Regular Expression to hack a source code

There are many quality open source code available in github and code.google . Now if we wish to hack some source code, the best way to learn how it works is to see a log where the function name is displayed in the order it is executed.

Insert Debug Code using Regular Expression

By this technique, we can find the function using regular expression and insert our debug code inside each function.

Lets illustrate with a Javascript  Source Code and Notepad++ IDE

Regular Expression to Find functions

((\w*)\s*[:|=]\s*function\(\w*\)\s*\{)

Debug Code to insert inside each functions

console.log("functionName");

Regular Expression to Insert Debug Code inside Functions

$1 \n\tconsole\.log\("$2"\)\;

A sample Javascript before inserting Debug code

var SyntaxHighlighter = function() {

    var sh = {

        all: function(params)

        {

            attachEvent(

                window,'description'

            );

        }

    };

}();

Javascript code after inserting Debug code using Regular Expression

var SyntaxHighlighter = function() {

      console.log("SyntaxHighlighter");

    var sh = {

        all: function(params)

        {

            console.log("all");

            attachEvent(

                window,'description'

            );

        }

    };

}();

Note: Please enable "Regular expression" and ". matches newline" in Search Mode in Replace box in Notepad++ for inserting inside more than 1 function using regular expression.

How this Regular Expression Works

Find Regex :

((\w*)\s*[:|=]\s*function\(\w*\)\s*\{)

Replace Regex:

$1 \n\tconsole\.log\("$2"\)\;

\w	All alphanumeric characters  a-z, A-Z, 0-9
*	Repeat the preceding character zero or many times
\w*	means any kind of names like "SyntaxHighlighter", "all" and not allowed are "Big Event", "get-Param" because it contains non alphanumeric characters like ' ' space, and '-'
(\w*)	means grouping it to a variable, the variable name is $1 or $2, or $3 depending on the order it is grouped.
\s	means any kind of space like ' ', or tab space, or new line, or carriage return
\s*	means any number of spaces or no space
[ ]	is to define a set of allowed characters sequence
|	means  a conditional OR
[:|=]	means either ':' or '=' character
\	Followed by a character means to either escape the special meaning of that character or it is to assign a special meaning to some normal characters. Like '\w' gives 'w' a special meaning to represent all alphanumeric characters and ‘\*' means to literally represent '*'
\( \) \{	is to escape their special meaning and represent that character literally
$1	is the 1st grouped variable and in our case "all: function(params) {"
$2	is the 2nd grouped variable and in our case "SyntaxHighlighter", "all"