MojoJson.cs

/*
 * Copyright (c) scott.cgi All Rights Reserved.
 * 
 * This source code belongs to project MojoJson, which is hosted on GitHub, and licensed under the MIT License.
 *
 * License: https://github.com/scottcgi/MojoJson/blob/master/LICENSE
 * GitHub : https://github.com/scottcgi/MojoJson
 *
 * Since  : 2017-9-6
 * Update : 2020-2-28
 * Author : scott.cgi
 * Version: 1.2.2
 */

using System.Collections.Generic;
using System.Text;
using System;

namespace MojoJson
{
    public static class Json 
    {
        private const  int  ObjectInitCapacity = 8;
        private const  int  ArrayInitCapacity  = 8;
        private static bool isEscapeString;


        #region Parse Json API


        /// <summary>
        /// Parse json string.
        /// </summary>
        public static JsonValue Parse(string json)
        {
            var data = new Data(json);
            return ParseValue(ref data);
        }

        /// <summary>
        /// Whether the string value need to be escaped ?
        /// </summary>
        public static void SetEscapeString(bool isEscapeString)
        {
            Json.isEscapeString = isEscapeString;
        }


        #endregion


        #region Parse Json 


        /// <summary>
        /// Parse the JsonValue.
        /// </summary>
        private static JsonValue ParseValue(ref Data data)
        {
            SkipWhiteSpace(ref data);

            switch (data.json[data.index])
            {
                case '{':
                    return ParseObject(ref data);

                case '[':
                    return ParseArray (ref data);

                case '"':
                    return ParseString(ref data);

                case '0':
                case '1':
                case '2':
                case '3':
                case '4':
                case '5':
                case '6':
                case '7':
                case '8':
                case '9':
                case '-':
                    return ParseNumber(ref data);

                case 'f':
                    if 
                    (
                        data.json[data.index + 1] == 'a' && 
                        data.json[data.index + 2] == 'l' &&
                        data.json[data.index + 3] == 's' &&
                        data.json[data.index + 4] == 'e'
                    )
                    {
                        data.index += 5;
                        return new JsonValue(JsonType.Bool, 0.0f);
                    }
                    break;

                case 't':
                    if 
                    (
                        data.json[data.index + 1] == 'r' && 
                        data.json[data.index + 2] == 'u' &&
                        data.json[data.index + 3] == 'e'
                    )
                    {
                        data.index += 4;
                        return new JsonValue(JsonType.Bool, 1.0f);
                    }
                    break;

                case 'n':
                    if 
                    (
                        data.json[data.index + 1] == 'u' && 
                        data.json[data.index + 2] == 'l' &&
                        data.json[data.index + 3] == 'l'
                    )
                    {
                        data.index += 4;
                        return new JsonValue(JsonType.Null, null);
                    }
                    break;
            }

            throw new Exception
            (
                string.Format
                (
                    "Json ParseValue error on char '{0}' index at '{1}' ", 
                    data.json[data.index], 
                    data.index
                )
            );
        }


        /// <summary>
        /// Parse JsonObject.
        /// </summary>
        private static JsonValue ParseObject(ref Data data)
        {
            var jsonObject = new Dictionary<string, JsonValue>(Json.ObjectInitCapacity);

            // skip '{'
            ++data.index;

            do
            {
                SkipWhiteSpace(ref data);

                if (data.json[data.index] == '}')
                {
                    break;
                }

                DebugTool.Assert
                (
                    data.json[data.index] == '"',  
                    "Json ParseObject error, char '{0}' should be '\"' ", 
                    data.json[data.index]
                );

                // get object key string
                var key = GetString(ref data);

                SkipWhiteSpace(ref data);

                DebugTool.Assert
                (
                    data.json[data.index] == ':',  
                    "Json ParseObject error, after key = {0}, char '{1}' should be ':' ", 
                    key,
                    data.json[data.index]
                );
            
                // skip ':'
                ++data.index;

