regular_expressions.rb

##Regular Expressions
#Matches patterns
#RESOURCE 
#learning Pearl Regular Exrpressions; 
#Regaular expression cheatsheet; 
#Rubular.com

#If a match is found, the operator returns index of first match in string, otherwise it returns nil;

/hay/ #quotes are not needed;

/hay/ =~ 'haystack' => 0 #Remember 0 is considered true in Ruby; 

/ay/ =~ 'haystack' => 1

. #matches any character; 
* #means 0 or more;
+ #means 1 or more;
? #means 0 or 1;
^ #[^Bb] The class is inverted: it matches any character except those named.

/bet.y/ =~ 'betsy' #Dot has a special meaning, means any character can go there; 

/.etty/ =~ 'Betty' 

/bet*y/ =~ 'betty'
/bet*y/ =~ 'bey'
/bettttttt*y/ =~ 'bey' #The asterisk means the character immediately before; 

#This confused me a bit: 

/bet+y/ =~ '/bey/' #There has to be one or more; 
/bet*y/ =~ '/bey/' #There has to be zero or more; 

#Soecify a class of characters inside square brackets; 

/.etty/ =~ 'Betty'
/bet[st]y/ =~ 'betsy' #Create a class with letters that you want to select from; 

/[Bb]etty [0-9]/ =~ 'betty 5'

'vote,kick,nix'
/vote,[A-Za-z]+, [A-Za-z]+/ =~ 'vote,kick,nix' 
m = /vote,([A-Za-z]+), ([A-Za-z]+)/.match 'vote,knight,eric' #Need to add curly braces and will split into an array into an object
m[0]
m[1]
m[2]

#GREP globally replace regular expressions and print; 
#Regular expressions in sublime; 

'some (text) here '.match(/\(text\)/)

/1 + 2 = 3?/match("1 + 2 = 3")

#Stuff inside square brackets, as long as it apprears in the square brackets; 

/W[aeiou]+rd/.match("Wierd") #The plus sign means one of more of these; 
/W[aeiou]{2}rd/.match('Wierd') #Curly brackets let you specify a count; 

#Negate a character class using a carot, match anything as long as its not a digit from 0-9; 

/.{4}/ =~ 'shit' #matches a 4 letter word; 
#Modifiyers are the regular expression that will tell the regular expression how to work; 

/foo/.match('FOO') => nil 
/foo/i.match('FOO') => matches! #i means ignore the case(it is a modifiyer); 
/\w/ #Matches a word character; 
/\w\

"hat".match /.at/
m = "bat sat in the mat".match

'#abcdef'.match(/(\h{2})(\h{2})/

#x means extended syntax, it ignores comments and whitespace; 

m = '#absdef'.match(
  /
  (?<red>\h{2})
  (?<green>\h{2})
  (?<blue>\h{2})
  /x
) 

#ANCHORS
/cat/.match('cat')
/^cat/.match('alleycat')
/cat$/.match('alleycat')

#EXERCISE
/(?<word>\s.*a\s)/.match('Mrs. Wilma Flintstone')

1) "Mrs Wilma FintStone".match(/\w+a\b/)

#$ inside pry shows all of the global variables; 
#$$ shows the process id of the current process; 
#$: is the load path what ruby is doing internally; 
#$PROGRAM NAME
$- #This contains the match data; 

'Mrs Wilma. Flinstone' =~ /(\w+a\b/)

ARGF.each do |line|
  if line =~  
    
##REGULAR EXPRESSION JAVSCRIPT
#Literal less typing and more memory effective;
#There are no operators in Javascript you have to do them all through different methods; 

/some/.test('something'); 
('something').match('some');
'something'.replace(/i/, 'I');
'something is interesting'.replace(/i/g, 'I'); #g is global;
'something is interesting'.replace(/[aeiou]/g, function(match) {return match.toUpperCase()});


#https://www.inkling.com/read/learning-perl-schwartz-foy-phoenix-6th/chapter-8/ch08-section-10
#The regExp has test, the string has match; 
##RESOURCE
#mozilla developer network javascript regular expressions; 
#https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions

#Michaels Regular Expression lesson;