Regulex: Regular Expression Excited!

Regulex

Regulex is a JavaScript Regular Expression Parser & Visualizer.

Features

• Written in pure JavaScript. No backend required.
• You can embed the graph on you own site through HTML iframe element.
• Detailed error message. In most cases it can point out the precise syntax error position.
• No support for octal escape. Yes it is a feature! ECMAScript strict mode doesn't allow octal escape in string, but many browsers still allow octal escape in regex. In regulex, DecimalEscape will always be treated as back reference. If the back reference is invalid, e.g. /\1/, /(\1)/, /(a)\2/, or DecimalEscape appears in charset（because in this case it can't be explained as back reference, e.g. /(ab)[\1]/, Regulex will always throw an error.

Install for Node.js

npm install regulex

Local Build for Browser

This command will generate bundle dist/regulex.js for browser side:

git checkout legacy
npm install -g requirejs
r.js -o build-config.js

API

Parse to AST

var parse = require("regulex").parse;
var re = /var\s+([a-zA-Z_]\w*);/ ;
console.log(parse(re.source));

Visualize

var parse = require("regulex").parse;
var visualize = require("regulex").visualize;
var Raphael = require('regulex').Raphael;
var re = /var\s+([a-zA-Z_]\w*);/;
var paper = Raphael("yourSvgContainerId", 0, 0);
try {
  visualize(parse(re.source), getRegexFlags(re), paper);
} catch(e) {
  if (e instanceof parse.RegexSyntaxError) {
    logError(re, e);
  } else {
    throw e;
  }
}

function logError(re, err) {
  var msg = ["Error:" + err.message, ""];
  if (typeof err.lastIndex === "number") {
    msg.push(re);
    msg.push(new Array(err.lastIndex).join("-") + "^");
  }
  console.log(msg.join("\n"));
}


function getRegexFlags(re) {
  var flags = "";
  flags += re.ignoreCase ? "i" : "";
  flags += re.global ? "g" : "";
  flags += re.multiline ? "m" : "";
  return flags;
}

Try it now: https://jex.im/regulex/

This project is under reconstruction!

Download Details:

Author: CJex
Source Code: https://github.com/CJex/regulex 
License: MIT license

#typescript #javascript #diagram #regex 

What is GEEK

Buddha Community

Mad Libs: Using regular expressions

From Tiny Python Projects by Ken Youens-Clark

Everyone loves Mad Libs! And everyone loves Python. This article shows you how to have fun with both and learn some programming skills along the way.

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Take 40% off Tiny Python Projects by entering fccclark into the discount code box at checkout at manning.com.

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When I was a wee lad, we used to play at Mad Libs for hours and hours. This was before computers, mind you, before televisions or radio or even paper! No, scratch that, we had paper. Anyway, the point is we only had Mad Libs to play, and we loved it! And now you must play!

We’ll write a program called mad.py  which reads a file given as a positional argument and finds all the placeholders noted in angle brackets like <verb>  or <adjective> . For each placeholder, we’ll prompt the user for the part of speech being requested like “Give me a verb” and “Give me an adjective.” (Notice that you’ll need to use the correct article.) Each value from the user replaces the placeholder in the text, and if the user says “drive” for “verb,” then <verb>  in the text replaces with drive . When all the placeholders have been replaced with inputs from the user, print out the new text.

#python #regular-expressions #python-programming #python3 #mad libs: using regular expressions #using regular expressions

Regular Expressions: What and Why?

Regular expressions is a powerful search and replace technique that you probably have used even without knowing. Be it your text editor’s “Find and Replace” feature, validation of your http request body using a third party npm module or your terminal’s ability to return list of files based on some pattern, all of them use Regular Expressions in one way or the other. It is not a concept that programmers must definitely learn but by knowing it you are able to reduce the complexity of your code in some cases.

_In this tutorial we will be learning the key concepts as well as some use cases of Regular Expressions in _javascript.

How do you write a Regular Expression?

There are two ways of writing Regular expressions in Javascript. One is by creating a **literal **and the other is using **RegExp **constructor.

