ReDOS at currency parsing fast-xml-parser

@@ -3,7 +3,7 @@ const {buildOptions,registerCommonValueParsers} = require("./ParserOptionsBuilde
 class OutputBuilder{
   constructor(options){
     this.options = buildOptions(options);
-      this.registeredParsers = registerCommonValueParsers();
+      this.registeredParsers = registerCommonValueParsers(this.options);
     }
     
     registerValueParser(name,parserInstance){//existing name will override the parser without warning

@@ -3,7 +3,7 @@ const {buildOptions,registerCommonValueParsers} = require("./ParserOptionsBuilde
 class OutputBuilder{
   constructor(options){
     this.options = buildOptions(options);
-      this.registeredParsers = registerCommonValueParsers();
+      this.registeredParsers = registerCommonValueParsers(this.options);
     }
     
     registerValueParser(name,parserInstance){//existing name will override the parser without warning

@@ -5,7 +5,7 @@ const {buildOptions,registerCommonValueParsers} = require("./ParserOptionsBuilde
 class OutputBuilder{
   constructor(builderOptions){
       this.options = buildOptions(builderOptions);
-      this.registeredParsers = registerCommonValueParsers();
+      this.registeredParsers = registerCommonValueParsers(this.options);
   }
 
   registerValueParser(name,parserInstance){//existing name will override the parser without warning

@@ -34,6 +34,9 @@ const defaultOptions={
       // "currency",
       // "date",
     ]
+  },
+  dataType:{
+
   }
 }
 
@@ -75,7 +78,7 @@ function copyProperties(target, source) {
   }
 }
 
-function registerCommonValueParsers(){
+function registerCommonValueParsers(options){
   return {
     "trim": new trimParser(),
     // "join": this.entityParser.parse,

@@ -1,20 +1,27 @@
-
+const defaultOptions = {
+    maxLength: 200,
+    // locale: "en-IN"
+}
 const localeMap = {
     "$":"en-US",
     "€":"de-DE",
     "£":"en-GB",
     "¥":"ja-JP",
     "₹":"en-IN",
 }
+const sign = "(?:-|\+)?";
+const digitsAndSeparator = "(?:\d+|\d{1,3}(?:,\d{3})+)";
+const decimalPart = "(?:\.\d{1,2})?";
+const symbol = "(?:\$|€|¥|₹)?";
 
 const currencyCheckRegex = /^\s*(?:-|\+)?(?:\d+|\d{1,3}(?:,\d{3})+)?(?:\.\d{1,2})?\s*(?:\$|€|¥|₹)?\s*$/u;
 
 class CurrencyParser{
     constructor(options){
-        this.options = options;
+        this.options = options || defaultOptions;
     }
     parse(val){
-        if (typeof val === 'string') {
+        if (typeof val === 'string' && val.length <= this.options.maxLength) {
             if(val.indexOf(",,") !== -1 && val.indexOf(".." !== -1)){
                 const match = val.match(currencyCheckRegex);
                 if(match){
@@ -28,4 +35,6 @@ class CurrencyParser{
         return val;
     }
 }
+CurrencyParser.defaultOptions = defaultOptions;
+
 module.exports = CurrencyParser;
\ No newline at end of file

@@ -1,5 +1,8 @@
 Note: If you find missing information about particular minor version, that version must have been changed without any functional change in this library.
 
+**4.3.5 / 2024-02-24**
+* code for v5 is added for experimental use
+
 **4.3.4 / 2024-01-10**
 * fix: Don't escape entities in CDATA sections (#633) (By [wackbyte](https://github.com/wackbyte))
 

@@ -0,0 +1,217 @@
+
+
+Example
+
+```js
+const options = {
+  preserveOrder: true,
+  removeNSPrefix: false, // remove NS from tag name or attribute name if true
+  stopNodes: [], //nested tags will not be parsed even for errors
+  htmlEntities: false,
+  tags:{
+    unpaired: [],
+    nameFor:{
+      cdata: false,
+      comment: false,
+      text: '#text'
+    },
+    separateTextProperty: false,
+    //"join" only if preserveOrder: true
+    valueParsers: ["trim","entities","join","boolean","number","currency","date"]
+  },
+  attributes: {
+      ignore: false,
+      booleanType:true,
+      entities: true,
+      //"groupBy": "att"
+  },
+  OutputBuilder: new JsObjOutputBuilder()
+};
+const parser = new XMLParser(options);
+let result = parser.parse(xmlData, true);
+```
+
+- You can build your own Output Builder. FXP provides 3 builders
+  - JsObjOutputBuilder
+  - JsArrBuilder
+  - JsMinArrBuilder
+- You can control the sequence of value parsing for a tag or attribute
+- You can pass a string or bytes array as input.
+
+### Value Parser
+You can change the sequence of value parsers or remove one or provide your own parser to control the parsing.
+
+### Output builders
+You can use provided output builds or your own output builder.
+
+JsObjOutputBuilder
+```js
+{
+    "soap:Envelope": {
+        "@_xmlns:soap": "http://schemas.xmlsoap.org/soap/envelope/",
+        "soap:Body": {
+            "rpt:loadReportFileResponseElem": {
+                "@_xmlns:s": "http://bus.x.com/common/support/v1",
+                "@_xmlns:rpt": "http://bus.x.com/service/statement/v1",
+                "s:code": 0,
+                "s:responseTime": 2588,
+                "s:responseDbTime": 1893,
+                "s:requestId": "6b408fd09eb211e7a0807e34820340ec",
+                "s:route": "172.16.x.x:9192",
+                "rpt:result": {
+                    "rpt:file": "<soap:Envelope xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">\n    <soap:Body>\n        <rpt:loadReportFileResponseElem\n                xmlns:s=\"http://bus.x.com/common/support/v1\"\n                xmlns:rpt=\"http://bus.x.com/service/statement/v1\">\n            <s:code>0</s:code>\n            <s:responseTime>2588</s:responseTime>\n            <s:responseDbTime>1893</s:responseDbTime>\n            <s:requestId>6b408fd09eb211e7a0807e34820340ec</s:requestId>\n            <s:route>172.16.x.x:9192</s:route>\n            <rpt:result>\n <rpt:file></rpt:file>\n            </rpt:result>\n        </rpt:loadReportFileResponseElem>\n    </soap:Body>\n</soap:Envelope>"
+                }
+            }
+        }
+    }
+}
+```
+
+JsArrBuilder
+```js
+{
+    "tagname": "soap:Envelope",
+    "child": [
+        {
+            "tagname": "soap:Body",
+            "child": [
+                {
+                    "tagname": "rpt:loadReportFileResponseElem",
+                    "child": [
+                        {
+                            "tagname": "s:code",
+                            "child": [
+                                {
+                                    "#text": 0
+                                }
+                            ]
+                        },
+                        {
+                            "tagname": "s:responseTime",
+                            "child": [
+                                {
+                                    "#text": 2588
+                                }
+                            ]
+                        },
+                        {
+                            "tagname": "s:responseDbTime",
+                            "child": [
+                                {
+                                    "#text": 1893
+                                }
+                            ]
+                        },
+                        {
+                            "tagname": "s:requestId",
+                            "child": [
+                                {
+                                    "#text": "6b408fd09eb211e7a0807e34820340ec"
+                                }
+                            ]
+                        },
+                        {
+                            "tagname": "s:route",
+                            "child": [
+                                {
+                                    "#text": "172.16.x.x:9192"
+                                }
+                            ]
+                        },
+                        {
+                            "tagname": "rpt:result",
+                            "child": [
+                                {
+                                    "tagname": "rpt:file",
+                                    "child": [
+                                        {
+                                            "#text": "<soap:Envelope xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">\n    <soap:Body>\n        <rpt:loadReportFileResponseElem\n                xmlns:s=\"http://bus.x.com/common/support/v1\"\n                xmlns:rpt=\"http://bus.x.com/service/statement/v1\">\n            <s:code>0</s:code>\n            <s:responseTime>2588</s:responseTime>\n            <s:responseDbTime>1893</s:responseDbTime>\n            <s:requestId>6b408fd09eb211e7a0807e34820340ec</s:requestId>\n            <s:route>172.16.x.x:9192</s:route>\n            <rpt:result>\n <rpt:file></rpt:file>\n            </rpt:result>\n        </rpt:loadReportFileResponseElem>\n    </soap:Body>\n</soap:Envelope>"
+                                        }
+                                    ]
+                                }
+                            ]
+                        }
+                    ],
+                    ":@": {
+                        "@_xmlns:s": "http://bus.x.com/common/support/v1",
+                        "@_xmlns:rpt": "http://bus.x.com/service/statement/v1"
+                    }
+                }
+            ]
+        }
+    ],
+    ":@": {
+        "@_xmlns:soap": "http://schemas.xmlsoap.org/soap/envelope/"
+    }
+}
+```
+
+JsMinArrBuilder
+```js
+{
+    "soap:Envelope": [
+        {
+            "soap:Body": [
+                {
+                    "rpt:loadReportFileResponseElem": [
+                        {
+                            "s:code": [
+                                {
+                                    "#text": 0
+                                }
+                            ]
+                        },
+                        {
+                            "s:responseTime": [
+                                {
+                                    "#text": 2588
+                                }
+                            ]
+                        },
+                        {
+                            "s:responseDbTime": [
+                                {
+                                    "#text": 1893
+                                }
+                            ]
+                        },
+                        {
+                            "s:requestId": [
+                                {
+                                    "#text": "6b408fd09eb211e7a0807e34820340ec"
+                                }
+                            ]
+                        },
+                        {
+                            "s:route": [
+                                {
+                                    "#text": "172.16.x.x:9192"
+                                }
+                            ]
+                        },
+                        {
+                            "rpt:result": [
+                                {
+                                    "rpt:file": [
+                                        {
+                                            "#text": "<soap:Envelope xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">\n    <soap:Body>\n        <rpt:loadReportFileResponseElem\n                xmlns:s=\"http://bus.x.com/common/support/v1\"\n                xmlns:rpt=\"http://bus.x.com/service/statement/v1\">\n            <s:code>0</s:code>\n            <s:responseTime>2588</s:responseTime>\n            <s:responseDbTime>1893</s:responseDbTime>\n            <s:requestId>6b408fd09eb211e7a0807e34820340ec</s:requestId>\n            <s:route>172.16.x.x:9192</s:route>\n            <rpt:result>\n <rpt:file></rpt:file>\n            </rpt:result>\n        </rpt:loadReportFileResponseElem>\n    </soap:Body>\n</soap:Envelope>"
+                                        }
+                                    ]
+                                }
+                            ]
+                        }
+                    ],
+                    ":@": {
+                        "@_xmlns:s": "http://bus.x.com/common/support/v1",
+                        "@_xmlns:rpt": "http://bus.x.com/service/statement/v1"
+                    }
+                }
+            ]
+        }
+    ],
+    ":@": {
+        "@_xmlns:soap": "http://schemas.xmlsoap.org/soap/envelope/"
+    }
+}
+```
+

