Rewrite SearchConditionConverter

src/EFCore.SqlServer/Query/Internal/SearchConditionConverter.cs

@@ -0,0 +1,316 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.EntityFrameworkCore.Query.SqlExpressions;
+
+namespace Microsoft.EntityFrameworkCore.SqlServer.Query.Internal;
+
+/// <summary>
+///     <para>
+///         A SQL Server visitor which converts boolean expressions that represent search conditions to bit values and vice versa, depending
+///         on context:
+///     </para>
+///     <code>
+///         WHERE b.SomeBitColumn => WHERE b.SomeBitColumn = 1
+///         SELECT a LIKE b => SELECT CASE WHEN a LIKE b THEN 1 ELSE 0 END
+///     </code>
+/// </summary>
+/// <remarks>
+///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+///     any release. You should only use it directly in your code with extreme caution and knowing that
+///     doing so can result in application failures when updating to a new Entity Framework Core release.
+/// </remarks>
+public class SearchConditionConverter(ISqlExpressionFactory sqlExpressionFactory) : ExpressionVisitor
+{
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    [return: NotNullIfNotNull(nameof(expression))]
+    public override Expression? Visit(Expression? expression)
+        => Visit(expression, inSearchConditionContext: false);
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    [return: NotNullIfNotNull(nameof(expression))]
+    protected virtual Expression? Visit(Expression? expression, bool inSearchConditionContext)
+        => expression switch
+        {
+            CaseExpression e => VisitCase(e, inSearchConditionContext),
+            SelectExpression e => VisitSelect(e),
+            SqlBinaryExpression e => VisitSqlBinary(e, inSearchConditionContext),
+            SqlUnaryExpression e => VisitSqlUnary(e, inSearchConditionContext),
+            PredicateJoinExpressionBase e => VisitPredicateJoin(e),
+
+            // The following are search condition expressions: they can appear directly in a WHERE, and cannot e.g. be projected out
+            // directly
+            SqlExpression e and
+                (ExistsExpression or InExpression or LikeExpression or SqlFunctionExpression { Name: "FREETEXT" or "CONTAINS" })
+                => ApplyConversion((SqlExpression)base.VisitExtension(e), inSearchConditionContext, isExpressionSearchCondition: true),
+
+            SqlExpression e => ApplyConversion(
+                (SqlExpression)base.VisitExtension(e), inSearchConditionContext, isExpressionSearchCondition: false),
+
+            _ => base.Visit(expression)
+        };
+
+    private SqlExpression ApplyConversion(SqlExpression sqlExpression, bool inSearchConditionContext, bool isExpressionSearchCondition)
+        => (inSearchCondition: inSearchConditionContext, isExpressionSearchCondition) switch
+        {
+            // A non-search condition expression in a search condition context - add equality to convert to search condition:
+            // WHERE b.SomeBitColumn => WHERE b.SomeBitColumn = 1
+            (true, false) => sqlExpression is SqlConstantExpression { Value: bool boolValue }
+                ? sqlExpressionFactory.Equal(
+                    boolValue
+                        ? sqlExpressionFactory.Constant(1)
+                        : sqlExpressionFactory.Constant(0),
+                    sqlExpressionFactory.Constant(1))
+                : sqlExpressionFactory.Equal(sqlExpression, sqlExpressionFactory.Constant(true)),
+
+            // A search condition expression in non-search condition context - wrap in CASE/WHEN to convert to bit:
+            // e.g. SELECT a LIKE b => SELECT CASE WHEN a LIKE b THEN 1 ELSE 0 END
+            (false, true) => sqlExpressionFactory.Case(
+                [
+                    new CaseWhenClause(
+                        SimplifyNegatedBinary(sqlExpression),
+                        sqlExpressionFactory.ApplyDefaultTypeMapping(sqlExpressionFactory.Constant(true)))
+                ],
+                sqlExpressionFactory.Constant(false)),
+
+            // All other cases (e.g. WHERE a LIKE b, SELECT b.SomebitColumn) - no need to do anything.
