expression.Lambda <Func <TType, IDiff, TType> >(
Expression.Block(
new[] { ret },
Expression.Assign(
ret,
Expression.New(typeof(TType))
),
Expression.Block(Class <TType> .Properties.Select(property =>
Expression.Assign(
Expression.Property(ret, property.ReflectionPropertyInfo),
Expression.Property(orig, property.ReflectionPropertyInfo)
)
)),
ExpressionExtensions.ForEach(
item,
diff,
Expression.IfThen(
Expression.Not(Expression.TypeIs(item, typeof(IDiffItemUnchanged))),
Expression.Block(
Expression.Switch(
Expression.Property(
Expression.Property(
item,
DiffItemsMembers.ClassProperty()
),
FastPropertyMembers.UniqueID()
),
Expression.Throw(
Expression.New(typeof(Exception))
),
Class <TType> .Properties.Select(property => this.EvaluateProperty(ret, orig, property, item)).ToArray()
)
)
)
),
ret
),
orig, diff
));
}
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)
)
)
));
}