@@ -1,6 +1,6 @@
 {
   "name": "fast-xml-parser",
-  "version": "4.3.4",
+  "version": "4.3.5",
   "description": "Validate XML, Parse XML, Build XML without C/C++ based libraries",
   "main": "./src/fxp.js",
   "scripts": {

@@ -1,12 +1,12 @@
 {
   "name": "fast-xml-parser",
-  "version": "4.3.4",
+  "version": "4.3.5",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "fast-xml-parser",
-      "version": "4.3.4",
+      "version": "4.3.5",
       "funding": [
         {
           "type": "paypal",

@@ -11,7 +11,8 @@
 
 Validate XML, Parse XML to JS Object, or Build XML from JS Object without C/C++ based libraries and no callback.
 
-<font size="6">I need a Career advice. I've posted the query on my <a href="github.com/amitguptagwl">profile</a>. Your support would be appreciable.</font>
+> XML Parser v5 is added for experimental use
+> https://solothought.com
 
 Sponsor this project 👉 
 <a href="https://github.com/sponsors/NaturalIntelligence"> 
@@ -91,6 +92,11 @@ If you want to be an anonymous user of this application and don't want to be hig
 * Supports parsing of PI (Processing Instruction) tags with XML declaration tags
 * And many more other features.
 
+## v5
+I developed v5 in Apr 2023. And I didn't get the chance to complete all the features. I've ensured that new features don't impact performance. With v5, you have more control on parsing output. Check [docs](./docs/v5) for syntax help and basic understanding.
+
+Please leave a comment in discussion forum for your suggestions and if you really need v5.
+
 ## How to use
 
 To use as package dependency
@@ -174,19 +180,6 @@ Check lib folder for different browser bundles
 
 [![](static/img/ni_ads_ads.gif)](https://github.com/NaturalIntelligence/ads/)
 
-## Our other projects and research you must try
-
-* **[BigBit standard](https://github.com/amitguptagwl/bigbit)** : 
-  * Single text encoding to replace UTF-8, UTF-16, UTF-32 and more with less memory.
-  * Single Numeric datatype alternative of integer, float, double, long, decimal and more without precision loss.
-* **[Cytorus](https://github.com/NaturalIntelligence/cytorus)**:  Be specific and flexible while running E2E tests.
-  * Run tests only for a particular User Story
-  * Run tests for a route or from a route
-  * Customizable reporting
-  * Central dashboard for better monitoring
-  * Options to integrate E2E tests with Jira, Github etc using Central dashboard `Tian`.
-* **[Stubmatic](https://github.com/NaturalIntelligence/Stubmatic)** : Create fake webservices, DynamoDB or S3 servers, Manage fake/mock stub data, Or fake any HTTP(s) call.
-
 
 ## Supporters
 ### Contributors

@@ -0,0 +1,32 @@
+const XMLParser = require("../../src/v5/XMLParser");
+const JsObjOutputBuilder = require("../../src/v5/OutputBuilders/JsObjBuilder");
+const JsArrBuilder = require("../../src/v5/OutputBuilders/JsArrBuilder");
+const JsMinArrBuilder = require("../../src/v5/OutputBuilders/JsMinArrBuilder");
+
+const fs = require("fs");
+const path = require("path");
+const fileNamePath = path.join(__dirname, "../assets/ptest.xml");//with CDATA
+// const fileNamePath = path.join(__dirname, "../assets/ptest_with_prolog.xml");//with CDATA
+// const fileNamePath = path.join(__dirname, "../assets/sample.xml");//1.5k
+// const fileNamePath = path.join(__dirname, "../assets/midsize.xml");//13m
+// const fileNamePath = path.join(__dirname, "../assets/large.xml");//98m
+const xmlData = fs.readFileSync(fileNamePath).toString();
+
+describe("XMLParser Entities", function() {
+
+  it("should parse", function() {
+      
+      const options = {
+          attributes: {
+              ignore: false,
+              booleanType:true
+          },
+          OutputBuilder: new JsMinArrBuilder()
+      };
+      const parser = new XMLParser(options);
+      let result = parser.parse(xmlData);
+
+      console.log(JSON.stringify(result,null,4));
+    //   expect(result).toEqual(expected);
+  });
+});
\ No newline at end of file

@@ -0,0 +1,16 @@
+modules.export = {
+  "<" : "<", //tag start
+  ">" : ">", //tag end
+  "/" : "/", //close tag
+  "!" : "!", //comment or docttype
+  "!--" : "!--", //comment
+  "-->" : "-->", //comment end
+  "?" : "?", //pi
+  "?>" : "?>", //pi end
+  "?xml" : "?xml", //pi end
+  "![" : "![", //cdata
+  "]]>" : "]]>", //cdata end
+  "[" : "[",
+  "-" : "-",
+  "D" : "D",
+}
\ No newline at end of file

@@ -0,0 +1,105 @@
+const ampEntity = { regex: /&(amp|#38|#x26);/g, val : "&"};
+const htmlEntities = {
+    "space": { regex: /&(nbsp|#160);/g, val: " " },
+    // "lt" : { regex: /&(lt|#60);/g, val: "<" },
+    // "gt" : { regex: /&(gt|#62);/g, val: ">" },
+    // "amp" : { regex: /&(amp|#38);/g, val: "&" },
+    // "quot" : { regex: /&(quot|#34);/g, val: "\"" },
+    // "apos" : { regex: /&(apos|#39);/g, val: "'" },
+    "cent" : { regex: /&(cent|#162);/g, val: "¢" },
+    "pound" : { regex: /&(pound|#163);/g, val: "£" },
+    "yen" : { regex: /&(yen|#165);/g, val: "¥" },
+    "euro" : { regex: /&(euro|#8364);/g, val: "€" },
+    "copyright" : { regex: /&(copy|#169);/g, val: "©" },
+    "reg" : { regex: /&(reg|#174);/g, val: "®" },
+    "inr" : { regex: /&(inr|#8377);/g, val: "₹" },
+};
+
+class EntitiesParser{
+    constructor(replaceHtmlEntities) {
+      this.replaceHtmlEntities = replaceHtmlEntities;
+      this.docTypeEntities = {};
+      this.lastEntities = {
+        "apos" : { regex: /&(apos|#39|#x27);/g, val : "'"},
+        "gt" : { regex: /&(gt|#62|#x3E);/g, val : ">"},
+        "lt" : { regex: /&(lt|#60|#x3C);/g, val : "<"},
+        "quot" : { regex: /&(quot|#34|#x22);/g, val : "\""},
+      };
+    }
+
+    addExternalEntities(externalEntities){
+        const entKeys = Object.keys(externalEntities);
+        for (let i = 0; i < entKeys.length; i++) {
+          const ent = entKeys[i];
+          this.addExternalEntity(ent,externalEntities[ent])
+        }
+    }
+    addExternalEntity(key,val){
+      validateEntityName(key);
+      if(val.indexOf("&") !== -1) {
+        reportWarning(`Entity ${key} is not added as '&' is found in value;`)
+        return;
+      }else{
+        this.lastEntities[ent] = {
+          regex: new RegExp("&"+key+";","g"),
+          val : val
+        }
+      }
+    }
+
+    addDocTypeEntities(entities){
+        const entKeys = Object.keys(entities);
+        for (let i = 0; i < entKeys.length; i++) {
+          const ent = entKeys[i];
+          this.docTypeEntities[ent] = {
+             regex: new RegExp("&"+ent+";","g"),
+             val : entities[ent]
+          }
+        }
+    }
+
+    parse(val){
+        return this.replaceEntitiesValue(val)
+    }
+
+    /**
+     * 1. Replace DOCTYPE entities 
+     * 2. Replace external entities 
+     * 3. Replace HTML entities if asked
+     * @param {string} val 
+     */
+    replaceEntitiesValue(val){
+        if(typeof val === "string" && val.length > 0){
+            for(let entityName in this.docTypeEntities){
+                const entity = this.docTypeEntities[entityName];
+                val = val.replace( entity.regx, entity.val);
+              }
+              for(let entityName in this.lastEntities){
+                const entity = this.lastEntities[entityName];
+                val = val.replace( entity.regex, entity.val);
+              }
+              if(this.replaceHtmlEntities){
+                for(let entityName in htmlEntities){
+                  const entity = htmlEntities[entityName];
+                  val = val.replace( entity.regex, entity.val);
+                }
+              }
+            val = val.replace( ampEntity.regex, ampEntity.val);
+        }
+        return val;
+    }
+};
+
+//an entity name should not contains special characters that may be used in regex
+//Eg !?\\\/[]$%{}^&*()<>
+const specialChar = "!?\\\/[]$%{}^&*()<>|+";
+
+function validateEntityName(name){
+    for (let i = 0; i < specialChar.length; i++) {
+        const ch = specialChar[i];
+        if(name.indexOf(ch) !== -1) throw new Error(`Invalid character ${ch} in entity name`);
+    }
+    return name;
+}
+
+module.exports = EntitiesParser;
\ No newline at end of file

