dotnet-dynamic-linq/PoweredSoft.DynamicLinq.ConsoleApp/BetterParserProto1.cs
2018-04-02 11:47:30 -05:00

231 lines
8.8 KiB
C#

using PoweredSoft.DynamicLinq.Dal.Pocos;
using PoweredSoft.DynamicLinq.Helpers;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;
#if false
namespace PoweredSoft.DynamicLinq.ConsoleApp
{
public class StaticProto1
{
public static void Run()
{
var q = new List<Author>().AsQueryable();
q.Select(t => new
{
Ids = t.Posts.SelectMany(t2 => t2.Comments.Select(t3 => t3.CommentLikes))
});
var expressionParser = new ExpressionParser(typeof(Author), "Posts.Comments.CommentLikes");
expressionParser.Parse();
var finalExpression = CreateSelectExpressionFromParsed(expressionParser, SelectCollectionHandling.Flatten, SelectNullHandling.New);
}
public static Expression CreateSelectExpressionFromParsed(ExpressionParser expressionParser,
SelectCollectionHandling selectCollectionHandling = SelectCollectionHandling.LeaveAsIs,
SelectNullHandling nullChecking = SelectNullHandling.LeaveAsIs)
{
Type nullHandlingRightType = null;
Expression nullHandlingNullValue = null;
if (nullChecking != SelectNullHandling.LeaveAsIs)
{
var withoutNullCheckResult = CreateSelectExpressionFromParsed(expressionParser, SelectCollectionHandling.Flatten, SelectNullHandling.LeaveAsIs);
if (QueryableHelpers.IsGenericEnumerable(withoutNullCheckResult.Type))
nullHandlingRightType = typeof(List<>).MakeGenericType(withoutNullCheckResult.Type.GenericTypeArguments.First());
else
nullHandlingRightType = withoutNullCheckResult.Type;
nullHandlingNullValue = nullChecking == SelectNullHandling.Default
? Expression.Default(nullHandlingRightType) as Expression
: Expression.New(nullHandlingRightType) as Expression;
}
// reversed :)
var reversedCopy = expressionParser.Groups.Select(t => t).ToList();
reversedCopy.Reverse();
MethodCallExpression lastSelectExpression = null;
Expression ret = null;
foreach (var t in reversedCopy)
{
if (true == t.Parent?.LastPiece().IsGenericEnumerable())
{
if (lastSelectExpression == null)
lastSelectExpression = RegroupSelectExpressions(t, selectCollectionHandling);
else
lastSelectExpression = RegroupSelectExpressions(t, lastSelectExpression, selectCollectionHandling);
}
}
ret = lastSelectExpression;
return ret;
}
public static MethodCallExpression RegroupSelectExpressions(ExpressionParameterGroup group, SelectCollectionHandling selectCollectionHandling)
{
MethodCallExpression ret = null;
var lambda = group.CreateLambda();
var parentExpression = group.Parent.LastExpression();
var isParentExpressionGenericEnumerable = QueryableHelpers.IsGenericEnumerable(parentExpression);
var parentExpressionGenericEnumerableType = isParentExpressionGenericEnumerable ? parentExpression.Type.GenericTypeArguments.First() : null;
var lastPiece = group.LastPiece();
if (selectCollectionHandling == SelectCollectionHandling.LeaveAsIs || !lastPiece.IsGenericEnumerable())
ret = Expression.Call(typeof(Enumerable), "Select", new Type[] { parentExpressionGenericEnumerableType, lastPiece.Expression.Type }, parentExpression, lambda);
else
ret = Expression.Call(typeof(Enumerable), "SelectMany", new Type[] { parentExpressionGenericEnumerableType, lastPiece.GetGenericEnumerableType() }, parentExpression, lambda);
return ret;
}
public static MethodCallExpression RegroupSelectExpressions(ExpressionParameterGroup group, MethodCallExpression innerSelect, SelectCollectionHandling selectCollectionHandling)
{
var parent = group.Parent;
var parentLastPiece = parent.LastPiece();
MethodCallExpression ret = null;
