2018-04-02 12:47:30 -04:00
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using PoweredSoft.DynamicLinq.Dal.Pocos;
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using PoweredSoft.DynamicLinq.Helpers;
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Linq.Expressions;
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using System.Text;
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using System.Threading.Tasks;
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namespace PoweredSoft.DynamicLinq.ConsoleApp
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{
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public class BetterProto2
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{
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/*
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* (parent, innerExpression, innerExpressionLambda) =>
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{
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var listGenericArgumentType = parent.Type.GetGenericArguments().First();
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Expression ret = null;
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if (selectCollectionHandling == SelectCollectionHandling.LeaveAsIs || !QueryableHelpers.IsGenericEnumerable(innerExpression))
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ret = Expression.Call(typeof(Enumerable), "Select", new Type[] { listGenericArgumentType, innerExpression.Type }, parent, innerExpressionLambda);
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else
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ret = Expression.Call(typeof(Enumerable), "SelectMany", new Type[] { listGenericArgumentType, innerExpression.Type.GenericTypeArguments.First() }, parent, innerExpressionLambda);
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return ret;
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}
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*/
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public static void Run()
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2018-04-02 15:09:57 -04:00
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{
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//Case1();
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Case2();
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}
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public static void Case1()
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2018-04-02 12:47:30 -04:00
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{
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2018-04-02 12:57:46 -04:00
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// the expression parser.
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2018-04-02 12:47:30 -04:00
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var ep = new ExpressionParser(typeof(Author), "Posts.Comments.Id");
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2018-04-02 12:57:46 -04:00
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// the builder.
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var per = new PathExpressionResolver(ep);
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per.Resolve();
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// the result expression.
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var result = per.Result;
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2018-04-02 12:47:30 -04:00
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}
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2018-04-02 15:09:57 -04:00
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public static void Case2()
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{
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// the expression parser.
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2018-04-02 15:37:49 -04:00
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var ep = new ExpressionParser(typeof(Post), "Author.Posts.Author.FirstName");
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2018-04-02 16:01:35 -04:00
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new List<Post>().AsQueryable().Select(t => new
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2018-04-02 15:37:49 -04:00
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{
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FirstNames = t.Author == null ? new List<string>() : (t.Author.Posts == null ? new List<string>() : t.Author.Posts.Where(t2 => t2.Author != null).Select(t2 => t2.Author.FirstName)),
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Comments = t.Comments == null ? new List<Comment>() : t.Comments,
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CommentLikes = (t.Comments == null ? new List<CommentLike>() : t.Comments.Where(t2 => t2.CommentLikes != null).SelectMany(t2 => t2.CommentLikes)),
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CommentLikeIds = (t.Comments == null ? new List<long>() : t.Comments.Where(t2 => t2.CommentLikes != null).SelectMany(t2 => t2.CommentLikes.Select(t3 => t3.Id))),
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CommentsLikes = (t.Comments == null ? new List<List<CommentLike>>() : t.Comments.Where(t2 => t2.CommentLikes != null).Select(t2 => t2.CommentLikes))
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});
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2018-04-02 15:09:57 -04:00
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// the builder.
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var per = new PathExpressionResolver(ep);
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per.Resolve();
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// the result expression.
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var result = per.Result;
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}
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2018-04-02 12:47:30 -04:00
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}
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public class ExpressionParserPiece
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{
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public Type Type { get; set; }
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public bool IsGenericEnumerable { get; set; }
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public Type EnumerableType { get; set; }
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public ExpressionParserPiece Parent { get; set; }
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}
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2018-04-02 12:57:46 -04:00
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public class PathExpressionResolver
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{
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public SelectNullHandling NullChecking { get; set; } = SelectNullHandling.LeaveAsIs;
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public SelectCollectionHandling CollectionHandling { get; set; } = SelectCollectionHandling.LeaveAsIs;
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public ExpressionParser Parser { get; protected set; }
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public Expression Result { get; protected set; }
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2018-04-02 15:09:57 -04:00
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protected Expression NullCheckValueExpression { get; set; }
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public PathExpressionResolver(ExpressionParser parser)
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{
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Parser = parser;
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}
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public void Resolve()
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{
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Result = null;
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// parse the expression.
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Parser.Parse();
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2018-04-02 15:09:57 -04:00
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// resolve the expression to use during a conditional if null checking is enabled.