@@ -0,0 +1,118 @@
+const Constants = {
+  space: 32,
+  tab: 9
+}
+class BufferSource{
+  constructor(bytesArr){
+    this.line = 1;
+    this.cols = 0;
+    this.buffer = bytesArr;
+    this.startIndex = 0;
+  }
+
+
+
+  readCh() {
+    return String.fromCharCode(this.buffer[this.startIndex++]);
+  }
+
+  readChAt(index) {
+    return String.fromCharCode(this.buffer[this.startIndex+index]);
+  }
+
+  readStr(n,from){
+    if(typeof from === "undefined") from = this.startIndex;
+    return this.buffer.slice(from, from + n).toString();
+  }
+
+  readUpto(stopStr) {
+    const inputLength = this.buffer.length;
+    const stopLength = stopStr.length;
+    const stopBuffer = Buffer.from(stopStr);
+
+    for (let i = this.startIndex; i < inputLength; i++) {
+        let match = true;
+        for (let j = 0; j < stopLength; j++) {
+            if (this.buffer[i + j] !== stopBuffer[j]) {
+                match = false;
+                break;
+            }
+        }
+
+        if (match) {
+            const result = this.buffer.slice(this.startIndex, i).toString();
+            this.startIndex = i + stopLength;
+            return result;
+        }
+    }
+
+    throw new Error(`Unexpected end of source. Reading '${stopStr}'`);
+}
+
+readUptoCloseTag(stopStr) { //stopStr: "</tagname"
+    const inputLength = this.buffer.length;
+    const stopLength = stopStr.length;
+    const stopBuffer = Buffer.from(stopStr);
+    let stopIndex = 0;
+    //0: non-matching, 1: matching stop string, 2: matching closing
+    let match = 0;
+
+    for (let i = this.startIndex; i < inputLength; i++) {
+        if(match === 1){//initial part matched
+            if(stopIndex === 0) stopIndex = i;
+            if(this.buffer[i] === Constants.space || this.buffer[i] === Constants.tab) continue;
+            else if(this.buffer[i] === '>'){ //TODO: if it should be equivalent ASCII
+                match = 2;
+                //tag boundary found
+                // this.startIndex
+            }
+        }else{
+            match = 1;
+            for (let j = 0; j < stopLength; j++) {
+                if (this.buffer[i + j] !== stopBuffer[j]) {
+                    match = 0;
+                    break;
+                }
+            }
+        }
+        if (match === 2) {//matched closing part
+            const result = this.buffer.slice(this.startIndex, stopIndex - 1 ).toString();
+            this.startIndex = i + 1;
+            return result;
+        }
+    }
+
+    throw new Error(`Unexpected end of source. Reading '${stopStr}'`);
+}
+
+  readFromBuffer(n, shouldUpdate) {
+    let ch;
+    if (n === 1) {
+      ch = this.buffer[this.startIndex];
+      if (ch === 10) {
+        this.line++;
+        this.cols = 1;
+      } else {
+        this.cols++;
+      }
+      ch = String.fromCharCode(ch);
+    } else {
+      this.cols += n;
+      ch = this.buffer.slice(this.startIndex, this.startIndex + n).toString();
+    }
+    if (shouldUpdate) this.updateBuffer(n);
+    return ch;
+  }
+
+  updateBufferBoundary(n = 1) { //n: number of characters read
+    this.startIndex += n;
+  }
+
+  canRead(n){
+    n = n || this.startIndex;
+    return this.buffer.length - n + 1 > 0;
+  }
+  
+}
+
+module.exports = BufferSource;
\ No newline at end of file

@@ -0,0 +1,123 @@
+const whiteSpaces = [" ", "\n", "\t"];
+
+
+class StringSource{
+  constructor(str){
+    this.line = 1;
+    this.cols = 0;
+    this.buffer = str;
+    //a boundary pointer to indicate where from the buffer dat should be read
+    // data before this pointer can be deleted to free the memory
+    this.startIndex = 0;
+  }
+
+  readCh() {
+    return this.buffer[this.startIndex++];
+  }
+
+  readChAt(index) {
+    return this.buffer[this.startIndex+index];
+  }
+
+  readStr(n,from){
+    if(typeof from === "undefined") from = this.startIndex;
+    return this.buffer.substring(from, from + n);
+  }
+
+  readUpto(stopStr) {
+    const inputLength = this.buffer.length;
+    const stopLength = stopStr.length;
+
+    for (let i = this.startIndex; i < inputLength; i++) {
+      let match = true;
+      for (let j = 0; j < stopLength; j++) {
+        if (this.buffer[i + j] !== stopStr[j]) {
+          match = false;
+          break;
+        }
+      }
+
+      if (match) {
+        const result = this.buffer.substring(this.startIndex, i);
+        this.startIndex = i + stopLength;
+        return result;
+      }
+    }
+
+    throw new Error(`Unexpected end of source. Reading '${stopStr}'`);
+  }
+
+  readUptoCloseTag(stopStr) { //stopStr: "</tagname"
+    const inputLength = this.buffer.length;
+    const stopLength = stopStr.length;
+    let stopIndex = 0;
+    //0: non-matching, 1: matching stop string, 2: matching closing
+    let match = 0;
+
+    for (let i = this.startIndex; i < inputLength; i++) {
+      if(match === 1){//initial part matched
+        if(stopIndex === 0) stopIndex = i;
+        if(this.buffer[i] === ' ' || this.buffer[i] === '\t') continue;
+        else if(this.buffer[i] === '>'){
+          match = 2;
+          //tag boundary found
+          // this.startIndex
+        }
+      }else{
+        match = 1;
+        for (let j = 0; j < stopLength; j++) {
+          if (this.buffer[i + j] !== stopStr[j]) {
+            match = 0;
+            break;
+          }
+        }
+      }
+      if (match === 2) {//matched closing part
+        const result = this.buffer.substring(this.startIndex, stopIndex - 1 );
+        this.startIndex = i + 1;
+        return result;
+      }
+    }
+
+    throw new Error(`Unexpected end of source. Reading '${stopStr}'`);
+  }
+
+  readFromBuffer(n, updateIndex){
+    let ch;
+    if(n===1){
+      ch = this.buffer[this.startIndex];
+      // if(ch === "\n") {
+      //   this.line++;
+      //   this.cols = 1;
+      // }else{
+      //   this.cols++;
+      // }
+    }else{
+      ch = this.buffer.substring(this.startIndex, this.startIndex + n);
+      // if("".indexOf("\n") !== -1){
+      //   //TODO: handle the scenario when there are multiple lines
+      //   //TODO: col should be set to number of chars after last '\n'
+      //   // this.cols = 1;
+      // }else{
+      //   this.cols += n;
+
+      // }
+    }
+    if(updateIndex) this.updateBufferBoundary(n);
+    return ch;
+  }
+
+  //TODO: rename to updateBufferReadIndex
+  
+  updateBufferBoundary(n = 1) { //n: number of characters read
+    this.startIndex += n;
+  }
+
+  canRead(n){
+    n = n || this.startIndex;
+    return this.buffer.length - n + 1 > 0;
+  }
+  
+}
+
+module.exports = StringSource;
\ No newline at end of file

@@ -0,0 +1,73 @@
+
+const JsArrBuilder = require("./OutputBuilders/JsArrBuilder");
+
+const defaultOptions = {
+  preserveOrder: false,
+  removeNSPrefix: false, // remove NS from tag name or attribute name if true
+  //ignoreRootElement : false,
+  stopNodes: [], //nested tags will not be parsed even for errors
+  // isArray: () => false, //User will set it
+  htmlEntities: false,
+  // skipEmptyListItem: false
+  tags:{
+    unpaired: [],
+    nameFor:{
+      cdata: false,
+      comment: false,
+      text: '#text'
+    },
+    separateTextProperty: false,
+    valueParsers: []
+  },
+  attributes:{
+    ignore: false,
+    booleanType: true,
+    entities: true
+  },
+
+  // select: ["img[src]"],
+  // stop: ["anim", "[ads]"]
+  only: [], // rest tags will be skipped. It will result in flat array
+  hierarchy: false, //will be used when a particular tag is set to be parsed.
+  skip: [], // will be skipped from parse result. on('skip') will be triggered
+
+  select: [], // on('select', tag => tag ) will be called if match
+  stop: [], //given tagPath will not be parsed. innerXML will be set as string value
+  OutputBuilder: new JsArrBuilder(),
+};
+   
+const buildOptions = function(options) {
+  const finalOptions = { ... defaultOptions};
+  finalOptions.tags.valueParsers.push("trim");
+  finalOptions.tags.valueParsers.push("entities");
+  if(!this.preserveOrder)
+    finalOptions.tags.valueParsers.push("join");
+  finalOptions.tags.valueParsers.push("boolean");
+  finalOptions.tags.valueParsers.push("number");
+  finalOptions.tags.valueParsers.push("currency");
+  finalOptions.tags.valueParsers.push("date");
+  copyProperties(finalOptions,options)
+  return  finalOptions;
+};
+
+function copyProperties(target, source) {
+  for (let key in source) {
+    if (source.hasOwnProperty(key)) {
+      if (key === 'OutputBuilder') {
+        target[key] = source[key];
+      }else if (typeof source[key] === 'object' && !Array.isArray(source[key])) {
+        // Recursively copy nested properties
+        if (typeof target[key] === 'undefined') {
+          target[key] = {};
+        }
+        copyProperties(target[key], source[key]);
+      } else {
+        // Copy non-nested properties
+        target[key] = source[key];
+      }
+    }
+  }
+}
+
+exports.buildOptions = buildOptions;
+exports.defaultOptions = defaultOptions;
\ No newline at end of file