                // set JsonObject key and value
                jsonObject.Add(key, ParseValue(ref data));

                SkipWhiteSpace(ref data);

                if (data.json[data.index] == ',')
                {
                    ++data.index;                   
                }
                else
                {
                    DebugTool.Assert
                    (
                        data.json[data.index] == '}',  
                        "Json ParseObject error, after key = {0}, char '{1}' should be '}' ",
                        key,
                        data.json[data.index]
                    );

                    break;
                }
            }
            while (true);

            // skip '}'
            ++data.index;

            return new JsonValue(JsonType.Object, jsonObject);
        }


        /// <summary>
        /// Parse JsonArray.
        /// </summary>
        private static JsonValue ParseArray(ref Data data)
        {
            var jsonArray = new List<JsonValue>(Json.ArrayInitCapacity);

            // skip '['
            ++data.index;

            do
            {
                SkipWhiteSpace(ref data);

                if (data.json[data.index] == ']')
                {
                    break;
                }

                // add JsonArray item 
                jsonArray.Add(ParseValue(ref data));

                SkipWhiteSpace(ref data);

                if (data.json[data.index] == ',')
                {
                    ++data.index;
                }
                else
                {
                    DebugTool.Assert
                    (
                        data.json[data.index] == ']',  
                        "Json ParseArray error, char '{0}' should be ']' ", 
                        data.json[data.index]
                    );
                    break;
                }
            }
            while (true);

            // skip ']'
            ++data.index;

            return new JsonValue(JsonType.Array, jsonArray);
        }


        /// <summary>
        /// Parses the JsonString.
        /// </summary>
        private static JsonValue ParseString(ref Data data)
        {
            string str;

            if (Json.isEscapeString == false)
            {
                str = GetString(ref data);
            }
            else
            {
                str = GetEscapedString(ref data);
            }

            return new JsonValue(JsonType.String, str);
        }


        /// <summary>
        /// Parses the JsonNumber.
        /// </summary>
        private static JsonValue ParseNumber(ref Data data)
        {
            var start = data.index;
                
            while (true)
            {
                switch (data.json[++data.index])
                {
                    case '0':
                    case '1':
                    case '2':
                    case '3':
                    case '4':
                    case '5':
                    case '6':
                    case '7':
                    case '8':
                    case '9':
                    case '-':
                    case '+':
                    case '.':
                    case 'e':
                    case 'E':
                        continue;
                }

                break;
            }

            var strNum = data.json.Substring(start, data.index - start);

            if (float.TryParse(strNum, out float num))
            {
                return new JsonValue(JsonType.Number, num);
            }

            throw new Exception(string.Format("Json ParseNumber error, cannot parse string [{0}]", strNum));
        }


        /// <summary>
        /// Skip the white space.
        /// </summary>
        private static void SkipWhiteSpace(ref Data data)
        {
            while (true)
            {
                switch (data.json[data.index])
                {
                    case ' ' :
                    case '\t':
                    case '\n':
                    case '\r':
                        ++data.index;
                        continue;
                }

                // index point to non-whitespace
                break;
            }
        }

        /// <summary>
        /// Get the original string value includes escape char.
        /// </summary>
        private static string GetString(ref Data data)
        {
            // skip '"'
            var start = ++data.index;

            while (true)
            {
                switch (data.json[data.index++])
                {
                    // check end '"'
                    case '"':
                        break;

                    case '\\':
                        // skip escaped quotes
                        // the escape char may be '\"'，which will break while
                        ++data.index;
                        continue;

                    default:
                        continue;
                }

                break;
            }

            // index after the string end '"' so -1
            return data.json.Substring(start, data.index - start - 1);
        }

