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SergeiPavlovSergeiPavlov
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Replace slow Enum.TryParse() by dictionary lookup (#276)
* Replace slow `Enum.TryParse()` by dictionary lookup * Simplify GetQueryableMethod() * reformat * refactor * Return null on unkonwn method
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‎Orm/Xtensive.Orm/Linq/QueryableVisitor.cs

Lines changed: 82 additions & 59 deletions
Original file line numberDiff line numberDiff line change
@@ -4,69 +4,92 @@
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// Created by: Alexis Kochetov
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// Created: 2009.02.25
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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 Xtensive.Reflection;
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namespace Xtensive.Linq
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{
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/// <summary>
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/// Abstract base visitor that handles methods of <see cref="IQueryable"/> and <see cref="IEnumerable{T}"/> by calling <see cref="VisitQueryableMethod"/>.
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/// </summary>
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[Serializable]
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public abstract class QueryableVisitor : ExpressionVisitor
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{
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/// <inheritdoc/>
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protected override Expression VisitMethodCall(MethodCallExpression mc)
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{
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if (mc.Arguments.Count > 0 && mc.Arguments[0].Type == WellKnownTypes.String) {
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return base.VisitMethodCall(mc);
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}
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var method = GetQueryableMethod(mc);
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if (method == null) {
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return base.VisitMethodCall(mc);
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}
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return VisitQueryableMethod(mc, method.Value);
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}
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/// <summary>
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/// Visits method of <see cref="IQueryable"/> or <see cref="IEnumerable{T}"/>.
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/// </summary>
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/// <param name="mc">The method call expression.</param>
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/// <param name="methodKind">Kind of the method.</param>
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protected abstract Expression VisitQueryableMethod(MethodCallExpression mc, QueryableMethodKind methodKind);
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namespace Xtensive.Linq;
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/// <summary>
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/// Parses <see cref="QueryableMethodKind"/> for the specified expression.
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/// </summary>
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/// <param name="call">A call to process.</param>
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/// <returns><see cref="QueryableMethodKind"/> for the specified expression,
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/// or null if method is not a LINQ method.</returns>
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public static QueryableMethodKind? GetQueryableMethod(MethodCallExpression call)
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{
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if (call == null) {
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return null;
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}
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var declaringType = call.Method.DeclaringType;
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if (declaringType == WellKnownTypes.Queryable || declaringType == WellKnownTypes.Enumerable) {
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return ParseQueryableMethodKind(call.Method.Name);
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}
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/// <summary>
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/// Abstract base visitor that handles methods of <see cref="IQueryable"/> and <see cref="IEnumerable{T}"/> by calling <see cref="VisitQueryableMethod"/>.
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/// </summary>
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[Serializable]
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public abstract class QueryableVisitor : ExpressionVisitor
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{
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private static readonly Dictionary<string, QueryableMethodKind> QueryableMethodKindFromName = new() {
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[nameof(Queryable.Aggregate)] = QueryableMethodKind.Aggregate,
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[nameof(Queryable.All)] = QueryableMethodKind.All,
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[nameof(Queryable.Any)] = QueryableMethodKind.Any,
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["AsEnumerable"] = QueryableMethodKind.AsEnumerable,
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["AsQueryable"] = QueryableMethodKind.AsQueryable,
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[nameof(Queryable.Average)] = QueryableMethodKind.Average,
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[nameof(Queryable.Cast)] = QueryableMethodKind.Cast,
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[nameof(Queryable.Concat)] = QueryableMethodKind.Concat,
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[nameof(Queryable.Contains)] = QueryableMethodKind.Contains,
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[nameof(Queryable.Count)] = QueryableMethodKind.Count,
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[nameof(Queryable.DefaultIfEmpty)] = QueryableMethodKind.DefaultIfEmpty,
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[nameof(Queryable.Distinct)] = QueryableMethodKind.Distinct,
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[nameof(Queryable.DistinctBy)] = QueryableMethodKind.DistinctBy,
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[nameof(Queryable.ElementAt)] = QueryableMethodKind.ElementAt,
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[nameof(Queryable.ElementAtOrDefault)] = QueryableMethodKind.ElementAtOrDefault,