@@ -0,0 +1,69 @@
+class BaseOutputBuilder{
+  constructor(){
+    // this.attributes = {};
+  }
+
+  addAttribute(name, value){
+    if(this.options.onAttribute){
+      //TODO: better to pass tag path
+      const v = this.options.onAttribute(name, value, this.tagName);
+      if(!v) this.attributes[v.name] = v.value;
+    }else{
+      name = this.options.attributes.prefix + name + this.options.attributes.suffix;
+      this.attributes[name] = this.parseValue(value, this.options.attributes.valueParsers);
+    }
+  }
+
+  /**
+   * parse value by chain of parsers
+   * @param {string} val 
+   * @returns {any} parsed value if matching parser found
+   */
+    parseValue = function(val, valParsers){
+      for (let i = 0; i < valParsers.length; i++) {
+        let valParser = this.registeredParsers[valParsers[i]];
+        if(valParser){
+          val = valParser.parse(val);
+          // if(!valParser.chainable) break;
+        }
+      }
+      return val;
+    }
+
+  /**
+   * To add a nested empty tag.
+   * @param {string} key 
+   * @param {any} val 
+   */
+  _addChild(key, val){}
+
+  /**
+   * skip the comment if property is not set
+   */
+  addComment(text){
+    if(this.options.nameFor.comment)
+      this._addChild(this.options.nameFor.comment, text);
+  }
+
+  //store CDATA separately if property is set
+  //otherwise add to tag's value
+  addCdata(text){
+    if (this.options.nameFor.cdata) {
+      this._addChild(this.options.nameFor.cdata, text);
+    } else {
+      this.addRawValue(text || "");
+    }
+  }
+
+  addRawValue = text => this.addValue(text);
+
+  addDeclaration(){
+    if(!this.options.declaration){
+    }else{
+      this.addPi("?xml");
+    }
+    this.attributes = {}
+  }
+}
+
+module.exports = BaseOutputBuilder;
\ No newline at end of file

@@ -0,0 +1,102 @@
+const {buildOptions,registerCommonValueParsers} = require("./ParserOptionsBuilder");
+
+class OutputBuilder{
+  constructor(options){
+    this.options = buildOptions(options);
+      this.registeredParsers = registerCommonValueParsers();
+    }
+    
+    registerValueParser(name,parserInstance){//existing name will override the parser without warning
+      this.registeredParsers[name] = parserInstance;
+    }
+
+  getInstance(){
+    return new JsArrBuilder(this.options, this.registeredParsers);
+  }
+}
+
+const rootName = '!js_arr';
+const BaseOutputBuilder = require("./BaseOutputBuilder");
+
+class JsArrBuilder extends BaseOutputBuilder{
+
+  constructor(options,registeredParsers) {
+    super();
+    this.tagsStack = [];
+    this.options = options;
+    this.registeredParsers = registeredParsers;
+
+    this.root = new Node(rootName);
+    this.currentNode = this.root;
+    this.attributes = {};
+  }
+
+  addTag(tag){
+    //when a new tag is added, it should be added as child of current node
+    //TODO: shift this check to the parser
+    if(tag.name === "__proto__") tag.name = "#__proto__";
+
+    this.tagsStack.push(this.currentNode);
+    this.currentNode = new Node(tag.name, this.attributes);
+    this.attributes = {};
+  }
+
+  /**
+   * Check if the node should be added by checking user's preference
+   * @param {Node} node 
+   * @returns boolean: true if the node should not be added
+   */
+  closeTag(){
+    const node = this.currentNode;
+    this.currentNode = this.tagsStack.pop(); //set parent node in scope
+    if(this.options.onClose !== undefined){
+      //TODO TagPathMatcher 
+      const resultTag = this.options.onClose(node, 
+        new TagPathMatcher(this.tagsStack,node));
+
+      if(resultTag) return;
+    }
+    this.currentNode.child.push(node);  //to parent node
+  }
+
+  //Called by parent class methods
+  _addChild(key, val){
+    // if(key === "__proto__") tagName = "#__proto__";
+    this.currentNode.child.push( {[key]: val });
+    // this.currentNode.leafType = false;
+  }
+
+  /**
+   * Add text value child node 
+   * @param {string} text 
+   */
+  addValue(text){
+    this.currentNode.child.push( {[this.options.nameFor.text]: this.parseValue(text, this.options.tags.valueParsers) });
+  }
+
+  addPi(name){
+    //TODO: set pi flag
+    if(!this.options.ignorePiTags){
+      const node = new Node(name, this.attributes);
+      this.currentNode[":@"] = this.attributes;
+      this.currentNode.child.push(node);
+    }
+    this.attributes = {};
+  }
+  getOutput(){
+    return this.root.child[0];
+  }
+}
+
+
+
+class Node{
+  constructor(tagname, attributes){
+    this.tagname = tagname;
+    this.child = []; //nested tags, text, cdata, comments
+    if(attributes && Object.keys(attributes).length > 0)
+      this[":@"] = attributes;
+  }
+}
+
+module.exports = OutputBuilder;
\ No newline at end of file

@@ -0,0 +1,101 @@
+const {buildOptions,registerCommonValueParsers} = require("./ParserOptionsBuilder");
+
+class OutputBuilder{
+  constructor(options){
+    this.options = buildOptions(options);
+      this.registeredParsers = registerCommonValueParsers();
+    }
+    
+    registerValueParser(name,parserInstance){//existing name will override the parser without warning
+      this.registeredParsers[name] = parserInstance;
+    }
+
+  getInstance(){
+    return new JsMinArrBuilder(this.options, this.registeredParsers);
+  }
+}
+
+const BaseOutputBuilder = require("./BaseOutputBuilder");
+const rootName = '^';
+
+class JsMinArrBuilder extends BaseOutputBuilder{
+
+  constructor(options,registeredParsers) {
+    super();
+    this.tagsStack = [];
+    this.options = options;
+    this.registeredParsers = registeredParsers;
+
+    this.root = {[rootName]: []};
+    this.currentNode = this.root;
+    this.currentNodeTagName = rootName;
+    this.attributes = {};
+  }
+
+  addTag(tag){
+    //when a new tag is added, it should be added as child of current node
+    //TODO: shift this check to the parser
+    if(tag.name === "__proto__") tag.name = "#__proto__";
+
+    this.tagsStack.push([this.currentNodeTagName,this.currentNode]); //this.currentNode is parent node here
+    this.currentNodeTagName = tag.name;
+    this.currentNode = { [tag.name]:[]}
+    if(Object.keys(this.attributes).length > 0){
+      this.currentNode[":@"] = this.attributes;
+      this.attributes = {};
+    }
+  }
+
+  /**
+   * Check if the node should be added by checking user's preference
+   * @param {Node} node 
+   * @returns boolean: true if the node should not be added
+   */
+  closeTag(){
+    const node = this.currentNode;
+    const nodeName = this.currentNodeTagName;
+    const arr = this.tagsStack.pop(); //set parent node in scope
+    this.currentNodeTagName = arr[0];
+    this.currentNode = arr[1];
+
+    if(this.options.onClose !== undefined){
+      //TODO TagPathMatcher 
+      const resultTag = this.options.onClose(node, 
+        new TagPathMatcher(this.tagsStack,node));
+
+      if(resultTag) return;
+    }
+    this.currentNode[this.currentNodeTagName].push(node);  //to parent node
+  }
+
+  //Called by parent class methods
+  _addChild(key, val){
+    // if(key === "__proto__") tagName = "#__proto__";
+    this.currentNode.push( {[key]: val });
+    // this.currentNode.leafType = false;
+  }
+
+  /**
+   * Add text value child node 
+   * @param {string} text 
+   */
+  addValue(text){
+    this.currentNode[this.currentNodeTagName].push( {[this.options.nameFor.text]: this.parseValue(text, this.options.tags.valueParsers) });
+  }
+
+  addPi(name){
+    if(!this.options.ignorePiTags){
+      const node = { [name]:[]}
+      if(this.attributes){
+        node[":@"] = this.attributes;
+      }
+      this.currentNode.push(node);
+    }
+    this.attributes = {};
+  }
+  getOutput(){
+    return this.root[rootName];
+  }
+}
+
+module.exports = OutputBuilder;
\ No newline at end of file

