public Func <TTarget, TSource, TTarget> GetMapperFunc()
{
ValidateMapping();
var targetParam = Expression.Parameter(typeof(TTarget));
var sourceParam = Expression.Parameter(typeof(TSource));
var setterActions = TargetValues.OrderBy(x => x.PropertyName)
.Zip(SourceValues.OrderBy(x => x.PropertyName), (tgt, src) => tgt.CreateSetter(src.CreateGetter()))
.Concat(CustomMappings)
.Select(x => EnsureReturnsTarget(x))
.ToArray()
;
if (!setterActions.Any())
{
return((tgt, src) => tgt);
}
var accumulatedLambda = Expression.Invoke(setterActions.First(), targetParam, sourceParam);
foreach (var setterExpr in setterActions.Skip(1))
{
accumulatedLambda = Expression.Invoke(setterExpr, accumulatedLambda, sourceParam);
}
var mapperFunc = Expression.Lambda <Func <TTarget, TSource, TTarget> >(accumulatedLambda, targetParam, sourceParam);
return(mapperFunc.Compile());
}
private void ValidateMapping()
{
var targetNames = TargetValues.Select(x => x.PropertyName);
var sourceNames = SourceValues.Select(x => x.PropertyName);
var unmatchedTargets = targetNames.Except(sourceNames);
foreach (var targetProperty in GetUnmappedTargetValues())
{
ThrowUnmatchedTarget(targetProperty);
}
var unmatchedSources = sourceNames.Except(targetNames);
foreach (var sourceProperty in unmatchedSources)
{
ThrowUnmatchedSource(SourceValues.First(x => x.PropertyName == sourceProperty));
}
var mismatchedTypes = SourceValues.OrderBy(x => x.PropertyName)
.Zip(TargetValues.OrderBy(x => x.PropertyName), (src, tgt) => new
{
src,
tgt
})
.Where(x => !x.tgt.ValueType.IsAssignableFrom(x.src.ValueType));
foreach (var mismatch in mismatchedTypes)
{
var msg = string.Format(
"Cannot map [{0}] from [{1}].",
mismatch.tgt.Description,
mismatch.src.Description
);
throw new Exception(msg);
}
}