+            _ => sqlExpression
+        };
+
+    private SqlExpression SimplifyNegatedBinary(SqlExpression sqlExpression)
+    {
+        if (sqlExpression is SqlUnaryExpression { OperatorType: ExpressionType.Not } sqlUnaryExpression
+            && sqlUnaryExpression.Type == typeof(bool)
+            && sqlUnaryExpression.Operand is SqlBinaryExpression
+            {
+                OperatorType: ExpressionType.Equal
+            } sqlBinaryOperand)
+        {
+            if (sqlBinaryOperand.Left.Type == typeof(bool)
+                && sqlBinaryOperand.Right.Type == typeof(bool)
+                && (sqlBinaryOperand.Left is SqlConstantExpression
+                    || sqlBinaryOperand.Right is SqlConstantExpression))
+            {
+                var constant = sqlBinaryOperand.Left as SqlConstantExpression ?? (SqlConstantExpression)sqlBinaryOperand.Right;
+                if (sqlBinaryOperand.Left is SqlConstantExpression)
+                {
+                    return sqlExpressionFactory.MakeBinary(
+                        ExpressionType.Equal,
+                        sqlExpressionFactory.Constant(!(bool)constant.Value!, constant.TypeMapping),
+                        sqlBinaryOperand.Right,
+                        sqlBinaryOperand.TypeMapping)!;
+                }
+
+                return sqlExpressionFactory.MakeBinary(
+                    ExpressionType.Equal,
+                    sqlBinaryOperand.Left,
+                    sqlExpressionFactory.Constant(!(bool)constant.Value!, constant.TypeMapping),
+                    sqlBinaryOperand.TypeMapping)!;
+            }
+
+            return sqlExpressionFactory.MakeBinary(
+                sqlBinaryOperand.OperatorType == ExpressionType.Equal
+                    ? ExpressionType.NotEqual
+                    : ExpressionType.Equal,
+                sqlBinaryOperand.Left,
+                sqlBinaryOperand.Right,
+                sqlBinaryOperand.TypeMapping)!;
+        }
+
+        return sqlExpression;
+    }
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    protected virtual Expression VisitCase(CaseExpression caseExpression, bool inSearchConditionContext)
+    {
+        var testIsCondition = caseExpression.Operand is null;
+        var operand = (SqlExpression?)Visit(caseExpression.Operand);
+        var whenClauses = new List<CaseWhenClause>();
+        foreach (var whenClause in caseExpression.WhenClauses)
+        {
+            var test = (SqlExpression)Visit(whenClause.Test, testIsCondition);
+            var result = (SqlExpression)Visit(whenClause.Result);
+            whenClauses.Add(new CaseWhenClause(test, result));
+        }
+
+        var elseResult = (SqlExpression?)Visit(caseExpression.ElseResult);
+
+        return ApplyConversion(
+            sqlExpressionFactory.Case(operand, whenClauses, elseResult, caseExpression),
+            inSearchConditionContext,
+            isExpressionSearchCondition: false);
+    }
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    protected virtual Expression VisitPredicateJoin(PredicateJoinExpressionBase join)
+        => join.Update(
+            (TableExpressionBase)Visit(join.Table),
+            (SqlExpression)Visit(join.JoinPredicate, inSearchConditionContext: true));
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    protected virtual Expression VisitSelect(SelectExpression select)
+    {
+        var tables = this.VisitAndConvert(select.Tables);
+        var predicate = (SqlExpression?)Visit(select.Predicate, inSearchConditionContext: true);
+        var groupBy = this.VisitAndConvert(select.GroupBy);
+        var havingExpression = (SqlExpression?)Visit(select.Having, inSearchConditionContext: true);
+        var projections = this.VisitAndConvert(select.Projection);
+        var orderings = this.VisitAndConvert(select.Orderings);
+        var offset = (SqlExpression?)Visit(select.Offset);
+        var limit = (SqlExpression?)Visit(select.Limit);
+
+        return select.Update(tables, predicate, groupBy, havingExpression, projections, orderings, offset, limit);
+    }
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    protected virtual Expression VisitSqlBinary(SqlBinaryExpression binary, bool inSearchConditionContext)
+    {
+        // Only logical operations need conditions on both sides
+        var areOperandsInSearchConditionContext = binary.OperatorType is ExpressionType.AndAlso or ExpressionType.OrElse;
+
+        var newLeft = (SqlExpression)Visit(binary.Left, areOperandsInSearchConditionContext);
+        var newRight = (SqlExpression)Visit(binary.Right, areOperandsInSearchConditionContext);