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[nameof(Queryable.Except)] = QueryableMethodKind.Except,
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[nameof(Queryable.First)] = QueryableMethodKind.First,
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[nameof(Queryable.FirstOrDefault)] = QueryableMethodKind.FirstOrDefault,
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[nameof(Queryable.GroupBy)] = QueryableMethodKind.GroupBy,
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[nameof(Queryable.GroupJoin)] = QueryableMethodKind.GroupJoin,
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[nameof(Queryable.Intersect)] = QueryableMethodKind.Intersect,
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[nameof(Queryable.Join)] = QueryableMethodKind.Join,
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[nameof(Queryable.Last)] = QueryableMethodKind.Last,
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[nameof(Queryable.LastOrDefault)] = QueryableMethodKind.LastOrDefault,
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[nameof(Queryable.LongCount)] = QueryableMethodKind.LongCount,
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[nameof(Queryable.Max)] = QueryableMethodKind.Max,
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[nameof(Queryable.Min)] = QueryableMethodKind.Min,
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[nameof(Queryable.OfType)] = QueryableMethodKind.OfType,
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[nameof(Queryable.OrderBy)] = QueryableMethodKind.OrderBy,
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[nameof(Queryable.OrderByDescending)] = QueryableMethodKind.OrderByDescending,
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[nameof(Queryable.Reverse)] = QueryableMethodKind.Reverse,
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[nameof(Queryable.Select)] = QueryableMethodKind.Select,
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[nameof(Queryable.SelectMany)] = QueryableMethodKind.SelectMany,
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[nameof(Queryable.SequenceEqual)] = QueryableMethodKind.SequenceEqual,
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[nameof(Queryable.Single)] = QueryableMethodKind.Single,
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[nameof(Queryable.SingleOrDefault)] = QueryableMethodKind.SingleOrDefault,
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[nameof(Queryable.Skip)] = QueryableMethodKind.Skip,
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[nameof(Queryable.SkipWhile)] = QueryableMethodKind.SkipWhile,
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[nameof(Queryable.Sum)] = QueryableMethodKind.Sum,
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[nameof(Queryable.Take)] = QueryableMethodKind.Take,
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[nameof(Queryable.TakeWhile)] = QueryableMethodKind.TakeWhile,
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[nameof(Queryable.ThenBy)] = QueryableMethodKind.ThenBy,
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[nameof(Queryable.ThenByDescending)] = QueryableMethodKind.ThenByDescending,
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["ToArray"] = QueryableMethodKind.ToArray,
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["ToList"] = QueryableMethodKind.ToList,
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[nameof(Queryable.Union)] = QueryableMethodKind.Union,
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[nameof(Queryable.Where)] = QueryableMethodKind.Where
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};
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return null;
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}
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/// <inheritdoc/>
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protected override Expression VisitMethodCall(MethodCallExpression mc) =>
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mc.Arguments is var mcArguments
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&& (mcArguments.Count > 0 && mcArguments[0].Type == WellKnownTypes.String)
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|| !(GetQueryableMethod(mc) is { } method)
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? base.VisitMethodCall(mc)
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: VisitQueryableMethod(mc, method);
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private static QueryableMethodKind? ParseQueryableMethodKind(string methodName)
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{
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if (Enum.TryParse(methodName, out QueryableMethodKind result)) {
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return result;
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}
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/// <summary>
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/// Visits method of <see cref="IQueryable"/> or <see cref="IEnumerable{T}"/>.
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/// </summary>
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/// <param name="mc">The method call expression.</param>
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/// <param name="methodKind">Kind of the method.</param>
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protected abstract Expression VisitQueryableMethod(MethodCallExpression mc, QueryableMethodKind methodKind);
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return null;
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}
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}
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}
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/// <summary>
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/// Parses <see cref="QueryableMethodKind"/> for the specified expression.
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/// </summary>
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/// <param name="call">A call to process.</param>
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/// <returns><see cref="QueryableMethodKind"/> for the specified expression,
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/// or null if method is not a LINQ method.</returns>
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public static QueryableMethodKind? GetQueryableMethod(MethodCallExpression call) =>
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call?.Method.DeclaringType is { } declaringType
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&& (declaringType == WellKnownTypes.Queryable || declaringType == WellKnownTypes.Enumerable)
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&& QueryableMethodKindFromName.TryGetValue(call.Method.Name, out var v)
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? v
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: null;
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}

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