using System;
using System.Collections.Generic;
using System.Globalization;
using NewLife.Collections;
namespace NewLife.Serialization
{
/// <summary>Json分析器</summary>
public class JsonParser
{
#region 内部
/// <summary>标识符</summary>
enum Token
{
None = -1,
/// <summary>左大括号</summary>
Curly_Open,
/// <summary>右大括号</summary>
Curly_Close,
/// <summary>左方括号</summary>
Squared_Open,
/// <summary>右方括号</summary>
Squared_Close,
/// <summary>冒号</summary>
Colon,
/// <summary>逗号</summary>
Comma,
/// <summary>字符串</summary>
String,
/// <summary>数字</summary>
Number,
/// <summary>布尔真</summary>
True,
/// <summary>布尔真</summary>
False,
/// <summary>空值</summary>
Null
}
#endregion
#region 属性
readonly String _json;
//readonly StringBuilder _builder = new StringBuilder();
Token _Ahead = Token.None;
Int32 index;
#endregion
/// <summary>实例化</summary>
/// <param name="json"></param>
public JsonParser(String json) => _json = json;
/// <summary>解码</summary>
/// <returns></returns>
public Object Decode() => ParseValue();
private Dictionary<String, Object> ParseObject()
{
var dic = new NullableDictionary<String, Object>(StringComparer.OrdinalIgnoreCase);
SkipToken(); // {
while (true)
{
var old = index;
var token = LookAhead();
switch (token)
{
case Token.Comma:
SkipToken();
break;
case Token.Curly_Close:
SkipToken();
return dic;
default:
{
// 如果名称是数字，需要退回去
if (token == Token.Number) index = old;
// 名称
var name = ParseName();
// :
if (NextToken() != Token.Colon)
{
// "//"开头的是注释，跳过
if (name.TrimStart().StartsWith("//"))
{
break;
}
throw new XException("在 {0} 后需要冒号", name);
}
// 值
dic[name] = ParseValue();
}
break;
}
}
}
private List<Object> ParseArray()
{
var arr = new List<Object>();
SkipToken(); // [
while (true)
{
switch (LookAhead())
{
case Token.Comma:
SkipToken();
break;
case Token.Squared_Close:
SkipToken();
return arr;
default:
arr.Add(ParseValue());
break;
}
}
}
private Object ParseValue()
{
switch (LookAhead())
{
case Token.Number:
return ParseNumber();
case Token.String:
var str = ParseString();
if (str.IsNullOrEmpty()) return str;
// 有可能是字符串或时间日期
if (str[0] == '/' && str[str.Length - 1] == '/' && str.StartsWithIgnoreCase("/Date(") && str.EndsWithIgnoreCase(")/"))
{
str = str.Substring(6, str.Length - 6 - 2);
return str.ToLong().ToDateTime();
}
return str;
case Token.Curly_Open:
return ParseObject();
case Token.Squared_Open:
return ParseArray();
case Token.True:
SkipToken();
return true;
case Token.False:
SkipToken();
return false;
case Token.Null:
SkipToken();
return null;
}
throw new XException("在 {0} 的标识符无法识别", index);
}
private String ParseName()
{
SkipToken(); // "
//_builder.Length = 0;
var sb = Pool.StringBuilder.Get();
var runIndex = -1;
while (index < _json.Length)
{
var c = _json[index++];
if (c == '"')
{
if (runIndex != -1)
{
if (sb.Length == 0) return _json.Substring(runIndex, index - runIndex - 1);
sb.Append(_json, runIndex, index - runIndex - 1);
}
return sb.Put(true);
}
else if (c == ':')
{
// 如果是没有双引号的名字，则退回一个字符
index--;
if (runIndex != -1)
{
if (sb.Length == 0) return _json.Substring(runIndex, index + 1 - runIndex - 1);
sb.Append(_json, runIndex, index + 1 - runIndex - 1);
}
return sb.Put(true);
}
if (c != '\\')
{
if (runIndex == -1) runIndex = index - 1;
continue;
}
if (index == _json.Length) break;
if (runIndex != -1)
{
sb.Append(_json, runIndex, index - runIndex - 1);
runIndex = -1;
}
switch (_json[index++])
{
case '"': sb.Append('"'); break;
case '\\': sb.Append('\\'); break;
case '/': sb.Append('/'); break;
case 'b': sb.Append('\b'); break;
case 'f': sb.Append('\f'); break;
case 'n': sb.Append('\n'); break;
case 'r': sb.Append('\r'); break;
case 't': sb.Append('\t'); break;
case 'u':
{
var remainingLength = _json.Length - index;
if (remainingLength < 4) break;
// 分析32位十六进制数字
var codePoint = ParseUnicode(_json[index], _json[index + 1], _json[index + 2], _json[index + 3]);
sb.Append((Char)codePoint);
index += 4;
}
break;
}
}
throw new Exception("已到达字符串结尾");
}
private String ParseString()
{
SkipToken(); // "
//_builder.Length = 0;
var sb = Pool.StringBuilder.Get();
var runIndex = -1;
while (index < _json.Length)
{
var c = _json[index++];
if (c == '"')
{
if (runIndex != -1)
{