@@ -0,0 +1,155 @@
+
+
+const {buildOptions,registerCommonValueParsers} = require("./ParserOptionsBuilder");
+
+class OutputBuilder{
+  constructor(options){
+      this.options = buildOptions(options);
+      this.registeredParsers = registerCommonValueParsers();
+  }
+
+  registerValueParser(name,parserInstance){//existing name will override the parser without warning
+    this.registeredParsers[name] = parserInstance;
+  }
+
+  getInstance(){
+    return new JsObjBuilder(this.options, this.registeredParsers);
+  }
+}
+
+const BaseOutputBuilder = require("./BaseOutputBuilder");
+const rootName = '^';
+
+class JsObjBuilder extends BaseOutputBuilder{
+
+  constructor(options,registeredParsers) {
+    super();
+    //hold the raw detail of a tag and sequence with reference to the output
+    this.tagsStack = [];
+    this.options = options;
+    this.registeredParsers = registeredParsers;
+
+    this.root = {};
+    this.parent = this.root;
+    this.tagName = rootName;
+    this.value = {};
+    this.textValue = "";
+    this.attributes = {};
+  }
+
+  addTag(tag){
+
+    let value = "";
+    if( !isEmpty(this.attributes)){
+      value = {};
+      if(this.options.attributes.groupBy){
+        value[this.options.attributes.groupBy] = this.attributes;
+      }else{
+        value = this.attributes;
+      }
+    }
+
+    this.tagsStack.push([this.tagName, this.textValue, this.value]); //parent tag, parent text value, parent tag value (jsobj)
+    this.tagName = tag.name;
+    this.value = value;
+    this.textValue = "";
+    this.attributes = {};
+  }
+
+  /**
+   * Check if the node should be added by checking user's preference
+   * @param {Node} node 
+   * @returns boolean: true if the node should not be added
+   */
+  closeTag(){
+    const tagName = this.tagName;
+    let value = this.value;
+    let textValue = this.textValue;
+
+    //update tag text value
+    if(typeof value !== "object" && !Array.isArray(value)){
+      value = this.parseValue(textValue.trim(), this.options.tags.valueParsers);
+    }else if(textValue.length > 0){
+      value[this.options.nameFor.text] = this.parseValue(textValue.trim(), this.options.tags.valueParsers);
+    }
+
+    
+    let resultTag= {
+      tagName: this.tagName,
+      value: value
+    };
+
+    if(this.options.onTagClose !== undefined){
+      //TODO TagPathMatcher 
+      resultTag = this.options.onClose(this.tagName, value, this.textValue, new TagPathMatcher(this.tagsStack,node));
+
+      if(!resultTag) return;
+    }
+
+    //set parent node in scope
+    let arr = this.tagsStack.pop(); 
+    let parentTag = arr[2];
+    parentTag=this._addChildTo(resultTag.tagName, resultTag.value, parentTag);
+
+    this.tagName = arr[0];
+    this.textValue = arr[1];
+    this.value = parentTag;
+  }
+
+  _addChild(key, val){
+    if(typeof this.value === "string"){
+      this.value = { [this.options.nameFor.text] : this.value };
+    }
+
+    this._addChildTo(key, val, this.value);
+    // this.currentNode.leafType = false;
+    this.attributes = {};
+  }
+
+  _addChildTo(key, val, node){
+    if(typeof node === 'string') node = {};
+    if(!node[key]){
+      node[key] = val;
+    }else{ //Repeated
+      if(!Array.isArray(node[key])){ //but not stored as array
+        node[key] = [node[key]];
+      }
+      node[key].push(val);
+    }
+    return node;
+  }
+
+
+  /**
+   * Add text value child node 
+   * @param {string} text 
+   */
+  addValue(text){
+    //TODO: use bytes join
+    if(this.textValue.length > 0) this.textValue += " " + text;
+    else this.textValue = text;
+  }
+
+  addPi(name){
+    let value = "";
+    if( !isEmpty(this.attributes)){
+      value = {};
+      if(this.options.attributes.groupBy){
+        value[this.options.attributes.groupBy] = this.attributes;
+      }else{
+        value = this.attributes;
+      }
+    }
+    this._addChild(name, value);
+    
+  }
+  getOutput(){
+    return this.value;
+  }
+}
+
+function isEmpty(obj) {
+  return Object.keys(obj).length === 0;
+}
+
+module.exports = OutputBuilder;
\ No newline at end of file

@@ -0,0 +1,94 @@
+const trimParser = require("../valueParsers/trim")
+const booleanParser = require("../valueParsers/booleanParser")
+const currencyParser = require("../valueParsers/currency")
+const numberParser = require("../valueParsers/number")
+
+const defaultOptions={
+  nameFor:{
+    text: "#text",
+    comment: "",
+    cdata: "",
+  },
+  // onTagClose: () => {},
+  // onAttribute: () => {},
+  piTag: false,
+  declaration: false, //"?xml"
+  tags: {
+    valueParsers: [
+      // "trim",
+      // "boolean",
+      // "number",
+      // "currency",
+      // "date",
+    ]
+  },
+  attributes:{
+    prefix: "@_",
+    suffix: "",
+    groupBy: "",
+    
+    valueParsers: [
+      // "trim",
+      // "boolean",
+      // "number",
+      // "currency",
+      // "date",
+    ]
+  }
+}
+function buildOptions(options){
+  //clone
+  const finalOptions = { ... defaultOptions};
+
+  //add config missed in cloning
+  finalOptions.tags.valueParsers.push("trim")
+  finalOptions.tags.valueParsers.push("boolean")
+  finalOptions.tags.valueParsers.push("number")
+  finalOptions.tags.valueParsers.push("currency")
+
+  //add config missed in cloning
+  finalOptions.attributes.valueParsers.push("trim")
+  finalOptions.attributes.valueParsers.push("boolean")
+  finalOptions.attributes.valueParsers.push("number")
+  finalOptions.attributes.valueParsers.push("currency")
+
+  copyProperties(finalOptions,options);
+  return finalOptions;
+}
+
+function copyProperties(target, source) {
+  for (let key in source) {
+    if (source.hasOwnProperty(key)) {
+      if (typeof source[key] === 'object' && !Array.isArray(source[key])) {
+        // Recursively copy nested properties
+        if (typeof target[key] === 'undefined') {
+          target[key] = {};
+        }
+        copyProperties(target[key], source[key]);
+      } else {
+        // Copy non-nested properties
+        target[key] = source[key];
+      }
+    }
+  }
+}
+
+function registerCommonValueParsers(){
+  return {
+    "trim": new trimParser(),
+    // "join": this.entityParser.parse,
+    "boolean": new booleanParser(),
+    "number": new numberParser({
+          hex: true,
+          leadingZeros: true,
+          eNotation: true
+        }),
+    "currency": new currencyParser(),
+    // "date": this.entityParser.parse,
+  }
+}
+
+module.exports = {
+  buildOptions : buildOptions,
+  registerCommonValueParsers: registerCommonValueParsers
+}
\ No newline at end of file

@@ -0,0 +1,81 @@
+class TagPath{
+  constructor(pathStr){
+    let text = "";
+    let tName = "";
+    let pos;
+    let aName = "";
+    let aVal = "";
+    this.stack = []
+
+    for (let i = 0; i < pathStr.length; i++) {
+      let ch = pathStr[i];
+      if(ch === " ") {
+        if(text.length === 0) continue;        
+        tName = text; text = "";
+      }else if(ch === "["){
+        if(tName.length === 0){
+          tName = text; text = "";
+        }
+        i++;
+        for (; i < pathStr.length; i++) {
+          ch = pathStr[i];
+          if(ch=== "=") continue;
+          else if(ch=== "]") {aName = text.trim(); text=""; break; i--;}
+          else if(ch === "'" || ch === '"'){
+            let attrEnd = pathStr.indexOf(ch,i+1);
+            aVal = pathStr.substring(i+1, attrEnd);
+            i = attrEnd;
+          }else{
+            text +=ch;
+          }
+        }
+      }else if(ch !== " " && text.length === 0 && tName.length > 0){//reading tagName
+        //save previous tag
+        this.stack.push(new TagPathNode(tName,pos,aName,aVal));
+        text = ch; tName = ""; aName = ""; aVal = "";
+      }else{
+        text+=ch;
+      }
+    }
+
+    //last tag in the path
+    if(tName.length >0 || text.length>0){
+      this.stack.push(new TagPathNode(text||tName,pos,aName,aVal));
+    }
+  }
+
+  match(tagStack,node){
+    if(this.stack[0].name !== "*"){
+      if(this.stack.length !== tagStack.length +1) return false;
+  
+      //loop through tagPath and tagStack and match
+      for (let i = 0; i < this.tagStack.length; i++) {
+        if(!this.stack[i].match(tagStack[i])) return false;
+      }
+    }
+    if(!this.stack[this.stack.length - 1].match(node)) return false;
+    return true;
+  }
+}
+
+class TagPathNode{
+  constructor(name,position,attrName,attrVal){
+    this.name = name;
+    this.position = position;
+    this.attrName = attrName,
+    this.attrVal = attrVal;
+  }
+
+  match(node){
+    let matching = true;
+    matching = node.name === this.name;
+    if(this.position) matching = node.position === this.position;
+    if(this.attrName) matching = node.attrs[this.attrName !== undefined];
+    if(this.attrVal) matching = node.attrs[this.attrName !== this.attrVal];
+    return matching;
+  }
+}
+
+// console.log((new TagPath("* b[b]")).stack);
+// console.log((new TagPath("a[a] b[b] c")).stack);
+// console.log((new TagPath(" b [ b= 'cf  sdadwa' ] a  ")).stack);
\ No newline at end of file

@@ -0,0 +1,15 @@
+const TagPath = require("./TagPath");
+
+class TagPathMatcher{
+  constructor(stack,node){
+    this.stack = stack;
+    this.node= node;
+  }
+
+  match(path){
+    const tagPath = new TagPath(path);
+    return tagPath.match(this.stack, this.node);
+  }
+}
+
+module.exports = TagPathMatcher;
\ No newline at end of file

@@ -0,0 +1,20 @@
+function boolParserExt(val){
+    if(isArray(val)){
+        for (let i = 0; i < val.length; i++) {
+            val[i] = parse(val[i])
+        }
+    }else{
+        val = parse(val)
+    }
+    return val;
+}
+
+function parse(val){
+    if (typeof val === 'string') {
+        const temp = val.toLowerCase();
+        if(temp === 'true' || temp ==="yes" || temp==="1") return true;
+        else if(temp === 'false' || temp ==="no" || temp==="0") return false;
+    }
+    return val;
+}
+module.exports = boolParserExt;
\ No newline at end of file

@@ -0,0 +1,23 @@
+class boolParser{
+    constructor(trueList, falseList){
+        if(trueList)
+            this.trueList = trueList;
+        else
+            this.trueList = ["true"];
+        
+        if(falseList)
+            this.falseList = falseList;
+        else
+            this.falseList = ["false"];
+    }
+    parse(val){
+        if (typeof val === 'string') {
+            //TODO: performance: don't convert
+            const temp = val.toLowerCase();
+            if(this.trueList.indexOf(temp) !== -1) return true;
+            else if(this.falseList.indexOf(temp) !== -1 ) return false;
+        }
+        return val;
+    }
+}
+module.exports = boolParser;
\ No newline at end of file

