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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 System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
namespace CsvHelper.Expressions
{
/// <summary>
/// Base implementation for classes that write records.
/// </summary>
public abstract class RecordWriter
{
private readonly Dictionary<int, Delegate> typeActions = new Dictionary<int, Delegate>();
/// <summary>
/// Gets the writer.
/// </summary>
protected CsvWriter Writer { get; private set; }
/// <summary>
/// The expression manager.
/// </summary>
protected ExpressionManager ExpressionManager { get; private set; }
/// <summary>
/// Initializes a new instance using the given writer.
/// </summary>
/// <param name="writer">The writer.</param>
public RecordWriter(CsvWriter writer)
{
Writer = writer;
ExpressionManager = ObjectResolver.Current.Resolve<ExpressionManager>(writer);
}
/// <summary>
/// Writes the record to the current row.
/// </summary>
/// <typeparam name="T">Type of the record.</typeparam>
/// <param name="record">The record.</param>
public void Write<T>(T record)
{
try
{
GetWriteDelegate(record)(record);
}
catch (TargetInvocationException ex)
{
if (ex.InnerException != null)
{
throw ex.InnerException;
}
else
{
throw;
}
}
}
/// <summary>
/// Gets the delegate to write the given record.
/// If the delegate doesn't exist, one will be created and cached.
/// </summary>
/// <typeparam name="T">The record type.</typeparam>
/// <param name="record">The record.</param>
protected Action<T> GetWriteDelegate<T>(T record)
{
var type = typeof(T);
var typeKeyName = type.AssemblyQualifiedName;
if (type == typeof(object))
{
type = record.GetType();
typeKeyName += $"|{type.AssemblyQualifiedName}";
}
int typeKey = typeKeyName.GetHashCode();
if (!typeActions.TryGetValue(typeKey, out Delegate action))
{
typeActions[typeKey] = action = CreateWriteDelegate(record);
}
return (Action<T>)action;
}
/// <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 abstract Action<T> CreateWriteDelegate<T>(T record);
/// <summary>
/// Combines the delegates into a single multicast delegate.
/// This is needed because Silverlight doesn't have the
/// Delegate.Combine( params Delegate[] ) overload.
/// </summary>
/// <param name="delegates">The delegates to combine.</param>
/// <returns>A multicast delegate combined from the given delegates.</returns>
protected virtual Action<T> CombineDelegates<T>(IEnumerable<Action<T>> delegates)
{
return (Action<T>)delegates.Aggregate<Delegate, Delegate>(null, Delegate.Combine);
}
}
}
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