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GetItemMethodToAggregationExpressionTranslator.cs
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GetItemMethodToAggregationExpressionTranslator.cs
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/* Copyright 2010-present MongoDB Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
using System;
using System.Linq.Expressions;
using MongoDB.Bson;
using MongoDB.Bson.Serialization;
using MongoDB.Bson.Serialization.Serializers;
using MongoDB.Driver.Linq.Linq3Implementation.Ast;
using MongoDB.Driver.Linq.Linq3Implementation.Ast.Expressions;
using MongoDB.Driver.Linq.Linq3Implementation.ExtensionMethods;
using MongoDB.Driver.Linq.Linq3Implementation.Misc;
using MongoDB.Driver.Linq.Linq3Implementation.Reflection;
namespace MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToAggregationExpressionTranslators.MethodTranslators
{
internal static class GetItemMethodToAggregationExpressionTranslator
{
public static AggregationExpression Translate(TranslationContext context, MethodCallExpression expression)
{
Expression sourceExpression, indexExpression, keyExpression;
if (IsBsonValueGetItemMethodWithIntIndex(expression, out sourceExpression, out indexExpression))
{
var sourceTranslation = ExpressionToAggregationExpressionTranslator.Translate(context, sourceExpression);
var indexTranslation = ExpressionToAggregationExpressionTranslator.Translate(context, indexExpression);
var ast = AstExpression.ArrayElemAt(sourceTranslation.Ast, indexTranslation.Ast);
var valueSerializer = BsonValueSerializer.Instance;
return new AggregationExpression(expression, ast, valueSerializer);
}
if (IsBsonValueGetItemMethodWithStringKey(expression, out sourceExpression, out keyExpression))
{
var sourceTranslation = ExpressionToAggregationExpressionTranslator.Translate(context, sourceExpression);
var keyTranslation = ExpressionToAggregationExpressionTranslator.Translate(context, keyExpression);
var ast = AstExpression.GetField(sourceTranslation.Ast, keyTranslation.Ast);
var valueSerializer = BsonValueSerializer.Instance;
return new AggregationExpression(expression, ast, valueSerializer);
}
if (IsEnumerableGetItemMethodWithIntIndex(expression, out sourceExpression, out indexExpression))
{
var sourceTranslation = ExpressionToAggregationExpressionTranslator.Translate(context, sourceExpression);
var indexTranslation = ExpressionToAggregationExpressionTranslator.Translate(context, indexExpression);
var ast = AstExpression.ArrayElemAt(sourceTranslation.Ast, indexTranslation.Ast);
var serializer = ArraySerializerHelper.GetItemSerializer(sourceTranslation.Serializer);
return new AggregationExpression(expression, ast, serializer);
}
if (IsDictionaryGetItemMethodWithStringKey(expression, out sourceExpression, out keyExpression))
{
var sourceTranslation = ExpressionToAggregationExpressionTranslator.Translate(context, sourceExpression);
var key = keyExpression.GetConstantValue<string>(containingExpression: expression);
var ast = AstExpression.GetField(sourceTranslation.Ast, key); // TODO: verify that dictionary is using Document representation
var valueSerializer = GetDictionaryValueSerializer(sourceTranslation.Serializer);
return new AggregationExpression(expression, ast, valueSerializer);
}
throw new ExpressionNotSupportedException(expression);
}
private static IBsonSerializer GetDictionaryValueSerializer(IBsonSerializer serializer)
{
if (serializer is IBsonDictionarySerializer dictionarySerializer)
{
return dictionarySerializer.ValueSerializer;
}
throw new InvalidOperationException($"Unable to determine value serializer for dictionary serializer: {serializer.GetType().FullName}.");
}
private static bool IsBsonValueGetItemMethodWithIntIndex(MethodCallExpression expression, out Expression sourceExpression, out Expression indexExpression)
{
var method = expression.Method;
var arguments = expression.Arguments;
if (method.Is(BsonValueMethod.GetItemWithInt))
{
sourceExpression = expression.Object;
indexExpression = arguments[0];
return true;
}
sourceExpression = null;
indexExpression = null;
return false;
}
private static bool IsBsonValueGetItemMethodWithStringKey(MethodCallExpression expression, out Expression sourceExpression, out Expression keyExpression)
{
var method = expression.Method;
var arguments = expression.Arguments;
if (method.Is(BsonValueMethod.GetItemWithString))
{
sourceExpression = expression.Object;
keyExpression = arguments[0];
return true;
}
sourceExpression = null;
keyExpression = null;
return false;
}
private static bool IsEnumerableGetItemMethodWithIntIndex(MethodCallExpression expression, out Expression sourceExpression, out Expression indexExpression)
{
var method = expression.Method;
var arguments = expression.Arguments;
if (!method.IsStatic && method.Name == "get_Item")
{
sourceExpression = expression.Object;
indexExpression = arguments[0];
if (sourceExpression.Type.TryGetIEnumerableGenericInterface(out var sourceEnumerableInterface))
{
var sourceItemType = sourceEnumerableInterface.GetGenericArguments()[0];
if (expression.Type == sourceItemType)
{
if (indexExpression.Type == typeof(int))
{
return true;
}
}
}
}
sourceExpression = null;
indexExpression = null;
return false;
}
private static bool IsDictionaryGetItemMethodWithStringKey(MethodCallExpression expression, out Expression sourceExpression, out Expression keyExpression)
{
var method = expression.Method;
var arguments = expression.Arguments;
if (!method.IsStatic && method.Name == "get_Item")
{
sourceExpression = expression.Object;
keyExpression = arguments[0];
if (sourceExpression.Type.TryGetIDictionaryGenericInterface(out var sourceDictionaryInterface))
{
var sourceTypeParameters = sourceDictionaryInterface.GetGenericArguments();
var sourceKeyType = sourceTypeParameters[0];
var sourceValueType = sourceTypeParameters[1];
if (sourceKeyType == typeof(string) && expression.Type == sourceValueType)
{
if (keyExpression.Type == typeof(string))
{
return true;
}
}
}
}
sourceExpression = null;
keyExpression = null;
return false;
}
}
}