@@ -0,0 +1,31 @@
+
+const localeMap = {
+    "$":"en-US",
+    "€":"de-DE",
+    "£":"en-GB",
+    "¥":"ja-JP",
+    "₹":"en-IN",
+}
+
+const currencyCheckRegex = /^\s*(?:-|\+)?(?:\d+|\d{1,3}(?:,\d{3})+)?(?:\.\d{1,2})?\s*(?:\$|€|¥|₹)?\s*$/u;
+
+class CurrencyParser{
+    constructor(options){
+        this.options = options;
+    }
+    parse(val){
+        if (typeof val === 'string') {
+            if(val.indexOf(",,") !== -1 && val.indexOf(".." !== -1)){
+                const match = val.match(currencyCheckRegex);
+                if(match){
+                    const locale = this.options.locale || localeMap[match[2]||match[5]||"₹"];
+                    const formatter = new Intl.NumberFormat(locale)
+                    val = val.replace(/[^0-9,.]/g, '').trim();
+                    val = Number(val.replace(formatter.format(1000)[1], ''));
+                }
+            }
+        }
+        return val;
+    }
+}
+module.exports = CurrencyParser;
\ No newline at end of file

@@ -0,0 +1,105 @@
+const ampEntity = { regex: /&(amp|#38|#x26);/g, val : "&"};
+const htmlEntities = {
+    "space": { regex: /&(nbsp|#160);/g, val: " " },
+    // "lt" : { regex: /&(lt|#60);/g, val: "<" },
+    // "gt" : { regex: /&(gt|#62);/g, val: ">" },
+    // "amp" : { regex: /&(amp|#38);/g, val: "&" },
+    // "quot" : { regex: /&(quot|#34);/g, val: "\"" },
+    // "apos" : { regex: /&(apos|#39);/g, val: "'" },
+    "cent" : { regex: /&(cent|#162);/g, val: "¢" },
+    "pound" : { regex: /&(pound|#163);/g, val: "£" },
+    "yen" : { regex: /&(yen|#165);/g, val: "¥" },
+    "euro" : { regex: /&(euro|#8364);/g, val: "€" },
+    "copyright" : { regex: /&(copy|#169);/g, val: "©" },
+    "reg" : { regex: /&(reg|#174);/g, val: "®" },
+    "inr" : { regex: /&(inr|#8377);/g, val: "₹" },
+};
+
+class EntitiesParser{
+    constructor(replaceHtmlEntities) {
+      this.replaceHtmlEntities = replaceHtmlEntities;
+      this.docTypeEntities = {};
+      this.lastEntities = {
+        "apos" : { regex: /&(apos|#39|#x27);/g, val : "'"},
+        "gt" : { regex: /&(gt|#62|#x3E);/g, val : ">"},
+        "lt" : { regex: /&(lt|#60|#x3C);/g, val : "<"},
+        "quot" : { regex: /&(quot|#34|#x22);/g, val : "\""},
+      };
+    }
+
+    addExternalEntities(externalEntities){
+        const entKeys = Object.keys(externalEntities);
+        for (let i = 0; i < entKeys.length; i++) {
+          const ent = entKeys[i];
+          this.addExternalEntity(ent,externalEntities[ent])
+        }
+    }
+    addExternalEntity(key,val){
+      validateEntityName(key);
+      if(val.indexOf("&") !== -1) {
+        reportWarning(`Entity ${key} is not added as '&' is found in value;`)
+        return;
+      }else{
+        this.lastEntities[ent] = {
+          regex: new RegExp("&"+key+";","g"),
+          val : val
+        }
+      }
+    }
+
+    addDocTypeEntities(entities){
+        const entKeys = Object.keys(entities);
+        for (let i = 0; i < entKeys.length; i++) {
+          const ent = entKeys[i];
+          this.docTypeEntities[ent] = {
+             regex: new RegExp("&"+ent+";","g"),
+             val : entities[ent]
+          }
+        }
+    }
+
+    parse(val){
+        return this.replaceEntitiesValue(val)
+    }
+
+    /**
+     * 1. Replace DOCTYPE entities 
+     * 2. Replace external entities 
+     * 3. Replace HTML entities if asked
+     * @param {string} val 
+     */
+    replaceEntitiesValue(val){
+        if(typeof val === "string" && val.length > 0){
+            for(let entityName in this.docTypeEntities){
+                const entity = this.docTypeEntities[entityName];
+                val = val.replace( entity.regx, entity.val);
+              }
+              for(let entityName in this.lastEntities){
+                const entity = this.lastEntities[entityName];
+                val = val.replace( entity.regex, entity.val);
+              }
+              if(this.replaceHtmlEntities){
+                for(let entityName in htmlEntities){
+                  const entity = htmlEntities[entityName];
+                  val = val.replace( entity.regex, entity.val);
+                }
+              }
+            val = val.replace( ampEntity.regex, ampEntity.val);
+        }
+        return val;
+    }
+};
+
+//an entity name should not contains special characters that may be used in regex
+//Eg !?\\\/[]$%{}^&*()<>
+const specialChar = "!?\\\/[]$%{}^&*()<>|+";
+
+function validateEntityName(name){
+    for (let i = 0; i < specialChar.length; i++) {
+        const ch = specialChar[i];
+        if(name.indexOf(ch) !== -1) throw new Error(`Invalid character ${ch} in entity name`);
+    }
+    return name;
+}
+
+module.exports = EntitiesParser;
\ No newline at end of file

@@ -0,0 +1,14 @@
+/**
+ * 
+ * @param {array} val 
+ * @param {string} by 
+ * @returns 
+ */
+function join(val, by=" "){
+    if(isArray(val)){
+        val.join(by)
+    }
+    return val;
+}
+
+module.exports = join;
\ No newline at end of file

@@ -0,0 +1,16 @@
+const toNumber = require("strnum");
+
+
+class numParser{
+    constructor(options){
+        this.options = options;
+    }
+    parse(val){
+        if (typeof val === 'string') {
+            val = toNumber(val,this.options);
+        }
+        return val;
+    }
+}
+
+module.exports = numParser;
\ No newline at end of file

@@ -0,0 +1,8 @@
+class trimmer{
+    parse(val){
+        if(typeof val === "string") return val.trim();
+        else return val;
+    }
+}
+
+module.exports = trimmer;
\ No newline at end of file