        /// <summary>
        /// Get the escaped string value.
        /// </summary>
        private static string GetEscapedString(ref Data data)
        {
            // skip '"'
            var    start = ++data.index;
            string str;

            while (true)
            {
                switch (data.json[data.index++])
                {
                    // check string end '"' 
                    case '"':
                        if (data.sb.Length == 0)
                        {
                            // no escaped char just Substring
                            str = data.json.Substring(start, data.index - start - 1);
                        }
                        else
                        {
                            str = data.sb.Append(data.json, start, data.index - start - 1).ToString();
                            // clear for next string
                            data.sb.Length = 0;
                        }
                        break;

                    // check escaped char
                    case '\\':
                        {
                            var  escapedIndex = data.index;
                            char c;

                            switch (data.json[data.index++])
                            {
                                case '"':
                                    c = '"';
                                    break;

                                case '\\':
                                    c = '\\';
                                    break;

                                case '/':
                                    c = '/';
                                    break;

                                case '\'':
                                    c = '\'';
                                    break;

                                case 'b':
                                    c = '\b';
                                    break;

                                case 'f':
                                    c = '\f';
                                    break;

                                case 'n':
                                    c = '\n';
                                    break;

                                case 'r':
                                    c = '\r';
                                    break;

                                case 't':
                                    c = '\t';
                                    break;

                                case 'u':
                                    c = GetUnicodeCodePoint(ref data);
                                    break;

                                default:
                                    // not support just add in pre string
                                    continue;
                            }

                            // add pre string and escaped char
                            data.sb.Append(data.json, start, escapedIndex - start - 1).Append(c);

                            // update pre string start index
                            start = data.index;
                            continue;
                        }

                    default:
                        continue;
                }

                // index skipped the string end '"'
                break;
            }

            return str;
        }


        /// <summary>
        /// Get the unicode code point.
        /// </summary>
        private static char GetUnicodeCodePoint(ref Data data)
        {
            var index = data.index;

            for (var i = 0; i < 4; ++i)
            {
                char c = data.json[index + i];

                switch (c)
                {
                    case '0':
                        data.unicode[i] = 0;
                        break;

                    case '1':
                        data.unicode[i] = 1;
                        break;

                    case '2':
                        data.unicode[i] = 2;
                        break;

                    case '3':
                        data.unicode[i] = 3;
                        break;

                    case '4':
                        data.unicode[i] = 4;
                        break;

                    case '5':
                        data.unicode[i] = 5;
                        break;

                    case '6':
                        data.unicode[i] = 6;
                        break;

                    case '7':
                        data.unicode[i] = 7;
                        break;

                    case '8':
                        data.unicode[i] = 8;
                        break;

                    case '9':
                        data.unicode[i] = 9;
                        break;

                    case 'A':
                    case 'a':
                        data.unicode[i] = 10;
                        break;

                    case 'B':
                    case 'b':
                        data.unicode[i] = 11;
                        break;

                    case 'C':
                    case 'c':
                        data.unicode[i] = 12;
                        break;

                    case 'D':
                    case 'd':
                        data.unicode[i] = 13;
                        break;

                    case 'E':
                    case 'e':
                        data.unicode[i] = 14;
                        break;

                    case 'F':
                    case 'f':
                        data.unicode[i] = 15;
                        break;

                    default:
                        throw new Exception(string.Format("Json Unicode char '{0}' error", c));
                }
            }

            // skip code point
            data.index += 4;

            return (char) (
                              (data.unicode[0] << 12) +
                              (data.unicode[1] <<  8) +
                              (data.unicode[2] <<  4) +
                              (data.unicode[3]      )
                          );
        }


        #endregion


        private struct Data
        {
            public readonly string        json;
            public int                    index;
            public readonly StringBuilder sb;
            public readonly int[]         unicode; 

            public Data(string json)
            {
                this.json    = json;
                this.index   = 0;
                this.sb      = new StringBuilder();
                this.unicode = new int[4];
            }
        }
    }


    public enum JsonType
    {
        Object,
        Array,
        String,
        Number,
        Bool,
        Null,
    }


    public class JsonValue
    {
        public  readonly JsonType type;
        private readonly object   objectValue;
        private readonly float    numberValue;


        public JsonValue(JsonType type, object value)
        {
            this.type        = type;
            this.objectValue = value;
        }


        public JsonValue(JsonType type, float value)
        {
            this.type        = type;
            this.numberValue = value;
        }