if (sb.Length == 0) return _json.Substring(runIndex, index - runIndex - 1);
sb.Append(_json, runIndex, index - runIndex - 1);
}
return sb.Put(true);
}
if (c != '\\')
{
if (runIndex == -1) runIndex = index - 1;
continue;
}
if (index == _json.Length) break;
if (runIndex != -1)
{
sb.Append(_json, runIndex, index - runIndex - 1);
runIndex = -1;
}
switch (_json[index++])
{
case '"': sb.Append('"'); break;
case '\\': sb.Append('\\'); break;
case '/': sb.Append('/'); break;
case 'b': sb.Append('\b'); break;
case 'f': sb.Append('\f'); break;
case 'n': sb.Append('\n'); break;
case 'r': sb.Append('\r'); break;
case 't': sb.Append('\t'); break;
case 'u':
{
var remainingLength = _json.Length - index;
if (remainingLength < 4) break;
// 分析32位十六进制数字
var codePoint = ParseUnicode(_json[index], _json[index + 1], _json[index + 2], _json[index + 3]);
sb.Append((Char)codePoint);
index += 4;
}
break;
}
}
throw new Exception("已到达字符串结尾");
}
private UInt32 ParseSingleChar(Char c1, UInt32 multipliyer)
{
UInt32 p1 = 0;
if (c1 >= '0' && c1 <= '9')
p1 = (UInt32)(c1 - '0') * multipliyer;
else if (c1 >= 'A' && c1 <= 'F')
p1 = (UInt32)((c1 - 'A') + 10) * multipliyer;
else if (c1 >= 'a' && c1 <= 'f')
p1 = (UInt32)((c1 - 'a') + 10) * multipliyer;
return p1;
}
private UInt32 ParseUnicode(Char c1, Char c2, Char c3, Char c4)
{
var p1 = ParseSingleChar(c1, 0x1000);
var p2 = ParseSingleChar(c2, 0x100);
var p3 = ParseSingleChar(c3, 0x10);
var p4 = ParseSingleChar(c4, 1);
return p1 + p2 + p3 + p4;
}
private Int64 CreateLong(String s)
{
Int64 num = 0;
var neg = false;
foreach (var cc in s)
{
if (cc == '-')
neg = true;
else if (cc == '+')
neg = false;
else
{
num *= 10;
num += cc - '0';
}
}
return neg ? -num : num;
}
private Object ParseNumber()
{
SkipToken();
// 需要回滚1个位置，因为第一个数字也是Toekn，可能被跳过了
var startIndex = index - 1;
var dec = false;
do
{
if (index == _json.Length)
break;
var c = _json[index];
if ((c >= '0' && c <= '9') || c == '.' || c == '-' || c == '+' || c == 'e' || c == 'E')
{
if (c == '.' || c == 'e' || c == 'E')
dec = true;
if (++index == _json.Length) break;
continue;
}
break;
} while (true);
if (dec)
{
var s = _json.Substring(startIndex, index - startIndex);
return Double.Parse(s, NumberFormatInfo.InvariantInfo);
}
return CreateLong(out var num, _json, startIndex, index - startIndex);
}
private Token LookAhead()
{
if (_Ahead != Token.None) return _Ahead;
return _Ahead = NextTokenCore();
}
/// <summary>读取一个Token</summary>
private void SkipToken() => _Ahead = Token.None;
private Token NextToken()
{
var rs = _Ahead != Token.None ? _Ahead : NextTokenCore();
_Ahead = Token.None;
return rs;
}
private Token NextTokenCore()
{
Char ch;
// 跳过空白符
do
{
ch = _json[index];
if (ch > ' ') break;
if (ch != ' ' && ch != '\t' && ch != '\n' && ch != '\r') break;
} while (++index < _json.Length);
if (index == _json.Length) throw new Exception("已到达字符串结尾");
ch = _json[index];
index++;
switch (ch)
{
case '{':
return Token.Curly_Open;
case '}':
return Token.Curly_Close;
case '[':
return Token.Squared_Open;
case ']':
return Token.Squared_Close;
case ',':
return Token.Comma;
case '"':
return Token.String;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
case '-':
case '+':
case '.':
return Token.Number;
case ':':
return Token.Colon;
case 'f':
if (_json.Length - index >= 4 &&
_json[index + 0] == 'a' &&
_json[index + 1] == 'l' &&
_json[index + 2] == 's' &&
_json[index + 3] == 'e')
{
index += 4;
return Token.False;
}
break;
case 't':
if (_json.Length - index >= 3 &&
_json[index + 0] == 'r' &&
_json[index + 1] == 'u' &&
_json[index + 2] == 'e')
{
index += 3;
return Token.True;
}
break;
case 'n':
if (_json.Length - index >= 3 &&
_json[index + 0] == 'u' &&
_json[index + 1] == 'l' &&
_json[index + 2] == 'l')
{
index += 3;
return Token.Null;
}
break;
// 默认是没有双引号的key
default: index--; return Token.String;
}
throw new XException("无法在 {0} 找到Token", --index);
}
static Int64 CreateLong(out Int64 num, String s, Int32 index, Int32 count)
{
num = 0;
var neg = false;
for (var x = 0; x < count; x++, index++)
{
var cc = s[index];
if (cc == '-')
neg = true;
else if (cc == '+')
neg = false;
else
{
num *= 10;
num += cc - '0';
}
}
if (neg) num = -num;
return num;
}
}
}
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