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ResolveNullCheckingRightType();
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// reverse foreach
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Parser.Pieces.ReversedForEach((piece, index) =>
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{
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if (piece.Parent == null)
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return;
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if (piece.Parent.IsGenericEnumerable)
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HandleCollection(piece, index);
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});
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}
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2018-04-02 15:09:57 -04:00
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private void ResolveNullCheckingRightType()
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{
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if (NullChecking == SelectNullHandling.LeaveAsIs)
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return;
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2018-04-02 15:37:49 -04:00
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// last piece.
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var lastPiece = Parser.Pieces.Last();
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// the subject type
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Type subjectType = null;
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if (lastPiece.IsGenericEnumerable)
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subjectType = typeof(List<>).MakeGenericType(lastPiece.EnumerableType);
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if (NullChecking == SelectNullHandling.Default)
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NullCheckValueExpression = Expression.Default(subjectType);
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else
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NullCheckValueExpression = Expression.New(subjectType);
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2018-04-02 15:09:57 -04:00
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}
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private void HandleCollection(ExpressionParserPiece piece, int index)
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{
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2018-04-02 16:01:35 -04:00
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2018-04-02 15:09:57 -04:00
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/*
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if (Result == null)
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HandleNoPreviousResultCollection(piece, index);
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else
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HandlePreviousResultCollection(piece, index);*/
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}
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/*
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public void HandleNoPreviousResultCollection(ExpressionParserPiece piece, int index)
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{
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MethodCallExpression result = null;
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// create the lambda.
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var lambda = ResolveLambda(piece);
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if (CollectionHandling == SelectCollectionHandling.LeaveAsIs || !piece.IsGenericEnumerable)
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result = Expression.Call(typeof(Enumerable),
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"Select",
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new Type[] { piece.Parent.EnumerableType, piece.MemberExpression.Type },
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piece.Parent.MemberExpression, lambda);
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else
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result = Expression.Call(typeof(Enumerable),
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"SelectMany",
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new Type[] { piece.Parent.EnumerableType, piece.EnumerableType },
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piece.Parent.MemberExpression, lambda);
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Result = result;
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}
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public void HandlePreviousResultCollection(ExpressionParserPiece piece, int index)
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{
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var pieceParameter = ResolvePieceParameter(piece);
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MethodCallExpression result = null;
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var lambda = Expression.Lambda(Result, ResolvePieceParameter(piece));
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if (CollectionHandling == SelectCollectionHandling.LeaveAsIs)
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result = Expression.Call(typeof(Enumerable), "Select",
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new Type[] { piece.Parent.EnumerableType, Result.Type },
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piece.Parent.MemberExpression, lambda);
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else
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result = Expression.Call(typeof(Enumerable),
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"SelectMany",
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new Type[] { piece.Parent.EnumerableType, Result.Type.GenericTypeArguments.First() },
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piece.Parent.MemberExpression, lambda);
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Result = result;
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}*/
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2018-04-02 12:57:46 -04:00
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}
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2018-04-02 12:47:30 -04:00
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public class ExpressionParser
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{
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public ParameterExpression Parameter { get; protected set; }
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public string Path { get; set; }
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public List<ExpressionParserPiece> Pieces { get; set; } = new List<ExpressionParserPiece>();
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public ExpressionParser(Type type, string path) : this(Expression.Parameter(type), path)
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{
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}
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public ExpressionParser(ParameterExpression parameter, string path)
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{
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Parameter = parameter;
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Path = path;
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}
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public void Parse()
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{
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Pieces.Clear();
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var pathPieces = Path.Split('.').ToList();
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var param = Parameter;
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ExpressionParserPiece parent = null;
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pathPieces.ForEach(pp =>
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{
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var memberExpression = Expression.PropertyOrField(param, pp);
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var current = new ExpressionParserPiece
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{
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Type = memberExpression.Type,
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IsGenericEnumerable = QueryableHelpers.IsGenericEnumerable(memberExpression),
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EnumerableType = memberExpression.Type.GenericTypeArguments.FirstOrDefault(),
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Parent = parent
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};
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Pieces.Add(current);
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2018-04-02 15:09:57 -04:00
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// for next iteration.
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param = Expression.Parameter(current.IsGenericEnumerable ? current.EnumerableType : current.Type);
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parent = current;
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});
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}
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}
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}
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