        #region JsonObject API


        /// <summary>
        /// Use JsonValue as JsonObject.
        /// </summary>
        public Dictionary<string, JsonValue> AsObject()
        {
            DebugTool.Assert(this.type == JsonType.Object, "JsonValue type is not Object !");
            return this.objectValue as Dictionary<string, JsonValue>;
        }


        /// <summary>
        /// Use JsonValue as JsonObject and get JsonValue item by key.
        /// return null if not found key.
        /// </summary>
        public JsonValue AsObjectGet(string key)
        {
            DebugTool.Assert(this.type == JsonType.Object, "JsonValue type is not Object !");
            var dict = this.objectValue as Dictionary<string, JsonValue>;

            if (dict.TryGetValue(key, out JsonValue jsonValue))
            {
                return jsonValue;
            }

            return null;
        }


        /// <summary>
        /// Use JsonValue as JsonObject and get JsonObject item by key.
        /// return null if not found key.
        /// </summary>
        public Dictionary<string, JsonValue> AsObjectGetObject(string key)
        {
            var jsonValue = this.AsObjectGet(key);

            if (jsonValue != null)
            {
                return jsonValue.AsObject();
            }
            
            return null;               
        }


        /// <summary>
        /// Use JsonValue as JsonObject and get JsonArray item by key.
        /// return null if not found key.
        /// </summary>
        public List<JsonValue> AsObjectGetArray(string key)
        {
            var jsonValue = this.AsObjectGet(key);

            if (jsonValue != null)
            {
                return jsonValue.AsArray();
            }
           
            return null;               
        }


        /// <summary>
        /// Use JsonValue as JsonObject and get string item by key.
        /// return null if not found key.
        /// </summary>
        public string AsObjectGetString(string key)
        {
            var jsonValue = this.AsObjectGet(key);

            if (jsonValue != null)
            {
                return jsonValue.AsString();
            }
            
            return null;               
        }


        /// <summary>
        /// Use JsonValue as JsonObject and get float item by key.
        /// return defaultValue if not found key.
        /// </summary>
        public float AsObjectGetFloat(string key, float defaultValue)
        {
            var jsonValue = this.AsObjectGet(key);

            if (jsonValue != null)
            {
                return jsonValue.AsFloat();
            }
            
            return defaultValue;               
        }


        /// <summary>
        /// Use JsonValue as JsonObject and get float item by key.
        /// </summary>
        public float AsObjectGetFloat(string key)
        {
            return this.AsObjectGet(key).AsFloat();
        }


        /// <summary>
        /// Use JsonValue as JsonObject and get int item by key.
        /// return defaultValue if not found key.
        /// </summary>
        public int AsObjectGetInt(string key, int defaultValue)
        {
            var jsonValue = this.AsObjectGet(key);

            if (jsonValue != null)
            {
                return jsonValue.AsInt();
            }
           
            return defaultValue;               
        }


        /// <summary>
        /// Use JsonValue as JsonObject and get int item by key.
        /// </summary>
        public int AsObjectGetInt(string key)
        {
            return this.AsObjectGet(key).AsInt();
        }


        /// <summary>
        /// Use JsonValue as JsonObject and get bool item by key.
        /// return defaultValue if not found key.
        /// </summary>
        public bool AsObjectGetBool(string key, bool defaultValue)
        {
            var jsonValue = this.AsObjectGet(key);

            if (jsonValue != null)
            {
                return jsonValue.AsBool();
            }
           
            return defaultValue;               
        }


        /// <summary>
        /// Use JsonValue as JsonObject and get int item by key.
        /// </summary>
        public bool AsObjectGetBool(string key)
        {
            return this.AsObjectGet(key).AsBool();
        }


