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#region License, Terms and Author(s)
//
// ELMAH - Error Logging Modules and Handlers for ASP.NET
// Copyright (c) 2004-9 Atif Aziz. All rights reserved.
//
// Author(s):
//
// Atif Aziz, http://www.raboof.com
//
// 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.
//
#endregion
[assembly: Elmah.Scc("$Id: JsonTextWriter.cs 640 2009-06-01 17:22:02Z azizatif $")]
namespace Elmah
{
#region Imports
using System;
using System.Globalization;
using System.IO;
using System.Xml;
#endregion
/// <summary>
/// Represents a writer that provides a fast, non-cached, forward-only
/// way of generating streams or files containing JSON Text according
/// to the grammar rules laid out in
/// <a href="http://www.ietf.org/rfc/rfc4627.txt">RFC 4627</a>.
/// </summary>
/// <remarks>
/// This class supports ELMAH and is not intended to be used directly
/// from your code. It may be modified or removed in the future without
/// notice. It has public accessibility for testing purposes. If you
/// need a general-purpose JSON Text encoder, consult
/// <a href="http://www.json.org/">JSON.org</a> for implementations
/// or use classes available from the Microsoft .NET Framework.
/// </remarks>
public sealed class JsonTextWriter
{
private readonly TextWriter _writer;
private readonly int[] _counters;
private readonly char[] _terminators;
private string _memberName;
public JsonTextWriter(TextWriter writer)
{
Debug.Assert(writer != null);
_writer = writer;
const int levels = 10 + /* root */ 1;
_counters = new int[levels];
_terminators = new char[levels];
}
public int Depth { get; private set; }
private int ItemCount
{
get { return _counters[Depth]; }
set { _counters[Depth] = value; }
}
private char Terminator
{
get { return _terminators[Depth]; }
set { _terminators[Depth] = value; }
}
public JsonTextWriter Object()
{
return StartStructured("{", "}");
}
public JsonTextWriter EndObject()
{
return Pop();
}
public JsonTextWriter Array()
{
return StartStructured("[", "]");
}
public JsonTextWriter EndArray()
{
return Pop();
}
public JsonTextWriter Pop()
{
return EndStructured();
}
public JsonTextWriter Member(string name)
{
if (name == null) throw new ArgumentNullException("name");
if (_memberName != null) throw new InvalidOperationException("Missing member value.");
_memberName = name;
return this;
}
private JsonTextWriter Write(string text)
{
return WriteImpl(text, /* raw */ false);
}
private JsonTextWriter WriteEnquoted(string text)
{
return WriteImpl(text, /* raw */ true);
}
private JsonTextWriter WriteImpl(string text, bool raw)
{
Debug.Assert(raw || !string.IsNullOrEmpty(text));
if (Depth == 0 && (text.Length > 1 || (text[0] != '{' && text[0] != '[')))
throw new InvalidOperationException();
var writer = _writer;
if (ItemCount > 0)
writer.Write(',');
var name = _memberName;
_memberName = null;
if (name != null)
{
writer.Write(' ');
Enquote(name, writer);
writer.Write(':');
}
if (Depth > 0)
writer.Write(' ');
if (raw)
Enquote(text, writer);
else
writer.Write(text);
ItemCount = ItemCount + 1;
return this;
}
public JsonTextWriter Number(int value)
{
return Write(value.ToString(CultureInfo.InvariantCulture));
}
public JsonTextWriter String(string str)
{
return str == null ? Null() : WriteEnquoted(str);
}
public JsonTextWriter Null()
{
return Write("null");
}
public JsonTextWriter Boolean(bool value)
{
return Write(value ? "true" : "false");
}
private static readonly DateTime Epoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
public JsonTextWriter Number(DateTime time)
{
var seconds = time.ToUniversalTime().Subtract(Epoch).TotalSeconds;
return Write(seconds.ToString(CultureInfo.InvariantCulture));
}
public JsonTextWriter String(DateTime time)
{
return String(XmlConvert.ToString(time, XmlDateTimeSerializationMode.Utc));
}
private JsonTextWriter StartStructured(string start, string end)
{
if (Depth + 1 == _counters.Length)
throw new Exception();
Write(start);
Depth++;
Terminator = end[0];
return this;
}
private JsonTextWriter EndStructured()
{
if (Depth - 1 < 0)
throw new Exception();
_writer.Write(' ');
_writer.Write(Terminator);
ItemCount = 0;
Depth--;
return this;
}
private static void Enquote(string s, TextWriter writer)
{
Debug.Assert(writer != null);
var length = (s ?? string.Empty).Length;
writer.Write('"');
var ch = '\0';
for (var index = 0; index < length; index++)
{
var last = ch;
Debug.Assert(s != null);
ch = s[index];
switch (ch)
{
case '\\':
case '"':
{
writer.Write('\\');
writer.Write(ch);
break;
}
case '/':
{
if (last == '<')
writer.Write('\\');
writer.Write(ch);
break;
}
case '\b': writer.Write("\\b"); break;
case '\t': writer.Write("\\t"); break;
case '\n': writer.Write("\\n"); break;
case '\f': writer.Write("\\f"); break;
case '\r': writer.Write("\\r"); break;
default:
{
if (ch < ' ')
{
writer.Write("\\u");
writer.Write(((int)ch).ToString("x4", CultureInfo.InvariantCulture));
}
else
{
writer.Write(ch);
}
break;
}
}
}
writer.Write('"');
}
}
}
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