+
+        if (binary.OperatorType is ExpressionType.NotEqual or ExpressionType.Equal)
+        {
+            if (!inSearchConditionContext
+                && (newLeft.Type == typeof(bool) || newLeft.Type.IsEnum || newLeft.Type.IsInteger())
+                && (newRight.Type == typeof(bool) || newRight.Type.IsEnum || newRight.Type.IsInteger()))
+            {
+                // "lhs != rhs" is the same as "CAST(lhs ^ rhs AS BIT)", except that
+                // the first is a boolean, the second is a BIT
+                var result = sqlExpressionFactory.MakeBinary(ExpressionType.ExclusiveOr, newLeft, newRight, null)!;
+
+                if (result.Type != typeof(bool))
+                {
+                    result = sqlExpressionFactory.Convert(result, typeof(bool), binary.TypeMapping);
+                }
+
+                // "lhs == rhs" is the same as "NOT(lhs != rhs)" aka "~(lhs ^ rhs)"
+                if (binary.OperatorType is ExpressionType.Equal)
+                {
+                    result = sqlExpressionFactory.MakeUnary(ExpressionType.OnesComplement, result, result.Type, result.TypeMapping)!;
+                }
+
+                return result;
+            }
+
+            if (newLeft is SqlUnaryExpression { OperatorType: ExpressionType.OnesComplement } negatedLeft
+                && newRight is SqlUnaryExpression { OperatorType: ExpressionType.OnesComplement } negatedRight)
+            {
+                newLeft = negatedLeft.Operand;
+                newRight = negatedRight.Operand;
+            }
+        }
+
+        binary = binary.Update(newLeft, newRight);
+
+        var isExpressionSearchCondition = binary.OperatorType is ExpressionType.AndAlso
+            or ExpressionType.OrElse
+            or ExpressionType.Equal
+            or ExpressionType.NotEqual
+            or ExpressionType.GreaterThan
+            or ExpressionType.GreaterThanOrEqual
+            or ExpressionType.LessThan
+            or ExpressionType.LessThanOrEqual;
+
+        return ApplyConversion(binary, inSearchConditionContext, isExpressionSearchCondition);
+    }
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    protected virtual Expression VisitSqlUnary(SqlUnaryExpression sqlUnaryExpression, bool inSearchConditionContext)
+    {
+        bool isOperandInSearchConditionContext, isSearchConditionExpression;
+
+        switch (sqlUnaryExpression.OperatorType)
+        {
+            case ExpressionType.Not when sqlUnaryExpression.Type == typeof(bool):
+            {
+                // when possible, avoid converting to/from predicate form
+                if (!inSearchConditionContext && sqlUnaryExpression.Operand is not (ExistsExpression or InExpression or LikeExpression))
+                {
+                    var negatedOperand = (SqlExpression)Visit(sqlUnaryExpression.Operand);
+
+                    if (negatedOperand is SqlUnaryExpression { OperatorType: ExpressionType.OnesComplement } unary)
+                    {
+                        return unary.Operand;
+                    }
+
+                    return sqlExpressionFactory.MakeUnary(
+                        ExpressionType.OnesComplement, negatedOperand, negatedOperand.Type, negatedOperand.TypeMapping)!;
+                }
+
+                isOperandInSearchConditionContext = true;
+                isSearchConditionExpression = true;
+                break;
+            }
+
+            case ExpressionType.Not:
+                isOperandInSearchConditionContext = false;
+                isSearchConditionExpression = false;
+                break;
+
+            case ExpressionType.Convert:
+            case ExpressionType.Negate:
+                isOperandInSearchConditionContext = false;
+                isSearchConditionExpression = false;
+                break;
+
+            case ExpressionType.Equal:
+            case ExpressionType.NotEqual:
+                isOperandInSearchConditionContext = false;
+                isSearchConditionExpression = true;
+                break;
+
+            default:
+                throw new InvalidOperationException(
+                    RelationalStrings.UnsupportedOperatorForSqlExpression(
+                        sqlUnaryExpression.OperatorType, typeof(SqlUnaryExpression)));
+        }
+
+        var operand = (SqlExpression)Visit(sqlUnaryExpression.Operand, isOperandInSearchConditionContext);
+
+        return SimplifyNegatedBinary(
+            ApplyConversion(
+                sqlUnaryExpression.Update(operand),
+                inSearchConditionContext,
+                isSearchConditionExpression));
+    }
+}