        /// <summary>
        /// Use JsonValue as JsonObject and check null item by key.
        /// </summary>
        public bool AsObjectGetIsNull(string key)
        {
            var jsonValue = this.AsObjectGet(key);

            if (jsonValue != null)
            {
                return jsonValue.IsNull();
            }
            
            return false;               
        }


        #endregion


        #region JsonArray API


        /// <summary>
        /// Use JsonValue as JsonArray.
        /// </summary>
        public List<JsonValue> AsArray()
        {
            DebugTool.Assert(this.type == JsonType.Array, "JsonValue type is not Array !");
            return this.objectValue as List<JsonValue>;
        }


        /// <summary>
        /// Use JsonValue as JsonArray and get JsonValue item by index.
        /// </summary>
        public JsonValue AsArrayGet(int index)
        {
            DebugTool.Assert(this.type == JsonType.Array, "JsonValue type is not Array !");
            return (this.objectValue as List<JsonValue>)[index];
        }


        /// <summary>
        /// Use JsonValue as JsonArray and get JsonObject item by index.
        /// </summary>
        public Dictionary<string, JsonValue> AsArrayGetObject(int index)
        {
            return this.AsArrayGet(index).AsObject();
        }


        /// <summary>
        /// Use JsonValue as JsonArray and get JsonArray item by index.
        /// </summary>
        public List<JsonValue> AsArrayGetArray(int index)
        {
            return this.AsArrayGet(index).AsArray();
        }


        /// <summary>
        /// Use JsonValue as JsonArray and get string item by index.
        /// </summary>
        public string AsArrayGetString(int index)
        {
            return this.AsArrayGet(index).AsString();
        }


        /// <summary>
        /// Use JsonValue as JsonArray and get float item by index.
        /// </summary>
        public float AsArrayGetFloat(int index)
        {
            return this.AsArrayGet(index).AsFloat();
        }


        /// <summary>
        /// Use JsonValue as JsonArray and get int item by index.
        /// </summary>
        public int AsArrayGetInt(int index)
        {
            return this.AsArrayGet(index).AsInt();
        }


        /// <summary>
        /// Use JsonValue as JsonArray and get bool item by index.
        /// </summary>
        public bool AsArrayGetBool(int index)
        {
            return this.AsArrayGet(index).AsBool();
        }


        /// <summary>
        /// Use JsonValue as JsonArray and check null item by index.
        /// </summary>
        public bool AsArrayGetIsNull(int index)
        {
            return this.AsArrayGet(index).IsNull();
        }


        #endregion


        #region Other Json value API


        /// <summary>
        /// Get JsonValue as string.
        /// </summary>
        public string AsString()
        {
            DebugTool.Assert(this.type == JsonType.String, "JsonValue type is not String !");
            return this.objectValue as string;
        }


        /// <summary>
        /// Get JsonValue as float.
        /// </summary>
        public float AsFloat()
        {
            DebugTool.Assert(this.type == JsonType.Number, "JsonValue type is not Number !");
            return this.numberValue;
        }


        /// <summary>
        /// Get JsonValue as int.
        /// </summary>
        public int AsInt()
        {
            DebugTool.Assert(this.type == JsonType.Number, "JsonValue type is not Number !");
            return (int) this.numberValue;
        }


        /// <summary>
        /// Get JsonValue as bool.
        /// </summary>
        public bool AsBool()
        {
            DebugTool.Assert(this.type == JsonType.Bool, "JsonValue type is not Bool !");
            return this.numberValue > 0.0f;
        }


        /// <summary>
        /// Whether JsonValue is null ？
        /// </summary>
        public bool IsNull()
        {
            return this.type == JsonType.Null;
        }


        #endregion
    }


    internal static class DebugTool
    {
        public static void Assert(bool condition, string msg, params object[] args)
        {
            if (condition == false)
            {
                throw new Exception(string.Format(msg, args));
            }
        }
    }
}