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// Copyright 2009-2022 Josh Close
// This file is a part of CsvHelper and is dual licensed under MS-PL and Apache 2.0.
// See LICENSE.txt for details or visit http://www.opensource.org/licenses/ms-pl.html for MS-PL and http://opensource.org/licenses/Apache-2.0 for Apache 2.0.
// https://github.com/JoshClose/CsvHelper
using CsvHelper.Configuration;
using CsvHelper.TypeConversion;
using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;
namespace CsvHelper.Expressions
{
/// <summary>
/// Writes objects.
/// </summary>
public class ObjectRecordWriter : RecordWriter
{
/// <summary>
/// Initializes a new instance using the given writer.
/// </summary>
/// <param name="writer">The writer.</param>
public ObjectRecordWriter(CsvWriter writer) : base(writer) { }
/// <summary>
/// Creates a <see cref="Delegate"/> of type <see cref="Action{T}"/>
/// that will write the given record using the current writer row.
/// </summary>
/// <typeparam name="T">The record type.</typeparam>
/// <param name="record">The record.</param>
protected override Action<T> CreateWriteDelegate<T>(T record)
{
var type = Writer.GetTypeForRecord(record);
if (Writer.Context.Maps[type] == null)
{
Writer.Context.Maps.Add(Writer.Context.AutoMap(type));
}
var recordParameter = Expression.Parameter(typeof(T), "record");
var recordParameterConverted = Expression.Convert(recordParameter, type);
// Get a list of all the members so they will
// be sorted properly.
var members = new MemberMapCollection();
members.AddMembers(Writer.Context.Maps[type]);
if (members.Count == 0)
{
throw new WriterException(Writer.Context, $"No properties are mapped for type '{type.FullName}'.");
}
var delegates = new List<Action<T>>();
foreach (var memberMap in members)
{
if (memberMap.Data.WritingConvertExpression != null)
{
// The user is providing the expression to do the conversion.
var constructor = typeof(ConvertToStringArgs<T>).GetConstructor(new Type[] { typeof(T) });
var args = Expression.New(constructor, recordParameterConverted);
Expression exp = Expression.Invoke(memberMap.Data.WritingConvertExpression, args);
exp = Expression.Call(Expression.Constant(Writer), nameof(Writer.WriteField), null, exp);
delegates.Add(Expression.Lambda<Action<T>>(exp, recordParameter).Compile());
continue;
}
if (!Writer.CanWrite(memberMap))
{
continue;
}
Expression fieldExpression;
if (memberMap.Data.IsConstantSet)
{
if (memberMap.Data.Constant == null)
{
fieldExpression = Expression.Constant(string.Empty);
}
else
{
fieldExpression = Expression.Constant(memberMap.Data.Constant);
var typeConverterExpression = Expression.Constant(Writer.Context.TypeConverterCache.GetConverter(memberMap.Data.Constant.GetType()));
var method = typeof(ITypeConverter).GetMethod(nameof(ITypeConverter.ConvertToString));
fieldExpression = Expression.Convert(fieldExpression, typeof(object));
fieldExpression = Expression.Call(typeConverterExpression, method, fieldExpression, Expression.Constant(Writer), Expression.Constant(memberMap.Data));
}
}
else
{
if (memberMap.Data.TypeConverter == null)
{
// Skip if the type isn't convertible.
continue;
}
fieldExpression = ExpressionManager.CreateGetMemberExpression(recordParameterConverted, Writer.Context.Maps[type], memberMap);
var typeConverterExpression = Expression.Constant(memberMap.Data.TypeConverter);
memberMap.Data.TypeConverterOptions = TypeConverterOptions.Merge(new TypeConverterOptions { CultureInfo = Writer.Configuration.CultureInfo }, Writer.Context.TypeConverterOptionsCache.GetOptions(memberMap.Data.Member.MemberType()), memberMap.Data.TypeConverterOptions);
var method = typeof(ITypeConverter).GetMethod(nameof(ITypeConverter.ConvertToString));
fieldExpression = Expression.Convert(fieldExpression, typeof(object));
fieldExpression = Expression.Call(typeConverterExpression, method, fieldExpression, Expression.Constant(Writer), Expression.Constant(memberMap.Data));
if (type.GetTypeInfo().IsClass)
{
var areEqualExpression = Expression.Equal(recordParameterConverted, Expression.Constant(null));
fieldExpression = Expression.Condition(areEqualExpression, Expression.Constant(string.Empty), fieldExpression);
}
}
var writeFieldMethodCall = Expression.Call(Expression.Constant(Writer), nameof(Writer.WriteConvertedField), null, fieldExpression, Expression.Constant(memberMap.Data.Type));
delegates.Add(Expression.Lambda<Action<T>>(writeFieldMethodCall, recordParameter).Compile());
}
var action = CombineDelegates(delegates) ?? new Action<T>((T parameter) => { });
return action;
}
}
}
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