//Literal
const myRegex=/cat/ig

//RegExp
const myRegex=new RegExp('cat','ig')

While both types of expressions will return the same output when tested on a particular string, the benefit of using the RegExp constructor is that it is evaluated at runtime hence allowing use of javascript variables for dynamic regular expressions. Moreover as seen in this benchmark test the RegExp constructor performs better than the literal regular expression in pattern matching.

The syntax in either type of expression consists of two parts:

• pattern : The pattern that has to be matched in a string.
• flags : these are modifiers which are rules that describe how pattern matching will be performed.

#regular-expressions #javascript #programming #js #regex #express

Regular Expressions in Python [With Examples]: How to Implement?

While processing raw data from any source, extracting the right information is important so that meaningful insights can be obtained from the data. Sometimes it becomes difficult to take out the specific pattern from the data especially in the case of textual data.

The textual data consist of paragraphs of information collected via survey forms, scrapping websites, and other sources. The Channing of different string accessors with pandas functions or other custom functions can get the work done, but what if a more specific pattern needs to be obtained? Regular expressions do this job with ease.

What is a Regular Expression (RegEx)?

Examples to Understand The Workaround

How to Implement it in Python?

Conclusion

#data science #python #regular expression #regular expression in python

Regular Expressions in Python [With Examples]: How to Implement? | upGrad blog

While processing raw data from any source, extracting the right information is important so that meaningful insights can be obtained from the data. Sometimes it becomes difficult to take out the specific pattern from the data especially in the case of textual data.

The textual data consist of paragraphs of information collected via survey forms, scrapping websites, and other sources. The Channing of different string accessors with pandas functions or other custom functions can get the work done, but what if a more specific pattern needs to be obtained? Regular expressions do this job with ease.

What is a Regular Expression (RegEx)?

A regular expression is a representation of a set of characters for strings. It presents a generalized formula for a particular pattern in the strings which helps in segregating the right information from the pool of data. The expression usually consists of symbols or characters that help in forming the rule but, at first glance, it may seem weird and difficult to grasp. These symbols have associated meanings that are described here.

Meta-characters in RegEx

1. ‘.’: is a wildcard, matches a single character (any character, but just once)
2. ^: denotes start of the string
3. $: denotes the end of the string
4. [ ]: matches one of the sets of characters within [ ]
5. [a-z]: matches one of the range of characters a,b,…,z
6. [^abc] : matches a character that is not a,b or c.
7. a|b: matches either a or b, where a and b are strings
8. () : provides scoping for operators
9. \ : enables escape for special characters (\t, \n, \b, .)
10. \b: matches word boundary
11. \d : any digit, equivalent to [0-9]
12. \D: any non digit, equivalent to [^0-9]
13. \s : any whitespace, equivalent to [ \t\n\r\f\v]
14. \S : any non-whitespace, equivalent to [^\t\n\r\f\v]
15. \w : any alphanumeric, equivalent to [a-zA-Z0-9_]
16. \W : any non-alphanumeric, equivalent to [^a-zA-Z0-9_]
17. ‘*’: matches zero or more occurrences
18. ‘+’: matches one or more occurrences
19. ‘?’: matches zero or one occurrence
20. {n}: exactly n repetitions, n>=0
21. {n,}: at least n repetitions
22. {,n}: at most n repetitions
23. {m,n}: at least m repetitions and at most n repetitions

#data science #python #regular expression #regular expression in python

How to Upload and Store Images in MySQL using Node.js and Express

Today we are going to explore the basic usage of Express-FileUpload. In addition to this, I will show you how you can save/update a user record with a profile image that you can upload.

Chapters:
0:00 Introduction:
1:16 NPM Project Setup
3:54 Creating Express Server
5:51 Setting up Layouts & Routes
9:46 Express Upload Form
21:50 User Card
33:40 Database
52:05 Ending

Source Files:
https://raddy.co.uk/blog/upload-and-store-images-in-mysql-using-node-js-express-express-fileupload-express-handlebars/

#node.js #express #express-fileupload #express-handlebars #mysql #upload and store images