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#region License
// Copyright (c) 2007 James Newton-King
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
#endregion
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Reflection;
using System.Runtime.Serialization;
using Newtonsoft.Json.Utilities;
namespace Newtonsoft.Json.Converters
{
/// <summary>
/// Converts an <see cref="Enum"/> to and from its name string value.
/// </summary>
/// <summary>
/// Converts an <see cref="Enum"/> to and from its name string value.
/// </summary>
public class StringEnumConverter : JsonConverter
{
private readonly Dictionary<Type, BidirectionalDictionary<string, string>> _enumMemberNamesPerType = new Dictionary<Type, BidirectionalDictionary<string, string>>();
/// <summary>
/// Gets or sets a value indicating whether the written enum text should be camel case.
/// </summary>
/// <value><c>true</c> if the written enum text will be camel case; otherwise, <c>false</c>.</value>
public bool CamelCaseText { get; set; }
/// <summary>
/// Writes the JSON representation of the object.
/// </summary>
/// <param name="writer">The <see cref="JsonWriter"/> to write to.</param>
/// <param name="value">The value.</param>
/// <param name="serializer">The calling serializer.</param>
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
if (value == null)
{
writer.WriteNull();
return;
}
Enum e = (Enum)value;
string enumName = e.ToString("G");
if (char.IsNumber(enumName[0]) || enumName[0] == '-')
{
writer.WriteValue(value);
}
else
{
BidirectionalDictionary<string, string> map = GetEnumNameMap(e.GetType());
string resolvedEnumName;
map.TryGetByFirst(enumName, out resolvedEnumName);
resolvedEnumName = resolvedEnumName ?? enumName;
if (CamelCaseText)
{
string[] names = resolvedEnumName.Split(',').Select(item => StringUtils.ToCamelCase(item.Trim())).ToArray();
resolvedEnumName = string.Join(", ", names);
}
writer.WriteValue(resolvedEnumName);
}
}
/// <summary>
/// Reads the JSON representation of the object.
/// </summary>
/// <param name="reader">The <see cref="JsonReader"/> to read from.</param>
/// <param name="objectType">Type of the object.</param>
/// <param name="existingValue">The existing value of object being read.</param>
/// <param name="serializer">The calling serializer.</param>
/// <returns>The object value.</returns>
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
Type t = (ReflectionUtils.IsNullableType(objectType))
? Nullable.GetUnderlyingType(objectType)
: objectType;
if (reader.TokenType == JsonToken.Null)
{
if (!ReflectionUtils.IsNullableType(objectType))
throw new Exception("Cannot convert null value to {0}.".FormatWith(CultureInfo.InvariantCulture, objectType));
return null;
}
if (reader.TokenType == JsonToken.String)
{
var map = GetEnumNameMap(t);
string resolvedEnumName;
map.TryGetBySecond(reader.Value.ToString(), out resolvedEnumName);
resolvedEnumName = resolvedEnumName ?? reader.Value.ToString();
return Enum.Parse(t, resolvedEnumName, true);
}
if (reader.TokenType == JsonToken.Integer)
return ConvertUtils.ConvertOrCast(reader.Value, CultureInfo.InvariantCulture, t);
throw new Exception("Unexpected token when parsing enum. Expected String or Integer, got {0}.".FormatWith(CultureInfo.InvariantCulture, reader.TokenType));
}
/// <summary>
/// A cached representation of the Enum string representation to respect per Enum field name.
/// </summary>
/// <param name="t">The type of the Enum.</param>
/// <returns>A map of enum field name to either the field name, or the configured enum member name (<see cref="EnumMemberAttribute"/>).</returns>
private BidirectionalDictionary<string, string> GetEnumNameMap(Type t)
{
BidirectionalDictionary<string, string> map;
if (!_enumMemberNamesPerType.TryGetValue(t, out map))
{
lock (_enumMemberNamesPerType)
{
if (_enumMemberNamesPerType.TryGetValue(t, out map))
return map;
map = new BidirectionalDictionary<string, string>(
StringComparer.OrdinalIgnoreCase,
StringComparer.OrdinalIgnoreCase);
foreach (FieldInfo f in t.GetFields())
{
string n1 = f.Name;
string n2;
#if !NET20
n2 = f.GetCustomAttributes(typeof (EnumMemberAttribute), true)
.Cast<EnumMemberAttribute>()
.Select(a => a.Value)
.SingleOrDefault() ?? f.Name;
#else
n2 = f.Name;
#endif
string s;
if (map.TryGetBySecond(n2, out s))
{
throw new Exception("Enum name '{0}' already exists on enum '{1}'."
.FormatWith(CultureInfo.InvariantCulture, n2, t.Name));
}
map.Add(n1, n2);
}
_enumMemberNamesPerType[t] = map;
}
}
return map;
}
/// <summary>
/// Determines whether this instance can convert the specified object type.
/// </summary>
/// <param name="objectType">Type of the object.</param>
/// <returns>
/// <c>true</c> if this instance can convert the specified object type; otherwise, <c>false</c>.
/// </returns>
public override bool CanConvert(Type objectType)
{
Type t = (ReflectionUtils.IsNullableType(objectType))
? Nullable.GetUnderlyingType(objectType)
: objectType;
return t.IsEnum();
}
}
}
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