private readonly PropertyInfo?count; // if null then object supports Slice method with Range parameter
/// <summary>
/// Initializes a new slice of collection or array.
/// </summary>
/// <param name="collection">The collection or array.</param>
/// <param name="range">The requested range of collection or array. Should of type <see cref="Range"/>.</param>
/// <exception cref="ArgumentException"><paramref name="collection"/> doesn't implement <c>Slice</c> method, <c>Length</c> or <c>Count</c> property; or <paramref name="range"/> is not of type <see cref="Range"/>.</exception>
public SliceExpression(Expression collection, Expression range)
{
if (collection is null)
{
throw new ArgumentNullException(nameof(collection));
}
if (range is null)
{
throw new ArgumentNullException(nameof(range));
}
if (range.Type != typeof(Range))
{
throw new ArgumentException(ExceptionMessages.TypeExpected <Range>(), nameof(range));
}
var resolved = false;
if (collection.Type.IsSZArray)
{
slice = null;
count = null;
resolved = true;
}
else if (collection.Type == typeof(string))
{
slice = new Func <string, Range, string>(StringExtensions.Substring).Method;
count = null;
resolved = true;
}
else
{
foreach (var slice in GetSliceMethods(collection.Type))
{
var parameters = slice.GetParameters();
if (parameters.LongLength == 1L && parameters[0].ParameterType == typeof(Range))
{
count = null;
this.slice = slice;
resolved = true;
break;
}
var intType = typeof(int);
if (parameters.LongLength == 2L && parameters[0].ParameterType == intType && parameters[1].ParameterType == intType)
{
count = CollectionAccessExpression.GetCountProperty(collection.Type) ?? throw new ArgumentException(ExceptionMessages.CollectionExpected(collection.Type), nameof(collection));
this.slice = slice;
resolved = true;
break;
}
}
}
Range = resolved ? range : throw new ArgumentException(ExceptionMessages.CollectionExpected(collection.Type), nameof(collection));
Collection = collection;
}
private readonly PropertyInfo?count; // if null then indexer != null because it has explicit Index parameter type
/// <summary>
/// Initializes a new collection access expression.
/// </summary>
/// <param name="collection">The expression representing collection.</param>
/// <param name="index">The index of the element. Should be of type <see cref="System.Index"/>.</param>
/// <exception cref="ArgumentException"><paramref name="collection"/> doesn't provide implicit support of Index expression.</exception>
/// <seealso href="https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/proposals/csharp-8.0/ranges">Ranges and Indicies</seealso>
public CollectionAccessExpression(Expression collection, Expression index)
{
if (collection is null)
{
throw new ArgumentNullException(nameof(collection));
}
if (index is null)
{
throw new ArgumentNullException(nameof(index));
}
if (index.Type != typeof(Index))
{
throw new ArgumentException(ExceptionMessages.TypeExpected <Index>(), nameof(index));
}
var resolved = false;
if (collection.Type.IsSZArray)
{
indexer = count = null;
resolved = true;
}
else
{
foreach (var indexer in GetIndexers(collection.Type))
{
var parameters = indexer.GetIndexParameters();
if (parameters.LongLength != 1L)
{
continue;
}
var firstParam = parameters[0].ParameterType;
if (firstParam == typeof(Index))
{
count = null;
this.indexer = indexer;
resolved = true;
break;
}
if (firstParam == typeof(int))
{
count = GetCountProperty(collection.Type) ?? throw new ArgumentException(ExceptionMessages.CollectionExpected(collection.Type), nameof(collection));
this.indexer = indexer;
resolved = true;
break;
}
}
}
Index = resolved ? index : throw new ArgumentException(ExceptionMessages.CollectionExpected(collection.Type), nameof(collection));
Collection = collection;
}