@@ -0,0 +1,237 @@
+const StringSource = require("./inputSource/StringSource");
+const BufferSource = require("./inputSource/BufferSource");
+const {readTagExp,readClosingTagName} = require("./XmlPartReader");
+const {readComment, readCdata,readDocType,readPiTag} = require("./XmlSpecialTagsReader");
+const TagPath = require("./TagPath");
+const TagPathMatcher = require("./TagPathMatcher");
+const EntitiesParser = require('./EntitiesParser');
+
+//To hold the data of current tag
+//This is usually used to compare jpath expression against current tag
+class TagDetail{
+  constructor(name){
+    this.name = name;
+    this.position = 0;
+    // this.attributes = {};
+  }
+}
+
+class Xml2JsParser {
+    constructor(options) {
+      this.options = options;
+      
+      this.currentTagDetail = null;
+      this.tagTextData = "";
+      this.tagsStack = [];
+      this.entityParser = new EntitiesParser(options.htmlEntities);
+      this.stopNodes = [];
+      for (let i = 0; i < this.options.stopNodes.length; i++) {
+        this.stopNodes.push(new TagPath(this.options.stopNodes[i]));
+      }
+    }
+
+    parse(strData) {
+        this.source = new StringSource(strData);
+        this.parseXml();
+        return this.outputBuilder.getOutput();
+    }
+    parseBytesArr(data) {
+        this.source = new BufferSource(data );
+        this.parseXml();
+        return this.outputBuilder.getOutput();
+    }
+  
+    parseXml() {
+      //TODO: Separate TagValueParser as separate class. So no scope issue in node builder class 
+
+      //OutputBuilder should be set in XML Parser
+      this.outputBuilder = this.options.OutputBuilder.getInstance(this.options);
+      this.root = { root: true};
+      this.currentTagDetail = this.root;
+
+      while(this.source.canRead()){
+        let ch = this.source.readCh();
+        if (ch === "") break;
+        
+        if(ch === "<"){//tagStart
+          let nextChar = this.source.readChAt(0);
+          if (nextChar === "" ) throw new Error("Unexpected end of source");
+          
+        
+          if(nextChar === "!" || nextChar === "?"){
+            this.source.updateBufferBoundary();
+            //previously collected text should be added to current node
+            this.addTextNode(); 
+            
+            this.readSpecialTag(nextChar);// Read DOCTYPE, comment, CDATA, PI tag
+          }else if(nextChar === "/"){
+            this.source.updateBufferBoundary();
+            this.readClosingTag();
+            // console.log(this.source.buffer.length, this.source.readable);
+            // console.log(this.tagsStack.length);
+          }else{//opening tag
+            this.readOpeningTag();
+          }
+        }else{
+          this.tagTextData += ch;
+        }
+      }//End While loop
+      if(this.tagsStack.length > 0 || ( this.tagTextData !== "undefined" && this.tagTextData.trimEnd().length > 0) ) throw new Error("Unexpected data in the end of document");
+    }
+  
+    /**
+     * read closing paired tag. Set parent tag in scope.
+     * skip a node on user's choice
+     */
+    readClosingTag(){
+      const tagName = this.processTagName(readClosingTagName(this.source));
+      // console.log(tagName, this.tagsStack.length);
+      this.validateClosingTag(tagName);
+      // All the text data collected, belongs to current tag.
+      if(!this.currentTagDetail.root) this.addTextNode();
+      this.outputBuilder.closeTag();
+      // Since the tag is closed now, parent tag comes in scope
+      this.currentTagDetail = this.tagsStack.pop(); 
+    }
+
+    validateClosingTag(tagName){
+      // This can't be unpaired tag, or a stop tag.
+      if(this.isUnpaired(tagName) || this.isStopNode(tagName)) throw new Error(`Unexpected closing tag '${tagName}'`);
+      // This must match with last opening tag
+      else if(tagName !== this.currentTagDetail.name) 
+        throw new Error(`Unexpected closing tag '${tagName}' expecting '${this.currentTagDetail.name}'`)
+    }
+
+    /**
+     * Read paired, unpaired, self-closing, stop and special tags.
+     * Create a new node
+     * Push paired tag in stack.
+     */
+    readOpeningTag(){
+      //save previously collected text data to current node
+      this.addTextNode();
+
+      //create new tag
+      let tagExp = readTagExp(this, ">" );
+      
+      // process and skip from tagsStack For unpaired tag, self closing tag, and stop node
+      const tagDetail = new TagDetail(tagExp.tagName);
+      if(this.isUnpaired(tagExp.tagName)) {
+        //TODO: this will lead 2 extra stack operation
+        this.outputBuilder.addTag(tagDetail);
+        this.outputBuilder.closeTag();
+      } else if(tagExp.selfClosing){
+        this.outputBuilder.addTag(tagDetail);
+        this.outputBuilder.closeTag();
+      } else if(this.isStopNode(this.currentTagDetail)){
+        // TODO: let's user set a stop node boundary detector for complex contents like script tag
+        //TODO: pass tag name only to avoid string operations
+        const content = source.readUptoCloseTag(`</${tagExp.tagName}`);
+        this.outputBuilder.addTag(tagDetail);
+        this.outputBuilder.addValue(content);
+        this.outputBuilder.closeTag();
+      }else{//paired tag
+        //set new nested tag in scope.
+        this.tagsStack.push(this.currentTagDetail);
+        this.outputBuilder.addTag(tagDetail);
+        this.currentTagDetail = tagDetail;
+      }
+      // console.log(tagExp.tagName,this.tagsStack.length);
+      // this.options.onClose()
+
+    }
+
+    readSpecialTag(startCh){
+      if(startCh == "!"){
+        let nextChar = this.source.readCh();
+        if (nextChar === null || nextChar === undefined) throw new Error("Unexpected ending of the source");
+        
+        if(nextChar === "-"){//comment
+          readComment(this);
+        }else if(nextChar === "["){//CDATA
+          readCdata(this);
+        }else if(nextChar === "D"){//DOCTYPE
+          readDocType(this);
+        }
+      }else if(startCh === "?"){
+        readPiTag(this);
+      }else{
+        throw new Error(`Invalid tag '<${startCh}' at ${this.source.line}:${this.source.col}`)
+      }
+    }
+    addTextNode = function() {
+      // if(this.currentTagDetail){
+        //save text as child node
+        // if(this.currentTagDetail.tagname !== '!xml')
+        if (this.tagTextData !== undefined && this.tagTextData !== "") { //store previously collected data as textNode
+          if(this.tagTextData.trim().length > 0){
+            //TODO: shift parsing to output builder
+
+            this.outputBuilder.addValue(this.replaceEntities(this.tagTextData));
+          }
+          this.tagTextData = "";
+        }
+      // }
+    }
+
+    processAttrName(name){
+      if(name === "__proto__") name  = "#__proto__";
+      name = resolveNameSpace(name, this.removeNSPrefix);
+      return name;
+    }
+    
+    processTagName(name){
+      if(name === "__proto__") name  = "#__proto__";
+      name = resolveNameSpace(name, this.removeNSPrefix);
+      return name;
+    }
+
+    /**
+     * Generate tags path from tagsStack
+     */
+    tagsPath(tagName){
+      //TODO: return TagPath Object. User can call match method with path
+      return "";
+    }
+
+    isUnpaired(tagName){
+      return this.options.tags.unpaired.indexOf(tagName) !== -1;
+    }
+
+    /**
+     * valid expressions are 
+     * tag nested
+     * * nested
+     * tag nested[attribute]
+     * tag nested[attribute=""]
+     * tag nested[attribute!=""]
+     * tag nested:0 //for future
+     * @param {string} tagName 
+     * @returns 
+     */
+    isStopNode(node){
+      for (let i = 0; i < this.stopNodes.length; i++) {
+        const givenPath = this.stopNodes[i];
+        if(givenPath.match(this.tagsStack, node)) return true;
+      }
+      return false 
+    }
+
+    replaceEntities(text){
+      //TODO: if option is set then replace entities
+      return this.entityParser.parse(text)
+    }
+}
+
+function resolveNameSpace(name, removeNSPrefix) {
+  if (removeNSPrefix) {
+    const parts = name.split(':');
+    if(parts.length === 2){
+      if (parts[0] === 'xmlns') return '';
+      else return parts[1];
+    }else reportError(`Multiple namespaces ${name}`)
+  }
+  return name;
+}
+
+module.exports = Xml2JsParser;
\ No newline at end of file

@@ -0,0 +1,85 @@
+const { buildOptions} = require("./OptionsBuilder");
+const Xml2JsParser = require("./Xml2JsParser");
+
+class XMLParser{
+    
+    constructor(options){
+        this.externalEntities = {};
+        this.options = buildOptions(options);
+        // console.log(this.options)
+    }
+    /**
+     * Parse XML data string to JS object 
+     * @param {string|Buffer} xmlData 
+     * @param {boolean|Object} validationOption 
+     */
+    parse(xmlData){
+        if(Array.isArray(xmlData) && xmlData.byteLength !== undefined){
+            return this.parse(xmlData);
+        }else if( xmlData.toString){
+            xmlData = xmlData.toString();
+        }else{
+            throw new Error("XML data is accepted in String or Bytes[] form.")
+        }
+        // if( validationOption){
+        //     if(validationOption === true) validationOption = {}; //validate with default options
+            
+        //     const result = validator.validate(xmlData, validationOption);
+        //     if (result !== true) {
+        //       throw Error( `${result.err.msg}:${result.err.line}:${result.err.col}` )
+        //     }
+        //   }
+        const parser = new Xml2JsParser(this.options);
+        parser.entityParser.addExternalEntities(this.externalEntities);
+        return parser.parse(xmlData);
+    }
+    /**
+     * Parse XML data buffer to JS object 
+     * @param {string|Buffer} xmlData 
+     * @param {boolean|Object} validationOption 
+     */
+    parseBytesArr(xmlData){
+        if(Array.isArray(xmlData) && xmlData.byteLength !== undefined){
+        }else{
+            throw new Error("XML data is accepted in Bytes[] form.")
+        }
+        const parser = new Xml2JsParser(this.options);
+        parser.entityParser.addExternalEntities(this.externalEntities);
+        return parser.parseBytesArr(xmlData);
+    }
+    /**
+     * Parse XML data stream to JS object 
+     * @param {fs.ReadableStream} xmlDataStream 
+     */
+    parseStream(xmlDataStream){
+        if(!isStream(xmlDataStream)) throw new Error("FXP: Invalid stream input");
+        
+        const orderedObjParser = new Xml2JsParser(this.options);
+        orderedObjParser.entityParser.addExternalEntities(this.externalEntities);
+        return orderedObjParser.parseStream(xmlDataStream);
+    }
+
+    /**
+     * Add Entity which is not by default supported by this library
+     * @param {string} key 
+     * @param {string} value 
+     */
+    addEntity(key, value){
+        if(value.indexOf("&") !== -1){
+            throw new Error("Entity value can't have '&'")
+        }else if(key.indexOf("&") !== -1 || key.indexOf(";") !== -1){
+            throw new Error("An entity must be set without '&' and ';'. Eg. use '#xD' for '
'")
+        }else if(value === "&"){
+            throw new Error("An entity with value '&' is not permitted");
+        }else{
+            this.externalEntities[key] = value;
+        }
+    }
+}
+
+function isStream(stream){
+    if(stream && typeof stream.read === "function" && typeof stream.on === "function" && typeof stream.readableEnded === "boolean") return true;
+    return false;
+}
+
+module.exports = XMLParser;
\ No newline at end of file