var lambda = Expression.Lambda(innerSelect, group.Parameter);
if (selectCollectionHandling == SelectCollectionHandling.LeaveAsIs)
ret = Expression.Call(typeof(Enumerable), "Select", new Type[] { parentLastPiece.GetGenericEnumerableType(), innerSelect.Type }, parentLastPiece.Expression, lambda);
else
ret = Expression.Call(typeof(Enumerable), "SelectMany", new Type[] { parentLastPiece.GetGenericEnumerableType(), innerSelect.Type.GenericTypeArguments.First() }, parentLastPiece.Expression, lambda);
return ret;
}
}
public class ExpressionParameterGroup
{
public ExpressionParameterGroup Parent { get; set; }
public ParameterExpression Parameter { get; set; }
public List<ExpressionPiece> Pieces { get; set; } = new List<ExpressionPiece>();
public ExpressionParameterGroup(ParameterExpression parameter)
{
Parameter = parameter;
}
public void AddSubPart(ExpressionPiece expressionPart)
{
Pieces.Add(expressionPart);
}
public Expression LastExpression() => LastPiece().Expression;
public ExpressionPiece LastPiece() => Pieces.Last();
public LambdaExpression CreateLambda()
{
var lastExpression = LastPiece().Expression;
var lambda = Expression.Lambda(lastExpression, Parameter);
return lambda;
}
}
public class ExpressionPiece
{
public ExpressionParameterGroup Parameter { get; set; }
public ExpressionPiece Parent { get; set; }
public Expression Expression { get; set; }
public ExpressionPiece(ExpressionParameterGroup parameter, ExpressionPiece parent = null)
{
Parameter = parameter;
Parent = parent;
}
public void Resolve(string piece)
{
Expression = Expression.PropertyOrField(Parent?.Expression ?? Parameter.Parameter, piece);
}
public bool IsGenericEnumerable() => QueryableHelpers.IsGenericEnumerable(Expression);
public Type GetGenericEnumerableType() => Expression.Type.GenericTypeArguments.First();
}
public class ExpressionParser
{
public ParameterExpression Parameter { get; protected set; }
public string Path { get; protected set; }
public List<ExpressionParameterGroup> Groups { get; set; } = new List<ExpressionParameterGroup>();
public ExpressionParser(Type type, string path) : this(Expression.Parameter(type), path)
{
}
public ExpressionParser(ParameterExpression parameter, string path)
{
if (parameter == null)
throw new ArgumentNullException("parameter");
if (string.IsNullOrEmpty(path))
throw new ArgumentNullException("path");
Parameter = parameter;
Path = path;
}
public void Parse()
{
Groups = new List<ExpressionParameterGroup>();
var pieces = Path.Split('.').ToList();
// create the current parameter.
var currentGroup = CreateAndAddParameterGroup(Parameter);
ExpressionPiece parentPiece = null;
int indexOfPiece = -1;
pieces.ForEach(piece =>
{
++indexOfPiece;
bool isLast = indexOfPiece == pieces.Count - 1;
var expressionPiece = new ExpressionPiece(currentGroup, parentPiece);
expressionPiece.Resolve(piece);
currentGroup.AddSubPart(expressionPiece);
// rest is only if its not the last piece.
if (isLast) return;
if (expressionPiece.IsGenericEnumerable())
{
var param = Expression.Parameter(expressionPiece.GetGenericEnumerableType());
currentGroup = CreateAndAddParameterGroup(param, currentGroup);
parentPiece = null;
}
else
{
parentPiece = expressionPiece;
}
});
}
public ExpressionParameterGroup CreateAndAddParameterGroup(ParameterExpression parameter, ExpressionParameterGroup parent = null)
{
var group = new ExpressionParameterGroup(parameter);
if (parent != null)
group.Parent = parent;
Groups.Add(group);
return group;
}
public ExpressionParameterGroup LastGroup()
{
return this.Groups.Last();
}
}
#endif