@@ -0,0 +1,212 @@
+'use strict';
+
+/**
+ * find paired tag for a stop node
+ * @param {string} xmlDoc 
+ * @param {string} tagName 
+ * @param {number} i : start index
+ */
+function readStopNode(xmlDoc, tagName, i){
+    const startIndex = i;
+    // Starting at 1 since we already have an open tag
+    let openTagCount = 1;
+  
+    for (; i < xmlDoc.length; i++) {
+      if( xmlDoc[i] === "<"){ 
+        if (xmlDoc[i+1] === "/") {//close tag
+            const closeIndex = findSubStrIndex(xmlDoc, ">", i, `${tagName} is not closed`);
+            let closeTagName = xmlDoc.substring(i+2,closeIndex).trim();
+            if(closeTagName === tagName){
+              openTagCount--;
+              if (openTagCount === 0) {
+                return {
+                  tagContent: xmlDoc.substring(startIndex, i),
+                  i : closeIndex
+                }
+              }
+            }
+            i=closeIndex;
+          } else if(xmlDoc[i+1] === '?') { 
+            const closeIndex = findSubStrIndex(xmlDoc, "?>", i+1, "StopNode is not closed.")
+            i=closeIndex;
+          } else if(xmlDoc.substr(i + 1, 3) === '!--') { 
+            const closeIndex = findSubStrIndex(xmlDoc, "-->", i+3, "StopNode is not closed.")
+            i=closeIndex;
+          } else if(xmlDoc.substr(i + 1, 2) === '![') { 
+            const closeIndex = findSubStrIndex(xmlDoc, "]]>", i, "StopNode is not closed.") - 2;
+            i=closeIndex;
+          } else {
+            const tagData = readTagExp(xmlDoc, i, '>')
+  
+            if (tagData) {
+              const openTagName = tagData && tagData.tagName;
+              if (openTagName === tagName && tagData.tagExp[tagData.tagExp.length-1] !== "/") {
+                openTagCount++;
+              }
+              i=tagData.closeIndex;
+            }
+          }
+        }
+    }//end for loop
+}
+
+/**
+ * Read closing tag name
+ * @param {Source} source 
+ * @returns tag name
+ */
+function readClosingTagName(source){
+  let text = ""; //temporary data
+  while(source.canRead()){
+    let ch = source.readCh();
+    // if (ch === null || ch === undefined) break;
+    // source.updateBuffer();
+
+    if (ch === ">") return text.trimEnd();
+    else text += ch;
+  }
+  throw new Error(`Unexpected end of source. Reading '${substr}'`);
+}
+
+/**
+ * Read XML tag and build attributes map
+ * This function can be used to read normal tag, pi tag.
+ * This function can't be used to read comment, CDATA, DOCTYPE.
+ * Eg <tag attr = ' some"' attr= ">" bool>
+ * @param {string} xmlDoc 
+ * @param {number} startIndex starting index
+ * @returns tag expression includes tag name & attribute string 
+ */
+function readTagExp(parser) {
+  let inSingleQuotes = false;
+  let inDoubleQuotes = false;
+  let i;
+  let EOE = false;
+
+  for (i = 0; parser.source.canRead(i); i++) {
+    const char = parser.source.readChAt(i);
+
+    if (char === "'" && !inDoubleQuotes) {
+      inSingleQuotes = !inSingleQuotes;
+    } else if (char === '"' && !inSingleQuotes) {
+      inDoubleQuotes = !inDoubleQuotes;
+    } else if (char === '>' && !inSingleQuotes && !inDoubleQuotes) {
+      // If not inside quotes, stop reading at '>'
+      EOE = true;
+      break;
+    }
+
+  }
+  if(inSingleQuotes || inDoubleQuotes){
+    throw new Error("Invalid attribute expression. Quote is not properly closed");
+  }else if(!EOE) throw new Error("Unexpected closing of source. Waiting for '>'");
+  
+  
+  const exp = parser.source.readStr(i);
+  parser.source.updateBufferBoundary(i + 1);
+  return buildTagExpObj(exp, parser)
+}
+
+function readPiExp(parser) {
+  let inSingleQuotes = false;
+  let inDoubleQuotes = false;
+  let i;
+  let EOE = false;
+
+  for (i = 0; parser.source.canRead(i) ; i++) {
+    const currentChar = parser.source.readChAt(i);
+    const nextChar =  parser.source.readChAt(i+1);
+
+    if (currentChar === "'" && !inDoubleQuotes) {
+      inSingleQuotes = !inSingleQuotes;
+    } else if (currentChar === '"' && !inSingleQuotes) {
+      inDoubleQuotes = !inDoubleQuotes;
+    }
+
+    if (!inSingleQuotes && !inDoubleQuotes) {
+      if (currentChar === '?' && nextChar === '>') {
+        EOE = true;
+        break; // Exit the loop when '?>' is found
+      }
+    }
+  }
+  if(inSingleQuotes || inDoubleQuotes){
+    throw new Error("Invalid attribute expression. Quote is not properly closed in PI tag expression");
+  }else if(!EOE) throw new Error("Unexpected closing of source. Waiting for '?>'");
+  
+  if(!parser.options.attributes.ignore){
+    //TODO: use regex to verify attributes if not set to ignore
+  }
+
+  const exp = parser.source.readStr(i);
+  parser.source.updateBufferBoundary(i + 1);
+  return buildTagExpObj(exp, parser)
+}
+
+function buildTagExpObj(exp, parser){
+  const tagExp = {
+    tagName: "",
+    selfClosing: false
+  };
+  let attrsExp = "";
+
+  if(exp[exp.length -1] === "/") tagExp.selfClosing = true;
+
+  //separate tag name
+  let i = 0;
+  for (; i < exp.length; i++) {
+    const char = exp[i];
+    if(char === " "){
+      tagExp.tagName = exp.substring(0, i);
+      attrsExp = exp.substring(i + 1);
+      break;
+    }
+  }
+  //only tag
+  if(tagExp.tagName.length === 0 && i === exp.length)tagExp.tagName = exp;
+
+  tagExp.tagName = tagExp.tagName.trimEnd();
+
+  if(!parser.options.attributes.ignore && attrsExp.length > 0){
+    parseAttributesExp(attrsExp,parser)
+  }
+
+  return tagExp;
+}
+
+const attrsRegx = new RegExp('([^\\s=]+)\\s*(=\\s*([\'"])([\\s\\S]*?)\\3)?', 'gm');
+
+function parseAttributesExp(attrStr, parser) {
+  const matches = getAllMatches(attrStr, attrsRegx);
+  const len = matches.length; //don't make it inline
+  for (let i = 0; i < len; i++) {
+    let attrName = parser.processAttrName(matches[i][1]);
+    let attrVal = parser.replaceEntities(matches[i][4] || true);
+    
+    parser.outputBuilder.addAttribute(attrName, attrVal);
+  }
+}
+
+
+const getAllMatches = function(string, regex) {
+  const matches = [];
+  let match = regex.exec(string);
+  while (match) {
+    const allmatches = [];
+    allmatches.startIndex = regex.lastIndex - match[0].length;
+    const len = match.length;
+    for (let index = 0; index < len; index++) {
+      allmatches.push(match[index]);
+    }
+    matches.push(allmatches);
+    match = regex.exec(string);
+  }
+  return matches;
+};
+
+module.exports = {
+    readStopNode: readStopNode,
+    readClosingTagName: readClosingTagName,
+    readTagExp: readTagExp,
+    readPiExp: readPiExp,
+}
\ No newline at end of file

@@ -0,0 +1,118 @@
+const {readPiExp} = require("./XmlPartReader");
+
+function readCdata(parser){
+  //<![ are already read till this point
+  let str = parser.source.readStr(6); //CDATA[
+  parser.source.updateBufferBoundary(6);
+
+  if(str !== "CDATA[") throw new Error(`Invalid CDATA expression at ${parser.source.line}:${parser.source.cols}`);
+
+  let text = parser.source.readUpto("]]>");
+  parser.outputBuilder.addCdata(text);
+}
+function readPiTag(parser){
+  //<? are already read till this point
+  let tagExp = readPiExp(parser, "?>");
+  if(!tagExp) throw new Error("Invalid Pi Tag expression.");
+
+  if (tagExp.tagName === "?xml") {//TODO: test if tagName is just xml
+    parser.outputBuilder.addDeclaration();
+  } else {
+    parser.outputBuilder.addPi("?"+tagExp.tagName);
+  }
+}
+
+function readComment(parser){
+  //<!- are already read till this point
+  let ch = parser.source.readCh();
+  if(ch !== "-") throw new Error(`Invalid comment expression at ${parser.source.line}:${parser.source.cols}`);
+
+  let text = parser.source.readUpto("-->");
+  parser.outputBuilder.addComment(text);
+}
+
+const DOCTYPE_tags = {
+  "EL":/^EMENT\s+([^\s>]+)\s+(ANY|EMPTY|\(.+\)\s*$)/m,
+  "AT":/^TLIST\s+[^\s]+\s+[^\s]+\s+[^\s]+\s+[^\s]+\s+$/m,
+  "NO":/^TATION.+$/m
+}
+function readDocType(parser){
+  //<!D are already read till this point
+  let str = parser.source.readStr(6); //OCTYPE
+  parser.source.updateBufferBoundary(6);
+
+  if(str !== "OCTYPE") throw new Error(`Invalid DOCTYPE expression at ${parser.source.line}:${parser.source.cols}`);
+
+  let hasBody = false, lastch = "";
+
+  while(parser.source.canRead()){
+    //TODO: use readChAt like used in partReader
+    let ch = parser.source.readCh();
+    if(hasBody){
+      if (ch === '<') { //Determine the tag type
+        let str = parser.source.readStr(2);
+        parser.source.updateBufferBoundary(2);
+        if(str === "EN"){ //ENTITY
+          let str = parser.source.readStr(4);
+          parser.source.updateBufferBoundary(4);
+          if(str !== "TITY") throw new Error("Invalid DOCTYPE ENTITY expression");
+
+          registerEntity(parser);
+        }else if(str === "!-") {//comment
+          readComment(parser);
+        }else{ //ELEMENT, ATTLIST, NOTATION
+          let dTagExp = parser.source.readUpto(">");
+          const regx = DOCTYPE_tags[str];
+          if(regx){
+            const match = dTagExp.match(regx);
+            if(!match) throw new Error("Invalid DOCTYPE");
+          }else throw new Error("Invalid DOCTYPE");
+        }
+      }else if( ch === '>' && lastch === "]"){//end of doctype
+        return;  
+      }
+    }else if( ch === '>'){//end of doctype
+      return;
+    }else if( ch === '['){
+      hasBody = true;
+    }else{
+      lastch = ch;
+    }
+  }//End While loop
+
+}
+
+function registerEntity(parser){
+  //read Entity
+  let attrBoundary="";
+  let name ="", val ="";
+  while(source.canRead()){
+    let ch = source.readCh();
+
+    if(attrBoundary){
+      if (ch === attrBoundary){
+        val = text;
+        text = ""
+      }
+    }else if(ch === " " || ch === "\t"){
+      if(!name){
+        name = text.trimStart();
+        text = "";
+      }
+    }else if (ch === '"' || ch === "'") {//start of attrBoundary
+      attrBoundary = ch;
+    }else if(ch === ">"){
+      parser.entityParser.addExternalEntity(name,val);
+      return;
+    }else{
+      text+=ch;
+    }
+  }
+}
+
+module.exports = {
+  readCdata: readCdata,
+  readComment:readComment,
+  readDocType:readDocType,
+  readPiTag:readPiTag
+}
\ No newline at end of file